Device for recovering ammonia from coal gasification ammonia-nitrogen-containing condensate

Abstract

The utility model discloses a device for recovering ammonia from coal gasification ammonia-nitrogen-containing condensate, which is characterized in that a heat exchanger pipeline is connected with a stripping tower inlet heat exchanger, and the stripping tower inlet heat exchanger is connected with the upper part of a stripping tower; the top of the stripping tower is connected with the lower part of a deacidification tower through a pipeline; the bottom of the deacidification tower is connected with a stripping tower inlet heat exchanger through a deamination tower bottom pump; and the stripping tower inlet heat exchanger is respectively connected with the deamination tower, the deacidification tower and the stripping tower through pipelines. The top of the deamination tower is connected to an ammonia water tank after being connected through a cooler group. The bottom of the deamination tower is connected with a heat exchanger through a pipeline; and the stripping tower inlet heat exchanger is connected with the deamination tower after being connected with the heat exchanger through a pipeline. By adopting the method, the CO2 component in the original acid gas is greatly reduced, so that the consumption of ammonia recovery liquid alkali is reduced; secondly, along with reduction of the addition amount of the alkali liquor, generation of impurities such as ferrous sulfide is reduced, and the ammonia recovery ammonia water quality is improved; in addition, ammonia is recycled to prepare ammonia water, and acid gas in the wastewater is further recycled and fed into sulfur to recycle byproduct sulfuric acid.

Description

Technical Field

[0001] The utility model relates to a device for recovering ammonia from coal gasification condensate containing ammonia nitrogen, and belongs to the technical field of ammonia recovery. Background Art

[0002] In the ammonia recovery process, the traditional one is a single-tower or double-tower ammonia recovery process, that is, the condensate is stripped by the stripping tower, cooled by the heat exchanger, and the condensed acid liquid is sent to the ammonia recovery for stripping, and finally sent to the distillation system to recover ammonia water. In addition, industrial caustic soda (mass concentration is 48%) is purchased and pumped to the static mixer by the alkali liquid pump, mixed evenly with the ammonia-containing wastewater in the static mixer, and then enters the ammonia recovery stripping distillation system.

[0003] Ammonia-containing wastewater enters the ammonia stripping tower, and the liquid is heated by the steam directly entering the tower at the bottom of the tower. The material coming out of the top of the tower can be condensed by the condensation system to obtain 18%-25% ammonia water. After deammoniation, the ammonia content in the wastewater can be reduced to below 1 mg / l. The wastewater leaves the ammonia stripping tower from the bottom, and after heat exchange and cooling with the material entering the tower through the heat exchanger, it is discharged from the distillation system by the discharge pump and sent to sewage treatment.

[0004] A large amount of non-condensable gas and acid gas in the conversion condensate are removed by neutralization with alkali solution. Due to the need to maintain a high alkalinity, the ratio of alkali solution consumption to the amount of waste liquid treated is about 1:5, and the alkali solution consumption is relatively high.

[0005] The single-tower gas stripping process has a cooler and a separation tank at the top of the stripping tower. Since the temperature at the top of the stripping tower is 110-120°C and the pressure is between 0.1-0.2Mpa, the stripping gas contains CO 2 , H 2 Acidic gases such as S can cause certain corrosion to equipment and pipelines. Summary of the invention

[0006] In view of the problems in the prior art, the utility model provides a device for recovering ammonia from ammonia-nitrogen condensate from coal gasification. The device can reduce the consumption of neutralizing alkali solution, improve the quality of ammonia water, avoid corrosion of the equipment and pipelines on the top of the stripping tower, and reduce environmental pollution caused by exhaust gas.

[0007] In order to achieve the above technical objectives, the technical solution of the utility model is:

[0008] A device for recovering ammonia from coal gasification condensate containing ammonia nitrogen, wherein the acid water outlet pipe of the deacidification tower kettle and the inlet heat exchanger pipe of the stripping tower are connected with the acid water inlet and outlet pipes of the stripping tower inlet.

[0009] The heat exchanger pipeline at the deacidification tower kettle outlet and the stripping tower inlet is connected to the shell side inlet of the deacidification tower reflux cooler, and the outlet pipeline of the deacidification tower reflux cooler is connected to the lower inlet of the deacidification tower packing.

[0010] The heat exchanger pipe of the acid water outlet from the deacidification tower kettle and the stripping tower inlet is connected to the upper inlet of the deamination tower packing.

[0011] The acid water pipeline of the heat exchanger at the inlet of the stripping tower is connected to the upper inlet of the packing layer of the stripping tower.

[0012] The desalted water is connected to the upper inlet of the packing layer of the deacidification tower.

[0013] The cooling water inlet pipe of the circulating water inner cooler at the top of the deamination tower is connected to the bottom inlet of the circulating water inner cooler, and the cooling water outlet pipe of the circulating water inner cooler at the top of the deamination tower is connected to the upper outlet of the circulating water inner cooler.

