TWI801419B - How to start the ammonia oxidation reaction - Google Patents

Abstract

The invention relates to a preheating procedure and starting method of an ammoxidation reaction. The preheating procedure or start-up method at least includes the step of heating the catalyst bed in the ammoxidation reactor under the condition that the operating linear velocity of the reactor is controlled to be 0.03-0.15m/s. Compared with the prior art, the starting method of the present invention has the advantages of significantly shortened starting time and safe operation.

Description

How to start the ammonia oxidation reaction

The present invention relates to the start-up method of chemical production, especially the start-up method of ammoxidation reaction. The present invention also relates to a preheating procedure for the ammoxidation reaction, which is particularly suitable as a preheating step of the start-up method.

Acrylonitrile is an important chemical raw material, which is generally produced industrially by the ammoxidation of propylene (a representative ammoxidation substrate). Before acrylonitrile production reaches steady-state operation, it must go through the start-up method. From the perspectives of production economy and ammoxidation raw material consumption, it is hoped that the start-up time of the start-up method should be as short as possible.

In addition, the raw materials used in the ammoxidation reaction, such as propylene, ammonia, and the reaction products such as acrylonitrile, are combustible substances, and there is a possibility of explosion in an oxygen-containing atmosphere. Therefore, during the entire operation of acrylonitrile production, including during the start-up process, care must be taken to avoid explosion hazards in order to ensure safe production operations.

In addition to propylene, the same requirements exist for the ammoxidation of other substrates for ammoxidation (such as butene and methanol, etc.).

The inventors of the present invention discovered a novel preheating procedure and start-up method of the ammoxidation reaction through assiduous research, and thus completed the present invention.

Specifically, the present invention relates to the contents of the following aspects.

1. A preheating procedure for the ammoxidation reaction, comprising the step of utilizing a heating medium (preferably oxygen-containing gas, especially air) to heat the catalyst bed in the ammoxidation reactor (preferably a fluidized bed reactor), wherein the reaction The operating linear velocity of the reactor is 0.03-0.15m/s (preferably 0.03-0.1m/s), and/or, the input amount of the heating medium into the ammoxidation reactor is 54-276Nm ³ /h/m ² ( Preferably 54-182Nm ³ /h/m ² ).

2. The preheating program according to any of the aforementioned aspects, wherein the catalyst bed is heated to a temperature above 360°C (preferably above 370°C or above 380°C, but preferably below 500°C, below 450°C, or 400°C below or below 390°C).

3. A method for starting an ammoxidation reaction, comprising the following steps: (1) utilizing an oxygen-containing gas (preferably air) to heat the catalyst bed in an ammoxidation reactor (preferably a fluidized bed reactor), wherein the reactor operates The linear velocity is 0.03-0.15m/s (preferably 0.03-0.1m/s), and/or, the input amount of the oxygen-containing gas to the ammoxidation reactor is 54-276Nm ³ /h/m ² (compared to preferably 54-182Nm ³ /h/m ² ); (2) continuously feed ammonia gas into the ammoxidation reactor; (3) continuously feed ammoxidation substrate into the ammoxidation reactor; and (4) optionally , adjusting the input amounts of the oxygen-containing gas, ammonia gas and the ammoxidation substrate into the ammoxidation reactor to respective predetermined values.

4. A starting method for ammoxidation reaction, comprising the following steps: (1) utilizing oxygen-containing gas (preferably air) to heat the catalyst bed in the ammoxidation reactor (preferably fluidized bed reactor); Continuously input ammonia into the ammoxidation reactor; (3) continuously input the ammoxidation substrate into the ammoxidation reactor; and (4) inject the oxygen-containing gas, ammonia and the ammoxidation substrate into the ammoxidation reactor Adjust the respective input amount to the respective predetermined value, Wherein the reactor operating linear velocity of step (1), the reactor operating linear velocity of step (2), the reactor operating linear velocity of step (3) and the reactor operating linear velocity of step (4) are respectively 0.03-0.15m /s, 0.04-0.18m/s, 0.04-0.32m/s and 0.5-1.2m/s, preferably 0.03-0.1m/s, 0.05-0.15m/s, 0.05-0.20m/s (or 0.04-0.17m/s) and 0.65-0.95m/s.

5. The start-up method according to any of the aforementioned aspects, wherein in the step (1), the input amount of the oxygen-containing gas into the ammoxidation reactor is 54-276Nm ³ /h/m ² (preferably 54-276Nm 3 /h/m 2 ). 182Nm ³ /h/m ² ).

6. The starting method according to any of the aforementioned aspects, wherein the ammoxidation substrate is selected from one of C2-20 hydrocarbons (preferably C2-10 hydrocarbons), C1-10 monohydric or polyhydric alcohols, C1-10 monohydric or polyhydric alcohols or Multiple C1-10 alkyl ethers, C1-10 monobasic or polycarboxylic acids and C1-10 monobasic or polycarboxylic acids or at least one of multiple C1-10 alkyl esters, preferably selected from C2-10 straight chain or branched alkanes, C2-10 straight chain or branched olefins, C6-10 aromatic hydrocarbons, C1-10 monoalcohols, C1-4 alkyl ethers of C1-10 monoalcohols, C1-10 monocarboxylic acids and C1-10 At least one of C1-4 alkyl esters of monocarboxylic acids, more preferably selected from C2-4 straight chain or branched chain alkanes, C2-4 straight chain or branched chain alkenes, C1-4 straight chain or branched chain monohydric alcohols , C1-4 straight chain or branched chain monohydric alcohol C1-4 straight chain or branched chain alkyl ether, C1-4 straight chain or branched chain monocarboxylic acid and C1-4 straight chain or branched chain monocarboxylic acid C1- At least one of 4 linear or branched alkyl esters, especially one selected from propane, isobutane, propylene, isobutylene, methanol, ethanol, propanol, dimethyl ether, methyl ethyl ether, acetic acid and methyl acetate at least one.

7. The starting method according to any of the aforementioned aspects, wherein in the step (1), the temperature of the catalyst bed is above 360°C (preferably above 370°C or above 380°C, but preferably below 500°C, 450°C °C, below 400 °C or below 390 °C), and/or, in the step (2), the temperature of the catalyst bed is above 390 °C (preferably above 400 °C, more preferably 400-440 °C), and /or, in the In step (3), the temperature of the catalyst bed is 400-440°C (preferably 400-430°C or 410-430°C), and/or, in the step (4), the temperature of the catalyst bed is 400-550°C or 400-440°C (preferably 400-440°C or 425-440°C).

8. The starting method according to any of the aforementioned aspects, wherein the step (3) is started after the step (2) is carried out for 2-20 minutes (preferably 5-18 minutes), and/or, the step (3) is carried out for 2 Start the step (4) after -50min (preferably 8-43min), and/or, end the starting method after the step (4) for 5-30min (preferably 6-25min), and/or, from the The elapsed time from the start of step (2) to the end of the starting method is 10-100 minutes (preferably 20-60 minutes, more preferably 20-50 minutes).

9. The start-up method according to any of the aforementioned aspects, wherein in the step (2), the target value of the input amount of ammonia gas into the ammoxidation reactor is 7.5-110Nm ³ /h/m ² (preferably 13.7- 69.1Nm ³ /h/m ² or 7.5-45.6Nm ³ /h/m ² ), and the ratio of the input amount target value of the ammonia gas to the input amount value of the oxygen-containing gas is 1:2.5-7 (preferably 1:4-6.5 or 1:4-7), and/or, in the step (3), the input amount target value of the ammoxidation substrate into the ammoxidation reactor is 5.2-110.5Nm ³ /h/ m ² (preferably 9.13-65.8Nm ³ /h/m ² ), and/or, in the step (4), the predetermined input amount of the ammonia oxidation substrate is 110-160Nm ³ /h/m ² (compared to Preferably 117-143Nm ³ /h/m ² ), the input amount of ammonia is 120-230Nm ³ /h/m ² (preferably 120-200Nm ³ /h/m ² or 125-185Nm ³ /h/m ² ), the input amount of the oxygen-containing gas (preferably air) is predetermined to be 600-1600Nm ³ /h/m ² (preferably 990-1600Nm ³ /h/m ² or 1000-1500Nm ³ /h/m ² or 1050-1400Nm ³ /h/m ² ).

10. The start-up method according to any of the aforementioned aspects, wherein the step (3) comprises the following steps: (3-1) keeping the input amount of the ammonia gas in the ammoxidation reactor substantially constant, and starting to oxidize the ammonia gas Put into the ammoxidation substrate in the reactor; and (3-2) adjust (preferably increase) the oxygen-containing gas and the ammoxidation substrate to the ammoxidation reactor The input amount respectively in, wherein the reactor operating linear velocity of step (3-1) and the reactor operating linear velocity of step (3-2) are respectively 0.04-0.18m/s and 0.04-0.32m/s, preferably 0.05-0.15m/s and 0.05-0.2m/s respectively, or 0.05-0.15m/s and 0.04-0.17m/s respectively.

11. The starting method according to any of the aforementioned aspects, wherein the step (3-2) is started after the step (3-1) is carried out for 2-20 minutes (preferably 3-18 minutes), and/or, in the step ( 3-2) start subsequent steps (such as this step (4)) after carrying out 2-30min (preferably 5-25min), and/or, from the starting time of this step (3-1) to this step (3-2) The elapsed time of the end time is 2-50 minutes (preferably 8-43 minutes).

12. The start-up method according to any of the aforementioned aspects, wherein in the step (3-1), the temperature of the catalyst bed is 400-440°C (preferably 400-430°C or 400-415°C), and/ Or, in the step (3-2), the temperature of the catalyst bed is 400-550°C or 420-450°C (preferably 400-440°C or 425-440°C).

13. The start-up method according to any of the aforementioned aspects, wherein in the step (3-1), the input amount of the ammoxidation substrate into the ammoxidation reactor is such that the ammonia oxidized into the ammoxidation reactor The molar ratio of substrate and ammonia reaches 1:4-7, preferably 1:4.5-6.5, and/or, in this step (3-2), adjust (preferably increase) the oxygen-containing gas and The amount of input of the ammoxidation substrate into the ammoxidation reactor is such that the molar ratio of the ammoxidation substrate and ammonia into the ammoxidation reactor reaches 1:0.8 to 1:5 (preferably 1:5) 0.85 to 1:4.5, or 1:1 to 1:1.5, or 1:1.05 to 1:1.3), and make the ammoxidation substrate and the oxygen-containing gas (preferably air, The molar ratio (calculated as molecular oxygen) reaches 1:4 to 1:30 (preferably 1:4.5 to 1:27, or 1:8.5 to 1:11.5, or 1:9 to 1:9.8).

