阅读说明：本技术 一种变换冷凝液的综合处理工艺 (Comprehensive treatment process for conversion condensate ) 是由 李辉 张先茂 郭锐 王瑜 周庆国 李琴 李兴建 夏克勤 李青泽 沈康文 王利勇 于 2020-07-30 设计创作，主要内容包括：本发明公开了一种变换冷凝液的综合处理工艺,首先经常压汽提塔脱除变换冷凝液及气化高闪气中的NH<Sub>3</Sub>、H<Sub>2</Sub>S和CO<Sub>2</Sub>,顶部气相经过冷却后液相去加压汽提塔,采用单塔加压带侧线采出工艺,顶部气相经过冷凝分液后与常压汽提塔的气相混合经过水洗塔脱除气体中的氨后去硫回收；底部净化水冷却后外排或回用；中部侧线采出经过三级冷凝分液后再经过多效酸性尾气净化器脱除硫化氢后生产质量浓度为20%的无硫氨水。具有流程设计合理、装置运行稳定、产品附加值高的优点,环保效益巨大,解决了变换冷凝液处理后的氨水含硫及酸性气带氨的问题。(The invention discloses a comprehensive treatment process of conversion condensate, which comprises the steps of removing NH in the conversion condensate and gasified high-flash gas through a normal-pressure stripping tower 3 、H 2 S and CO 2 Cooling the top gas phase, then pressurizing the liquid phase in a stripping tower, adopting a single-tower pressurization side-line extraction process, mixing the top gas phase with the gas phase in the normal-pressure stripping tower after condensing and separating liquid, removing ammonia in the gas in a washing tower, and then desulfurizing and recycling; the purified water at the bottom is cooled and then discharged or recycled; and (3) extracting the sulfur-free ammonia water with the mass concentration of 20% from the middle lateral line, separating liquid by three-stage condensation, and removing hydrogen sulfide by a multi-effect acid tail gas purifier. The method has the advantages of reasonable flow design, stable device operation, high product added value and great environmental protection benefit, and solves the problem that the ammonia water treated by the conversion condensate contains sulfur and the acidic gas carries ammonia.)

1. The comprehensive treatment process for the conversion condensate is characterized by comprising the following steps of:

(1) firstly, the conversion condensate enters a normal pressure stripping tower after heat exchange, steam is introduced into the tower bottom, and NH in the condensate is removed₃、CO₂、H₂S, stripping and separating, and returning purified water at the bottom of the tower to the conversion device;

(2) the tower top acid gas treated in the step (1) enters a liquid separating tank of a normal pressure stripping tower after heat exchange and cooling, the separated gas phase is subjected to ammonia removal in the acid gas through a water washing tower, then passes through a liquid separating tank and a desulphurization recovery device, and the bottom liquid phase is cooled to a raw material water buffer tank;

(3) pressurizing the liquid phase obtained in the step (2) by a raw material water pump, and then feeding the liquid phase into a pressurized stripping tower in two ways: one path is cold feeding, the other path is heated by a primary condensation cooler and a raw material water-purified water heat exchanger to be used as hot feeding, steam is introduced into the bottom of a stripping tower, the bottom purified water is recycled or sent out of the device after heat exchange and temperature reduction, the top gas phase is subjected to condensation liquid separation and then sent to the water washing tower in the step (2) for ammonia washing and sulfur removal and recovery, and the middle side line extracted gas phase in the tower is subjected to tertiary condensation liquid separation;

(4) gas phase extracted from the lateral line of the pressurized stripping tower in the step (3) passes through a first-stage condensation cooler and then enters a first-stage dephlegmator, gas phase at the top of the first-stage dephlegmator passes through a second-stage condensation cooler and then enters a second-stage dephlegmator, gas phase at the top of the second-stage dephlegmator passes through a third-stage condensation cooler and then enters a third-stage dephlegmator, and liquid phase at the bottoms of the first-stage condensation cooler and the second-stage condensation cooler is cooled and then is;

