A paint spraying organic waste gas adsorption concentration high temperature desorption catalytic combustion device and process

Abstract

The present invention discloses a paint spray organic waste gas (VOCs) adsorption concentration high temperature desorption catalytic combustion treatment device and its process, comprising a filter 1, a plurality of parallel activated carbon adsorption boxes 301, an induced draft fan 5, a heat exchanger 19, a flame arrester filter 9, a desorption circulation method 10, a desorption fan 11, a catalytic combustion bed 12, an exhaust pipe 6, an oxygen supply air valve 20, a cooling and emptying valve 14 and a cold supply air valve 18. The present invention adds a heat exchanger between the induced draft fan 5 and the exhaust pipe 6, effectively reduces the desorption gas temperature under low oxygen conditions, improves safety and desorption efficiency; by setting a cooling pipeline, the induced draft fan only cools the activated carbon, reduces the operating time of the circulating fan and the energy consumption of the catalytic heating bed reheating, and saves energy and protects the environment; and by installing a high temperature alarm system, nitrogen cooling II and a water spray pipeline III, effectively curbs the occurrence of activated carbon fire accidents.

Description

Technical Field

[0001] The invention relates to the technical field of waste gas treatment, and in particular to an activated carbon adsorption, high temperature desorption and catalytic combustion treatment device for volatile organic waste gas (VOCs) waste gas of a paint spraying production line. Background Art

[0002] A large number of spraying industries are concentrated in the Beijing-Tianjin-Hebei, Yangtze River Delta, and Pearl River Delta regions of my country. Spraying companies generate a large amount of VOCs waste gas and have many problems, which are in urgent need of rectification. The VOCs composition in spraying waste gas is relatively complex and varies greatly. For example, alkyd resin paints use solvents such as solvent oil, xylene, and toluene. Epoxy resin paints mainly contain toluene, xylene, butanol and other solvents. Polyurethane paints use cyclohexane, toluene, ethyl acetate, xylene and other solvents. During the painting process, a large amount of organic solvents originally in the paint volatilize, which not only has a special irritating odor, but also has a serious impact on the health of spray painters and surrounding residents. At the same time, a large amount of dust and paint mist will also be generated during the planing and spraying process.

[0003] How to meet green environmental protection requirements and effectively treat VOCs waste gas is an important issue at present. Due to the complexity of VOCs components in paint exhaust gas, several combined processes are usually required for treatment. For large air volume and low concentration VOCs waste gas, a combined treatment process of activated carbon adsorption concentration, high temperature desorption, and catalytic combustion can not only continuously treat VOCs waste gas and convert it into harmless water and carbon dioxide, but also use the heat released by catalytic combustion to desorb and regenerate the adsorption saturated activated carbon. The desorbed high concentration VOCs are burned to maintain the catalytic combustion bed stable at a higher temperature, without the need for external heating, to achieve the purpose of waste heat utilization and energy saving and environmental protection.

[0004] However, this process currently still has shortcomings in terms of safety and efficiency. During the desorption process, VOCs are concentrated and sent to the catalytic combustion bed. The gas after catalytic combustion releases a large amount of heat, and its temperature may exceed the set value, endangering the safety of the activated carbon box. The current common treatment process is to supplement the air volume by adding fresh air to achieve the effect of cooling the gas. However, after the air is supplemented, the oxygen content in the desorbed gas increases, and it may come into contact with the internal high-temperature points in the active box to cause a combustion accident. Therefore, the temperature of the desorbed gas is generally set not to exceed 100°C, the desorption time is long, and the efficiency is low.

[0005] In addition, in the current process, after desorption is completed, air is generally supplied by a supplementary cooling fan to cool the pipeline and equipment. Since the circulating fan must be kept on in the necessary pipeline, it is not conducive to saving electricity and extending the service life of the fan. During the cooling process, the catalytic combustion bed drops rapidly due to the large amount of cold air entering and leaving. When the next desorption cycle begins, it needs to be heated again to reach the combustion conditions, resulting in energy waste. Summary of the invention

[0006] The purpose of the present invention is to solve the problems of safety and long activated carbon desorption time in the paint spraying VOCs desorption catalytic combustion process, and to provide an energy-saving adsorption concentration high-temperature desorption catalytic combustion treatment device. The specific technical scheme is as follows:

