Efficient and low-consumption combined treatment process for respiratory gas of styrene storage tank

Abstract

The invention belongs to the technical field of industrial waste gas treatment, and discloses an efficient and low-consumption combined treatment process for respiratory gas of a styrene storage tank, the process adopts a combined treatment process of'catalytic polymerization + ozone oxidation + biotrickling filtration 'to treat the respiratory gas of the styrene storage tank, and the process comprises the following specific steps: S1, ceramic catalytic polymerization pretreatment; s2, ozone oxidation treatment; s3, pretreatment before bio-trickling filtration; and S4, treatment in a bio-trickling filter. Rapid polymerization of high-concentration styrene is promoted through the catalytic polymerization reactor, 60% or above of initial pollutants can be removed, the follow-up treatment load is greatly reduced, residual styrene molecular chains are broken into small molecular substances with higher biodegradability through ozone oxidation, and the high-concentration styrene is obtained. And finally, the low-concentration pollutants are deeply degraded through styrene obligate degrading bacteria in the bio-trickling filter, so that the problem that the treatment efficiency is reduced due to polymer blockage in the traditional process is solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of industrial waste gas treatment, and particularly relates to a high-efficiency and low-consumption combined treatment process for styrene storage tank breathing gas. BACKGROUND

[0002] Styrene is an important organic chemical raw material and is widely used in plastic, resin, medicine and other industries, but its strong volatility and self-polymerization characteristics lead to high difficulty in waste gas treatment. At room temperature, styrene can spontaneously polymerize with heat, and with the passage of time, the accumulation of polymers can block the equipment, affect the accuracy of the temperature measurement system, and even cause safety hazards. At present, the styrene waste gas treatment technology mainly adopts condensation oil gas recovery and 'zeolite adsorption / desorption + combustion method', but both methods have significant technical bottlenecks.

[0003] Firstly, the defects of the condensation oil gas recovery mainly lie in three aspects: firstly, the self-polymerization characteristics of styrene cause the condensation system to be unable to defrost, and the pipeline and gas inlet are easily blocked by frozen condensate, causing the fan to run overload and the storage tank to be alarmed for pressure build-up; secondly, high temperature in summer aggravates polymerization in the condensate pipeline, the condensate cannot be effectively recovered, the activated carbon in the adsorption tank is contaminated and saturated, the desorption fails, and finally the VOCs emission exceeds the standard; thirdly, the polymer covers the temperature measurement point, causing the system to misjudge and overcool, which not only wastes energy but also accelerates the damage of the refrigeration equipment.

[0004] The defects of the 'zeolite adsorption / desorption + combustion method' include: firstly, styrene is easy to polymerize and accumulate on the surface of the molecular sieve runner / activated carbon adsorbent during the adsorption / desorption process, causing the adsorbent to be blocked, the system equipment to be damaged, and the removal efficiency to be reduced; secondly, in order to degrade the styrene polymer on the surface of the adsorbent, the desorption temperature is usually required to be higher than 300 DEG C, so the molecular sieve runner and activated carbon adsorption equipment are no longer suitable; thirdly, the adsorption capacity of the molecular sieve runner is small, and sometimes the working conditions with large concentration fluctuations cannot meet the emission standard of styrene.

[0005] In summary, the traditional styrene storage tank breathing gas treatment process has inherent defects such as high energy consumption, unstable operation, high failure rate, high operation cost, and low removal rate. With the gradual implementation of pollution reduction and carbon reduction requirements, developing a new type of high-efficiency and low-consumption styrene storage tank breathing gas treatment process will certainly produce great economic and environmental benefits. SUMMARY

[0006] The purpose of the present application is to provide a high-efficiency and low-consumption combined treatment process for styrene storage tank breathing gas to solve the problems raised in the background art.

