Background
The dyed and rinsed textile contains water, oil, solvent, paraffin and the like, and is heated, volatilized and cooled in the heat setting process, and the formed waste gas of the setting machine contains particulate matters, oil smoke and VOCs. Generally speaking, the exhaust gas flow of a single setting machine is 8000-10000m3The discharge temperature is 140 ℃ and 170 ℃, and the concentration of the particles is 150 ℃ and 250mg/m3The oil smoke concentration is 40-80mg/m3The concentration of VOCs is 20-50mg/m3. The above components can form dust haze and cause near-surface ozone pollution when being discharged into the atmosphere, and serious shadow is generatedAnd the air quality of the surrounding air of the area is affected.
The emission limit values are provided for particulate matters, dyeing and finishing oil smoke, VOCs, odor concentration, formaldehyde, benzene and benzene series emission in the national level-first local standard 'textile dyeing and finishing industry atmospheric pollutant emission standard' (DB 33/962-2015) in Zhejiang province of 3 months in 2015. At present, most of the waste gas treatment technologies adopted by printing and dyeing enterprises are water spraying and high-voltage static, and in addition, the technologies comprise water-gas heat exchange, dry static, gas-gas heat recovery, circulating spraying and washing, wet static, cooling high-voltage static and the like. Although the treatment route can effectively remove particulate matters and oil smoke (more than 80 percent), the treatment route also has the following defects: (1) because the waste gas contains combustible substances such as textile fibers, oil smoke and the like, the accumulation in the pollutant control device is easy to cause fire hazard and needs to be cleaned regularly; (2) no special VOCs processing unit is arranged; (3) when the purified exhaust gas is discharged, white smoke is generated due to condensation of water vapor.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide a system and a method for comprehensively treating waste gas of a setting machine.
The system for comprehensively treating the waste gas of the setting machine comprises a filter, a two-stage gas-gas heat exchanger, a spraying scrubber, a demister, a wet electrostatic dust collector, a photocatalytic reactor, an induced draft fan, a chimney, an oil-water separator and a water cooling tower; the waste gas of the setting machine is connected with a filter inlet, a filter outlet is connected with a shell pass inlet of a first-stage gas-gas heat exchanger, a shell pass outlet of the first-stage gas-gas heat exchanger is connected with a shell pass inlet of a second-stage gas-gas heat exchanger, a shell pass outlet of the second-stage gas-gas heat exchanger is connected with an inlet of a spray scrubber, an outlet of the spray scrubber is connected with an inlet of a demister, an outlet of the demister is connected with an inlet of a wet electrostatic dust collector, an outlet of the wet electrostatic dust collector is connected with a tube pass inlet of the second-stage gas-gas heat exchanger, a tube pass outlet of the second-stage gas-gas heat exchanger is connected with an inlet of a photocatalytic reactor, an outlet of the photocatalytic reactor is connected with a tube pass inlet of the first-stage; the oil-containing waste water discharge port of the two-stage gas-gas heat exchanger, the spray washer, the demister and the wet electrostatic precipitator is connected with the inlet of the oil-water separator, the waste water outlet of the oil-water separator is connected with the inlet of the water cooling tower, and the outlet of the water cooling tower is connected with the spray liquid storage tank of the spray washer.
Preferably, the method comprises the following steps: the filter adopts a dry filter, the mesh number of the filter screen of the dry filter is gradually increased along with the flowing direction of the waste gas, and the filter screen of the dry filter and the shell side of the two-stage gas-gas heat exchanger are both provided with online cleaning devices.
Preferably, the method comprises the following steps: the spraying washer is provided with an atomizing nozzle and is internally provided with a spray nozzle for two-stage spraying.
Preferably, the method comprises the following steps: the wet electrostatic dust collector adopts a vertical wet electrostatic dust collector or a horizontal wet electrostatic dust collector, the vertical wet electrostatic dust collector is preferably used for low oil smoke concentration purification, and the horizontal wet electrostatic dust collector is preferably used for high oil smoke concentration purification.
