JP2008043894A - Temperature control method for fluidized bed reactor - Google Patents

Abstract

A fluidized bed reactor used for a gas phase exothermic reaction is provided with a method capable of controlling the temperature more finely than before.
[MEANS FOR SOLVING PROBLEMS] (1) At least one temperature detection unit (15), (2) at least one heat removal pipe (6, 7) for regular use, (3) at least one heat removal pipe (8) for temperature adjustment. When performing the gas phase exothermic reaction using the fluidized bed reactor 1, the temperature is controlled by adjusting the heat removal capability of the heat removal pipe for fine temperature adjustment according to the difference between the temperature of the temperature detection unit and the set temperature. In the substantial adjustment range (0.0FS to 1.0FS), the average rate of change during the change from the capacity 10% (0.1FS) to the capacity 90% (0.9FS) is 0.1FS / min or more. Temperature control method for fluidized bed reactor characterized by

Description

  The present invention relates to a temperature control method for a fluidized bed reactor used for a gas phase exothermic reaction.

  In order to industrially produce monomers useful for the production of various synthetic resins and synthetic fibers by gas phase exothermic reaction, fluidized bed reactors are widely used. Typical examples of the gas phase exothermic reaction carried out industrially include a sequential oxidation reaction such as a partial oxidation reaction or an ammoxidation reaction in the presence of ammonia. In the sequential oxidation reaction, the oxidation stability of the partial oxidation product, which is the target product, is generally not so great, so the sequential reaction of the target product proceeds as the reaction progresses, that is, the reaction conversion rate increases. However, the increase in the complete oxidation product tends to lower the selectivity of the target product. Therefore, the yield of the target product obtained as the product of the conversion rate and the selectivity has a maximum value at a certain conversion rate. For example, Non-Patent Document 1 discloses that acrylonitrile production by propylene ammoxidation usually has a maximum value of 85 to 95%. For this reason, in order to produce the target product more advantageously economically, it is extremely important to control the conversion rate of the reaction within a preferable range. Of course, this is not limited to the oxidation reaction, but may be considered to hold for a general gas phase exothermic reaction.

Here, the conversion rate of the reaction depends on the activity of the catalyst, and the conversion rate increases as the catalyst activity increases. Further, the catalytic activity depends on the reaction temperature, and the catalyst activity generally increases as the reaction temperature increases, except for exceptions such as enzyme reactions.
Also, for example, in the case of an oxidation reaction, it is clear that a complete oxidation reactant (eg, CO ₂ ) is more stable when comparing the product energy of a partial oxidation product and a complete oxidation reactant. Obviously, if the contribution rate of the oxidation reaction increases, the calorific value of the entire reaction system increases. This may also be considered to hold for general gas phase exothermic reactions.

  Therefore, in the gas phase exothermic reaction, if the reaction temperature rises for some reason, 1) the activity of the catalyst increases as the temperature increases, and 2) the conversion rate of the reaction increases as the activity increases, and successive reactions occur. 3) As the amount of the raw material that is actually reacted increases, and the contribution of more stable products increases as the successive reactions progress, the calorific value per unit time of the entire reaction system increases. 4) As a result, the reaction temperature tends to increase, and the circulation behavior tends to be exhibited. Of course, when the reaction temperature is lowered, the reverse circulation behavior is exhibited as well, and in either case, the temperature diverges locally, causing a temperature distribution in the reactor. In a more extreme case, the temperature of the entire reactor will diverge, leading to thermal runaway of the reactor and reaction stoppage. Therefore, it is extremely important to precisely control the reaction temperature in order to produce the target product more economically advantageously and to continue the reaction stably.

  On the other hand, one of the advantages of fluidized bed reactors is that heat transfer in the reactor is faster and the reaction temperature is relatively easy to control compared to other reactor types, for example, fixed bed reactors. Can be given. When the gas phase exothermic reaction is performed using the fluidized bed reactor, the temperature of the reactor is controlled, for example, as disclosed in Patent Document 1 and Non-Patent Document 2, for example, a vertical tube in the fluidized bed. The most common method is to collect a reaction heat by arranging a group and passing a fluid as a cooling medium through it to use as a heat removal tube. At this time, as disclosed in, for example, Patent Document 2 and Patent Document 3, attempts have been made to arrange heat removal tubes in the upper and lower portions of the reactor, respectively, and control them at different temperatures.

