Multi-chamber photocatalysis - circulating fluidized bed device

Abstract

The present invention discloses a multi-chamber photocatalytic - circulating fluidized bed device. The device includes a multi-chamber photocatalytic reactor and a circulating fluidized bed connected thereto. The multi-chamber photocatalytic reactor includes a box body, and a light-transmitting partition is arranged inside, dividing the box body into a plurality of connected chambers and a water outlet channel. Ultraviolet light sources are arranged in the chambers, a water inlet is arranged below the box body, and a first air inlet corresponding to the chambers is arranged at the bottom; the circulating fluidized bed includes an upflow bed and a downflow bed, which are respectively connected through a connecting pipe and a circulating pipe up and down. Ultraviolet light sources are arranged in the upflow bed, a second air inlet is arranged below the upflow bed, a water outlet and an inclined plate sedimentation tank are arranged in the downflow bed, and a third air inlet is arranged below the circulating pipe. The present invention uses a fluidized bed reactor in the photocatalytic oxidation reaction and sets up multiple chambers for photocatalytic reaction, effectively improving the utilization rate of light and the removal rate of pollutants, and effectively realizing solid-liquid separation and the recycling of photocatalysts.

Description

Technical Field

[0001] The present invention relates to the technical field of photocatalytic reaction devices, and particularly to a multi-chamber photocatalytic-circulating fluidized bed device. Background Art

[0002] Photocatalysis generates a large amount of organic wastewater in industries such as textile printing and dyeing, papermaking, and pharmaceuticals. Although it is superior to traditional water treatment methods, such as adsorption and precipitation methods, etc., due to involving photocatalytic reactions, problems related to the light propagation rate and utilization rate will be involved. Specifically, in photocatalytic reactions, there are problems such as uneven radiation intensity distribution of the light source in the reactor and serious light intensity attenuation; at the same time, the optimal utilization of the light source, the scattering and absorption of radiation by catalyst particles and bubbles, etc. also need to be considered.

[0003] Fluidized beds are widely used in fields such as petroleum, chemical industry, materials, metallurgy, energy, and environment due to their good mass and heat transfer performance, which is beneficial to improving the contact and transfer effect between fluids and particles.

[0004] Currently, in the field of water treatment, fluidized beds are mostly divided into fluidized bed crystallization reactors and fluidized bed bioreactors. For example, Chinese Patent 1: CN1304884A discloses an external circulation three-phase biological fluidized bed water treatment technology and equipment. The equipment includes a main bed and a secondary bed that are connected up and down through a connecting pipe. The lower part of the main bed is provided with a water inlet and an air inlet, and the upper part of the secondary bed is provided with a water outlet. By designing various parameters, the circulation speed is accelerated to improve the wastewater treatment efficiency. The problems existing in this technical solution are: first, it is mainly based on biological treatment technology, and biological treatment methods cannot bear large pollutant loads and hydraulic shock loads; second, the device is designed in a "barrel" shape, and the circulation resistance of fluids and carriers is large, affecting the treatment efficiency. Chinese Application 2: CN108467135A discloses a fully automatic chemical crystallization circulating granulation fluidized bed water treatment system, which uses chemical crystallization to remove Ca 2+ , Mg 2+ etc. The problems existing in this technical solution are: it is provided with a chemical agent dosing unit and a pH adjustment unit, and these all require dosing chemicals into the water, which is likely to cause secondary pollution of the water body.

[0005] There are not many relevant reports on combining photocatalytic reactions with fluidized beds. There are mainly photocatalytic microreactors, photocatalytic liquid-solid micro-fluidized beds, and photocatalytic gas-liquid micro-bubble column reactors. However, the above microreactors have problems such as small volume, limited treatment capacity, low light utilization rate, and ineffective recycling of catalysts. Summary of the Invention

[0006] In view of the above problems, the object of the present invention is to provide a multi-chamber photocatalytic-circulating fluidized bed device to solve the problems in the prior art such as weak shock resistance of water treatment equipment, low light utilization rate, low treatment efficiency, secondary pollution, and ineffective recycling of catalysts.

