High concentration batch organic exhaust pretreatment system and method

Abstract

The present application relates to the technical field of industrial waste gas treatment, and provides a high-concentration intermittent organic exhaust gas pretreatment system and method. The system comprises an absorption tower, a lean liquid tank, a rich liquid tank, a spraying tower and the like. The absorption tower is connected with a system air inlet main pipe, and the spraying tower is connected with a spraying fan. Tail gas main pipes of the absorption tower and the spraying tower are respectively connected with a post-treatment combustion device. The absorption tower is connected with the lean liquid tank through a lean liquid supplement pipeline, and the lean liquid tank is connected with the spraying tower through a lean liquid extraction pipeline. The absorption tower is connected with the rich liquid tank through a rich liquid extraction pipeline, and the rich liquid tank is connected with the spraying tower through a rich liquid supplement pipeline. When the tail gas concentration of the absorption tower is low, the amount of lean liquid supplement or rich liquid extraction of the absorption tower is reduced, or the spraying system is started. When the tail gas concentration of the spraying tower is low, the amount of lean liquid extraction of the spraying tower is reduced, or the spraying air volume is increased. The system can stably maintain the organic exhaust gas concentration entering the post-treatment combustion device under intermittent and fluctuating working conditions.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of tank exhaust and process exhaust treatment in petrochemical, fine chemical and other industries, and particularly relates to a high-concentration intermittent organic exhaust pretreatment system. BACKGROUND

[0002] The petrochemical, fine chemical and other industries often involve high-concentration intermittent organic exhaust, which usually has the characteristics of large flow and concentration fluctuation and high saturated vapor pressure. Due to the increasingly stringent emission limits of non-methane total hydrocarbons and characteristic pollutants in existing atmospheric pollution comprehensive emission standards and atmospheric pollutant industry emission standards, combustion method is usually used as the end and deep treatment method for waste gas treatment, but the waste gas combustion process related design specifications (such as “Technical Code for Industrial Organic Waste Gas Treatment by Regenerative Combustion Method” (HJ1093-2020) and “Technical Code for Industrial Organic Waste Gas Treatment by Catalytic Combustion Method” HJ2027-2013) require that the pollutant inlet concentration should not exceed 25% of the lower explosive limit, so pretreatment measures must be taken to reduce the pollutant concentration in the waste gas. Traditional pretreatment methods include condensation, absorption and adsorption, which can reduce the concentration of high-concentration organic exhaust.

[0003] However, under intermittent exhaust conditions, when the exhaust flow or organic matter concentration is low, it cannot meet the requirement of maintaining sufficient combustion state of the post-treatment combustion equipment. Since the combustion equipment often needs to be continuously operated after starting, it cannot be started and stopped at will, and when the exhaust volume is small or the organic matter concentration is low, the post-treatment waste gas combustion equipment is in an empty burning state, the consumption of supplemental fuel is extremely large, and the operation cost of the equipment causes great pressure on the user. The technical means of gas cabinet and other pre-storage of organic exhaust has the defects of high risk, high operation and management requirement, large occupation area and high investment, and has low operability in actual application. SUMMARY

[0004] The present application provides a high-concentration intermittent organic exhaust pretreatment system and method to solve the problem of large consumption of supplemental fuel caused by fluctuations in organic matter concentration and exhaust flow in the prior art. The present pretreatment system can effectively regulate the stability of the exhaust entering the post-treatment combustion equipment.

[0005] In the first aspect of the present application, a high-concentration intermittent organic exhaust gas pretreatment system is provided, which comprises an absorption tower, a lean liquid tank, a rich liquid tank and a spray tower; the absorption tower is connected with a system inlet gas main pipe, and the spray tower is connected with a spray fan; tail gas mains of the absorption tower and the spray tower are respectively connected with a post-treatment combustion device; the absorption tower has an absorption liquid in a tower kettle; the absorption tower is connected with the lean liquid tank through a lean liquid supplement pipeline, and the lean liquid tank is connected with the spray tower through a lean liquid extraction pipeline; the absorption tower is connected with the rich liquid tank through a rich liquid extraction pipeline, and the rich liquid tank is connected with the spray tower through a rich liquid supplement pipeline; a first gas concentration detector is arranged on the tail gas main of the absorption tower, and the first gas concentration detector is interlocked with automatic regulating valves arranged on the lean liquid supplement pipeline and the rich liquid extraction pipeline; a second gas concentration detector is arranged on a tail gas pipe of the spray tower, and the second gas concentration detector is interlocked with the spray fan and the automatic regulating valves arranged on the lean liquid extraction pipeline.

