Volatile organic compounds (VOCs) porous medium catalytic oxidation device capable of actively and accurately controlling temperature and method thereof

Abstract

The invention discloses a VOCs porous medium catalytic oxidation device capable of actively and accurately controlling temperature and a method of the VOCs porous medium catalytic oxidation device. Belongs to the technical field of VOCs treatment. The device comprises a gas inlet system, a preheating system, a reaction chamber, a heating system, a cooling system and a gas outlet system, the reaction chamber is filled with at least two porous medium catalyst layers, a temperature sensor is arranged on the wall surface, the heating system surrounds the reactor, the power of each heating unit is controlled by a temperature controller according to the feedback of the sensor, and the cooling system is started when the temperature is too high. The treatment method comprises the following steps: VOCs gas is preheated and then enters the reaction chamber, the temperature controller compares information of the sensor with a preset optimal temperature range and regulates and controls the heating or cooling system, so that the reaction is carried out in the optimal temperature range, and purified gas after the reaction is discharged through the gas outlet system and is further purified and discharged after reaching the standard. According to the invention, the utilization rate of the catalyst is increased, the purification efficiency is improved, the heating and cooling systems are synergistic, the service life of the catalyst is prolonged, and the energy consumption and cost are reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of VOCs treatment, and relates to a VOCs porous medium catalytic oxidation device with active and precise temperature control and a method thereof. Background Art

[0002] As an important precursor of ground-level ozone, particulate matter and secondary aerosols, volatile organic compounds (VOCs) are one of the important causes of haze, photochemical smog and greenhouse effect. In addition, many VOCs are highly irritating, toxic and carcinogenic, and can easily cause a series of health problems including headaches, nausea, respiratory irritation and visceral damage. In recent years, industrial source VOCs emissions caused by industrial production processes such as chemical plants, refineries, printing plants, food processing and textiles have become one of the most abundant and harmful pollutants in the air environment.

[0003] Increasingly stringent regulatory measures and environmental quality requirements have prompted the continuous development of industrial source VOCs treatment technology. Traditional thermal treatment direct-fired furnaces (TO) require a large amount of auxiliary fuel, have high energy consumption, and it is difficult to stably control the temperature above 780°C, affecting the treatment efficiency of exhaust gas. The catalytic combustion (CO) technology evolved on this basis reduces the reaction temperature to below 400°C, with lower energy consumption and higher purification efficiency. However, due to the large amount of heat released during the catalytic combustion process, the catalytic bed still has local overheating, uneven temperature distribution, reduced catalyst treatment efficiency, and even deactivation. Summary of the invention

[0004] In view of the above problems, the purpose of the present invention is to propose a VOCs porous media catalytic oxidation device and method with active and precise temperature control, wherein multiple layers of porous media catalysts with different pore sizes are compactly arranged, which enhances the internal heat storage and thermal conductivity while increasing the contact area and time between the surface and volatile organic compounds, thereby increasing the utilization rate of the catalyst and improving the purification efficiency; the heating and cooling systems work together to avoid local overheating or overcooling, extend the service life of the catalyst, and reduce energy consumption and costs.

[0005] The technical solution of the present invention is: the VOCs porous medium catalytic oxidation device with active and precise temperature control described in the present invention comprises an air intake system, a preheating system, a reaction chamber, a heating system, a cooling system and an air outlet system;

[0006] The air intake system, preheating system, reaction chamber and air outlet system are connected in sequence.

[0007] Furthermore, the air intake system includes an air intake pipeline and a gas flow regulating valve, which are used to regulate and transport the VOCs gas into the reaction device;

[0008] The VOCs gas flow rate is controlled at 1-10m 3 / h range.

[0009] Furthermore, the preheating system is arranged on the air inlet pipe, and is used to preheat the VOCs gas entering the reaction device so that it reaches the starting temperature range required for the reaction;

[0010] The preheating temperature is controlled within the range of 180-300°C.

[0011] Furthermore, the interior of the reaction chamber is filled with at least two porous medium catalyst layers, and the VOCs gas undergoes a catalytic oxidation reaction with oxygen in the reaction chamber under the action of the porous medium catalyst and is processed, and a plurality of temperature sensors are provided on the wall of the reaction chamber for real-time monitoring of the temperature at different positions in the reaction chamber;

[0012] The porous medium catalyst layers are arranged in series, and the porosity increases continuously along the VOCs airflow direction.

[0013] The porous catalyst is a supported noble metal catalyst, a transition metal oxide catalyst and a composite oxide catalyst.

