CN106809804A - A kind of natural gas reforming unit technique lime set recycling system and method - Google Patents

Abstract

The present invention provides a process condensate recycling system and method of a natural gas conversion device. The conversion reactor is connected to a conversion waste heat boiler, the other end of the conversion waste heat boiler is connected to a conversion gas heat recovery device, and one end of the conversion gas heat recovery device is connected to a condensate pump. The other end of the condensate pump is connected to the first inlet of the saturating tower top process condensate through the first pipeline, the saturating tower bottom process condensate outlet is connected to the reboiler heating inlet, and the reboiler process steam outlet is connected to the saturating tower bottom process The steam inlet, the reboiler process condensate outlet are connected to the condensate pump at the bottom of the tower, and the other end of the condensate pump at the bottom of the tower is connected to the second inlet of the process condensate at the top of the saturated tower; the saturated process gas outlet at the top of the saturated tower is connected to the conversion reactor . The process condensate recycling system and method of a natural gas conversion device described in the present invention can purify and recycle the process condensate while fully recovering effective gas, so as to truly realize the green cycle, energy saving and emission reduction of the whole device.

Description

A system and method for recovering and utilizing process condensate in a natural gas conversion unit

technical field

The invention belongs to the field of recovery and utilization of process condensate, and in particular relates to the recovery and utilization of natural gas conversion condensate.

Background technique

Natural gas conversion is an important component unit of natural gas to ammonia, natural gas to hydrogen and natural gas to methanol plants. The main reaction equation of natural gas conversion is as follows: CH ₄ +H ₂ O=3H ₂ +CO

Therefore, in addition to methane, water vapor is also a necessary reaction raw material in the natural gas conversion reaction. In order to improve the conversion rate of methane, in the traditional natural gas fertilizer process, the molar ratio of water vapor and methane in the conversion reactor is 3 : 1, far higher than the amount of water vapor required for the reaction, so a large amount of process condensate will be produced, and the conversion condensate cannot be effectively recovered and utilized, which often results in high energy consumption and high water consumption of the entire plant. Under the background that the country advocates energy conservation and emission reduction, it is of great significance to develop an economical, energy-saving and environmentally friendly conversion process condensate recovery process. The current method used is to use the stripping method to recover the process condensate, use steam to contact the process condensate and then transfer heat and mass, and the treated process condensate is recycled as boiler feed water. There are many processes in this process. The problem is that there is no guarantee that the process condensate after stripping can meet the water quality requirements for boiler feed water. If the natural gas contains heavy hydrocarbons and other components with a high boiling point, it will follow the process condensate into the boiler feed water system, causing pollution to the entire system.

Contents of the invention

In view of this, the present invention aims to propose a process condensate recycling system and method of a natural gas reforming unit, so as to purify and recycle the process condensate while fully recovering effective gas, so as to truly realize the green cycle and energy saving and reduction of the entire device. Row.

In order to achieve the above object, technical solution of the present invention is achieved in that way:

A process condensate recycling system of a natural gas reforming unit, comprising a reforming reactor, a reforming waste heat boiler, a condensate pump, a reboiler and a saturation tower;

The reforming reactor is connected to the cooling inlet of the reforming waste heat boiler, and the cooling outlet of the reforming waste heat boiler is connected to the reforming gas heat recovery device, one end of the reforming gas heat recovery device is connected to the downstream device of the reforming gas; the other end of the reforming gas heat recovery device is connected to the condensate pump, the other end of the condensate pump is connected to the first inlet of the process condensate at the top of the saturating tower through the first pipeline, the outlet of the process condensate at the bottom of the saturating tower is connected to the heating inlet of the reboiler, and the process steam outlet of the reboiler is connected to the saturating tower The bottom process steam inlet, the reboiler process condensate outlet are connected to the bottom condensate pump, and the other end of the tower bottom condensate pump is connected to the second inlet of the saturating tower top process condensate; the saturating tower top saturated process gas outlet is connected to A reforming reactor; the bottom of the saturation tower is provided with a preheated natural gas inlet.