(5) the gas phase at the top of the third-stage condensation cooler in the step (4) enters a multi-effect acid tail gas purifier from bottom to top to remove hydrogen sulfide in crude gas ammonia, and the hydrogen sulfide in the gas ammonia is further removed through a fine desulfurization reactor after liquid separation;

(6) and (3) mixing the gas ammonia treated in the step (5) with water from an ammonia water circulating pump, cooling to 40 ℃ through an ammonia water cooler, then feeding the mixture into an ammonia water absorption tank, and circularly absorbing the gas ammonia and the water to produce 20% ammonia water.

2. The process according to claim 1, characterized in that: in the step (1), the operation pressure of the normal-pressure stripping tower is 0.3-0.4 MPa, the temperature at the bottom of the tower is 135-145 ℃, and direct steam stripping is adopted.

3. The process according to claim 1, characterized in that: in the step (2), the operating pressure of the liquid separating tank of the normal-pressure stripping tower is 0.2-0.25 MPa, the operating temperature is 80-95 ℃, the operating temperature of the washing tower is 40-60 ℃, and the washing adopts a forced circulation washing mode.

4. The process according to claim 1, characterized in that: in the step (3), the operating pressure of the pressurized stripping tower is 0.5-0.6 MPa, the operating temperature at the bottom of the tower is 155-165 ℃, the operating temperature at the top of the tower is 110-130 ℃, the side-line extraction temperature is 150-155 ℃, direct steam stripping is adopted, and the stripping process is a single-tower pressurized side-line extraction mode.

5. The process according to claim 1, characterized in that: in the step (4), the operating pressure of the first-stage condensation cooler is 0.3-0.5 MPa, the operating temperature is 130-140 ℃, the operating pressure of the second-stage condensation cooler is 0.25-0.3 MPa, the operating temperature is 100-110 ℃, the operating pressure of the third-stage condensation cooler is 0.15-0.2 MPa, the operating temperature is 40-50 ℃, the gas phase extracted from the lateral line is subjected to high-temperature water diversion, and the hydrogen sulfide in the gas is separated in a low-temperature sulfur fixation mode, so that a large amount of gas ammonia can be extracted from the gas phase.

6. The process according to claim 1, characterized in that: and (5) dividing the multi-effect acid tail gas purifier into an upper alkali liquor absorption reactor and a lower alkali liquor absorption reactor, enabling the gas to pass through the multi-effect acid tail gas purifier from bottom to top, enabling the gas to be catalytically absorbed by the alkali liquor to produce sodium hydrosulfide, and enabling the catalytic absorption reaction to react with hydrogen sulfide to generate the sodium hydrosulfide under the action of a metal supported catalyst by using a prepared 30-40% NaOH solution as an absorbent.

7. The process according to claim 1, characterized in that: and (5) filling a fine desulfurizing agent in the fine desulfurizing reactor, wherein the fine desulfurizing agent is zinc oxide or a composite oxide fine desulfurizing agent and can remove hydrogen sulfide in the gas ammonia to less than 0.1 ppm.

8. The process according to claim 1, characterized in that: and (4) absorbing ammonia water in the step (6) to prepare ammonia water with the mass concentration of 20% in a circulating absorption mode, wherein an ammonia water absorption tank is used for standby, intermittent operation is adopted, switching is carried out after absorption saturation, and the ammonia gas volatilized from the ammonia water absorption tank is provided with a water-sealed tank.

9. The process according to claim 4, characterized in that: the pressurized stripping tower adopts a high-efficiency float valve and packing combined tray, the material is S32168, and the packing adopts rectangular saddle ring random packing.

10. The process according to claim 7, characterized in that: the alkali liquor absorption catalyst is of a composite metal net structure, the main components of composite metals are molybdenum, titanium, manganese and other alloy loaded active components, the operating temperature of the multi-effect acid tail gas purifier is 70-90 ℃, and the material is S30408.