[0014] Furthermore, the porosity of the porous medium catalyst layer is in the range of 0.3 to 0.8.

[0015] Furthermore, the heating system is arranged around the reaction chamber, and includes a plurality of heating units, each of which is connected to a temperature controller, and the temperature controller controls the power of the corresponding heating unit according to the temperature information fed back by the temperature sensor.

[0016] Furthermore, the cooling system is connected to the reaction chamber and includes a cooling pipe and a cooling medium circulation pump. When the temperature in the reaction chamber is too high, the cooling system starts;

[0017] The cooling medium is water or air.

[0018] Furthermore, the gas outlet system includes a gas outlet pipeline and a gas purification device, which is used to discharge the purified gas after the reaction out of the reaction device and perform further purification treatment;

[0019] The gas purification device is an activated carbon adsorption device.

[0020] Furthermore, a treatment method of a VOCs porous medium catalytic oxidation device with active and precise temperature control comprises the following steps:

[0021] Step 1: VOCs gas of a certain concentration enters the preheating system through the air intake system and is preheated to the reaction starting temperature of 180-300°C;

[0022] Step 2: The preheated gas enters the reaction chamber and undergoes a catalytic oxidation reaction with oxygen under the action of the porous medium catalyst. During the reaction, the temperature sensor in the reaction chamber monitors the temperature in real time and transmits the temperature information to the temperature controller;

[0023] Step 3: The temperature controller compares the received temperature information with the preset optimal reaction temperature range. If the temperature is lower than the optimal reaction temperature range, the temperature controller increases the power of the corresponding heating unit to increase the temperature in the reaction chamber; if the temperature is higher than the optimal reaction temperature range, the cooling system is started to reduce the temperature in the reaction chamber so that the reaction is always carried out within the optimal temperature range;

[0024] Step 4: The purified gas after the reaction is discharged from the reaction device through the gas outlet system, and is further treated by the gas purification device before meeting the emission standards.

[0025] Furthermore, in step 1, the concentration of the VOCs gas is 2000-10000 mg / m 3 ;

[0026] In step 2, the residence time of the VOCs gas in the reaction chamber is 0.75 to 2 seconds;

[0027] In step three, the temperature fluctuation of the porous medium catalyst layer in the reaction chamber is ±10° C., and the temperature control response time is ≤0.5 s.

[0028] The beneficial effects of the present invention are: 1. By compactly arranging multiple layers of porous media catalysts with different pore sizes, the internal heat storage and thermal conductivity are enhanced while increasing the contact area and time between the surface and volatile organic matter, thereby increasing the utilization rate of the catalyst and improving the purification efficiency; 2. The heating and cooling systems work together to avoid local overheating or overcooling, thereby extending the service life of the catalyst and reducing energy consumption and costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0030] Figure 2 is a schematic structural diagram of a porous catalyst layer provided in Example 1 of the present invention;

[0031] Figure 3 is a schematic structural diagram of a porous catalyst layer provided in Example 2 of the present invention;

[0032] Figure 4 is a schematic structural diagram of a porous catalyst layer provided in Comparative Example 1 of the present invention;

[0033] In the figure, 1 is an air inlet pipe, 2 is a gas flow regulating valve, 3 is a preheating system, 4 is a reaction chamber, 5 is a porous medium catalyst, 6 is a temperature sensor, 7 is a heating unit, 8 is a temperature controller, 9 is a cooling pipe, 10 is a cooling medium circulation pump, 11 is an air outlet pipe, and 12 is a gas purification device. DETAILED DESCRIPTION

[0034] The specific technical scheme of the present invention is further described in detail below with reference to specific examples.

[0035] like Figure 1 As shown, the VOCs porous medium catalytic oxidation treatment device with active and precise temperature control described in the present invention includes an air intake system, a preheating system 3, a reaction chamber 4, a heating system, a cooling system and an air outlet system; the air intake system, the preheating system 3, the reaction chamber 4 and the air outlet system are connected in sequence.

[0036] The air intake system includes an air intake pipeline 1 and a gas flow regulating valve 2, which are used to regulate and transport VOCs gas into the reaction device;

[0037] The VOCs gas flow rate is controlled at 1-10m 3 / h range.

[0038] The preheating system 3 is arranged on the air inlet pipe 1 and is used to preheat the VOCs gas entering the reaction device to reach the starting temperature range required for the reaction;

[0039] The preheating temperature is controlled within the range of 180-300°C.

