WO2020164341A1

WO2020164341A1 - Process and system for thermal coupling of pressurized deacidification and ammonia distillation

Info

Publication number: WO2020164341A1
Application number: PCT/CN2020/070522
Authority: WO
Inventors: 李超; 李昊阳; 赵国峰
Original assignee: 中冶焦耐(大连)工程技术有限公司
Priority date: 2019-02-11
Filing date: 2020-01-06
Publication date: 2020-08-20
Also published as: CN109704366B; CN109704366A

Abstract

Provided is a process and system for the thermal coupling of pressurized deacidification and ammonia distillation. The system comprises a deacidification tower (1), an ammonia distillation tower (2), a pump (4), a condenser (5), a heat exchanger (3), a reboiler (6) and a valve (7); a top portion of the deacidification tower (1) is provided with an acid gas discharge outlet (11), an upper portion is provided with a mixed liquid inlet (12), a middle portion is provided with a lean liquid side line extraction port (13), a lower portion is provided with an ammonia gas inlet (14) and a gas-liquid phase return port (15), and a bottom portion is provided with an ammonia water outlet (16); a top portion of the ammonia distillation tower (2) is provided with an ammonia distillation gas outlet (21), an upper portion is provided with an ammonia water inlet (22) and a condensate inlet (23), a middle portion is provided with a lye inlet (24), and a bottom portion is provided with a gas-liquid phase inlet (25) and an ammonia distillation wastewater outlet (26). The described process ensures that the desorption pressure of a rich liquid may achieve stepwise desorption to complete the recovery of an ammonia product, while further increasing the pressure at the top of the ammonia distillation tower (2) such that the temperature at the top of the ammonia distillation tower (2) is higher than the temperature at the bottom of the deacidification tower (1); the heat of the condenser (5) at the top of the ammonia distillation tower is used to heat the bottom of the deacidification tower (1), and thermal coupling is carried out by means of a well-designed temperature system, thereby achieving the purpose of saving energy and reducing emissions.

Description

Process and system for heat coupling of pressure deacidification and ammonia distillation

Cross references to related applications

This application claims the priority of a Chinese patent application filed with the Chinese Patent Office on February 11, 2019, with the application number 201910109557.1, titled "A Process and System for Thermally Coupled Pressure Deacidification and Distillation of Ammonia", the entire content of which is approved The reference is incorporated in this application.

Technical field

The present disclosure relates to the technical field of coke oven gas purification, and in particular to a process and system for heat coupling of pressure deacidification and ammonia distillation.

Background technique

Ammonia desulfurization process is a common process used to remove hydrogen sulfide from raw gas. The process uses ammonia in coal gas as an alkali source, an ammonia-containing aqueous solution as a washing medium, and uses an ammonia-sulfur combined washing (absorption) process to remove hydrogen sulfide from the coal gas.

The method consists of a washing device and a deacidification and ammonia distillation device to form the main body of the absorption and desorption process, and the ammonia and hydrogen sulfide washing and stripping and desorption devices are closely integrated. In the absorption unit, the deacidification lean liquid with higher ammonia content and the stripping water are returned from the deacidification and ammonia distillation unit to absorb the ammonia and hydrogen sulfide in the raw gas to form a rich liquid containing ammonia and hydrogen sulfide to achieve the removal of raw gas The purpose of hydrogen sulfide. In the desorption unit, the deacidification lean liquid and stripping water (part of the ammonia distillation wastewater) obtained by the rich liquid desorbed by the deacidification ammonia distillation device are sent back to the washing device for recycling.

Compared with other desulfurization processes, the ammonia desulfurization process only uses water as the washing medium and the ammonia in the coal gas as the alkali source for absorption desulfurization, does not produce desulfurization waste liquid, and has the advantages of short overall gas purification process and low investment. However, in the existing process, the desorption unit (deacidification and distillation of ammonia) desorbs ammonia gas and hydrogen sulfide together, and the desorbed gas undergoes sulfur recovery after ammonia decomposition. In this process, ammonia, which can be used as the final chemical product, is directly decomposed as an impurity and cannot be effectively recovered. At the same time, the energy consumption and operating costs of the rich liquid desorption process are relatively high. Due to the large heat demand at the bottom of the tower, steam is usually directly passed into the bottom of the tower for heating, which also leads to the disadvantage of a large amount of waste water in the process.

At present, in order to effectively recover ammonia products and increase the ratio of lean liquid ammonia to sulfur, the process method of pressure deacidification and distillation of ammonia can be used to support the ammonia desulfurization process. By increasing the desorption pressure of the rich liquid, step-by-step desorption completes the recovery of ammonia products, while improving the quality of the lean liquid and increasing the desulfurization effect. However, this process still has the problems of high energy consumption and high operating cost.