[0006] Optionally, the tower kettle of the absorption tower is connected with a spraying port of a tower body through an absorption liquid circulating pump and an absorption liquid circulating pipeline; the absorption liquid circulating pipeline is connected with the rich liquid tank through the rich liquid extraction pipeline; the tower kettle of the spray tower is connected with a spraying port of a tower body through a spray liquid circulating pump and a spray liquid circulating pipeline; and the spray liquid circulating pipeline is connected with the lean liquid tank through the lean liquid extraction pipeline.

[0007] Optionally, a rich liquid heater is arranged, an inlet of the rich liquid heater is connected with the spray liquid circulating pipeline, and an outlet of the rich liquid heater is connected with the spraying port of the tower body of the spray tower; and a heat regulating device of the rich liquid heater is interlocked with the second gas concentration detector.

[0008] Optionally, the rich liquid heater is a tube-shell heat exchanger, a hot fluid of the heat exchanger can be low-pressure steam or hot flue gas, the spray liquid in the rich liquid heater passes through a tube pass, and the hot fluid passes through a shell pass; an automatic regulating valve of an inlet pipeline or an outlet pipeline of the hot fluid is interlocked with the second gas concentration detector.

[0009] Optionally, a pressure transmitter and an automatic switch valve are arranged on the system inlet gas main pipe in sequence according to an inlet gas direction, and the pressure transmitter and the automatic switch valve are connected with an inlet of the absorption tower through an induced draft fan; the pressure transmitter, the automatic switch valve and a motor of the induced draft fan are interlocked.

[0010] Optionally, the lean liquid tank and the rich liquid tank are respectively connected with a fresh absorption liquid main pipe and a sewage main pipe, and the lean liquid tank and the rich liquid tank are respectively provided with liquid level control devices for adjusting inlet liquid and outlet liquid of the lean liquid tank and the rich liquid tank.

[0011] Optionally, the absorption liquid is process water or an organic solvent.

[0012] In a second aspect of the present application, a high-concentration intermittent organic exhaust gas pretreatment method is provided, which is based on the high-concentration intermittent organic exhaust gas pretreatment system described above; when the tail gas concentration of the absorption tower is lower than a first set value, the opening degree of the automatic regulating valve on the lean liquid supplement pipeline or the rich liquid extraction pipeline is reduced; if the tail gas concentration of the absorption tower is still lower than the first set value, the spray tower is started to spray; when the tail gas concentration of the spray tower is lower than a second set value, the opening degree of the automatic regulating valve on the lean liquid extraction pipeline or the flow of the spray blower is reduced.

[0013] Optionally, when the tail gas concentration of the absorption tower is higher than the first set value, the opening degree of the automatic regulating valve on the lean liquid supplement pipeline or the rich liquid extraction pipeline is increased; when the tail gas concentration of the spray tower is higher than the second set value, the opening degree of the automatic regulating valve on the lean liquid extraction pipeline or the flow of the spray blower is increased.

[0014] Optionally, the spray tower is connected with a rich liquid heater for heating the spray liquid; when the tail gas concentration of the spray tower is higher or lower than the second set value, the heating power of the rich liquid heater is correspondingly reduced or increased.

[0015] As can be seen from the above scheme, the pretreatment system of the present application reduces the concentration of high-concentration organic exhaust gas to a target concentration through the absorption system, and the tail gas of the absorption tower is deeply treated in the waste gas combustion equipment to meet the emission standard; the rich liquid enriched with pollutants in the exhaust gas generated in the absorption process is stored in the rich liquid tank. Due to the intermittent production condition, when no exhaust gas is generated or the exhaust gas amount is low, the rich liquid in the rich liquid tank is pumped into the spray tower, the pollutants in the rich liquid are sprayed out by the spray blower, the tail gas of the spray tower is deeply treated in the waste gas combustion equipment to meet the emission standard, and the rich liquid is purified as lean liquid and discharged into the lean liquid tank for temporary storage as the absorption liquid of the absorption tower.

[0016] Compared with the traditional high-concentration intermittent organic exhaust gas pretreatment process, the pretreatment system of the present application not only can reduce the concentration of high-concentration organic exhaust gas to realize stable control of the pollutant concentration entering the post-treatment combustion equipment, but also can temporarily store part of the organic pollutants in the intake gas in the absorption liquid, transfer the pollutants in the absorption liquid to the gas when no exhaust gas is generated or the exhaust gas amount is low, make the amount of pollutants entering the post-treatment combustion equipment continuous and stable, and control the amount of pollutants in the pretreatment tail gas in a relatively economical range through automatic control means, thereby reducing the consumption of supplemental fuel and further reducing the operation cost of the deep treatment equipment. In addition, the pretreatment system has the advantages of high automation degree and simple operation and maintenance. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 FIG. 1 is a structural schematic diagram of the storage tank exhaust gas pretreatment system of the present application.