[0007] A paint spraying organic waste gas adsorption concentration high temperature desorption catalytic combustion treatment device, characterized by: comprising a filter, a plurality of parallel activated carbon adsorption boxes, an induced draft fan, a heat exchanger, a flame arrester filter, a desorption circulation valve, a desorption fan, a catalytic combustion bed, an exhaust pipe, an oxygen supply air valve, a cooling exhaust valve and a cold supply air valve;

[0008] The VOCs waste gas outlet is connected to the filter air inlet through pipe I; the activated carbon adsorption box is provided with a VOCs adsorption inlet, an adsorption purification outlet, a desorption air supply inlet, and a desorption return air outlet. The filter air outlet is connected to the VOCs adsorption inlet of multiple parallel activated carbon adsorption boxes through an air duct, and the adsorption purification outlet of the activated carbon adsorption box is connected to the induced draft fan through an air duct. The exhaust duct is provided with an air valve. The adsorption purification outlet of the activated carbon adsorption box 3, the induced draft fan and the exhaust pipe are connected in sequence through air ducts;

[0009] The air duct connecting the induced draft fan and the exhaust pipe is provided with a heat exchange branch pipe, which is connected to the air inlet of the heat exchanger and is provided with a heat exchange air inlet valve, and the air outlet of the heat exchanger is connected to the exhaust pipe through the air duct; the induced draft fan and the desorption main pipeline are provided with a cooling branch pipe, on which a cold air supplement valve is provided; the desorption return air outlet of the activated carbon adsorption box, the flame arrester filter, the desorption fan, and the catalytic combustion bed are connected in sequence through the air duct, a desorption circulation valve is provided between the flame arrester filter and the desorption fan, an oxygenation air duct is provided between the desorption circulation valve and the desorption fan, and an oxygenation air valve is provided; a cooling air duct is provided between the flame arrester and the exhaust pipe, and a cooling exhaust valve is provided; the catalytic combustion bed is connected to the induced draft fan through the circulation air duct The circulating air inlet of the heat exchanger is connected, the circulating air outlet of the heat exchanger is connected to the desorption main pipeline of the activated carbon adsorption box, a branch pipe is arranged between the catalytic combustion bed and the exhaust pipe, and a combustion exhaust valve is arranged, and the activated carbon desorption main pipeline is connected to the activated carbon desorption air supply inlet through the branch pipes respectively; the catalytic combustion bed is provided with a far-infrared electric heating layer, a catalytic combustion layer, and a heat exchange layer, and the outer wall is provided with a high-temperature resistant rock wool insulation layer; the desorbed gas is maintained at about 120±5℃ during the desorption process; the activated carbon adsorption boxes are all provided with a high-temperature alarm system; a nitrogen pipeline II and a water spray pipeline III are arranged in the device, which are connected to each activated carbon adsorption box, and corresponding air valves or water valves are arranged on each connecting pipeline.

[0010] The filter comprises a primary filter layer, a medium filter layer and an activated carbon sacrificial bed.

[0011] The activated carbon adsorption box is provided with a glass window, and waterproof honeycomb activated carbon is used in the box.

[0012] The adsorption concentration high-temperature desorption catalytic combustion treatment device is equipped with a PLC control system. The induced draft fan, desorption fan, high-temperature alarm system, and infrared heating device of the catalytic combustion bed are all controlled by the PLC system; the air valves and water valves provided on the nitrogen pipeline, water spray pipeline, desorption air duct, adsorption air duct, cooling air duct, and heat exchange air duct are all controlled by the PLC system.

[0013] A paint spraying VOCs waste gas adsorption concentration high temperature desorption catalytic combustion treatment process using the device, characterized in that:

[0014] 1) In the adsorption concentration process, the VOCs waste gas passes through the filter 1 to remove dust and paint mist, and is adsorbed and purified by multiple parallel activated carbon boxes 301 before being discharged from the exhaust pipe 6;