Summary of the invention

The present disclosure provides a process and system for thermal coupling of pressure deacidification and ammonia distillation. While ensuring the desorption pressure of rich liquid can achieve stepwise desorption to complete the recovery of ammonia products, it further increases the pressure at the top of the ammonia distillation tower to make ammonia vaporize The temperature at the top of the tower is higher than the temperature at the bottom of the deacidification tower. The heat of the condenser at the top of the ammonia distillation tower is used to supply heat to the bottom of the deacidification tower, and the heat is coupled through a reasonable temperature system to achieve the purpose of energy saving and emission reduction.

The present disclosure provides a heat coupling process for pressure deacidification and ammonia distillation, which includes the following steps:

1) The rich liquid from the desulfurization tower is mixed with the remaining ammonia water, and then enters the top of the deacidification tower after heat exchange with the lean liquid of the deacidification tower; the top of the deacidification tower is pressurized to suppress the escape of ammonia, so as to deacidify The sour gas product at the top of the tower contains only a small amount of ammonia;

2) The acid gas escapes from the top of the deacidification tower, and the lean liquid extracted from the sideline of the deacidification tower exchanges heat with the rich liquid of the desulfurization tower and the remaining ammonia water, and then returns to the desulfurization tower for recycling;

3) The pressure at the top of the ammonia distillation tower is greater than the pressure at the bottom of the deacidification tower. After the liquid phase at the bottom of the deacidification tower is pressurized by the pump, part of it enters the top of the ammonia distillation tower for ammonia distillation, and the other part enters the condenser at the top of the ammonia distillation tower for heating , The heated gas and liquid phase return to the bottom of the deacidification tower;

4) After the ammonia vapor at the top of the ammonia distillation tower escapes, part of it enters the condenser at the top of the tower for condensation and concentration treatment, and the other part is adjusted by the valve and returned to the bottom of the deacidification tower as the heat source at the bottom of the deacidification tower;

5) After the ammonia vapor at the top of the ammonia distillation tower is concentrated by the condenser, the gas phase escapes to become ammonia products, and the liquid phase returns to the ammonia distillation tower as reflux;

6) Add alkaline solution to the middle of the ammonia distillation tower to remove fixed ammonia, the bottom of the ammonia distillation tower provides heat through a reboiler, and a part of the ammonia wastewater discharged from the bottom of the ammonia distillation tower is returned to the desulfurization section to be used as stripping water for ammonia scrubbing.

In one or more embodiments, the lye is an alkali metal hydroxide solution.

In one or more embodiments, the lye is sodium hydroxide solution.

In one or more embodiments, the concentration of the lye is 4-40%.

In one or more embodiments, at least a part of the ammonia distillation wastewater discharged from the bottom of the ammonia distillation tower is heat exchanged with the lye to preheat the lye.

In one or more embodiments, the process described herein further includes adjusting the amount of gas and liquid phase returned to the bottom of the deacidification tower after being heated by the condenser in step 3)/or the portion returned to the bottom of the deacidification tower in step 4) , So that sufficient heat is provided to the bottom of the deacidification tower.

A pressurized deacidification ammonia distillation heat coupling system, comprising a deacidification tower, an ammonia distillation tower, a pump, a condenser, a heat exchanger, a reboiler and a valve; the top of the deacidification tower is provided with an acid gas outlet , The upper part is provided with a mixed liquid inlet, the middle part is provided with a lean liquid side line extraction outlet, the lower part is provided with an ammonia vapor inlet and a gas-liquid return port, and the bottom is provided with an ammonia water outlet; where the mixed liquid inlet is connected to the first heat exchange medium outlet of the heat exchanger, The first heat exchange medium inlet of the heat exchanger is connected to the rich liquid conveying pipeline of the desulfurization tower and the remaining ammonia conveying pipe; the lean liquid side line outlet of the deacidification tower is connected to the second heat exchange medium inlet of the heat exchanger, and the second heat exchange medium inlet of the heat exchanger The heat exchange medium outlet is connected to the lean liquid transportation pipeline; the top of the ammonia distillation tower is provided with an ammonia vapor outlet, the upper part is provided with an ammonia water inlet and a condensate inlet, the middle is provided with an lye inlet, and the bottom is provided with a gas-liquid inlet and an ammonia wastewater outlet; The ammonia outlet of the deacidification tower is connected with the inlet of the pump, the outlet of the pump is respectively connected to the ammonia inlet of the ammonia distillation tower and the first heat exchange medium inlet of the condenser, and the first heat exchange medium outlet of the condenser is connected to the deacidification tower The gas and liquid phase return port of the ammonia distillation tower; the ammonia distillation gas outlet of the ammonia distillation tower is connected to the second heat exchange medium inlet of the condenser through a pipeline, and the ammonia distillation gas inlet of the deacidification tower is connected through another pipeline, and is connected to the ammonia vapor inlet A valve is provided on the connected pipeline; the second heat exchange medium outlet of the condenser is connected to the ammonia product pipeline, the condensate outlet of the condenser is connected to the condensate inlet of the ammonia distillation tower; the ammonia distillation wastewater outlet of the ammonia distillation tower and the ammonia wastewater pipeline Connected, the distilled ammonia wastewater pipeline is connected to the inlet of the reboiler through a branch pipeline, the outlet of the reboiler is connected with the gas-liquid phase inlet of the ammonia distilling tower, and the distilled ammonia wastewater pipeline downstream of the branch pipeline is additionally connected to the stripping water delivery pipeline.

