Background technology
Pollutant has obtained lot of domestic and foreign environmental science and technology worker's approval in the lower temperature plasma technology degraded environment.Dielectric barrier discharge (Dielectric Barrier Discharge is called for short DBD) technology degraded VOC (Volatile Organic Compound is called for short VOC) has very high efficient.Some researchers utilize the DBD technology to carry out the research work of aspects such as the desulfurization of flue gas, resolving harmful gas and purifying automobile tail gas.China utility model patent ZL200520053401.X has announced a kind of dielectric barrier discharge plasma gas cleaning plant.Comprise cabinet, plasma generator, blower fan, on the cabinet, the bottom is respectively equipped with the gas outlet, air inlet, blower fan is arranged at cabinet bottom and corresponding with air inlet, plasma generator is positioned at the blower fan top, and be connected with the high-voltage pulse AC power, plasma generator comprises that plate electrode is right, framework, plate electrode is to being fixedly mounted in the framework, two right electrodes of plate electrode comprise insulating barrier respectively, conductor layer, insulating barrier and conductor layer are combined closely, and insulating barrier contacts with gas, insulating barrier comprises quartz, pottery, epoxy resin or ABS engineering plastics, its thickness is 0.5~3mm, plate electrode is 3~20mm to the spacing of two electrodes, the right area of plate electrode is 0.5~100mm2, and its quantity is 1~12 group.This device plasma is even, stable, energy consumption is low, the gas treatment amount is big, especially be fit to the processing of the organic exhaust gas of atm number low concentration, but because some accessory substance of plasma degradation process is optionally uncontrollable, can produce some harmful products (as ozone, carbon monoxide etc.), cause secondary pollution.Although degradation rate, increase CO that plasma combines with catalysis and can improve VOCs
2Selectivity, and further cut down the consumption of energy, but the secondary pollution that harmful substance ozone brings still exists.How effectively reducing the ozone secondary pollution problem that low temperature plasma air-treatment technology exists, is the key that concerns these technology survival and development.Develop a kind of ozone decomposition technique and device that matches with low temperature plasma air-treatment technology, have realistic meaning and higher market popularization value.
The utility model content
The purpose of this utility model is to reduce ozone concentration in the plasma air-treatment tail gas, and a kind of air cleaning of dielectric barrier discharge plasma efficiently exhaust gas processing device is provided.
Ozone is a kind of harmful gas with excitant special odor, and concentration is 0.3mg/m
3The time, eye nose larynx there is sensation; When concentration ozone surpassed 3~30mg/L, symptoms such as headache and respiratory apparatus local paralysis appearred.The permissible value of China's regulation ozone is decided to be 0.1ppm/8h.And in the low temperature plasma air cleaning tail gas ozone concentration up to several ppm.Ozone oxidation is very strong, and metal material and nonmetallic materials are all had strong corrosiveness.Be the allotrope of oxygen, the natural decomposition of gas ozone at room temperature needs a few hours, and content is the ozone below 1%, and half life of decomposition is about 16h in the air of normal temperature and pressure.Along with the rising of temperature, decomposition rate is accelerated, and when temperature surpassed 100 ℃, it was very fierce to decompose, and when arriving 270 ℃, can be converted into oxygen immediately.
In the air dielectric barrier discharge plasma process, when electron energy in the plasma field surpassed 8.4eV, oxygen decomposed generation ozone.The ionization energy of ozone molecule is 2eV, and energy is the accelerated decomposition that the electronics of 2~2.8eV helps ozone.
Gas after dielectric barrier discharge plasma is handled enters in the ozone treatment device, distance between ozone treatment device two-plate is 2-2.5 a times of dielectric barrier discharge reactor two-plate spacing, so electric-field intensity is about 0.4 to 0.5 times of electric-field intensity between dielectric barrier discharge reactor two-plate between ozone treatment device two-plate, electric field is not enough to cause gas discharge between ozone treatment device two-plate, but can make the charged particle that enters wherein produce acceleration, improve the charged particle energy, charged particle and ozone molecule collision promote the decomposition of ozone molecule, thereby reduce ozone concentration in the tail gas.Simultaneously, woven wire produces certain electric current in circuit behind the certain charged particle of absorption, and woven wire can keep higher temperature thus, and the woven wire pole plate helps increasing the contact area of handling gas and pole plate, and the absorption ozone molecule increases ozone and decomposes.
