Waste gas treatment energy-saving control system suitable for two working conditions of paint spraying and curing of coating line

Abstract

The invention discloses a waste gas treatment energy-saving control system suitable for two working conditions of paint spraying and curing of a coating line, which comprises an adsorption fan, a desorption fan, a rotating wheel motor, an organic pollutant concentration detector, a temperature transmitter, a pressure transmitter, a differential pressure transmitter, a fuel flow meter, a desorption regulating valve and the like, the energy-saving control system for waste gas treatment is used for realizing effective energy conservation under two working conditions of paint spraying (large air volume and high concentration) and solidification (small air volume and low concentration) of a coating line under the condition of meeting up-to-standard emission, and the concentration of pollutants in gas from the coating line is monitored in real time through an organic pollutant concentration detector on a waste gas inlet header pipe; therefore, the real-time working condition of the coating line at the moment is judged. The method is suitable for energy-saving control of a shipyard painting line waste gas treatment system and can also be used for variable working condition energy-saving control of a rotating wheel and oxidation waste gas treatment system.

Description

Technical Field

[0001] The present invention relates to energy-saving control of an exhaust gas treatment system (rotor + catalytic oxidation equipment or rotor + regenerative heat oxidation furnace) of a shipyard painting line (including two working conditions of painting and curing), and can also be used for variable working condition energy-saving control of a rotor + oxidation exhaust gas treatment system. Background Art

[0002] The shipyard painting line is divided into two working conditions: painting and curing according to production requirements. The exhaust gas discharged during painting has the characteristics of large air volume and high concentration. After stopping painting, it enters the curing condition. The curing condition lasts for a long time, and the pollutant concentration gradually decreases, which has the characteristics of small air volume and low concentration. At present, the shipyard painting line usually adopts a rotor + catalytic oxidation equipment or a rotor + regenerative heat oxidation furnace exhaust gas treatment system to purify the exhaust gas. In order to meet the emission standards under the painting condition, the installed air volume and purification efficiency of the rotor and oxidation equipment are relatively high, resulting in the exhaust gas in the curing stage entering the same treatment system. Only the concentration multiple under the curing condition is changed, and the system energy consumption will be greatly increased. In order to solve the above problems, it is necessary to design an exhaust gas treatment energy-saving control system suitable for both painting and curing conditions of the painting line. Summary of the invention

[0003] The purpose of the present invention is to provide an energy-saving control system for waste gas treatment suitable for both painting and curing working conditions of a coating line.

[0004] The technical solution to achieve the purpose of the present invention is: an exhaust gas treatment energy-saving control system suitable for both painting and curing working conditions of a coating line. The exhaust gas treatment energy-saving control system includes an adsorption fan, a desorption fan, a rotary motor, an organic pollutant concentration detector, a temperature transmitter, a pressure transmitter, a differential pressure transmitter, a fuel flow meter and a desorption regulating valve. The exhaust gas treatment energy-saving control is completed according to the real-time working conditions of the coating line, as follows: 1) When the coating line is in the painting working condition, the adsorption fan is frequency-converted according to the set value of the pressure transmitter of the air intake manifold, and the pressure detection value reaches the set value by increasing or decreasing the frequency; the rotor motor operates according to the frequency setting value of the large air volume working condition; the desorption fan is frequency-converted according to the set value of the differential pressure transmitter of the rotor desorption zone, and the pressure difference detection value of the desorption zone reaches the set value by increasing or decreasing the frequency; 2) When the coating line enters the initial curing condition, the adsorption fan changes frequency according to the pressure transmitter setting value of the air intake manifold, and the pressure detection value reaches the set value by increasing or decreasing the frequency; the rotary motor operates according to the frequency setting value of the large air volume condition; the desorption fan changes frequency according to the temperature transmitter setting value of the air intake pipeline in front of the electric heater or the flow meter value of the fuel pipeline of the burner, and the actual temperature detection value of the air intake pipeline in front of the electric heater reaches the set value by decreasing the frequency, or the real-time detection value of the flow meter of the fuel pipeline is 0; 3) When the coating line enters the mid-curing condition, the adsorption fan frequency is reduced to the low-frequency operation setting value; the rotary motor operates according to the frequency setting value of the small air volume condition; the desorption fan frequency is changed according to the temperature transmitter setting value of the air intake pipe in front of the electric heater or the flow meter value of the fuel pipe of the burner, and the actual temperature detection value of the air intake pipe in front of the electric heater reaches the setting value by reducing the frequency, or the real-time detection value of the flow meter of the fuel pipe is 0, until it drops to the lowest frequency setting value, after which the desorption regulating valve starts to act, and the valve opening is adjusted according to the temperature transmitter setting value of the air intake pipe in front of the electric heater or the flow meter value of the fuel pipe of the burner, and the actual temperature detection value of the air intake pipe in front of the electric heater reaches the setting value by reducing the opening, or the real-time detection value of the flow meter of the fuel pipe is 0, until the minimum desorption air volume is reached; 4) When the coating line enters the final stage of curing, the exhaust gas treatment system enters the shutdown or standby program.