The heating outlet of the conversion waste heat boiler is connected with the cooling inlet of the reboiler, and the cooling outlet of the reboiler is connected with the heating inlet of the conversion waste heat boiler through a second pipeline.

Further, a heat exchanger is arranged on the first pipeline; the heating inlet of the heat exchanger and the heating outlet of the heat exchanger are respectively connected to the condensate pump and the first inlet of the process condensate at the top of the saturation tower.

Further, the heat exchanger and the boiler feed water pump are arranged on the second pipeline; the cooling inlet of the heat exchanger and the cooling outlet of the heat exchanger are respectively connected to the cooling outlet of the reboiler and the boiler feed water pump, and the boiler feed water pump is another One end is connected to the heating inlet of the conversion waste heat boiler.

Further, the heating outlet of the conversion waste heat boiler is connected with the conversion reactor.

Further, a blowdown outlet is provided on the condensate side of the reboiler process.

The present invention also provides a method for recycling using the process condensate recovery and utilization system of a natural gas conversion plant, comprising the following steps:

(1) The reformed gas from the reforming reactor is cooled by the reforming waste heat boiler, and then the reformed gas passes through the reformed gas heat recovery device to form two streams, one stream enters the downstream device of the reformed gas as reformed gas, and the other stream is cooled as process condensate , pressurized by the condensate pump, and the pressurized process condensate enters the top of the saturation tower;

(2) The process condensate discharged from the process condensate outlet at the bottom of the saturated tower enters the reboiler for heating, and the process condensate becomes two parts, one part becomes process steam and enters the process steam inlet at the bottom of the saturated tower, and the other part is still The process condensate enters the second inlet of the process condensate at the top of the saturation tower through the condensate pump at the bottom of the tower;

(3) The preheated natural gas enters the saturation tower from the preheated natural gas inlet;

(4) The saturated process gas is discharged from the top of the tower and enters the conversion reactor.

Preferably, part of the by-product medium-pressure steam generated from the reforming waste heat boiler is discharged into the reforming reactor, and part of it enters the reboiler.

Preferably, the pressurized process condensate enters a heat exchanger for preheating.

Preferably, after being pressurized by the condensate pump, the pressure of the process condensate saturates the internal pressure of the tower.

Preferably, the temperature of the preheated natural gas entering the saturation tower from the preheated natural gas inlet is 250°C-380°C.

Compared with the prior art, a natural gas reforming plant process condensate recycling system and invention according to the present invention have the following advantages:

A reboiler is installed at the bottom of the saturation tower to provide a heat source for the saturation tower and avoid the pollution caused by the contact between process condensate and steam;

The heating outlet of the reforming waste heat boiler is connected to the reforming reactor inlet, and the steam required for the reaction can be supplemented according to the needs of different reforming processes;

The saturated process gas discharged from the top of the tower is directly sent to the conversion unit as the raw material of the conversion reaction, which can fully recover effective gases such as CO and _H2 in the process condensate, and increase the product yield.

Description of drawings

The drawings constituting a part of the present invention are used to provide a further understanding of the present invention, and the schematic embodiments and descriptions of the present invention are used to explain the present invention, and do not constitute an improper limitation of the present invention. In the attached picture:

Fig. 1 is a schematic diagram of a process condensate utilization system of a natural gas reforming device described in an embodiment of the present invention.

Explanation of reference signs:

1-reforming reactor; 2-reforming waste heat boiler; 3-condensate pump; 4-reboiler; 5-saturated tower; 6-heat exchanger; 7-boiler feed pump; 8-bottom condensate pump; 9 -first pipeline; 10-second pipeline; 11-reformed gas heat recovery device; 12-reformed gas downstream device; 13-preheated natural gas; 14-by-product medium-pressure steam; 21-cooling inlet of reformed waste heat boiler; 22-cooling outlet of conversion waste heat boiler; 23-heating inlet of conversion waste heat boiler; 24-heating outlet of conversion waste heat boiler; 41-heating inlet of reboiler; 42-reboiler process steam outlet; 43-reboiler process condensate outlet ;44-reboiler cooling inlet; 45-reboiler cooling outlet; 46-drainage outlet; 51-process condensate first inlet; 52-process condensate outlet; 53-process steam inlet; 54-process condensate first Two inlets; 55-saturated process gas outlet; 56-preheated natural gas inlet; 61-heat exchanger cooling inlet; 62-heat exchanger cooling outlet; 63-heat exchanger heating inlet; 64-heat exchanger heating outlet.

