Rotating wheel catalytic combustion process for waste gas treatment of automobile repair baking finish house

Abstract

The invention discloses a rotating wheel catalytic combustion process for automobile repair baking finish house waste gas treatment, which comprises the following steps: pre-filtering waste gas, feeding the pre-filtered waste gas into an adsorption area of a concentration rotating wheel, performing normal-temperature adsorption, and discharging after reaching the standard; the rotating wheel rotates to a desorption area, adsorbed VOCs are desorbed and concentrated through gas at the temperature of 200 DEG C + / -20 DEG C, high-concentration organic waste gas enters a heat exchanger to be preheated after being desorbed, then enters a catalytic furnace and is heated to 350 DEG C (+ / -50) through a heater to be subjected to catalytic combustion, generated carbon dioxide and water vapor enter the heat exchanger to be subjected to heat exchange, and part of gas is conveyed to the desorption area to be continuously used for desorption of the rotating wheel; and the residual gas is circulated in the system and discharged through a chimney. The process can adopt two operation modes of'adsorption while desorption 'and'adsorption before desorption', the former operation mode is that the rotating wheel enters the desorption area for desorption after being adsorbed in the adsorption area, and then enters the catalytic combustion system for treatment, and the latter operation mode is that the desorption and catalytic combustion system is started for treatment after the rotating wheel rotates for adsorption saturation; by means of the process, the removal efficiency of the VOCs gas can reach 97% or above.

Description

Technical Field

[0001] The invention relates to the technical field of waste gas treatment in auto repair paint booths, and in particular to a rotary catalytic combustion process for waste gas treatment in auto repair paint booths. Background Art

[0002] The exhaust gas from auto repair paint booths contains paint mist particles and organic waste gas. The main components of organic waste gas are benzene, toluene, xylene and non-methane total hydrocarbons. With the vigorous development of my country's automobile industry, the paint exhaust gas generated by the auto repair industry is one of the causes of air pollution. Among them, the control of VOCs in paint exhaust gas has become an important part of air pollution control. Therefore, it is of great significance to strengthen the comprehensive control of VOCs in the auto repair industry.

[0003] At present, activated carbon is a commonly used VOCs adsorbent, but it has many problems such as difficulty in regeneration, poor moisture resistance, and flammability. The main solution for exhaust gas treatment in the auto repair industry is single activated carbon adsorption and regular carbon replacement. This mode is difficult to supervise environmental protection during operation, and requires regular carbon replacement to produce a large amount of hazardous waste, which greatly increases the operating costs of the enterprise. At the same time, there is a fire risk during the use and replacement of activated carbon, which poses a great safety hazard to auto repair companies. Therefore, we proposed a rotary catalytic combustion process for exhaust gas treatment in auto repair paint rooms to solve the above-mentioned problems. Summary of the invention

[0004] The purpose of the present invention is to provide a rotary catalytic combustion process for the treatment of exhaust gas in auto repair paint rooms, so as to solve the problem proposed in the above background technology that the main solution for exhaust gas treatment in the auto repair industry is currently a single activated carbon adsorption and regular carbon replacement mode. During the operation of this mode, environmental protection supervision is difficult, and regular carbon replacement is required to generate a large amount of hazardous waste, which greatly increases the operating costs of the enterprise. At the same time, there is a fire risk during the use and replacement of activated carbon, which poses a great safety hazard to auto repair companies.

[0005] To achieve the above object, the present invention provides the following technical solution: a rotary catalytic combustion process for treating exhaust gas in a paint room for auto repair, comprising the following process principles:

[0006] 1. Process

[0007] (1) Pretreatment system

[0008] Generally configured as G4, F7, F9 three-stage primary and secondary high efficiency exhaust gas filters or DPA, washable ceramic metal filters;

[0009] (2) Zeolite wheel adsorption system

[0010] After being filtered by the pretreatment system, the exhaust gas enters the adsorption zone of the concentration rotor for room temperature adsorption. After the VOCs gas passing through the rotor is adsorbed and purified by the adsorbent, it is discharged from the other side of the adsorption zone of the concentration rotor to the chimney;

[0011] (3) Zeolite wheel desorption and concentration system

[0012] The rotor moves to the desorption zone, where the VOCs adsorbed by the rotor are desorbed and concentrated by the gas at 200℃±20, and the concentrated gas enters the catalytic combustion system for treatment;

[0013] (4) Catalytic combustion (CO) system

[0014] After desorption, high-concentration organic waste gas enters the heat exchanger for preheating and then enters the catalytic furnace. It is heated to 350℃ (±50) by the heater for catalytic combustion. The generated carbon dioxide and water vapor enter the heat exchanger for heat exchange. Part of the gas is sent to the desorption area to continue to be used for desorption by the wheel and circulate in the system. The remaining gas is discharged through the chimney.