[0007] In order to achieve the above object, the present application provides the following technical scheme: a styrene storage tank breathing gas efficient low consumption combined treatment process, which adopts a combined treatment process of "catalytic polymerization + ozone oxidation + biological trickling filtration" to treat the styrene storage tank breathing gas, and the specific steps are as follows:

[0008] S1, ceramic catalytic polymerization pretreatment: the styrene storage tank breathing gas enters the catalytic polymerization reactor through a closed pipeline, so that the styrene waste gas is fully polymerized in the reactor to reduce the styrene concentration in the waste gas;

[0009] S2, ozone oxidation treatment: an ozone dosing pipeline distribution mixer is arranged on the catalytic polymerization reactor, the ozone and the waste gas are fully combined through the mixer, and the styrene waste gas is oxidized by adding ozone to improve the biodegradability of the waste gas and achieve the purpose of partial deodorization;

[0010] S3, biological trickling filtration pretreatment: after the oxidation time of the waste gas in the pipeline is more than 2s, the waste gas enters a specially designed biological trickling filter tower, and the residual ozone in the waste gas is removed by a spraying layer before entering the trickling filter tower;

[0011] S4, biological trickling filter tower treatment: the residual styrene waste gas and part of the oxidized intermediates are biologically oxidized by special styrene microbial degradation bacteria in the upper and lower two sections of the trickling filter tower, and the waste gas is discharged after reaching the standard.

[0012] Preferably, the catalytic polymerization reactor is prepared by impregnating noble metals into a matrix with PDCs as a carrier and sintering into shape, and then the ceramic module is installed in a reaction tank;

[0013] The catalytic polymerization reactor is composed of two parallel box bodies, and the box body is equipped with a differential pressure monitoring device, a temperature sensor and an oxygen content detection device. When the reactor is running, if the differential pressure reaches the design value, the running box body is switched, and the module in the box body reaching the set differential pressure is sent to a qualified unit for regeneration, and the regenerated module is returned to the catalytic polymerization reactor for recycling.

[0014] Preferably, the reaction temperature of the styrene storage tank breathing gas in the catalytic polymerization reactor is 35-50℃, the empty tower gas speed of the reactor is 0.35m / s, and the residence time is 4s.

[0015] Preferably, the ozone dosing pipeline distribution mixer is arranged on the outlet pipeline of the catalytic polymerization reactor, and the ozone is added to oxidize the odor factors and part of the intermediate small molecules.

[0016] Preferably, in the ozone oxidation treatment stage, the ratio of ozone addition amount to styrene waste gas concentration is 0.8:1, and the pipeline wind speed is 6-8m / s, so that the oxidation time can reach more than 2s.

[0017] Preferably, the biological trickling tower is composed of a corrosion-resistant stainless steel tower body, with two upper and lower segmental spherical ceramic filler layers inside, the filler diameter is 2.5 cm, with high specific surface area to promote microbial adhesion, the tower top is equipped with a spiral nozzle spraying system, spraying circulating liquid containing nitrogen and phosphorus nutrients, the liquid-gas ratio is controlled at 0.25%, to ensure the metabolic requirements of microorganisms.

[0018] Preferably, in the biological trickling tower, the concentration of styrene polluted gas stream after pretreatment by catalytic polymerization and ozone oxidation treatment needs to be lower than 200 ppm, the liquid-gas ratio of the circulating liquid is controlled at 0.25%, the operating temperature is at 25-30℃, and the pH of the circulating liquid is between 7.2-8.1.

[0019] Preferably, the biological trickling tower is inoculated with domesticated styrene-specific degrading bacteria to form a 1-3 mm thick biofilm, and the waste gas degradation is achieved through countercurrent contact, the bottom of the biological trickling tower is provided with a grid support filler, and a mist eliminator is installed at the top to prevent liquid droplets from being entrained, and a pH, temperature and gas concentration monitoring system is provided to realize automatic operation and standard emission.

