CN111422971A - Fountain catalytic ozonation reaction system - Google Patents

Abstract

The invention relates to a spray-type catalytic ozone oxidation reaction system, which comprises at least one reaction tower, a water inlet pipe, a drain pipe, an ozone air distribution pipe and an air exhaust pipe, wherein the reaction tower is a packing spray tower and includes a packing with a catalyst Section, the water inlet pipe is connected to the reaction tower to introduce waste water into the reaction system, the drain pipe is connected to the reaction tower to discharge the waste water from the reaction system, the ozone gas distribution pipe is connected to the reaction tower to introduce ozone into the reaction system, and the exhaust pipe is connected to the reaction tower. The residual ozone and gas after the catalytic reaction are discharged from the reaction system, and the flow direction of the wastewater in the packing section of the reaction tower is opposite to the flow direction of ozone in the packing section of the reaction tower to realize the gas-water countercurrent contact reaction. According to the spray-type catalytic ozone oxidation reaction system of the present invention, the reaction area is increased by spraying, the ozone and the catalyst have a larger contact area, and the ozone is more likely to penetrate the liquid film and reach the catalyst surface, because in the gaseous state Ozone distribution is faster and easier.

Description

A spray type catalytic ozone oxidation reaction system

technical field

The invention relates to wastewater treatment, and more particularly to a spray-type catalytic ozone oxidation reaction system.

Background technique

With the rapid development of my country's industry and agriculture, there are more and more toxic or refractory organic substances in water, and how to deal with such substances and improve their treatment effect has become a more concerned topic in the water treatment industry. Advanced Oxidation Processible (AOP), the oxidation process in which hydroxyl radicals are the main oxidant in the water treatment process is called AOP process. Ozone catalytic oxidation is a commonly used advanced oxidation technology. It is easy to obtain, does not require complex equipment, and is environmentally friendly. It has been gradually used in various chemical, dye, pesticide and other wastewater treatment projects, and has good application prospects. Ozone catalytic oxidation has broad application prospects in the treatment of chemical wastewater, printing and dyeing wastewater, etc., especially in advanced wastewater treatment due to its unique advantages.

Ozone advanced oxidation is an important method to remove organic pollutants in water treatment technology, which can degrade many organic substances and improve their biodegradation performance. When using the ozone process to treat industrial wastewater, the production cost of ozone gas, the uniformity of ozone mixing in water, the contact reaction between ozone and pollutants, and the overall utilization efficiency of ozone gas need to be considered. Therefore, designing a reactor that is conducive to the diffusion of ozone gas in the wastewater and that the reaction substrates can be fully mixed is of great significance for improving the efficiency of wastewater treatment, reducing the process cost, and realizing the functional characteristics of catalytic ozone. However, at present, the research and development of ozone catalytic oxidation is mostly concentrated in the research and development of catalysts, while the research and development of ozone catalytic oxidation reactors is less improved, and the existing ozone catalytic oxidation reactors have low catalyst bed porosity and low ozone utilization. At the same time, there are also problems such as difficulty in separating gas, liquid and solid, difficult recycling of catalyst, complicated backwash operation and poor effect.

The reactor form of catalytic ozone in the prior art is mainly in the form of a fluidized bed or a fixed bed. higher.

The existing ozone catalytic oxidation reaction tower generally adopts the form of a bubbling tower to carry out the gas-liquid contact reaction, that is, the ozone gas is diffused into bubbles through a gas aeration pipe or aeration plate and then released into the waste water of the tower body. Mixing gas and water to achieve mass transfer between gas and liquid and the degradation of pollutants occurs. There are two key problems in the reactor in the form of a bubble column. First, in order to improve the mass transfer efficiency, it is necessary to reduce the size of the bubbles, thereby increasing the contact area between the ozone gas and the wastewater. This requires the use of a microporous aeration disc to disperse the introduced ozone gas into tiny bubbles, and the microporous aeration disc is easily blocked and needs to be cleaned frequently. Second, in order to improve the mass transfer rate of ozone, it is necessary to maintain a higher liquid level in the reactor by increasing the ozone concentration or increasing the column height to increase the partial pressure of ozone to increase the driving force for mass transfer. However, the gas supply pressure of the ozone generator is generally only a maximum pressure of 1.2 kg, that is, a water depth of 12 meters, which limits the continuous increase of the height of the ozone catalytic oxidation reaction tower. That is to say, the current catalytic system has long reaction time, large catalyst filling, serious catalyst loss, high requirements for ozone aeration, requiring microbubbles, and high tower height to increase the partial pressure of ozone to improve ozone mass transfer. And other issues.

