An environmentally friendly and energy-saving ammonia recovery device and method for ammonia-containing condensate in coal chemical industry

Abstract

The invention discloses an environmentally friendly and energy-saving ammonia recovery device and method for ammonia-containing condensate in coal chemical industry, comprising a primary stripping tower feed preheater, a primary stripping tower, a stripping gas scrubber, an acid gas heat exchanger, an ammonia-containing condensate tank, a secondary stripping tower, a partial condensate tank, a multi-stage condensation unit, an ammonia refining unit, and an ammonia water preparation unit; the ammonia-containing condensate is firstly concentrated by passing through the primary stripping tower to reduce the processing capacity of the secondary stripping tower, and the concentration of raw materials entering the secondary stripping tower is adjusted to ensure the optimal feed concentration, while reducing investment and energy consumption, high-quality concentrated ammonia water and elemental sulfur are recovered, and the environmental protection hidden danger of ammonia and water in the acid gas flare is solved.

Description

Technical Field

[0001] The present invention belongs to the field of ammonia recovery, and in particular relates to a device and method for recovering ammonia from coal chemical industry ammonia-containing condensate. Background Art

[0002] In the conversion section of a coal chemical plant, the raw coal gas will produce a conversion condensate with a pressure of 3.5-8.0 MPa (G) and a temperature of 35-65°C during the condensation and washing process, containing NH3, CO2, H2S, CO and H2. At present, most companies use the full stripping method to treat this condensate. The acid gas after stripping is sent to the acid gas flare system, and the bottom liquid after stripping is recycled to the gasification device. Due to the high ammonia and water content of the stripping gas, not only the precious ammonia resources are not recovered, but also white smoke is often emitted, and there are certain environmental risks after torch combustion. Due to the different conversion processes, the ammonia content of this condensate is generally 500-4000 mg / L, and there are many impurities in the condensate. If you want to recover high-concentration and high-purity ammonia, the stripping method is used to directly treat this condensate, which requires large equipment, high investment, high energy consumption, and low ammonia recovery value. Summary of the invention

[0003] The purpose of the present invention is to provide an environmentally friendly and energy-saving ammonia recovery device and method for ammonia-containing condensate in coal chemical industry. The ammonia-containing condensate is first concentrated by passing through a primary stripping tower to reduce the processing capacity of a secondary stripping tower. At the same time, the concentration of raw materials entering the secondary stripping tower is adjusted to ensure the optimal feed concentration. While reducing investment and energy consumption, high-quality concentrated ammonia water and elemental sulfur are recovered, solving the environmental protection risk of ammonia and water in the acid gas flare.

[0004] The technical scheme of the present invention is: an environmentally friendly and energy-saving ammonia recovery device for ammonia-containing condensate in coal chemical industry, characterized in that it comprises a primary stripping tower feed preheater, a primary stripping tower, a 1# condensate booster pump, a stripping gas cooler, a stripping gas scrubber, an acid gas heat exchanger, an ammonia-containing condensate tank, an ammonia-containing condensate booster pump, a feed cooler, a primary feed preheater, a secondary feed preheater, a secondary stripping tower, a 2# condensate booster pump, a partial condensate tank, a partial condensate booster pump, a multi-stage condensation unit, an ammonia gas refining unit, and an ammonia water preparation unit;

[0005] The ammonia condensate outside the boundary is divided into two routes through pipelines. One route is passed through the feed preheater of the first-stage stripping tower to the top of the first-stage stripping tower, and the other route is passed through the regulating valve FV1 to the upper part of the ammonia condensate tank.

[0006] The low-pressure steam outside the boundary is introduced into the bottom of the last tray of the first-stage stripping tower through a pipeline, and the vaporized high-flash gas is introduced into the middle tray of the first-stage stripping tower through a pipeline. The bottom of the first-stage stripping tower is connected to the purified water pipeline outside the boundary through the 1# condensate booster pump. The top of the first-stage stripping tower is connected to the acid gas heat exchanger through the first-stage stripping tower feed preheater, and then connected to the stripping gas cooler through the acid gas heat exchanger. The stripping gas cooler is then connected to the lower part of the stripping gas scrubber through a pipeline.

[0007] The demineralized water outside the boundary is introduced into the upper part of the stripping gas washing tower through a pipeline, the bottom of the stripping gas washing tower is connected to the upper part of the ammonia condensate tank through a pipeline, the top of the stripping gas washing tower is connected to the inlet pipeline of the acid gas heat exchanger, and the outlet pipeline of the acid gas heat exchanger is connected to the acid gas desulfurization recovery device outside the boundary;

[0008] The bottom of the ammonia condensate tank is divided into two paths after passing through the ammonia condensate booster pump. One path is connected to the middle of the two upper packings of the secondary stripping tower through the feed cooler, and the other path is connected to the top of the first tray of the secondary stripping tower after passing through the primary feed preheater and the secondary feed preheater respectively.

