Environment-friendly and efficient oxidation process desulfurization regeneration tail gas treatment system and method thereof

Abstract

The invention belongs to the technical field of coke oven gas purification, and particularly relates to an environment-friendly and efficient oxidation process desulfurization regeneration tail gas treatment system and a method thereof.The system is characterized in that the system is a multi-stage step-by-step washing system and comprises an alkaline washing tower, an acid washing tower and a water washing tower, and a regeneration tail gas inlet pipe is connected to the bottom of the alkaline washing tower; primary washing tail gas at the top of the alkaline washing tower is connected with the bottom of the pickling tower through a pipeline, secondary washing tail gas at the top of the pickling tower is connected with the bottom of the water washing tower through a pipeline, a bleeder is arranged at the top of the water washing tower, the bottom of the bleeder is isolated from the interior of the water washing tower through a partition plate, and an overpressure return pipe is arranged between an outlet of the tail gas fan and the bleeder and provided with a switch valve. And a pressure gauge is arranged on an outlet pipeline of the tail gas fan and is in interlocking control with the switching valve. The method has the beneficial effects that the existing environmental protection standard can be met, ammonia in the tail gas can be recycled, no sewage is discharged, and the method has the characteristics of environmental protection, high efficiency, stable and reliable process and easiness in implementation and popularization.

Description

Technical Field

[0001] The invention belongs to the technical field of coke oven gas purification, and in particular relates to an environmentally friendly and efficient oxidation desulfurization regeneration tail gas treatment system and method. Background Art

[0002] Wet oxidation is a widely used coke oven gas desulfurization process with the advantages of high desulfurization efficiency, low catalyst dosage, low operating cost, and low one-time investment. Its main process principle is to absorb acidic components such as H2S in the gas through cyclic spraying of desulfurization liquid, and then convert it into sulfur products under the action of oxygen in the regeneration tower or regeneration tank for recovery. The air used for regeneration not only has an oxidizing effect, but also the precipitated sulfur adheres to the air bubbles, playing the role of flotation sulfur foam. Due to contact with the ammonia-containing desulfurization liquid, the desulfurization regeneration tail gas contains a certain amount of harmful substances such as ammonia and H2S. Direct discharge will pollute the environment and cause serious harm. Therefore, it is of great significance to achieve harmless treatment of desulfurization regeneration tail gas.

[0003] The Chinese invention patent with announcement number CN111088083A discloses a system and process for reducing the emission of desulfurization regeneration tail gas, in which the regenerated tail gas is pressurized and used as the gas source to enter the regeneration tower of the next stage of desulfurization, and the emission is reduced by reusing the regenerated tail gas.

[0004] The Chinese invention patent with announcement number CN202010248989.3CN111088083A discloses a process for treating desulfurization regeneration tail gas using a tubular furnace, in which the regenerated tail gas is sent into the tubular furnace with air distribution and reburning by a fan.

[0005] A Chinese invention patent with announcement number CN107934989ACN111088083A discloses a process for drying ammonium sulfate using desulfurization regeneration tail gas, in which a fan for the regeneration tail gas is used as the drying gas for ammonium sulfate.

[0006] The Chinese invention patent with announcement number CN115414768ACN111088083A discloses a device for combining desulfurization and regeneration tail gas with phosphate ammonium absorption and ammonia evaporation and a method of using the device, wherein the tail gas of a tower-type desulfurization and regeneration tower passes through an acid washing tank and an alkaline washing tower and is discharged into the atmosphere through a tail gas blower.

[0007] Announcement No. CN202221637350.5 discloses a treatment method for introducing desulfurization regeneration tail gas into a dry quenching coke oven for combustion. However, due to the high content of ammonia, H2S and other components in the tail gas, the untreated tail gas directly enters the dry quenching coke oven, which is easy to cause corrosion and blockage of pipelines and equipment. At the same time, the pipelines and equipment must use high-quality stainless steel, which is difficult to operate stably, increasing investment and operating costs.