Further, as a method for controlling the reactor temperature based on the temperature detected by the temperature detector installed in the reactor, for example, Patent Document 4 discloses that at least one heat removal pipe has a cooling medium at a variable speed. And a method for adjusting the temperature of the fluidized bed reactor capable of controlling the temperature by adjusting the flow rate of the fluidized bed reactor. Patent Document 5 discloses a method for controlling the temperature by adjusting the flow rate of the liquid mixed in the vapor having a substantially constant flow rate when supplying a mixture of the liquid and the vapor as the cooling medium. is doing.
However, in view of the importance of temperature control in the gas phase oxidation reaction described above, particularly stable temperature control, the temperature control according to these prior arts is not sufficient, and the establishment of a method that enables more precise temperature control. Was demanded.

US Pat. No. 3,156,538 Japanese Patent Laid-Open No. 2-19370 U.S. Pat. No. 3,080,382 WO95 / 21692 publication US Pat. No. 2,697,334 Tetsuo Tanaka, “Advances in Acrylonitrile Manufacturing Technology”, JCIA Monthly Report, Japan Chemical Industry Association, October 1971, pp. 551-561 Edited by Kenji Hashimoto, Industrial Reaction Equipment, Bafukan, February 1984, pp. 168-177

  It is an object of the present invention to provide a temperature control method that is improved over the prior art for a fluidized bed reactor used for a gas phase exothermic reaction.

  As a result of intensive studies on the fluidized bed reactor used for the gas phase exothermic reaction, the reactor temperature can be controlled more precisely. When controlling the temperature within a certain range, it was found that the reactor temperature can be controlled more precisely than before by keeping the adjustment speed of the heat removal tube capacity within the certain range, and the present invention has been completed.

That is, the present invention is as follows.
(1) 1) at least one temperature detection unit, 2) at least one heat removal pipe to be used regularly, 3) gas phase using a fluidized bed reactor having at least one temperature adjustment heat removal pipe In carrying out the exothermic reaction, when the temperature is controlled by adjusting the heat removal capability of the heat removal pipe for temperature adjustment according to the difference between the temperature of the temperature detection unit and the set temperature, a substantial adjustment range (0.0FS to 1.0FS), the average rate of change during a change from a capacity of 10% (0.1FS) to a capacity of 90% (0.9FS) is 0.1 to 6.0FS / min. Temperature control method for fluidized bed reactor.
(2) In the temperature range for carrying out the reaction, the total reaction heat including side reactions is 2500 kJ / mol (raw material) or less, and the partial differential coefficient related to the temperature of the total reaction heat is 40 kJ / mol ( The temperature control method for a fluidized bed reactor according to (1) above, wherein the raw material is equal to or less than K.

(3) The fluidized bed according to (1) or (2), wherein the reaction to be performed is a gas phase ammoxidation reaction using propane and / or propylene as a raw material, and the product of the reaction is acrylonitrile. Reactor temperature control method.
(4) The reaction to be carried out is a gas phase oxidation reaction using at least one selected from n-butane, 1-butene, 2-butene, butadiene, and benzene, and the product of the reaction is maleic anhydride The temperature control method for a fluidized bed reactor according to (1) or (2) above.

(5) The reaction to be carried out is a gas phase ammoxidation reaction using i-butene and / or i-butane as a raw material, and the product of the reaction is methacrylonitrile, (1), (2 ) Temperature control method for fluidized bed reactors.
(6) The reaction to be carried out is a gas phase oxidation reaction using o-xylene and / or naphthalene as a raw material, and the product of the reaction is phthalic anhydride, described in (1) and (2) above Temperature control method for a fluidized bed reactor.

(7) The reaction to be carried out is a gas phase oxidation reaction using phenol and methanol as raw materials, and the product of the reaction is 2,6-xylenol and / or o-cresol, (1), The temperature control method of the fluidized bed reactor as described in 2).
(8) The reaction to be carried out is a gas phase ammoxidation reaction using methane and / or methanol as a raw material, and the product of the reaction is hydrocyanic acid (HCN), as described in (1) and (2) above Temperature control method for a fluidized bed reactor.
(9) The reaction to be carried out is a gas phase ammoxidation reaction using at least one selected from ethane, ethene, and ethanol as a raw material, and the product of the reaction is acetonitrile, ) Temperature control method for fluidized bed reactors.

