A waste heat utilization type zeolite rotor catalytic oxidation VOCs treatment system and method

Abstract

The present invention proposes a waste heat utilization type zeolite rotor catalytic oxidation VOCs treatment system and method, the system includes an adsorption system, a desorption system, and a heat recovery system, the adsorption system includes an adsorption zone of a zeolite rotor, an adsorption fan, and an exhaust pipe arranged in sequence along the direction of waste gas treatment, the desorption system includes a cooling zone of a zeolite rotor, a desorption zone of a zeolite rotor, a desorption fan, a catalytic combustion furnace, and an exhaust pipe arranged in sequence along the direction of waste gas treatment, the heat recovery system includes a heat exchanger and an absorption refrigerator, the outlet of the catalytic combustion furnace is connected to the heat exchanger and the absorption refrigerator in sequence and then connected to the exhaust pipe, the absorption refrigerator is connected to the air inlet of the adsorption zone and the cooling zone of the zeolite rotor, and the waste heat of the waste gas is used to cool the inlet waste gas of the zeolite rotor. By using waste heat refrigeration technology, the problem of excessively high inlet waste gas temperature in the adsorption zone of the zeolite rotor is solved with low energy consumption, and the adsorption process is strengthened.

Description

[Technical field]

[0001] The present invention relates to the technical field of volatile organic waste gas treatment, and in particular to a waste heat utilization type zeolite rotor catalytic oxidation VOCs treatment system and method. [Background technology]

[0002] Zeolite wheel-catalytic oxidation technology is a common VOCs treatment technology with stable operation and high purification efficiency. It is widely used under the situation of increasingly stringent domestic VOCs emission standards. The zeolite wheel mainly includes adsorption zone, desorption zone and cooling zone. The exhaust gas is purified through the adsorption zone, and the organic waste gas is concentrated on the zeolite wheel; at the same time, the desorption zone is desorbed and regenerated after being heated by another exhaust gas. The desorption temperature is between 180-220℃. After desorption, the high-concentration VOCs exhaust gas is purified in the next step, and the high-temperature desorption zone continues to perform adsorption operations. Zeolite materials have the physical properties of low-temperature adsorption and high-temperature desorption. If the bed temperature is too high, normal adsorption operations cannot be performed. Therefore, a cooling zone is added to cool the high-temperature desorption zone before the adsorption operation.

[0003] In actual operation, the cooling zone uses normal temperature exhaust gas for air cooling, and the air volume is the same as that of the desorption zone, which cannot effectively cool the high-temperature bed to normal temperature. This will cause the bed in the cooling zone to still have a certain temperature when entering the adsorption zone. After the exhaust gas passes through the adsorption zone, the temperature will rise by 3-5°C, and the high adsorption temperature will lead to a decrease in adsorption. In order to strengthen the VOCs adsorption process, lowering the exhaust gas inlet temperature is an effective way. A waste heat utilization type zeolite rotor catalytic oxidation VOCs treatment system and method are proposed. [Summary of the invention]

[0004] The purpose of the present invention is to solve the problems in the prior art and to propose a waste heat utilization type zeolite rotor catalytic oxidation VOCs treatment system and method, which uses waste heat refrigeration technology to solve the problem of excessively high inlet exhaust gas temperature in the zeolite rotor adsorption zone with low energy consumption and enhance the adsorption process.

[0005] To achieve the above-mentioned objectives, the present invention proposes a waste heat utilization type zeolite rotor catalytic oxidation VOCs treatment system including an adsorption system, a desorption system, and a heat recovery system. The adsorption system includes an adsorption zone, an adsorption fan, and an exhaust pipe of a zeolite rotor arranged in sequence along the exhaust gas treatment direction. The desorption system includes a cooling zone, a desorption zone, a zeolite rotor, a desorption fan, a catalytic combustion furnace, and an exhaust pipe arranged in sequence along the exhaust gas treatment direction. The heat recovery system includes a heat exchanger and an absorption refrigerator. The outlet of the catalytic combustion furnace is connected to the heat exchanger and the absorption refrigerator in sequence and then connected to the exhaust pipe. The absorption refrigerator is connected to the air inlets of the adsorption zone and the cooling zone of the zeolite rotor to cool the inlet exhaust gas of the zeolite rotor by utilizing the waste heat of the exhaust gas.