[0008] Currently, the above existing solutions all have problems such as not being able to fully meet environmental protection requirements and not being able to operate stably for a long time. Summary of the invention

[0009] The purpose of the present invention is to provide an environmentally friendly and efficient oxidation desulfurization regeneration tail gas treatment system and method thereof, which overcomes the shortcomings of the prior art and adopts a multi-stage step-by-step washing system. The desulfurization regeneration tail gas is first subjected to alkali washing, acid washing and water washing in sequence, and the treated desulfurization regeneration tail gas is sent to a dry quenching coke oven for combustion treatment through a tail gas fan; a pressure measuring point is added after the tail gas fan, and when the dry quenching coke system cannot receive the desulfurization regeneration tail gas, resulting in overpressure in the tail gas pipeline, the switch valve is automatically interlocked with the pressure measuring point, and the tail gas enters the upper part of the water washing tower for release.

[0010] To achieve the above object, the present invention is implemented through the following technical solutions:

[0011] One of the technical solutions: an environmentally friendly and efficient oxidation desulfurization regeneration tail gas treatment system, characterized in that it is a multi-stage step-by-step washing system, including an alkali washing tower, an acid washing tower and a water washing tower, the regenerated tail gas inlet pipe is connected to the bottom of the alkali washing tower, the primary washing tail gas at the top of the alkali washing tower is connected to the bottom of the acid washing tower via a pipeline, the secondary washing tail gas at the top of the acid washing tower is connected to the bottom of the water washing tower via a pipeline, a vent pipe is provided at the top of the water washing tower, the bottom of the vent pipe is isolated from the inside of the water washing tower by a partition, a tertiary washing tail gas pipe is provided below the upper partition of the water washing tower, a tail gas fan is provided on the tertiary washing tail gas pipe, an overpressure return pipe is provided between the outlet of the tail gas fan and the vent pipe, a switch valve is provided on the overpressure return pipe, a pressure gauge is provided on the outlet pipeline of the tail gas fan, and the pressure gauge is interlocked with the switch valve for control.

[0012] A liquid cut-off plate is provided in the middle section of the alkali washing tower, a NaOH washing zone is located above the liquid cut-off plate, and a desulfurization lean liquid washing zone is located below the liquid cut-off plate; at least one group of spray pipes and fillers is provided in the NaOH washing zone and / or the desulfurization lean liquid washing zone.

[0013] The NaOH washing area is connected to an upper circulation pipe, an upper circulation pump is arranged on the upper circulation pipe, one end of the upper circulation pipe is connected to the NaOH washing area spray pipe, and the other end is connected to the liquid cut-off plate outlet.

[0014] The outlet side of the upper circulation pump is connected to the dilute alkali solution pipe, and the inlet side of the upper circulation pump is connected to the NaOH alkali solution pipe and the ammonia distillation waste water pipe.

[0015] At least one group of spray pipes and fillers is provided in the pickling tower, and multiple rows of nozzles are provided below the fillers. The nozzles and the spray pipes are connected to one end of a circulating acid pipe, and an acid pump is provided on the circulating acid pipe. The other end of the circulating acid pipe is connected to the bottom of the pickling tower; the inlet side of the acid pump is connected to the soft water supply pipe and the concentrated acid pipe, and the outlet side of the acid pump is connected to the circulating liquid pipe; the concentrated acid pipe is connected to the acid tank, and a metering pump is provided on the concentrated acid pipe.

[0016] The alkali washing tower is replaced by the alkali washing section in a conventional washing tower.

[0017] The acid wash tower is replaced by the acid wash section in a conventional wash tower.

[0018] The water washing tower is replaced by the water washing section of a conventional washing tower.