[0014] The utility model discloses a three-tower process for recovering ammonia from acidic water, namely, a stripping tower, a deacidification tower and a deammonification tower. Acidic water enters the system and passes through the stripping tower, the deacidification tower and finally the deammonification tower.

[0015] In some embodiments, the deacidification tower bottom liquid enters the stripping tower inlet heat exchanger tube side, the acidic water enters the shell side, and enters the upper inlet of the stripping tower packing layer after heat exchange.

[0016] In some embodiments, the stripping tower is a packed tower, the tower body is made of stainless steel, the packing is ball ring, and the packing layer height is 4000mm-4500mm.

[0017] The deacidification tower body is made of stainless steel, and the tower plate adopts a plate tower or a bubble tower, which is arranged in 8-10 layers. A packing layer is installed on the upper part of the tower plate, and the packing adopts Raschig ring.

[0018] The deamination tower is a packed tower with a stainless steel body and a stainless steel circulating water inner cooler on the top. The packing is regular packing, divided into 4-6 layers.

[0019] The cooling medium of the deacidification tower reflux cooler, the deamination tower top circulating water internal cooler and the deamination tower top cooler group all adopts pipeline circulating water.

[0020] In view of the above technical solution, the utility model provides a method for recovering ammonia from coal gasification condensate containing ammonia nitrogen, comprising the following steps:

[0021] (1) The condensate water containing ammonia nitrogen is heated and then passed into the stripping tower for stripping. The top gas of the stripping tower is sent to the lower part of the deacidification tower with steam as secondary stripping gas to remove acid gas;

[0022] (2) Desalted water is introduced into the top of the deacidification tower as washing water to wash ammonia in the stripping steam of the absorption gas. The acidic water in the bottom of the tower after the acid gas is removed is pumped to the heat exchanger for heat exchange. The acidic water after heat exchange is divided into three streams, 20% of which is sent to the deamination tower for distillation to produce ammonia water, 60% is sent to the deacidification tower for circulating washing after cooling, and 20% is mixed with condensate water containing ammonia nitrogen and enters the stripping tower for recycling;

[0023] (3) After stripping in the deamination tower, the ammonia-containing gas phase material gradually rises and is enriched in the tower. Part of it is condensed as reflux in the tower, and part of it is evaporated from the top of the tower. The material coming out of the top of the tower is cooled in turn, and the ammonia water produced is sent to the ammonia water tank.

[0024] The physical and chemical properties of the condensate water containing ammonia nitrogen in step (1) are as follows: temperature of 60°C, pressure of 0.3 MPa (A), ammonia content of 1%-4% (mass concentration), H2S content of 200-400 ppm, CO2 content of 5%, and carbon monoxide content of 0.2-0.25%.

[0025] In step (1), 0.5-0.8 MPa steam is passed through the bottom of the tower for gas stripping, and the acid gas is stripped out and then sent to a deacidification tower for removal of the acid gas.

[0026] After the acid gas is removed in step (2), the acid water in the bottom of the tower is heat exchanged to a temperature of 80-90°C, 20% of which is sent to the deamination tower for distillation to produce ammonia water; 60% is sent to the deacidification tower for circulating washing; and 20% is sent to the stripping tower for recycling.

[0027] Before being sent to the deamination tower, liquid alkali is added and then the heat is exchanged to 90℃ again before entering the deamination tower.

[0028] The bottom liquid of the stripping tower is pumped to gasification, the acid gas at the top of the deacidification tower is sent to sulfur recovery as a byproduct of sulfuric acid, the ammonia-containing water from the bottom of the deacidification tower enters the upper part of the deamination tower, and the lower part of the deamination tower uses 0.5-0.8Mpa steam for stripping. The gas phase material mainly composed of ammonia gradually rises and enriches in the tower, and part of the material is condensed by the top circulating water cooler as reflux in the tower, and part is evaporated from the top of the tower. The materials coming out of the top of the tower are cooled by the water cooler in turn, and 18%-25% ammonia water is produced and sent to the ammonia water tank. The ammonia content of the wastewater at the bottom of the deamination tower is reduced to below 1ppm, and it is sent to the sulfur recovery tail gas washing tower after cooling by the deamination tower inlet heat exchanger.

[0029] The bottom liquid of the deacidification tower is pumped to the heat exchanger at the inlet of the stripping tower. After heat exchange, it is divided into three streams. 20% of the liquid is removed from the ammonia and recovered to the ammonia distillation tower, 60% is refluxed to the deacidification tower, and 20% is mixed with the conversion condensate and enters the heat exchanger at the inlet of the stripping tower. Then, it is recirculated into the stripping tower after heat exchange at the inlet of the stripping tower.