  The present invention makes it possible to control the temperature of the fluidized bed reactor used for the gas phase exothermic reaction more finely than before.

  The present invention will be described in more detail. In order to precisely control the temperature of the fluidized bed in which the gas phase exothermic reaction is performed, the amount of generated heat is kept as stable as possible and the heat in the fluidized bed is maintained. It is desirable that the movement be made promptly. In order to keep the amount of generated heat stable, it is desirable to keep the reaction conditions such as the feed rate of the raw material and the reaction pressure as constant as possible so that the reaction can be performed stably. In addition, in order to quickly move the heat in the fluidized bed, it is necessary to keep the fluidized state of the fluidized bed good. In general, it is known that the fluidized state of a fluidized bed is governed by gas flow rate (superficial velocity), catalyst particle size, and the like. In the practice of the present invention, there is no particular limitation as long as it is in the range of the gas flow rate that can keep the fluidized state of the fluidized bed good. Further, the catalyst used in the practice of the present invention can be used as it is as long as it is a catalyst used in a normal fluidized bed reactor, but the weight average particle diameter is 20 to 100 μm, preferably 30 to 80 μm, and more preferably. The content of fine powder (so-called good fraction) having a particle size of 40 to 60 μm and a particle size of 44 μm or less is preferably 10 to 70% by weight, and is classified as A particles in the Geldart powder classification map.

  The fluidized bed reactor used in the present invention has a gas phase exothermic reaction, for example, production of acrylonitrile by a gas phase ammoxidation reaction using propane and / or propylene as a raw material, n-butane, 1-butene, 2-butene, butadiene, Production of maleic anhydride by gas phase oxidation reaction using one or more selected from benzene as raw material, Production of methacrylonitrile by gas phase ammoxidation reaction using i-butene and / or i-butane as raw material, o-xylene And / or production of phthalic anhydride by gas phase oxidation reaction using naphthalene as raw material, production of 2,6-xylenol and / or o-cresol by gas phase oxidation reaction using phenol and methanol as raw materials, methane and / or methanol Industrial production of hydrogen cyanide (HCN) by gas phase ammoxidation reaction Those that are often used in making in view. In such a fluidized bed reactor, the catalyst particles are generally kept fluidized by the upward flow of gas introduced from the lower part of the reactor, but the present invention is limited to the upward flow type. It may be a downflow type or another method.

The present invention is applied to a fluidized bed reactor that performs a gas phase exothermic reaction. The reaction heat varies depending on the reaction. For example, the reaction heat for producing acrylonitrile from propylene and ammonia is 520 kJ / mol (propylene), and the reaction heat for producing acrylonitrile from propane and ammonia is 637 kJ / mol (propane). However, the actual reaction is a simultaneous and sequential reaction, and CO ₂ , CO, and other by-products are generated. The total reaction heat including up to the side reaction can be determined in consideration of the contribution rate of each reaction (the yield of each product).

For example, the reaction heat of propane combustion to produce CO ₂ and water or CO and water is 2043 kJ / mol (propane) and 1194 kJ / mol (propane) per 1 mol of propane, respectively. When 100 mol of propane was reacted with ammonia and oxygen, 80 mol of propane reacted (reaction rate 80%), 50 mol acrylonitrile (yield 50%), 60 mol CO ₂ (yield 20%), 30 mol CO 2 Assuming that (yield 10%) is produced, the total reaction heat under these conditions can be obtained as 637 × 0.5 + 2043 × 0.2 + 1194 × 0.1 = 846.5 (kJ / mol). . As is clear from the calculation process, the reaction heat as a whole varies depending on the reaction rate of the raw materials, the contribution rate of each concurrent reaction (product distribution), and the like, and thus depends on the reaction conditions. There is no particular restriction on the total reaction heat, but if it is excessive, the amount of heat to be removed will increase and control will be difficult, causing the temperature distribution in the reactor, and in extreme cases, it may cause thermal runaway of the reactor. From this point of view, it is preferable that the reaction heat as a whole be as small as possible when selecting the reaction conditions. Specifically, the reaction conditions may be selected so that it is 2500 kJ / mol (raw material) or less, preferably 2000 kJ / mol (raw material) or less per 1 mol of the feed material.