[0015] 2. Operating conditions

[0016] (1) The oil mist, acid (including organic acid), alkali (including organic alkali), resin, dust, polymeric substances, etc. contained in the exhaust gas must be removed through the pre-filtration system;

[0017] ①Oil mist<0.1mg / Nm3

[0018] ②Dust<1mg / Nm3

[0019] ③Acid>pH5

[0020] ④Alkali<pH7

[0021] ⑤Relative humidity <80%RH

[0022] (2) The equipment has 20000Nm 3 / h air volume and 40000Nm 3 / h air volume, two models, management is carried out according to this air volume. If the air volume is unbalanced, the purification efficiency will be reduced;

[0023] (3) The adsorption performance of the concentrator wheel is related to the composition of VOCs and the exhaust gas temperature. The exhaust gas temperature is 25°C. If the exhaust gas temperature exceeds 25°C, the adsorption performance will decrease; if it contains substances with low boiling points, the influence of the exhaust gas temperature will become more significant; if the exhaust gas temperature is below 0°C, frost will occur in the wheel, which will affect the adsorption performance;

[0024] (4) The inlet temperature of the regeneration zone is 180-220°C;

[0025] (5) Catalytic combustion technology can make organic waste gas burn flamelessly at a lower ignition temperature with the help of catalyst;

[0026] 3. High temperature regeneration

[0027] (1) Purpose

[0028] During the use of the zeolite wheel, if the VOCs gas contains high-boiling-point gases, the high-boiling-point substances cannot be desorbed at the normal desorption temperature (180-220°C) after the equipment has been running for a period of time, and gradually accumulate in the wheel, thus affecting the adsorption efficiency of the wheel. Therefore, the wheel needs to be regenerated at high temperature (300±5°C);

[0029] (2) High temperature regeneration process (see high temperature regeneration process diagram);

[0030] 4. Zeolite Rotor Adsorption Concentration System

[0031] The continuous process of "adsorption-desorption concentration-adsorption" is used to absorb, desorb and concentrate VOCs waste gas;

[0032] (1) The zeolite wheel is divided into an adsorption zone and a desorption zone. The two zones are separated by a sheet metal frame and sealed with heat-resistant and solvent-resistant sealing materials. The zeolite wheel operates continuously in each functional zone.

[0033] (2) After the waste gas passes through the pre-filtration system, it is sent to the adsorption area of ​​the zeolite wheel. In the adsorption area, VOCs in the organic waste gas are adsorbed and removed by the zeolite molecular sieve. After the organic waste gas is purified, it is discharged from the zeolite wheel treatment area;

[0034] (3) VOCs adsorbed in the zeolite wheel are desorbed and concentrated in the desorption zone by hot air treatment at about 200°C with a small air volume. The concentration multiple is generally 5 to 25 times.

[0035] (4) Each zeolite rotor system is equipped with a heat exchanger;

[0036] (5) Zeolite molecular sieves are used as VOCs adsorbents. The hydrophobicity of zeolite molecular sieves is adjustable. The hydrophilicity and hydrophobicity of the molecular sieves can be adjusted by adjusting the silicon-aluminum ratio of the molecular sieve framework. Zeolite molecular sieves with high silicon-aluminum ratios have excellent hydrophobic properties, which can effectively reduce the competitive adsorption of water on VOCs molecules under certain humidity conditions.

[0037] Preferably, the oil mist, acid (including organic acid), alkali (including organic alkali), resin, dust, and polymeric substances contained in the exhaust gas may cause the pores of the wheel to be blocked and the zeolite wheel adsorbent to deteriorate, and may also cause damage to the concentration wheel.

[0038] Preferably, the catalyst is a precious metal catalyst, the catalyst carrier is a honeycomb ceramic, and the amount of the catalyst is 0.03 m3 .

[0039] Preferably, factors affecting the life of the catalyst include:

[0040] Operating temperature T<600℃; air velocity greater than or equal to 10000h -1 ; Organic solvents containing Cl and N elements; Waste gas components and concentrations; O 2 concentration; product composition and concentration; catalyst strength and thermal shock resistance.