[0019] Technical solution two: An environmentally friendly and efficient oxidation desulfurization regeneration tail gas treatment method, through a multi-stage step-by-step washing system consisting of an alkali washing tower, an acid washing tower and a water washing tower, the regenerated tail gas is sequentially washed with desulfurization liquid, NaOH, acidic circulating liquid, and ammonia wastewater for sufficient washing, and then sent to a dry quenching furnace or a coke oven for combustion treatment through a tail gas fan; when the dry quenching furnace or coke oven system is unable to receive the desulfurization regeneration tail gas, resulting in overpressure in the tail gas pipeline, the switch valve on the overpressure return pipe between the outlet of the tail gas fan and the vent pipe is interlocked with a pressure gauge on the outlet pipeline of the tail gas fan. The switch valve is opened, and the tail gas returns to the vent pipe at the top of the water washing tower for discharge.

[0020] Concentrated sulfuric acid and soft water are added to the pickling tower. The concentrated sulfuric acid supply is quantitatively added by a metering pump and adjusted according to the ammonia content in the tail gas.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1) By setting a liquid cut-off plate in the alkali washing tower, the lower section is sprayed with desulfurization lean liquid to remove H2S and entrained sulfur powder in the tail gas, and the upper section is sprayed with NaOH alkali liquid sent from the ammonia distillation unit after being diluted with ammonia distillation wastewater to wash the tail gas, so as to achieve deep purification of the residual H2S component contained in the tail gas;

[0023] 2) The acid washing tower uses the acid circulating liquid sprayed in a cycle to contact the tail gas in reverse order to wash and absorb the ammonia in the tail gas. The acid tank and the concentrated sulfuric acid metering pump in the acid circulating liquid sprayed in a cycle are quantitatively replenished, which can be flexibly adjusted according to the ammonia content in the tail gas to improve the operation efficiency;

[0024] 3) The water washing tower uses the ammonia wastewater to contact the tail gas in reverse order to absorb the ammonium sulfate and acid mist carried in the tail gas. After alkali washing, acid washing and water washing, the harmful substances and corrosive components in the tail gas are greatly removed. The water washing tower and subsequent tail gas fans and external delivery pipelines can be made of carbon steel to reduce investment costs;

[0025] 4) The medium used in the whole system is the original process medium of the conventional process of coal gas purification, with low operating cost, easy to implement and promote. The desulfurization liquid used for washing is obtained from the lean liquid after the last stage of regeneration, and returns to the desulfurization rich liquid system after washing; the concentrated sulfuric acid comes from the ammonium sulfate unit or the oil depot unit, and the ammonium sulfate-rich liquid after washing returns to the ammonium sulfate unit; the concentrated alkali comes from the ammonia evaporation unit, and the diluted alkali after washing returns to the ammonia evaporation unit to decompose and fix ammonia for use; the water washing tower uses ammonia evaporation wastewater, which is sent to biochemical treatment after washing;

[0026] 5) Adding an exhaust fan to the system can not only overcome the resistance of the scrubber and pipeline, but also ensure the structural safety of the regeneration tower; a partition is set at the top of the scrubber to separate the chimney structure used for dissipation at the top of the scrubber from the tower body; a pressure measuring point is added after the exhaust fan, and a switch valve is automatically interlocked with the pressure measuring point. When the subsequent unit cannot receive the desulfurization regeneration exhaust gas, the exhaust gas is returned to the upper part of the scrubber for dissipation; the normal operation of the entire exhaust gas treatment system is ensured, while reducing air pollution, the dissipation height is guaranteed, the on-site environment is improved, and safe production is achieved;

[0027] 6) This process uses alkali washing, acid washing, water washing, and exhaust gas blower to send dry quenching or coke oven, which can not only meet the current environmental protection standards, but also recover ammonia in the exhaust gas without generating sewage discharge. It is environmentally friendly and efficient, the process is stable and reliable, and it is easy to implement and promote. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the process flow of an embodiment of the present invention.

[0029] In the figure: 1-alkaline washing tower, 2-acid washing tower, 3-water washing tower, 4-lower section circulating pump, 5-upper section circulating pump, 6-acid pump, 7-wastewater pump, 8-exhaust fan, 9-acid tank, 10-metering pump, 11-switch valve, 12-vent pipe, 13-pressure gauge, 14-overpressure return pipe, 15-liquid cut-off plate, 16-upper section circulating pipe, 17-circulating acid pipe. DETAILED DESCRIPTION

[0030] The technical solution of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments.