  On the other hand, in the gas phase exothermic reaction, the stability of the target product is not so great, so that the sequential reaction of the target product proceeds as the reaction proceeds, that is, the reaction conversion rate increases. Product selectivity tends to decrease. Here, the reaction conversion rate depends on the activity of the catalyst, and the conversion rate increases as the activity increases. In addition, the activity of the catalyst depends on the reaction temperature, and generally the activity increases as the reaction temperature rises. Therefore, if the reaction temperature rises for some reason, the reaction amount increases and successive reactions proceed. Therefore, the heat of reaction as a whole increases.

For example, when only the temperature rises by 5 ° C. without changing other conditions from the conditions of the previous paragraph, 82.5 mol of propane reacts (reaction rate 82.5%) out of 100 mol of supplied propane, and 50 .3 mol of acrylonitrile (yield 50.3%), 64.5 mol of CO ₂ (yield 21.5%), 32.1 mol of CO (yield 10.7%) The total reaction heat under these conditions is 637 × 0.503 + 2043 × 0.215 + 1194 × 0.107 = 887.4 (kJ / mol). The rate of change of the reaction heat as a whole can be expressed as a partial differential coefficient with respect to the temperature of the reaction heat as a whole. In this case, by linear approximation around this temperature, (887.4-846.5) ÷ 5 = 8.2 (kJ / mol · K). As can be seen from the calculation process, the partial differential coefficient related to the temperature of the reaction heat as a whole changes depending on the reaction temperature, the reaction rate of the raw materials, the contribution rate of each concurrent reaction (the yield of each product), etc. Dependent. If the overall rate of change in the heat of reaction is excessive, the control of the reaction temperature will become unstable due to heat balance, causing the temperature distribution in the reactor, and in extreme cases, it may cause thermal runaway of the reactor. From this point of view, it is preferable that the rate of change in reaction heat as a whole be as small as possible when selecting reaction conditions. Specifically, the reaction conditions should be selected so that the partial differential coefficient related to the temperature of the reaction heat as a whole is 40 kJ / mol (raw material) · K or less, preferably 30 kJ / mol (raw material) · K or less. .

  One or more temperature detectors are installed in the fluidized bed reactor used in the present invention. Multiple temperature detectors can be installed. If multiple detectors are installed, one of them may be selected and used, or two or more detectors may be selected and used after performing calculations such as averaging multiple temperature outputs. May be. As long as the temperature of the reactor can be stably measured, the installation position is not particularly limited, and it can be installed in a catalyst rich layer, a dilute layer, a gas outlet, or the like according to the purpose. The type of the temperature detector to be installed is not particularly limited, and a commonly used type of detector such as a thermocouple or a resistance temperature detector can be used.

  In the fluidized bed reactor used in the present invention, at least one heat removal pipe (hereinafter, referred to as a steady heat removal pipe) is used for the purpose of removing reaction heat to control the reaction temperature and recovering energy. And at least one temperature-adjusting heat removal pipe (hereinafter referred to as an adjustment heat removal pipe). The shape of the heat removal pipe to be installed is not particularly limited as long as it can be properly installed in the reactor. However, from the viewpoint of the availability of materials and the ease of processing, materials used for normal piping, that is, steel pipes and steel pipes. It is common to construct several U-shaped joints by combining joints. There are no particular restrictions on the material of the heat removal pipe, and pipe materials that are usually used, such as JIS G-, depending on the conditions used, that is, the temperature, pressure, presence or absence of corrosiveness of the fluid such as the cooling medium and reaction gas. It can be freely selected from general piping materials defined in 3454, G-3458, G-3459, etc., and commonly used steel pipe joints defined in JIS B-2311.

