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

Abstract

The utility model 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, which 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, 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 device has the beneficial effects that the current environmental protection standard can be met, ammonia in tail gas can be recycled, no sewage is discharged, and the device has the characteristics of environmental protection, high efficiency, stable and reliable process and easiness in implementation and popularization.

Description

Technical Field

[0001] This utility model belongs to the field of coke oven gas purification technology, and in particular relates to an environmentally friendly and efficient oxidation method desulfurization and regeneration tail gas treatment system. Background Technology

[0002] Wet oxidation is a widely used desulfurization process for coke oven gas, offering advantages such as high desulfurization efficiency, low catalyst usage, low operating costs, and low initial investment. Its main principle involves circulating and spraying desulfurization liquid to absorb acidic components like H2S in the gas, then converting them into sulfur products for recovery in a regeneration tower or tank under the action of oxygen. The air used for regeneration not only has an oxidizing effect, but the precipitated sulfur adheres to the air bubbles, acting as a sulfur flotation foam. Because it comes into contact with ammonia-containing desulfurization liquid, the desulfurization regeneration tail gas contains a certain amount of ammonia and H2S, among other harmful substances. Direct emission of this gas would pollute the environment and cause serious harm; therefore, achieving the harmless treatment of desulfurization regeneration tail gas is of great significance.

[0003] Chinese utility model patent with announcement number CN111088083A discloses a system and process for reducing the emissions of desulfurization regeneration tail gas. The regeneration tail gas is pressurized and used as a gas source to enter the next stage of desulfurization regeneration tower, thereby reducing emissions by reusing the regeneration tail gas.

[0004] Chinese utility model patent with announcement number CN202010248989.3CN111088083A discloses a process for treating desulfurization regeneration tail gas using a tubular furnace, wherein the regeneration tail gas is sent into the tubular furnace by a blower for air distribution and reburning.

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

[0006] Chinese utility model patent with announcement number CN115414768ACN111088083A discloses a device for combining desulfurization regeneration tail gas with ammonium phosphate absorption and ammonia stripping, and its usage method. The tail gas of a single-tower desulfurization regeneration tower is passed through an acid washing tank and an alkaline washing tower, and then discharged into the atmosphere through a tail gas fan.

[0007] The announcement number CN202221637350.5 discloses a method for treating desulfurization regeneration tail gas by introducing it 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 entering the dry quenching coke oven can easily cause corrosion and blockage of pipelines and equipment. At the same time, the pipelines and equipment must be made of high-quality stainless steel, which makes it difficult to operate stably and increases investment and operating costs.

[0008] The existing solutions mentioned above all have problems such as not fully meeting environmental protection requirements and being unable to operate stably in the long term. Utility Model Content

[0009] The purpose of this invention is to provide an environmentally friendly and efficient desulfurization and regeneration tail gas treatment system using an oxidation method, overcoming the shortcomings of existing technologies. It employs a multi-stage step-by-step washing system, where the desulfurization and regeneration tail gas is sequentially subjected to alkaline washing, acid washing, and water washing. The treated tail gas is then sent to a dry quenching oven for combustion via a tail gas blower. A pressure measuring point is added after the tail gas blower. When the dry quenching system cannot receive the desulfurization and regeneration tail gas, causing overpressure in the tail gas pipeline, the switching valve and the pressure measuring point automatically interlock, and the tail gas is released into the upper part of the water washing tower.

[0010] To achieve the above objectives, this utility model provides the following technical solution:

[0011] An environmentally friendly and efficient oxidation-based desulfurization regeneration tail gas treatment system is disclosed. This system is a multi-stage, step-by-step scrubbing system, comprising an alkaline scrubbing tower, an acid scrubbing tower, and a water scrubbing tower. The regeneration tail gas inlet pipe is connected to the bottom of the alkaline scrubbing tower. The initial scrubbing tail gas from the top of the alkaline scrubbing tower is connected to the bottom of the acid scrubbing tower via a pipeline. The second scrubbing tail gas from the top of the acid scrubbing tower is connected to the bottom of the water scrubbing tower via a pipeline. A vent pipe is located at the top of the water scrubbing tower, and its bottom is isolated from the interior of the water scrubbing tower by a baffle plate. A third scrubbing tail gas pipe is located below the upper baffle plate of the water scrubbing tower. A tail gas fan is installed on the third scrubbing tail gas pipe. An overpressure return pipe is connected between the outlet of the tail gas fan and the vent pipe, and a switch valve is installed on the overpressure return pipe. A pressure gauge is installed on the outlet pipe of the tail gas fan, and the pressure gauge is interlocked with the switch valve.

