Waste gas treatment system and process for POE alcohol production

Abstract

The invention discloses a waste gas treatment system and process for POE alcohol production. The waste gas treatment system comprises a gas-water separation tank, a homogenization tank, a water washing tower, a Fenton oxidation reactor, an activated carbon adsorption tower, a water absorption tower, a catalytic oxidation reactor and an alkaline washing tower which are sequentially connected through pipelines. The method has the advantages that dust, acid gas, VOCs and trace toxic pollutants in the POE alcohol production waste gas are efficiently removed through a multi-stage cooperative treatment process, meanwhile, the operation cost is reduced, and secondary pollution is avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of POE alcohol production waste gas treatment, in particular to a waste gas treatment system for POE alcohol production and a process thereof. BACKGROUND

[0002] POE polyol ester products are lubricating oil base oils for air compressors, which are widely used in air compressors for household, vehicle, and large air conditioning units, and have excellent viscosity-temperature characteristics and oxidation resistance, and have good compatibility and matching performance with new generation green and environmentally friendly refrigerants. Among ester synthetic oils, complex esters have high viscosity and are easily biodegradable, and are more suitable as base oils for engine oil, refrigerator oil and hydraulic oil with higher environmental protection requirements. At the same time, they have good boundary lubricity and can be used as lubricating oil base oil or lubricating additive.

[0003] The existing POE polyol ester products inevitably produce a large amount of waste gas in the production process. The waste gas sources mainly include process waste gas generated in the production process of various products, non-condensable gas of multi-effect evaporation system, and size breathing waste gas of supporting storage tank. The main pollutants are dust, non-methane total hydrocarbons (organic acids, organic alcohols, etc.). The existing production process does not effectively treat the above waste gas, or the treatment efficiency is relatively low, and the unit treatment cost is high. SUMMARY

[0004] The purpose of the present application is to provide a waste gas treatment system for POE alcohol production and a process thereof. Through a multi-stage collaborative treatment process, efficient removal of dust, acid gas, VOCs and trace toxic pollutants in POE alcohol production waste gas is achieved, while the operating cost is reduced and secondary pollution is avoided.

[0005] The above technical purpose of the present application is achieved by the following technical scheme:

[0006] A waste gas treatment system for POE alcohol production, comprising the following units connected in sequence through pipelines:

[0007] A gas-water separation tank separates water from gas in the waste gas and cools it down;

[0008] A homogenizing tank can homogenize the total hydrocarbon concentration in the waste gas through an internal catalyst;

[0009] A water washing tower preliminarily removes dust, soluble acid gas and part of alcohol monomers soluble in water in the waste gas;

[0010] A Fenton oxidation reactor performs advanced oxidation treatment on the refractory organic matter in the waste gas after water washing, and decomposes it into small molecular organic matter or carbon dioxide and water;

[0011] An activated carbon adsorption tower is used to remove the residual VOCs and odor substances in the waste gas after Fenton oxidation by adsorption;

[0012] A water absorption tower is used to absorb the water-soluble small molecular substances generated or remaining in the waste gas in the previous treatment process;

[0013] A catalytic oxidation reactor is used to completely oxidize the residual VOCs in the waste gas into CO2 and H2O at a fixed temperature;

[0014] An alkali washing tower is used to absorb the acidic gas generated in the catalytic oxidation process and to cool the gas.

[0015] Preferably, the gas inlet end of the gas-water separation tank is also provided with a flame arrester.

[0016] Preferably, the drainage outlets of the gas-water separation tank, the water washing tower and the alkali washing tower are all connected to an MBR biological tank through a pipeline, and the MBR biological tank is connected to an external sewage treatment plant.

[0017] Preferably, the activated carbon adsorption tower is provided with two groups in parallel, one for use and one for backup, and the activated carbon adsorption tower is filled with nitric acid oxidation modified activated carbon.

[0018] Preferably, air induction fans and valves are arranged between each unit in the system, and a heat exchanger and a heater are arranged at the front end of the catalytic oxidation reactor.