[0020] The beneficial effects of the present application are as follows:

[0021] 1、The present application promotes rapid polymerization of high-concentration styrene through a catalytic polymerization reactor, which can remove more than 60% of the initial pollutants, greatly reducing the subsequent treatment load, and through ozone oxidation, the residual styrene molecular chain is broken into small molecular substances with higher biodegradability, and finally the low-concentration pollutants are deeply degraded by styrene-specific degrading bacteria in the biological trickling tower. At the same time, through the design and automatic control of the parallel catalytic reactor, parameters such as pressure difference and temperature can be monitored in real time, ensuring stable operation when the concentration of waste gas fluctuates, and completely solving the problem of decreased treatment efficiency caused by polymer blockage in traditional processes.

[0022] 2、The "catalytic polymerization + ozone oxidation + biological trickling" combined treatment process used in the present application has low operating energy consumption, and the main energy consumption is only the circulating pump and the fan, and the energy consumption is only 30%-40% of that of the traditional condensation and combustion process. The microbial metabolic process is carried out at normal temperature and pressure without additional heating or pressurization, further reducing energy demand. In addition, the long-term stability of the tower filler and the self-reproduction ability of the microorganisms can avoid the cost of frequent replacement of materials and catalysts.

[0023] 3、The present application completely decomposes the malodor factors in the respiratory gas through ozone oxidation, and cooperates with biological trickling to make the plant boundary odor concentration lower than 500, and the final product of biological trickling is only CO2 and H2O, without secondary pollution, completely meeting the safety specifications of chemical enterprises, effectively reducing the risk of "standard disturbance". BRIEF DESCRIPTION OF DRAWINGS

[0024] Fig. 1 Process flow diagram for the treatment process of the present application;

[0025] Fig. 2 Schematic diagram of the catalytic polymerization reactor of the present application;

[0026] Fig. 3 Schematic diagram of the ozone feeding pipeline distribution mixer of the present application;

[0027] Fig. 4 SEM and TEM photos of the composite ceramic. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0029] As shown in Figs. 1 to 4 The embodiment of the present application provides a high-efficiency and low-consumption combined treatment process for styrene tank breathing gas, which adopts a combined treatment process of "catalytic polymerization + ozone oxidation + biological trickling filtration" to treat the styrene tank breathing gas, and the specific steps are as follows:

[0030] S1, ceramic catalytic polymerization pretreatment: the styrene tank breathing gas enters the catalytic polymerization reactor through a sealed pipeline, so that the styrene waste gas is fully polymerized in the reactor to reduce the styrene concentration in the waste gas;

[0031] In view of the condensation blockage phenomenon existing in the traditional condensation recovery system, in a long-time condensation process, the conveying gas is not smooth and even blocks the gas pipeline, causing high-load operation of the fan and even system failure and other problems. The condensation recovery process of the present application fully utilizes the easy polymerization characteristics of styrene waste gas, promotes and stimulates the polymerization process by setting a "catalytic polymerization" section, and realizes high-efficiency pretreatment of high-concentration raw breathing gas.

[0032] S2, ozone oxidation treatment: an ozone feeding pipeline distribution mixer is arranged on the catalytic polymerization reactor, the mixer is used to realize full combination of ozone and waste gas, and the ozone is used to oxidize the styrene waste gas to improve the biodegradability of the waste gas and achieve the purpose of partial deodorization;

[0033] In view of the fact that the concentration of the styrene waste gas is greatly reduced after pretreatment, but the traditional "adsorption + combustion" combined process is unstable and has high energy consumption, the present application adopts an "ozone oxidation" process to oxidize the styrene waste gas in the pipeline, destroy the molecular structure, and improve the biodegradability of the waste gas.

[0034] S3, biological trickling filter pretreatment: after the oxidation time of waste gas in the pipeline reaches 2s or more, the waste gas enters a specially designed biological trickling filter tower, and the residual ozone in the waste gas is removed by a spraying layer before entering the trickling filter tower;

[0035] S4, biological trickling filter tower treatment: the residual styrene waste gas and part of the oxidized intermediates are biologically oxidized by special styrene microbial degradation bacteria in the upper and lower two sections of the trickling filter tower, and the waste gas is discharged after reaching the standard.