The treatment method of the system for comprehensively treating the waste gas of the setting machine comprises the following steps of:
1) the method comprises the following steps of preliminarily filtering the waste gas of the setting machine by using a filter, removing partial fiber dust and large particulate matters, and then reducing the temperature of the waste gas of the setting machine to be below 90 ℃ (for example, the temperature can be 90 ℃, 85 ℃, 80 ℃, 75 ℃ or 70 ℃ or a specific point value between the values) through the shell pass of a two-stage gas-gas heat exchanger, so that oil smoke particles are gradually condensed, and the subsequent facilities can conveniently remove the oil smoke particles;
2) the waste gas of the setting machine passing through the gas-gas heat exchanger is washed by a spray washer, the temperature of the waste gas of the setting machine is further reduced to be lower than 45 ℃ (for example, 45 ℃, 40 ℃, 35 ℃ or 30 ℃, or specific values between the values), most of particles and a small part of oil smoke are removed, and then the waste gas of the setting machine passes through a demister and enters a wet electrostatic dust collector (vertical or horizontal), so that most of particles and most of oil smoke are efficiently removed;
3) introducing oily wastewater generated by the waste gas of the setting machine after passing through a two-stage gas-gas heat exchanger, a spray scrubber, a demister and a wet electrostatic precipitator into an oil-water separator for oil-water separation, recovering the waste oil, discharging a small part of the wastewater to a wastewater treatment system, and cooling most of the wastewater by a water cooling tower and returning the wastewater to the spray scrubber for recycling;
4) the waste gas of the setting machine which is removed with most of particulate matters and oil smoke enters a tube pass of a second-stage gas-gas heat exchanger, then is heated to 50-60 ℃, then enters a photocatalytic reactor to degrade Volatile Organic Compounds (VOCs), finally enters a tube pass of a first-stage gas-gas heat exchanger to be further heated to over 75 ℃ (for example, 75 ℃, 80 ℃, 85 ℃ or 90 ℃), and is discharged through a draught fan and a chimney.
Preferably, the method comprises the following steps: and (3) in the step 1), the temperature of the waste gas of the setting machine is reduced to below 85 ℃ after passing through the shell pass of the two-stage gas-gas heat exchanger.
Preferably, the method comprises the following steps: and (3) in the step 2), the temperature of the waste gas of the setting machine is reduced to below 40 ℃ after passing through a spray washer.
Preferably, the method comprises the following steps: and 4) heating the waste gas of the setting machine in the step 4) to above 80 ℃ through a two-stage gas-gas heat exchanger, and discharging the waste gas through a draught fan and a chimney.
Preferably, the method comprises the following steps: and 4) adopting an ultraviolet light source in the photocatalytic reactor, wherein the photocatalytic reactor comprises a photolysis section and a photocatalytic reaction section.
The invention has the beneficial effects that:
(1) the requirement of high-efficiency control of multiple pollutants is met. According to the characteristics of the waste gas of the setting machine, the filter, the two-stage gas-gas heat exchanger, the spray washer, the demister, the wet electrostatic dust collector, the photocatalytic reactor, the induced draft fan, the oil-water separator, the water cooling tower and the like are combined to remove particulate matters, oil smoke and Volatile Organic Compounds (VOCs) in the waste gas of the setting machine, the preorder device provides support for the follow-up device to efficiently remove pollutants, the pollutant removal efficiency of the integrated system is remarkably improved through system optimization, and the requirement for controlling multiple pollutants in the waste gas of the setting machine at the same time is met.
(2) The safety and the stability are improved. Because the waste gas of the setting machine contains combustible components such as fiber dust, oil smoke and the like, the invention adopts a wet purification technical route to avoid the ignition risk of a dry purification system, and meanwhile, an online cleaning device is added into a filter, a gas-gas heat exchanger and other key devices which are easy to accumulate attachments, so that the running stability of the system is improved.
(3) The waste heat of the waste gas is utilized to realize 'white elimination' and simultaneously improve the removal efficiency of VOCs. The invention is based on the idea of 'white elimination' of reducing the moisture content of the waste gas in advance and then improving the emission temperature of the waste gas, reasonably sets the operation parameters of the system, realizes 'white elimination' without introducing an additional heat source, and arranges the photocatalytic reactor in a proper reaction temperature range according to the photocatalytic reaction principle and the characteristics of the photocatalytic reactor, thereby effectively improving the efficiency of removing VOCs by photocatalysis.