[0018] In the figure, 1 - system intake main pipe, 2 - air blower, 3 - absorption tower intake pipe, 4 - absorption tower, 5 - absorption liquid circulating pump, 6 - absorption liquid circulating pipeline, 7 - lean liquid supplement pipeline, 8 - first fresh absorption liquid supplement pipeline, 9 - absorption tower tail gas main pipe, 10 - rich liquid extraction pipeline, 11 - lean liquid tank, 12 - lean liquid pump, 13 - lean liquid tank blowdown pipe, 14 - air filter, 15 - injection blower, 16 - injection tower intake pipe, 17 - injection tower, 18 - injection liquid circulating pipeline, 19 - injection liquid circulating pump, 20 - rich liquid supplement pipeline, 21 - second fresh absorption liquid supplement pipeline, 22 - injection tower tail gas pipe, 23 - lean liquid extraction pipeline, 24 - rich liquid heater, 25 - rich liquid tank, 26 - rich liquid pump, 27 - rich liquid tank blowdown pipe, 28 - hot fluid outlet pipeline, 29 - hot fluid inlet pipeline, 30 - fresh absorption liquid main pipe, 31 - sewage main pipe, 41 - first gas concentration detector, 42 - second gas concentration detector. DETAILED DESCRIPTION

[0019] The preferred technical solutions of the present application will be described in detail below in combination with the drawings and specific embodiments.

[0020] As shown in the figure, the high-concentration intermittent organic exhaust gas pretreatment system provided by the present application comprises an absorption tower 4, a lean liquid tank 11, a rich liquid tank 25 and an injection tower 17; the absorption tower 4 is connected with the system intake main pipe 1, and the injection tower 17 is connected with an injection blower 15; the tail gas main pipes of the absorption tower 4 and the injection tower 17 are respectively connected with a post-treatment combustion device. Figure 1 The absorption tower 4 is connected with the lean liquid tank 11 through the lean liquid supplement pipeline 7, the lean liquid tank 11 is connected with the injection tower 17 through the lean liquid extraction pipeline 23, the absorption tower 4 is connected with the rich liquid tank 25 through the rich liquid extraction pipeline 10, and the rich liquid tank 25 is connected with the injection tower 17 through the rich liquid supplement pipeline 20.

[0021] Specifically, the absorption liquid in the tower kettle of the absorption tower 4 absorbs the organic pollutants in the high-concentration organic exhaust gas of the system, and is rich liquid, which is extracted into the rich liquid tank 25 through the rich liquid extraction pipeline 10. The rich liquid in the rich liquid tank 25 enters the tower kettle of the injection tower 17 as injection liquid. The injection liquid is injected in the injection tower 17, and based on the stripping principle, the volatile organic compounds VOCs and other pollutants are continuously transferred from the liquid phase to the gas phase by the injection blower. The injection tail gas enters the post-treatment combustion device. After the organic matter in the injection liquid is injected, the organic matter is less, and then the injection liquid is extracted from the tower kettle of the injection tower 17 into the lean liquid tank 11 through the lean liquid extraction pipeline 23 as lean liquid. The lean liquid in the lean liquid tank 11 enters the tower kettle of the absorption tower as absorption liquid.

[0022]

[0023] ​A first gas concentration detector 41 is arranged on the tail gas main pipe 9 of the absorption tower, and is interlocked with the automatic regulating valve arranged on the lean liquid supplement pipeline 7 and the rich liquid extraction pipeline 10. A second gas concentration detector 42 is arranged on the tail gas pipe 22 of the spray tower, and is interlocked with the automatic regulating valve arranged on the lean liquid extraction pipeline 23 and the motor of the spray blower 15. The motor of the spray blower 15 is a variable frequency motor.

[0024] Specifically, in order to realize stable control of the gas concentration entering the post-processing combustion equipment, a gas concentration detector is arranged on the tail gas pipe of the absorption tower, and is interlocked with the automatic regulating valve arranged on the lean liquid supplement pipeline 7 and the rich liquid extraction pipeline 10. A gas concentration detector is arranged on the tail gas pipe of the spray tower, and is interlocked with the motor of the spray blower 15 and the automatic regulating valve arranged on the lean liquid extraction pipeline 23. The above-mentioned automatic control measures are the key measures for controlling the gas concentration entering the post-processing combustion equipment.