[0031] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the specific embodiments required to be used in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the specific embodiments described below are some implementation methods of the present invention. For ordinary technicians in this field, other specific embodiments can be obtained based on these specific embodiments without paying creative work.

[0032] The components of the embodiments of the present invention generally described and shown in the specific embodiments herein can be arranged and designed in countless different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the specific embodiments is not intended to limit the scope of the invention claimed, but merely represents selected embodiments of the present invention.

[0033] See Figure 1 , is a process flow diagram of an embodiment of an environmentally friendly and efficient oxidation desulfurization regeneration tail gas treatment system of the present invention, which is a multi-stage step-by-step washing system, including an alkali washing tower 1, an acid washing tower 2 and a water washing tower 3, the regeneration tail gas inlet pipe is connected to the bottom of the alkali washing tower 1, the primary washing tail gas at the top of the alkali washing tower 1 is connected to the bottom of the acid washing tower 2 through a pipeline, the secondary washing tail gas at the top of the acid washing tower 2 is connected to the bottom of the water washing tower 3 through a pipeline, a venting pipe 12 is provided at the top of the water washing tower 3, the bottom of the venting pipe 12 is isolated from the inside of the water washing tower 3 by a partition, the partition creatively enables the water washing tower to have the function of a chimney at the same time, a three-wash tail gas pipe is provided below the upper partition of the water washing tower 3, a tail gas fan 8 is provided on the three-wash tail gas pipe, an overpressure return pipe 14 is provided between the outlet of the tail gas fan 8 and the venting pipe 12, a switch valve 11 is provided on the overpressure return pipe 14, a pressure gauge 13 is provided on the outlet pipeline of the tail gas fan 8, and the pressure gauge 13 is interlocked with the switch valve 11 for control.

[0034] A liquid cut-off tray 15 is provided in the middle section of the alkali washing tower 1, above the liquid cut-off tray 15 is a NaOH washing area, and below the liquid cut-off tray 15 is a desulfurization lean liquid washing area; at least one group of spray pipes and packings are provided in the NaOH washing area and / or the desulfurization lean liquid washing area.

[0035] The NaOH washing area is connected to the upper circulation pipe 16, on which the upper circulation pipe 16 is provided with an upper circulation pump 5, one end of which is connected to the NaOH washing area spray pipe, and the other end is connected to the outlet of the liquid cut-off plate 15. The bottom of the desulfurization lean liquid washing area is connected to the desulfurization lean liquid pipe R2, on which the lower circulation pump 4 is provided.

[0036] The outlet side of the upper circulation pump 5 is connected to the dilute alkali solution pipe S2, and the inlet side of the upper circulation pump 5 is connected to the NaOH alkali solution pipe S1 and the ammonia evaporation waste water pipe W1.

[0037] At least one group of spray pipes and packings is provided in the pickling tower 2, and multiple rows of nozzles are provided under the packings. The nozzles and the spray pipes are connected to one end of a circulating acid liquid pipe 17, and an acid liquid pump 6 is provided on the circulating acid liquid pipe. The other end of the circulating acid liquid pipe 17 is connected to the bottom of the pickling tower 2; the inlet side of the acid liquid pump 6 is connected to the soft water supply pipe H1 and the concentrated acid pipe A1, and the outlet side of the acid liquid pump 6 is connected to the circulating liquid pipe A2; the concentrated acid pipe A1 is connected to the acid tank 9, and a metering pump 10 is provided on the concentrated acid pipe.

[0038] In the embodiment of the present invention, the alkali washing tower 1 can be replaced by the alkali washing section in a conventional washing tower. The acid washing tower 2 can be replaced by the acid washing section in a conventional washing tower. The water washing tower 3 can be replaced by the water washing section in a conventional washing tower, and the same effect can be achieved.