[0041] Compared with the prior art, the beneficial effects of the present invention are: the exhaust gas treatment of the auto repair paint room adopts the rotary catalytic combustion process;

[0042] 1. Zeolite molecular sieve is used as a VOCs adsorbent. The hydrophobicity of zeolite molecular sieve is adjustable. The hydrophilicity and hydrophobicity of the molecular sieve can be adjusted by adjusting the silicon-aluminum ratio of the molecular sieve framework. Zeolite molecular sieve with a high silicon-aluminum ratio has excellent hydrophobic properties, which can effectively reduce the competitive adsorption of water on VOCs molecules under certain humidity conditions;

[0043] 2. Uniform pore size distribution can effectively carry out molecular recognition, thereby greatly improving the selectivity and adsorption of VOCs by the adsorbent;

[0044] 3. Zeolite molecular sieves are generally composed of silicon and aluminum, which are non-flammable and have good hydrothermal stability. Therefore, they can be combined with other means such as microwave heating to reduce the energy consumption of adsorbent regeneration and improve operational safety;

[0045] 4. Zeolite molecular sieve has a large specific surface area and high adsorption capacity. It is an ideal material for adsorbents in honeycomb rotor adsorption technology. Zeolite molecular sieve is a simpler, more efficient and more selective VOCs adsorbent.

[0046] 5. Two operation modes are adopted: "absorption and desorption at the same time" and "absorption first and then desorption". The former is that the wheel enters the desorption zone for desorption after adsorption in the adsorption zone, and then enters the catalytic combustion system for treatment. The latter is to let the wheel rotate until the adsorption is saturated, and then start the desorption and catalytic combustion system for treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 This is a layout diagram of the purification equipment of the present invention;

[0048] Figure 2 This is the upper layout diagram of the purification equipment of the present invention;

[0049] Figure 3 This is the lower layout diagram of the purification equipment of the present invention;

[0050] Figure 4 It is a process flow chart of the present invention;

[0051] Figure 5 This is a high temperature regeneration flow chart of the present invention. DETAILED DESCRIPTION

[0052] The technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0053] See also Figure 1-Figure 5 The present invention provides the following technical solution: a rotary catalytic combustion process for treating exhaust gas from a paint room in an automobile repair shop, including the following process principles:

[0054] 1. Process

[0055] (1) Pretreatment system

[0056] Generally configured as G4, F7, F9 three-stage primary and secondary high efficiency exhaust gas filters or DPA, washable ceramic metal filters;

[0057] (2) Zeolite wheel adsorption system

[0058] After being filtered by the pretreatment system, the exhaust gas enters the adsorption zone of the concentration rotor for room temperature adsorption. After the VOCs gas passing through the rotor is adsorbed and purified by the adsorbent, it is discharged from the other side of the adsorption zone of the concentration rotor to the chimney;

[0059] (3) Zeolite wheel desorption and concentration system

[0060] The rotor moves to the desorption zone, where the VOCs adsorbed by the rotor are desorbed and concentrated by the gas at 200℃±20, and the concentrated gas enters the catalytic combustion system for treatment;

[0061] (4) Catalytic combustion (CO) system

[0062] After desorption, high-concentration organic waste gas enters the heat exchanger for preheating and then enters the catalytic furnace. It is heated to 350℃ (±50) by the heater for catalytic combustion. The generated carbon dioxide and water vapor enter the heat exchanger for heat exchange. A part of the gas is sent to the desorption area to continue to be used for desorption by the rotor and circulate in the system. The remaining gas is discharged through the chimney, which can achieve a removal efficiency of more than 97% for VOCs gas.

[0063] 2. Operating conditions

[0064] (1) The oil mist, acid (including organic acid), alkali (including organic alkali), resin, dust, polymeric substances, etc. contained in the exhaust gas must be removed through the pre-filtration system;

[0065] ①Oil mist<0.1mg / Nm3

[0066] ②Dust<1mg / Nm3

[0067] ③Acid>pH5

[0068] ④Alkali<pH7

[0069] ⑤Relative humidity <80%RH

[0070] (2) The equipment has 20000Nm 3 / h air volume and 40000Nm 3 / h air volume, two models, management is carried out according to this air volume. If the air volume is unbalanced, the purification efficiency will be reduced;