[0025] Automatic control and regulation method:

[0026] When the tail gas concentration of the absorption tower 4 is lower than the first set value, the opening degree of the automatic regulating valve on the lean liquid supplement pipeline 7 or the rich liquid extraction pipeline 10 is reduced. If the tail gas concentration of the absorption tower 4 is still lower than the first set value, the spray tower 17 is started to spray. When the tail gas concentration of the spray tower 17 is lower than the second set value, the opening degree of the automatic regulating valve on the lean liquid extraction pipeline 23 or the flow of the spray blower 15 is reduced.

[0027] When the tail gas concentration of the absorption tower 4 is higher than the first set value, the opening degree of the automatic regulating valve on the lean liquid supplement pipeline 7 or the rich liquid extraction pipeline 10 is increased. When the tail gas concentration of the spray tower 17 is higher than the second set value, the opening degree of the automatic regulating valve on the lean liquid extraction pipeline 23 or the flow of the spray blower 15 is increased.

[0028] The above scheme can be seen that:

[0029] The present application provides a high concentration intermittent organic exhaust gas pretreatment system, which is suitable for treating organic exhaust gas with large flow and concentration fluctuation and high saturated vapor pressure. The treatment system reduces the concentration of high concentration organic exhaust gas to a target concentration through an absorption system, and the tail gas of the absorption tower is treated in a waste gas combustion equipment to meet the emission standard. The rich liquid containing pollutants in the exhaust gas generated in the absorption process is stored in a rich liquid tank. When no exhaust gas is generated or the exhaust gas amount is low due to intermittent production conditions, the rich liquid in the rich liquid tank is pumped into a spray tower, and the pollutants in the rich liquid are sprayed out by a spray blower. The tail gas of the spray tower enters the waste gas combustion equipment, and the organic pollutants in the tail gas are used as fuel of the combustion equipment. The tail gas is treated to meet the emission standard, and the rich liquid is purified as lean liquid and discharged into a lean liquid tank for storage, which is used as the absorption liquid of the absorption tower.

[0030] As preferred, the system air intake main pipe 1 is provided with a pressure transmitter and an automatic switch valve in sequence in the air intake direction, and is connected with the air intake port of the absorption tower 4 through the induced draft fan 2; the pressure transmitter is interlocked with the automatic switch valve and the switch of the induced draft fan 2.

[0031] Specifically, when the storage tank exhaust or process exhaust is generated, the pressure transmitter provided on the system air intake main pipe 1 detects the value rising, and the automatic switch valve and the induced draft fan 2 after the interlocking opening of the pressure transmitter are opened, and the exhaust is introduced into the absorption tower 4 through the absorption tower air intake pipe 3. In some embodiments, when the exhaust entering the system air intake main pipe 1 has its own pressure, the induced draft fan 2 can not be configured, such as the exhaust pressure of ethylene oxide and propylene oxide storage tank, which is usually above 0.1 MPaG, and the induced draft fan 2 is not needed for this working condition.

[0032] As preferred, in the pipeline design, the rich liquid extraction pipeline 10 and the lean liquid extraction pipeline 23 are respectively used as bypasses on the absorption tower and the spray tower circulation pipeline, and the connection between the tower and the tank is realized by means of the circulation pump. Specifically: the tower kettle of the absorption tower 4 is connected with the spray port of the tower body through the absorption liquid circulation pump 5 and the absorption liquid circulation pipeline 6; the absorption liquid circulation pipeline 6 is connected with the rich liquid tank 25 through the rich liquid extraction pipeline 10; the tower kettle of the spray tower 17 is connected with the spray port of the tower body through the spray liquid circulation pump 19 and the spray liquid circulation pipeline 18; the spray liquid circulation pipeline 18 is connected with the lean liquid tank 11 through the lean liquid extraction pipeline 23. Preferably, the spray liquid circulation pipeline 18 is provided with a temperature transmitter.

[0033] As preferred, the spray liquid circulation pipeline of the spray tower 17 is also connected with the rich liquid heater 24, wherein the spray liquid flows into the spray port of the tower body after being heated by the rich liquid heater 24, so as to achieve faster and more efficient gas stripping. The inlet of the rich liquid heater 24 is connected with the spray liquid circulation pipeline 18, and the outlet is connected with the spray port of the tower body of the spray tower, and the heat regulating device of the rich liquid heater is interlocked with the second gas concentration detector.