[0007] The above object is achieved by the following technical solutions:

[0008] According to one aspect of the present invention, a multi-chamber photocatalytic-circulating fluidized bed device provided by the present invention includes a multi-chamber photocatalytic reactor and a circulating fluidized bed communicated therewith, wherein,

[0009] The multi-chamber photocatalytic reactor includes a box body, and a light-transmitting partition is longitudinally arranged inside the box body. The light-transmitting partition divides the inside of the box body into a plurality of communicating chambers and an outlet channel. The outlet channel is communicated with the lower part of the up-flow bed. Each chamber is provided with an ultraviolet light source. The lower part of the box body is provided with a water inlet, and the bottom of the box body is provided with a plurality of first air inlets corresponding to the chambers one by one;

[0010] The circulating fluidized bed includes an up-flow bed and a down-flow bed. The upper parts of the up-flow bed and the down-flow bed are communicated through a connecting pipe, and the lower parts of the up-flow bed and the down-flow bed are communicated through a circulating pipe. An ultraviolet light source is arranged inside the up-flow bed, and a second air inlet is arranged at the lower part. The down-flow bed is provided with a water outlet and an inclined plate sedimentation tank for solid-liquid separation. A third air inlet is arranged below the circulating pipe; after separation, the photocatalyst solid particles are blown back to the up-flow bed under the action of the air inlet of the third air inlet to complete the circulation of the photocatalyst in the circulating fluidized bed.

[0011] Preferably, an opening is arranged in the middle of the light-transmitting partition, and a guide plate is arranged on the light-transmitting partition below the opening. The elevation angle of the guide plate is 30-50°. More preferably, the opening is arranged in the upper middle part of the light-transmitting partition. More preferably, the elevation angle of the guide plate is 45°.

[0012] Preferably, the light-transmitting partition is made of quartz material.

[0013] Preferably, the inclined plate sedimentation tank is arranged at the lower part of the down-flow bed for solid-liquid separation; the water outlet is arranged on the side wall of the down-flow bed and is higher than the inclined plate sedimentation tank in position. The liquid separated by the inclined plate sedimentation tank can be discharged from the water outlet, and the photocatalyst solid particles precipitate and return to the up-flow bed under the action of the air inlet of the third air inlet to complete the circulation process of the solid particles in the circulating fluidized bed.

[0014] Preferably, the circulating pipe is inclined, and the connection part with the down-flow bed is higher than the connection part with the up-flow bed.

[0015] Preferably, a buffer zone is provided at a position of the circulation pipeline close to the upflow bed, and the third air inlet is located below the buffer zone.

[0016] Preferably, an air inlet device is further included. The air inlet device is connected to the first air inlet, the second air inlet and the third air inlet through an air inlet pipeline, and a check valve is provided on the air inlet pipeline. More preferably, the air inlet device is a blower.

[0017] Preferably, a first exhaust port is provided on the box body, and the first exhaust port is located at the top of the water outlet channel; a second exhaust port is provided at the top of the downflow bed.

[0018] Preferably, an outlet is provided at the lower part of the water outlet channel and is communicated with the lower part of the upflow bed through a conveying pipeline.

[0019] Compared with the prior art, the present invention uses a fluidized bed in a photocatalytic oxidation reaction, adopts a box design, and arranges a multi-compartment structure inside the box, which increases the photocatalytic reaction time, can fully carry out the photocatalytic reaction, enhances the shock resistance ability, effectively improves the light utilization rate, and improves the pollutant removal rate; through the fluidized bed, the effective recycling of the photocatalyst is completed, the effective solid-liquid separation is realized, and the device has the advantages of no secondary pollution and strong shock resistance ability. Description of the Drawings

[0020] Figure 1 is a schematic structural diagram of the multi-compartment photocatalytic-circulating fluidized bed device of the present invention.