[0009] The top of the secondary stripping tower is connected to the inlet pipeline of the acid gas heat exchanger, the middle of the secondary stripping tower is connected to the inlet of the primary feed preheater, the bottom of the secondary stripping tower is connected to the inlet of the secondary feed preheater through the 2# condensate booster pump, and the outlet of the secondary feed preheater is connected to the off-site purified water pipeline;

[0010] The outlet of the first-stage feed preheater is connected to the outside ammonia pipeline through a multi-stage condensation unit, an ammonia refining unit, and an ammonia preparation unit; the multi-stage condensation unit is connected to the upper part of the condensate tank, the ammonia refining unit is connected to the upper part of the condensate tank, and the bottom of the condensate tank is connected to the hot feed pipeline of the first-stage feed preheater through a condensate booster pump.

[0011] Furthermore, the nitrogen outside the boundary is introduced into the upper part of the ammonia-containing condensate tank through the regulating valve PV1; the top of the ammonia-containing condensate tank is connected to the flare system through the regulating valve PV2; the steam outside the boundary is connected to the lower part of the secondary stripping tower; and the deionized water outside the boundary is connected to the upper part of the secondary stripping tower.

[0012] Furthermore, the first-stage stripping tower adopts a plate tower with a tower pressure of 0.15-0.35 MPa (G) and a temperature of 125-150°C.

[0013] Furthermore, the stripping gas washing tower adopts a packed tower with a tower pressure of 0.1-0.15 MPa (G), a tower top temperature of 40-50°C, and a tower bottom temperature of 70-80°C.

[0014] Furthermore, a tray is provided at the lower part of the secondary stripping tower, and two sections of packing are provided at the upper part, the tower pressure is 0.5-0.6 MPa (G), the tower top temperature is 45-65°C, and the tower bottom temperature is 160-165°C.

[0015] A method for recovering environmentally friendly and energy-saving ammonia from coal chemical industry ammonia-containing condensate, comprising the following steps:

[0016] Step 1: Feed concentration adjustment

[0017] A stream of condensate with low ammonia concentration is introduced from the ammonia condensate pipeline before entering the feed preheater of the first stripping tower, and directly enters the ammonia condensate tank to mix with the dilute ammonia water from the bottom of the stripping gas scrubber, so that the second stripping tower reaches the optimal feed concentration of 0.8-2wt%;

[0018] Step 2: Safe Discharge Nitrogen Seal

[0019] A stream of nitrogen is introduced into the upper part of the ammonia condensate tank, and the top of the ammonia condensate tank is connected to the flare system through a pipeline. PIC-01 controls the pressure of the ammonia condensate tank at 80-100KPa (G). When the pressure is lower than this value, nitrogen is added through PV1, and the pressure is as high as 150-200KPa (G). It is vented through PV2. After the pressure is reduced, the vent valve is closed;

[0020] Step 3: Primary Stripping

[0021] The ammonia condensate passes through the feed preheater of the first stripping tower and then exchanges heat with the high-temperature ammonia steam at the top of the first stripping tower, and then enters the first tray at the top of the first stripping tower. The low-pressure steam of 0.4-0.6MPa (G) enters from the bottom of the last tray, and the vaporized high flash gas of 0.5-1.0MPa (G) enters from the middle tray. The ammonia condensate is fully in contact with the rising steam on the tray, and mass and heat are transferred. NH3, CO2, H2S, CO, H2 and part of the water vapor in the ammonia condensate are stripped out and leave from the top of the tower. After entering the acid gas heat exchanger for heat exchange, it enters the stripping gas cooler for condensation. The ammonia content is 3-4wt%. The qualified purified water at the bottom of the tower leaves from the bottom of the tower, and the ammonia content is less than 100mg / L.

[0022] Step 4: Stripping gas washing

[0023] The stripping gas condensed to 70-80℃ by the stripping gas cooler enters from the lower part of the stripping gas scrubber, and the deionized water at 35-40℃ enters from the upper part of the packing of the stripping gas scrubber. The gas phase NH3 in the stripping gas fully contacts the deionized water entering from the top of the tower on the packing, and the mass and heat are transferred. The NH3 in the gas phase is fully washed and absorbed, and the acidic non-condensable gas leaves from the top of the tower, and the ammonia condensate leaves from the bottom of the tower.

[0024] Step 5: Secondary stripping

[0025] 75-85% ammonia condensate is used as hot feed, mixed with high-concentration sulfur-containing ammonia liquid from the condensate tank, and heated by the primary feed preheater and the secondary feed preheater to form heating steam, which enters the secondary stripping tower from above the first tray of the secondary stripping tower;

[0026] 15-25% ammonia condensate is used as cold feed. After cooling, it enters the secondary stripping tower from between the two sections of packing at the top of the secondary stripping tower. 1.0-2.0MPa (G) low-pressure steam enters the secondary stripping tower from below the last tray of the secondary stripping tower. The ammonia condensate is fully in contact with the heating steam on the tray, and mass and heat transfer are achieved. NH3, CO2, H2S and part of the water vapor in the condensate are stripped out and enter the upper part of the secondary stripping tower. NH3 and water vapor in the gas phase are washed and absorbed by the cold feed for the first time, and the acid gas moves further to the top of the tower.