[0006] Preferably, the heat exchanger includes a first heat exchanger and a second heat exchanger, and the outlet of the catalytic combustion furnace is connected to the first heat exchanger, the second heat exchanger, and the absorption refrigerator in sequence, and then connected to the exhaust pipe.

[0007] Preferably, the outlet of the cooling zone of the zeolite wheel is connected to the first heat exchanger and then connected to the inlet of the desorption zone of the zeolite wheel. The first heat exchanger uses the hot exhaust gas at the outlet of the catalytic combustion furnace to heat the exhaust gas at the inlet of the desorption zone.

[0008] Preferably, the outlet of the desorption fan is connected to the second heat exchanger and then connected to the inlet of the catalytic combustion furnace. The second heat exchanger uses the residual heat exhaust gas at the outlet of the catalytic combustion furnace that has been initially cooled by the first heat exchanger to preheat the exhaust gas at the inlet of the catalytic combustion furnace. The second heat exchanger also includes a cold flow bypass for adjusting the temperature of the exhaust gas at its hot flow outlet.

[0009] Preferably, a heating zone and a catalytic zone are sequentially arranged inside the catalytic combustion furnace along the exhaust gas treatment direction, the inlet of the heating zone is connected to the outlet of the desorption fan, the outlet of the heating zone is connected to the inlet of the catalytic zone, and the outlet of the catalytic zone is connected to the inlet of the heat exchanger.

[0010] The present invention also proposes a waste heat utilization type zeolite rotor catalytic oxidation VOCs treatment method, which specifically includes the following steps:

[0011] S1. Adsorption step: After the exhaust gas passes through the absorption refrigerator, the temperature is reduced, and then it enters the zeolite wheel adsorption zone to complete the adsorption purification, and is pulled to the exhaust pipe by the adsorption fan for discharge; the organic molecules are concentrated in the zeolite wheel adsorption zone;

[0012] S2. Desorption step: part of the exhaust gas enters the cooling zone of the zeolite wheel for preheating, and then is heated to 180-220°C through the first heat exchanger, and the desorption zone of the zeolite wheel is desorbed. At this time, the exhaust gas is enriched with high-concentration VOCs; the cooling zone of the zeolite wheel is cooled, and then enters the adsorption zone for adsorption; after the desorption of the desorption zone of the zeolite wheel is completed, it enters the cooling zone for cooling; the exhaust gas is pressurized and transported by the desorption fan, and after being preheated by the second heat exchanger, it enters the catalytic combustion furnace, first heated to the catalytic combustion reaction working temperature through the heating zone, and then passed into the catalytic zone to complete the catalytic combustion reaction, the exhaust gas is purified, and the tail gas enters the exhaust pipe after the waste heat is utilized by the first heat exchanger, the second heat exchanger, and the absorption refrigerator;

[0013] S3. Heat recovery step: The room temperature exhaust gas is preheated by passing through the cooling zone of the zeolite wheel.

[0014] Preferably, the heat recovery step further comprises using a first heat exchanger to heat the exhaust gas at the inlet of the zeolite wheel desorption zone using the hot exhaust gas at the outlet of the catalytic combustion furnace.

[0015] Preferably, the heat recovery step also includes a second heat exchanger that can use the waste heat exhaust gas at the outlet of the catalytic combustion furnace that has been initially cooled by the first heat exchanger to preheat the exhaust gas at the inlet of the catalytic combustion furnace.