[0005] Furthermore, the adsorption fan, desorption fan and rotor motor are all frequency-controlled.

[0006] Furthermore, the operating frequency of the adsorption fan is controlled by the pressure transmitter of the gas main, or is operated at a fixed low-frequency setting value of 25 Hz, wherein the setting value of the pressure transmitter is a negative pressure, which is determined according to the pressure loss of the front-end collection network.

[0007] Furthermore, the operating frequency of the desorption fan is controlled by the differential pressure transmitter at both ends of the desorption zone of the rotor, or is changed according to the setting value of the temperature transmitter of the air intake pipeline before the electric heater or the flow meter count value of the fuel pipeline of the burner, but not lower than the minimum frequency setting value of 20Hz. The minimum desorption air volume is related to the rotor form and the area of ​​the rotor desorption zone.

[0008] Furthermore, the operating frequency of the rotor motor is a debugging set value, which is divided into a frequency setting value for a large air volume condition and a frequency setting value for a large air volume condition, and is determined according to specific air volume and concentration values.

[0009] Furthermore, the organic pollutant concentration detector is in the form of FID detection, which is used to determine the real-time working conditions of the coating line, including: When the pollutant concentration is higher than a certain value A, the value range of A is 800~1000mg / m, and the coating line is in the painting condition; When the pollutant concentration is lower than value A and higher than value B, the value range of B is 200~400mg / m3, and the coating line enters the initial curing condition; When the pollutant concentration is lower than the value B, the value range of B is 200~400mg / m3, and the coating line enters the mid-curing condition; When the pollutant concentration is lower than the value C, the value range of C is 30~50mg / m3. The value C is lower than the emission value required by the emission standard. At this time, the coating line enters the final curing condition.

[0010] Furthermore, the desorption regulating valve is an electric regulating valve equipped with a positioner to monitor and feedback the valve opening in real time.

[0011] Furthermore, organic pollutant concentration detectors, temperature transmitters, pressure transmitters, differential pressure transmitters, and fuel flow meters are all analog output instruments, and their accuracy level must not be higher than 0.5.

[0012] Compared with the prior art, the present invention has the following beneficial effects: 1) According to the organic pollutant concentration detection value on the exhaust gas intake main pipe, the curing condition is divided into three stages: initial curing, mid-curing and final curing. The operating states of the adsorption fan, desorption fan, rotor motor and desorption regulating valve are different in the three stages; 2) The minimum frequency setting value of the desorption fan under low concentration conditions is limited, which reduces the useless work of the fan motor and saves energy consumption; at the same time, a desorption regulating valve is designed to reduce the desorption air volume, increase the concentration of pollutants entering the oxidation system as much as possible, and reduce the heating energy consumption of the oxidation system; 3) Incorporate the temperature transmitter of the air intake pipe before the electric heater of the oxidation system or the flow meter of the fuel pipe of the burner into the control system to extend the self-heating operation time of the oxidation system. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a schematic diagram of an exhaust gas treatment energy-saving control system suitable for both painting and curing operations on a coating line. DETAILED DESCRIPTION

[0014] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0015] The present invention discloses an energy-saving control system for waste gas treatment applicable to both painting and curing working conditions of a coating line, including an adsorption fan, a desorption fan, a rotor motor, an organic pollutant concentration detector, a temperature transmitter, a pressure transmitter, a differential pressure transmitter, a fuel flow meter, and a desorption regulating valve, etc. The design and system are applicable to the energy-saving control of the waste gas treatment system (rotor + catalytic oxidation equipment or rotor + regenerative thermal oxidation furnace) of a shipyard coating line (including both painting and curing working conditions), and can also be used for the variable working condition energy-saving control of the rotor + oxidation waste gas treatment system.