[0027] A stream of desalted water at 35-40℃ is introduced from the top of the secondary stripping tower to wash and absorb the NH3 in the acid gas for the second time. The acid gas with ammonia removed after purification is drawn out from the top of the tower; the ammonia-rich gas is extracted from the middle of the secondary stripping tower; the purified water that passes the stripping is drawn out from the bottom of the tower;

[0028] Step 6: Superheating of acid gas

[0029] After the acid gas from the top of the stripping gas scrubber and the top of the secondary stripping tower are mixed in the pipeline, they enter the acid gas heat exchanger and exchange heat with the 120-130°C stripping gas from the primary stripping tower feed preheater. After the temperature of the stripping gas itself rises to 90-110°C, it is discharged to the sulfur recovery device to recover sulfur in the acid gas.

[0030] In the seventh step, the ammonia-rich gas extracted from the middle of the secondary stripping tower passes through a multi-stage condensation unit to obtain crude ammonia, and then passes through an ammonia refining unit to obtain high-purity ammonia, and then enters an ammonia water preparation unit to make high-quality concentrated ammonia water delivery device, wherein the ammonia-containing condensate separated in the multi-stage condensation unit and the ammonia refining unit is mixed in a condensate tank, and the ammonia concentration is 15% to 25%. After being pressurized by a condensate booster pump, it is connected to the hot feed pipeline in front of the primary feed preheater and re-enters the secondary stripping tower for stripping.

[0031] The present invention has the following beneficial effects

[0032] (1) When the ammonia-containing condensate with a pressure of 3.5 to 8.0 MPa (G) enters the ammonia-containing condensate tank after the pressure is released by the regulating valve FV1, a certain amount of non-condensable gas will be volatilized; a stream of nitrogen is introduced into the upper part of the ammonia-containing condensate tank, and the top of the ammonia-containing condensate tank is connected to the flare system through a pipeline. PIC-01 controls the pressure of the ammonia-containing condensate tank at 80 to 100 KPa (G). When the pressure is lower than this value, nitrogen is supplemented through PV1, and the pressure is as high as 150 to 200 KPa (G). It is vented through PV2, and after the pressure is reduced, the vent valve is closed; the present invention discharges the non-condensable gas volatilized from the ammonia-containing condensate to the flare system through a safe discharge nitrogen seal, thereby solving the safety and environmental protection problems caused by on-site discharge.

[0033] (2) The first-stage stripping tower adopts a plate tower with a tower pressure of 0.15-0.35MPa (G) and a temperature of 125-150℃. The ammonia condensate enters the top of the first-stage stripping tower above the first plate after heat exchange with the high-temperature ammonia steam at the top of the tower through the feed preheater. The low-pressure steam of 0.4-0.6MPa (G) enters from the bottom of the last plate, and the vaporized high flash gas of 0.5-1.0MPa (G) enters from the middle plate. The ammonia condensate is fully in contact with the rising steam on the plate, and mass and heat transfer are carried out. NH3, CO2, H2S, CO, H2 and part of the water vapor in the ammonia condensate are stripped out and leave from the top of the tower. The ammonia content is 3-4w t%, qualified purified water leaves the bottom of the tower, and the ammonia content is less than 100mg / L; the present invention performs primary stripping on the condensate with low ammonia content, uses high flash gas as the main heat source, and uses low-pressure steam as the supplementary heat source. Since the high flash gas contains part of ammonia and non-condensable gas, the high flash gas enters the primary stripping tower from the middle tower plate to ensure that the ammonia content of the recycled vaporized condensate meets the standard, and obtains NH3-containing steam with higher concentration at the top of the tower, which enters the next process after condensation in the feed preheater of the primary stripping tower; the present invention uses high flash gas as the main heat source to treat the high flash gas, greatly reduces the consumption of high-quality steam, and also greatly reduces the processing capacity of the subsequent system.

[0034] (3) The stripping gas washing tower adopts a packed tower with a tower pressure of 0.1-0.15 MPa (G), a tower top temperature of 40-50°C, and a tower bottom temperature of 70-80°C. The stripping gas condensed to 70-80°C by the stripping gas cooler enters from the lower part of the stripping gas washing tower, and the deionized water at 35-40°C enters from the upper part of the packing. Most of the NH3 in the stripping gas enters the liquid phase during the condensation process. The gas phase entering the packing is mainly CO2, H2S, CO, H2 and a small amount of NH3, which fully contacts the deionized water entering from the top of the tower on the packing, and mass and heat transfer are carried out. The NH3 in the gas phase is fully washed and absorbed, and the acidic non-condensable gas leaves from the top of the tower, and the ammonia-containing condensate leaves from the bottom of the tower. The present invention reduces the ammonia content in the acid gas to less than 200 ppM and the water content in the acid gas to less than 2% by controlling the flow rate of the deionized water, so as to meet the requirements of entering the sulfur recovery device. The ammonia content of the condensate at the bottom of the tower is 2.5-3.5wt%, and the ammonia-containing condensate is concentrated.