detailed description

It should be noted that, in the case of no conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

In describing the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", " The orientations or positional relationships indicated by "vertical", "horizontal", "top", "bottom", "inner" and "outer" are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and Simplified descriptions, rather than indicating or implying that the device or element referred to must have a particular orientation, be constructed and operate in a particular orientation, and thus should not be construed as limiting the invention. In addition, the terms "first", "second", etc. are used for descriptive purposes only, and should not be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, a feature defined as "first", "second", etc. may expressly or implicitly include one or more of that feature. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

In the description of the present invention, it should be noted that unless otherwise specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection. Connected, or integrally connected; it can be mechanically connected or electrically connected; it can be directly connected or indirectly connected through an intermediary, and it can be the internal communication of two components. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention based on specific situations.

The present invention will be described in detail below with reference to the accompanying drawings and examples.

As shown in Fig. 1, the present invention proposes a process condensate recovery and utilization system of a natural gas conversion plant, including a conversion reactor 1, a conversion waste heat boiler 2, a condensate pump 3, a reboiler 4 and a saturation tower 5;

The conversion reactor 1 is connected to the cooling inlet 21 of the conversion waste heat boiler, and the cooling outlet 22 of the conversion waste heat boiler is connected to the conversion gas heat recovery device 11, and one end of the conversion gas heat recovery device 11 is connected to the conversion gas downstream device 12, and the conversion gas heat recovery The other end of the device 11 is connected to the condensate pump 3, the other end of the condensate pump 3 is connected to the first inlet 51 of the process condensate at the top of the saturation tower 5 through the first pipeline 9, and the outlet 52 of the process condensate at the bottom of the saturation tower 5 is connected to Boiler heating inlet 41, reboiler process steam outlet 42 is connected to saturated tower 5 bottom process steam inlet 53, reboiler process condensate outlet 43 is connected to tower bottom condensate pump 8, and the other end of said tower bottom condensate pump 8 Connect the second inlet 54 of the process condensate at the top of the saturation tower 5; the saturated process gas outlet 55 at the top of the saturation tower 5 is connected to the conversion reactor 1; the bottom of the saturation tower 5 is provided with a preheated natural gas inlet 56;

The heating outlet 24 of the conversion waste heat boiler is connected to the cooling inlet 44 of the reboiler, the cooling outlet 45 of the reboiler is connected to the heating inlet 23 of the conversion waste heat boiler through the second pipeline 10, and the heating outlet 24 of the conversion waste heat boiler is connected to the conversion reactor 1 .

Example 1

The method for recovering using the above-mentioned a kind of natural gas reforming plant process condensate recovery and utilization system comprises the following steps:

(1) The 1100°C reformed gas from the reforming reactor 1 is cooled by the reforming waste heat boiler 2, and the temperature of the by-product medium-pressure steam can be heated to 280°C, and the cooled reformed gas is then cooled and exchanged by the reformed gas heat recovery device 11, Part of the reformed gas enters the downstream device 12 of the reformed gas, and the other part is cooled to 100°C to become a process condensate, in which the molar percentages of each component are 0.01% CO, 0.02% CO ₂ , 0.02% H ₂ , 0.04% CH ₄ , and the condensate The pump 3 pressurizes, and the process condensate after pressurizing to 30 barg enters the top of the saturation tower 5;

(2) The process condensate discharged from the process condensate outlet 52 at the bottom of the saturated tower 5 enters the reboiler 4 for heating, and the process condensed liquid is divided into two parts, and the process steam that a part becomes enters the process steam inlet at the bottom of the saturated tower 5 53, a part is still the process condensate, which is pressurized by the tower bottom condensate pump 8 to enter the second inlet 54 of the process condensate at the top of the saturation tower 5;

(3) 380°C preheated natural gas enters the saturation tower 5 from the preheated natural gas inlet 56, and the temperature of the saturated process gas drops to 270°C;

(4) The saturated process gas is discharged from the top of the tower at 270°C and enters the reforming reactor 1 .