Technical Field

The invention belongs to the field of coal chemical industry, and relates to a comprehensive treatment process for conversion condensate.

Background

In the process of gasifying coal water slurry and gasifying pulverized coal, gasified crude coal gas enters a carbon monoxide conversion section and reacts with water vapor under a catalyst and a certain temperature to generate carbon dioxide and hydrogen, and the carbon monoxide conversion section requires excessive steam, so that most of the water vapor is cooled to form conversion condensate except part of the water vapor participates in the reaction. The main impurities are ammonia, hydrogen sulfide, carbon dioxide and part of HCN, the impurities are usually removed by adopting a steam stripping method, and the purified condensate is sent back to an upstream gasification device for reuse.

The domestic technology adopts a single-tower steam stripping technology or a double-tower steam stripping technology, in the two technologies, the gas phase at the top of the tower is cooled and separated, the acid gas is desulfurized and recovered, and the liquid phase at the bottom is sent to a flue gas desulfurization system as ammonia water. These two processes have the following disadvantages:

the acid gas desulfurization recovery at the top contains partial ammonia which is not separated, and the acid gas desulfurization recovery is sent into a special ammonia burning nozzle and a specially designed combustion chamber which are needed for sulfur recovery, so that the processing capacity and the conversion capacity of sulfur recovery are reduced and new nitrogen oxide pollution is formed due to the high combustion temperature needed for ammonia burning; and the water content in the acid gas is high, the pipeline temperature is low, ammonium salt crystallization blockage is easy to generate, the overpressure of a stripping system is caused, and the main ammonium salts are as follows: crystallizing ammonium carbamate (2 NH) when meeting cold after carbon dioxide in acid gas reacts with ammonia gas₃(gas) + CO₂(gas) = = NH₂CO₂NH₄(white crystalline solid)), ammonia gas also reacts with hydrogen sulfide to form ammonium bisulfide, which is salt-formed and clogged at low temperatures, so that the phenomenon of clogging of crystals can occur only in the presence of a large amount of ammonia in the acid gas. Therefore, a part of enterprises adopt torch feeding for combustion and emptying, so that the environmental pollution is caused, most of acidic water in the torch liquid separating tank is discharged into a sewage treatment system, the impact of the acidic water with high ammonia nitrogen content on the sewage treatment system is large, and a part of enterprises adopt field emptying, so that the sulfur and ammonia pollution is brought to the surrounding environment and the noise pollution is caused.

Secondly, the liquid phase at the bottom of the separator is low-concentration sulfur-containing ammonia water which is designed to be sent to a flue gas desulfurization system, but the desulfurization system is seriously foamed due to the existence of hydrogen sulfide, ammonium sulfate is difficult to crystallize, and the color of the ammonium sulfate is yellow and green; therefore, a flue gas denitration system is introduced into part of enterprises and is used as a denitration agent of the denitration system, but the existence of hydrogen sulfide enables a catalyst to be ineffective, and elemental sulfur is easy to reduce, so that the system is blocked; part of enterprises return the sulfur-containing ammonia water to the coal slurry system for utilization, so that the ammonia smell is large, the operation environment is poor, and pipelines of the coal slurry system are often blocked by crystallization due to the existence of carbon dioxide; some enterprises introduce the ammonia into a gasification grey water system, so that the field ammonia smell is very large, the ammonia nitrogen in the system is enriched, and the quality of a final product is influenced.

Therefore, the traditional single-tower low-pressure stripping or double-tower stripping process can not recover ammonia and can not obtain acid gas suitable for a sulfur recovery device, and with the increasingly strict environmental protection requirements, new treatment methods and treatment processes are actively explored to achieve the aim of comprehensive utilization of resources, so that the process becomes an important and urgent task for the enterprises and scientific research institutions.