[0036] For the residual styrene waste gas after pretreatment, the traditional adsorption process still has the characteristics of unstable operation, easy polymerization and high energy consumption, and the present application uses the "biological trickling filter" process to realize the biological oxidation of the residual styrene, ensuring efficient degradation and standard emission.

[0037] The breathing gas of the styrene storage tank is connected into the end treatment system through airtight pipeline, and the breathing gas first enters the catalytic polymerization reactor, and the styrene waste gas is fully polymerized in the reactor to reduce the styrene concentration in the waste gas, and then an ozone dosing system distributor is arranged on the outlet pipeline of the reactor to realize the full combination of ozone and waste gas, and the styrene waste gas is oxidized by adding ozone to improve the biodegradability of the waste gas and achieve the purpose of partial deodorization, and when the oxidation time of the waste gas in the pipeline reaches 2s or more, the waste gas enters a specially designed biological trickling filter tower for biological oxidation and deodorization, and a spraying layer is arranged before the waste gas enters the filler bed in the tower to prevent residual ozone from inhibiting the microorganisms in the biological trickling filter tower, and the residual styrene waste gas and part of the oxidized intermediates are biologically oxidized by special styrene microbial degradation bacteria in the upper and lower two sections of the trickling filter tower.

[0038] The "catalytic polymerization + ozone oxidation + biological trickling" combined treatment process used in the present application has low operating energy consumption, and the main energy consumption is only the circulating pump and the fan, and the energy consumption is only 30%-40% of that of the traditional condensation or combustion process, and the microbial metabolic process is carried out at normal temperature and pressure without additional heating or pressurization, further reducing the energy demand, in addition, the long-term stability of the tower filler and the self-reproduction ability of the microorganisms can avoid the cost of frequent replacement of materials and catalysts, and can effectively deal with the situation of large fluctuation and intermittent emission of waste gas.

[0039] The catalytic polymerization reactor is prepared by impregnating noble metals into the matrix with PDCs as the carrier and sintering into shape, and then the ceramic module is installed in the reaction tank.

[0040] The catalytic polymerization reactor is composed of two parallel boxes, and the boxes are equipped with differential pressure monitoring, temperature sensor and oxygen content detection device, when the reactor is running, if the differential pressure reaches the design value, the running box is switched, and the module in the box reaching the set differential pressure is sent to a qualified unit for regeneration, and the regenerated module is returned to the catalytic polymerization reactor for recycling (the ceramic matrix catalytic bed is periodically sent to the manufacturer for combustion regeneration of the polymer bed, and then the regenerated bed is returned to the enterprise reactor for recycling).

[0041] Polymer precursor ceramics (PDCs) are a kind of ceramic materials prepared by high-temperature cracking of silicon-based high molecular organic matter. The composite ceramics prepared by doping metal elements in PDCs can also be used as heterogeneous catalysts. Since PDCs have excellent physical and chemical stability, high temperature resistance, oxidation resistance, molecular designability, controllable composition and microstructure, low preparation temperature and easy formability, the application selects PDCs as the catalyst carrier.

[0042] The reaction temperature of the styrene storage tank breathing gas in the catalytic polymerization reactor is 35-50 DEG C, the empty tower gas speed of the reactor is 0.35 m / s, and the residence time is 4 s.

[0043] The ozone adding pipeline distribution mixer is arranged on the outlet pipeline of the catalytic polymerization reactor, and the ozone is added to oxidize the odor factors and part of the intermediate small molecules.

[0044] The ozone self-decomposition reaction rate constant is 00012 s-1, which can quickly decompose high-activity atomic oxygen to realize the oxidation of odor substances and achieve the purpose of deodorization.

[0045] It should be noted that although ozone can oxidize many organic matters, single ozone oxidation requires a high ozone concentration. Therefore, the distributor is arranged on the outlet pipeline of the catalytic polymerization section to solve the problem.