14. The start-up method according to any of the aforementioned aspects, wherein in the step (3-1), the input amount of the ammoxidation substrate into the ammoxidation reactor target value is 1.5-22.1Nm ³ /h/m ² (preferably 2.74-13.8Nm ³ /h/m ² or 1.5-11.4Nm ³ /h/m ² ), and/or, in this step (3-2), the ammoxidation substrate is supplied to the ammoxidation reactor The target value of input amount in the ammoxidation reactor is 5.2-110.5Nm ³ /h/m ² (preferably 9.13-65.8Nm ³ /h/m ² ), and the input amount target value of the oxygen-containing gas into the ammoxidation reactor is 44.2 -1270.7Nm ³ /h/m ² (preferably 82.17-644.9Nm ³ /h/m ² ).

15. The starting method according to any of the foregoing aspects, wherein at the moment when the step (3) starts or at the moment when the step (3-1) starts, the content of molecular oxygen in the reaction tail gas (relative to the total amount of the reaction tail gas volume) is less than 7.5% by volume, preferably 7-7.5% by volume, and/or, at the moment when the step (3-2) starts, the content of molecular oxygen in the reaction tail gas (relative to the total volume of the reaction tail gas) is 2% by volume or less, preferably 0.5-2% by volume.

According to the present invention, one of the following technical effects can be realized, or in a preferred situation, all of these technical effects can be realized simultaneously.

(1) The start-up time of the start-up method is significantly shortened, and the consumption of ammoxidation reaction raw materials (especially ammoxidation substrate and ammonia gas) is also significantly reduced correspondingly. According to a preferred embodiment of the present invention, the starting time of the starting method is generally 10-100 minutes, preferably 20-60 minutes, more preferably 20-50 minutes. According to another preferred embodiment of the present invention, the start-up time of the starting method is substantially 80% or less, 70% or less, 60% or less, 50% or less of the corresponding start-up time of the prior art , 40% or less, 30% or less, 20% or less, 10% or less, 5% or less, 1% or less, 0.5% or less, 0.25% or less, even 0.1% or less.

(2) The operation of the ammoxidation reaction is safe and the risk of explosion is low.

The specific implementations of the present invention will be described in detail below, but it should be pointed out that the scope of protection of the present invention is not limited by these specific implementations, but is determined by the scope of patent application in the appendix.

All publications, patent applications, patents, and other references mentioned in this specification are hereby incorporated by reference in their entirety. Unless otherwise defined, all technical and scientific terms used in this specification have the meaning commonly understood by those skilled in the art. In case of conflict, the present specification's definitions will control.

When this specification uses the prefixes "well known to those skilled in the art", "prior art", "conventionally known in the art" or similar terms to describe materials, substances, methods, steps, devices or components, etc., such The objects derived from the prefixes include those that are commonly used in the art when this application is filed, but also include those that are not commonly used at present, but will become recognized in the art as being suitable for similar purposes.

In the context of the present invention, the term "ammoxidation reactor" must be understood according to the usual meaning in the field of production of chemicals such as acrylonitrile and methacrylonitrile. For example, it refers to any reactor suitable for ammoxidation reaction, including but not limited to fixed bed reactor and fluidized bed reactor, preferably fluidized bed reactor.

In the context of the present invention, the term "start-up method" must be understood according to the usual meaning in the field of production of chemicals such as acrylonitrile and methacrylonitrile. For example, it refers to the preheating of the catalyst bed in the ammoxidation reactor (corresponding to the preheating step) until the input amount of all the ammoxidation reaction raw materials into the reactor reaches the predetermined value when the reactor operates stably the whole process. Specifically, as the preheating step, it is sometimes also referred to as a preheating program in the context of the present invention. In addition, in the context of the invention of the present application, from the end of the preheating step until the input amount of all ammoxidation reaction raw materials into the reactor reaches the stable operation of the reactor The entire process up to the predetermined value of time is called "startup procedure".

In the context of the present invention, the term "start-up time" refers to the entire process from the end of the preheating step until the amount of input of all ammoxidation reaction raw materials into the ammoxidation reactor reaches the predetermined value when the reactor is in stable operation. The overall elapsed time, or the overall time elapsed from the beginning to the end of the start-up process, usually in minutes or hours.

In the context of the present invention, the term "reactor operating linear velocity" or "operating linear velocity" or similar expressions must be understood according to the usual meaning in the field of production of chemicals such as acrylonitrile and methacrylonitrile. For example, referring to the velocity of fluid flow in the reactor, the linear velocity can be calculated according to the following formula (1):

In the formula (1), Q is the total flow rate of the fluid entering the reactor, the unit is Nm ³ /h; S is the effective cross-sectional area of the reactor, the unit is m ² ; Tr is the temperature in the reactor, the unit is K; Tn is 273.15K; Pr is the top pressure of the reactor, the unit is Pa; Pn is the standard atmospheric pressure, the unit is Pa; N is the reaction gas expansion ratio; V is the reactor operating linear velocity, the unit is m/s.

In the context of the present invention, the term "input amount" refers to the input of a certain ammoxidation reaction raw material (such as ammoxidation substrate, ammonia gas and oxygen-containing gas, especially propylene, ammonia gas and air) into the ammoxidation reactor The flow rate, that is, the feeding amount q, can be calculated according to the following formula (2), and the unit is Nm ³ /h/m ² , which means the gas standard volume flow per hour per square meter of reactor cross-sectional area.

In formula (2), Q is the flow rate into the reactor, the unit is Nm ³ /h, S is the effective cross-sectional area of the reactor, the unit is m ² .

In the context of the present invention, the term "target value" or "predetermined value" must be understood according to the usual meaning in the field of production of chemicals such as acrylonitrile and methacrylonitrile. For example, it refers to the value (also known as the final value) that a certain parameter (such as input amount, temperature, pressure, etc.) needs to reach at the end of the starting method, preheating program, starting program or a certain operation step of these programs ). At the beginning of the procedures or the operating steps, the parameter can be any value (called initial value), such as 0 or the final value. Specifically, for example, the parameter may reach the final value at the beginning of one of the procedure or the operating steps, and remain constant or substantially (such as deviating by no more than ±10%, preferably by no more than ±5%) from the beginning to the end. value. Alternatively, the parameter can be varied from the initial value to the final value. For example, with respect to how the initial value changes to the final value, the parameter changes from the initial value as the procedure or the operation step proceeds (either by voluntary variation or external intervention, preferably external intervention such as regulation or control ) to this final value. As the change, such as increasing, subtracting, etc. according to any conventionally known changing mode in this technology (such as stepwise mode, linear mode, jump mode, pulse mode, curve mode, mode conforming to a certain formula or law, etc.) Small or a combination thereof is not particularly limited.

In the context of the present invention, the term "hydrocarbon" includes linear, branched or cyclic alkanes, linear, branched or cyclic alkenes, and aromatic hydrocarbons. These hydrocarbons may be used alone or in combination of two or more.

In the context of the present invention, the term "ammoxidation substrate" must be understood according to the usual meaning in the field of production of chemicals such as acrylonitrile and methacrylonitrile. For example, refers to any organic compound that can undergo an ammoxidation reaction with ammonia and molecular oxygen, such as to form nitriles. As such organic compounds, specific examples include C2-20 hydrocarbons (preferably C2-10 hydrocarbons), C1-10 monohydric or polyhydric alcohols, one of C1-10 monohydric or polyhydric alcohols or multiple C1-10 alkyl ethers, C1-10 monobasic or polycarboxylic acids and one or more C1-10 alkyl esters of C1-10 monobasic or polycarboxylic acids. do As the organic compound, more specifically C2-10 straight chain or branched alkanes, C2-10 straight chain or branched alkenes, C6-10 aromatic hydrocarbons, C1-10 monohydric alcohols, C1-10 monohydric alcohols, etc. -4 alkyl ethers, C1-10 monocarboxylic acids and C1-4 alkyl esters of C1-10 monocarboxylic acids. As such organic compounds, more specifically, C2-4 straight chain or branched alkanes, C2-4 straight chain or branched alkenes, C1-4 straight chain or branched monohydric alcohols, C1-4 straight chain or branched C1-4 straight chain or branched chain alkyl ether of chain monohydric alcohol, C1-4 straight chain or branched chain monocarboxylic acid and C1-4 straight chain or branched chain alkyl of C1-4 straight chain or branched chain monocarboxylic acid ester. Specific examples of such organic compounds include propane, isobutane, propylene, isobutylene, methanol, ethanol, propanol, dimethyl ether, methyl ethyl ether, acetic acid and methyl acetate, and more particularly propylene. These ammoxidation substrates or organic compounds may be used alone or in combination of two or more. Moreover, it is obvious to those skilled in the art that these ammoxidation substrates or organic compounds, as one of the ammoxidation raw materials, are generally in a gaseous state at least when entering the ammoxidation reactor, but when entering the ammoxidation reaction Before the reactor, it can be in a gaseous state, a liquid state or a combination thereof, and is not particularly limited.

In the context of the present invention, the term "ammonia" refers to the ammonia as one of the raw materials for the ammoxidation reaction, which is at least in a gaseous state when it enters the ammoxidation reactor, but before entering the ammoxidation reactor, it may be in a gaseous state. Gas or liquid or a combination thereof is not particularly limited. As will be apparent to those skilled in the art, the ammonia gas may be of any purity acceptable for the ammoxidation reaction, or may include no purity for the ammoxidation reaction in any manner conventionally known in the art. Any impurities or diluents (such as nitrogen, etc.) that adversely affect, or can also be pretreated in any manner conventionally known in the art (such as removing harmful impurities, etc.) are not particularly limited.

In the context of the present invention, the term "oxygen-containing gas" refers to any gas containing molecular oxygen, such as air, oxygen, oxygen-enriched air, oxygen-depleted air, human Make the mixture of air or oxygen and other gases (such as nitrogen or water vapor), etc. Those who are skilled in this technology can choose arbitrarily according to the actual situation or actual needs. However, from the standpoint of convenient operation and production economy of the ammoxidation reaction, air is particularly mentioned.

In the context of the invention of this application, in order to simplify the description, any technical details or technical features that are not specifically described, such as fluidized bed operation mode, ammoxidation reaction mode, reaction tail gas absorption method and reaction raw material pretreatment method, etc. Information can directly refer to relevant information known in this technology without substantial modification, so it will not be repeated here.

Unless otherwise specified, all percentages, parts, ratios, etc. mentioned in this specification are based on weight; This conventional knowledge of those skilled in the art shall prevail.

It should be noted that two or more aspects (or implementations) disclosed in the context of this specification can be combined with each other arbitrarily, and the resulting technical solutions (such as methods or systems) belong to the original disclosure of this specification. part of the content.

According to the present invention, it first relates to a preheating procedure for the ammoxidation reaction. Known by those skilled in the art, as the starting method of the ammoxidation reaction, at first the step of heating the catalyst bed in the ammoxidation reactor to an appropriate temperature by some means (such as contacting with a heating medium) must be included ( called the warm-up step). Here, the preheating procedure corresponds to the preheating step of the starting method.