[0071] (3) The adsorption performance of the concentrator wheel is related to the composition of VOCs and the exhaust gas temperature. The exhaust gas temperature is 25°C. If the exhaust gas temperature exceeds 25°C, the adsorption performance will decrease; if it contains substances with low boiling points, the influence of the exhaust gas temperature will become more significant; if the exhaust gas temperature is below 0°C, frost will occur in the wheel, which will affect the adsorption performance;

[0072] (4) The inlet temperature of the regeneration zone is 180-220°C;

[0073] (5) Catalytic combustion technology can make organic waste gas burn flamelessly at a lower ignition temperature with the help of catalyst;

[0074] 3. High temperature regeneration

[0075] (1) Purpose

[0076] During the use of the zeolite wheel, if the VOCs gas contains high-boiling-point gases, the high-boiling-point substances cannot be desorbed at the normal desorption temperature (180-220°C) after the equipment has been running for a period of time, and gradually accumulate in the wheel, thus affecting the adsorption efficiency of the wheel. Therefore, the wheel needs to be regenerated at high temperature (300±5°C);

[0077] (2) High temperature regeneration process (see high temperature regeneration process diagram);

[0078] 4. Zeolite Rotor Adsorption Concentration System

[0079] The continuous process of "adsorption-desorption concentration-adsorption" is used to absorb, desorb and concentrate VOCs waste gas;

[0080] (1) The zeolite wheel is divided into an adsorption zone and a desorption zone. The two zones are separated by a sheet metal frame and sealed with heat-resistant and solvent-resistant sealing materials. The zeolite wheel operates continuously in each functional zone.

[0081] (2) After the waste gas passes through the pre-filtration system, it is sent to the adsorption area of ​​the zeolite wheel. In the adsorption area, VOCs in the organic waste gas are adsorbed and removed by the zeolite molecular sieve. After the organic waste gas is purified, it is discharged from the zeolite wheel treatment area;

[0082] (3) VOCs adsorbed in the zeolite wheel are desorbed and concentrated in the desorption zone by hot air treatment at about 200°C with a small air volume. The concentration multiple is generally 5 to 25 times.

[0083] (4) Each zeolite rotor system is equipped with a heat exchanger;

[0084] (5) Zeolite molecular sieves are used as VOCs adsorbents. The hydrophobicity of zeolite molecular sieves is adjustable. The hydrophilicity and hydrophobicity of the molecular sieve can be adjusted by regulating the silicon-aluminum ratio of the molecular sieve framework. Zeolite molecular sieves with high silicon-aluminum ratios have excellent hydrophobic properties, which can effectively reduce the competitive adsorption of water on VOCs molecules under certain humidity conditions.

[0085] The oil mist, acid (including organic acid), alkali (including organic alkali), resin, dust and polymeric substances contained in the exhaust gas will cause the impeller to become blocked and the zeolite impeller adsorbent to deteriorate, and may also cause damage to the concentrating impeller.

[0086] The catalyst is a precious metal catalyst, the catalyst carrier is a honeycomb ceramic, and the amount of the catalyst is 0.03m 3 .

[0087] The factors affecting the life of the catalyst include: operating temperature T < 600 ° C; space velocity greater than or equal to 10000h -1 ; Organic solvents containing Cl and N elements; Waste gas components and concentrations; O 2 concentration; product composition and concentration; catalyst strength and thermal shock resistance.

[0088] The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

[0089] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A rotary catalytic combustion process for treating exhaust gas from a paint shop in an automobile repair shop, characterized in that: The process principles include:

1. Process (1) Pretreatment system Generally configured as G4, F7, F9 three-stage primary and secondary high efficiency exhaust gas filters or DPA, washable ceramic metal filters; (2) Zeolite wheel adsorption system After being filtered by the pretreatment system, the exhaust gas enters the adsorption zone of the concentration rotor for room temperature adsorption. After the VOCs gas passing through the rotor is adsorbed and purified by the adsorbent, it is discharged from the other side of the adsorption zone of the concentration rotor to the chimney; (3) Zeolite wheel desorption and concentration system The rotor moves to the desorption zone, where the VOCs adsorbed by the rotor are desorbed and concentrated by the gas at 200℃±20, and the concentrated gas enters the catalytic combustion system for treatment; (4) Catalytic combustion (CO) system After desorption, high-concentration organic waste gas enters the heat exchanger for preheating and then enters the catalytic furnace. It is heated to 350℃ (±50) by the heater for catalytic combustion. The generated carbon dioxide and water vapor enter the heat exchanger for heat exchange. Part of the gas is sent to the desorption area to continue to be used for desorption by the wheel and circulate in the system. The remaining gas is discharged through the chimney.