In the deacidification tower, multiple layers of packing or trays are respectively arranged in the two-stage tower body located between the mixed liquid inlet and the lean liquid side line production outlet, and between the lean liquid side line production outlet and the ammonia distillation gas inlet.

In the ammonia distillation tower, multiple layers of packing or trays are respectively arranged in the two-stage tower body between the ammonia water inlet and the lye inlet, and between the lye inlet and the gas-liquid phase inlet.

In one or more embodiments, the system further includes a heat exchanger for distilling ammonia wastewater, configured to exchange at least a part of the ammonia wastewater discharged from the bottom of the ammonia distilling tower with the lye to preheat the Lye.

The present disclosure also provides a desulfurization system. The desulfurization system includes an absorption device and the thermally coupled system of the pressurized deacidification ammonia distillation described in the present disclosure.

In one or more embodiments, the absorption device is a desulfurization tower.

The present disclosure also provides the heat-coupled system of pressurized deacidification and distillation of ammonia according to the present disclosure or the use of the desulfurization system of the present disclosure to remove sulfur from gas.

In one or more embodiments, the gas is raw gas.

In one or more embodiments, the gas is raw coke oven gas.

Compared with the prior art, the beneficial effects of the present disclosure include at least:

1) By increasing the pressure at the top of the ammonia distillation tower, the temperature at the top of the ammonia distillation tower is higher than the bottom temperature of the deacidification tower. While the ammonia distillation tower condenser completes the concentration of ammonia, it also serves as the reboiler of the deacidification tower. Deacidification tower for heating;

2) Through the method of heat coupling, the steam consumption of the system is reduced, and at the same time, the required area of the reboiler at the bottom of the ammonia distillation tower is reduced; the indirect steam heating method is adopted to reduce the waste water discharge.

Description of the drawings

In order to explain the technical solutions of the embodiments of the present disclosure more clearly, the following will briefly introduce the drawings that need to be used in the embodiments. It should be understood that the following drawings only show certain embodiments of the present disclosure, and therefore do not It should be regarded as a limitation of the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative work.

Fig. 1 is a flow chart of the process of pressure deacidification and distillation of ammonia heat coupling according to the present disclosure.

Fig. 2 is a schematic flow chart of the heat coupling process of the pressurized deacidification ammonia distillation process of the present disclosure, in which the ammonia distilling waste water flowing from the bottom of the ammonia distillation tower is thermally coupled with the feed lye.

In the picture:

1. Deacidification tower

11. Sour gas outlet

12. Mixture inlet

13. Lean liquid sideline extraction outlet

14. Distilled ammonia gas inlet

15. Gas and liquid phase return port

16. Ammonia discharge outlet

2. Ammonia distillation tower

21. Distilled ammonia gas outlet

22. Ammonia inlet

23. Condensate inlet

24. Lye inlet

25. Gas and liquid inlet

26. Distilled ammonia wastewater outlet

27. Distilled ammonia wastewater valve

3. Heat exchanger

4. Pump

5. Condenser

6. Reboiler

7. Valve

8. Distilled ammonia wastewater heat exchanger.

detailed description

In order to make the objectives, technical solutions, and advantages of the embodiments of the present disclosure clearer, the technical solutions in the embodiments of the present disclosure will be described clearly and completely below. If the specific conditions are not specified in the implementation, it shall be carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used without the manufacturer's indication are all conventional products that can be purchased commercially.

Unless otherwise defined herein, scientific and technical terms used in connection with the present disclosure shall have the meanings commonly understood by those of ordinary skill in the art. Exemplary methods and materials are described below, but methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present disclosure.