[0016] Preferably, the heat recovery step also includes an absorption refrigerator using the waste heat exhaust gas at the outlet of the catalytic combustion furnace after being cooled by the first heat exchanger and the second heat exchanger to cool the exhaust gas at the inlet of the zeolite wheel, and the heat is absorbed by the first cooling water pipeline and the second cooling water pipeline in the absorption refrigerator.

[0017] Preferably, when the temperature of the waste heat exhaust gas after being cooled by the first heat exchanger and the second heat exchanger is lower than a certain value, the exhaust gas temperature at the hot flow outlet of the second heat exchanger is adjusted by increasing the cold flow bypass flow of the second heat exchanger.

[0018] Beneficial effects of the present invention:

[0019] 1. Lowering the temperature of the exhaust gas inlet of the zeolite wheel adsorption can increase the zeolite adsorption capacity, reduce the adverse effect of residual heat in the cooling zone of the zeolite wheel on adsorption, strengthen the adsorption process, and increase the VOCs purification efficiency.

[0020] 2. The first heat exchanger and the second heat exchanger use the hot exhaust gas from the catalytic combustion furnace to heat the zeolite wheel desorption airflow and the catalytic combustion furnace inlet airflow respectively, so as to realize the rational use of waste heat and exhaust gas resources.

[0021] 3. This method has low operating energy consumption to achieve the low-temperature adsorption target.

[0022] The features and advantages of the present invention will be described in detail through embodiments in conjunction with the accompanying drawings.

Brief Description of the Drawings

[0023] Figure 1 This is a schematic diagram of the structure of a waste heat utilization type zeolite rotor catalytic oxidation VOCs treatment system of the present invention;

[0024] Figure 2 This is a schematic diagram of a zeolite wheel, used to illustrate the operation of the zeolite wheel.

[0025] Description of reference numerals:

[0026] 1-zeolite wheel, 101-adsorption zone, 102-cooling zone, 103-desorption zone, 2-adsorption fan, 3-exhaust pipe, 4-desorption fan, 5-catalytic combustion furnace, 501-catalytic zone, 502-heating zone, 6-first heat exchanger, 7-second heat exchanger, 701-cold flow bypass, 8-absorption refrigerator, 801-first cooling water pipeline, 802-second cooling water pipeline. [Specific implementation method]

[0027] See also Figure 1 to Figure 2The present invention discloses a waste heat utilization type zeolite rotor catalytic oxidation VOCs treatment system, comprising an adsorption system, a desorption system, and a heat recovery system. The adsorption system comprises an adsorption zone 101, an adsorption fan 2, and an exhaust pipe 3 of a zeolite rotor 1 which are sequentially arranged along the exhaust gas treatment direction. The desorption system comprises a cooling zone 102, a desorption zone 103, a desorption fan 4, a catalytic combustion furnace 5, and an exhaust pipe 3 of the zeolite rotor 1 which are sequentially arranged along the exhaust gas treatment direction. The heat recovery system comprises a heat exchanger and an absorption refrigerator 8. The outlet of the catalytic combustion furnace 5 is sequentially connected to the heat exchanger and the absorption refrigerator 8 and then connected to the exhaust pipe 3. The absorption refrigerator 8 is connected to the air inlets of the adsorption zone 101 and the cooling zone 102 of the zeolite rotor 1, and the inlet exhaust gas of the zeolite rotor 1 is cooled by utilizing the waste heat of the exhaust gas.

[0028] Furthermore, the heat exchanger includes a first heat exchanger 6 and a second heat exchanger 7 , and the outlet of the catalytic combustion furnace 5 is sequentially connected to the first heat exchanger 6 , the second heat exchanger 7 , and the absorption refrigerator 8 , and then connected to the exhaust pipe 3 .

[0029] Furthermore, the outlet of the cooling zone 102 of the zeolite rotor 1 is connected to the first heat exchanger 6 and then connected to the inlet of the desorption zone 103 of the zeolite rotor 1 . The first heat exchanger 6 uses the hot exhaust gas at the outlet of the catalytic combustion furnace 5 to heat the exhaust gas at the inlet of the desorption zone 103 .