[0034] As preferred, the rich liquid heater 24 is a tubular heat exchanger, and the hot fluid can be low-pressure steam or hot flue gas, and the spray liquid in the rich liquid heater passes through the tube, and the hot fluid passes through the shell; the automatic regulating valve on the hot fluid inlet pipeline 29 or the hot fluid outlet pipeline 28 is interlocked with the second gas concentration detector 42.

[0035] Specifically, the automatic regulating valve on the hot fluid inlet pipeline 29 or the hot fluid outlet pipeline 28 is used as the heat regulating device of the rich liquid heater, and the flow rate and other parameters of the hot fluid or cold fluid are adjusted through pipeline opening degree control and other adjusting modes, so as to realize the adjustment of the heating power of the rich liquid heater.

[0036] As preferred, the absorption liquid is process water or an organic solvent.

[0037] Specifically, the absorption liquid is selected according to the organic matter properties and economy, for example, for the organic exhaust with good water solubility, the absorption liquid can be process water; for the organic exhaust with poor water solubility, the absorption liquid can be an organic solvent with low saturated vapor pressure, such as ethylene glycol.

[0038] As preferred, the absorption tower 4 is of the bottom-in top-out type, and the absorption liquid is of the top-in bottom-out type, the flow direction of the exhaust gas in the tower is opposite to that of the absorption liquid, so that the gas-liquid phases are fully contacted, and the organic matter in the exhaust gas is fully absorbed into the liquid phase; a demisting layer is arranged at the top of the tower, a liquid level transmitter, an overflow port and a blow-off port are arranged at the tower bottom, and the overflow port and the blow-off port are connected with the sewage main. Similarly, the injection tower 17 is of the bottom-in top-out type, and the injection liquid is of the top-in bottom-out type, the flow direction of the injection gas in the tower is opposite to that of the injection liquid, so that the gas-liquid phases are fully contacted, and the organic matter in the injection liquid is fully injected into the gas phase; a demisting layer is arranged at the top of the tower, a liquid level transmitter, an overflow port and a blow-off port are arranged at the tower bottom, and the overflow port and the blow-off port are connected with the sewage main.

[0039] As preferred, the motors of the induced draft fan and the injection fan are variable frequency and explosion-proof.

[0040] As preferred, the induced draft fan is a zero-leakage fan, and is of a mechanical seal type; the induced draft fan is preferably a centrifugal fan or a Roots fan.

[0041] As preferred, the injection fan is preferably a centrifugal fan or a Roots fan.

[0042] As preferred, the gas concentration detector is preferably of FID or FTA.

[0043] The following provides a specific embodiment in combination with the device structure, process flow and self-control adjustment method of the pretreatment system of the present application:

[0044] When the exhaust gas from the storage tank or the process exhaust gas is generated, the pressure transmitter arranged on the system gas inlet main pipe 1 detects that the value increases, and the automatic switch valve and the induced draft fan 2 after the pressure transmitter are opened in interlock, and the exhaust gas is introduced into the absorption tower 4 through the absorption tower gas inlet pipe 3.

[0045] The absorption tower 4 is provided with an absorption liquid circulating pump 5 and a lean liquid tank 11, the outlet of the absorption liquid circulating pump 5 is connected with the spray port of the absorption tower 4 through an absorption liquid circulating pipeline 6, the absorption liquid circulating pipeline 6 is provided with a bypass, i.e. a rich liquid outlet pipeline 10. The lean liquid tank 11 is provided with a lean liquid pump 12, which is used to add fresh absorption liquid to the absorption tower 4, and the outlet of the lean liquid pump 12 is connected with the liquid supplement port of the absorption tower 4 through a lean liquid supplement pipeline 7. After the high-concentration organic exhaust gas is reduced in concentration by the absorption tower 4, the tail gas is discharged into the aftertreatment combustion equipment for deep treatment through an absorption tower tail gas main pipe 9. The absorption tower tail gas main pipe 9 is provided with a first gas concentration detector 41, which is interlocked with the automatic adjustment valves arranged on the lean liquid supplement pipeline 7 and the rich liquid outlet pipeline 10.

[0046] Control method: When the first gas concentration detector is lower than the set value, the opening of the automatic regulating valve on the lean liquid supplement pipeline 7 or the opening of the automatic regulating valve on the rich liquid production pipeline 10 can be reduced in a gradient control manner. When the first gas concentration detector is higher than the set value, the opening of the automatic regulating valve on the lean liquid supplement pipeline 7 or the opening of the automatic regulating valve on the rich liquid production pipeline 10 can be increased in a gradient control manner.

[0047] When the first gas concentration detector of the absorption tower tail gas main pipe 9 is still lower than the set value after the above control measures are taken, the injection system can be started to increase the gas concentration entering the post-processing combustion equipment.