[0016] Adsorption fan 1, desorption fan 2, rotary motor 3, organic pollutant concentration detector 4, temperature transmitter 5, pressure transmitter 6, differential pressure transmitter 7, fuel flow meter 8 and desorption regulating valve 9 constitute the main control points of the waste gas treatment energy-saving control system. It mainly solves the problem of the same waste gas treatment system meeting the emission standards and effectively saving energy under the two working conditions of painting line (large air volume and high concentration) and curing (small air volume and low concentration).

[0017] The exhaust gas treatment energy-saving control system monitors the concentration of pollutants in the exhaust gas from the coating line in real time through the organic pollutant concentration detector on the exhaust gas intake main pipe, thereby judging the real-time working condition of the coating line at this time; When the pollutant concentration is higher than a certain value A, usually the value range of A is (800~1000mg / m3), and the coating line is in the painting condition. At this time, the adsorption fan of the exhaust gas treatment system is frequency-converted according to the set value of the pressure transmitter of the air intake manifold. The set value of the pressure transmitter is usually negative pressure. The specific value is determined according to the pressure loss of the front-end collection network. The adsorption fan increases or decreases the frequency to make the actual pressure detection value reach the set value; the rotor motor runs according to the frequency setting value of the large air volume condition, and the desorption fan is frequency-converted according to the set value of the differential pressure transmitter of the rotor desorption zone. The desorption fan increases or decreases the frequency to make the actual pressure difference detection value of the desorption zone reach the set value; When the pollutant concentration is lower than value A and higher than value B, the value range of B is usually (200~400mg / m3), and the coating line enters the initial curing condition. At this time, the adsorption fan of the exhaust gas treatment system changes frequency according to the set value of the pressure transmitter of the air intake manifold. The set value of the pressure transmitter is usually negative pressure. The specific value is determined according to the pressure loss of the front-end collection network. The adsorption fan increases or decreases the frequency to make the actual pressure detection value reach the set value; the rotary motor runs according to the frequency setting value of the large air volume condition, and the desorption fan changes frequency according to the temperature transmitter setting value of the air intake pipeline in front of the electric heater (usually 280~300℃) or the flow meter value of the fuel pipeline of the burner. The desorption fan reduces the frequency to make the actual temperature detection value of the air intake pipeline in front of the electric heater reach the set value, or the real-time detection value of the flow meter of the fuel pipeline is 0; When the pollutant concentration is lower than the value B, usually the value range of B is (200~400mg / m3), the coating line enters the mid-curing condition. At this time, the adsorption fan of the exhaust gas treatment system is reduced to the low-frequency operation setting value (usually 25Hz), and the rotor motor operates according to the frequency setting value of the small air volume condition. The desorption fan is frequency-converted according to the temperature transmitter setting value of the air intake pipe before the electric heater or the flow meter value of the fuel pipe of the burner. The desorption fan reduces the frequency to make the actual temperature detection value of the air intake pipe before the electric heater reach the set value, or the flow meter of the fuel pipe reaches the set value. The real-time detection value is 0 until it drops to the minimum frequency setting value (usually 20Hz), after which the desorption regulating valve starts to act, and the valve opening is adjusted according to the setting value of the temperature transmitter of the air intake pipeline in front of the electric heater (usually 280~300℃) or the flow meter value of the fuel pipeline of the burner. The desorption regulating valve reduces the opening so that the actual temperature detection value of the air intake pipeline in front of the electric heater reaches the setting value, or the real-time detection value of the flow meter of the fuel pipeline is 0, until the minimum desorption air volume is reached, that is, the valve opening will no longer decrease when the differential pressure transmitter in the desorption zone reaches the minimum setting value; When the pollutant concentration is lower than the value C, usually the value range of C is (30~50mg / m3), the value C is lower than the emission value required by the emission standard. At this time, the coating line enters the final curing condition, and the exhaust gas treatment system enters the shutdown or standby program.