[0030] Furthermore, the outlet of the desorption fan 4 is connected to the second heat exchanger 7 and then connected to the inlet of the catalytic combustion furnace 5. The second heat exchanger 7 uses the residual heat exhaust gas at the outlet of the catalytic combustion furnace 5 that has been initially cooled by the first heat exchanger 6 to preheat the exhaust gas at the inlet of the catalytic combustion furnace 5. The second heat exchanger 7 also includes a cold flow bypass 701 for adjusting the temperature of the exhaust gas at its hot flow outlet.

[0031] Furthermore, a heating zone 502 and a catalytic zone 501 are sequentially arranged inside the catalytic combustion furnace 5 along the exhaust gas treatment direction, the inlet of the heating zone 502 is connected to the outlet of the desorption fan 4, the outlet of the heating zone 502 is connected to the inlet of the catalytic zone 501, and the outlet of the catalytic zone 501 is connected to the inlet of the heat exchanger.

[0032] The system uses the exhaust heat of the zeolite wheel-catalytic combustion system to cool the exhaust gas concentration at the inlet of the zeolite wheel adsorption zone by adding an absorption refrigerator, strengthening the adsorption process, and achieving the purpose of increasing purification efficiency with low operating energy consumption. The specific implementation method is as follows:

[0033] See also Figure 1 The system includes three modules: adsorption system, desorption system and heat recovery system. After the VOCs waste gas to be treated is dusted and dehumidified in advance, it enters the adsorption system and desorption system respectively according to the concentration ratio of the zeolite wheel 1.

[0034] See also Figure 2 The core equipment of the process is the zeolite wheel 1, which consists of an adsorption zone 101, a cooling zone 102, and a desorption zone 103. The working module (wheel) of the zeolite wheel 1 rotates unidirectionally, so that the same sector area passes through the adsorption zone 101, the desorption zone 103, and the cooling zone 102 in sequence, and undergoes three processes of normal temperature adsorption concentration, high temperature desorption regeneration, and high temperature cooling to normal temperature, completing the adsorption-desorption regeneration process.

[0035] The present invention provides a waste heat utilization type zeolite wheel catalytic oxidation VOCs treatment method, which specifically comprises the following steps:

[0036] S1. The operation mode of the adsorption system is as follows: after the exhaust gas passes through the absorption refrigerator 8, the temperature is reduced, and then it enters the adsorption zone 101 of the zeolite wheel 1 to complete the adsorption purification, and is pulled by the adsorption fan 2 to be discharged to the exhaust pipe 3; the organic molecules are concentrated in the adsorption zone 101 of the zeolite wheel 1.

[0037] S2. The operation mode of the desorption system is as follows: the exhaust gas enters the cooling zone 102 of the zeolite rotor 1 for preheating, and then is heated to 180-220°C through the first heat exchanger 6, and the desorption zone 103 of the zeolite rotor 1 is desorbed. At this time, the exhaust gas is enriched with high-concentration VOCs; the cooling zone 102 of the zeolite rotor 1 is cooled, and waits to enter the adsorption zone 101 for adsorption; after the desorption in the desorption zone 103 of the zeolite rotor 1 is completed, it waits to enter the cooling zone 102 for cooling; then the exhaust gas is pressurized and transported by the desorption fan 4, and after being preheated by the second heat exchanger 7, it enters the catalytic combustion furnace 5, firstly heated to the catalytic combustion reaction working temperature (generally above 260°C) through the heating zone 502, and then passed into the catalytic zone 501 to complete the catalytic combustion reaction, the exhaust gas is purified, and the tail gas enters the exhaust pipe 3 for discharge after the waste heat is utilized by the first heat exchanger 6, the second heat exchanger 7, and the absorption refrigerator 8;

[0038] S3. The heat recovery system operates as follows: the normal temperature exhaust gas is preheated through the cooling zone 102 of the zeolite wheel 1.