The process and system of the present disclosure are typically suitable for ammonia desulfurization process. Ammonia desulfurization process is a process for removing hydrogen sulfide from raw gas. The process uses ammonia as the alkali source and ammonia-containing aqueous solution as the washing medium.

The specific embodiments of the present disclosure will be further described below in conjunction with the accompanying drawings:

As shown in Fig. 1, the process of pressure deacidification and distillation of ammonia heat coupling described in the present disclosure includes the following steps:

1) The rich liquid from the desulfurization tower is mixed with the remaining ammonia water, and enters the top of the deacidification tower 1 after heat exchange with the lean liquid of the deacidification tower through the heat exchanger 3; the top of the deacidification tower 1 is pressurized to suppress the escape of ammonia. The sour gas product at the top of the deacidification tower 1 contains only a small amount of ammonia;

2) The acid gas escapes from the top of the deacidification tower 1, and the lean liquid extracted from the side line of the deacidification tower 1 exchanges heat with the rich liquid of the desulfurization tower and the remaining ammonia water, and then returns to the desulfurization tower for recycling;

3) The pressure at the top of the ammonia distillation tower 2 is greater than the bottom pressure of the deacidification tower 1. After the liquid phase at the bottom of the deacidification tower 1 is pressurized by the pump 4, part of it enters the top of the ammonia distillation tower 2 for ammonia distillation, and the other part enters the ammonia distillation tower 2 The top condenser 5 is heated, and the heated gas and liquid phases are returned to the bottom of the deacidification tower 1;

4) After the ammonia vapor at the top of the ammonia distillation tower 2 escapes, a part of it enters the top condenser 5 for condensation and concentration treatment, and the other part is adjusted by the valve 7 to return to the bottom of the deacidification tower 1 as the bottom heat source of the deacidification tower 1;

5) After the ammonia vapor at the top of the ammonia distillation tower 2 is concentrated by the condenser 5, the gas phase escapes to become an ammonia product, and the liquid phase returns to the ammonia distillation tower 2 as a reflux;

6) Add lye to the middle of the ammonia distillation tower 2 to remove fixed ammonia, the bottom of the ammonia distillation tower 2 provides heat through the reboiler 6, and a part of the ammonia wastewater discharged from the bottom of the ammonia distillation tower 2 is returned to the desulfurization section for the desulfurization and ammonia washing Stripped water.

At the heat exchanger 3, the mixture of the rich liquid from the desulfurization tower and the remaining ammonia water exchanges heat with the lean liquid of the deacidification tower from the lean liquid side line extraction outlet 13 in the middle of the deacidification tower, which makes full use of the The waste heat reduces the heat required in the deacidification tower 1 and realizes the reuse of heat.

In one or more embodiments, at least a part of the ammonia distilling wastewater discharged from the bottom of the ammonia distilling tower performs heat exchange with the lye to preheat the lye. In this way, the heat of the ammonia distillation wastewater discharged from the bottom of the ammonia distillation tower is further recovered and utilized, and the heat required for the operation of the ammonia distillation tower and the entire system is reduced.

A part of the ammonia distilling wastewater discharged from the bottom of the ammonia distilling tower 2 is returned to the desulfurization section to be used as stripping water for desulfurization and ammonia washing. In the above step (1), after the rich liquid is mixed with the remaining ammonia water, it enters the top of the deacidification tower 1 after heat exchange with the lean liquid of the deacidification tower through the heat exchanger 3; Therefore, the sour gas product at the top of the deacidification tower 1 contains only a small amount of ammonia. In one or more embodiments, the operating pressure at the top of the deacidification tower is 300-700 KPaG. In one or more embodiments, the temperature at the top of the deacidification tower is 95-140°C.

In one or more embodiments, the remaining ammonia water is wastewater generated during the coal coking process. In one or more embodiments, the remaining ammonia water includes free ammonia (ie, NH ₃ molecules) and/or fixed ammonia (ie, ammonium salt in which NH ₄ ⁺ ions are present). In one or more embodiments, the remaining ammonia water includes 1 to 4 g/l of free ammonia (ie, NH ₃ molecules) and/or 1 to 3 g/l of fixed ammonia (ie, ammonium salt in which NH ₄ ⁺ ions exist). In one or more embodiments, in addition to free ammonia and fixed ammonia, the remaining ammonia water also includes 0.5-2 g/l hydrogen sulfide and/or 0.5-2 g/l carbon dioxide.

In one or more embodiments, the rich liquid from the desulfurization tower contains 9-18g/l ammonia (NH ₃ and NH ₄ ⁺ ), 1.5-5.5g/l hydrogen sulfide, 1.5-5g/l Aqueous solution of carbon dioxide, 0.5-3g/l hydrogen cyanide and a small amount of organic aromatic hydrocarbons.