According to one aspect of the present invention, the preheating procedure includes the step of using a heating medium to heat the catalyst bed in the ammoxidation reactor. Here, as the heating medium, any heating medium known in the art that can be used in the preheating step of the ammoxidation reaction can be used. Specific examples of the heating medium include water vapor, nitrogen, and oxygen-containing gases, particularly Lift up the air. These heating media may be used alone or in combination of two or more.

According to an aspect of the present invention, in the preheating procedure, the operating linear velocity of the ammoxidation reactor is 0.03-0.15 m/s, preferably controlled to be 0.03-0.1 m/s. For this reason, the operating line speed of the reactor can be conveniently realized by adjusting the input flow rate or input amount of the heating medium into the ammoxidation reactor. The inventors of the present invention have unexpectedly found that by limiting the operating linear velocity of the reactor within the special range, the start-up time of the start-up method of the present invention can be significantly shortened, and the consumption of ammoxidation reaction raw materials is also correspondingly significant reduce.

According to one aspect of the present invention, in the preheating procedure, the input amount of the heating medium into the ammoxidation reactor is generally 54-276Nm ³ /h/m ² , preferably 54-182Nm ³ /h/ m ² . For this reason, the input amount can be conveniently adjusted, for example, by adjusting the input flow rate of the heating medium into the ammoxidation reactor. The inventors of the present invention unexpectedly found that by limiting the input amount within the special range, the start-up time of the start-up method of the present invention can be significantly shortened, and the consumption of raw materials for the ammoxidation reaction is also significantly reduced accordingly.

Without being bound by any theory, the inventors of the present invention believe that by using a lower reactor operating linear velocity or heating medium input than in the prior art, at the end of the preheating step, the ammonia oxidizes The total residual amount of the heating medium in the reactor is significantly reduced, and thus the total amount of the heating medium that needs to be disposed of (such as blown off or consumed) in the subsequent start-up procedure is also significantly reduced. For this reason, each ammoxidation reaction raw material can quickly meet the requirements stipulated for the stable operation of the ammoxidation reactor, resulting in a significant reduction in the respective consumption of these reaction raw materials. And, especially under the situation that the heating medium is oxygen-containing gas (especially air), if the operating line speed or the input amount exceed the range specified by the present invention, since the amount of oxygen-containing gas entering the reactor is relatively large, It is not ruled out that in the subsequent start-up procedure, there will be instantaneous exposure of incompletely reacted ammonia gas to a certain Oxygen concentrations which may result in an explosion hazard. In addition, if the operating line speed or the input amount is lower than the scope specified in the present invention, it will easily lead to poor fluidization quality of the catalyst, making the reaction process of the ammoxidation reaction raw materials insufficient, resulting in an increase in the proportion of unreacted ammonia in the system, This increases the risk of explosion accidents.

According to one aspect of the present invention, by the preheating step or preheating procedure, the catalyst bed in the ammoxidation reactor is heated to any temperature that can be expected when the ammoxidation reactor is preheated in this technology, Specific examples include 360°C or higher, 370°C or higher, or 380°C or higher, or roughly 500°C or lower, 450°C or lower, 400°C or lower, or 390°C or lower, without any particular limitation. . In addition, the present invention has no special limitation on the time required or experienced by the preheating step or preheating program, and the time needs to be determined according to whether each section of the production device has the necessary conditions for start-up operation, and it is generally very short. Difficult to estimate in advance. Also, as the temperature increase rate of the heating, any value conventionally known in the art can be referred to, but as an example, it is usually 10-100° C./h.

According to one aspect of the present invention, in the preheating step or preheating program, the pressure (gauge pressure) in the ammoxidation reactor is generally 0.030-0.060MPa, preferably 0.030-0.055MPa, but sometimes not Not limited to this.

According to one aspect of the present invention, the catalyst used is not particularly limited, as long as it is known in the art to make the ammoxidation reaction (such as generating nitrile compounds) of the ammoxidation substrate, ammonia gas and molecular oxygen Any catalyst can be used. Examples of such catalysts include Mo-Bi-based/supported catalysts, Mo-Fe-based/supported catalysts, and Mo-V-based/supported catalysts containing active element Mo, or Sb-Fe-based/supported catalysts containing active element Sb. wait. These catalysts may be used alone or in combination of two or more. Here, examples of such carriers include alumina and silica. These carriers can be used alone or in combination of two or more use. As the particle size distribution of these catalysts, for example, the average particle size is 40-80 μm, and calculated by weight percentage, the particle size is greater than 90 μm, accounting for 0-30%, and the particle size is less than 45 μm, accounting for 30%. -50%, and the particle size is less than 20μm not higher than 10%. The shape of the particles of these catalysts includes, for example, a spherical shape, a cylindrical shape, a ring shape, a quincunx shape, and a clover shape. For example, the reporter catalyst particles generally have an outer diameter of 1-10 mm and a length of generally 2-10 mm. The catalyst can be purchased directly from the market, or can be produced according to any method conventionally known in the art.

According to one aspect of the present invention, there is no particular limitation on the types of the ammoxidation reactors, and specific examples include fixed-bed reactors and fluidized-bed reactors, preferably fluidized-bed reactors. For example, the fluidized bed reactor may include a gas distribution plate, a gas distributor, a cooling water pipe, a cyclone separator, and the like. For this purpose, the oxygen-containing gas or heating medium can enter the interior of the fluidized bed reactor through the gas distribution plate, and the ammoxidation substrate and/or ammonia gas can enter the fluidized bed reaction through the gas distributor inside the device. The cooling water pipe can remove excess heat inside the reactor, and the cyclone separator can return the catalyst entrained by the gas to the lower end of the reactor. In addition, the fluidized bed reactor is equipped with several monitoring points for measuring temperature and pressure, which can intuitively reflect the operating status of the reaction system on the DCS control system, including the input amount of each reaction raw material and heating medium ( Expressed in Nm ³ /h or Nm ³ /h/m ² ), the operating line speed of the reactor, etc.

According to an aspect of the present invention, after the preheating procedure or the preheating step is completed, the start-up procedure of the ammoxidation reaction start-up method can be subsequently carried out according to any method and any method known to those skilled in the art. For this reason, in order to carry out the start-up procedure, such as after the completion of the preheating procedure or the preheating step, in the ammoxidation reactor, according to any method known in the art and any method, each ammoxidation reaction raw material is put into (comprising ammonia, oxygen-containing gas and ammoxidation substrates, especially ammonia, air and propylene), and adjusting the input of these ammoxidation reaction raw materials to the ammoxidation reactor separately or in combination as required, until all of these The input amount of the ammoxidation reaction raw material in the ammoxidation reactor reaches the predetermined value when the ammoxidation reactor operates stably.

According to one aspect of the present invention, it also relates to a method for starting an ammoxidation reaction. It is known in the art that the start-up method of the ammoxidation reaction must include a preheating step and a start-up procedure. Preferably, the preheating step may correspond to the aforementioned preheating procedure in this specification.

According to one aspect of the present invention, the starting method of the ammoxidation reaction comprises the following steps: (1) heating the catalyst bed in the ammoxidation reactor with an oxygen-containing gas (sometimes referred to as a preheating step); Ammonia is continuously fed into the ammoxidation reactor; (3) an ammoxidation substrate is continuously fed into the ammoxidation reactor; and (4) optionally, the oxygen-containing gas, ammonia and the ammoxidation substrate are injected into the ammoxidation reactor The respective inputs in the ammoxidation reactor are adjusted to respective predetermined values.

According to one aspect of the present invention, in the step (1), air is particularly mentioned as the oxygen-containing gas.

According to an aspect of the present invention, in the step (1), the operating linear velocity of the ammoxidation reactor is 0.03-0.15 m/s, preferably controlled to be 0.03-0.1 m/s. For this reason, the operating line speed of the reactor can be conveniently realized by adjusting the input flow rate or input amount of the heating medium into the ammoxidation reactor. The inventors of the present invention have unexpectedly found that by limiting the operating linear velocity of the reactor within the special range, the start-up time of the start-up method of the present invention can be significantly shortened, and the consumption of ammoxidation reaction raw materials is also correspondingly significant reduce.

According to one aspect of the present invention, in the step (1), the input amount of the heating medium into the ammoxidation reactor is generally 54-276Nm ³ /h/m ² , preferably 54-182 Nm ³ / h/m ² . For this reason, the input amount can be conveniently adjusted, for example, by adjusting the input flow rate of the heating medium into the ammoxidation reactor. The inventors of the present invention unexpectedly found that by limiting the input amount within the special range, the start-up time of the start-up method of the present invention can be significantly shortened, and the consumption of raw materials for the ammoxidation reaction is also significantly reduced accordingly.

Without being bound by any theory, the inventors of the present invention believe that by using a lower reactor operating line speed or oxygen-containing gas input than the prior art, at the end of the preheating step, the The total residual amount of the oxygen-containing gas in the ammoxidation reactor is significantly reduced, and thus the total amount of the oxygen-containing gas that needs to be treated (such as blown off or consumed) in the subsequent start-up procedure will also be significantly reduced. For this reason, each ammoxidation reaction raw material can quickly meet the requirements stipulated for the stable operation of the ammoxidation reactor, resulting in a significant reduction in the respective consumption of these reaction raw materials. Moreover, if the operating line speed or the input amount exceeds the range specified by the present invention, since the amount of oxygen-containing gas entering the reactor is relatively large, it is not ruled out that in the subsequent start-up procedure, there is instantaneous exposure of incompletely reacted ammonia gas to a certain amount. In the case of oxygen concentration, it may cause explosion hazard. In addition, if the operating line speed or the input amount is lower than the scope specified in the present invention, it will easily lead to poor fluidization quality of the catalyst, making the reaction process of the ammoxidation reaction raw materials insufficient, resulting in an increase in the proportion of unreacted ammonia in the system, This increases the risk of explosion accidents.

According to one aspect of the present invention, through this step (1), the catalyst bed in the ammoxidation reactor is heated to any temperature that can be expected when the ammoxidation reactor is preheated in this technology, specifically such as Examples include 360°C or higher, 370°C or higher, or 380°C or higher, or roughly 500°C or lower, 450°C or lower, 400°C or lower, or 390°C or lower, but are not particularly limited. In addition, the present invention has no special limitation on the time required or elapsed in step (1), and the time needs to be determined according to whether each section of the production device has the necessary conditions for start-up operation, and it is generally difficult to estimate in advance . Moreover, as the temperature rise rate of the heating The rate can refer to any numerical values conventionally known in this art, but as an example, it is generally 10-100° C./h.

According to one aspect of the present invention, in the step (1), the pressure (gauge pressure) in the ammoxidation reactor is generally 0.030-0.060MPa, preferably 0.030-0.055MPa, but sometimes it is not limited thereto .