[0035] (4) After the acid gas at the top of the stripping gas scrubber and the top of the secondary stripping tower are mixed in the pipeline, they enter the acid gas heat exchanger and exchange heat with the stripping gas (120-130°C) from the feed preheater of the primary stripping tower. After the temperature of the stripping gas itself rises to 90-110°C, it is discharged to the sulfur recovery device to recover sulfur in the acid gas. The present invention exchanges heat with the high-temperature stripping gas, which not only saves heating steam and circulating cooling water, but also avoids overheating of the acid gas and condensation during pipeline transmission to form ammonium salt crystals that block the pipeline.

[0036] (5) The lower part of the secondary stripping tower is provided with a tray and the upper part is provided with two sections of packing. The tower pressure is 0.5-0.6 MPa (G), the tower top temperature is 45-65°C, and the tower bottom temperature is 160-165°C. About 75-85% of the ammonia-containing condensate is used as hot feed, which is mixed with the high-concentration sulfur-containing ammonia liquid from the condensate tank. After being heated by the two-stage feed preheater, it enters the secondary stripping tower from above the first tray. The remaining about 15-25% of the ammonia-containing condensate is used as cold feed. After being cooled by the feed cooler, it enters the secondary stripping tower from between the two sections of packing at the top. 1.0-2.0 MPa (G) low-pressure steam enters the secondary stripping tower from below the last tray. The ammonia-containing condensate is fully in contact with the heating steam on the tray, and mass and heat transfer are achieved. NH3, CO2, H2S and part of the water in the condensate are removed. The steam is stripped out and enters the packing section, and the NH3 and water vapor in the gas phase are washed and absorbed for the first time by the cold feed, and the acid gas further moves to the top of the tower; a stream of desalted water at 35-40°C is introduced from the top of the tower to wash and absorb the NH3 in the acid gas for the second time, and the acid gas with ammonia removed after purification is drawn out from the top of the tower; ammonia-rich gas is produced from the middle of the secondary stripping tower; purified water qualified by stripping is drawn out from the bottom of the tower; the present invention separates ammonia and acid gas in the condensate in one device, and the ammonia in the acid gas is washed twice by washing liquids of different concentrations, so that the ammonia content in the acid gas is reduced to less than 200 ppM, and the water content is reduced to less than 2%, meeting the requirements for entering the sulfur recovery device, and the ammonia content of the qualified purified water at the bottom of the tower is less than 100 mg / L.

[0037] (6) The optimal ammonia concentration of the feed to the secondary stripping tower is 0.8-2wt%. In order to achieve the optimal feed concentration, a stream of condensate with a low ammonia concentration is introduced from the ammonia-containing condensate pipeline before entering the feed preheater of the primary stripping tower, and directly enters the ammonia-containing condensate tank to mix with the dilute ammonia water from the bottom of the stripping gas washing tower. The present invention controls the amount of condensate directly entering the ammonia-containing condensate tank, thereby controlling the ammonia concentration in the ammonia-containing condensate tank to achieve the optimal feed concentration for the secondary stripping tower.

[0038] (7) After the condensate from the multi-stage condensing unit and the sulfur-containing ammonia liquid from the ammonia refining unit are mixed in the condensate tank, the ammonia concentration is between 15% and 25%. After being pressurized by the condensate booster pump, it is connected to the hot feed pipeline before the first-stage preheater and re-enters the second-stage stripping tower for stripping, so as to avoid the condensate with high ammonia content returning to the ammonia condensate tank and entering the upper absorption section of the second-stage stripping tower through the cold feed pipeline, thereby affecting the washing efficiency of ammonia in the acid gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a schematic diagram of the process of the present invention;

[0040] Explanation of the reference numerals in the accompanying drawings: 1. a first-stage stripping tower feed preheater; 2. a first-stage stripping tower; 3. 1# condensate booster pump; 4. stripping gas cooler; 5. stripping gas washing tower; 6. acid gas heat exchanger; 7. ammonia-containing condensate tank; 8. ammonia-containing condensate booster pump; 9. feed cooler; 10. a first-stage feed preheater; 11. a second-stage feed preheater; 12. a second-stage stripping tower; 13. 2# condensate booster pump; 14. fractional condensate tank; 15. fractional condensate booster pump; 16. multi-stage condensation unit; 17. ammonia refining unit; 18. ammonia water preparation unit. DETAILED DESCRIPTION

[0041] like Figure 1 As shown, an environmentally friendly and energy-saving ammonia recovery device for ammonia-containing condensate in coal chemical industry includes a first-stage stripping tower feed preheater 1, a first-stage stripping tower 2, a 1# condensate booster pump 3, a stripping gas cooler 4, a stripping gas washing tower 5, an acid gas heat exchanger 6, an ammonia-containing condensate tank 7, an ammonia-containing condensate booster pump 8, a feed cooler 9, a first-stage feed preheater 10, a second-stage feed preheater 11, a second-stage stripping tower 12, a 2# condensate booster pump 13, a partial condensate tank 14, a partial condensate booster pump 15, a multi-stage condensation unit 16, an ammonia refining unit 17, and an ammonia water preparation unit 18.