[0019] Preferably, the catalytic oxidation reactor is filled with a noble metal catalyst, the carrier of the noble metal catalyst is honeycomb-shaped Al2O3, the active component is Pt-Pd alloy, and the loading amount is 0.3-0.5%.

[0020] Preferably, the alkali solution sprayed in the alkali washing tower is a 5-10%wt NaOH solution.

[0021] Preferably, the exhaust outlet at the top of the alkali washing tower is also connected to an exhaust cylinder through a fan, and the height of the exhaust cylinder is greater than 20m.

[0022] A waste gas treatment process for POE alcohol production, comprising the following steps:

[0023] The waste gas generated in the POE alcohol production process first passes through a flame arrester into a gas-water separation tank, separates most of the water, and then enters a homogenizing tank for homogenization of the total hydrocarbon concentration of the waste gas. Subsequently, it is sent into a water washing tower through an air induction fan, and the spray device of the water washing tower is turned on to make the deionized water and the waste gas contact in the reverse direction in the filler layer. The deionized water spray flow is 5-10m 3 / h, and the residence time of the waste gas in the tower is 10-15s;

[0024] The washed exhaust gas is sent into the Fenton oxidation reactor. At the same time, FeSO4 solution and H2O2 solution are added into the reactor through the reagent addition port. The pH of the solution in the reactor is controlled at 3-4. The agitator and aeration device are turned on to ensure that the exhaust gas and Fenton reagent are fully mixed and reacted. The reaction temperature is controlled at 25-35℃ and the residence time of the exhaust gas in the reactor is 20-30s.

[0025] The waste gas after Fenton oxidation is sent into an activated carbon adsorption tower, and the residence time of the waste gas in the adsorption tower is controlled to be 15-20 seconds.

[0026] The waste gas adsorbed by activated carbon enters the water absorption tower from the bottom and passes through the deionized water tank by pressurized aeration. The residence time of the waste gas in the tower is controlled to be 8-12 seconds.

[0027] After being absorbed by water, the waste gas enters the heat exchanger and heater in sequence, and is finally heated to 250-300℃. The heated waste gas then enters the catalytic oxidation reactor. Under the action of the Pt-Pd alloy catalyst, the trace VOCs in the waste gas are oxidized into CO2 and H2O. The reaction temperature is 300-350℃, and the heat released by the reaction is exchanged with the heat exchanger.

[0028] The catalytically oxidized waste gas is fed into an alkaline scrubbing tower, and the spray system is activated to allow the waste gas and alkaline solution to come into counter-current contact within the packing layer. The spray flow rate is 4-8 m³ / h. 3 / h, the residence time of the exhaust gas in the tower is 12-18s;

[0029] The treated exhaust gas will then be discharged from the exhaust stack via a fan and monitored in real time by an online monitoring device.

[0030] In summary, the present invention has the following beneficial effects:

[0031] 1. This invention achieves comprehensive removal of acidic gases, VOCs, and trace toxic pollutants from POE alcohol production waste gas through a multi-stage synergistic process, ensuring that the concentration of each pollutant in the final exhaust gas meets the emission standards.

[0032] 2. This invention can effectively remove most soluble and oxidizable pollutants through the water washing and Fenton oxidation unit at the front end of the system, greatly reducing the load on the activated carbon adsorption and catalytic oxidation units at the back end, making the system more adaptable to fluctuations in the concentration and composition of exhaust gas and ensuring stable operation.

[0033] 3. The high-temperature purified gas at the outlet of the catalytic oxidation reactor of the present invention preheats the inlet gas through a heat exchanger, recovering part of the reaction heat, effectively reducing the energy consumption for supplementary heating of the system, which is in line with the concept of green chemical industry.