According to one aspect of the present invention, the catalyst used is not particularly limited, as long as it is known in the art to make the ammoxidation reaction (such as generating nitrile compounds) of the ammoxidation substrate, ammonia gas and molecular oxygen Any catalyst can be used. Examples of such catalysts include Mo-Bi-based/support, Mo-Fe-based/supported catalysts, Mo-V-based/supported catalysts, etc. containing active element Mo, or Sb-Fe-based/supported containing active element Sb. Catalyst etc. These catalysts may be used alone or in combination of two or more. Here, examples of such carriers include alumina and silica. These carriers may be used alone or in combination of two or more. As the particle size distribution of these catalysts, for example, the average particle size is 40-80 μm, and calculated by weight percentage, the particle size is greater than 90 μm, accounting for 0-30%, and the particle size is less than 45 μm, accounting for 30%. -50%, and the particle size is less than 20μm not higher than 10%. The shape of the particles of these catalysts includes, for example, a spherical shape, a cylindrical shape, a ring shape, a quincunx shape, and a clover shape. For example, the outer diameter of the catalyst particles is generally 1-10 mm, and the length is generally 2-10 mm. The catalyst can be purchased directly from the market, or can be produced according to any method conventionally known in the art.

According to an aspect of the present invention, there is no particular limitation on the type of the ammoxidation reactor, such as a fixed bed reactor and a fluidized bed reactor, preferably a fluidized bed reactor. For example, the fluidized bed reactor may include a gas distribution plate, a gas distributor, a cooling water pipe, a cyclone separator, and the like. For this purpose, the oxygen-containing gas or heating medium can enter the interior of the fluidized bed reactor through the gas distribution plate, and the ammoxidation substrate and/or ammonia gas can enter the fluidized bed reaction through the gas distributor inside the device. The cooling water pipe can remove excess heat inside the reactor, and the cyclone separator can return the catalyst entrained by the gas to the lower end of the reactor. In addition, the fluidized bed reactor is equipped with several monitoring points for measuring temperature and pressure, which can intuitively reflect the operating status of the reaction system on the DCS control system, including the input amount of each reaction raw material and heating medium ( Expressed in Nm ³ /h or Nm ³ /h/m ² ), the operating line speed of the reactor, etc.

According to an aspect of the present invention, after the preheating step of the step (1) is completed, the start-up procedure of the ammoxidation reaction can be started. Here, the start-up procedure at least includes the aforementioned step (2), step (3) and step (4), or covers the entire process from the beginning of the step (2) to the end of the step (4).

According to one aspect of the present invention, in the step (2), ammonia gas is continuously fed into the ammoxidation reactor.

According to an aspect of the present invention, in the step (2), the temperature of the catalyst bed is generally above 390°C, preferably above 400°C, more preferably 400-440°C. After the ammonia gas is injected, the heat released by the ammoxidation reaction causes the temperature in the ammoxidation reactor to rise compared with that before the ammonia injection, which can generally reach the initial temperature of the ammoxidation substrate for the ammoxidation reaction. In order to prevent the temperature from being too high, during the step (2), sometimes a certain number of cooling coils need to be put in simultaneously to control the temperature of the catalyst bed.

According to one aspect of the present invention, in the step (2), the input amount target value of ammonia gas into the ammoxidation reactor is generally 7.5-110Nm ³ /h/m ² , 13.7-69.1Nm ³ /h /m ² or 7.5-45.6Nm ³ /h/m ² . Specifically, in the case where the ammoxidation substrate is propylene, the target value is generally 7.5-45.6 Nm ³ /h/m ² . As the input method of ammonia, such as can be cited according to any conventionally known method in this technology or any method gradually (such as divided into multiple times, multi-step or continuous) to increase to the target value from a small dose, and can also be achieved at one time. The target value is not particularly limited. In the case of adopting the ammonia gas input method that starts from a small dose and gradually increases to the target value, it can avoid damage to the regulating valve caused by the instantaneous large flow rate, and also reduce the static electricity that may be generated in the pipeline when the instantaneous large flow rate is used.

According to an aspect of the present invention, in the step (2), the ratio of the input amount target value of the ammonia gas to the input amount value of the oxygen-containing gas is generally 1:2.5-7, preferably 1:4- 6.5. For this reason, it is obvious to those skilled in the art that in order to make the ratio reach the scope specified by the present invention, while adjusting or controlling the input amount of ammonia in the ammoxidation reactor, sometimes it is necessary to Correspondingly adjust or control the input amount of the oxygen-containing gas into the ammoxidation reactor. The present invention has no special limitation on the input amount of the oxygen-containing gas into the ammoxidation reactor in the step (2), as long as the ratio of the input amount can meet the requirements specified in the present invention. According to needs, the input amount of the oxygen-containing gas into the ammoxidation reactor can also be kept substantially constant during the whole process of the step (2). For the sake of convenient operation, at least when the step (2) starts, the input amount of the oxygen-containing gas into the ammoxidation reactor can be the corresponding value that has been reached when the step (1) ends, specifically such as 54-276Nm ³ /h/m ² . In addition, the so-called "substantially constant" means that the numerical value remains absolutely constant or the variation range of the numerical value is within ±10% (preferably ±5%).

According to one aspect of the present invention, in the step (2), the pressure (gauge pressure) in the ammoxidation reactor is generally 0.030-0.060MPa, preferably 0.030-0.040MPa, but sometimes it is not limited thereto .

According to an aspect of the present invention, in the step (2), the operating linear velocity of the reactor is generally 0.04-0.18 m/s, preferably 0.05-0.15 m/s.

According to an aspect of the present invention, the step (3) starts after the step (2) is carried out for 2-20 minutes. Preferably, the step (3) starts after the step (2) is carried out for 5-18 minutes. as well as That is, for example, the step (3) is started when the step (2) is carried out to 2-20min, or the step (2) is finished after 2-20min, and then the step (3) is started, and other similar Expressions can be understood similarly. In addition, in the context of the invention of the present application, for example, the word "end" is sometimes used for a certain step. The "end" only means that the step is merged and does not exist by its subsequent steps, but it does not mean that the step involves The material conveying operation was also terminated. Specifically, for example, step (2) is related to continuously injecting ammonia gas into the ammoxidation reactor. The so-called "step (2) ends" only means that step (2) is replaced by subsequent step (3) or step (3) -1) does not exist, but the continuous ammonia input operation involved in the step (2) still exists in the subsequent step (3) or step (3-1) without termination. Other similar expressions can be understood similarly.

According to one aspect of the present invention, in the step (3), the ammoxidation substrate, especially propylene, is continuously fed into the ammoxidation reactor.

According to one aspect of the present invention, at the moment when the step (3) starts, from the perspective of increasing the operational safety or reducing the risk of explosion of the reaction mixture in the ammoxidation reactor, such as because the composition is within the explosion limit range, the reaction tail gas (That is, the tail gas discharged from the outlet of the ammoxidation reactor) has a molecular oxygen content (relative to the total volume of the tail gas) of generally less than 7.5% by volume, preferably 7-7.5% by volume.

According to one aspect of the invention, ammonia enters the ammoxidation reactor preferentially over the ammoxidation substrate, such as propylene. From the analysis of the MSDS characteristics of the substance, ammonia gas has a higher lower limit of the explosive limit than the ammonia oxidation substrate, that is, in the same oxygen-containing atmosphere, within the concentration range from 0 to the lower limit of the explosive limit, ammonia gas is allowed to flow in the system during the operation process The safe operating concentration of the ammonia oxidation substrate is obviously greater than the safe operating concentration of the ammonia oxidation substrate in the system. The reaction feed ammonia enters the reactor before the ammonia oxidation substrate. Compared with the ammonia oxidation substrate, the ammonia gas enters the reactor before the ammonia oxidation substrate. The former reduces the risk of explosion and greatly improves the safety factor.

According to an aspect of the present invention, in the step (3), the temperature of the catalyst bed is generally 400-440°C, preferably 400-430°C or 410-430°C. In order to prevent the temperature from being too high, during the step (3), sometimes a certain number of cooling coils need to be synchronously put in to control the temperature of the catalyst bed.

According to one aspect of the present invention, in the step (3), the input amount target value of the ammoxidation substrate into the ammoxidation reactor is generally 5.2-110.5Nm ³ /h/m ² , preferably 9.13- 65.8Nm ³ /h/m ² . At this time, the present invention has no special limitation on the input amount of the oxygen-containing gas and the ammonia gas in the ammoxidation reactor or the change mode of the input amount. Those skilled in the art can choose arbitrarily according to the situation, as long as the It is sufficient that the ammoxidation reaction between raw materials for the ammoxidation reaction can at least occur without causing an explosion risk. Specifically, as the input amount of the oxygen-containing gas into the ammoxidation reactor, for example, 44.2-1270.7 Nm ³ /h/m ² can be mentioned, but the present invention is not limited thereto. In addition, as a specific example, the input amount of ammonia gas into the ammoxidation reactor may specifically include 7.5-110 Nm ³ /h/m ² , but the present invention is not limited thereto.

According to one aspect of the present invention, in the step (3), the pressure (gauge pressure) in the ammoxidation reactor is generally 0.030-0.060MPa, preferably 0.030-0.045MPa, but sometimes it is not limited thereto .

According to an aspect of the present invention, in the step (3), the operating linear velocity of the reactor is generally 0.04-0.32 m/s, preferably 0.05-0.20 m/s or 0.04-0.17 m/s.

According to an aspect of the present invention, from the perspective of avoiding the risk of explosion, the step (3) includes at least step (3-1) and step (3-2).

Step (3-1): Keeping the input amount of the ammonia gas into the ammoxidation reactor substantially constant, start inputting the ammoxidation substrate into the ammoxidation reactor. Here, the so-called "substantially constant" means that the numerical value remains absolutely constant or the variation range of the numerical value is within ±10% (preferably ±5%). Here, for the convenience of operation, the input amount of ammonia gas in the ammoxidation reactor can be the input amount of ammonia gas in the ammoxidation reactor when the step (2) ends, such as substantially 7.5- 110Nm ³ /h/m ² , 13.7-69.1Nm ³ /h/m ² or 7.5-45.6Nm ³ /h/m ² . Specifically, when the ammoxidation substrate is propylene, the input amount of ammonia gas is generally 7.5-45.6 Nm ³ /h/m ² .

According to one aspect of the present invention, at the moment when the step (3-1) starts, from the perspective of increasing the operational safety or reducing the reaction mixture in the ammoxidation reactor, such as the risk of explosion caused by the composition being within the explosion limit range, The molecular oxygen content (relative to the total volume of the tail gas) in the reaction tail gas (that is, the tail gas discharged from the outlet of the ammoxidation reactor) is generally below 7.5% by volume, preferably 7-7.5% by volume.

According to an aspect of the present invention, in the step (3-1), the temperature of the catalyst bed is 400-440°C, 400-430°C or 400-415°C. In order to prevent the temperature from being too high, during the step (3-1), sometimes a certain number of cooling coils need to be put in simultaneously to control the temperature of the catalyst bed.

According to one aspect of the present invention, in the step (3-1), the pressure (gauge pressure) in the ammoxidation reactor is generally 0.030-0.060MPa, preferably 0.030-0.040MPa, but sometimes not limited to this.