[0039] Furthermore, the operation mode of the heat recovery system in step S3 also includes: the first heat exchanger 6 utilizes the hot exhaust gas at the outlet of the catalytic combustion furnace 5 to heat the exhaust gas at the inlet of the desorption zone 103 of the zeolite wheel 1 .

[0040] Furthermore, the operation mode of the heat recovery system in step S3 also includes: the second heat exchanger 7 uses the waste heat exhaust gas at the outlet of the catalytic combustion furnace 5 that has been preliminarily cooled by the first heat exchanger 6 to preheat the exhaust gas at the inlet of the catalytic combustion furnace 5 .

[0041] Furthermore, the operation mode of the heat recovery system in step S3 also includes: the absorption refrigerator 8 is usually a lithium bromide absorption refrigerator, and the waste heat exhaust gas at the outlet of the catalytic combustion furnace 5 is cooled to 100-180°C through the first heat exchanger 6 and the second heat exchanger 7 to cool the waste gas inlet of the zeolite wheel 1. The heat is absorbed by the cooling water in the first cooling water pipeline 801 and the second cooling water pipeline 802. If the waste heat exhaust temperature is too low, it can be adjusted by increasing the flow rate of the cold flow bypass 701 of the second heat exchanger 7.

[0042] The above embodiments are intended to illustrate the present invention, not to limit the present invention. Any solution that is a simple transformation of the present invention belongs to the protection scope of the present invention.

Claims

1. A waste heat utilization type zeolite rotor catalytic oxidation VOCs treatment system, characterized by: The invention comprises an adsorption system, a desorption system and a heat recovery system. The adsorption system comprises an adsorption zone (101) of a zeolite rotor (1), an adsorption fan (2) and an exhaust pipe (3) arranged in sequence along the direction of waste gas treatment. The desorption system comprises a cooling zone (102) of the zeolite rotor (1), a desorption zone (103) of the zeolite rotor (1), a desorption fan (4), a catalytic combustion furnace (5) and an exhaust pipe (3) arranged in sequence along the direction of waste gas treatment. The heat recovery system comprises a heat exchanger and an absorption refrigerator (8). The outlet of the catalytic combustion furnace (5) is connected to the heat exchanger and the absorption refrigerator (8) in sequence and then connected to the exhaust pipe (3). The absorption refrigerator (8) is connected to the air inlets of the adsorption zone (101) and the cooling zone (102) of the zeolite rotor (1) to cool the inlet waste gas of the zeolite rotor (1) by using the waste heat of the waste gas. The heat exchanger comprises a first heat exchanger (6) and a second heat exchanger (7). The catalytic combustion furnace (5) is connected to the exhaust pipe (3). The outlet of the catalytic combustion furnace (5) is connected to the first heat exchanger (6), the second heat exchanger (7), and the absorption refrigerator (8) in sequence, and then connected to the exhaust pipe (3). The interior of the catalytic combustion furnace (5) is provided with a heating zone (502) and a catalytic zone (501) in sequence along the exhaust gas treatment direction. The inlet of the heating zone (502) is connected to the outlet of the desorption fan (4), the outlet of the heating zone (502) is connected to the inlet of the catalytic zone (501), the outlet of the catalytic zone (501) is connected to the inlet of the heat exchanger, the outlet of the desorption fan (4) is connected to the second heat exchanger (7), and then connected to the inlet of the catalytic combustion furnace (5). The second heat exchanger (7) uses the residual heat exhaust gas at the outlet of the catalytic combustion furnace (5) after preliminary cooling by the first heat exchanger (6) to preheat the exhaust gas at the inlet of the catalytic combustion furnace (5). The second heat exchanger (7) also includes a cold flow bypass (701) for adjusting the temperature of the exhaust gas at its hot flow outlet.