[0040] The reaction chamber 4 is filled with at least two porous medium catalyst layers, and the VOCs gas reacts with oxygen in the reaction chamber 4 under the action of the porous medium catalyst to undergo catalytic oxidation reaction;

[0041] A plurality of temperature sensors 6 are arranged on the wall of the reaction chamber 4 for real-time monitoring of the temperature at different positions in the reaction chamber 4 .

[0042] The porous medium catalyst layers are arranged in series, and the porosity increases continuously along the VOCs gas flow direction;

[0043] The porosity of the porous medium catalyst layer is in the range of 0.3 to 0.8.

[0044] The porous medium catalyst is a supported noble metal catalyst, a transition metal oxide catalyst and a composite oxide catalyst.

[0045] The heating system is arranged around the reaction chamber 4 and includes a plurality of heating units 7, each of which is connected to a temperature controller 8;

[0046] The temperature controller 8 controls the power of the corresponding heating unit 7 according to the temperature information fed back by the temperature sensor 6 , thereby realizing active and precise control of the temperature in the reaction chamber 4 .

[0047] The cooling system is connected to the reaction chamber 4, and includes a cooling pipe 9 and a cooling medium circulation pump 10; when the temperature in the reaction chamber 4 is too high, the cooling system starts to take away excess heat through cooling medium water or air to prevent the catalyst from overheating and deactivation.

[0048] The gas outlet system includes a gas outlet pipeline 11 and a gas purification device 12, which are used to discharge the purified gas after the reaction from the reaction device and further purify the discharged gas to ensure that it meets the emission standards;

[0049] The gas purification device 12 is an activated carbon adsorption device.

[0050] According to another aspect of the present invention, a method for treating VOCs is provided. The method is implemented using the treatment device described in any aspect of the above technical solution, and the method comprises the following steps:

[0051] Step 1: VOCs gas of a certain concentration enters the preheating system 3 through the air intake system and is preheated to a reaction starting temperature of 180-300°C;

[0052] Step 2: The preheated gas enters the reaction chamber 4 and undergoes a catalytic oxidation reaction with oxygen under the action of the porous medium catalyst. During the reaction, the temperature sensor 6 in the reaction chamber 4 monitors the temperature in real time and transmits the temperature information to the temperature controller 8;

[0053] Step 3: The temperature controller 8 compares the received temperature information with the preset optimal reaction temperature range. If the temperature is lower than the optimal reaction temperature range, the temperature controller 8 increases the power of the corresponding heating unit 7 to increase the temperature in the reaction chamber 4; if the temperature is higher than the optimal reaction temperature range, the cooling system is started to reduce the temperature in the reaction chamber 4 so that the reaction is always carried out within the optimal temperature range.

[0054] Step 4: The purified gas after the reaction is discharged from the reaction device through the gas outlet system, and is further processed by the gas purification device 12 to meet the emission standards.

[0055] Furthermore, in step 1, the concentration of the VOCs gas is 2000-10000 mg / m 3 ;

[0056] In step 2, the residence time of the VOCs gas in the reaction chamber 4 is 0.75 to 2 seconds;

[0057] In step three, the temperature fluctuation of the porous medium catalyst layer in the reaction chamber 4 is ±10° C., and the temperature control response time is ≤0.5 s.

[0058] Embodiment 1:

[0059] like Figure 1 As shown, this embodiment provides a VOCs porous medium catalytic oxidation device with active and precise temperature control, including an interconnected air intake pipe 1, a gas flow regulating valve 2, a preheating system 3, a reaction chamber 4, a porous medium catalyst 5, a temperature sensor 6, a heating unit 7, a temperature controller 8, a cooling pipe 9, a cooling medium circulation pump 10, an air outlet pipe 11 and a gas purification device 12.

[0060] In this embodiment, the VOCs gas flow rate is controlled by the gas flow regulating valve 2 to be 5m 3 / h.

[0061] In this embodiment, the VOCs gas temperature is heated to 250°C by the preheating system 3.

[0062] like Figure 2 As shown, the reaction chamber 4 is filled with two layers of porous medium catalyst 5, the porosity increases along the VOCs gas flow direction, the upper layer porosity is 0.4, and the lower layer porosity is 0.7. The catalysts used are all supported precious metal catalysts with activated alumina as the carrier and precious metal palladium as the active ingredient.

[0063] The cooling medium of the cooling system in this embodiment is water.