According to one aspect of the present invention, in the step (3-1), the molar ratio of the ammoxidation substrate and ammonia gas fed into the ammoxidation reactor is generally 1:4-7, preferably 1: 4.5-6.5. The molar ratio can be realized by any conventionally known method in the art, such as by adjusting the input amount of the ammoxidation substrate into the ammoxidation reactor, and there is no special limitation.

According to an aspect of the present invention, in the step (3-1), the input amount target value of the ammoxidation substrate into the ammoxidation reactor can be 1.5-22.1Nm ³ /h/m ² , 2.74-13.8 Nm ³ /h/m ² or 1.5-11.4Nm ³ /h/m ² . Specifically, when the ammoxidation substrate is propylene, the target input amount is generally 1.5-11.4 Nm ³ /h/m ² . When feeding the ammoxidation substrate (especially propylene) into the ammoxidation reactor, it can be gradually increased from a small dose (such as divided into multiple times, multi-steps or continuously) to the target value, and the target value can also be reached at one time , is not particularly limited. Once the ammoxidation substrate is introduced, under the action of the catalyst, the ammoxidation reaction of the substrate will proceed immediately under the current temperature conditions. The rate of the ammoxidation reaction is very fast, and more molecular oxygen will be consumed in the reaction process, so that the content of molecular oxygen in the reaction tail gas will further decrease, and the heat of reaction will be released at the same time. Due to the further reduction of the molecular oxygen content in the ammoxidation reactor, the explosion limit of the reaction products such as acrylonitrile and other combustible substances can be avoided, and it is also a low target value (compared with the prior art) when inputting the ammoxidation substrate. reason.

According to an aspect of the present invention, the step (3-2) starts after the step (3-1) is performed for 2-20 minutes. Preferably, the step (3-2) starts after the step (3-1) is carried out for 3-18 minutes.

Step (3-2): Adjusting the input amounts of the oxygen-containing gas and the ammoxidation substrate into the ammoxidation reactor. Here, as this adjustment, any method known in the art can be used. For example, such as by changing the flow regulating device (such as valve, flow meter or orifice plate) on the pipeline used to transport the oxygen-containing gas and/or the ammoxidation substrate into the ammoxidation reactor. etc.), thereby changing the input amount. In addition, as the adjustment method, for example, it can be mentioned that the initial input amount is gradually increased (such as divided into multiple times, multi-step or continuously) to the corresponding target value.

According to an aspect of the present invention, at the moment when the step (3-2) starts, the reaction mixture in the ammoxidation reactor, such as from increasing the operational safety or reducing the composition, is at the explosive extreme From the perspective of causing explosion risk within the limited range, the content of molecular oxygen in the reaction tail gas (relative to the total volume of the tail gas) is generally less than 2% by volume, preferably 0.5-2% by volume. In addition, from the perspective of avoiding the reduction of catalyst activity, it is preferable to adjust the input of the oxygen-containing gas and the ammoxidation substrate into the ammoxidation reactor during the entire process of the step (3-2). amount, thereby keeping the content of molecular oxygen in the reaction tail gas (relative to the total volume of the tail gas) always within the range of 0.5-2 volume%.

According to one aspect of the present invention, in this step (3-2), depending on the type of ammoxidation substrate, the temperature of the catalyst bed is generally 400-550°C, 420-450°C, 400-440°C or 425-440°C. Specifically, when the ammoxidation substrate is propylene, the temperature is generally 420-450°C, preferably 425-440°C. In order to prevent the temperature from being too high, during the step (3-2), sometimes a certain number of cooling coils need to be synchronously put in to control the temperature of the catalyst bed.

According to one aspect of the present invention, in the step (3-2), the pressure (gauge pressure) in the ammoxidation reactor is generally 0.030-0.060MPa, preferably 0.035-0.045MPa, but sometimes not limited to this.

According to an aspect of the present invention, in the step (3-2), adjust or gradually increase (such as divided into multiple times, multi-step or continuous) the oxygen-containing gas and the ammoxidation substrate into the ammoxidation reactor respectively The amount of input, so that the molar ratio (ammonia ratio) of the ammonia oxidation substrate and ammonia gas and/or the molar ratio of the ammonia oxidation substrate and the oxygen-containing gas (calculated as molecular oxygen) into the ammoxidation reactor The ratio (empty ratio) reaches the ratio parameter when the device is in normal operation. According to the specific size of the reactor and the layout of its internal components, the proportion parameters of the reactor during normal operation are also different. Specifically, for example, the ammonia ratio is generally 1:0.8 to 1:5, preferably 1:0.85 to 1:4.5. Specifically, for example, the duty ratio is generally 1:4 to 1:30, preferably 1:4.5 to 1:27. In further detail, when the ammoxidation substrate is propylene, the ammonia ratio is generally 1:1 to 1:1.5, preferably 1:1.05 to 1:1.3. In further detail, when the ammoxidation substrate is propylene, the void ratio is generally 1:8.5 to 1:11.5, preferably 1:9 to 1:9.8. In addition, it is obvious to those skilled in the art that in order to make these ratios reach the range specified by the present invention, while adjusting the input amounts of the oxygen-containing gas and the ammoxidation substrate into the ammoxidation reactor, , Sometimes it is necessary to adjust or control the input amount of ammonia gas into the ammoxidation reactor accordingly according to the situation. The present invention has no special limitation on the input amount of ammonia gas into the ammoxidation reactor in the step (3-2), as long as these ratios can meet the requirement of the present invention and the risk of explosion will not be generated. According to needs, the input amount of ammonia gas into the ammoxidation reactor can also be maintained substantially constant during the whole process of the step (3-2). For the convenience of operation, at least when the step (3-2) starts, the input amount of ammonia to the ammoxidation reactor can be the corresponding value that has been reached when the step (3-1) ends, specifically such as 7.5-110 Nm ³ /h/m ² or 7.5-45.6 Nm ³ /h/m ² are mentioned. In addition, the so-called "substantially constant" means that the numerical value remains absolutely constant or the variation range of the numerical value is within ±10% (preferably ±5%).

According to one aspect of the present invention, in the step (3-2), the input amount target value of the ammoxidation substrate into the ammoxidation reactor is 5.2-110.5Nm ³ /h/m ² , preferably 9.13- 65.8Nm ³ /h/m ² , the target value of the input amount of the oxygen-containing gas into the ammoxidation reactor is 44.2-1270.7Nm ³ /h/m ² , preferably 82.17-644.9Nm ³ /h/m ² .

According to one aspect of the present invention, the operating linear velocity of the reactor in step (3-1) is generally 0.04-0.18 m/s, preferably 0.05-0.15 m/s or 0.05-0.15 m/s.

According to one aspect of the present invention, the operating linear velocity of the reactor in step (3-2) is generally 0.04-0.32 m/s, preferably 0.05-0.2 m/s or 0.04-0.17 m/s.

According to an aspect of the present invention, the expected technical effect of the present invention is more excellent From the point of view, the reactor operating linear velocity of the preferred step (3-1) and the reactor operating linear velocity of the step (3-2) are respectively 0.04-0.18m/s and 0.04-0.32m/s, preferably respectively 0.05-0.15m/s and 0.05-0.2m/s, or 0.05-0.15m/s and 0.04-0.17m/s respectively.

According to an aspect of the present invention, the subsequent step starts after the step (3-2) is carried out for 2-30 minutes. Here, as the subsequent step, for example, the step (4) can be cited. Preferably, the subsequent step starts after the step (3-2) is carried out for 5-25 minutes.

According to an aspect of the present invention, the elapsed time from the start of step (3-1) to the end of step (3-2) is generally 2-50 minutes, preferably 8-43 minutes.

According to an aspect of the present invention, the step (4) starts after the step (3) is carried out for 2-50 minutes. Preferably, the step (4) starts after the step (3) is carried out for 8-43 minutes.

According to an aspect of the present invention, in the step (4), the input amounts of the oxygen-containing gas, ammonia gas and the ammoxidation substrate into the ammoxidation reactor are adjusted to respective predetermined values. If by other steps before the step (4), such as the step (3) or the step (3-2), the oxygen-containing gas, ammonia gas and the ammoxidation substrate have been injected into the ammoxidation reactor respectively The input amount is adjusted to respective predetermined values, then this step (4) can be omitted and becomes an optional step. However, from the viewpoint of operational safety, it is preferable to have this step (4).

According to an aspect of the present invention, in the step (4), the temperature of the catalyst bed is 400-550°C or 400-440°C, preferably 400-440°C or 425-440°C. In order to prevent the temperature from being too high, during the step (4), sometimes a certain number of cooling coils need to be synchronously put in to control the temperature of the catalyst bed.

According to one aspect of the present invention, in the step (4), the pressure (gauge pressure) in the ammoxidation reactor is generally 0.030-0.060MPa, preferably 0.035-0.055MPa, but sometimes it is not limited thereto .

According to one aspect of the present invention, in the step (4), the predetermined input amount of the ammoxidation substrate (especially propylene) is 110-160Nm ³ /h/m ² , preferably 117-143Nm ³ /h/ m ² . For this reason, the input amount of the ammonia oxidation substrate can be adjusted to the predetermined value according to any means known in the art. For example, such as by changing the flow regulating device (such as valve, flow meter or orifice, etc.) on the pipeline used to transport the ammonia oxidation substrate into the ammonia oxidation reactor, thereby changing the input. In addition, as the adjustment method, such as increasing gradually (such as divided into multiple times, multi-steps or continuously) from the initial input amount to a corresponding predetermined value.

According to an aspect of the present invention, in the step (4), the predetermined input amount of ammonia gas is 120-230Nm ³ /h/m ² , preferably 125-185Nm ³ /h/m ² . For this reason, the input amount of ammonia can be adjusted to the predetermined value according to any manner known in the art. For example, such as changing the flow regulating device (such as valve, flow meter or orifice plate, etc.) on the pipeline used to transport ammonia gas into the ammoxidation reactor, thereby changing the input amount . In addition, as the adjustment method, such as increasing gradually (such as divided into multiple times, multi-steps or continuously) from the initial input amount to a corresponding predetermined value.

According to one aspect of the present invention, in the step (4), the predetermined input amount of the oxygen-containing gas (especially air) is 600-1600Nm ³ /h/m ² , preferably 1000-1500Nm ³ /h/ m ² or 1050-1400Nm ³ /h/m ² . For this purpose, the input amount of the oxygen-containing gas can be adjusted to the predetermined value according to any means known in the art. For example, such as by changing the flow regulating device (such as valve, flow meter or orifice, etc.) input. In addition, as the adjustment method, such as increasing gradually (such as divided into multiple times, multi-steps or continuously) from the initial input amount to a corresponding predetermined value.

According to an aspect of the present invention, in the step (4), the operating linear velocity of the reactor is generally 0.5-1.2 m/s, preferably 0.65-0.95 m/s.

According to an aspect of the present invention, the starting method is ended after the step (4) is performed for 5-30 minutes. Preferably, the starting method is ended after the step (4) is performed for 6-25 minutes.