[0046] The high-concentration styrene is quickly polymerized by the catalytic polymerization reactor, more than 60% of the initial pollutants can be removed, and the subsequent treatment load is greatly reduced. The residual styrene molecular chain is broken into small molecular substances with higher biodegradability by ozone oxidation, and the low-concentration pollutants are deeply degraded by the styrene specific degradation bacteria in the biological trickling filter tower. At the same time, through the design and automatic control of the parallel catalytic reactor, the differential pressure, temperature and other parameters can be monitored in real time, so that the reactor can still operate stably when the waste gas concentration fluctuates, and the problem of decreased treatment efficiency caused by polymer blockage in the traditional process is completely solved.

[0047] The ozone oxidation treatment stage, the ratio of ozone dosage and styrene waste gas concentration is 0.8:1, the pipeline wind speed is 6m / s-8m / s, so as to ensure that the oxidation time can reach more than 2S.

[0048] The biological trickling filter tower is composed of a corrosion-resistant stainless steel tower body, and the inside adopts two-section spherical ceramic filler layers, the filler diameter is 2.5 cm, has a high specific surface area to promote microbial adhesion, and the top is equipped with a spiral nozzle spraying system, sprays the circulating liquid containing nitrogen and phosphorus nutrient solution, and the liquid-gas ratio is controlled at 0.25%, to ensure the metabolic demand of microorganisms.

[0049] The essence of removing styrene waste gas by biological trickling filter tower process is to use the life activity of microorganisms to degrade and eliminate low-concentration pollutants in waste gas

[0050] The concentration of styrene pollution gas flow in the biological trickling filter tower after pretreatment by front-end catalytic polymerization and ozone oxidation treatment needs to be lower than 200ppm, the liquid-gas ratio of the circulating liquid is controlled at 0.25%, the operating temperature is 25℃-30℃, and the pH of the circulating liquid is between 7.2-8.1.

[0051] The biological trickling filter tower is inoculated with domesticated styrene-specific degrading bacteria to form a 1-3mm thick biofilm, and the waste gas degradation is realized through countercurrent contact, the biological trickling filter tower bottom is provided with a grid support filler, the top is installed with a demister to prevent liquid droplets from being entrained, and a pH, temperature and gas concentration monitoring system is matched to realize automatic operation and standard emission.

[0052] Low-concentration styrene waste gas enters from the bottom and is countercurrently contacted with the downward spraying liquid, the pollutants are adsorbed and degraded into CO2 and H2O by the microbial membrane on the surface of the filler, the spraying liquid continuously supplements nutrient salt and adjusts the pH to 7.2-8.1 to maintain microbial activity, and the treated gas is discharged after removing liquid droplets through the demisting layer.

[0053] Through ozone oxidation, the odor factors in the breathing gas are completely decomposed, and the biological trickling filter makes the plant boundary odor concentration less than 500, and the final product of the biological trickling filter is only CO2 and H2O, without secondary pollution, fully meeting the safety specifications of chemical enterprises, effectively reducing the risk of "standard disturbance".

[0054] It is to be understood that the terminology used herein such as first and second, and the like, is only used to distinguish one entity or action from another entity or action, and does not necessarily require or imply any such actual relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0055] While embodiments of the present application have been shown and described with reference to particular embodiments thereof, it will be understood by those skilled in the art that various changes in form and details can be made therein without departing from the spirit and scope of the application. The scope of the application is defined by the appended claims and their equivalents.