[0018] The adsorption fan 1, the desorption fan 2 and the rotor motor 3 are all frequency-converter controlled.

[0019] The operating frequency of the adsorption fan 1 is controlled by the pressure transmitter 6 on the air intake manifold, or is operated at a fixed low-frequency operating set value of 25 Hz.

[0020] The operating frequency of the desorption fan 2 is controlled by the differential pressure transmitter 7 at both ends of the rotor desorption zone, or is frequency-changed according to the set value of the temperature transmitter 5 of the air intake pipe before the electric heater of the oxidation system (usually 280~300℃) or the flow meter 8 value of the fuel pipe of the burner, but not less than the minimum frequency set value, usually 20Hz. The set value of the temperature transmitter of the air intake pipe before the electric heater in the catalytic oxidation system is usually 300℃.

[0021] The operating frequency of the rotary motor 3 is a debugging setting value, which is divided into a frequency setting value for a large air volume condition and a frequency setting value for a large air volume condition; the frequency setting value of the rotary motor needs to be determined according to the specific air volume and concentration value.

[0022] The desorption regulating valve 9 is an electric regulating valve with a matching positioner, which can monitor and feedback the valve opening in real time. The desorption regulating valve 9 only operates when the detection value of the organic pollutant concentration detector 4 is lower than the B value. The opening is adjusted according to the setting value of the temperature transmitter 5 of the air intake pipeline before the oxidation system electric heater or the flow meter 8 value of the fuel pipeline of the burner until the desorption zone differential pressure transmitter 7 reaches the minimum setting value. The minimum desorption zone pressure difference corresponds to the minimum desorption air volume. The minimum desorption air volume is related to the disc or cylinder type of the rotor and the area of ​​the rotor desorption zone.

[0023] The organic pollutant concentration detector 4 is in the form of FID detection, and its detection value determines the exhaust gas working condition as painting, initial curing, mid-curing and final curing stages, and serves as an input condition to control the operating status of the adsorption fan 1, desorption fan 2, rotary motor 3 and desorption regulating valve 9.

[0024] The organic pollutant concentration detector 4, temperature transmitter 5, pressure transmitter 6, differential pressure transmitter 7, and fuel flow meter 8 are all analog output instruments with an output of 4-20mA. The accuracy level must be no higher than level 0.5, and they are usually explosion-proof instruments with an explosion-proof level no lower than ExdIIBT4.

[0025] Finally, it should be noted that: although the present invention has been described in detail, ordinary technicians in this field should understand that they can still modify the aforementioned technical solutions, or make equivalent replacements for some or all of the technical features therein; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions implemented in the present invention.

