The application of wet cleaner technology in the ceramic industry in the management of flue gas and dust

2016-06-12 17:18:15

1 Preface
Building ceramics industry is a high pollution, high energy consumption of the industry. At present, a total of more than 2000 building ceramics production lines, production nearly reached 10 billion m2. The existing building ceramics industry flue gas discharge is much and scattered, no organization emissions serious, difficult to control, the industry not only to face the fierce competition, but also face the task of energy saving and emission reduction.
"Ceramic industrial pollutants emission standards" GB25464-2010 atmospheric pollutant emission standard 8.6%O2 of dust, SO2 and NOx emission requirements very strict, China Building sanitary ceramics enterprises to meet the enterprise does not exceed 2%. Due to the prevailing environmental protection technology is also difficult to support this standard, in 2014 building ceramics industry standards for the discharge of atmospheric pollutants (2014 modified single) will adjust the benchmark oxygen 18% temporarily relaxing the emission standards, but this is only a transitional standards, 2016 will introduced the new emission standards, and when the new environmental protection technology can support more stringent emission standards, new standards will more strictly. Therefore, in order to deal with the future of more stringent environmental standards, to explore and develop the application of ultra low emission control equipment for building ceramics industry is particularly urgent.
2 the status and control technology of flue gas dust in the building ceramics industry
2.1 current emission status and control technology
Building ceramic industrial flue gas from the furnace (generally using water gas as fuel) and the hot blast stove before the spray drying tower (generally using coal water slurry as fuel). The current building ceramics industry flue gas treatment technology is backward, outdated equipment, some rural areas are even not any environmental governance, directly to the flue gas generated in the process of ceramic production emissions into the atmosphere, the gas contains large amounts of dust and heavy metal etc., cause huge environmental pollution. Affected by the process, the dust concentration in the flue gas emitted by the spray drying tower was higher, and the initial dust emission concentration was 2200 to 5600mg/Nm3, as shown in table 1~ Table 2.
2.2 current problems in the treatment of flue gas dust and heavy metal
Building ceramics industry environmental protection technology level is backward, environmental protection equipment is old, the management efficiency is low, mainly in the following aspects:
(1) most of the ceramic kiln system has been equipped with wet desulfurization equipment, but not equipped with dust removal equipment, resulting in excessive dust concentration in the wet FGD export;
(2) wet desulfurization chimney flue gas at the outlet of the spray, droplet, especially desulfurization product (e.g., sodium sulfate content too much, resulting in the formation of blue or yellow plume.
(3) heavy metals in flue gas, such as lead (Pb), cadmium (Cd), nickel (Ni), as well as fluoride, chloride and other no removal facilities, did not get effective removal.
3 building ceramics industry flue dust ultra low emission equipment - wet cleaner
3.1 ultra low emission control targets
In order to avoid multiple environmental governance reform, leading the new ceramic industry, energy saving oriented and wet dust removal device can meet the ultra low emission control target, and compares it with the ceramic industry in 2010 and 2014 modified single emission standard of air pollutants, such as table 3 shows.
From table 3 it can be seen, ultra low emission target benchmark oxygen 18%, if converted into 8.6% oxygen benchmark, corresponding to the dust emission value was 20.7mg/Nm3, the emissions targets emission standards than ceramic industry GB25464-2010 but also strict. Therefore, ultra low emission targets can meet the ceramic industry's most stringent emission standards.
3.2 wet cleaner equipment introduction
From table 3 it can be seen, ultra low emission target benchmark oxygen 18%, if converted into 8.6% oxygen benchmark, corresponding to the dust emission value was 20.7mg/Nm3, the emissions targets emission standards than ceramic industry GB25464-2010 but also strict. Therefore, ultra low emission targets can meet the ceramic industry's most stringent emission standards.