[0048] The injection tower 17 is equipped with an injection liquid circulating pump 19, an injection blower 15, a rich liquid heater 24, a rich liquid tank 25, etc. The injection blower 15 inlet is equipped with an air filter 14, and the outlet is connected with the injection tower 17 air inlet through the injection tower air inlet pipe 16. The injection liquid circulating pump 19 outlet is connected with the injection tower 17 spray inlet through the injection liquid circulating pipeline 18, the rich liquid heater 24, and the injection liquid circulating pipeline 18 is provided with a bypass, which is the lean liquid production pipe 23. The rich liquid tank 25 is equipped with a rich liquid pump 26 for increasing the injection liquid of the injection tower 17, and the outlet of the rich liquid pump 26 is connected with the injection tower 17 liquid supplement inlet through the rich liquid supplement pipeline 20. In addition, the automatic switch valve provided on the rich liquid supplement pipeline 20 is interlocked with the liquid level transmitter provided on the tower kettle of the injection tower 17, and the injection tower liquid level is low. The injection tower 17 can automatically supplement the liquid. The injection tower 17 tail gas is discharged into the post-processing combustion equipment for deep treatment, at the same time, the pollutants in the exhaust gas are used as fuel for the combustion equipment, reducing the operation cost of the combustion equipment. The second gas concentration detector 42 is installed on the injection tower tail gas pipe 22, which is interlocked with the motor of the injection blower 15, the automatic regulating valve provided on the lean liquid production pipe 23 and the hot fluid inlet pipeline 29.

[0049] Adjusting method: When the second gas concentration detector is lower than the set value, the opening of the automatic regulating valve on the lean liquid production pipe 23, the opening of the automatic regulating valve on the hot fluid inlet pipeline 29, and the running frequency of the injection blower 15 motor can be reduced in sequence in a gradient control manner. When the second gas concentration detector is higher than the set value, the opening of the automatic regulating valve on the lean liquid production pipe 23, the opening of the automatic regulating valve on the hot fluid inlet pipeline 29, and the running frequency of the injection blower 15 motor can be increased in sequence in a gradient control manner.

[0050] About the lean liquid tank and the rich liquid tank:

[0051] The lean liquid tank 11 and the rich liquid tank 25 are respectively connected with the fresh absorption liquid main pipe 30 and the sewage main pipe 31, and the lean liquid tank 11 and the rich liquid tank 25 are respectively provided with liquid level control devices for adjusting the liquid inlet and liquid outlet.

[0052] Specifically, the lean liquid tank 11 is connected with the fresh absorption liquid main pipe 30 through the first fresh absorption liquid supplement pipe 8 provided with an automatic switch valve, the lean liquid supplement pipe 7 is provided with a bypass, i.e. a lean liquid tank blowdown pipe 13, the lean liquid supplement pipe 7 is connected with the sewage main pipe 31 through the lean liquid tank blowdown pipe 13 provided with an automatic switch valve; the lean liquid tank 11 is provided with a liquid level transmitter which is interlocked with the two automatic switch valves and is used for adjusting the liquid inlet and outlet respectively. When the liquid level is low, the fresh absorption liquid main pipe 30 can automatically supplement fresh absorption liquid for the lean liquid tank 11. When the liquid level is high, the lean liquid tank blowdown pipe 13 automatically discharges liquid.

[0053] Similarly, the rich liquid tank 25 is connected with the fresh absorption liquid main pipe 30 through the second fresh absorption liquid supplement pipe 21 provided with an automatic switch valve, the rich liquid supplement pipe 20 is connected with the sewage main pipe through the rich liquid tank blowdown pipe 27 provided with an automatic switch valve; the rich liquid supplement pipe 20 is provided with a bypass, i.e. the rich liquid tank blowdown pipe 27, and the rich liquid tank 25 is provided with a liquid level transmitter which is interlocked with the two automatic switch valves. When the liquid level is high, the rich liquid tank 25 can automatically discharge liquid to the sewage main pipe, and when the liquid level is low, the rich liquid tank 25 can automatically supplement liquid for the spray tower 17.