2. Operating conditions (1) The oil mist, acid (including organic acid), alkali (including organic alkali), resin, dust, polymeric substances, etc. contained in the exhaust gas must be removed through the pre-filtration system; ①Oil mist<0.1mg / Nm3 ②Dust<1mg / Nm3 ③Acid>pH5 ④Alkali<pH7 ⑤Relative humidity <80%RH (2) The equipment has 20000Nm 3 / h air volume and 40000Nm 3 / h air volume, two models, management is carried out according to this air volume. If the air volume is unbalanced, the purification efficiency will be reduced; (3) The adsorption performance of the concentrator wheel is related to the composition of VOCs and the exhaust gas temperature. The exhaust gas temperature is 25°C. If the exhaust gas temperature exceeds 25°C, the adsorption performance will decrease; if it contains substances with low boiling points, the influence of the exhaust gas temperature will become more significant; if the exhaust gas temperature is below 0°C, frost will occur in the wheel, which will affect the adsorption performance; (4) The inlet temperature of the regeneration zone is 180-220°C; (5) Catalytic combustion technology can make organic waste gas burn flamelessly at a lower ignition temperature with the help of catalyst; 3. High temperature regeneration (1) Purpose During the use of the zeolite wheel, if the VOCs gas contains high-boiling-point gases, the high-boiling-point substances cannot be desorbed at the normal desorption temperature (180-220°C) after the equipment has been running for a period of time, and gradually accumulate in the wheel, thereby affecting the adsorption efficiency of the wheel. Therefore, the wheel needs to be regenerated at high temperature (300±5°C); (2) High temperature regeneration process (see high temperature regeneration process diagram); 4. Zeolite Rotor Adsorption Concentration System The continuous process of "adsorption-desorption concentration-adsorption" is used to absorb, desorb and concentrate VOCs waste gas; (1) The zeolite wheel is divided into an adsorption zone and a desorption zone. The two zones are separated by a sheet metal frame and sealed with heat-resistant and solvent-resistant sealing materials. The zeolite wheel operates continuously in each functional zone. (2) After the waste gas passes through the pre-filtration system, it is sent to the adsorption area of ​​the zeolite wheel. In the adsorption area, VOCs in the organic waste gas are adsorbed and removed by the zeolite molecular sieve. After the organic waste gas is purified, it is discharged from the zeolite wheel treatment area; (3) VOCs adsorbed in the zeolite wheel are desorbed and concentrated in the desorption zone by hot air treatment at about 200°C with a small air volume. The concentration multiple is generally 5 to 25 times. (4) Each zeolite rotor system is equipped with a heat exchanger; (5) Zeolite molecular sieves are used as VOCs adsorbents. The hydrophobicity of zeolite molecular sieves is adjustable. The hydrophilicity and hydrophobicity of the molecular sieve can be adjusted by regulating the silicon-aluminum ratio of the molecular sieve framework. Zeolite molecular sieves with high silicon-aluminum ratios have excellent hydrophobic properties, which can effectively reduce the competitive adsorption of water on VOCs molecules under certain humidity conditions.

2. The rotary catalytic combustion process for treating exhaust gas from a paint booth in an automobile repair shop according to claim 1 is characterized in that: The oil mist, acid (including organic acid), alkali (including organic alkali), resin, dust and polymeric substances contained in the exhaust gas may cause the impeller to be blocked and the zeolite impeller adsorbent to be degraded, and may also cause damage to the concentration impeller.

3. The rotary catalytic combustion process for treating exhaust gas from a paint booth in an automobile repair shop according to claim 1 is characterized in that: The catalyst is a precious metal catalyst, the catalyst carrier is a honeycomb ceramic, and the amount of the catalyst is 0.03 m 3 .

4. The rotary catalytic combustion process for treating exhaust gas from a paint booth in an automobile repair shop according to claim 1 is characterized in that: The factors affecting the life of the catalyst include: Operating temperature T<600℃; air velocity greater than or equal to 10000h -1 ; Organic solvents containing Cl and N elements; Waste gas composition and concentration; O2 concentration; Product composition and concentration; Catalyst strength and thermal shock resistance.

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