  A steady heat removal pipe is a heat removal pipe that is switched between use and non-use for the purpose of roughly adjusting the heat removal capacity according to the feed rate of the raw material or due to a decrease in the capacity of the heat removal pipe due to dirt, etc. Refers to what is used. Therefore, it is preferable to divide and install those having a certain margin with respect to the required heat removal amount into a plurality of series so that the total capacity can be roughly adjusted. Here, the series means a valve that has a valve capable of opening and closing the flow of the cooling medium in each unit, and that can be used / not used individually. The heat removal capacity of the heat removal pipe is determined by the area in contact with the dense part of the fluidized bed, the area in contact with the diluted layer of the fluidized bed, the temperature of the catalyst layer, the type of cooling medium to be communicated, the physical form, the supply temperature, and the supply speed. It is controlled by various factors. The total capacity of the steady heat removal pipe is not particularly limited as long as it is equal to or greater than the amount of heat to be removed (required capacity) determined from the amount of reaction heat generated, but preferably 130% or more of the necessary capacity, more preferably 150% or more. Most preferably, it has a capacity of 180% or more. Moreover, it is preferable to install 5 lines or more, more preferably 8 lines or more, and most preferably 10 lines or more. About these several series, the total of heat removal capability is roughly adjusted and used by switching use / nonuse suitably.

  The cooling medium leading to the steady heat removal pipe is not particularly limited as long as it can satisfy the necessary heat removal capability, but is preferably a liquid that can utilize heat removal by latent heat of vaporization by evaporating at the operating temperature of the reactor. More preferably, water is used, and water pressurized to 0.5 to 5 MPa (gauge pressure) is more preferably used. This is because the overall heat transfer coefficient of the heat removal tube can be made relatively high by using the latent heat of vaporization, so the amount of heat removal per unit surface area of the heat removal tube can be increased, and the required number of heat removal tubes can be reduced. Due to the ability to be reduced and the availability of the resulting coolant vapor. More preferably, the stationary heat removal tube is not only one that uses a liquid as a cooling medium but also one that uses a gas as a cooling medium, and more preferably a liquid is used as a cooling medium to evaporate a part of the cooling medium. In addition to the steady heat removal pipe recovered as a gas-liquid mixed phase flow of liquid-vapor, it is desirable to additionally provide a steady heat removal pipe that collects the generated steam as a cooling medium and collects it as superheated steam.

  The adjusted heat removal tube refers to a heat removal tube installed in the fluidized bed reactor that automatically adjusts the capacity according to the difference between the temperature detected by the temperature detection unit and the set temperature.

  As described above, the capacity of the heat removal pipe is determined by the area in contact with the dense layer portion of the fluidized bed, the area in contact with the diluted layer portion of the fluidized bed, the temperature of the catalyst layer, the type, physical form, and supply temperature of the cooling medium to be communicated. -Since it is governed by various factors such as the supply speed, one or more of the physical quantities that can be arbitrarily set, such as the supply temperature of the cooling medium, among the various governing factors when adjusting the capacity of the adjusted heat removal tube Or, the ability can be adjusted by changing the supply speed. Alternatively, a group of heat removal tubes may be prepared, and the heat transfer area may be changed by changing the number of tubes used to adjust the heat removal capacity as a result.

  There is no particular limitation on the cooling medium connected to the adjustment heat removal pipe as long as it can satisfy the necessary heat removal capacity and can adjust the heat removal pipe capacity, but preferably does not cause a phase change at the operating temperature of the reactor. Fluid, more preferably gas, more preferably gas pressurized to 0.2 to 5 MPa (gauge pressure), most preferably water vapor pressurized to 0.2 to 5 MPa (gauge pressure) may be used. . This is because by using a cooling medium that does not cause a phase change and using only sensible heat, the capacity of the adjustment heat removal tube changes almost in proportion to the change in the cooling medium supply speed, so that the capacity can be easily adjusted. is there.

  There is no particular limitation on the amount of heat removal between the amount of heat removed by the steady heat removal tube and the amount of heat removed by the adjustment heat removal tube, and it may be arbitrarily designed and set so that the catalyst layer temperature is stable. The amount of heat removal per unit surface area (capacity) of the heat removal tube can be increased by selecting the fluid that evaporates at the operating temperature of the reactor as the cooling medium used in the steady heat removal tube and using heat removal by latent heat of vaporization. Therefore, it is desirable to remove as much heat as possible with the steady heat removal tube within a range that does not adversely affect the temperature control of the reactor. It is preferable to design so that 80% or more, more preferably 85% or more, more preferably 90% or more of the amount of heat to be removed can be removed by a steady heat removal tube.