In the above step (2), acid gas escapes from the top of the deacidification tower 1. In one or more embodiments, the acid gas escaping from the top of the deacidification tower 1 is mainly composed of hydrogen sulfide H ₂ S. For example, acid gases include hydrogen sulfide, carbon dioxide, and water vapor. In one or more embodiments, the hydrogen sulfide content in the acid gas is 20%-70% by weight, such as 30-60%, such as 40-50%. In one or more embodiments, the carbon dioxide content is 10%-50% by weight, such as 20-40%, such as 30-35%.

After heat exchange between the lean liquid extracted from the side line of the deacidification tower 1, the rich liquid of the desulfurization tower and the remaining ammonia water, the rich liquid of the desulfurization tower and the remaining ammonia water are preheated to 100-160°C. The lean liquid after heat exchange is further cooled and then returned to the desulfurization tower for recycling. In one or more embodiments, the proportion of the lean liquid returning to the desulfurization section is set according to the requirements of the preceding desulfurization section.

In step (3), the pressure at the top of the ammonia distillation tower 2 is greater than the pressure at the bottom of the deacidification tower 1. The pressure at the top of the ammonia distillation tower is 350-800kpag, and the temperature at the top of the tower is 140-180°C. After the liquid phase at the bottom of the deacidification tower 1 is pressurized by the pump 4, part of it enters the top of the ammonia distillation tower 2 for ammonia distillation, and the other part enters the condenser 5 at the top of the ammonia distillation tower 2 for heating. The bottom of acid tower 1. In one or more embodiments, the ratio of the part returning to the deacidification tower to the part entering the ammonia distillation tower is 0.1-6.

In step (4), a part of the off gas from the top of the ammonia distillation tower 2 enters the top condenser 5 for condensation and concentration treatment. Another part of the gas at the top of the ammonia distillation tower 2 is adjusted by the valve 7 and returned to the bottom of the deacidification tower 1 as the heat source at the bottom of the deacidification tower 1. In one or more embodiments, the portion of the gas at the top of the ammonia distillation tower 2 returned to the bottom of the deacidification tower 1 accounts for 0% to 60% of the total gas discharged from the top of the tower.

One or both of the liquid phase returned to the bottom of the deacidification tower 1 after heating in step (3) and the part of the gas at the top of the ammonia distillation tower returned to the bottom of the deacidification tower 1 in step (4) can be used for the deacidification tower Heating at the bottom. In one or more embodiments, when the liquid phase returned to the bottom of the deacidification tower 1 after heating in step (3) is not enough to provide sufficient heat for the deacidification tower, the valve 7 can be adjusted to increase the return to the deacidification tower. 1 The bottom part of the ammonia distillation tower top gas to provide sufficient heat.

In step (5), after the ammonia vapor at the top of the ammonia distillation tower 2 is concentrated by the condenser 5, the gas phase escapes to become an ammonia product, and the liquid phase is returned to the ammonia distillation tower 2 as a reflux. In one embodiment, the reflux ratio of the liquid phase returning to the ammonia distillation tower 2 is 1-4, or it can be adjusted according to the pressure. In one or more embodiments, the ammonia product obtained after concentration mainly contains ammonia and water vapor and a small amount of acidic impurities such as hydrogen cyanide and hydrogen sulfide. For example, in the ammonia product obtained after concentration, the ammonia content is 10%-24% by weight, the water vapor content is 75%-88% by weight, and/or the remaining acid gas is about 2%.

In step (6), lye is added to the middle of the ammonia distillation tower 2 to remove fixed ammonia, the bottom of the ammonia distillation tower 2 provides heat through the reboiler 6, and a part of the ammonia wastewater discharged from the bottom of the ammonia distillation tower 2 is returned to the desulfurization section. Used as stripping water for ammonia scrubbing. In one or more embodiments, the lye is an alkali metal hydroxide solution. In one or more embodiments, the lye is sodium hydroxide solution. In one or more embodiments, the concentration of the lye is 4-40%, such as 10-35%, such as 12-30%, such as 15-25%. In one or more embodiments, the volume ratio of the liquid phase at the bottom of the ammonia distillation tower into the reboiler and the part discharged as the ammonia wastewater is 0.5-2, such as 0.7-1.5, such as 0.9-1.2. In one or more embodiments, the volume percentage of the liquid phase effluent from the bottom of the ammonia distillation tower into the reboiler accounts for 30-60%, such as 40-50%, such as 42-58. %.