Disclosure of Invention

The invention aims to achieve the purpose of treating the conversion condensate through a reasonable process route, recover ammonia and sulfur in the condensate, ensure that the ammonia water is qualified sulfur-free ammonia water, has low ammonia content in acid gas, does not generate a blocking phenomenon, and can be sent to sulfur recovery for sulfur production, thereby solving the problems that the acid gas at the tower top blocks a pipeline with ammonia and the ammonia water has high sulfur content.

A comprehensive treatment process for conversion condensate comprises the following steps:

(1) firstly, the conversion condensate enters a normal pressure stripping tower after heat exchange, steam is introduced into the tower bottom, and NH in the condensate is removed₃、CO₂、H₂S, stripping and separating, and returning purified water at the bottom of the tower to the conversion device;

(2) the tower top acid gas treated in the step (1) enters a liquid separating tank of a normal pressure stripping tower after heat exchange and cooling, the separated gas phase is subjected to ammonia removal in the acid gas through a water washing tower, then passes through a liquid separating tank and a desulphurization recovery device, and the bottom liquid phase is cooled to a raw material water buffer tank;

(3) pressurizing the liquid phase obtained in the step (2) by a raw material water pump, and then feeding the liquid phase into a pressurized stripping tower in two ways: one path is cold feeding, the other path is heated by a primary condensation cooler and a raw material water-purified water heat exchanger to be used as hot feeding, steam is introduced into the bottom of a stripping tower, the bottom purified water is recycled or sent out of the device after heat exchange and temperature reduction, the top gas phase is subjected to condensation liquid separation and then sent to the water washing tower in the step (2) for ammonia washing and sulfur removal and recovery, and the gas phase is extracted from the middle side line of the tower to the step (4);

(4) gas phase extracted from the lateral line of the pressurized stripping tower in the step (3) passes through a first-stage condensation cooler and then enters a first-stage dephlegmator, gas phase at the top of the first-stage dephlegmator passes through a second-stage condensation cooler and then enters a second-stage dephlegmator, gas phase at the top of the second-stage dephlegmator passes through a third-stage condensation cooler and then enters a third-stage dephlegmator, and liquid phase at the bottoms of the first-stage condensation cooler and the second-stage condensation cooler is cooled and then is;

(5) the gas phase at the top of the third-stage condensation cooler in the step (4) enters a multi-effect acid tail gas purifier from bottom to top to remove hydrogen sulfide in crude gas ammonia, and the hydrogen sulfide in the gas ammonia is further removed through a fine desulfurization reactor after liquid separation;

(6) and (3) mixing the gas ammonia treated in the step (5) with water from an ammonia water circulating pump, cooling to 40 ℃ through an ammonia water cooler, then feeding the mixture into an ammonia water absorption tank, and circularly absorbing the gas ammonia and the water to produce 20% ammonia water.

The operation pressure of the normal-pressure stripping tower in the step (1) is 0.3-0.4 MPa, the temperature of the tower bottom is 135-145 ℃, and direct steam stripping is adopted.

In the step (2), the operating pressure of the liquid separating tank of the normal-pressure stripping tower is 0.2-0.25 MPa, the operating temperature is 80-95 ℃, the operating temperature of the washing tower is 40-60 ℃, and the washing adopts a forced circulation washing mode.

The cold-hot feeding ratio in the step (3) is 1: 2-1: 3, the operating pressure of the pressurized stripping tower is 0.5-0.6 MPa, the operating temperature at the bottom of the tower is 155-165 ℃, the operating temperature at the top of the tower is 110-130 ℃, the side-line extraction temperature is 150-155 ℃, direct steam stripping is adopted, and the stripping process is a single-tower pressurized side-line extraction mode; the pressurized stripping tower adopts a high-efficiency float valve and packing combined tray, the material is S32168, and the packing adopts rectangular saddle ring random packing.