Claims

1. An energy-saving control system for waste gas treatment applicable to both painting and curing working conditions of a coating line, the waste gas treatment energy-saving control system comprises an adsorption fan, a desorption fan, a rotary motor, an organic pollutant concentration detector, a temperature transmitter, a pressure transmitter, a differential pressure transmitter, a fuel flow meter and a desorption regulating valve, characterized in that: Complete the energy-saving control of exhaust gas treatment according to the real-time working conditions of the coating line, as follows: 1) When the coating line is in the painting working condition, the adsorption fan is frequency-converted according to the set value of the pressure transmitter of the air intake manifold, and the pressure detection value reaches the set value by increasing or decreasing the frequency; the rotor motor operates according to the frequency setting value of the large air volume working condition; the desorption fan is frequency-converted according to the set value of the differential pressure transmitter of the rotor desorption zone, and the pressure difference detection value of the desorption zone reaches the set value by increasing or decreasing the frequency; 2) When the coating line enters the initial curing condition, the adsorption fan changes frequency according to the pressure transmitter setting value of the air intake manifold, and the pressure detection value reaches the set value by increasing or decreasing the frequency; the rotary motor operates according to the frequency setting value of the large air volume condition; the desorption fan changes frequency according to the temperature transmitter setting value of the air intake pipeline in front of the electric heater or the flow meter value of the fuel pipeline of the burner, and the actual temperature detection value of the air intake pipeline in front of the electric heater reaches the set value by decreasing the frequency, or the real-time detection value of the flow meter of the fuel pipeline is 0; 3) When the coating line enters the mid-curing condition, the adsorption fan frequency is reduced to the low-frequency operation setting value; the rotary motor operates according to the frequency setting value of the small air volume condition; the desorption fan frequency is changed according to the temperature transmitter setting value of the air intake pipe in front of the electric heater or the flow meter value of the fuel pipe of the burner, and the actual temperature detection value of the air intake pipe in front of the electric heater reaches the setting value by reducing the frequency, or the real-time detection value of the flow meter of the fuel pipe is 0, until it drops to the lowest frequency setting value, after which the desorption regulating valve starts to act, and the valve opening is adjusted according to the temperature transmitter setting value of the air intake pipe in front of the electric heater or the flow meter value of the fuel pipe of the burner, and the actual temperature detection value of the air intake pipe in front of the electric heater reaches the setting value by reducing the opening, or the real-time detection value of the flow meter of the fuel pipe is 0, until the minimum desorption air volume is reached; 4) When the coating line enters the final stage of curing, the exhaust gas treatment system enters the shutdown or standby program.

2. The exhaust gas treatment energy-saving control system suitable for both painting and curing working conditions of a coating line according to claim 1 is characterized in that: The adsorption fan, desorption fan and rotor motor are all frequency-controlled.

3. The exhaust gas treatment energy-saving control system suitable for both painting and curing working conditions of a coating line according to claim 1 is characterized in that: The operating frequency of the adsorption fan is controlled by the pressure transmitter of the gas main, or it is operated at a fixed low-frequency setting value of 25Hz, where the setting value of the pressure transmitter is negative pressure, which is determined according to the pressure loss of the front-end collection pipe network.

4. The exhaust gas treatment energy-saving control system suitable for both painting and curing working conditions of a coating line according to claim 1 is characterized in that: The operating frequency of the desorption fan is controlled by the differential pressure transmitter at both ends of the desorption zone of the rotor, or is changed according to the setting value of the temperature transmitter of the air intake pipeline before the electric heater or the flow meter count value of the fuel pipeline of the burner, but not less than the minimum frequency setting value of 20Hz. The minimum desorption air volume is related to the rotor form and the area of ​​the rotor desorption zone.

5. The exhaust gas treatment energy-saving control system suitable for both painting and curing working conditions of a coating line according to claim 1 is characterized in that: The operating frequency of the rotor motor is the debugging setting value, which is divided into the frequency setting value for large air volume conditions and the frequency setting value for large air volume conditions, which is determined according to the specific air volume and concentration values.

6. The exhaust gas treatment energy-saving control system suitable for both painting and curing working conditions of a coating line according to claim 1 is characterized in that: The organic pollutant concentration detector is a FID detection form, which is used to determine the real-time working conditions of the coating line, including: When the pollutant concentration is higher than a certain value A, the value range of A is 800~1000mg / m, and the coating line is in the painting condition; When the pollutant concentration is lower than value A and higher than value B, the value range of B is 200~400mg / m3, and the coating line enters the initial curing condition; When the pollutant concentration is lower than the value B, the value range of B is 200~400mg / m3, and the coating line enters the mid-curing condition; When the pollutant concentration is lower than the value C, the value range of C is 30~50mg / m3. The value C is lower than the emission value required by the emission standard. At this time, the coating line enters the final curing condition.

7. The exhaust gas treatment energy-saving control system suitable for both painting and curing working conditions of a coating line according to claim 1 is characterized in that: The desorption regulating valve is an electric regulating valve equipped with a positioner to monitor and feedback the valve opening in real time.

8. The exhaust gas treatment energy-saving control system applicable to both painting and curing working conditions of a coating line according to claim 1 is characterized in that: Organic pollutant concentration detectors, temperature transmitters, pressure transmitters, differential pressure transmitters, and fuel flow meters are all analog output instruments, and their accuracy level must not be higher than 0.5.

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