[0039] The invention discloses an environmentally friendly and efficient oxidation desulfurization regeneration tail gas treatment method, which is a multi-stage step-by-step washing system composed of an alkali washing tower 1, an acid washing tower 2 and a water washing tower 3, so that the regenerated tail gas is sequentially washed with desulfurization liquid, NaOH, acidic circulating liquid and ammonia waste water, and then sent to a dry quenching furnace or a coke oven for combustion treatment through a tail gas blower 8.

[0040] The present invention creatively adds a pressure measuring point after the exhaust fan and sets an overpressure return pipe 14. When the dry quenching furnace or coke oven system cannot receive the desulfurization regeneration exhaust gas, resulting in overpressure in the exhaust pipeline, the switch valve 11 on the overpressure return pipe 14 between the outlet of the exhaust fan 8 and the vent pipe 12 is interlocked with the pressure gauge 13 provided on the outlet pipeline F2 of the exhaust fan 8. The switch valve 11 is opened, and the exhaust gas returns to the vent pipe 12 at the top of the water washing tower 3 for discharge. This structure enables the operation of the entire exhaust gas treatment system to be unaffected by the dry quenching furnace or coke oven system, and the washing treatment of the regenerated exhaust gas can always be performed. The exhaust fan is continuously opened normally to ensure that the pressure in each washing tower is below the safe pressure. At the same time, it also avoids abnormal shutdown of the exhaust gas treatment system and adverse effects on other medium supply systems, providing an effective solution for the safe operation of the coke oven gas purification system.

[0041] The regenerated tail gas F1 from the regeneration tower enters the alkali washing tower 1. The alkali washing tower is provided with a liquid cut-off plate 15, which divides the alkali washing tower into two sections, the lower section, with the desulfurization lean liquid R1 sprayed and washed to remove H2S and entrained sulfur in the tail gas. The sprayed desulfurization liquid R2 is sent back to the desulfurization rich liquid pipeline through the lower section circulating pump 4 of the alkali washing tower. The upper section uses the NaOH alkali liquid S1 sent from the ammonia evaporation unit to dilute the ammonia evaporation wastewater W1, and then sprays and washes the tail gas through the upper section circulating pump 5 of the alkali washing tower to deeply purify the residual H2S components contained in the tail gas. The diluted alkali liquid S2 after washing is partially sent to the ammonia evaporation unit to decompose the fixed ammonia without being discharged.

[0042] The tail gas after alkali washing enters the acid washing tower 2, and the acid pump 6 is used to circulate and spray the acidic circulating liquid to contact the tail gas in reverse, washing and absorbing the ammonia in the tail gas. Soft water H1 is regularly added to the acid washing tower 2, and the concentrated acid A1 is temporarily stored in the acid tank 9, and is regularly quantitatively added by the metering pump 9 to maintain the acidity. The circulating liquid A2 after washing is partially sent to the ammonium sulfate unit. The tail gas after acid washing enters the water washing tower 3, and the ammonia wastewater W1 is used to contact the tail gas in reverse, absorbing the ammonium sulfate and acid mist entrained in the tail gas. The ammonia wastewater W2 after washing is directly sent to the biochemical treatment by the wastewater pump 7.

[0043] The scheme of the present invention can also be used to treat other tail gases in the gas purification process that are not suitable for entering the VOC system before being connected to the washing tower.

[0044] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An environmentally friendly and efficient oxidation desulfurization regeneration tail gas treatment system, characterized in that: It is a multi-stage step-by-step washing system, including an alkali washing tower, an acid washing tower and a water washing tower. The regenerated tail gas inlet pipe is connected to the bottom of the alkali washing tower, the primary washing tail gas at the top of the alkali washing tower is connected to the bottom of the acid washing tower through a pipeline, the secondary washing tail gas at the top of the acid washing tower is connected to the bottom of the water washing tower through a pipeline, a vent pipe is provided at the top of the water washing tower, the bottom of the vent pipe is isolated from the inside of the water washing tower by a partition, a tertiary washing tail gas pipe is provided below the upper partition of the water washing tower, a tail gas fan is provided on the tertiary washing tail gas pipe, an overpressure return pipe is provided between the outlet of the tail gas fan and the vent pipe, a switch valve is provided on the overpressure return pipe, a pressure gauge is provided on the outlet pipeline of the tail gas fan, and the pressure gauge is interlocked with the switch valve for control.