[0042] The ammonia condensate outside the boundary is divided into two paths through pipelines. One path is passed through the first-stage stripping tower feed preheater 1 to the top of the first-stage stripping tower 2, and the other path is passed through the regulating valve FV1 to the upper part of the ammonia condensate tank 7.

[0043] The low-pressure steam outside the boundary is introduced into the bottom of the last tower plate of the first-stage stripping tower 2 through a pipeline, and the vaporized high-flash gas is introduced into the middle tower plate of the first-stage stripping tower 2 through a pipeline. The bottom of the first-stage stripping tower 2 is connected to the purified water pipeline outside the boundary through the 1# condensate booster pump 3. The top of the first-stage stripping tower 2 is connected to the acid gas heat exchanger 6 through the first-stage stripping tower feed preheater 1, and then connected to the stripping gas cooler 4 through the acid gas heat exchanger 6. The stripping gas cooler 4 is then connected to the lower part of the stripping gas washing tower 5 through a pipeline.

[0044] The demineralized water from outside the boundary is introduced into the upper part of the stripping gas washing tower 5 through a pipeline, the bottom of the stripping gas washing tower 5 is connected to the upper part of the ammonia condensate tank 7 through a pipeline, the top of the stripping gas washing tower 5 is connected to the inlet pipeline of the acid gas heat exchanger 6, and the outlet pipeline of the acid gas heat exchanger 6 is connected to the acid gas desulfurization recovery device outside the boundary.

[0045] The nitrogen outside the boundary is introduced into the upper part of the ammonia condensate tank 7 through the regulating valve PV1, and the top of the ammonia condensate tank 7 is connected to the flare system through the regulating valve PV2.

[0046] The bottom of the ammonia-containing condensate tank 7 is divided into two paths after passing through the ammonia-containing condensate booster pump 8. One path is connected to the middle of the two upper fillers of the secondary stripping tower 12 through the feed cooler 9, and the other path is connected to the top of the first layer of the tower plate of the secondary stripping tower 12 after passing through the primary feed preheater 10 and the secondary feed preheater 11 respectively; the out-of-boundary steam is connected to the lower part of the secondary stripping tower 12; the out-of-boundary desalted water is connected to the upper part of the secondary stripping tower 12; the top of the secondary stripping tower 12 is connected to the inlet pipeline of the acid gas heat exchanger 6; the middle part of the secondary stripping tower 12 is connected to the inlet of the primary feed preheater 10; the bottom of the secondary stripping tower 12 is connected to the inlet of the secondary feed preheater 11 through the 2# condensate booster pump 13, and the outlet of the secondary feed preheater 11 is connected to the out-of-boundary purified water pipeline.

[0047] The outlet of the first-stage feed preheater 10 is connected to the outside ammonia pipeline through the multi-stage condensation unit 16, the ammonia refining unit 17, and the ammonia preparation unit 18; (these units all adopt existing technologies and do not need to be explained in detail) the multi-stage condensation unit 16 is connected to the upper part of the condensate tank 14, the ammonia refining unit 17 is connected to the upper part of the condensate tank 14, and the bottom of the condensate tank 14 is connected to the hot feed pipeline of the first-stage feed preheater 10 through the condensate booster pump 15.

[0048] The process is as follows:

[0049] Step 1: Feed concentration adjustment

[0050] The optimal ammonia concentration of the feed to the secondary stripping tower 12 is 0.8-2wt%. In order to achieve the optimal feed concentration, a stream of condensate with a lower ammonia concentration is introduced from the ammonia-containing condensate pipeline before entering the primary stripping tower feed preheater 1, directly enters the ammonia-containing condensate tank 7, and is mixed with the dilute ammonia water from the bottom of the stripping gas washing tower 5.

[0051] Step 2: Safe Discharge Nitrogen Seal

[0052] When the ammonia-containing condensate with a pressure of 3.5-8.0MPa (G) is depressurized through the regulating valve FV1 and enters the ammonia-containing condensate tank 7, a certain amount of non-condensable gas will be volatilized. A stream of nitrogen is introduced into the upper part of the ammonia-containing condensate tank 7. The top of the ammonia-containing condensate tank 7 is connected to the flare system through a pipeline. PIC-01 controls the pressure of the ammonia-containing condensate tank 7 at 80-100KPa (G). When the pressure is lower than this value, nitrogen is supplemented through PV1, and the pressure is as high as 150-200KPa (G). It is vented through PV2. After the pressure is reduced, the vent valve is closed.