[0012] The alkaline washing tower is equipped with a liquid cut-off plate in the middle section. Above the liquid cut-off plate is the NaOH washing zone, and below the liquid cut-off plate is the desulfurization lean liquor washing zone. The NaOH washing zone and / or the desulfurization lean liquor washing zone are equipped with at least one combination of spray pipes and packing.

[0013] The NaOH washing zone is connected to the upper circulation pipe, which is equipped with an upper circulation pump. One end of the upper circulation pipe is connected to the NaOH washing zone spray pipe, and the other end is connected to the outlet of the liquid cut-off plate.

[0014] The outlet side of the upper circulation pump is connected to a dilute alkali solution pipe, and the inlet side of the upper circulation pump is connected to a NaOH alkali solution pipe and an ammonia stripping wastewater pipe.

[0015] The pickling tower is equipped with at least one combination of spray pipes and packing. Multiple rows of nozzles are provided below the packing. Both the nozzles and spray pipes are connected to one end of the circulating acid pipe. 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 a soft water supply pipe and a concentrated acid pipe. The outlet side of the acid pump is connected to a circulating liquid pipe. The concentrated acid pipe is connected to the acid tank and is equipped with a metering pump.

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

[0017] The pickling tower is replaced by the pickling section of a conventional washing tower.

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

[0019] Compared with the prior art, the beneficial effects of this utility model are:

[0020] 1) By setting up a liquid cut-off plate in the alkaline washing tower, the lower section is sprayed with desulfurization lean liquid to remove H2S and entrained sulfur powder from the tail gas, and the upper section is sprayed with NaOH alkaline solution from the ammonia stripping unit after being diluted with ammonia stripping wastewater to wash the tail gas, thereby achieving deep purification of the residual H2S components contained in the tail gas.

[0021] 2) The acid washing tower uses the circulating acidic liquid sprayed in reverse contact with the tail gas to wash and absorb the ammonia in the tail gas. The acid tank and concentrated sulfuric acid metering pump in the circulating acidic liquid sprayed in the tower are quantitatively replenished, which can be flexibly adjusted according to the ammonia content in the tail gas to improve operating efficiency.

[0022] 3) The water washing tower utilizes the counter-current contact between the ammonia-steamed wastewater and the tail gas to absorb the ammonium sulfate and acid mist entrained in the tail gas. After alkaline washing, acid washing, and water washing, the harmful substances and corrosive components in the tail gas are greatly removed. The water washing tower and the subsequent tail gas fan and external pipeline can be made of carbon steel to reduce investment costs.

[0023] 4) The entire system uses the existing process media of conventional coal gas purification, which has low operating costs and is easy to implement and promote. The desulfurization liquid used for washing is obtained from the lean liquid after the last stage of regeneration and returned to the rich liquid system after washing. The concentrated sulfuric acid comes from the ammonium sulfate unit or the oil storage unit, and the ammonium sulfate-rich liquid after washing is returned to the ammonium sulfate unit. The concentrated alkali comes from the ammonia stripping unit, and the dilute alkali after washing is returned to the ammonia stripping unit for decomposition and fixation of ammonia. The water washing tower uses ammonia stripping wastewater, which is sent to biochemical treatment after washing.

[0024] 5) The addition of an exhaust gas fan to the system can overcome the resistance of the scrubbing tower and pipelines, while also ensuring the structural safety of the regeneration tower; a baffle is installed at the top of the water scrubbing tower to separate the original chimney structure used for venting from the tower body; a pressure measuring point is added after the exhaust gas fan, and an automatic interlock is set between the switch valve and the pressure measuring point. When the downstream unit cannot receive the desulfurization regeneration exhaust gas, the exhaust gas is returned to the top of the water scrubbing tower for venting; this ensures the normal operation of the entire exhaust gas treatment system, reduces air pollution, ensures the venting height, improves the on-site environment, and achieves safe production.

[0025] 6) This process uses alkaline washing, acid washing, water washing, and exhaust gas blower to dry quenching coke or coke oven. It can meet the current environmental protection standards, recover ammonia in the exhaust gas, and does not generate wastewater discharge. It has the characteristics of being environmentally friendly and efficient, stable and reliable, easy to implement and promote. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the process flow of an embodiment of this utility model.

[0027] In the diagram: 1-Alkali washing tower, 2-Acid washing tower, 3-Water washing tower, 4-Lower circulation pump, 5-Upper circulation pump, 6-Acid pump, 7-Wastewater pump, 8-Tail gas 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 circulation pipe, 17-Circulating acid pipe. Detailed Implementation

[0028] The technical solution of this utility model will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are some embodiments of this utility model, but not all embodiments.

[0029] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the specific embodiments used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the specific embodiments described below are some embodiments of this utility model. For those skilled in the art, other specific embodiments can be obtained based on these specific embodiments without creative effort.