SUMMARY OF THE INVENTION

In order to solve the problems of the catalytic ozone oxidation reaction system in the prior art, such as easy blockage, difficult cleaning of the aeration head, low ozone utilization rate, long reaction time, limited tower height, etc., the present invention provides a spray type catalytic ozone oxidation reaction system.

The invention provides a spray type catalytic ozone oxidation reaction system, which comprises at least one reaction tower, a water inlet pipe, a drain pipe, an ozone air distribution pipe and an air exhaust pipe, wherein the reaction tower is a packing spray tower and includes a packing with catalyst Section, the water inlet pipe is connected to the reaction tower to introduce waste water into the reaction system, the drain pipe is connected to the reaction tower to discharge the waste water from the reaction system, the ozone gas distribution pipe is connected to the reaction tower to introduce ozone into the reaction system, and the exhaust pipe is connected to the reaction tower. The residual ozone and gas after the catalytic reaction are discharged from the reaction system, and the flow direction of the wastewater in the packing section of the reaction tower is opposite to the flow direction of ozone in the packing section of the reaction tower to realize the gas-water countercurrent contact reaction.

Preferably, the reaction tower includes a spray section located above the packing section, and a water distribution device for forming the waste water into fine droplets and mist droplets is arranged in the spray section, and the water distribution device is connected with the water inlet pipe.

Preferably, the reaction tower includes a mist removal section located above the spray section, and the mist removal section is connected to an exhaust pipe.

Preferably, a mist eliminator for removing liquid droplets and mist droplets entrained in the gas is provided in the mist removal section.

Preferably, the reaction tower includes an inlet section located below the packing section, and the inlet section is connected with the ozone gas distribution pipe.

Preferably, the reaction tower includes a water trough section located below the air inlet section, and the water trough section is connected with a drainage pipe.

Preferably, the water tank section is connected to the water inlet pipe through a circulating pump.

Preferably, the spray-type catalytic ozone oxidation reaction system comprises a first reaction tower and a second reaction tower connected in series, a water inlet pipe is connected to the first reaction tower to introduce waste water into the reaction system, and a drain pipe is connected to the second reaction tower to The waste water is discharged from the reaction system. The ozone gas distribution pipe is connected to the second reaction tower to introduce ozone into the reaction system. The exhaust pipe is connected to the first reaction tower to discharge the residual ozone and gas after the catalytic reaction from the reaction system. The flow direction of the waste water and The flow direction of ozone realizes the gas-water countercurrent contact reaction in the spray-type catalytic ozone oxidation reaction system.

Preferably, the inlet section of the first reaction tower communicates with the exhaust pipe of the second reaction tower.

Preferably, the water tank section of the first reaction tower is connected to the water inlet pipe of the second reaction tower through a circulating pump.

According to the spray-type catalytic ozone oxidation reaction system of the present invention, the reaction area is increased by spraying, the ozone and the catalyst have a larger contact area, and the ozone is more likely to penetrate the liquid film and reach the surface of the catalyst, because in the gaseous state Ozone distribution is faster and easier, and because the catalyst is not immersed in the wastewater, only a thin liquid film is formed on the surface of the catalyst. According to the spray-type catalytic ozone oxidation reaction system of the present invention, when the pH value of the wastewater does not need to be adjusted, the ozone catalyst is used as a filler, and the wastewater infiltrates the catalyst to form a very thin liquid film on its surface, so that the reaction system has a very large The specific surface area of the reaction is high, and the ozone introduced from the lower part can easily penetrate the liquid membrane and reach the surface of the catalyst. The catalytic ozone oxidation reaction system according to the present invention has the advantages of fast reaction speed, sufficient reaction, high ozone utilization rate, short effective reaction time and hydraulic retention time, stable effluent quality after treatment, convenient catalyst replacement, simple ozone gas supply mode, and system operation and stability. It has the advantages of convenient maintenance, etc., and at the same time solves the problem of limited tower height. In areas with limited land, the tower height can be appropriately increased.