[0053] Step 3: Primary Stripping

[0054] The first-stage stripping tower 2 adopts a plate tower with a tower pressure of 0.15-0.35MPa (G) and a temperature of 125-150°C. The ammonia-containing condensate enters the first layer of tower plates at the top of the first-stage stripping tower 2 after heat exchange with the high-temperature ammonia steam at the top of the tower through the first-stage stripping tower feed preheater 1. The low-pressure steam of 0.4-0.6MPa (G) enters from the bottom of the last tower plate, and the vaporized high flash gas of 0.5-1.0MPa (G) enters from the middle tower plate. The ammonia-containing condensate is fully contacted with the rising steam on the tower plate for mass and heat transfer. NH3, CO2, H2S, CO, H2 and part of the water vapor in the ammonia-containing condensate are stripped out and leave from the top of the tower. After entering the acid gas heat exchanger for heat exchange, it enters the stripping gas cooler for condensation. The ammonia content is 3-4wt%. The qualified purified water at the bottom of the tower leaves from the bottom of the tower, and the ammonia content is <100mg / L.

[0055] Step 4: Stripping gas washing

[0056] The stripping gas washing tower 5 adopts a packed tower with a tower pressure of 0.1-0.15 MPa (G), a tower top temperature of 40-50°C, and a tower bottom temperature of 70-80°C. The stripping gas condensed to 70-80°C by the stripping gas cooler 4 enters from the lower part of the stripping gas washing tower 5, and the deionized water at 35-40°C enters from the upper part of the packing of the stripping gas washing tower 5. Most of the NH3 in the stripping gas enters the liquid phase during the condensation process. The gas phase entering the packing is mainly CO2, H2S, CO, H2 and a small amount of NH3, which is fully in contact with the deionized water entering from the top of the tower on the packing, mass transfer and heat transfer, the NH3 in the gas phase is fully washed and absorbed, the acidic non-condensable gas leaves from the top of the tower, and the ammonia-containing condensate leaves from the bottom of the tower.

[0057] Step 5: Secondary stripping

[0058] The secondary stripping tower 12 is provided with a tray at the bottom and two sections of packing at the top, with a tower pressure of 0.5-0.6 MPa (G), a tower top temperature of 45-65°C, and a tower bottom temperature of 160-165°C;

[0059] About 75-85% of the ammonia condensate is used as hot feed, mixed with the high-concentration sulfur-containing ammonia liquid from the condensate tank 14, and heated by the primary feed preheater 10 and the secondary feed preheater 11 to form heating steam, which enters the secondary stripping tower 12 from above the first layer of the tower plate;

[0060] About 15-25% of ammonia condensate is used as cold feed. After being cooled, it enters the secondary stripping tower 12 from between the two sections of packing at the upper part of the secondary stripping tower 12. 1.0-2.0 MPa (G) low-pressure steam enters the secondary stripping tower 12 from below the last tray. The ammonia condensate is fully in contact with the heating steam on the tray, and mass and heat transfer are performed. NH3, CO2, H2S and part of the water vapor in the condensate are stripped out and enter the upper packing section. NH3 and water vapor in the gas phase are first washed and absorbed by the cold feed, and the acid gas further moves to the top of the tower.

[0061] A stream of desalted water at 35-40°C is introduced from the top of the tower to perform a second washing and absorption on NH3 in the acidic gas. The acidic gas with ammonia removed after purification is drawn out from the top of the tower; ammonia-rich gas is extracted from the middle of the secondary stripping tower 12; purified water that passes the stripping process is drawn out from the bottom of the tower.

[0062] Step 6: Superheating of acid gas

[0063] The acid gas from the top of the stripping gas scrubber 5 and the top of the secondary stripping tower 12 are mixed in the pipeline and enter the acid gas heat exchanger 6 to exchange heat with the stripping gas (120-130°C) from the primary stripping tower feed preheater 1. After its own temperature rises to 90-110°C, it is discharged to the sulfur recovery device to recover sulfur in the acid gas.

[0064] In the seventh step, the ammonia-rich gas extracted from the middle of the secondary stripping tower passes through a multi-stage condensation unit to obtain crude ammonia gas, and then passes through an ammonia refining unit to obtain high-purity ammonia gas, and then enters an ammonia water preparation unit to make high-quality concentrated ammonia water delivery device; wherein the ammonia-containing condensate separated in the multi-stage condensation unit and the ammonia refining unit is mixed in the condensate tank 14, and the ammonia concentration is 15% to 25%. After being pressurized by the condensate booster pump 15, it is connected to the hot feed pipeline in front of the primary feed preheater 10 and re-enters the secondary stripping tower 12 for stripping, so as to avoid the condensate with a high ammonia content from entering the upper absorption section of the secondary stripping tower 12 through the ammonia-containing condensate tank 7 and the cold feed pipeline, thereby affecting the washing efficiency of ammonia in the acid gas.