[0034] 4. After treatment using the system of the present invention, the final VOCs concentration at the emission outlet is less than 20 mg / m³.3 The non-methane total hydrocarbon removal rate is >98%, the malodor is completely eliminated, and all indicators are better than the national emission standards. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the overall system connection structure of the present invention. Detailed Implementation

[0036] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. These embodiments do not constitute a limitation on the present invention.

[0037] like Figure 1 The waste gas treatment system shown includes the following units connected in sequence via pipelines:

[0038] Gas-water separator 2 separates the moisture from the gas in the exhaust gas and cools it down;

[0039] The homogenization tank 3 uses an internal catalyst to homogenize the total hydrocarbon concentration in the exhaust gas.

[0040] Water washing tower 4 is used to initially remove dust, soluble acidic gases, and some water-soluble alcohol monomers from the exhaust gas.

[0041] The Fenton oxidation reactor 5 performs advanced oxidation treatment on the recalcitrant organic matter in the waste gas after water washing, decomposing it into small molecule organic matter or carbon dioxide and water.

[0042] Activated carbon adsorption tower 6 adsorbs and removes residual VOCs and malodorous substances from the exhaust gas after Fenton oxidation.

[0043] Water absorption tower 7 absorbs water-soluble small molecule substances in the waste gas that are generated or remain due to previous treatment.

[0044] The catalytic oxidation reactor 8 completely oxidizes the remaining VOCs in the waste gas into CO2 and H2O at a fixed temperature;

[0045] Alkali washing tower 9 absorbs acidic gases produced during catalytic oxidation and cools the gases.

[0046] A flame arrester 1 is also installed at the air inlet end of the gas-water separator 2.

[0047] The drain outlets of the gas-liquid separator 2, the water washing tower 4, and the alkali washing tower 9 are all connected to the MBR biological tank 12 via pipelines, and the MBR biological tank 12 is connected to an external sewage treatment plant.

[0048] Two sets of activated carbon adsorption towers 6 are set up in parallel, one for use and one for standby. The activated carbon adsorption towers 6 are filled with nitric acid oxidation modified activated carbon.

[0049] Each unit in the system is equipped with an induced draft fan and valves, and the front end of the catalytic oxidation reactor 8 is also equipped with a heat exchanger and a heater.

[0050] The catalytic oxidation reactor 8 is filled with a noble metal catalyst. The support of the noble metal catalyst is honeycomb Al2O3, and the active component is a Pt-Pd alloy with a loading of 0.3-0.5%.

[0051] The alkaline solution sprayed inside alkaline washing tower 9 is a 5-10% wt NaOH solution.

[0052] The top exhaust port of the alkali washing tower 9 is also connected to the exhaust stack 11 via the fan 10, and the exhaust stack 11 is more than 20m high.

[0053] A waste gas treatment process for POE alcohol production includes the following steps:

[0054] The waste gas generated during the POE alcohol production process first passes through a flame arrester 1 and then enters a gas-liquid separator 2. After most of the water is separated, it enters a homogenization tank 3 to homogenize the total hydrocarbon concentration of the waste gas. Subsequently, it is sent into a water scrubbing tower 4 by an induced draft fan. The spray device of the water scrubbing tower 4 is turned on, so that deionized water and waste gas come into countercurrent contact within the packing layer. The deionized water spray flow rate is 5-10 m³ / h. 3 The waste gas has a residence time of 10-15 seconds in the tower. Water-soluble VOCs and particulate matter in the waste gas are removed by using washing water through countercurrent spraying.

[0055] The washed exhaust gas is fed into the Fenton oxidation reactor 5. At the same time, FeSO4 solution and H2O2 solution are added into the reactor through the reagent addition port. The pH of the solution in the reactor is controlled at 3-4. The agitator and aeration device are turned on to ensure that the exhaust gas and Fenton reagent are fully mixed and reacted. The reaction temperature is controlled at 25-35℃ and the residence time of the exhaust gas in the reactor is 20-30s. Under acidic conditions, hydroxyl radicals are generated to oxidize and decompose the recalcitrant macromolecular organic matter in the exhaust gas.