Claims

1. A high-efficiency, low-consumption combined treatment process for breathing gas from styrene storage tanks, characterized in that: This process uses a combination of "catalytic polymerization + ozone oxidation + bio-trickling filtration" to treat the breathing gas from styrene storage tanks. The specific steps are as follows: S1, Ceramic Catalytic Polymerization Pretreatment: Styrene storage tank breathing gas enters the catalytic polymerization reactor through a closed pipeline, allowing styrene waste gas to fully polymerize in the reactor, thereby reducing the styrene concentration in the waste gas; S2, Ozone Oxidation Treatment: An ozone dosing pipeline distribution mixer is installed on the catalytic polymerization reactor. The mixer achieves full combination of ozone and waste gas, and the ozone is added to oxidize the styrene waste gas, thereby improving the biodegradability of the waste gas and achieving partial deodorization. S3, Pretreatment before bio-trickling filter: After the waste gas has been oxidized in the pipeline for more than 2 seconds, it enters a specially designed bio-trickling filter tower. Before entering the trickling filter tower, residual ozone in the waste gas is removed by a spray layer. S4, Bio-trickling Filter Treatment: Residual styrene waste gas and partially oxidized intermediate products are bio-oxidized by specialized styrene-degrading microorganisms in the upper and lower packing sections of the trickling filter, and then discharged after the waste gas meets the standards.

2. The efficient and low-consumption combined treatment process for breathing gas from a styrene storage tank according to claim 1, characterized in that: The catalytic polymerization reactor is made by impregnating precious metals into a matrix using PDCs as a carrier and sintering them, and then loading ceramic modules into the reaction vessel. The catalytic polymerization reactor consists of two parallel chambers, each equipped with a differential pressure monitoring system, a temperature sensor, and an oxygen content detection device. During reactor operation, if the differential pressure reaches the design value, the operating chamber is switched, and the module in the chamber that has reached the set differential pressure is sent to a qualified unit for regeneration. The regenerated module is then returned to the catalytic polymerization reactor for recycling.

3. The high-efficiency, low-consumption combined treatment process for breathing gas from styrene storage tanks according to claim 1, characterized in that: The styrene storage tank breathing gas reacts at a temperature of 35℃-50℃ in the catalytic polymerization reactor, with an empty tower gas velocity of 0.35m / s and a residence time of 4s.

4. The efficient and low-consumption combined treatment process for breathing gas from a styrene storage tank according to claim 1, characterized in that: The ozone dosing pipeline distribution mixer is installed on the outlet pipeline of the catalytic polymerization reactor, and oxidizes odor factors and some intermediate small molecules by adding ozone.

5. The efficient and low-consumption combined treatment process for breathing gas from a styrene storage tank according to claim 1, characterized in that: In the ozone oxidation treatment stage, the ratio of ozone dosage to styrene gas concentration is 0.8:1, and the pipeline air velocity is 6m / s-8m / s, thereby ensuring that the oxidation time can reach more than 2 seconds.

6. The efficient and low-consumption combined treatment process for breathing gas from a styrene storage tank according to claim 1, characterized in that: The bio-trickling filter tower is constructed of a corrosion-resistant stainless steel tower body. The interior is filled with two layers of spherical ceramic granules with a diameter of 2.5 cm, which have a high specific surface area to promote microbial attachment. The top of the tower is equipped with a spiral nozzle spraying system to spray a circulating liquid containing nitrogen and phosphorus nutrients. The liquid-to-gas ratio is controlled at 0.25% to ensure the metabolic needs of microorganisms.

7. The efficient and low-consumption combined treatment process for breathing gas from a styrene storage tank according to claim 6, characterized in that: Inside the bio-trickling filter tower, the concentration of styrene pollutant gas after pretreatment by front-end catalytic polymerization and ozone oxidation must be less than 200 ppm, the liquid-to-gas ratio of the circulating liquid must be controlled at 0.25%, the operating temperature must be between 25℃ and 30℃, and the pH of the circulating liquid must be between 7.2 and 8.

1.

8. The high-efficiency and low-consumption combined treatment process for breathing gas from a styrene storage tank according to claim 6, characterized in that: The bio-trickling filter is inoculated with domesticated styrene-specific degrading bacteria to form a 1-3 mm thick biofilm. The biofilm is degraded through countercurrent contact. The bottom of the bio-trickling filter is equipped with a grid to support the packing, and the top is equipped with a demister to prevent droplet entrainment. It is also equipped with a pH, temperature and gas concentration monitoring system to achieve automated operation and emission compliance.

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