In the deacidification tower 1, the rich liquid of the desulfurization tower flows from top to bottom, and the bottom liquid is heated to produce an upward gas phase. The gas phase flows countercurrently with the liquid (rich liquid of the desulfurization tower) from bottom to top, and the mass and heat transfer between the gas and the liquid in the deacidification tower 1 is sufficient. As a result, the hydrogen sulfide content in the bottom-up gas phase continues to increase. On the contrary, the hydrogen sulfide content in the liquid flowing from top to bottom continues to decrease. For example, the deacidification tower 1 may be a packed tower. The packed tower uses packing as the basic component of gas and liquid contact and mass transfer. The liquid flows from top to bottom in a film form on the surface of the packing, and the gas phase flows in the reverse direction from the bottom to the top of the continuous phase and flows between the gas and liquid. Mass transfer and heat transfer. The component concentration and temperature of the two phases change continuously along the tower height.

In the ammonia distillation tower 2, the rich liquid after deacidification flows from top to bottom, and the bottom liquid is heated to generate an upward gas phase. The gas phase flows countercurrently with the liquid from bottom to top. The remaining small part of acidic substances and ammonia molecules that are not completely removed in the deacidification tower escape from the liquid phase into the gas phase and finally escape from the top of the tower. The side wall of the ammonia distillation tower 2 is added with lye, which reacts with the NH ₄ ⁺ in the liquid phase to generate free ammonia (NH ₃ molecules), which escapes from the liquid phase to the gas phase, and finally escapes from the top of the tower. Adding lye from the side wall can avoid the problem of adding lye directly from the top to cause residual acidic substances to react with the alkali to form salts into the wastewater.

A pressurized deacidification ammonia distillation heat coupling system, including deacidification tower 1, ammonia distillation tower 2, pump 4, condenser 5, heat exchanger 3, reboiler 6 and valve 7; said deacidification tower 1 The top is equipped with an acid gas discharge outlet 11, the upper part is equipped with a mixed liquid inlet 12, the middle part is equipped with a lean liquid side line extraction outlet 13, the lower part is equipped with a distilled ammonia gas inlet 14 and a gas-liquid return port 15, and the bottom is equipped with an ammonia discharge outlet 16; The liquid inlet 12 is connected to the first heat exchange medium outlet of the heat exchanger 3, and the first heat exchange medium inlet of the heat exchanger 3 is connected to the desulfurization tower rich liquid conveying pipe and the remaining ammonia conveying pipe; the lean liquid side outlet 13 of the deacidification tower 1 Connected to the second heat exchange medium inlet of the heat exchanger 3, and the second heat exchange medium outlet of the heat exchanger 3 is connected to the lean liquid conveying pipe; the top of the ammonia distillation tower 2 is provided with an ammonia vapor outlet 21, and the upper part is provided with an ammonia water inlet 22 and the condensate inlet 23, the lye inlet 24 is arranged in the middle, the gas-liquid inlet 25 and the ammonia wastewater outlet 26 are arranged at the bottom; the ammonia water discharge outlet 16 of the deacidification tower 1 is connected to the inlet of the pump 4, and the outlet of the pump 4 The ammonia water inlet 22 of the ammonia distillation tower 2 and the first heat exchange medium inlet of the condenser 5 are respectively connected, and the first heat exchange medium outlet of the condenser 5 is connected to the gas-liquid phase return port 15 of the deacidification tower 1; The ammonia vapor outlet 21 is connected to the second heat exchange medium inlet of the condenser 5 through a pipeline, the ammonia vapor inlet 14 of the deacidification tower 1 is connected through another pipeline, and a valve is provided on the pipeline connected to the ammonia vapor inlet 14 7; The second heat exchange medium outlet of the condenser 5 is connected to the ammonia product pipeline, the condensate outlet of the condenser 5 is connected to the condensate inlet 23 of the ammonia distillation tower 2; the ammonia distillation wastewater outlet 26 of the ammonia distillation tower 2 and the ammonia wastewater Pipe connection, the ammonia distillation wastewater pipeline is connected to the inlet of the reboiler 6 through the branch pipeline, the outlet of the reboiler 6 is connected to the vapor-liquid phase inlet 25 of the ammonia distillation tower 2, and the ammonia distillation wastewater pipeline downstream of the branch pipeline is additionally connected to the steam stripper Water pipeline.

In one or more embodiments, the deacidification tower 1 is selected from a packed tower or a plate tower. In the deacidification tower 1, multiple layers of packing or trays are respectively arranged in the two-stage tower body located between the mixed liquid inlet 12 and the lean liquid side line production outlet 13 and between the lean liquid side line production outlet 13 and the distilled ammonia gas inlet 14.