3.2 wet cleaner equipment introduction
3.2.1 working principle
Wet cleaner is the use of strong electric field, a gas solid and liquid particles and gas separation purification system. In its electrode system, the high voltage direct current is connected with a strong electric field, which makes the surrounding gas ionization, producing a large number of electrons and positive ions. When the dust containing flue gas and water into the field, dust and fine droplets in the role of the electron and ion, fast charging and under the action of electric field force rapid trend and electrodes of opposite polarity, finally release charge and adsorption to the electrode. Due to the wet desulfurization process of water mist, dust coagulation and humidification, dust and mist in the electric field of charged, is collected together, mist on the collecting electrode formation water film, water film plate clean. Spray cleaning spray device with a certain pressure of water mist is sprayed to the surface of the electrode, accelerating containing dust drop along the surface of the positive electrode and the negative electrode down into the dust hopper, eventually discharged into a sedimentation tank, and the purified gas through a port is discharged into the atmosphere.
The basic process of wet cleaner is divided into three main stages:
(1) into the dust particles and water mist particle removal device in charge;
(2) movement and deposition of charged dust particles and droplets;
(3) spray cleaning device to clean the surface of the electrode to accelerate the dust off (that is, cleaning). Wet cleaner working principle as shown in figure 1.
Wet dust removal device working principle and traditional electric precipitator similar, rely on is static electricity, the difference is working in a "wet" a "dry".
3.2.2 wet cleaner structure
Wet dust removal device by import head, air distribution device, a bottom beam, an ash bucket, anode, cathode system, a shell, a export head, spray cleaning system, high voltage power supply devices, gray water processing system, electric control system etc.. Wet cleaner structure as shown in figure 2.
3.2.3 wet cleaner process
Dry dust removal device arranged in the front end of the wet flue gas desulfurization, wet dust removal device processing is the wet flue gas desulfurization arranged in the tail of dust removal and desulfurization system is flue gas treatment to the last door keepers. Wet cleaner process as shown in figure 3.
3.2.4 wet cleaner advantages
(1) high dust removal efficiency
Use water spray cleaning the electrode surface dust, no secondary dust, significantly reduced the export concentration of dust emissions, ensure precipitator outlet dust emission concentration is less than or equal to 5mg / Nm3, reached the national dust "near zero emissions" standard. In the furnace and spray drying tower, the rear end of the bag filter, can not basically solve the problem of excessive dust emissions.
(2) the reform of the workload is small
Only in the discharge of the chimney of the construction of the transformation of the construction, the entire production process system does not need to do any changes.
(3) PM2.5 fine dust and aerosol removal efficiency is high
Through the collection of wet dust removal device can be collected following flue gas wet desulfurization process in PM2.5 fine dust and aerosol, removal rate of > 90%, improve the transparency of flue gas emissions, meet the requirements of higher national air quality control.
(4) to solve the environmental problems of gypsum rain, smoke fog caused by wet desulfurization
Desulfurization tower of SO3 and water mist removal rate is very low, SO3 in aerosol form with mist and smoke discharge, resulting in downstream of the chimney, wind direction, often appear the phenomenon of "acid rain" and "gypsum rain", or is the long tail of smoke "blue smoke" phenomenon. To solve the above problems effectively through the wet cleaner, the removal rate of SO3 is 80%, the removal rate of water mist > > 60%.
(5) the removal efficiency of heavy metals in flue gas is high.
Through the wet dust removal device of the network, can collect follow-up flue gas wet desulfurization of lead (PB), cadmium (CD), nickel (Ni), fluoride (f), chloride and heavy metals, the removal rate of more than 60%.
(6) to completely solve the problem of the removal of viscous materials in flue gas
Kiln flue gas moisture content is too large, if uses the cloth sack dust remover, although the use of pure PTFE corrosion resistant filter, but sticky dust will stick to the bag surface, resulting in the paste bag phenomenon lead dust is not working, and wet decontamination is not the existence of the problem, viscous material to enter wet desulphurization absorption tower desulfurization and dedust, again into the wet dust removal device in the final and complete removal.
(7) the cleaner low running resistance
New wet dust removal device can own resistance with the original set of flue gas resistance, transformation don't need change the front end of each draft fan. And the furnace, such as the use of bag filter, the system will increase the running resistance of about 1800Pa, or even higher, eventually led to the dust collector can not operate normally.
4 Conclusion
Wet dust removal device can fundamentally solve the ceramic production line of dust emissions, can collect ultrafine dust, can collaborate to dispose of PM2.5, gypsum rain, heavy metals and other pollutants, to achieve the purpose of deep purification of flue gas, is the current ceramic production line flue gas treatment of the most advanced and reliable technology.