Detailed Description
The present invention will be further described with reference to the following examples. The following examples are set forth merely to aid in the understanding of the invention. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.
As shown in fig. 1, the system for comprehensively treating the waste gas of the setting machine comprises a filter 2, a two-stage gas-gas heat exchanger, a spray scrubber 5, a demister 6, a wet electrostatic precipitator 7, a photocatalytic reactor 8, an induced draft fan 9, a chimney 10, an oil-water separator 11 connected with the two-stage gas-gas heat exchanger, the spray scrubber 5, the demister 6 and the wet electrostatic precipitator 7, and a water cooling tower 12 connected with the oil-water separator 11.
Wherein, forming machine waste gas 1 is connected with 2 imports of filter, 2 exports of filter are connected with 3 shell side imports of first order gas heat exchanger, 3 shell side exports of first order gas heat exchanger are connected with 4 shell side imports of second grade gas heat exchanger, 4 shell side exports of second grade gas heat exchanger are connected with 5 imports of spraying scrubber, 5 exports of spraying scrubber are connected with 6 imports of defroster, 6 exports of defroster are connected with 7 imports of wet electrostatic precipitator, 7 exports of wet electrostatic precipitator are connected with 4 tube side imports of second grade gas heat exchanger, 4 tube side exports of second grade gas heat exchanger are connected with 8 imports of photocatalytic reactor, 8 exports of photocatalytic reactor are connected with 3 imports of first order gas heat exchanger, 3 exports of first order gas heat exchanger are connected with 9 imports of draught fan, 9 exports of draught fan are connected with the chimney.
In addition, the oil-containing waste water discharge port of the two-stage gas-gas heat exchanger, the spray washer 5, the demister 6 and the wet electrostatic precipitator 7 is connected with the inlet of the oil-water separator 11, the waste water outlet of the oil-water separator 11 is connected with the inlet of the water cooling tower 12, and the outlet of the water cooling tower 12 is connected with the spray liquid storage tank of the spray washer 5.
The filter 2 adopts dry filtration, which can filter out most of fiber dust and large particle substances and avoid the substances from depositing in the subsequent waste gas purification facility. The gas-gas heat exchanger cools the waste gas of the high-temperature setting machine to below 85 ℃, oil smoke particles in the waste gas are further agglomerated, the subsequent waste gas purification facility is convenient to collect, and the heat exchange amount is used for heating the low-temperature waste gas to eliminate white. The spray washer 5 adopts a high-pressure atomizing nozzle with the pressure of more than 4-5bar, is used for efficiently removing particles and a small part of oil smoke in the waste gas, the particle removal efficiency is more than 70 percent, the oil smoke removal efficiency is more than 20 percent, the load of the wet electrostatic dust collector is reduced, and simultaneously, the smoke is further cooled to be below 45 ℃, so that the white elimination effect is improved. The wet electrostatic precipitator 7 is in a vertical form and is provided with a high-frequency power supply, the high-frequency power supply is used for efficiently removing particles and oil smoke in the waste gas, the dust and oil smoke removing efficiency can reach more than 99%, and the waste gas is cooled to 40 ℃ again in the wet electrostatic precipitator 7. The low-temperature waste gas is heated to 50-60 ℃ after passing through the 4 tube passes of the second-stage gas-gas heat exchanger, then enters the photocatalytic reactor 8, the VOCs degradation efficiency is higher than 80%, harmful substances such as benzene, formaldehyde and the like can be effectively removed, then the temperature is heated to more than 80 ℃ again through the first-stage gas-gas heat exchanger 3, and the waste gas is discharged, and the discharged waste gas does not generate white smoke because the discharge temperature of the waste gas is far higher than the saturated vapor pressure of vapor in the waste gas, so that the 'white smoke elimination' is realized.
The waste water produced in the process enters an oil-water separator 11 to recover waste oil, enters a water cooling tower 12, is cooled by more than 5 ℃ and enters a spray tower to be sprayed circularly.
The applicant states that the present invention is illustrated by the above examples to show the detailed process equipment and process flow of the present invention, but the present invention is not limited to the above detailed process equipment and process flow, i.e. it does not mean that the present invention must rely on the above detailed process equipment and process flow to be implemented. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.