  The algorithm used to automatically adjust the capacity of the adjustment heat removal pipe according to the difference between the temperature detected by the temperature detector and the set temperature is to select the appropriate control variable to change the speed of the capacity adjustment. There is no particular limitation as long as it can be controlled within a predetermined range, and known arithmetic methods such as ON-OFF control, PID calculation control, fuzzy calculation control, neural network calculation control, etc. can be used. It is common to use a PID operation. For example, in the case of using PID calculation control, a predetermined capability adjustment change speed can be obtained by appropriately selecting a proportional band (P), an integration time (I), and a derivative time (D) according to the response characteristics of the system. Is obtained.

  In adjusting the capacity of the adjusted heat removal pipe, it is not necessary to use the entire adjustment range determined from the equipment specifications of the adjustment heat removal pipe, and the limited range can be used as a substantial adjustment range. There is no particular restriction on the method for limiting the adjustment range of the capacity.For example, when adjusting the capacity by changing the flow rate, the maximum flow rate can be adjusted by adjusting a valve provided in the flow path or inserting a restriction orifice. A method of limiting the adjustment range to a narrower range by limiting, a method of limiting the minimum flow rate by limiting the minimum flow rate by providing an appropriate bypass path to the adjustment valve, and automatic adjustment A method of limiting the movable range of the regulating valve and limiting the flow rate adjusting range to a narrower range can be adopted.

  The adjustment speed of the adjustment heat removal tube does not always need to be constant, and can always change depending on the result of calculation used for adjustment and the response characteristics of the system. However, it is important to keep the average adjustment speed within a predetermined range over almost the entire substantial adjustment range. Of the substantial adjustment range (0.0FS to 1.0FS), The average speed of change during the adjustment from 10% (0.1FS) of the capacity to 90% (0.9FS) of the capacity is defined as the capacity adjustment speed. The ability adjustment speed can be adjusted by the calculation method used for adjusting the ability, the value of the control variable used in the adopted calculation method, the operation speed of the control valve to be used, and the like. It is preferable that the capacity adjustment speed be 0.1 FS / min or more, more preferably 0.2 FS / min or more, and most preferably 0.25 FS / min or more. An appropriate control variable is set so that it is preferably 0.2 to 5.0 FS / min, and most preferably 0.25 to 4.0 FS / min. Although there is no upper limit for the capacity adjustment speed, there is a limit to the stability of the automatic adjustment calculation and the operation speed of the control valve. Therefore, up to about 6.0 FS / min is appropriate in the current technology.

  A preferred embodiment of the present invention will be described in more detail based on the drawings. FIG. 1 is an example of a fluidized bed reactor according to the present invention. A fluidized bed (2) is formed in the reactor (1) by a catalyst. A gas containing oxygen (usually air) is supplied from an oxygen introduction pipe (3) provided at the lower part of the reactor, and a gas containing a raw material is supplied from a raw material supply pipe (4). The gas containing the reaction product is extracted out of the reactor (1) through the extraction pipe (5).

  Inside the reactor (1), there are a steady heat removal pipe (6) that is located in the fluidized bed (2) and uses a liquid as a cooling medium, a steady heat removal pipe (7) that uses a gas as a cooling medium, and a regulated heat removal pipe. (8) is installed. In the figure, each of the heat removal tubes is shown as only one series, but usually a plurality of series is provided.

  A cooling medium is supplied to the stationary heat removal pipe (6) using the liquid from the gas-liquid separation container (9) by the pump (10). A part of the cooling medium evaporates by heat exchange between the fluidized bed (2) and the steady heat removal pipe (6), and returns to the gas-liquid separation container (9) as a gas-liquid two-phase flow to separate the gas and liquid. The amount of the liquid cooling medium reduced by evaporation is additionally supplied through the cooling medium additional pipe (11).

  A part of the cooling medium vapor generated in the steady heat removal pipe (6) is supplied to the steady heat removal pipe (7). Due to the heat exchange between the fluidized bed (2) and the steady heat removal pipe (7), the cooling medium vapor becomes superheated steam and is supplied outside the system through the superheated steam extraction pipe (12).

  The other part of the cooling medium vapor generated in the steady heat removal pipe (6) is supplied to the adjustment heat removal pipe (8). The supplied flow rate can be finely controlled by the flow rate control valve (13). Due to the heat exchange between the fluidized bed (2) and the adjusted heat removal pipe (8), the cooling medium vapor becomes superheated steam and is supplied outside the system through the superheated steam extraction pipe (14).