Description of drawings

1 is a schematic diagram of a spray-type catalytic ozone oxidation reaction system according to a preferred embodiment of the present invention;

2 is a schematic diagram of a spray-type catalytic ozone oxidation reaction system according to another preferred embodiment of the present invention.

Detailed ways

Below in conjunction with the accompanying drawings, preferred embodiments of the present invention are given and described in detail.

Example 1

As shown in FIG. 1, a spray-type catalytic ozone oxidation reaction system according to a preferred embodiment of the present invention includes a reaction tower 1, a water inlet pipe 2, a drainage pipe 3, an ozone air distribution pipe 4 and an air exhaust pipe 5, wherein the reaction tower 1 is a packing spray tower, the water inlet pipe 2 is connected to the reaction tower 1 to introduce the waste water into the reaction system, the drain pipe 3 is connected to the reaction tower 1 to discharge the waste water from the reaction system, and the ozone gas distribution pipe 4 is connected to the reaction tower 1 to discharge the ozone. The reaction system is introduced, and the exhaust pipe 5 is connected to the reaction tower 1 to discharge ozone from the reaction system. The flow direction of the wastewater in the reaction tower 1 is opposite to the flow direction of the ozone in the reaction tower 1 .

The reaction tower 1 includes a mist removal section 11, a spray section 12, a packing section 13, an inlet section 14 and a water tank section 15, which are arranged in sequence from top to bottom, wherein the spray section 12, the packing section 13 and the inlet section 14 are provided between the mist removal section 11 at the top and the water tank section 15 at the bottom.

A demister 111 is provided in the defogging section 11 , and the droplets and mist droplets entrained in the gas entering the defogging section 11 are removed by the demister 111 . The top of the defogging section 11 is connected to an exhaust pipe 5 , and the reacted gas and residual ozone are discharged from the reaction tower 1 through the exhaust pipe 5 . In this embodiment, the exhaust pipe 5 is connected to the ozone destructor through a fan to ensure that the emission concentration of ozone meets the emission requirements.

A water distribution device 121 is arranged in the spray section 12, the water distribution device 121 is connected with the water inlet pipe 2, and the waste water enters the reaction tower 1 through the water inlet pipe 2 and the water distribution device 121, forming numerous fine droplets and mist droplets. The residual ozone from the packing section 13 rises into the spray section 12 and is fully mixed and contacted with the droplets and mist droplets to continue to react.

A catalyst 131 is fixed in the packing section 13, the waste water from the water distribution device 121 is evenly sprayed on the catalyst 131, a liquid film is formed on the surface of the catalyst 131, the ozone from the air inlet section 14 rises to the packing section 13, and the gas and water Reverse contact, fully react on the surface of catalyst 131, ozone is converted into hydroxyl radical HO· under the action of catalyst 131, and reacts quickly with organic matter in wastewater. It should be understood that the catalyst 131 can use iron-based catalysts, transition metal oxide catalysts, noble metal catalysts, catalysts supported by ceramsite, catalysts supported by alumina, catalysts supported by activated carbon. There is no specific requirement for the shape of the catalyst 131, which can be spherical, amorphous, honeycomb, shavings, Raschig rings, Pall rings and other forms suitable for packed towers. Of course, the larger the specific surface area, the better, so that the reaction area will be larger, the porosity will be higher, the probability of being blocked is lower, and a smaller gas-water ratio design can be used, so that the amount of wastewater treatment will increase. Obviously, the spray-type catalytic ozone oxidation reaction system provided by the present invention forms a large liquid film surface on the surface of the catalyst packing, creates a good gas-liquid contact area, and reacts quickly.