[0054] Based on the above specific embodiment, the working operation process of the pretreatment system of the present application is as follows:

[0055] The organic exhaust gas enters through the system air inlet main pipe 1, is pressurized by the induced draft fan 2 and introduced into the absorption tower 4 (when the exhaust gas pressure is large, the induced draft fan is not necessary). The absorption tower 4 is provided with an absorption liquid circulating pump 5 and a lean liquid tank 11, the outlet of the absorption liquid circulating pump 5 is connected with an absorption liquid circulating pipe 6, the other end of the absorption liquid circulating pipe 6 is connected with the spray nozzle of the absorption tower 4, and the absorption liquid circulating pipe 6 is provided with a bypass, i.e. a rich liquid production pipe 10, which is connected with the rich liquid tank 25. The lean liquid tank 11 is provided with a lean liquid pump 12 for adding fresh absorption liquid to the absorption tower 4, and the outlet of the lean liquid pump 12 is connected with the liquid supplement port of the absorption tower 4 through the lean liquid supplement pipe 7. After being reduced in concentration by the absorption tower 4, the high-concentration organic exhaust gas is discharged into the post-treatment combustion equipment for further treatment.

[0056] When there is no or only a small amount of organic exhaust gas into the absorption tower 4, the injection system can be opened to increase the gas concentration entering the post-processing combustion device. The injection tower 17 is equipped with an injection liquid circulating pump 19, an injection fan 15, a rich liquid heater 24, a rich liquid tank 25, etc. The inlet of the above-mentioned injection fan 15 is equipped with an air filter 14, and the outlet is connected with the injection tower air inlet through the injection tower air inlet pipe 16. The outlet of the above-mentioned injection liquid circulating pump 19 is connected with the spray port of the injection tower 17 through the rich liquid heater 24 and the injection liquid circulating pipeline 18, and the injection liquid circulating pipeline 18 is provided with a bypass, i.e. a lean liquid extraction pipeline 23, which is connected with the lean liquid tank 11. The rich liquid tank 25 is equipped with a rich liquid pump 26 for increasing the injection liquid of the injection tower 17, and the outlet of the rich liquid pump 26 is connected with the liquid supplement port of the injection tower through the rich liquid supplement pipeline 20. The tail gas of the injection tower 17 is discharged into the post-processing combustion device for deep processing, and at the same time, it supplements the fuel for the combustion device in the form of pollutants in the exhaust gas, thereby reducing the operation cost of the combustion device.

[0057] When the system is stably operated, the absorption liquid circulating pump 5 and the injection liquid circulating pump 19 are continuous operation devices, and two parallel devices are preferably provided, one for use and one for standby. The induced draft fan 2, the injection fan 15, the lean liquid pump 12 and the rich liquid pump 26 are intermittent operation devices.

[0058] Before the tail gas of the absorption tower 4 and the injection tower 17 is connected to the post-processing combustion device, a gas buffer device is preferably provided, and the safety control instrument for the gas inlet of the combustion device can refer to the conventional technical means in the field, which is not included in the configuration of the pre-processing system.

[0059] Embodiment

[0060] A certain fine chemical enterprise, the main pollutants of its process exhaust gas are ethanol, and the exhaust gas is intermittently discharged, with a total exhaust time of about 12 hours per day. The inlet parameters of the above-mentioned exhaust gas into the absorption tower of the embodiment of the present application are as follows: the inlet flow is 2000 m 3 / h, and the ethanol concentration in the inlet is about 5-50 g / m 3 .

[0061] By controlling the operating parameters of the absorption tower, the ethanol concentration of the tail gas of the absorption tower is not more than 20 g / m 3 , and the absorption tower plays a certain pre-processing role. The design gas volume of the post-processing combustion device is 20000 m 3 / h, and the final exhaust gas non-methane total hydrocarbon emission concentration is not more than 20 mg / m 3 , which meets the requirements of the relevant emission standards.

[0062] When the ethanol concentration of the tail gas of the absorption tower is not more than 10 g / m 3When the concentration of the exhaust gas of the absorption tower is lower than 20g / m3, the spray blower of the spray tower is started to increase the concentration of the intake gas of the post-treatment combustion device. 3 The above-mentioned pretreatment system can realize the relative stability of the concentration of the intake gas of the post-treatment combustion device and control the concentration of the intake gas in a proper range, which can not only meet the safe operation of the device but also save the consumption of the supplementary fuel. Moreover, the absorption waste liquid generated by the ordinary absorption method can be used as the spray liquid of the spray tower in the embodiment, which basically achieves zero discharge of waste water and waste liquid.

[0063] The above detailed description of the application is combined with the specific embodiments and exemplary examples, but these descriptions cannot be understood as limiting the application. Those skilled in the art understand that the technical solutions and embodiments of the application can be variously replaced, modified or improved without deviating from the spirit and scope of the application, and these all fall within the scope of the application.