[0015] 2) The device adopts a "multi-absorption and one-desorption" process. An activated carbon adsorption box 3 is always kept in a desorption state in the device. When a certain activated carbon box 3 is saturated with adsorption, its adsorption inlet 2 and outlet valve 4 are closed, and the cooling exhaust valve 14, the cold air valve 18, and the heat exchange inlet valve 17 are ensured to be closed. At the beginning of desorption, the precious metal catalyst inside the catalytic bed 12 is preheated. When the bed reaches a predetermined temperature, the desorption fan 11 and the desorption circulation valve 10, the desorption inlet 7 and the outlet air valve 8 are turned on to switch it to a desorption regeneration state, and intermittent oxygen is supplemented to provide sufficient oxygen for combustion. When supplementing oxygen, the combustion exhaust valve 13 is opened synchronously;

[0016] 3) After desorption is completed, increase the air volume of the heat exchange inlet valve 17 to reduce the temperature of the desorbed gas to below 100°C, close the heat exchange inlet valve 17, open the cooling air valve 18 and the cooling exhaust valve 14, close the desorption fan 11 and the desorption circulation valve 10, and use part of the purified exhaust gas to directly cool the activated carbon box; when cooling is completed, close the cooling air valve 18, the cooling exhaust valve 14, the desorption inlet valve 7 and the desorption outlet valve 8, open the adsorption inlet valve 2 and the adsorption outlet valve 4, and switch the activated carbon adsorption box to the adsorption mode.

[0017] Beneficial Effects

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] (1) The present invention effectively reduces the temperature of the desorbed gas by using a heat exchanger without increasing the oxygen content of the desorbed gas; (2) Since the oxygen content of the desorbed gas is relatively low, safety is increased, and the temperature of the desorbed gas can be increased from 100°C in the traditional process to 120°C, thereby improving the desorption efficiency; (3) Without adding a cooling fan, the present invention utilizes the air volume of the induced draft fan to achieve the cooling process of the desorbed gas, thereby reducing equipment costs and operating expenses; (4) By adding cooling pipes and air valves, during the cooling process after the desorption is completed, the induced draft fan is used to directly cool the activated carbon box to avoid cooling the catalytic combustion bed, thereby reducing the operating time of the desorption fan and the heating energy consumption of the catalytic combustion bed in the next desorption cycle, thereby achieving the purpose of energy saving; (5) By adding nitrogen distribution pipes, water spray pipes and over-temperature alarm systems, accidents of activated carbon ignition caused by excessively high desorbed gas temperatures can be effectively prevented. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of the paint spraying organic waste gas adsorption concentration high-temperature desorption catalytic combustion device provided by the present invention;

[0021] Figure 2 is a schematic diagram of a filter of the present invention;

[0022] Figure 3 is a schematic diagram of a catalytic combustion bed of the present invention;

[0023] In the figure: exhaust gas pipeline I, nitrogen pipeline II, spray water pipeline III, filter 1, adsorption inlet valve 2, activated carbon adsorption box 3, adsorption outlet valve 4, induced draft fan 5, exhaust pipe 6, desorption inlet valve 7, desorption outlet valve 8, flame arrester filter 9, desorption circulation valve 10, desorption fan 11, catalytic combustion bed 12, combustion exhaust valve 13, cooling exhaust valve 14, nitrogen inlet valve 15, spray water valve 16, heat exchange inlet valve 17, cold air valve 18, heat exchanger 19, oxygen supply air valve 20, primary filter layer 101, medium filter layer 102, activated carbon sacrificial layer 103, multiple parallel activated carbon adsorption boxes 301, spare activated carbon adsorption box 302, far infrared heating layer 1201, catalytic combustion layer 1202, heat exchange layer 1201. DETAILED DESCRIPTION

[0024] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments:

[0025] A paint spraying VOCs waste gas adsorption concentration high-temperature desorption catalytic combustion treatment device and its process, including a filter 1, a plurality of parallel activated carbon adsorption boxes 301, an induced draft fan 5, a heat exchanger 19, a flame arrester filter 9, a desorption circulation valve 10, a desorption fan 11, a catalytic combustion bed 12, an exhaust pipe 6, an oxygen supply air valve 20, a cooling exhaust valve 14 and a cold supply air valve 18.