According to one aspect of the present invention, from the perspective of the expected technical effect of the present invention being more excellent, preferably, the reactor operating linear velocity of the step (1), the reactor operating linear velocity of the step (2), the The reactor operating linear velocity of step (3) and the reactor operating linear velocity of the step (4) are respectively 0.03-0.15m/s, 0.04-0.18m/s, 0.04-0.32m/s and 0.5-1.2m/s s is preferably 0.03-0.1m/s, 0.05-0.15m/s, 0.05-0.20m/s (or 0.04-0.17m/s) and 0.65-0.95m/s respectively.

According to an aspect of the present invention, the elapsed time (that is, the starting time of the starting method) from the starting moment of the step (2) to the ending moment of the starting method is generally 10-100min, preferably 20-60min, more preferably Preferably 20-50min.

According to one aspect of the present invention, through some operating methods of temperature regulation and pressure regulation, parameters such as reaction temperature, reaction pressure, and operating line speed can reach the set target process parameters. For example, the reaction temperature can be adjusted by increasing or decreasing the number of cooling coils . For new catalysts, the ability of the catalyst to burn ammonia is relatively strong, and the catalyst needs to be acclimatized. When the device using the new catalyst is started for the first time, the operating load during the acclimatization period is best to operate at 70-95% of the full load, preferably 80-90%. For the balanced catalyst, the device start-up is not affected by this, and it can be operated within the range of 70-110% of the device's full load.

According to an aspect of the present invention, in the starting method, each step is closely connected with each other and operates continuously (that is, there is no intermediate pause or pause operation between different steps).

Example

The present invention will be described in further detail below using examples, but the present invention is not limited to these examples.

In the following examples and comparative examples, air is used as the heating medium and one of the raw materials for the ammoxidation reaction, but the present invention is not limited thereto. In addition, as an example, the temperature of the heating medium is 370-400° C., but the present invention is not limited thereto.

Example 1

The diameter of the fluidized bed reactor is 5.1 meters, and the height of the catalyst bed is 6.5 meters. The catalyst is a Mo-V series acrylonitrile fluidized bed catalyst (SANC series, manufactured by Sinopec Shanghai Petrochemical Research Institute). 98% by weight) to absorb unreacted ammonia in the reaction tail gas.

The starting method is as follows: 1. The reaction pressure is 0.3kg/cm ² , the air input volume is adjusted to 100Nm ³ /h/m ² , or the operating linear velocity of the reactor is adjusted to 0.057m/s, so that the temperature of the catalyst bed in the reactor reaches 380 ℃. 2. Adjust the ammonia gas flowmeter twice, the first time control the input amount of ammonia gas at 150Nm ³ /h, stabilize for 1.5min, control the input amount of ammonia gas to 372Nm ³ /h again, and adjust the operating line speed of the reactor to 0.068m/h s, the whole operation lasted 12min. 3 The content of molecular oxygen in the reaction tail gas is about 7.2% by volume. Propane is introduced into the reactor, the input amount of propane is controlled to 81Nm ³ /h, and the operating line speed of the reactor is adjusted to 0.07m/s. The whole operation lasts 4 minutes. 4 The molecular oxygen content in the reaction tail gas is 1.5% by volume, and the air flowmeter and the propane flowmeter are adjusted synchronously. The air input volume is controlled to 2753Nm ³ /h, the propane input volume is controlled to 286Nm ³ /h, and the operating line speed of the reactor is adjusted to 0.1m/s, the whole operation lasted 6min. 5. Adjust the propane, ammonia, and air flow meters until the input of propane is 2500Nm ³ /h, the input of ammonia is 3250Nm ³ /h, and the input of air is 24000Nm ³ /h, and the operating line speed of the reactor is adjusted to 0.78m/s , the whole operation lasted 12min. In each of the above steps, the reaction temperature can be controlled by adjusting the number of hot water withdrawal pipes put into use as required. The reaction temperature is 440°C, the reaction pressure (gauge pressure) is 0.050MPa, the start-up time of the start-up method is 34 minutes, the total consumption of ammonia is 786Nm ³ , the total consumption of propane is 534Nm ³ , and the total consumption of sulfuric acid is 172Kg.

Example 2

The diameter of the fluidized bed reactor is 2.8 meters, and the height of the catalyst bed is 5 meters. The catalyst is a Mo-Fe series hydrocyanic acid fluidized bed catalyst (SANC series, manufactured by Sinopec Shanghai Petrochemical Research Institute), and the methanol is evaporated After the reactor and the superheater, it enters the reactor in the form of gas phase, and the input amount is measured by a volumetric meter, and the unreacted ammonia in the reaction tail gas is absorbed with sulfuric acid (concentration 98% by weight).

The starting method is as follows: 1. The reaction pressure is 0.25kg/cm ² , the air input volume is adjusted to 162Nm ³ /h/m ² , or the operating line speed of the reactor is adjusted to 0.095m/s, so that the temperature of the catalyst bed in the reactor reaches 380 ℃. 2. Control the input amount of ammonia gas to 181Nm ³ /h, adjust the operating line speed of the reactor to 0.11m/s, and the whole operation lasts for 10min. 3. The content of molecular oxygen in the reaction tail gas is about 7.5% by volume. Methanol is introduced into the reactor, the amount of methanol input is controlled to 40Nm ³ /h, and the operating line speed of the reactor is adjusted to 0.12m/s. The entire operation lasts 3 minutes. 4 The content of molecular oxygen in the reaction tail gas is 1.5% by volume, and the air flowmeter and the methanol flowmeter are adjusted synchronously. The air input volume is controlled to 1515Nm ³ /h, the methanol input volume is controlled to 202Nm ³ /h, and the operating line speed of the reactor is adjusted to 0.17m/s, the whole operation lasted 6min. 5. Adjust the methanol, ammonia, and air flowmeters until the input amount of methanol is 800Nm ³ /h, the input amount of ammonia gas is 720Nm ³ /h, and the input amount of air is 6000Nm ³ /h, and the operating line speed of the reactor is adjusted to 0.66m/s , the whole operation lasted 12min. In each of the above steps, the reaction temperature can be controlled by adjusting the number of hot water withdrawal pipes put into use as required. The reaction temperature is 440°C, the reaction pressure (gauge pressure) is 0.050MPa, the start-up time of the start-up method is 30 minutes, the total consumption of ammonia is 198Nm ³ , the total consumption of methanol is 255kg, and the total consumption of sulfuric acid is 43Kg.

Example 3

The diameter of the fluidized bed reactor is 2.8 meters, and the height of the catalyst bed is 6.5 meters. The catalyst is a Mo-Bi acetonitrile fluidized bed catalyst (MB series, manufactured by Sinopec Shanghai Petrochemical Research Institute), and the acetic acid is passed through the evaporator and After the superheater, it enters the reactor in the form of a gas phase, and the input amount is measured by a volume meter, and sulfuric acid (concentration 98% by weight) is used to absorb unreacted ammonia in the reaction tail gas.

The start-up method is as follows: 1. The reaction pressure is 0.3kg/cm ² , the air input volume is adjusted to 162Nm ³ /h/m ² , or the operating line speed of the reactor is adjusted to 0.091m/s, so that the temperature of the catalyst bed in the reactor reaches 380 ℃. 2. Control the input amount of ammonia gas to 200Nm ³ /h, adjust the operating line speed of the reactor to 0.11m/s, and the whole operation lasts for 14min. 3. The content of molecular oxygen in the reaction tail gas is about 7.5% by volume. Acetic acid is introduced into the reactor, the amount of acetic acid input is controlled to 44Nm ³ /h, and the operating line speed of the reactor is adjusted to 0.12m/s. The entire operation lasts 5 minutes. 4 The molecular oxygen content in the reaction tail gas is 1.5% by volume, and the air flow meter and the acetic acid flow meter are adjusted synchronously. The air input volume is controlled to 625Nm ³ /h, the acetic acid input volume is controlled to 125Nm ³ /h, and the operating line speed of the reactor is adjusted to 0.13m/s, the whole operation lasted 5min. 5. Adjust the acetic acid, ammonia, and air flow meters until the input volume of acetic acid is 800Nm ³ /h, the input volume of ammonia gas is 1280Nm ³ /h, and the input volume of air is 4000Nm ³ /h, and the operating line speed of the reactor is adjusted to 0.52m/s , the whole operation lasted 12min. In each of the above steps, the reaction temperature can be controlled by adjusting the number of hot water withdrawal pipes put into use as required. The reaction temperature is 400°C, the reaction pressure (gauge pressure) is 0.050MPa, the startup time of the start-up method is 36 minutes, the total consumption of ammonia is 336Nm ³ , the total consumption of acetic acid is 466kg, and the total consumption of sulfuric acid is 73Kg.

Example 4

The diameter of the fluidized bed reactor is 5.1 meters, and the height of the catalyst bed is 7.3 meters. The catalyst is a Mo-Bi series benzonitrile fluidized bed catalyst (BN series, manufactured by Sinopec Shanghai Petrochemical Research Institute), and the toluene is evaporated After the reactor and the superheater, it enters the reactor in the form of gas phase, and the input amount is measured by a volumetric meter, and the unreacted ammonia in the reaction tail gas is absorbed with sulfuric acid (concentration 98% by weight).

The starting method is as follows: 1. The reaction pressure is 0.3kg/cm ² , the air input volume is adjusted to 100Nm ³ /h/m ² , or the operating linear velocity of the reactor is adjusted to 0.057m/s, so that the temperature of the catalyst bed in the reactor reaches 380 ℃. 2. Adjust the ammonia gas flowmeter twice, the first time control the input amount of ammonia gas at 150Nm ³ /h, stabilize for 1.5min, control the input amount of ammonia gas to 372Nm ³ /h again, and adjust the operating line speed of the reactor to 0.068m/h s, the whole operation lasted 14min. 3. The content of molecular oxygen in the reaction tail gas is about 7.2% by volume. Toluene is introduced into the reactor, the amount of toluene input is controlled to 41Nm ³ /h, and the operating line speed of the reactor is adjusted to 0.07m/s. The entire operation lasts 5 minutes. 4 The molecular oxygen content in the reaction tail gas is 1.5% by volume, and the air flow meter and the toluene flow meter are adjusted synchronously. The air input volume is controlled to 2330Nm ³ /h, the toluene input volume is controlled to 93Nm ³ /h, and the operating line speed of the reactor is adjusted to 0.077m/s, the whole operation lasted 6min. 5. Adjust the toluene, ammonia, and air flowmeters until the input amount of toluene is 1000Nm ³ /h, the input amount of ammonia gas is 4000Nm ³ /h, and the input amount of air is 25000Nm ³ /h, and the operating line speed of the reactor is adjusted to 0.74m/s , the whole operation lasted 12min. In each of the above steps, the reaction temperature can be controlled by adjusting the number of hot water withdrawal pipes put into use as required. The reaction temperature is 400°C, the reaction pressure (gauge pressure) is 0.045MPa, the start-up time of the start-up method is 37 minutes, the total consumption of ammonia is 755Nm ³ , the total consumption of toluene is 2208kg, and the total consumption of sulfuric acid is 165Kg.