In one or more embodiments, the ammonia distillation tower 2 is selected from a packed tower or a plate tower. The ammonia distillation tower 2 is provided with multiple layers of packing or trays in the two-stage tower body located between the ammonia water inlet 22 and the lye inlet 24, and between the lye inlet 24 and the gas-liquid phase inlet 25.

As the pressure at the top of the ammonia distillation tower is increased, the temperature at the top of the ammonia distillation tower is higher than the temperature at the bottom of the deacidification tower. Therefore, the condenser 5 of the ammonia distillation tower is used for concentrating ammonia as well as deacidification The reboiler of the tower supplies heat to the deacidification tower.

In one or more embodiments, the system further includes a distilled ammonia wastewater heat exchanger 8 configured to exchange at least a part of the distilled ammonia wastewater discharged from the bottom of the ammonia distillation tower with the lye to preheat the heat exchanger. Said lye, as shown in Figure 2.

In one or more embodiments, an ammonia distillation wastewater valve 27 is provided between the bottom of the ammonia distillation tower and the discharge end of the ammonia distillation wastewater.

The present disclosure provides a desulfurization system, the desulfurization system includes an absorption device and the heat-coupled system of pressurized deacidification and ammonia distillation described herein.

In one or more embodiments, the absorption device is a desulfurization tower.

The present disclosure provides the heat-coupled system of pressurized deacidification and distillation of ammonia described herein or the use of the desulfurization system described herein to remove sulfur from gas.

In one or more embodiments, the gas is raw gas.

In one or more embodiments, the gas is raw coke oven gas.

The heat-coupled system of pressurized deacidification and ammonia distillation of the present disclosure not only reuses heat energy in the system, but also realizes the heat coupling between the heat-coupled system of pressurized deacidification and ammonia distillation and the desulfurization absorption device, thus saving overall Heat energy is reduced, operating costs are reduced, and energy saving and emission reduction are realized.

The above are only preferred specific implementations of the present disclosure, but the protection scope of the present disclosure is not limited to this. Anyone familiar with the technical field within the technical scope disclosed in the present disclosure, according to the technical solutions of the present disclosure Equivalent replacements or changes to the disclosed concepts should be covered by the protection scope of the present disclosure.

Industrial applicability

The present disclosure reduces the steam consumption of the system by means of heat coupling, and at the same time reduces the required area of the reboiler at the bottom of the ammonia distillation tower; adopts the method of indirect steam heating to reduce the waste water discharge; and realizes the deacidification and ammonia distillation section of the desulfurization process Coupled with the heat of the absorption section, energy saving and emission reduction.

Claims

A pressurized deacidification ammonia distillation heat coupling process is characterized in that it comprises the following steps:

1) The rich liquid from the desulfurization tower is mixed with the remaining ammonia water, and then enters the top of the deacidification tower after heat exchange with the lean liquid of the deacidification tower; the top of the deacidification tower is pressurized to suppress the escape of ammonia, so as to deacidify The sour gas product at the top of the tower contains only a small amount of ammonia;

2) The acid gas escapes from the top of the deacidification tower, and the lean liquid extracted from the sideline of the deacidification tower exchanges heat with the rich liquid of the desulfurization tower and the remaining ammonia water, and then returns to the desulfurization tower for recycling;

3) The pressure at the top of the ammonia distillation tower is greater than the pressure at the bottom of the deacidification tower. After the liquid phase at the bottom of the deacidification tower is pressurized by the pump, part of it enters the top of the ammonia distillation tower for ammonia distillation, and the other part enters the condenser at the top of the ammonia distillation tower for heating , The heated gas and liquid phase return to the bottom of the deacidification tower;

4) After the ammonia vapor at the top of the ammonia distillation tower escapes, part of it enters the condenser at the top of the tower for condensation and concentration treatment, and the other part is adjusted by the valve and returned to the bottom of the deacidification tower as the heat source at the bottom of the deacidification tower;

5) After the ammonia vapor at the top of the ammonia distillation tower is concentrated by the condenser, the gas phase escapes to become ammonia products, and the liquid phase returns to the ammonia distillation tower as reflux;