[0026] The VOCs waste gas outlet is connected to the filter air inlet through a pipe I to remove a large amount of dust and paint mist generated during the painting process. The filter adopts a two-stage filtration and an activated carbon sacrificial bed process for pretreatment. The waste gas first passes through the primary filter layer 101 and the medium-efficiency filter 102 to remove the paint mist, and then passes through the primary activated carbon sacrificial bed 103 to remove high-boiling point macromolecular substances and easily polymerizable monomer substances such as acrylic acid. The activated carbon is replaced regularly according to the actual operation situation.

[0027] The activated carbon adsorption box 3 is provided with a VOCs adsorption inlet, an adsorption purification outlet, a desorption air supply inlet, and a desorption return air outlet. The filter outlet is connected to the VOCs adsorption inlets of multiple parallel activated carbon adsorption boxes through an air duct, and the activated carbon adsorption box adsorption purification outlet is connected to the induced draft fan through an air duct. The exhaust duct is provided with an air valve. The adsorption purification outlet of the activated carbon adsorption box 3, the induced draft fan 5 and the exhaust pipe 6 are connected in sequence through an air duct. The properties of the activated carbon itself do not change during the adsorption process, and the adsorption process is reversible, and multiple adsorption and desorption can be performed. The present invention adopts the "multi-absorption and one-desorption" online adsorption and desorption process. When a certain activated carbon box is saturated with adsorption, it is switched to a desorption regeneration state, and the remaining activated carbons are in an adsorption state. In the adsorption and desorption system, a spare activated carbon adsorption box 302 is reserved, which is put into operation when an abnormal situation occurs to prevent production shutdown due to abnormal operation of environmental protection equipment.

[0028] The air duct connecting the induced draft fan 5 to the exhaust pipe is provided with a heat exchange branch pipe, which is connected to the air inlet of the heat exchanger and is provided with a heat exchange air inlet valve 17, and the air outlet of the heat exchanger is connected to the exhaust pipe through the air duct; the induced draft fan 5 and the desorption main pipeline are provided with a cooling branch pipe, on which a cold air supplement valve 18 is provided; the desorption return air outlet of the activated carbon adsorption box 3, the flame arrester filter 9, the desorption fan 11, and the catalytic combustion bed 12 are connected in sequence through the air duct, a desorption circulation valve 10 is provided between the flame arrester filter 9 and the desorption fan 11, an oxygenation air duct is provided between the desorption circulation valve 10 and the desorption fan, and an oxygenation air valve 20 is provided; a cooling air duct is provided between the flame arrester and the exhaust pipe, and a cooling exhaust valve 14 is provided; the catalytic combustion bed 12 is connected through the circulating air The pipe is connected to the circulating air inlet of the heat exchanger 19, and the circulating air outlet of the heat exchanger 19 is connected to the desorption main pipeline of the activated carbon adsorption box. A branch pipe is provided between the catalytic combustion bed 12 and the exhaust pipe, and a combustion exhaust valve 13 is provided. The activated carbon desorption main pipeline is connected to the activated carbon desorption air supply inlet through the branch pipes respectively; the catalytic combustion bed 12 is provided with a far-infrared electric heating layer 1201, a catalytic combustion layer 1202, and a heat exchange layer 1203, and the outer wall is provided with a high-temperature resistant rock wool insulation layer; when a certain activated carbon box is saturated with adsorption, its adsorption air intake 2 and air outlet valve 4 are closed, and the cooling and emptying valve 14, the cold air supplement valve 18, and the heat exchange air intake valve 17 are ensured to be closed, and the precious metal catalyst inside the catalytic bed is preheated at the beginning of desorption, and hot air is generated. When the bed reaches the predetermined temperature, the desorption fan 11 and the desorption circulation valve 10, the desorption air intake 7 and the air outlet valve 8 are turned on to switch it to the desorption regeneration state.

[0029] In the catalytic combustion bed 12, the desorbed gas first enters the heat exchange layer 1203 for preheating, and enters the electric heating layer 1201 to further increase the temperature, and then is discharged through the heat exchange layer after catalytic combustion in the combustion layer 1202, and part of the residual heat is transferred to the desorbed gas entering the combustion bed in the heat exchange layer. The temperature difference between the catalytic combustion layer 1202 and the electric heating layer 1201 is used to determine whether oxygen supplementation is needed. When the temperature difference is lower than the set value, the oxygen supplement air valve 20 is opened to provide sufficient oxygen for catalytic combustion, and the combustion exhaust valve 13 is opened simultaneously to keep the air pressure in the pipeline equipment balanced with the outside world. When the temperature difference value drops to a certain range, the oxygen supplement air valve 20 and the combustion exhaust valve 13 are closed to control the temperature. In this way, the heat energy provided by catalytic combustion maintains the combustion bed 12 at a higher temperature without the need for continuous external energy supply.