  Moreover, the temperature detection part (15) is installed in the fluidized bed (2). Although only one detection unit is shown in the figure, a plurality of detection units are usually installed by changing the position in the horizontal direction or the horizontal direction. The temperature information detected by the temperature detector (15) is transmitted to the temperature controller (16) and detected as the temperature of the fluidized bed. When a plurality of detection units are provided, an appropriate detection unit is selected and subjected to an appropriate calculation such as averaging, and then used as the temperature of the fluidized bed.

  The controller (16) performs a predetermined calculation based on the difference between the temperature of the fluidized bed thus detected and the set temperature, and operates the flow rate control valve (13) of the cooling medium based on the calculation result, The capacity of the adjusted heat removal pipe (8) is adjusted by adjusting the flow rate of the cooling medium leading to the adjusted heat removal pipe (8).

  Of the coolant vapor generated in the steady heat removal pipe (6), the surplus not used in the steady heat removal pipe (7) and the regulated heat removal pipe (8) is supplied outside the system through the saturated vapor extraction pipe (17). .

EXAMPLES Hereinafter, although this invention is demonstrated further in detail using an Example, this invention is not limited to a following example.
[Example 1]
A composite containing 12% fine powder of molybdenum, vanadium, antimony and niobium with an average particle size of 50 μm and a particle size of 44 μm or less in a fluidized bed reactor (1) of the type shown in FIG. 80 tons of oxide catalyst was charged. Oxygen supply tube (3) from the air 45000Nm ³ / Hr, the raw material supply pipe (4) by supplying propane 3000 Nm ³ / Hr and ammonia 2700 nm ³ / Hr were mixed gas from was mainly producing acrylonitrile.

  The fluidized bed (2) was manufactured using a steel pipe having an outer diameter of 114.3 mm specified in JIS G-3458 and a butt-welded 180 ° long elbow pipe having a corresponding diameter specified in JIS B-2311. A stationary heat removal pipe (6) 30 series (total length of straight pipe part is 1250 m) was installed. These steady heat removal tubes (6) are supplied with 800 ton / Hr of water at 235 ° C. from the gas-liquid separation vessel (9), and part of the water is evaporated, and the gas-liquid at a temperature of 236 ° C. and a pressure of 3 MPa (gauge pressure). Collected as a two-phase flow. The evaporation rate under steady conditions was 5.8%.

  Moreover, the steady heat removal pipe | tube (7) 8 series (the total total of a straight pipe part is 225m) manufactured using the same material as a steady heat removal pipe | tube (6) was installed. These steady heat removal pipes (7) include saturated water vapor at a temperature of 236 ° C. and a pressure of 3 MPa (gauge pressure) separated from the gas-liquid two-phase flow generated in the steady heat removal pipe (6) in the gas-liquid separation vessel (9). 17 tons / Hr was supplied and recovered as superheated steam at a temperature of 370 to 372 ° C.

  Furthermore, a 12-series adjustment heat removal pipe (8) manufactured using the same material as that of the steady heat removal pipe (6) (total length of the straight pipe portion is 370 m) was installed. These adjusted heat removal pipes (8) include saturated water vapor at a temperature of 236 ° C. and a pressure of 3 MPa (gauge pressure) separated in the gas-liquid separation vessel (9) from the gas-liquid two-phase flow generated in the steady heat removal pipe (6). Was supplied through a flow rate control valve (13) for adjusting the flow rate, and recovered as superheated steam at 370 to 438 ° C.

  A K-type thermocouple was installed as a temperature detector (15) at the center of the fluidized bed, and the thermoelectromotive force was converted into a temperature signal and detected by the temperature controller (16). In the temperature controller (16), based on the difference between the detected temperature of the reactor and the set temperature, PID calculation is performed using a DCS device CS3000 manufactured by Yokogawa Electronics Corporation, and a flow control valve ( The opening degree of 13) was adjusted, and the ability of the adjustment heat removal pipe (8) was adjusted.

  First, the set temperature given to the temperature controller (16) is set to 445 ° C., and the control variables (P: proportional band, I: integration time, D: differentiation) so that the capacity adjustment speed of the adjustment heat removal tube is 3.0 FS / min. Time) and automatic control operation was performed. At this time, the fluctuation range of the reactor temperature was 444.5 to 445.5 ° C., and automatic control was possible within a range of ± 0.5 ° C. with respect to the set temperature.