[0056] The waste gas after Fenton oxidation is sent into activated carbon adsorption tower 6, and the residence time of the waste gas in the adsorption tower is controlled to be 15-20s. The huge specific surface area and rich pore structure of activated carbon are used to adsorb and remove residual organic pollutants and malodorous substances in the waste gas.

[0057] The waste gas adsorbed by activated carbon enters the water absorption tower 7 from the bottom and passes through the deionized water tank by pressurized aeration. The residence time of the waste gas in the tower is controlled to be 8-12 seconds to capture any activated carbon powder that may escape from the waste gas and residual small molecule organic matter that is easily soluble in water.

[0058] After being absorbed by water, the waste gas enters the heat exchanger and heater in sequence, and is finally heated to 250-300℃. The heated waste gas then enters the catalytic oxidation reactor 8. Under the action of the Pt-Pd alloy catalyst, the trace VOCs in the waste gas are oxidized into CO2 and H2O. The reaction temperature is 300-350℃, and the heat released by the reaction is exchanged with the heat exchanger.

[0059] The catalytically oxidized waste gas is fed into alkaline scrubbing tower 9, and the spray device is turned on, so that the waste gas and alkaline solution come into counter-current contact within the packing layer. The spray liquid flow rate is 4-8 m³ / h. 3 The exhaust gas has a residence time of 12-18 seconds in the tower, which neutralizes and removes any acidic gases it may contain, and reduces the exhaust temperature, ultimately achieving compliance with emission standards.

[0060] The treated exhaust gas will then be discharged from the exhaust stack 11 via fan 10, and monitored in real time by an online monitoring device. The final VOCs concentration at the emission outlet is below 20 mg / m³. 3 Non-methane total hydrocarbon removal rate > 98%.

[0061] This invention achieves comprehensive removal of acidic gases, VOCs, and trace amounts of toxic pollutants from POE alcohol production waste gas through a multi-stage synergistic process, ensuring that the concentration of each pollutant in the final exhaust gas meets the emission standards.

[0062] This invention effectively removes most soluble and oxidizable pollutants through the water washing and Fenton oxidation unit at the front end of the system, greatly reducing the load on the activated carbon adsorption and catalytic oxidation units at the back end. This makes the system highly adaptable to fluctuations in the concentration and composition of exhaust gas and ensures stable operation.

[0063] The high-temperature purified gas at the outlet of the catalytic oxidation reactor of the present invention preheats the inlet gas through a heat exchanger, recovering part of the reaction heat and effectively reducing the energy consumption for supplementary heating of the system, which is in line with the concept of green chemical industry.

[0064] After treatment using the system of this invention, the final VOCs concentration at the emission outlet is less than 20 mg / m³. 3 The non-methane total hydrocarbon removal rate is >98%, the malodor is completely eliminated, and all indicators are better than the national emission standards.

[0065] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art can make various modifications or equivalent substitutions to the present invention within the scope of its essence and protection. Such modifications or equivalent substitutions should also be considered to fall within the protection scope of the present invention.

Claims

1. A waste gas treatment system for POE alcohol production, characterized in that, Includes the following units connected in sequence via pipes: The gas-liquid separator separates the moisture from the gas in the exhaust gas and cools it down. The homogenization tank uses an internal catalyst to homogenize the total hydrocarbon concentration in the exhaust gas. The water washing tower initially removes dust, soluble acidic gases, and some water-soluble alcohol monomers from the exhaust gas. The Fenton oxidation reactor performs advanced oxidation treatment on the recalcitrant organic matter in the waste gas after water washing, decomposing it into small molecule organic matter or carbon dioxide and water. Activated carbon adsorption tower adsorbs and removes residual VOCs and malodorous substances from the exhaust gas after Fenton oxidation. Water absorption towers absorb water-soluble small molecule substances in waste gas that are generated or remain from previous treatment processes. The catalytic oxidation reactor completely oxidizes the remaining VOCs in the waste gas into CO2 and H2O at a fixed temperature; The alkaline scrubbing tower absorbs the acidic gases produced during catalytic oxidation and cools the gases.