[0030] When the temperature of the desorbed gas exceeds 125°C, the heat exchange air inlet valve 17 is opened to allow part of the gas after adsorption and purification to flow through the heat exchanger to reduce the temperature of the desorbed gas and keep it at about 120±5°C. A nitrogen pipeline II and a water spray pipeline III are provided in the device, and each activated carbon adsorption box is provided with a high temperature alarm system. When the temperature of the desorbed gas continues to rise and exceeds 130°C, the heat exchange air inlet valve 17 is adjusted to increase the air flow and the nitrogen air valve 2 is opened to cool the activated carbon box. If the temperature of the desorbed gas exceeds 135°C, the desorption fan 11 and the desorption circulation valve 10 are closed, the cooling and draining valve 14 is opened, the high temperature alarm system alarms, and the water spraying system is automatically opened to force the high temperature activated carbon box to cool down. When the desorption is completed, the air volume of the heat exchange air inlet valve 17 is increased to reduce the temperature of the desorbed gas to below 100°C; then the heat exchange air inlet valve 17 is closed, the cold air supplement valve 18 and the cooling and draining valve 14 are opened, and the desorption fan 11 and the desorption circulation valve 10 are closed to cool the activated carbon box. Since the desorption fan does not need to be used to induce air during the cooling process, its operation time can be reduced; and the low-temperature gas no longer passes through the catalytic combustion bed. Due to the effect of the insulation layer, the temperature in the combustion bed drops slowly, and the window can still maintain a high temperature during the next desorption cycle, which is beneficial to reduce power consumption. When the cooling is completed, the cold air valve 18, the cooling exhaust valve 14, the desorption inlet valve 7 and the desorption outlet valve 8 are closed, and the corresponding activated carbon adsorption box enters the adsorption state again.

[0031] The activated carbon adsorption box is provided with a glass window, and waterproof honeycomb activated carbon is used in the box.

[0032] The adsorption concentration high-temperature desorption catalytic combustion treatment device is equipped with a PLC control system. The induced draft fan, desorption fan, high-temperature alarm system, and infrared heating device of the catalytic combustion bed are all controlled by the PLC system; the air valves and water valves provided on the nitrogen pipeline, water spray pipeline, desorption air duct, adsorption air duct, cooling air duct, and heat exchange air duct are all controlled by the PLC system.

[0033] The above description is an explanation of the present invention and is not intended to limit the present invention. Other modified, combined and simplified technical solutions that do not deviate from the principles and spirit of the present invention are all included in the protection scope of the present invention.