[Example 2]
In Example 1, the control variable was set such that the capacity adjustment speed of the adjusted heat removal tube was 0.2 FS / min without changing the set temperature, and automatic control operation was performed. At this time, the fluctuation range of the reactor temperature was 444 to 446 ° C., and control was possible within a range of ± 1 ° C. with respect to the set temperature.

[Comparative Example 1]
In Example 1, the control variable was set so that the capacity adjustment speed of the adjusted heat removal tube was 0.05 FS / min without changing the set temperature, and automatic control operation was performed. At this time, the reactor temperature showed a divergence tendency that continued to rise or fall, and automatic temperature control was not possible.

  According to the present invention, it is possible to finely control the temperature of a fluidized bed reactor widely used in industrial production of monomers useful for the production of various synthetic resins and synthetic fibers. Can be stably operated for a long period of time in a temperature range where the maximum yield is obtained.

An example of the fluidized bed reactor which can be used for this invention is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fluidized bed reactor 2 Catalyst fluidized bed 3 Oxygen introduction pipe 4 Raw material introduction pipe 5 Reaction product gas extraction pipe 6 Steady heat removal pipe 7 using a liquid cooling medium 7 Steady heat removal pipe 8 using a gas cooling medium 8 Adjustment heat removal pipe 9 Gas-liquid Separation vessel 10 Cooling medium transport pump 11 Cooling medium additional pipe 12 Superheated steam extraction pipe (for steady heat removal pipe)
13 Cooling medium flow rate control valve (Control heat removal pipe capacity control valve)
14 Superheated steam extraction pipe (for adjusting heat removal pipe)
15 Reactor temperature detector 16 Temperature controller 17 Saturated steam extraction pipe

Claims (9)

  1) At least one temperature detection unit, 2) at least one heat removal pipe to be used regularly, and 3) a fluidized bed reactor having at least one temperature adjustment heat removal pipe is used to carry out a gas phase exothermic reaction. In adjusting the heat removal capability of the heat removal pipe for temperature adjustment according to the difference between the temperature of the temperature detection unit and the set temperature, the temperature is controlled in a substantial adjustment range (0.0FS to 1.0FS). A method for controlling the temperature of a fluidized bed reactor, characterized in that the average rate of change during a change from a capacity of 10% (0.1 FS) to a capacity of 90% (0.9 FS) is 0.1 FS / min or more. .   In the temperature range in which the reaction is carried out, the total reaction heat including side reactions is 2500 kJ / mol (raw material) or less, and the partial differential coefficient related to the temperature of the total reaction heat is 40 kJ / mol (raw material) · K. The temperature control method for a fluidized bed reactor according to claim 1, wherein:   The temperature control method for a fluidized bed reactor according to claim 1 or 2, wherein the reaction to be carried out is a gas phase ammoxidation reaction using propane and / or propylene as a raw material, and the product of the reaction is acrylonitrile. .   The reaction to be carried out is a gas phase oxidation reaction using at least one selected from n-butane, 1-butene, 2-butene, butadiene, and benzene, and the product of the reaction is maleic anhydride The temperature control method of a fluidized bed reactor according to claim 1 or 2.   The fluidized bed according to claim 1 or 2, wherein the reaction to be carried out is a gas phase ammoxidation reaction using i-butene and / or i-butane as a raw material, and the product of the reaction is methacrylonitrile. Reactor temperature control method.   The fluidized bed reactor according to claim 1 or 2, wherein the reaction to be performed is a gas phase oxidation reaction using o-xylene and / or naphthalene as a raw material, and the product of the reaction is phthalic anhydride. Temperature control method.   The flow according to claim 1 or 2, wherein the reaction to be carried out is a gas phase oxidation reaction using phenol and methanol as raw materials, and the product of the reaction is 2,6-xylenol and / or o-cresol. Temperature control method for bed reactor.   The fluidized bed reactor according to claim 1 or 2, wherein the reaction to be performed is a gas phase ammoxidation reaction using methane and / or methanol as a raw material, and the product of the reaction is hydrocyanic acid (HCN). Temperature control method.   The fluidized bed according to claim 1 or 2, wherein the reaction to be performed is a gas phase ammoxidation reaction using at least one selected from ethane, ethene, and ethanol, and the product of the reaction is acetonitrile. Reactor temperature control method.

Images