In the step (4), the operation pressure of the first-stage condensation cooler is 0.3-0.5 MPa, the operation temperature is 130-140 ℃, the operation pressure of the second-stage condensation cooler is 0.25-0.3 MPa, the operation temperature is 100-110 ℃, the operation pressure of the third-stage condensation cooler is 0.15-0.2 MPa, the operation temperature is 40-50 ℃, the gas phase extracted from the side line is subjected to high-temperature water diversion, and the hydrogen sulfide in the gas is separated in a low-temperature sulfur fixation mode, so that a large amount of gas ammonia can be extracted from the gas phase.

The multi-effect acid tail gas purifier in the step (5) is divided into an upper alkali liquor absorption reactor and a lower alkali liquor absorption reactor, gas passes through the multi-effect acid tail gas purifier from bottom to top, the gas is catalytically absorbed by the alkali liquor to produce sodium hydrosulfide, and the catalytic absorption reaction is to take a prepared 30-40% NaOH solution as an absorbent to react with hydrogen sulfide under the action of a metal supported catalyst to generate the sodium hydrosulfide; the alkali liquor absorption catalyst is of a composite metal net structure, the main components of composite metals are molybdenum, titanium, manganese and other alloy loaded active components, the operating temperature of the multi-effect acid tail gas purifier is 70-90 ℃, and the material is S30408; the fine desulfurization reactor is filled with fine desulfurizing agent which is zinc oxide or composite oxide fine desulfurizing agent and can remove hydrogen sulfide in the gas ammonia to less than 0.1 ppm.

And (3) preparing ammonia water with the mass concentration of 20% by absorbing the ammonia water in the step (6) in a circulating absorption mode, using an ammonia water absorption tank for one use and one standby, performing intermittent operation, switching after saturated absorption, and configuring a water-sealed tank for the ammonia gas volatilized by the ammonia water absorption tank.

The invention has the advantages that:

(1) the gasified high-flash gas from the gasification device contains hydrogen sulfide, ammonia and carbon dioxide, the pressure is 0.5MPa, the temperature is about 158 ℃, the gas can meet the discharge requirement only by purification treatment, but the gas pressure is low, and a temperature heat source can be utilized, so that the normal-pressure stripping tower adopts a low-pressure stripping process, the gasified high-flash gas from the gasification device can be treated simultaneously when the conversion condensate is treated, and the gasified high-flash gas can also be used as the heat source of the tower, so that the steam consumption of the normal-pressure stripping tower is reduced.

(2) Aiming at the condition that carbon dioxide in the conversion condensate is larger than hydrogen sulfide and ammonia, if a single-tower pressurization side-stream extraction process is adopted, the load of the top of a stripping tower is large, and a large amount of carbon dioxide is contained in side-stream extraction gas, so that the ammonia gas desulfurization effect is influenced, and a side-stream acid gas pipeline is blocked. The process comprises the steps of firstly carrying out low-pressure steam stripping on the conversion condensate, separating the sulfur-containing ammonia water condensed after the temperature of the acid gas at the top of the tower is reduced to 90 ℃, then separately treating the sulfur-containing ammonia water, wherein the ammonia content of the ammonia water is far greater than that of hydrogen sulfide and carbon dioxide, and the process of single-tower pressurized belt line extraction is favorable for ammonia recovery; and a large amount of hydrogen sulfide and carbon dioxide are stripped by the normal pressure stripping tower and then are subjected to desulphurization recovery device along with the acid gas pipeline.

(3) Aiming at the problem that the acidic gas pipeline is blocked due to the ammonia carried by the acidic gas, a water washing tower is additionally arranged at an acidic gas outlet, and the ammonia in the acidic gas is washed by water to achieve the purpose of removing by utilizing the characteristics that the hydrogen sulfide and the carbon dioxide are insoluble in water and the ammonia is soluble in water. Because the reaction of ammonia and water is exothermic, the temperature of the washing tower is increased, and the reaction of ammonia washing is not facilitated due to high temperature, the washing tower adopts a circulating belt cooling washing process, purified water and water discharged from the washing tower both flow continuously, the concentration of ammonia in the water in the washing tower is not higher than 5%, the temperature is 40-60 ℃, the content of ammonia at an acid gas outlet is greatly reduced, and the problem of line blockage of an acid gas pipe is solved.