Claims

1. A treatment process of a paint spraying organic waste gas adsorption concentration high temperature desorption catalytic combustion treatment device, characterized in that: The treatment device includes a filter, a plurality of parallel activated carbon adsorption boxes, an induced draft fan, a heat exchanger, a flame arrester filter, a desorption circulation valve, a desorption fan, a catalytic combustion bed, an exhaust pipe, an oxygen supply air valve, a cooling exhaust valve and a cold supply air valve; the characteristics are: The VOCs waste gas outlet is connected to the air inlet of the filter through a pipe I; the activated carbon adsorption box is provided with a VOCs adsorption inlet, an adsorption purification outlet, a desorption air supply inlet, and a desorption return air outlet; the filter air outlet is connected to the VOCs adsorption inlets of multiple parallel activated carbon adsorption boxes through an air duct; the adsorption purification outlet of the activated carbon adsorption box is connected to the induced draft fan through an air duct; air valves are provided on the air ducts; the adsorption purification outlet of the activated carbon adsorption box, the induced draft fan and the exhaust pipe are connected in sequence through air ducts; The air duct connecting the induced draft fan and the exhaust pipe is provided with a heat exchange branch pipe, which is connected to the air inlet of the heat exchanger and is provided with a heat exchange air inlet valve, and the air outlet of the heat exchanger is connected to the exhaust pipe through the air duct; the induced draft fan and the desorption main pipeline are provided with a cooling branch pipe, which is provided with a cold air supplement valve; the desorption return air outlet, the flame arrester filter, the desorption fan and the catalytic combustion bed of the activated carbon adsorption box are connected in sequence through the air duct, a desorption circulation valve is provided between the flame arrester filter and the desorption fan, an oxygen enrichment air duct is provided between the desorption circulation valve and the desorption fan, and an oxygen supplement air valve is provided; a cooling air duct is provided between the flame arrester filter and the exhaust pipe, and a cooling exhaust valve is provided; the catalytic combustion bed It is connected to the circulating air inlet of the heat exchanger through the circulating air duct, and the circulating air outlet of the heat exchanger is connected to the desorption main pipeline of the activated carbon adsorption box. A branch pipe is provided between the catalytic combustion bed and the exhaust pipe, and a combustion exhaust valve is provided. The activated carbon desorption main pipeline is connected to the activated carbon desorption air supply inlet through the branch pipes respectively; the catalytic combustion bed is provided with a far-infrared electric heating layer, a catalytic combustion layer, and a heat exchange layer; the desorption gas is maintained at 120±5℃ during the desorption process; the activated carbon adsorption box is equipped with a high temperature alarm system; the treatment device is provided with a nitrogen pipeline II and a water spray pipeline III, which are connected to each activated carbon adsorption box, and a corresponding air valve or water valve is provided on each connecting pipeline; The treatment process includes: 1) In the adsorption concentration process, the organic waste gas passes through a filter to remove dust and paint mist, and is adsorbed and purified by multiple parallel activated carbon adsorption boxes before being discharged from the exhaust pipe; 2) The treatment device adopts the "multi-absorption and one-desorption" process. An activated carbon adsorption box is always kept in the desorption state in the treatment device. When an activated carbon box is saturated with adsorption, its adsorption inlet valve and adsorption outlet valve are closed, and the cooling exhaust valve, cold air supply valve, and heat exchange inlet valve are ensured to be closed. At the beginning of desorption, the precious metal catalyst inside the catalytic combustion bed is preheated. When the bed reaches the predetermined temperature, the desorption fan and the desorption circulation valve, the desorption inlet valve, and the desorption outlet valve are turned on to switch it to the desorption regeneration state, and intermittent oxygen is supplemented to provide sufficient oxygen for combustion. When supplementing oxygen, the combustion exhaust valve is opened synchronously; 3) After desorption is completed, increase the air volume of the heat exchange inlet valve to reduce the desorption gas temperature to below 100°C, close the heat exchange inlet valve, open the cooling air valve and cooling exhaust valve, close the desorption fan and the desorption circulation valve, and use part of the purified exhaust gas to directly cool the activated carbon box; when cooling is completed, close the cooling air valve, cooling exhaust valve, desorption inlet valve and desorption outlet valve, open the adsorption inlet valve and adsorption outlet valve, and switch the activated carbon adsorption box to adsorption mode.

2. The treatment process of a paint spraying organic waste gas adsorption concentration high temperature desorption catalytic combustion treatment device according to claim 1 is characterized in that: The filter adopts a primary filter layer, a medium filter layer and an activated carbon sacrificial bed.

3. The treatment process of a paint spraying organic waste gas adsorption concentration high temperature desorption catalytic combustion treatment device according to claim 1 is characterized in that: The activated carbon adsorption box uses waterproof honeycomb activated carbon.

4. The treatment process of a paint spraying organic waste gas adsorption concentration high temperature desorption catalytic combustion treatment device according to claim 3 is characterized by: The activated carbon adsorption box is provided with a glass window.

5. The treatment process of a paint spraying organic waste gas adsorption concentration high temperature desorption catalytic combustion treatment device according to claim 1 is characterized in that: The outer wall of the catalytic combustion bed is provided with a high temperature resistant rock wool insulation layer.

6. The treatment process of a paint spraying organic waste gas adsorption concentration high temperature desorption catalytic combustion treatment device according to claim 1 is characterized in that: Equipped with a PLC control system, the induced draft fan, desorption fan, high temperature alarm system, and infrared heating device of the catalytic combustion bed are all controlled by the PLC system.

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