[0030] The components of the present invention described and shown in the specific embodiments herein can be arranged and designed in numerous 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 claimed invention, but merely to illustrate selected embodiments of the invention.

[0031] See Figure 1This is a schematic diagram of the process flow of an embodiment of an environmentally friendly and efficient oxidation-based desulfurization regeneration tail gas treatment system of this utility model. It is a multi-stage step-by-step washing system, including an alkaline 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 alkaline washing tower 1. The initial washing tail gas at the top of the alkaline washing tower 1 is connected to the bottom of the acid washing tower 2 via 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 via a pipeline. The top of the water washing tower 3 is equipped with a vent pipe 12. The bottom of the vent pipe 12 is isolated from the interior of the water washing tower 3 by a baffle plate. The baffle plate creatively enables the water washing tower to also function as a chimney. Below the upper baffle plate of the water washing tower 3, there is a third washing tail gas pipe. A tail gas fan 8 is installed on the third washing tail gas pipe. An overpressure return pipe 14 is installed between the outlet of the tail gas fan 8 and the vent pipe 12. A switch valve 11 is installed on the overpressure return pipe 14. A pressure gauge 13 is installed on the outlet pipe of the tail gas fan 8. The pressure gauge 13 is interlocked with the switch valve 11.

[0032] The middle section of the alkaline washing tower 1 is equipped with a liquid cut-off plate 15. Above the liquid cut-off plate 15 is the NaOH washing zone, and below the liquid cut-off plate 15 is the desulfurization lean liquor washing zone. The NaOH washing zone and / or the desulfurization lean liquor washing zone are equipped with at least one combination of spray pipes and packing.

[0033] The NaOH washing zone is connected to the upper circulation pipe 16, which is equipped with an upper circulation pump 5. One end of the upper circulation pipe 16 is connected to the spray pipe of the NaOH washing zone, and the other end is connected to the outlet of the liquid cut-off plate 15. The bottom of the desulfurization lean liquor washing zone is connected to the desulfurization lean liquor pipe R2, which is equipped with a lower circulation pump 4.

[0034] 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 stripping wastewater pipe W1.

[0035] The pickling tower 2 is equipped with at least one combination of spray pipes and packing. Multiple rows of nozzles are provided below the packing. Both the nozzles and spray pipes are connected to one end of the circulating acid pipe 17. The circulating acid pipe is equipped with an acid pump 6. The other end of the circulating acid pipe 17 is connected to the bottom of the pickling tower 2. The inlet side of the acid pump 6 is connected to the soft water supply pipe H1 and the concentrated acid pipe A1. The outlet side of the acid pump 6 is connected to the circulating liquid pipe A2. The concentrated acid pipe A1 is connected to the acid tank 9. The concentrated acid pipe is equipped with a metering pump 10.

[0036] In this embodiment of the invention, the alkaline washing tower 1 can be replaced by the alkaline washing section of a conventional washing tower. The acid washing tower 2 can be replaced by the acid washing section of a conventional washing tower. The water washing tower 3 can be replaced by the water washing section of a conventional washing tower, all of which can achieve the same function.

[0037] This utility model discloses an environmentally friendly and efficient oxidation method for treating desulfurization regeneration tail gas. The method involves a multi-stage stepwise washing system consisting of an alkaline washing tower 1, an acid washing tower 2, and a water washing tower 3. The regeneration tail gas is then thoroughly washed by passing through desulfurization liquid, NaOH, acidic circulating liquid, and ammonia stripping wastewater in sequence before being sent to a dry quenching furnace or coke oven for combustion treatment via a tail gas blower 8.

[0038] This invention creatively adds a pressure measuring point and an overpressure return pipe 14 after the exhaust gas fan. When the dry quenching furnace or coke oven system cannot receive the desulfurization regeneration exhaust gas, causing overpressure in the exhaust gas pipeline, the switch valve 11 on the overpressure return pipe 14 between the outlet of the exhaust gas fan 8 and the vent pipe 12 is interlocked with the pressure gauge 13 on the outlet pipeline F2 of the exhaust gas fan 8. When the switch valve 11 opens, the exhaust gas returns to the vent pipe 12 at the top of the water washing tower 3 for venting. This structure ensures that the operation of the entire exhaust gas treatment system is unaffected by the dry quenching furnace or coke oven system, allowing for continuous washing of the regeneration exhaust gas. The exhaust gas fan continues to operate normally, ensuring that the pressure in each washing tower remains below safe levels. It also avoids the adverse effects of abnormal shutdowns of the exhaust gas treatment system on other media supply systems, providing an effective solution for the safe operation of the coke oven gas purification system.