Claims

1. An environmentally friendly and energy-saving ammonia recovery device for ammonia-containing condensate in coal chemical industry, characterized in that: It comprises a first-stage stripping tower feed preheater (1), a first-stage stripping tower (2), a No. 1 condensate booster pump (3), a stripping gas cooler (4), a stripping gas scrubber (5), an acid gas heat exchanger (6), an ammonia-containing condensate tank (7), an ammonia-containing condensate booster pump (8), a feed cooler (9), a first-stage feed preheater (10), a second-stage feed preheater (11), a second-stage stripping tower (12), a No. 2 condensate booster pump (13), a partial condensate tank (14), a partial condensate booster pump (15), a multi-stage condensation unit (16), an ammonia gas refining unit (17), and an ammonia water preparation unit (18); The ammonia-containing condensate outside the boundary is divided into two paths through pipelines. One path passes through the primary stripping tower feed preheater (1) and enters the first tray above the primary stripping tower (2). The other path passes through the regulating valve FV1 and enters the upper part of the ammonia-containing condensate tank (7). The low-pressure steam from outside the boundary is introduced into the lower part of the last tray of the first-stage stripping tower (2) through a pipeline, and the high-flash gas from vaporization is introduced into the middle tray of the first-stage stripping tower (2) through a pipeline. The bottom of the first-stage stripping tower (2) is connected to the purified water pipeline from outside the boundary through the 1# condensate booster pump (3). The top of the first-stage stripping tower (2) is connected to the acid gas heat exchanger (6) through the first-stage stripping tower feed preheater (1), and then connected to the stripping gas cooler (4) through the acid gas heat exchanger (6). The stripping gas cooler (4) is further connected to the lower part of the stripping gas scrubber (5) through a pipeline. The deionized water from outside the boundary is introduced into the upper part of the stripping gas washing tower (5) through a pipeline, the bottom of the stripping gas washing tower (5) is connected to the upper part of the ammonia condensate tank (7) through a pipeline, the top of the stripping gas washing tower (5) is connected to the inlet pipeline of the acid gas heat exchanger (6), and the outlet pipeline of the acid gas heat exchanger (6) is connected to the acid gas desulfurization recovery device outside the boundary; The bottom of the ammonia condensate tank (7) is divided into two paths after passing through the ammonia condensate booster pump (8), one path is connected to the middle of the two upper packings of the secondary stripping tower (12) through the feed cooler (9), and the other path is connected to the top of the first tray of the secondary stripping tower (12) after passing through the primary feed preheater (10) and the secondary feed preheater (11); The top of the secondary stripping tower (12) is connected to the inlet pipeline of the acid gas heat exchanger (6), the middle of the secondary stripping tower (12) is connected to the inlet of the primary feed preheater (10), the bottom of the secondary stripping tower (12) is connected to the inlet of the secondary feed preheater (11) through the 2# condensate booster pump (13), and the outlet of the secondary feed preheater (11) is connected to the external purified water pipeline; The outlet of the primary feed preheater (10) is connected to an off-site ammonia pipeline via a multi-stage condensing unit (16), an ammonia refining unit (17), and an ammonia preparation unit (18); wherein the multi-stage condensing unit (16) is connected to the upper part of the condensate tank (14), the ammonia refining unit (17) is connected to the upper part of the condensate tank (14), and the bottom of the condensate tank (14) is connected to the hot feed pipeline of the primary feed preheater (10) via a condensate booster pump (15).

2. The environmentally friendly and energy-saving ammonia recovery device for coal chemical ammonia-containing condensate according to claim 1, characterized in that: The nitrogen from outside the boundary is introduced into the upper part of the ammonia condensate tank (7) through the regulating valve PV1; the top of the ammonia condensate tank (7) is connected to the flare system through the regulating valve PV2; the steam from outside the boundary is connected to the lower part of the secondary stripping tower (12); and the deionized water from outside the boundary is connected to the upper part of the secondary stripping tower (12).

3. The environmentally friendly and energy-saving ammonia recovery device for coal chemical ammonia-containing condensate according to claim 1, characterized in that: The first-stage stripping tower (2) is a plate tower with a tower pressure of 0.15-0.35 MPa (G) and a temperature of 125-150°C.

4. The environmentally friendly and energy-saving ammonia recovery device for coal chemical ammonia-containing condensate according to claim 1, characterized in that: The stripping gas washing tower (5) is a packed tower with a tower pressure of 0.1-0.15 MPa (G), a tower top temperature of 40-50°C, and a tower bottom temperature of 70-80°C.

5. The environmentally friendly and energy-saving ammonia recovery device for coal chemical ammonia-containing condensate according to claim 1, characterized in that: The secondary stripping tower (12) is provided with a tower plate at the bottom and two stages of packing at the top. The tower pressure is 0.5-0.6 MPa (G), the tower top temperature is 45-65°C, and the tower bottom temperature is 160-165°C.