[0021] Figure 1 In the figure, 10 is a multi-compartment photocatalytic reactor, 11 is a water inlet, 12 is a first air inlet, 13 is an ultraviolet light source, 14 is a light-transmitting partition plate, 15 is an opening, 16 is a baffle plate, 17 is a conveying pipeline, 18 is a first exhaust port; 20 is a circulating fluidized bed, 21 is an upflow bed, 211 is a second air inlet, 22 is a downflow bed, 23 is a water outlet, 24 is an inclined plate sedimentation tank, 25 is a circulation pipeline, 251 is a third air inlet, 26 is a second exhaust port; 30 is an air inlet device, 31 is a check valve. Detailed Embodiments

[0022] Next, the technical solutions of the present invention will be clearly and completely described in conjunction with the embodiments and drawings of the present invention. In the description of the present invention, it should be understood that the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise stated, the meaning of "a plurality" is two or more.

[0023] Figure 1Schematically shows the structure of the multi-chamber photocatalytic-circulating fluidized bed device of the present invention. As Figure 1 shown, a multi-chamber photocatalytic-circulating fluidized bed device provided by the present invention includes: a multi-chamber photocatalytic reactor 10 and a circulating fluidized bed 20 communicated therewith. Considering the problems involved in photocatalytic reactions such as the propagation and utilization rate of light, and at the same time considering the advantages of strong mixing degree, high mass transfer rate, small temperature gradient, and controllable reaction temperature in fluidized bed reactors, in order to improve the efficiency of photocatalytic reactions, the fluidized bed reactor is used in photocatalytic oxidation reactions, forming the photocatalytic-circulating fluidized bed device with a multi-chamber structure of the present invention, thereby effectively improving the utilization rate of light, increasing the removal rate of pollutants, achieving good solid-liquid separation, realizing the effective recycling of photocatalysts, and the device also has the advantages of not causing secondary pollution and strong shock resistance.

[0024] In the present invention, the multi-chamber photocatalytic reactor 10 includes a box body. An inlet 11 is provided on the box wall at the lower part of the box body, a first air inlet 12 is provided at the bottom of the box body, and one or more light-transmitting partition plates 14 are longitudinally arranged inside the box body. The light-transmitting partition plates 14 divide the interior of the box body into multiple communicating chambers and an outlet channel, and the outlet channel is used to communicate with the up-flow bed 21 of the circulating fluidized bed 20. Water enters from the side wall of the box body and air enters from the bottom of the box body, which can effectively achieve uniform contact of the gas, liquid, and solid phases, increase the removal rate, and improve the photocatalytic reaction efficiency.

[0025] An ultraviolet light source 13, such as an ultraviolet lamp, etc., is provided inside each chamber of the multi-chamber photocatalytic reactor 10. The setting of the multi-chamber structure can increase the reaction time of photocatalysis, extend the residence time of water and catalyst in the chamber, and further make the photocatalytic reaction proceed more fully. Moreover, the multiple chambers are separated by the light-transmitting partition plates 14, and the light-transmitting partition plates 14 can be made of quartz material, which can effectively transmit light, so that light sources can be obtained even in different chambers, thereby improving the utilization rate of light.

[0026] The number of the first air inlets 12 can be the same as the number of chambers and are arranged in one-to-one correspondence. In this way, on the one hand, it can extend the residence time of water and catalyst in the chamber and make the reaction proceed more fully; on the other hand, it can also meet the oxygen demand of the photocatalytic reaction.

[0027] In an alternative embodiment, the multi-compartments can be connected by providing an opening 15 in each light-transmitting partition 14. Preferably, the opening 15 can be provided in the middle or upper-middle part of the light-transmitting partition 14. Further, a flow guiding plate 16 can be provided on the light-transmitting partition 14 below the opening 15. The angle (elevation angle) between the flow guiding plate 16 and the horizontal direction can be 20-50°, for example, 45°. The provision of the above-mentioned opening 15 and flow guiding plate 16 can increase the hydraulic retention time, thereby increasing the photocatalytic reaction time and further improving the sufficiency of the photocatalytic reaction.

[0028] A lower part of the effluent channel is provided with an outlet, which is connected to a lower part of the up-flow bed 21 of the circulating fluidized bed 20 through a conveying pipeline 17, so that water and photocatalyst can undergo photocatalytic reaction again in the up-flow bed 21, thereby improving the pollutant removal rate.