Example 2

The method for recovering using the above-mentioned a kind of natural gas reforming plant process condensate recovery and utilization system comprises the following steps:

(1) The 850°C reformed gas from the reforming reactor 1 is cooled by the reforming waste heat boiler 2, and the temperature of the by-product medium-pressure steam rises to 226°C, and the cooled reformed gas is then cooled and exchanged by the reformed gas heat recovery device 11, Part of the reformed gas enters the downstream device 12 of the reformed gas, and the other part is cooled to 100°C to become a process condensate, in which the molar percentages of each component are 0.01% CO, 0.02% CO ₂ , 0.02% H ₂ , 0.04% CH ₄ , and the condensate The pump 3 pressurizes, and the process condensate after pressurizing to 26 barg enters the top of the saturation tower 5;

(2) The process condensate discharged from the process condensate outlet 52 at the bottom of the saturated tower 5 enters the reboiler 4 for heating, and the process condensed liquid is divided into two parts, and the process steam that a part becomes enters the process steam inlet at the bottom of the saturated tower 5 53, a part is still the process condensate, which is pressurized by the tower bottom condensate pump 8 to enter the second inlet 54 of the process condensate at the top of the saturation tower 5;

(3) 250°C preheated natural gas enters the saturation tower 5 from the preheated natural gas inlet 56, and the temperature of the saturated process gas drops to 220°C;

(4) The saturated process gas is discharged from the top of the tower at 220°C and enters the reforming reactor 1 .

Example 3

The method for recovering using the above-mentioned a kind of natural gas reforming plant process condensate recovery and utilization system comprises the following steps:

(1) The 1000°C reformed gas from the reforming reactor 1 is cooled by the reforming waste heat boiler 2, and the temperature of the by-product medium-pressure steam rises to 250°C, and the cooled reformed gas is then cooled and exchanged by the reformed gas heat recovery device 11, Part of the reformed gas enters the downstream device 12 of the reformed gas, and the other part is cooled to 100°C to become a process condensate, in which the molar percentages of each component are 0.01% CO, 0.02% CO ₂ , 0.02% H ₂ , 0.04% CH ₄ , and the condensate The pump 3 pressurizes, and the process condensate after pressurizing to 29 barg enters the top of the saturation tower 5;

(2) The process condensate discharged from the process condensate outlet 52 at the bottom of the saturated tower 5 enters the reboiler 4 for heating, and the process condensed liquid is divided into two parts, and the process steam that a part becomes enters the process steam inlet at the bottom of the saturated tower 5 53, a part is still the process condensate, which is pressurized by the tower bottom condensate pump 8 to enter the second inlet 54 of the process condensate at the top of the saturation tower 5;

(3) 320°C preheated natural gas enters the saturation tower 5 from the preheated natural gas inlet 56, and the temperature of the saturated process gas drops to 250°C;

(4) The saturated process gas is discharged from the top of the tower at 250°C and enters the conversion reactor 1 .

The process condensate recycling system and method of the natural gas reforming plant adopted in this embodiment fully recovers the effective gas while purifying and recycling the process condensate, and truly realizes the green cycle, energy saving and emission reduction of the whole device.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of the present invention. within the scope of protection.

Claims (10)