The air inlet section 14 is connected with the ozone gas distribution pipe 4 , and ozone is passed into the reaction tower 1 through the ozone gas distribution pipe 4 , quickly fills the space of the air inlet section 14 , and then evenly rises to the packing section 13 . Compared with the microporous aeration disc in the prior art, the air distribution pipe of the present invention has a larger aperture and is less prone to blockage.

The bottom of the water tank section 15 is connected with a drain pipe 3 , and the waste water from the air intake section 14 can be discharged through the drain pipe 3 after entering the water tank section 15 . In this embodiment, the water tank section 15 is connected to the water inlet pipe 2 through the circulating pump 6 , so that the circulating water can be drawn from the water tank section 15 by the circulating pump 6 and passed into the reaction tower 1 together with the waste water.

According to the spray-type catalytic ozone oxidation reaction system of the present invention, the reaction system is no longer filled with water, and the reaction is only carried out on the surface flowing through the catalyst packing, which greatly reduces the resistance of the catalytic oxidation reaction tower per unit height. In addition, the existing reaction towers all need to be relatively high, generally at least greater than 6 meters, and some reach 10 meters, because the ozone concentration in the gas supply source is relatively low (the highest is 10-15%, the current ozone generator technology In order to improve the mass transfer efficiency, it is necessary to design a higher reactor height to increase the partial pressure of ozone to improve the ozone mass transfer, but the actual catalyst layer height is limited, that is, the effective reaction area is not high. Correspondingly, the spray type catalytic ozone oxidation reaction system of the present invention does not need a higher tower height, and the general spray tower height can be, for example, 4-6 meters, and the air supply pressure is not required, and there is a little pressure such as 0.05 kg. Ozone can be introduced, because the gas will travel with the direction of the airflow when the water and gas are in contact, and the resistance loss of the gas passing through the packing layer does not exceed 0.04 kg, so the intake pressure can be greater than 0.05 kg. In areas with limited land use, the tower height can be increased to reduce the footprint.

Take the secondary biochemical effluent of a sewage treatment station of a printing and dyeing plant, COD is 140mg/L, chroma 100, aniline 4mg/l, adopt the form of spray tower, the filler is iron-based catalyst, the reaction time is 10min, the dosage of _O3 is 80mg /l, after the catalytic oxidation reaction, the COD is 58mg/L, the chroma is 16, and aniline is not detected, the COD removal rate is over 50%, and the effluent quality reaches the experimental expectation. At the same time, a conventional tower reactor with a fully immersed catalyst was used, the catalyst was still an iron-based catalyst, the reaction time _of O catalytic oxidation was 30min, the dosage _of O was 100 mg/l, the COD after the catalytic oxidation reaction was 60 mg/L, and the chromaticity was 60 mg/L. 20. Aniline was not detected, and the COD removal rate was over 50%. Comparing the two reaction forms, the treatment effect is very close, but the reaction time is greatly shortened, and the utilization rate of ozone is higher.

Example 2

As shown in FIG. 2 , the spray-type catalytic ozone oxidation reaction system according to another preferred embodiment of the present invention includes a first reaction tower 1A, a second reaction tower 1B, a water inlet pipe 2 ′, a drainage pipe 3 ′, an ozone The air distribution pipe 4' and the exhaust pipe 5', wherein the water inlet pipe 2' is connected to the first reaction tower 1A to introduce waste water into the reaction system, and the drain pipe 3' is connected to the second reaction tower 1B to discharge the waste water from the reaction system, The ozone distribution pipe 4' is connected to the second reaction tower 1B to introduce ozone into the reaction system, and the exhaust pipe 5' is connected to the first reaction tower 1A to discharge ozone from the reaction system, which can further improve the utilization of ozone compared with Example 1 It can be used for wastewater treatment requirements with higher discharge standards. In this embodiment, the first reaction tower 1A and the second reaction tower 1B are both two-phase countercurrent packing reaction towers, and the specific structures of the reaction towers 1 and the reaction tower 1 in Example 1 are not repeated here. Explain the different parts.