(4) The water replenishing of the water washing tower adopts the purified water at the bottom of the pressurized stripping tower, the purified water at the bottom of the No. 2 tower has very low ammonia and sulfur content and carbon dioxide content, meets the recycling requirement, and can save energy consumption after being recycled to the water washing tower.

(5) And performing alkali liquor absorption reaction on the crude ammonia gas subjected to three-stage condensation liquid separation, wherein a multi-effect acid tail gas purifier is divided into an upper alkali liquor absorption reactor and a lower alkali liquor absorption reactor, the gas passes through the multi-effect acid tail gas purifier from bottom to top, the gas is subjected to alkali liquor catalytic absorption to produce sodium hydrosulfide, and the catalytic absorption reaction is to react with 30-40% NaOH solution as an absorbent under the action of a metal supported catalyst to generate sodium hydrosulfide, so that the sodium hydrosulfide is removed and a sodium hydrosulfide product is also produced as a byproduct. The reaction principle is as follows:

H₂S+2NaOH=Na₂S+2H₂O

Na₂S+H₂S=2NaHS

(6) in order to ensure that the hydrogen sulfide in the gas ammonia is less than 0.1ppm, the gas ammonia is connected in series with a fine desulfurization reactor behind a multi-effect acid tail gas purifier, the fine desulfurization reactor is filled with a fine desulfurizing agent, the fine desulfurizing agent is a zinc oxide or composite oxide fine desulfurizing agent, the hydrogen sulfide in the gas ammonia can be removed to less than 0.1ppm, the ammonia water is ensured to be qualified, and the product reaches the standard.

(7) The ammonia water circulation absorption tank adopts two parallel operation, switches another when one of them ammonia water absorption tank reaches saturation, and qualified product ammonia water is stored more than 2 days, need not increase the ammonia water jar alone to the continuous circulation absorption of ammonia has been guaranteed.

Drawings

FIG. 1 is a schematic diagram of the integrated process for shift condensate treatment.

In the figure, 1 is an atmospheric stripping tower, 2 is a raw material water-atmospheric stripping tower top gas heat exchanger, 3 is an atmospheric stripping tower top cooler, 4 is an atmospheric stripping tower top liquid separation tank, 5 is a washing tower, 6 is a washing tower top liquid separation tank, 7 is a washing circulation cooler, 8 is a washing circulation pump, 9 is an atmospheric stripping tower top condensate cooler, 10 is a raw material water buffer tank, 11 is a raw material water pump, 12 is a cold feed cooler, 13 is a pressurized stripping tower, 14 is a primary condensation cooler, 15 is a raw material water-purified water heat exchanger, 16 is an acid gas cooler, 17 is a pressurized stripping tower top liquid separation tank, 18 is a purified water cooler, 19 is a primary dephlegmator, 20 is a secondary condensation cooler, 21 is a secondary dephlegmator, 22 is a tertiary condensation cooler, 23 is a tertiary dephlegmator, 24 is a multi-effect acid tail gas purifier, 25 is a liquid separation tank, 26 is a fine desulfurization reactor, 27 is an ammonia water mixer, 28 is an ammonia water cooler, 29 and 30 are ammonia water absorption tanks, 31 is an ammonia water circulating pump, 32 is an ammonia water pump, 33 is a second-grade condensate cooler, 34 is a reuse water tank, and 35 is a reuse water pump.

Detailed description of the preferred embodiment

The invention will be further illustrated with reference to fig. 1 and the examples, but the invention is not limited to the examples.