Example 5

The diameter of the fluidized bed reactor is 7.5 meters, and the height of the catalyst bed is 7 meters. The catalyst is a fresh Mo-Bi system acrylonitrile catalyst (SANC series, manufactured by Sinopec Shanghai Petrochemical Research Institute). Sulfuric acid (concentration 98 % by weight) to absorb unreacted ammonia in the reaction tail gas.

The starting method is as follows: 1. The reaction pressure is 0.3kg/cm ² , the air input volume is adjusted to 54Nm ³ /h/m ² , or the operating linear velocity of the reactor is adjusted to 0.030m/s, so that the temperature of the catalyst bed in the reactor reaches 370 ℃. 2. Adjust the ammonia gas flowmeter twice, the first time control the input amount of ammonia gas at 150Nm ³ /h, stabilize for 1.5min, control the input amount of ammonia gas to 480Nm ³ /h again, and adjust the operating line speed of the reactor to 0.040m/h s, the whole operation lasted 10min. 3. The content of molecular oxygen in the reaction tail gas is about 7.2% by volume. Introduce propylene into the reactor, adjust the propylene flow meter, control the input amount of propylene to 104Nm ³ /h, and adjust the operating line speed of the reactor to 0.040m/s. The whole operation lasted 3min. 4 The content of molecular oxygen in the reaction tail gas is 1.5% by volume, and the air flow meter and the propylene flow meter are adjusted synchronously. The air input volume is controlled to be 3686Nm ³ /h, the propylene input volume is controlled to be 384Nm ³ /h, and the operating line speed of the reactor is adjusted to be 0.058m/s, the whole operation lasted 4min. 5. Adjust the propylene, ammonia, and air flow meters until the input of propylene is 4861Nm ³ /h, the input of ammonia is 6076Nm ³ /h, and the input of air is 46665Nm ³ /h, and the operating line speed of the reactor is adjusted to 0.7m/s , the whole operation lasted 10min. In each of the above steps, the reaction temperature can be controlled by adjusting the number of hot water withdrawal pipes put into use as required. The reaction temperature is 425°C, the reaction pressure (gauge pressure) is 0.045MPa, the start-up time of the start-up method is 27 minutes, the total consumption of ammonia is 1092Nm ³ , the total consumption of propylene is 835Nm ³ , and the total consumption of sulfuric acid is 239Kg.

Example 6

The diameter of the fluidized bed reactor is 7.5 meters, and the height of the catalyst bed is 7 meters. The catalyst is a balanced Mo-Bi system acrylonitrile catalyst (SANC series, manufactured by Sinopec Shanghai Petrochemical Research Institute). Sulfuric acid (concentration 98 % by weight) to absorb unreacted ammonia in the reaction tail gas.

The start-up method is as follows: 1. The reaction pressure is 0.3kg/cm ² , the air input volume is adjusted to 59Nm ³ /h/m ² , or the operating linear velocity of the reactor is adjusted to 0.034m/s, so that the temperature of the catalyst bed in the reactor reaches 390 ℃. 2. Adjust the ammonia gas flowmeter twice, the first time control the input amount of ammonia gas at 150Nm ³ /h, stabilize for 1.5min, control the input amount of ammonia gas again to 577Nm ³ /h, adjust the operating line speed of the reactor to 0.041m/s , the whole operation lasted 11min. 3 The content of molecular oxygen in the reaction tail gas is about 7.3% by volume. Propylene is introduced into the reactor, and the propylene flow meter is adjusted to control the input amount of propylene to 137Nm ³ /h, and the operating line speed of the reactor is adjusted to 0.044m/s. The operation lasted 4 minutes. 4 The molecular oxygen content in the reaction tail gas is 2.0% by volume, and the air flow meter and the propylene flow meter are adjusted synchronously. The air input volume is controlled to be 4620Nm ³ /h, the propylene input volume is controlled to be 480Nm ³ /h, and the operating line speed of the reactor is adjusted to be 0.074m/s, the whole operation lasted 5min. 5. Adjust the propylene, ammonia, and air flow meters until the input of propylene is 5684Nm ³ /h, the input of ammonia is 7390Nm ³ /h, and the input of air is 54000Nm ³ /h, and the operating line speed of the reactor is adjusted to 0.81m/s , the whole operation lasted 12min. In each of the above steps, the reaction temperature can be controlled by adjusting the number of hot water withdrawal pipes put into use as required. The reaction temperature is 435°C, the reaction pressure (gauge pressure) is 0.045MPa, the startup time of the start-up method is 32 minutes, the total consumption of ammonia is 1642Nm ³ , the total consumption of propylene is 1160Nm ³ , and the total consumption of sulfuric acid is 346Kg.

Example 7

It is basically the same as Example 6, except for the following changes.

The start-up method is as follows: 1. The reaction pressure is 0.3kg/cm ² , the air input volume is adjusted to 158Nm ³ /h/m ² , or the operating line speed of the reactor is adjusted to 0.091m/s, so that the temperature of the catalyst bed in the reactor reaches 390 ℃. 2. Adjust the ammonia gas flowmeter twice, the first time control the input amount of ammonia gas at 180Nm ³ /h, stabilize for 1.5min, control the input amount of ammonia gas again to 1166Nm ³ /h, adjust the operating line speed of the reactor to 0.11m/s , the whole operation lasted 9min. 3. The content of molecular oxygen in the reaction tail gas is about 7.5% by volume. Introduce propylene into the reactor, adjust the propylene flowmeter twice, and control the propylene input at 100Nm ³ /h for the first time, and stabilize it for 1.0min. Control to 259Nm ³ /h, adjust the operating line speed of the reactor to 0.11m/s, and the whole operation lasts 6min. 4 The content of molecular oxygen in the reaction tail gas is 1.8% by volume. Synchronously adjust the air flow meter and the propylene flow meter to control the air input amount to 8960Nm ³ /h and the propylene input amount to 933Nm ³ /h respectively, and adjust the reactor operating line The speed is 0.14m/s, and the whole operation lasts 6min. 5. Adjust the propylene, ammonia, and air flow meters until the input of propylene is 5684Nm ³ /h, the input of ammonia is 7105Nm ³ /h, and the input of air is 54570Nm ³ /h, and the operating line speed of the reactor is adjusted to 0.81m/s , the whole operation lasted 15min. In each of the above steps, the reaction temperature can be controlled by adjusting the number of hot water withdrawal pipes put into use as required. The reaction temperature is 430°C, the reaction pressure (gauge pressure) is 0.045MPa, the startup time of the start-up method is 36 minutes, the total consumption of ammonia is 2150Nm ³ , the total consumption of propylene is 1520Nm ³ , and the total consumption of sulfuric acid is 470Kg.

Example 8

It is basically the same as Example 5, except for the following changes.

The starting method is as follows: 1. The reaction pressure is 0.3kg/cm ² , the air input volume is adjusted to 181Nm ³ /h/m ² , or the operating line speed of the reactor is adjusted to 0.1m/s, so that the temperature of the catalyst bed in the reactor reaches 370 ℃. 2. Adjust the ammonia gas flowmeter twice, the first time control the input amount of ammonia gas at 180Nm ³ /h, stabilize for 1.5min, control the input amount of ammonia gas again to 1595Nm ³ /h, adjust the operating line speed of the reactor to 0.12m/s , the whole operation lasted 14min. 3. The content of molecular oxygen in the reaction tail gas is about 7.5% by volume. Introduce propylene into the reactor, adjust the propylene flow meter, control the input amount of propylene to 354Nm ³ /h, and adjust the operating line speed of the reactor to 0.13m/s. The operation lasted 7 minutes. 4 The content of molecular oxygen in the reaction tail gas is 1.8% by volume. Synchronously adjust the air flow meter and the propylene flow meter to control the air input volume to 11780Nm ³ /h and the propylene input volume to 1227Nm ³ /h respectively. Adjust the reactor operating line The speed is 0.20m/s, and the whole operation lasts 7min. 5. Adjust the propylene, ammonia, and air flow meters until the input of propylene is 5684Nm ³ /h, the input of ammonia is 7105Nm ³ /h, and the input of air is 54570Nm ³ /h, and the operating line speed of the reactor is adjusted to 0.81m/s , the whole operation lasted 15min. In each of the above steps, the reaction temperature can be controlled by adjusting the number of hot water withdrawal pipes put into use as required. The reaction temperature is 430°C, the reaction pressure (gauge pressure) is 0.045MPa, the start-up time of the start-up method is 43 minutes, the total consumption of ammonia is 2510Nm ³ , the total consumption of propylene is 1594Nm ³ , and the total consumption of sulfuric acid is 542Kg.

Comparative example 1

It is basically the same as Example 5, except for the following changes.

The starting method is as follows: 1. The reaction pressure is 0.3kg/cm ² , the air input volume is adjusted to 323Nm ³ /h/m ² , or the operating linear velocity of the reactor is adjusted to 0.18m/s, so that the temperature of the catalyst bed in the reactor reaches 370 ℃. 2. Adjust the ammonia gas flowmeter twice. For the first time, control the input amount of ammonia gas at 150Nm ³ /h, stabilize it for 1.5min, control the input amount of ammonia gas to 300Nm ³ /h again, and adjust the operating line speed of the reactor to 0.21m/h s, the whole operation lasted 10min. At the end of 2, the content of molecular oxygen in the reaction tail gas was 10.0% by volume, and there was a risk of exceeding the explosion limit of acrylonitrile, so that the start-up process could not be continued.

Comparative example 2

It is basically the same as Example 5, except for the following changes.

The start-up method is as follows: 1. The reaction pressure is 0.3kg/cm ² , the air input volume is adjusted to 543Nm ³ /h/m ² , or the operating linear velocity of the reactor is adjusted to 0.3m/s, so that the temperature of the catalyst bed in the reactor reaches 370 ℃. 2. Adjust the ammonia gas flowmeter twice. For the first time, control the input amount of ammonia gas at 300Nm ³ /h and stabilize it for 1.5 minutes. Then control the input amount of ammonia gas to 4800Nm ³ /h and adjust the operating line speed of the reactor to 0.38m/h s, the whole operation lasted 45min. 3. The content of molecular oxygen in the reaction tail gas is about 7.2% by volume. Introduce propylene into the reactor, adjust the propylene flowmeter twice, and control the input amount of propylene at 300Nm ³ /h for the first time, stabilize it for 1.0min, and then add propylene again The amount was controlled to 1043Nm ³ /h, and the operating linear velocity of the reactor was adjusted to 0.39m/s, and the entire operation lasted 21 minutes. 4 The molecular oxygen content in the reaction tail gas is 1.5% by volume, and the air flowmeter and the propylene flowmeter are adjusted synchronously. The air input volume is controlled to 36864Nm ³ /h, the propylene input volume is controlled to 3840Nm ³ /h, and the operating line speed of the reactor is adjusted to 0.58m/s, the whole operation lasted 28min. 5. Adjust the propylene, ammonia, and air flow meters until the input of propylene is 5680Nm ³ /h, the input of ammonia is 7100Nm ³ /h, and the input of air is 54570Nm ³ /h, and the operating line speed of the reactor is adjusted to 0.83m/s , the whole operation lasted 32min. In each of the above steps, the reaction temperature can be controlled by adjusting the number of hot water withdrawal pipes put into use as required. The reaction temperature is 425°C, the reaction pressure (gauge pressure) is 0.045MPa, the start-up time of the start-up method is 126 minutes, the total consumption of ammonia is 11200Nm ³ , the total consumption of propylene is 5000Nm ³ , and the total consumption of sulfuric acid is 2460Kg.