[0039] The regeneration tail gas F1 from the regeneration tower enters the alkaline scrubbing tower 1. The alkaline scrubbing tower is equipped with a liquid cut-off plate 15, dividing it into upper and lower sections. The lower section is sprayed with desulfurization lean solution R1 to remove H2S and entrained sulfur from the tail gas. The sprayed desulfurization solution R2 is then returned to the desulfurization rich solution pipeline via the lower section circulation pump 4. The upper section uses NaOH alkaline solution S1 from the ammonia stripping unit, diluted with ammonia stripping wastewater W1, and then sprayed onto the tail gas via the upper section circulation pump 5 to deeply purify the residual H2S components in the tail gas. A portion of the washed dilute alkaline solution S2 is sent to the ammonia stripping unit for decomposition and fixation of ammonia, preventing its discharge.

[0040] The tail gas after alkaline washing enters acid washing tower 2, where acidic circulating liquid is sprayed by acid pump 6 to come into counter-current contact with the tail gas, washing and absorbing ammonia in the tail gas. Soft water H1 is periodically added to acid washing tower 2, and concentrated acid A1 is temporarily stored in acid tank 9 and periodically replenished by metering pump 9 to maintain acidity. Part of the circulating liquid A2 after washing is sent to the ammonium sulfate unit. The tail gas after acid washing enters water washing tower 3, where ammonia stripping wastewater W1 comes into counter-current contact with the tail gas to absorb ammonium sulfate and acid mist entrained in the tail gas. The ammonia stripping wastewater W2 after washing is directly sent to biochemical treatment by wastewater pump 7.

[0041] This invention also allows for the treatment of other exhaust gases that are not suitable for entering the VOC system during coal gas purification, by connecting them to the scrubbing tower for combined treatment.

[0042] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An environmentally friendly and efficient oxidation-based desulfurization and regeneration tail gas treatment system, characterized in that, It is a multi-stage step-by-step washing system, including an alkaline washing tower, an acid washing tower, and a water washing tower. The regeneration tail gas inlet pipe is connected to the bottom of the alkaline washing tower. The initial washing tail gas at the top of the alkaline washing tower is connected to the bottom of the acid washing tower via a pipeline. The second washing tail gas at the top of the acid washing tower is connected to the bottom of the water washing tower via a pipeline. The top of the water washing tower is equipped with a vent pipe. The bottom of the vent pipe is isolated from the interior of the water washing tower by a baffle. A third washing tail gas pipe is located below the baffle at the top of the water washing tower. A tail gas fan is installed on the third washing tail gas pipe. An overpressure return pipe is installed between the outlet of the tail gas fan and the vent pipe. A switch valve is installed on the overpressure return pipe. A pressure gauge is installed on the outlet pipe of the tail gas fan. The pressure gauge is interlocked with the switch valve for control.

2. The environmentally friendly and efficient oxidation-based desulfurization and regeneration tail gas treatment system according to claim 1, characterized in that, The alkaline washing tower is equipped with a liquid cut-off plate in the middle section. Above the liquid cut-off plate is the NaOH washing zone, and below the liquid cut-off plate is the desulfurization lean liquor washing zone. The NaOH washing zone and / or the desulfurization lean liquor washing zone are equipped with at least one combination of spray pipes and packing.

3. The environmentally friendly and efficient oxidation-based desulfurization and regeneration tail gas treatment system according to claim 2, characterized in that, The NaOH washing zone is connected to the upper circulation pipe, which is equipped with an upper circulation pump. One end of the upper circulation pipe is connected to the NaOH washing zone spray pipe, and the other end is connected to the outlet of the liquid cut-off plate.

4. The environmentally friendly and efficient oxidation-based desulfurization and regeneration tail gas treatment system according to claim 3, characterized in that, The outlet side of the upper circulation pump is connected to a dilute alkali solution pipe, and the inlet side of the upper circulation pump is connected to a NaOH alkali solution pipe and an ammonia stripping wastewater pipe.

5. The environmentally friendly and efficient oxidation-based desulfurization and regeneration tail gas treatment system according to claim 1, characterized in that, The pickling tower is equipped with at least one combination of spray pipes and packing. Multiple rows of nozzles are provided below the packing. Both the nozzles and spray pipes are connected to one end of the circulating acid pipe. 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 a soft water supply pipe and a concentrated acid pipe. The outlet side of the acid pump is connected to a circulating liquid pipe. The concentrated acid pipe is connected to the acid tank and is equipped with a metering pump.

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

7. The environmentally friendly and efficient oxidation-based desulfurization and regeneration tail gas treatment system according to claim 1, characterized in that, The pickling tower is replaced by the pickling section of a conventional washing tower.

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

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