6) Add alkaline solution to the middle of the ammonia distillation tower to remove fixed ammonia, the bottom of the ammonia distillation tower provides heat through a reboiler, and a part of the ammonia wastewater discharged from the bottom of the ammonia distillation tower is returned to the desulfurization section to be used as stripping water for ammonia scrubbing.
The heat-coupled process for pressurized deacidification and distillation of ammonia according to claim 1, wherein the lye is an alkali metal hydroxide solution.
The heat-coupled process for pressurized deacidification and distillation of ammonia according to claim 1 or 2, wherein the lye is a sodium hydroxide solution.
The pressurized deacidification ammonia distillation heat coupling process according to any one of claims 1-3, wherein the concentration of the lye is 4-40%.
The pressurized deacidification ammonia distilling heat coupling process according to any one of claims 1 to 4, wherein at least a part of the ammonia distilling wastewater discharged from the bottom of the ammonia distilling tower undergoes heat exchange with the lye to pre- Heat the lye.
The pressurized deacidification and distillation of ammonia heat coupling process according to any one of claims 1-5, characterized in that it further comprises adjusting the gas and liquid phase return to the bottom of the deacidification tower after being heated by a condenser in step 3) The amount/or the part returned to the bottom of the deacidification tower in step 4) so as to provide sufficient heat to the bottom of the deacidification tower.
A pressured deacidification ammonia distillation heat coupling system, characterized in that it comprises a deacidification tower, an ammonia distillation tower, a pump, a condenser, a heat exchanger, a reboiler and a valve; the top of the deacidification tower is provided with The sour gas discharge outlet, the upper part is equipped with a mixed liquid inlet, the middle part is equipped with a lean liquid side-line extraction outlet, the lower part is equipped with a vaporized ammonia gas inlet and a gas-liquid return port, and the bottom is equipped with an ammonia water outlet; where the mixed liquid inlet is connected to the first heat exchanger Heat medium outlet, the first heat exchange medium inlet of the heat exchanger is connected to the rich liquid conveying pipeline of the desulfurization tower and the remaining ammonia conveying pipe; the lean liquid side line outlet of the deacidification tower is connected to the second heat exchange medium inlet of the heat exchanger for heat exchange The second heat exchange medium outlet of the reactor is connected to the lean liquid transportation pipeline; the top of the ammonia distillation tower is provided with an ammonia vapor outlet, the upper part is provided with an ammonia water inlet and a condensate inlet, the middle is provided with an lye inlet, and the bottom is provided with a gas-liquid inlet and steam Ammonia wastewater outlet; the ammonia discharge outlet of the deacidification tower is connected to the inlet of the pump, and the outlet of the pump is respectively connected to the ammonia inlet of the ammonia distillation tower and the first heat exchange medium inlet of the condenser, and the first heat exchange medium outlet of the condenser Connect the gas and liquid phase return ports of the deacidification tower; the ammonia vapor outlet of the ammonia distillation tower is connected to the second heat exchange medium inlet of the condenser through a pipeline, and the ammonia vapor inlet of the deacidification tower is connected through another pipeline, and is connected with A valve is provided on the pipeline connected to the ammonia vapor inlet; the second heat exchange medium outlet of the condenser is connected to the ammonia product pipeline; the condensate outlet of the condenser is connected to the condensate inlet of the ammonia vaporizer; The distilled ammonia wastewater pipeline is connected, the distilled ammonia wastewater pipeline is connected to the inlet of the reboiler through the branch pipeline, the outlet of the reboiler is connected to the gas-liquid phase inlet of the ammonia distillation tower, and the distilled ammonia wastewater pipeline downstream of the branch pipeline is additionally connected with stripping water Conveying pipeline.
The pressurized deacidification ammonia distilling heat coupling system according to claim 7, wherein the deacidification tower is located between the mixed liquid inlet and the lean liquid side line extraction outlet, and the lean liquid side line extraction outlet and the distilled ammonia gas The two-stage tower body between the inlets is respectively provided with multiple layers of packing or trays.
The thermally coupled system for pressurized deacidification and distillation of ammonia according to claim 7 or 8, wherein the ammonia distillation tower is located between the ammonia inlet and the lye inlet, and between the lye inlet and the gas-liquid phase inlet. Multi-layer packing or trays are respectively arranged in the two-stage tower.
The pressurized deacidification ammonia distilling heat-coupled system according to any one of claims 7-9, wherein the system further comprises a distilled ammonia waste water heat exchanger configured to make the distilled ammonia discharged from the bottom of the ammonia distilling tower At least a part of the ammonia waste water exchanges heat with the lye to preheat the lye.
A desulfurization system, the desulfurization system comprising an absorption device and the pressure-deacidified ammonia distilled heat-coupled system according to any one of claims 7-9.
The desulfurization system according to claim 11, wherein the absorption device is a desulfurization tower.
The use of the pressurized deacidification ammonia distillation thermally coupled system according to any one of claims 6-10 or the use of the desulfurization system according to claim 11 or 12 for removing sulfur from a gas.
The use according to claim 13, wherein the gas is raw gas.
The use according to claim 13, wherein the gas is raw coke oven gas.