The inlet section 14 of the first reaction tower 1A is communicated with the exhaust pipe 5B of the second reaction tower 1B, and the exhaust gas collected from the exhaust pipe 5B of the second reaction tower 1B still contains unreacted ozone, which passes through the inlet and outlet. The gas section 14A enters the first reaction tower 1A for reaction.

The water tank section 15A of the first reaction tower 1A is connected to the water inlet pipe 2B of the second reaction tower 1B through the circulating pump 7, so that the circulating water extracted from the water tank section 15A of the first reaction tower 1A through the circulating pump 7 can be connected with the circulating pump 6B. The circulating water extracted from the water tank section 15B of the second reaction tower 1B is passed into the second reaction tower 1B together.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the scope of the present invention. Various changes can be made to the above-mentioned embodiments of the present invention. That is, all simple and equivalent changes and modifications made according to the claims and descriptions of the present invention fall into the protection scope of the claims of the present invention. What is not described in detail in the present invention is conventional technical content.

Claims (10)

1. The utility model provides a fountain catalytic ozonation reaction system, characterized in that, this fountain catalytic ozonation reaction system includes at least one reaction tower, the inlet tube, the drain pipe, ozone gas distribution pipe and exhaust pipe, wherein, the reaction tower is the filler spray tower and includes the filler section that has the catalyst, the inlet tube is connected in the reaction tower in order to introduce waste water into reaction system, the drain pipe is connected in the reaction tower in order to discharge waste water from reaction system, ozone gas distribution pipe is connected in the reaction tower in order to introduce ozone into reaction system, the exhaust pipe is connected in the reaction tower in order to discharge residual ozone and the gas after the catalytic reaction from reaction system, the flow direction of waste water in the filler section of reaction tower is opposite with the flow direction of ozone in the filler section of reaction tower in order to realize the gas-water countercurrent contact reaction.

2. The spray-type catalytic ozonation reaction system according to claim 1, wherein the reaction tower comprises a spray section located above the packing section, a water distribution device for forming fine liquid droplets and fog droplets in the wastewater is arranged in the spray section, and the water distribution device is connected with the water inlet pipe.

3. The spray catalytic ozonation reaction system of claim 2, wherein the reaction tower comprises a demisting section located above the spray section, and the demisting section is connected with the exhaust pipe.

4. The spray catalytic ozonation reaction system of claim 3, wherein a demister for removing liquid droplets and mist droplets entrained in the gas is disposed in the mist elimination section.

5. The spray catalytic ozonation reaction system according to claim 1, wherein the reaction tower comprises an air inlet section located below the packing section, and the air inlet section is connected with the ozone distribution pipe.

6. The spray catalytic ozonation reaction system of claim 5, wherein the reaction tower comprises a water tank section located below the gas inlet section, and the water tank section is connected with a drain pipe.

7. The spray catalytic ozonation reaction system of claim 6, wherein the water tank section is connected to the water inlet pipe by a circulation pump.

8. The spray catalytic ozonation reaction system of claim 1, comprising a first reaction tower and a second reaction tower connected in series, wherein the water inlet pipe is connected to the first reaction tower to introduce wastewater into the reaction system, the water outlet pipe is connected to the second reaction tower to discharge wastewater from the reaction system, the ozone distribution pipe is connected to the second reaction tower to introduce ozone into the reaction system, the air outlet pipe is connected to the first reaction tower to discharge residual ozone and gas after catalytic reaction from the reaction system, and the flow direction of wastewater and the flow direction of ozone realize gas-water countercurrent contact reaction in the spray catalytic ozonation reaction system.

9. The spray catalytic ozonation reaction system of claim 8, wherein the air inlet section of the first reaction tower is communicated with the exhaust duct of the second reaction tower.

10. The spray catalytic ozonation reaction system of claim 8, wherein the water tank section of the first reaction tower is connected with the water inlet pipe of the second reaction tower through a circulating pump.

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