Claims (25)

A method for starting an ammoxidation reaction, comprising the following steps: (1) heating a catalyst bed in an ammoxidation reactor with an oxygen-containing gas, wherein the operating linear velocity of the reactor is 0.03-0.15m/s; (2) feeding the ammonia Continuously input ammonia into the oxidation reactor; (3) continuously input the ammonia oxidation substrate into the ammonia oxidation reactor; and (4) optionally, add the oxygen-containing gas, ammonia and the ammonia oxidation substrate to the ammonia oxidation The respective inputs in the reactor are adjusted to their respective predetermined values. The start-up method of Claim 1, wherein the ammoxidation reactor is a fluidized bed reactor, and/or, in the step (1), the operating linear velocity of the reactor is 0.03-0.1m/s, and/or , in the step (1), the input amount of the oxygen-containing gas into the ammoxidation reactor is 54-276Nm ³ /h/m ² . The start-up method as claimed in item 1 comprises the following steps: (1) utilizing oxygen-containing gas to heat the catalyst bed in the ammoxidation reactor; (2) continuously feeding ammonia into the ammoxidation reactor; (3) injecting ammonia into the ammoxidation reactor; The ammoxidation reactor continuously feeds the ammoxidation substrate; and (4) adjusts the input amounts of the oxygen-containing gas, ammonia gas and the ammoxidation substrate to the respective predetermined values in the ammoxidation reactor, wherein the steps ( 1) Reactor operating line speed, step (2) reactor operating line speed, step The reactor operating linear velocity of step (3) and the reactor operating linear velocity of step (4) are respectively 0.03-0.15m/s, 0.04-0.18m/s, 0.04-0.32m/s and 0.5-1.2m/s . As the starting method of claim item 3, wherein the reactor operating linear velocity of step (1), the reactor operating linear velocity of step (2), the reactor operating linear velocity of step (3) and the reactor operating of step (4) The line speeds are 0.03-0.1m/s, 0.05-0.15m/s, 0.05-0.20m/s and 0.65-0.95m/s respectively. The start-up method according to claim 3, wherein in the step (1), the input amount of the oxygen-containing gas into the ammoxidation reactor is 54-276Nm ³ /h/m ² . The start-up method according to claim 3, wherein in the step (1), the input amount of the oxygen-containing gas into the ammoxidation reactor is 54-182Nm ³ /h/m ² . The starting method according to claim 1, wherein the ammoxidation substrate is selected from at least one of propane, isobutane, propylene, isobutylene, methanol, ethanol, propanol, dimethyl ether, methyl ethyl ether, acetic acid and methyl acetate. The starting method of claim 1, wherein, in the step (1), the temperature of the catalyst bed is 360-500°C, and/or, in the step (2), the temperature of the catalyst bed is 390°C -440°C, and/or, in the step (3), the temperature of the catalyst bed is 400-440°C, and/or, in the step (4), the temperature of the catalyst bed is 400-550 ℃. The starting method of claim 1, wherein, in the step (1), the temperature of the catalyst bed is 380-390°C, and/or, in the step (2), the temperature of the catalyst bed is 400 -440°C, and/or, in the step (3), the temperature of the catalyst bed is 410-430°C, and/or, in the step (4), the temperature of the catalyst bed is 425-440°C ℃. As the starting method of claim 1, wherein, the step (3) is started after the step (2) is carried out for 2-20 minutes, and/or, the step (4) is started after the step (3) is carried out for 2-50 minutes, And/or, the starting method is ended after the step (4) is carried out for 5-30 minutes, and/or, the elapsed time from the starting time of the step (2) to the ending time of the starting method is 10-100 minutes. The starting method of claim 1, wherein the step (3) is started after the step (2) is carried out for 5-18 minutes, and/or, the step (4) is started after the step (3) is carried out for 8-43 minutes, And/or, the starting method is ended after the step (4) is carried out for 6-25 minutes, and/or, the elapsed time from the starting time of the step (2) to the ending time of the starting method is 20-50 minutes. The start-up method of claim 1, wherein, in the step (2), the input amount of ammonia gas into the ammoxidation reactor target value is 7.5-110 Nm ³ /h/m ² , and the input of the ammonia gas The ratio of the amount target value to the input amount of the oxygen-containing gas is 1:2.5-7, and/or, in the step (3), the input amount target value of the ammoxidation substrate in the ammoxidation reactor is 5.2-110.5Nm ³ /h/m ² , and/or, in the step (4), the predetermined input amount of the ammonia oxidation substrate is 110-160Nm ³ /h/m ² , and the predetermined input amount of ammonia gas It is 120-230Nm ³ /h/m ² , and the input amount of the oxygen-containing gas is predetermined to be 600-1600Nm ³ /h/m ² . The start-up method according to claim 1, wherein, in the step (2), the target value of the input amount of ammonia gas into the ammoxidation reactor is 7.5-45.6Nm ³ /h/m ² , and the input of the ammonia gas The ratio of the amount target value to the input amount of the oxygen-containing gas is 1:4-7, and/or, in the step (3), the input amount target value of the ammoxidation substrate into the ammoxidation reactor is 9.13-65.8Nm ³ /h/m ² , and/or, in the step (4), the predetermined input amount of the ammonia oxidation substrate is 117-143Nm ³ /h/m ² , and the predetermined input amount of ammonia gas It is 125-185Nm ³ /h/m ² , and the input amount of the oxygen-containing gas is predetermined to be 1050-1400Nm ³ /h/m ² . The start-up method as in claim 1, wherein the step (3) comprises the following steps: (3-1) keeping the input amount of the ammonia gas into the ammoxidation reactor substantially constant, and starting to input into the ammoxidation reactor the ammoxidation substrate; and (3-2) increasing the respective inputs of the oxygen-containing gas and the ammoxidation substrate into the ammoxidation reactor, Wherein the reactor operating linear velocity of step (3-1) and the reactor operating linear velocity of step (3-2) are respectively 0.04-0.18m/s and 0.04-0.32m/s. The starting method of claim 14, wherein the reactor operating linear velocity in step (3-1) and the reactor operating linear velocity in step (3-2) are 0.05-0.15m/s and 0.04-0.17m/s respectively. The starting method of claim 14, wherein the step (3-2) is started after the step (3-1) is carried out for 2-20 minutes, and/or, the step (3-2) is started after the step (3-2) is carried out for 2-30 minutes The step (4), and/or, the elapsed time from the start of the step (3-1) to the end of the step (3-2) is 2-50 minutes. The starting method of claim 14, wherein the step (3-2) starts after the step (3-1) is carried out for 3-18 minutes, and/or, starts after the step (3-2) is carried out for 5-25 minutes The step (4), and/or, the elapsed time from the start of the step (3-1) to the end of the step (3-2) is 8-43 minutes. The starting method of claim 14, wherein, in the step (3-1), the temperature of the catalyst bed is 400-440°C, and/or, in the step (3-2), the catalyst bed The temperature is 400-550°C. The starting method of claim 14, wherein, In the step (3-1), the temperature of the catalyst bed is 400-415°C, and/or, in the step (3-2), the temperature of the catalyst bed is 425-440°C. The starting method according to claim 14, wherein, in the step (3-1), the amount of input of the ammoxidation substrate into the ammoxidation reactor is such that the ammoxidation substrate and ammonia injected into the ammoxidation reactor The molar ratio of the gas reaches 1:4-7, and/or, in the step (3-2), increase the input amount of the oxygen-containing gas and the ammoxidation substrate into the ammoxidation reactor respectively, so that The molar ratio of the ammoxidation substrate and ammonia gas introduced into the ammoxidation reactor reaches 1:0.8 to 1:5, and makes the ratio of the ammoxidation substrate and the oxygen-containing gas introduced into the ammoxidation reactor The molar ratio reaches 1:4 to 1:30. The starting method according to claim 14, wherein, in the step (3-1), the amount of input of the ammoxidation substrate into the ammoxidation reactor is such that the ammoxidation substrate and ammonia injected into the ammoxidation reactor The molar ratio of the gas reaches 1:4.5-6.5, and/or, in this step (3-2), increase the respective input amounts of the oxygen-containing gas and the ammoxidation substrate in the ammoxidation reactor, so that The molar ratio of the ammoxidation substrate and ammonia gas introduced into the ammoxidation reactor reaches 1:1.05 to 1:1.3, and makes the ratio of the ammoxidation substrate and the oxygen-containing gas introduced into the ammoxidation reactor The molar ratio reaches 1:9 to 1:9.8. The start-up method according to claim 14, wherein, in the step (3-1), the input amount target value of the ammoxidation substrate into the ammoxidation reactor is 1.5-22.1Nm ³ /h/m ² , and/ Or, in the step (3-2), the input amount target value of the ammoxidation substrate into the ammoxidation reactor is 5.2-110.5Nm ³ /h/m ² , and the oxygen-containing gas into the ammoxidation reactor The input amount target value is 44.2-1270.7Nm ³ /h/m ² . The start-up method of Claim 14, wherein, in the step (3-1), the target value of the input amount of the ammoxidation substrate into the ammoxidation reactor is 2.74-13.8Nm ³ /h/m ² , and/ Or, in the step (3-2), the input amount target value of the ammoxidation substrate into the ammoxidation reactor is 9.13-65.8Nm ³ /h/m ² , and the oxygen-containing gas into the ammoxidation reactor The input amount target value is 82.17-644.9Nm ³ /h/m ² . The starting method of claim 1, 3 or 14, wherein, at the moment when the step (3) starts or when the step (3-1) starts, the content of molecular oxygen in the reaction tail gas is relative to the total amount of the reaction tail gas The volume is less than 7.5% by volume, and/or, at the moment when the step (3-2) starts, the content of molecular oxygen in the reaction tail gas is less than 2% by volume relative to the total volume of the reaction tail gas. The starting method of claim 1, 3 or 14, wherein, at the moment when the step (3) starts or when the step (3-1) starts, the content of molecular oxygen in the reaction tail gas is relative to the total amount of the reaction tail gas The volume is 7-7.5% by volume, and/or, at the moment when the step (3-2) starts, the content of molecular oxygen in the reaction tail gas relative to the total volume of the reaction tail gas is 0.5-2% by volume.