Claims

1. A high concentration batch organic exhaust pretreatment system characterized by, The system comprises an absorption tower, a lean liquid tank, a rich liquid tank and a spraying tower; the absorption tower is connected with a system gas inlet main pipe, and the spraying tower is connected with a spraying fan; tail gas main pipes of the absorption tower and the spraying tower are connected with a post-treatment combustion device respectively; The absorption tower is connected with the lean liquid tank through a lean liquid supplement pipeline, and the lean liquid tank is connected with the spraying tower through a lean liquid extraction pipeline; the absorption tower is connected with the rich liquid tank through a rich liquid extraction pipeline, and the rich liquid tank is connected with the spraying tower through a rich liquid supplement pipeline; the rich liquid of the rich liquid tank enters the tower kettle of the spraying tower as spraying liquid; the organic matter in the spraying liquid is reduced after being sprayed, and the spraying liquid is used as lean liquid and extracted from the tower kettle of the spraying tower through the lean liquid extraction pipeline and then enters the lean liquid tank; A first gas concentration detector is arranged on the tail gas main pipe of the absorption tower, and the first gas concentration detector is interlocked with automatic regulating valves arranged on the lean liquid supplement pipeline and the rich liquid extraction pipeline; a second gas concentration detector is arranged on the tail gas pipe of the spraying tower, and the second gas concentration detector is interlocked with the spraying fan and the automatic regulating valves arranged on the lean liquid extraction pipeline.

2. The high concentration batch organic exhaust pretreatment system of claim 1, wherein, The tower kettle of the absorption tower is connected with spray nozzles of the tower body of the absorption tower through an absorption liquid circulating pump and an absorption liquid circulating pipeline; the absorption liquid circulating pipeline is connected with the rich liquid tank through the rich liquid extraction pipeline; The tower kettle of the spraying tower is connected with spray nozzles of the tower body of the spraying tower through a spraying liquid circulating pump and a spraying liquid circulating pipeline; the spraying liquid circulating pipeline is connected with the lean liquid tank through the lean liquid extraction pipeline.

3. The high concentration batch organic exhaust pretreatment system of claim 2, wherein, The spraying liquid circulating pipeline is connected with the lean liquid tank through the lean liquid extraction pipeline.

4. The high concentration batch organic exhaust pretreatment system of claim 3, wherein, The rich liquid heater is a tube-shell heat exchanger, a hot fluid of the heat exchanger is low-pressure steam or hot flue gas, the spraying liquid in the rich liquid heater passes through the tube side, and the hot fluid passes through the shell side; an automatic regulating valve of a hot fluid inlet pipeline or an outlet pipeline is interlocked with the second gas concentration detector.

5. The high concentration batch organic exhaust pretreatment system of claim 1, wherein, The system gas inlet main pipe is sequentially provided with a pressure transmitter and an automatic switch valve in the direction of gas inlet, and is connected with the absorption tower gas inlet through a induced draft fan; the pressure transmitter, the automatic switch valve and the induced draft fan motor are interlocked.

6. The high concentration batch organic exhaust pretreatment system of claim 1, wherein, The lean liquid tank and the rich liquid tank are respectively connected with a fresh absorption liquid main pipe and a sewage main pipe, and the lean liquid tank and the rich liquid tank are respectively provided with liquid level control devices for adjusting liquid inlet and liquid outlet.

7. The high concentration batch organic exhaust pretreatment system of claim 1, wherein, The absorption liquid is process water or an organic solvent.

8. A high concentration batch organic exhaust gas pretreatment method characterized by, The high-concentration intermittent organic exhaust gas pretreatment system is based on any one of claims 1-7; When the absorption tower tail gas concentration is lower than a first set value, the opening degree of the automatic regulating valve on the lean liquid supplement pipeline or the rich liquid extraction pipeline is reduced; if the absorption tower tail gas concentration is still lower than the first set value, the spraying tower is started to spray; When the spraying tower tail gas concentration is lower than a second set value, the opening degree of the automatic regulating valve on the lean liquid extraction pipeline or the flow of the spraying fan is reduced.

9. The high concentration batch organic exhaust gas pretreatment method according to claim 8, characterized by, When the absorption tower tail gas concentration is higher than the first set value, the opening degree of the automatic regulating valve on the lean liquid supplement pipeline or the rich liquid extraction pipeline is increased; when the spraying tower tail gas concentration is higher than the second set value, the opening degree of the automatic regulating valve on the lean liquid extraction pipeline or the flow of the spraying fan is increased.

10. The high concentration batch organic exhaust gas pretreatment method according to claim 8, characterized by, The spray tower is connected with a rich liquid heater for heating the spray liquid; when the tail gas concentration of the spray tower is higher or lower than a second set value, the heating power of the rich liquid heater is correspondingly reduced or increased.

Images