2. The waste gas treatment system for POE alcohol production according to claim 1, characterized in that: The gas-water separator is also equipped with a flame arrester at the air inlet.

3. The waste gas treatment system for POE alcohol production according to claim 1, characterized in that: The drain outlets of the gas-liquid separator, water washing tower, and alkali washing tower are all connected to the MBR biological tank via pipelines, and the MBR biological tank is connected to an external wastewater treatment plant.

4. The waste gas treatment system for POE alcohol production according to claim 1, characterized in that: Two sets of activated carbon adsorption towers are connected in parallel, one for use and one for standby. The activated carbon adsorption towers are filled with nitric acid oxidation-modified activated carbon.

5. The waste gas treatment system for POE alcohol production according to claim 1, characterized in that: Each unit in the system is equipped with an induced draft fan and valves, and the front end of the catalytic oxidation reactor is also equipped with a heat exchanger and a heater.

6. The waste gas treatment system for POE alcohol production according to claim 1, characterized in that: The catalytic oxidation reactor is filled with a noble metal catalyst, in which the support is honeycomb Al2O3, the active component is a Pt-Pd alloy, and the loading is 0.3-0.5%.

7. The waste gas treatment system for POE alcohol production according to claim 1, characterized in that: The alkaline solution sprayed in the alkaline washing tower is a 5-10% wt NaOH solution.

8. The waste gas treatment system for POE alcohol production according to claim 1, characterized in that: The top exhaust port of the alkaline washing tower is also connected to an exhaust stack via a fan, and the exhaust stack is greater than 20m in height.

9. A waste gas treatment process for POE alcohol production according to any one of claims 1 to 8, characterized in that: Includes the following steps: The waste gas generated during the POE alcohol production process first passes through a flame arrester into a gas-liquid separator. After most of the water is separated, it enters a homogenization tank to homogenize the total hydrocarbon concentration. Subsequently, it is sent into a water scrubbing tower by an induced draft fan. The spray device of the water scrubbing tower is turned on, so that deionized water and waste gas come into countercurrent contact within the packing layer. The deionized water spray flow rate is 5-10 m³ / h. 3 / h, the residence time of the exhaust gas in the tower is 10-15s; The washed exhaust gas is sent into the Fenton oxidation reactor. At the same time, FeSO4 solution and H2O2 solution are added into the reactor through the reagent addition port. The pH of the solution in the reactor is controlled at 3-4. The agitator and aeration device are turned on to ensure that the exhaust gas and Fenton reagent are fully mixed and reacted. The reaction temperature is controlled at 25-35℃ and the residence time of the exhaust gas in the reactor is 20-30s. The waste gas after Fenton oxidation is sent into an activated carbon adsorption tower, and the residence time of the waste gas in the adsorption tower is controlled to be 15-20 seconds. The waste gas adsorbed by activated carbon enters the water absorption tower from the bottom and passes through the deionized water tank by pressurized aeration. The residence time of the waste gas in the tower is controlled to be 8-12 seconds. After being absorbed by water, the waste gas enters the heat exchanger and heater in sequence, and is finally heated to 250-300℃. The heated waste gas then enters the catalytic oxidation reactor. Under the action of the Pt-Pd alloy catalyst, the trace VOCs in the waste gas are oxidized into CO2 and H2O. The reaction temperature is 300-350℃, and the heat released by the reaction is exchanged with the heat exchanger. The catalytically oxidized waste gas is fed into an alkaline scrubbing tower, and the spray system is activated to allow the waste gas and alkaline solution to come into counter-current contact within the packing layer. The spray flow rate is 4-8 m³ / h. 3 / h, the residence time of the exhaust gas in the tower is 12-18s; The treated exhaust gas will then be discharged from the exhaust stack via a fan and monitored in real time by an online monitoring device.

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