[0030] The concentration of caustic soda neutralized in the deamination tower is 48%.

[0031] It can be seen from the above description that the utility model has the following advantages:

[0032] (1) After the acidic water passes through the three-tower process, the acidic gas components such as CO2 and H2S in the original ammonia-containing wastewater are reduced, thereby reducing the consumption of liquid alkali in ammonia recovery.

[0033] (2) Due to the reduction of the amount of neutralizing alkali solution added to the deacidification tower, the generation of impurities such as ferrous sulfide is reduced, and the quality of ammonia water recovered from ammonia is improved.

[0034] (3) Ammonia is recycled and made into ammonia water, which generates certain economic value. The ammonia-containing wastewater is further treated to remove acidic gases, so that the acidic gases in the wastewater can be recovered to produce sulfuric acid as a by-product, thereby reducing the environmental pollution of the waste gas and generating certain benefits.

[0035] (4) The bottom effluent of the deacidification tower is directly discharged to the tail gas washing tower for sulfur recovery. On the one hand, the high pH value of the wastewater from the deacidification tower increases the difficulty of sewage treatment; on the other hand, the sulfur recovery alkaline solution washing has a better washing effect than ammonia water washing.

[0036] (5) A portion of the deacidification tower bottom liquid is cooled and refluxed to the conversion stripping tower, so that the acid gas in the acidic water can be removed more thoroughly. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 The invention relates to a device for recovering ammonia from coal gasification condensate containing ammonia nitrogen, which comprises: 1. a stripping tower; 2. a deacidification tower; 3. a deamination tower; 4. an ammonia water tank; 5. a deamination tower bottom pump; 6. a stripping tower inlet heat exchanger; 7. a deacidification tower reflux cooler; 8. a cooler group; 9. a heat exchanger; 10. an alkali solution pipeline; 11. a heat exchanger pipeline; 12. a steam inlet pipeline for the deamination tower; 13. a low-pressure steam inlet pipeline for the stripping tower; 14. a circulating pump; 15. a pipeline for desalted water from the pipeline network to enter the deacidification tower; and 16. a deamination tower top outlet pipeline. DETAILED DESCRIPTION

[0038] The method of the utility model is further described in detail below based on the drawings and embodiments.

[0039] Example 1

[0040] like Figure 1 The device shown is a device for recovering ammonia from coal gasification condensate containing ammonia nitrogen, wherein the heat exchanger pipeline 11 is connected to the stripping tower inlet heat exchanger 6, and the stripping tower inlet heat exchanger 6 is connected to the upper part of the stripping tower 1;

[0041] The top of the stripping tower 1 is connected to the lower part of the deacidification tower 2 via a pipeline, and the bottom of the deacidification tower 2 is connected to the stripping tower inlet heat exchanger 6 via a deamination tower bottom pump 5;

[0042] The stripping tower inlet heat exchanger 6 is connected to the deamination tower 3, the deacidification tower 2 and the stripping tower 1 through pipelines.

[0043] The top of the deammonification tower 3 is connected to the ammonia water tank 4 through a cooler group 8 .

[0044] The bottom of the deamination tower 3 is connected to the heat exchanger 9 via a pipeline; the stripping tower inlet heat exchanger 6 is connected to the heat exchanger 9 via a pipeline and then connected to the deamination tower 3.

[0045] A liquid caustic soda pipeline 10 is provided on the pipeline before the stripping tower inlet heat exchanger 6 is connected to the heat exchanger 9 .

[0046] A reflux cooler 7 is provided on the pipeline from the stripping tower inlet heat exchanger 6 to the deacidification tower 2 .

[0047] Example 2

[0048] The device of Example 1 is used to carry out the following process:

[0049] The physical and chemical properties of the condensate water containing ammonia nitrogen in the present invention are as follows: temperature is 60°C, pressure is 0.3Mpa (A), ammonia content is 1%-4% (mass concentration), H 2 S content is 200-400ppm, CO 2 The content is 5.0-6.0%, and the carbon monoxide content is 0.2-0.25%.

[0050] A method for recovering ammonia from coal gasification condensate containing ammonia nitrogen, comprising the following steps:

[0051] (1) 0.15Mpa, 115℃, 4000kg / h acidic water enters the deacidification tower. Flash steam from the stripping tower controls the top temperature of the deacidification tower to 90℃ and the pressure to 0.14Mpa. The top acid gas (NH3: 500ppm, H2S: 2000ppm, CO2: 45%) is sent to the flare or sulfur recovery. The bottom temperature of the deacidification tower is 100℃ and the pressure is 0.15Mpa.

[0052] (2) After the acid gas is removed, the acid water in the bottom of the tower is pressurized to 1.2Mpa by a pump and then sent to the inlet heat exchanger for heat exchange. The acid water after heat exchange is divided into three streams. 20% is sent to the ammonia distillation tower for distillation to produce ammonia water, 60% is cooled to 40℃ by a water cooler and then sent to the middle of the deacidification tower for circulation washing, the top of the tower is washed with desalted water, and 20% is mixed with the conversion condensate and enters the stripping tower for recycling.