[0064] According to another aspect of the present invention, this embodiment further provides a method for treating VOCs, which is implemented using a treatment device in any aspect of the above technical solution, and the treatment method comprises the following steps:

[0065] Step 1: Initial concentration is 4000 mg / m 3 The VOCs gas enters the preheating system 3 through the air inlet pipe 1 and is preheated to the reaction starting temperature of 250°C;

[0066] Step 2: The preheated gas enters the reaction chamber 4 and undergoes a catalytic oxidation reaction with oxygen under the action of the porous medium catalyst 5. During the reaction, the temperature sensor 6 in the reaction chamber 4 monitors the temperature in real time and transmits the temperature information to the temperature controller 8;

[0067] Step 3: The temperature controller 8 compares the received temperature information with the preset optimal reaction temperature range. If the temperature is lower than the optimal reaction temperature range, the temperature controller 8 increases the power of the corresponding heating unit 7 to increase the temperature in the reaction chamber 4; if the temperature is higher than the optimal reaction temperature range, the cooling system is started to reduce the temperature in the reaction chamber 4 so that the reaction is always carried out within the optimal temperature range.

[0068] Step 4: The purified gas after the reaction is discharged from the reaction device through the gas outlet system, and is further processed by the gas purification device 12 to meet the emission standards.

[0069] In this embodiment, VOCs gas is passed into the catalytic oxidation device and operated continuously for one hour. Gas samples at the outlet are collected every ten minutes to detect the VOCs concentration. It is found that the average removal rate is 83%, and the removal rate of the whole process is relatively stable. By statistically analyzing the temperature data of the catalyst bed recorded by the temperature sensor 6, it is found that the temperature fluctuation is controlled within ±8°C and the heat distribution is relatively uniform. At the same time, the porous catalyst is analyzed after the operation of the device, and it is found that the activity of 13% of the catalyst surface has decreased and failed to fully participate in the reaction.

[0070] Embodiment 2:

[0071] This embodiment provides a VOCs porous medium catalytic oxidation device and method with active and precise temperature control. The difference from Embodiment 1 is that the reaction chamber 4 is filled with three layers of porous medium catalyst 5, such as Figure 3 As shown, the porosity increases continuously along the VOCs airflow direction, the porosity of the upper layer is 0.4, the porosity of the middle layer is 0.55, and the porosity of the lower layer is 0.7. The rest is exactly the same as in Example 1.

[0072] In this embodiment, VOCs gas is passed into the catalytic oxidation device and operated continuously for one hour. Gas samples at the outlet are collected every ten minutes to detect the VOCs concentration. It is found that the average removal rate is 92%, and the removal rate of the entire process is more stable than that of Example 1. By statistically analyzing the temperature data of the catalyst bed recorded by the temperature sensor 6, it is found that the temperature fluctuation is controlled within ±5°C, and the heat distribution is more uniform than that of Example 1. At the same time, the porous catalyst is analyzed after the operation of the device, and it is found that only 6% of the catalyst surface activity decreases and fails to fully participate in the reaction.

[0073] Comparative Example 1:

[0074] This comparative example provides a VOCs porous medium catalytic oxidation device and method with active and precise temperature control. The difference from Example 1 is that the reaction chamber 4 is filled with only one layer of porous medium catalyst 5. Figure 4 As shown, the porosity is 0.4, and the rest is exactly the same as Example 1.

[0075] In this comparative example, VOCs gas was passed into the catalytic oxidation device and operated continuously for one hour. Gas samples at the outlet were collected every ten minutes to detect the VOCs concentration. It was found that the average removal rate was only 75%, and the removal rate continued to decline in the later stage of operation. By statistically analyzing the temperature data of the catalyst bed recorded by the temperature sensor 6, it was found that the temperature fluctuation was controlled at ±20°C, and there were obvious local overheating or overcooling areas. At the same time, the porous catalyst was analyzed after the operation of the device, and it was found that the activity of 20% of the catalyst surface decreased and failed to fully participate in the reaction.

[0076] It can be seen from the results of the above-mentioned Examples 1 and 2 and Comparative Example 1 that the VOCs porous medium catalytic oxidation device and method with active and precise temperature control described in the present invention, through the compact arrangement of multiple layers of porous medium catalysts 5 with different pore sizes, enhances the internal heat storage and thermal conductivity while increasing the contact area and time between the surface and volatile organic compounds, thereby increasing the utilization rate of the catalyst and improving the purification efficiency; the heating and cooling systems work together to avoid local overheating or overcooling, extend the service life of the catalyst, and reduce energy consumption and costs.