6. An environmentally friendly and energy-saving ammonia recovery method for ammonia-containing condensate in coal chemical industry, characterized in that: The environmentally friendly and energy-saving ammonia recovery device for coal chemical ammonia-containing condensate according to any one of claims 1 to 5 comprises the following steps: Step 1: Feed concentration adjustment A stream of condensate with a low ammonia concentration is introduced from the ammonia condensate pipeline before entering the feed preheater (1) of the first stripping tower, and directly enters the ammonia condensate tank (7) to mix with the dilute ammonia water from the bottom of the stripping gas scrubber (5), so that the second stripping tower (12) reaches the optimal feed concentration of 0.8-2wt%; Step 2: Safe Discharge Nitrogen Seal A stream of nitrogen is introduced into the upper part of the ammonia condensate tank (7), and the top of the ammonia condensate tank (7) is connected to the flare system through a pipeline. PIC-01 controls the pressure of the ammonia condensate tank (7) at 80 to 100 kPa (G). When the pressure is lower than this value, nitrogen is added through the regulating valve PV1. When the pressure is raised to 150 to 200 kPa (G), the tank is vented through the regulating valve PV2. After the pressure is reduced, the vent valve is closed; Step 3: Primary Stripping The ammonia-containing condensate passes through the first stripping tower feed preheater (1) and exchanges heat with the high-temperature ammonia steam at the top of the first stripping tower (2), and then enters the first tray at the top of the first stripping tower (2). The low-pressure steam of 0.4-0.6 MPa (G) enters from the bottom of the last tray, and the vaporized high-pressure flash gas of 0.5-1.0 MPa (G) enters from the middle tray. The ammonia-containing condensate and the rising steam are fully contacted on the tray to transfer mass and heat. NH3, CO2, H2S, CO, H2 and part of the water vapor in the ammonia-containing condensate are stripped out and leave from the top of the tower. After entering the acid gas heat exchanger (6) for heat exchange, it enters the stripping gas cooler (4) for condensation. The ammonia content is 3-4 wt%. The qualified purified water at the bottom of the tower leaves from the bottom of the tower, and the ammonia content is less than 100 mg / L. Step 4: Stripping gas washing The stripping gas condensed to 70-80°C by the stripping gas cooler (4) enters from the lower part of the stripping gas scrubber (5), and the deionized water at 35-40°C enters from above the packing of the stripping gas scrubber (5). The gas phase NH3 in the stripping gas fully contacts the entering deionized water on the packing, and mass and heat transfer are achieved. The NH3 in the gas phase is fully washed and absorbed, and the acidic non-condensable gas leaves from the top of the tower, and the ammonia-containing condensate leaves from the bottom of the tower. Step 5: Secondary stripping 75-85% ammonia-containing condensate is used as hot feed, mixed with high-concentration sulfur-containing ammonia liquid from the condensate tank (14), and heated by the primary feed preheater (10) and the secondary feed preheater (11) to form heating steam, which enters the secondary stripping tower (12) from above the first tray of the secondary stripping tower (12); Ammonia-containing condensate of 15-25% is used as cold feed, and after being cooled, enters the secondary stripping tower (12) from between two sections of packing at the upper part of the secondary stripping tower (12), and 1.0-2.0 MPa (G) low-pressure steam enters the secondary stripping tower (12) from below the last tray of the secondary stripping tower (12); the ammonia-containing condensate is fully in contact with the heating steam on the tray, and mass and heat transfer are performed, and NH3, CO2, H2S and part of the water vapor in the condensate are stripped out and enter the upper part of the secondary stripping tower (12), and NH3 and water vapor in the gas phase are first washed and absorbed by the cold feed, and the acid gas further moves to the top of the tower; A stream of desalted water at 35-40°C is introduced from the top of the secondary stripping tower (12) to perform a second washing and absorption of NH3 in the acid gas. The acid gas after purification and removal of ammonia is drawn out from the top of the tower; ammonia-rich gas is extracted from the middle of the secondary stripping tower (12); purified water that passes the stripping process is drawn out from the bottom of the tower; Step 6: Superheating of acid gas The acid gas from the top of the stripping gas scrubber (5) and the top of the secondary stripping tower (12) are mixed in the pipeline and then enter the acid gas heat exchanger (6) to exchange heat with the 120-130° C. stripping gas from the primary stripping tower feed preheater (1). After the temperature of the acid gas is raised to 90-110° C., the acid gas is discharged to the sulfur recovery device to recover sulfur in the acid gas. In the seventh step, the ammonia-rich gas extracted from the middle of the secondary stripping tower (12) passes through a multi-stage condensation unit to obtain crude ammonia gas, and then passes through an ammonia refining unit to obtain high-purity ammonia gas, and then enters an ammonia water preparation unit to produce high-quality concentrated ammonia water for delivery. The ammonia-containing condensate separated in the multi-stage condensation unit and the ammonia refining unit is mixed in a condensate tank (14) with an ammonia concentration of 15% to 25%. After being pressurized by a condensate booster pump (15), it is connected to the hot feed pipeline in front of the primary feed preheater (10) and re-enters the secondary stripping tower (12) for stripping.

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