2. The environmentally friendly and efficient oxidation desulfurization regeneration tail gas treatment system according to claim 1 is characterized in that: A liquid cut-off plate is provided in the middle section of the alkali washing tower, a NaOH washing zone is located above the liquid cut-off plate, and a desulfurization lean liquid washing zone is located below the liquid cut-off plate; at least one group of spray pipes and fillers is provided in the NaOH washing zone and / or the desulfurization lean liquid washing zone.

3. An environmentally friendly and efficient oxidation desulfurization regeneration tail gas treatment system according to claim 2, characterized in that: The NaOH washing area is connected to an upper circulation pipe, an upper circulation pump is arranged on the upper circulation pipe, one end of the upper circulation pipe is connected to the NaOH washing area spray pipe, and the other end is connected to the liquid cut-off plate outlet.

4. The environmentally friendly and efficient oxidation desulfurization regeneration tail gas treatment system according to claim 3 is characterized in that: The outlet side of the upper circulation pump is connected to the dilute alkali solution pipe, and the inlet side of the upper circulation pump is connected to the NaOH alkali solution pipe and the ammonia distillation waste water pipe.

5. The environmentally friendly and efficient oxidation desulfurization regeneration tail gas treatment system according to claim 1 is characterized in that: At least one group of spray pipes and fillers is provided in the pickling tower, and multiple rows of nozzles are provided below the fillers. The nozzles and the spray pipes are connected to one end of a circulating acid pipe, and an acid pump is provided on the circulating acid pipe. The other end of the circulating acid pipe is connected to the bottom of the pickling tower; the inlet side of the acid pump is connected to the soft water supply pipe and the concentrated acid pipe, and the outlet side of the acid pump is connected to the circulating liquid pipe; the concentrated acid pipe is connected to the acid tank, and a metering pump is provided on the concentrated acid pipe.

6. The environmentally friendly and efficient oxidation desulfurization regeneration tail gas treatment system according to claim 1 is characterized in that: The alkali washing tower is replaced by the alkali washing section in a conventional washing tower.

7. The environmentally friendly and efficient oxidation desulfurization regeneration tail gas treatment system according to claim 1 is characterized in that: The acid wash tower is replaced by the acid wash section in a conventional wash tower.

8. The environmentally friendly and efficient oxidation desulfurization regeneration tail gas treatment system according to claim 1 is characterized in that: The water washing tower is replaced by the water washing section of a conventional washing tower.

9. An environmentally friendly and efficient oxidation desulfurization regeneration tail gas treatment method, characterized in that: Through a multi-stage step-by-step washing system consisting of an alkali washing tower, an acid washing tower and a water washing tower, the regenerated tail gas is washed thoroughly with desulfurization liquid, NaOH, acidic circulating liquid and ammonia wastewater in turn, and then sent to the dry quenching furnace or coke oven for combustion treatment through the tail gas fan; when the dry quenching furnace or coke oven system is unable to receive the desulfurization regenerated tail gas, resulting in overpressure in the tail gas pipeline, the switch valve on the overpressure return pipe between the outlet of the tail gas fan and the vent pipe is interlocked with a pressure gauge on the outlet pipeline of the tail gas fan. When the switch valve is opened, the tail gas returns to the vent pipe at the top of the water washing tower for discharge.

10. The environmentally friendly and efficient oxidation desulfurization regeneration tail gas treatment method according to claim 9, characterized in that: Concentrated sulfuric acid and soft water are added to the pickling tower. The concentrated sulfuric acid supply is quantitatively added by a metering pump and adjusted according to the ammonia content in the tail gas.

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