1. A natural gas conversion plant process condensate recycling system is characterized in that: it comprises a conversion reactor (1), a conversion waste heat boiler (2), a condensate pump (3), a reboiler (4) and a saturation tower ( 5); The conversion reactor (1) is connected to the cooling inlet (21) of the conversion waste heat boiler, and the cooling outlet (22) of the conversion waste heat boiler is connected to the conversion gas heat recovery device (11), and one end of the conversion gas heat recovery device (11) is connected to the conversion gas Downstream device (12), the other end of the converted gas heat recovery device (11) is connected to the condensate pump (3), and the other end of the condensate pump (3) is connected to the saturation tower (5) through the first pipeline (9) The first inlet (51) of the tower top process condensate, the process condensate outlet (52) at the bottom of the saturated tower (5) is connected to the reboiler heating inlet (41), and the reboiler process steam outlet (42) is connected to the saturated tower (5 ) process steam inlet (53) at the bottom of the tower, the reboiler process condensate outlet (43) is connected to the bottom condensate pump (8), and the other end of the bottom condensate pump (8) is connected to the top of the saturation tower (5) The second inlet of the process condensate (54); the saturated process gas outlet (55) at the top of the saturation tower (5) is connected to the conversion reactor (1); the bottom of the saturation tower (5) is provided with a preheated natural gas inlet (56); The heating outlet (24) of the conversion waste heat boiler is connected with the cooling inlet (44) of the reboiler, and the cooling outlet (45) of the reboiler is connected with the heating inlet (23) of the conversion waste heat boiler through the second pipeline (10). 2. A natural gas reforming plant process condensate recycling system according to claim 1, characterized in that: a heat exchanger (6) is arranged on the first pipeline (9); the heat exchanger heating inlet (63 ) and the heat exchanger heating outlet (64) are respectively connected with the condensate pump (3) and the first inlet (51) of the process condensate at the top of the saturation tower (5). 3. A natural gas conversion plant process condensate recycling system according to claim 1, characterized in that: the heat exchanger (6) and the boiler feed water pump (7) are arranged on the second pipeline (10) ); the heat exchanger cooling inlet (61) and the heat exchanger cooling outlet (62) are respectively connected to the reboiler cooling outlet (45) and the boiler feed water pump (7), and the other end of the boiler feed water pump (7) is connected to The conversion waste heat boiler heats the inlet (23). 4. A process condensate recycling system of a natural gas reforming plant according to claim 1, characterized in that: the heating outlet (24) of the reforming waste heat boiler is connected to the reforming reactor (1). The process condensate recycling system of a natural gas conversion unit according to claim 1, characterized in that: the process condensate side of the reboiler (4) is provided with a sewage discharge outlet (46). 6. A method for recovering using a natural gas conversion plant process condensate recovery and utilization system according to any one of claims 1-5, characterized in that: comprising the following steps: (1) The reformed gas from the reforming reactor (1) is cooled by the reforming waste heat boiler (2), and the reformed gas is then cooled by the reforming gas heat recovery device (11) into two streams, one of which is the reforming gas and enters the downstream device of the reforming gas (12); Another strand of cooling is process condensate, pressurized by condensate pump (3), and the process condensate after pressurization enters the saturation tower (5) tower top; (2) The process condensate discharged from the process condensate outlet (52) at the bottom of the saturated tower (5) enters the reboiler (4) for heating, and the process condensed liquid is divided into two parts, and a part becomes process steam and enters the saturated tower ( 5) The process steam inlet (53) at the bottom of the tower, a part of which is still the process condensate enters the second inlet (54) of the process condensate at the top of the saturated tower through the condensate pump (8) at the bottom of the tower; (3) preheated natural gas enters the saturation tower (5) from the preheated natural gas inlet (56); (4) The saturated process gas is discharged from the top of the tower into the conversion reactor (1). 7. The method for recovering using the natural gas conversion plant process condensate recovery and utilization system according to claim 6, characterized in that: a part of the by-product medium-pressure steam generated from the conversion waste heat boiler (2) is discharged into the conversion reactor ( 1), part of it enters the reboiler (4). 8. The method for recovering using the process condensate recycling system of the natural gas conversion plant according to claim 7, characterized in that: the pressurized process condensate enters the heat exchanger (6) for heating. 9. The method for recovering using the process condensate recycling system of the natural gas conversion plant according to claim 6, characterized in that: after pressurization by the condensate pump (3), the pressure of the process condensate is greater than that of the saturation tower (5) internal pressure. 10. The method for recovering using the natural gas conversion plant process condensate recycling system according to claim 6, characterized in that: the temperature of the preheated natural gas entering the saturation tower (5) from the preheated natural gas inlet (56) is 250 ℃-380℃.