2. A waste heat utilization type zeolite rotor catalytic oxidation VOCs treatment system as claimed in claim 1, characterized in that: The outlet of the cooling zone (102) of the zeolite rotor (1) is connected to the first heat exchanger (6), and then connected to the inlet of the desorption zone (103) of the zeolite rotor (1). The first heat exchanger (6) uses the hot exhaust gas at the outlet of the catalytic combustion furnace (5) to heat the exhaust gas at the inlet of the desorption zone (103).

3. A waste heat utilization type zeolite rotor catalytic oxidation VOCs treatment method, characterized by: The specific steps include: S1. Adsorption step: After the exhaust gas passes through the absorption refrigerator (8), the temperature is reduced, and then the exhaust gas enters the adsorption zone (101) of the zeolite wheel (1), completes the adsorption purification, and is drawn to the exhaust pipe (3) by the adsorption fan (2) for discharge; the organic molecules are concentrated in the adsorption zone (101) of the zeolite wheel (1); S2. Desorption step: a portion of the exhaust gas enters the cooling zone (102) of the zeolite rotor (1) for preheating, and then is heated to 180-220°C by the first heat exchanger (6), and desorbs the exhaust gas in the desorption zone (103) of the zeolite rotor (1). At this time, the exhaust gas is enriched with high-concentration VOCs; the cooling zone (102) of the zeolite rotor (1) is cooled and enters the adsorption zone (101) for adsorption; after the desorption in the desorption zone (103) of the zeolite rotor (1) is completed, The exhaust gas is then transported through the desorption fan (4) under pressure, and after being preheated by the second heat exchanger (7), it enters the catalytic combustion furnace (5), is first heated to the working temperature of the catalytic combustion reaction by the heating zone (502), and then enters the catalytic zone (501) to complete the catalytic combustion reaction. The exhaust gas is purified, and the tail gas is discharged into the exhaust pipe (3) after the waste heat is utilized by the first heat exchanger (6), the second heat exchanger (7), and the absorption refrigerator (8); S3. Heat recovery step: The room temperature exhaust gas is preheated by passing through the cooling zone (102) of the zeolite wheel (1).

4. A waste heat utilization type zeolite rotor catalytic oxidation VOCs treatment method as claimed in claim 3, characterized in that: The heat recovery step also includes a first heat exchanger (6) using the hot exhaust gas at the outlet of the catalytic combustion furnace (5) to heat the exhaust gas at the inlet of the desorption zone (103) of the zeolite wheel (1).

5. A waste heat utilization type zeolite rotor catalytic oxidation VOCs treatment method as claimed in claim 3, characterized in that: The heat recovery step also includes the second heat exchanger (7) being able to use the residual heat exhaust gas at the outlet of the catalytic combustion furnace (5) after preliminary cooling by the first heat exchanger (6) to preheat the exhaust gas at the inlet of the catalytic combustion furnace (5).

6. A waste heat utilization type zeolite rotor catalytic oxidation VOCs treatment method as claimed in claim 3, characterized in that: The heat recovery step also includes the absorption refrigerator (8) using the waste heat exhaust gas at the outlet of the catalytic combustion furnace (5) after being cooled by the first heat exchanger (6) and the second heat exchanger (7) to cool the exhaust gas at the inlet of the zeolite wheel (1), and the heat is absorbed by the first cooling water pipeline (801) and the second cooling water pipeline (802) in the absorption refrigerator (8).

7. A waste heat utilization type zeolite rotor catalytic oxidation VOCs treatment method as claimed in claim 6, characterized in that: When the temperature of the waste heat exhaust gas after being cooled by the first heat exchanger (6) and the second heat exchanger (7) is lower than a certain value, the exhaust gas temperature at the hot flow outlet of the second heat exchanger (7) is adjusted by increasing the flow rate of the cold flow bypass (701) of the second heat exchanger (7).

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