Claims

1. A VOCs porous media catalytic oxidation device with active and precise temperature control, characterized in that: It includes an air intake system, a preheating system, a reaction chamber, a heating system, a cooling system and an air outlet system which are interconnected; The air intake system comprises an air intake pipeline (1) for regulating and transporting VOCs gas into the reaction device and a gas flow regulating valve (2) installed on the air intake pipeline (1); A reaction chamber (4) is arranged at the other end of the air intake pipe (1), the interior of the reaction chamber (4) is filled with at least two porous medium catalyst layers, and porous medium catalysts (5) are arranged in the at least two porous medium catalyst layers; a plurality of temperature sensors (6) are also arranged on the wall surface of the reaction chamber (4); The VOCs gas flow rate is controlled at 1-10 m 3 / h range.

2. According to claim 1, a VOCs porous medium catalytic oxidation device with active and precise temperature control is characterized in that: The porous catalyst layers are arranged in series, and the porosity increases along the VOCs gas flow direction; The porosity of the porous medium catalyst layer is in the range of 0.3 to 0.8; The porous catalyst (5) is a supported noble metal catalyst, a transition metal oxide catalyst and a composite oxide catalyst.

3. The VOCs porous medium catalytic oxidation device with active and precise temperature control according to claim 1 is characterized in that: A heating system is provided on the periphery of the reaction chamber (4). The heating system comprises a plurality of heating units (7) and a temperature controller (8), each of the heating units (7) is connected to a temperature controller (8), and the temperature controller (8) is also connected to a temperature sensor (6).

4. The VOCs porous medium catalytic oxidation device with active and precise temperature control according to claim 1 is characterized in that: A cooling system is also installed in the reaction chamber (4), the cooling system comprising a cooling pipe (9) and a cooling medium circulation pump (10) installed on the cooling pipe (9); The cooling medium in the cooling system is water or air.

5. The VOCs porous medium catalytic oxidation device with active and precise temperature control according to claim 1 is characterized in that: A gas outlet system is also installed at the other end of the reaction chamber (4). The gas outlet system comprises a gas outlet pipeline (11) connected to the reaction chamber (4) and a gas purification device (12) connected to the gas outlet pipeline (11); The gas purification device (12) is an activated carbon adsorption device.

6. The VOCs porous medium catalytic oxidation device with active and precise temperature control according to claim 1 is characterized in that: A preheating system (3) for preheating the VOCs gas entering the reaction device is installed on the air inlet pipeline (1) and between the gas flow regulating valve (2) and the reaction chamber (4); The preheating temperature is controlled within the range of 180-300°C.

7. A method for treating VOCs in a porous medium catalytic oxidation device with active and precise temperature control according to any one of claims 1 to 6, characterized in that: Step 1: VOCs gas enters the preheating system (3) through the air intake system and is preheated to a reaction starting temperature of 180-300°C; Step 2: The preheated gas enters the reaction chamber (4) and undergoes a catalytic oxidation reaction with oxygen under the action of the porous medium catalyst (5). During the reaction, a temperature sensor (6) in the reaction chamber (4) monitors the temperature in real time and transmits the temperature information to a temperature controller (8); Step 3: The temperature controller (8) compares the received temperature information with a preset optimal reaction temperature range. If the temperature is lower than the optimal reaction temperature range, the temperature controller (8) increases the power of the corresponding heating unit (7) to increase the temperature in the reaction chamber (4); if the temperature is higher than the optimal reaction temperature range, the cooling system is activated to reduce the temperature in the reaction chamber (4) so ​​that the reaction is always carried out within the optimal temperature range. Step 4: The purified gas after the reaction is discharged from the reaction device through the gas outlet system, and is further treated by the gas purification device (12) before being discharged in compliance with the emission standards.

8. The method for treating VOCs in a porous medium catalytic oxidation device with active and precise temperature control according to claim 7, characterized in that: In step 1, the concentration of the VOCs gas is 2000-10000 mg / m 3 .

9. According to the method for treating VOCs with an active and precise temperature control porous medium catalytic oxidation device as described in claim 7, in step 2, the residence time of the VOCs gas in the reaction chamber (4) is 0.75 to 2 seconds.

10. The method for treating VOCs in a porous medium catalytic oxidation device with active and precise temperature control according to claim 7, characterized in that: In step three, the temperature fluctuation of the porous medium catalyst layer in the reaction chamber (4) is ±10° C., and the temperature control response time is ≤0.5 s.

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