[0029] In the present invention, the circulating fluidized bed 20 includes an up-flow bed 21 and a down-flow bed 22. The upper parts of the up-flow bed 21 and the down-flow bed 22 are connected through a connecting pipeline, and the lower parts of the up-flow bed 21 and the down-flow bed 22 are connected through a circulating pipeline 25. However, it is not limited thereto, and it can also be an integral structure.

[0030] The inside of the up-flow bed 21 is also provided with an ultraviolet light source 13, and a second air inlet 211 is provided at the bottom. The provision of the second air inlet 211 enables the water and photocatalyst transported from the effluent channel to quickly enter the up-flow bed 21, and undergo photocatalytic reaction again in the up-flow bed 21, and then enter the down-flow bed under the pushing action of the inlet air, thereby improving the treatment efficiency of pollutants and minimizing the pollutants at the water outlet 23.

[0031] In an alternative embodiment, a lamella sedimentation tank 24 is provided at a lower part of the down-flow bed 22, that is, near the circulating pipeline 25. A water outlet 23 is provided on the side wall of the down-flow bed 22, and the height of the water outlet 23 is higher than that of the lamella sedimentation tank 24, and the water outlet 23 is located on the side wall of the down-flow bed 22 above the lamella sedimentation tank 24. Optionally, the inner diameter of the top region of the down-flow bed 22 is larger than that of the lower region to play a buffering role. A third air inlet 251 is also provided below the circulating pipeline 25. In the present invention, in order to prevent the photocatalyst from leaking with the effluent, a lamella sedimentation tank 24 is provided in the down-flow bed 22. The lamella sedimentation tank 24 enables the treated water (or wastewater) and the sedimentable photocatalyst (solid particles) to move and separate from each other in the sedimentation shallows, so that the separated solid particles are concentrated in the down-flow bed 22. Through the intake of air through the third air inlet 251, the particles return to the up-flow bed 21 again to undergo photocatalytic reaction again, thereby completing the circulation process of the solid particles in the fluidized bed.

[0032] Preferably, the circulation pipeline 25 is inclined, and the connection with the downcomer bed 22 is higher than the connection with the riser bed 21, so as to assist the completion of the circulation of catalyst particles. Optionally, a buffer zone is provided at the position of the circulation pipeline 25 close to the riser bed 21, and the third air inlet 251 is located below the buffer zone to avoid the problem that the photocatalyst cannot flow upward to the riser bed 21 and cannot circulate effectively due to being pushed by the air flow.

[0033] The multi-chamber photocatalytic-circulating fluidized bed device of the present invention further includes an air inlet device 30, which can be, for example, a blower. The air inlet device 30 is connected to the first air inlet 12, the second air inlet 211 and the third air inlet 251 through an air inlet pipeline, and a check valve 31, such as a one-way pneumatic butterfly valve, is provided on the air inlet pipeline. A first exhaust port 18 is provided on the box body, and the first exhaust port 18 is located at the top of the water outlet channel. A second exhaust port 26 is provided at the top of the downcomer bed 22.

[0034] The working process of the device will be described in detail below with reference to the accompanying drawings:

[0035] Air is introduced into the device through the air inlet device 30. The water containing pollutants enters the interior of the multi-chamber photocatalytic reactor 10 from the water inlet 11 and successively enters the first chamber, the second chamber, and the third chamber. Among them, the catalyst, water, and gas form a three-phase fluidized bed reaction system in the chamber, enabling the catalyst to fully contact the pollutants in the water, and under the irradiation of light, the pollutants are effectively oxidized and decomposed, thereby improving the treatment efficiency of the photocatalytic reaction for pollutants;

[0036] Then, it flows into the water outlet channel from the opening 15 of the third chamber and reaches the lower part of the riser bed 21 through the conveying pipeline 17. Under the action of the ultraviolet light source 13 in the riser bed 21, the photocatalytic reaction continues to further improve the photocatalytic efficiency;

[0037] Next, with the push of the air flow, it enters the downcomer bed 22. The inclined plate sedimentation tank 24 in the downcomer bed 22 separates the photocatalyst (solid particles) from the water. The treated water flows out from the water outlet 23, and the photocatalyst precipitates to the lower part of the inclined plate sedimentation tank 24. The photocatalyst particles are concentrated in the circulation pipeline 25 at the lower part of the downcomer bed 22. By introducing air again through the third air inlet 251, the particles return to the riser bed 21 again, completing the circulation process of the catalyst solid particles in the circulating fluidized bed 20.