[0053] H in the acidic water at the deacidification tower 2 The S content is 400ppm, CO 2 The content is 50000ppm. This system uses a three-stream split method to further remove CO from acidic water. 2 , H 2 The first stream is pumped from the bottom of the deacidification tower to the water cooler for cooling, and then enters the deacidification tower for circulation to remove CO in the acidic water. 2 , can be reduced to 300ppm, and can remove more than 95% of CO 2 .

[0054] The second stream is pumped to the stripping tower through the bottom pump of the deacidification tower. Before this pipeline is set up, the acidic water H 2The sulfur content is 400ppm. Hydrogen sulfide is carried into the deamination tower and the subsequent system to generate FeS, causing the ammonia water to appear black and green, affecting the product quality. 20% acidic water is sent to the stripping tower to further remove H 2 S to 6ppm, thereby improving product quality. The third stream is the feed for the deamination tower.

[0055] (3) After the acid gas is removed, the condensate is neutralized with alkali (48% liquid alkali), and the pH is controlled at 11.5-12.5 before entering the deamination tower. The flash gas at the top of the deamination tower is condensed step by step in the cooler and then sent to the ammonia water tank. The deamination tower uses 0.5MPa steam stripping.

[0056] (4) The bottom effluent of the deacidification tower is directly discharged to the tail gas washing tower for sulfur recovery. On the one hand, the high pH value of the wastewater from the deacidification tower increases the difficulty of sewage treatment; on the other hand, the sulfur recovery alkaline solution washing has a better washing effect than ammonia water washing.

[0057] The technical effects achieved by adopting the technical solution of the present invention are:

[0058] (1) Prepare high-quality ammonia water and ensure that H 2 S≤1ppm, condense and separate the ammonia in the produced gas. 3 The gaseous ammonia is quenched, refined and adsorbed to obtain an ammonia concentration of ≥99.9%, H 2 Ammonia water with an S content of less than 1ppm and a concentration of about 15% can avoid the accumulation of sulfur and ammonia nitrogen in the system due to unstable operation in traditional processes.

[0059] (2) Obvious economic and environmental benefits: Recycled NH 3 It can be made into liquid ammonia or ammonia water for reuse, which has high economic value. After the pure water from the ammonia evaporation tower of this project meets the standards, part of it is used for self-use, and the rest is sent out for gasification, achieving "zero discharge" of wastewater, which has a good environmental effect. The separation process is entirely physical, and the separation is simple and thorough. The consumption of alkali liquid auxiliary material is 40kg / kg condensate, which greatly reduces the operating cost.

[0060] It is understandable that the above specific description of the utility model is only used to illustrate the utility model and is not limited to the technical solution described in the embodiment of the utility model. Those skilled in the art should understand that the utility model can still be modified or replaced by equivalents to achieve the same technical effect; as long as the use requirements are met, they are within the protection scope of the utility model.

Claims

1. A device for recovering ammonia from coal gasification condensate containing ammonia nitrogen, characterized in that: The heat exchanger pipeline (11) is connected to the stripping tower inlet heat exchanger (6), and the stripping tower inlet heat exchanger (6) is connected to the upper part of the stripping tower (1); The top of the stripping tower (1) is connected to the lower part of the deacidification tower (2) via a pipeline, and the bottom of the deacidification tower (2) is connected to the stripping tower inlet heat exchanger (6) via a deamination tower bottom pump (5); The stripping tower inlet heat exchanger (6) is connected to the deamination tower (3), the deacidification tower (2), and the stripping tower (1) through pipelines.

2. The device for recovering ammonia from coal gasification condensate containing ammonia nitrogen according to claim 1, characterized in that: The top of the deammonification tower (3) is connected to the ammonia water tank (4) via a cooler group (8).

3. The device for recovering ammonia from coal gasification condensate containing ammonia nitrogen according to claim 1, characterized in that: The bottom of the deamination tower (3) is connected to the heat exchanger (9) via a pipeline; the heat exchanger (6) at the inlet of the stripping tower is connected to the heat exchanger (9) via a pipeline and then connected to the deamination tower (3).

4. The device for recovering ammonia from coal gasification condensate containing ammonia nitrogen according to claim 3, characterized in that: A liquid caustic soda pipeline (10) is provided on the pipeline before the stripping tower inlet heat exchanger (6) is connected to the heat exchanger (9).

5. The device for recovering ammonia from coal gasification condensate containing ammonia nitrogen according to claim 1, characterized in that: A reflux cooler (7) is provided on the pipeline from the stripping tower inlet heat exchanger (6) to the deacidification tower (2).

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