[0038] The multi-chamber photocatalysis-circulating fluidized bed device provided above adopts a box design, divides the multi-chamber circulation, and has strong impact resistance. It not only increases the light exposure time, prolongs the residence time of water, and improves the removal rate of pollutants; but also utilizes the characteristics of the inclined plate sedimentation tank 24 to effectively precipitate and reflux the photocatalyst to the photocatalytic reaction area for photocatalytic reaction again, thereby reducing the loss of the photocatalyst and realizing the reuse of the photocatalyst. This device can be flexibly combined with other water treatment processes.

Claims

1. A multi-chamber photocatalytic-circulating fluidized bed device, characterized in that, It includes a multi-chamber photocatalytic reactor and a circulating fluidized bed connected thereto. Among them, the multi-chamber photocatalytic reactor includes a box body. Inside the box body, a light-transmitting partition is longitudinally arranged. The light-transmitting partition divides the interior of the box body into multiple connected chambers and a water outlet channel. The water outlet channel is connected to the lower part of the up-flow bed. Each chamber is provided with an ultraviolet light source. The lower part of the box body is provided with a water inlet. The bottom of the box body is provided with a first air inlet corresponding to each chamber one by one. Among them, an opening is arranged on the light-transmitting partition, and a deflector is arranged on the light-transmitting partition below the opening. The elevation angle of the deflector is 30° to 50°; the circulating fluidized bed includes an up-flow bed and a down-flow bed. The upper parts of the up-flow bed and the down-flow bed are connected through a connecting pipe. The lower parts of the up-flow bed and the down-flow bed are connected through a circulating pipe. Among them, an ultraviolet light source is arranged inside the up-flow bed, and a second air inlet is arranged at the lower part. The down-flow bed is provided with a water outlet and an inclined plate sedimentation tank for solid-liquid separation. A third air inlet is arranged below the circulating pipe, which is used to blow the separated photocatalyst solid particles back to the up-flow bed to complete the circulation of the photocatalyst in the circulating fluidized bed.

2. The multi-chamber photocatalytic-circulating fluidized bed device according to claim 1, characterized in that, The opening is arranged in the upper middle part of the light-transmitting partition, and the elevation angle of the deflector is 45°.

3. The multi-chamber photocatalytic-circulating fluidized bed device according to claim 1, characterized in that, The light-transmitting partition is made of quartz material.

4. The multi-chamber photocatalytic-circulating fluidized bed device according to claim 1, characterized in that, The inclined plate sedimentation tank is arranged at the lower part of the down-flow bed. The water outlet is arranged on the side wall of the down-flow bed, and the position is higher than that of the inclined plate sedimentation tank.

5. The multi-chamber photocatalytic-circulating fluidized bed device according to claim 1, characterized in that, The circulating pipe is inclined, and the connection position with the down-flow bed is higher than the connection position with the up-flow bed.

6. The multi-chamber photocatalytic-circulating fluidized bed device according to claim 1, characterized in that, A buffer area is arranged at the position of the circulating pipe close to the up-flow bed, and the third air inlet is located below the buffer area.

7. The multi-chamber photocatalytic-circulating fluidized bed device according to claim 1, characterized in that, It also includes an air intake device. The air intake device is connected to the first air inlet, the second air inlet and the third air inlet through an air intake pipe. A one-way valve is arranged on the air intake pipe.

8. The multi-chamber photocatalytic-circulating fluidized bed device according to claim 1, characterized in that, A first exhaust port is arranged on the box body, and the first exhaust port is located at the top of the water outlet channel. A second exhaust port is arranged at the top of the down-flow bed.

9. The multi-chamber photocatalytic-circulating fluidized bed device according to claim 1, characterized in that, An outlet is arranged at the lower part of the water outlet channel and is connected to the lower part of the up-flow bed through a conveying pipe.

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