The purpose of this utility model is achieved through the following technical solutions:
A kind of dielectric barrier discharge plasma air-treatment ozone treatment device comprises the metallic sieve high-pressure stage and the woven wire low pressure utmost point; The metallic sieve high-pressure stage and the woven wire low pressure utmost point are disposed on the plasma reactor top successively; Distance between the metallic sieve high-pressure stage and the woven wire low pressure utmost point be the high-pressure side of plasma reactor and earth terminal tight attached insulating ceramics distance between plates 2-2.5 doubly, the high-pressure side parallel connection of metallic sieve high-pressure stage and plasma reactor, the earth terminal parallel connection of the woven wire low pressure utmost point and plasma reactor.
For further realizing the purpose of this utility model, described plasma reactor is a kind of dielectric barrier discharge plasma reactor.
Described dielectric barrier discharge plasma reactor is done dielectric barrier with the polylith insulated ceramic plates, and insulated ceramic plates is provided with metallic conductor, is respectively high-pressure side or earth terminal; The insulated ceramic plates that is provided with high-pressure side is provided with successively at interval with the insulated ceramic plates that is provided with earth terminal, and the insulated ceramic plates that is provided with high-pressure side is 2-5mm with the spacing that is provided with the insulated ceramic plates of earth terminal.
Described woven wire low pressure utmost point thickness is 3.5cm.
Described metallic sieve high pressure very has the platy structure of screen cloth, adopts the 80-120 eye mesh screen.
For prior art, the utlity model has following advantage:
1) electronics utilization ratio height.What have the degradation of contaminant ability in the plasma discharge process is high energy particle and active specy, Electron energy distribution is similar to Maxwell's distribution in the plasma discharge process, low energy electrons quantity is far more than the quantity of high energy electron, utilize the ozone in the low-energy relatively electron process plasma degradation process tail gas, improved the electronic efficiency in the plasma discharge process.
2) compact equipment.The utility model adopts and the similar bi-medium to block structure of medium barrier plasma reactor, only dual dielectric layer is used to guarantee that apart from increase ozone treatment device internal electric field intensity is 0.4 to 0.5 times of dielectric barrier discharge plasma reactor internal electric field intensity, institute takes up space little, and the volume of the part of the vent gas treatment in can effective less plasma air processor, make the device overall structure compacter.
The specific embodiment
For further understanding the utility model, below in conjunction with accompanying drawing the utility model is further described, need to prove that the specific embodiment is not construed as limiting the claimed scope of the utility model.
As shown in Figure 1, a kind of dielectric barrier discharge plasma air-treatment ozone treatment device comprises the metallic sieve high-pressure stage 1 and the woven wire low pressure utmost point 2; The metallic sieve high-pressure stage 1 and the woven wire low pressure utmost point 2 are disposed on plasma reactor 3 tops successively; Plasma reactor 3 is preferably a kind of dielectric barrier discharge plasma reactor, this dielectric barrier discharge plasma reactor is done dielectric barrier with polylith insulated ceramic plates 6, insulated ceramic plates 6 is provided with metallic conductor, is respectively high-pressure side 4 or earth terminal 5.The insulated ceramic plates that is provided with high-pressure side 4 is provided with successively at interval with the insulated ceramic plates that is provided with earth terminal 5, and the insulated ceramic plates that is provided with high-pressure side 4 is 2-5mm with the spacing that is provided with the insulated ceramic plates of earth terminal 5; Distance between the metallic sieve high-pressure stage 1 and the woven wire low pressure utmost point 2 be the high-pressure side 4 of plasma reactor and earth terminal 5 correspondences tight attached insulated ceramic plates 6 spacings 2-2.5 doubly, high-pressure side 4 parallel connections of metallic sieve high-pressure stage 1 and plasma reactor, earth terminal 5 parallel connections of the woven wire low pressure utmost point 2 and plasma reactor; The woven wire low pressure utmost point 2 used woven wire layer thicknesses are 3.5cm, and metallic sieve high-pressure stage 1 adopts the 80-120 eye mesh screen for having the platy structure of screen cloth.
Pending air enters plasma reactor 3, contaminant molecule is decomposed by active particle in the plasma and high energy particle in plasma reactor 3, and airborne partial oxygen molecule also can generate ozone with active particle and high-energy reaction when handling pollutant.Air tail gas after plasma treatment ozoniferous enters between the metallic sieve high-pressure stage 1 and the woven wire low pressure utmost point 2 of dielectric barrier discharge plasma air-treatment ozone treatment device.Because the distance between ozone treatment device two-plate is 2-2.5 times of dielectric barrier discharge reactor two-plate spacing, so the 0.4-0.5 that electric-field intensity is about electric-field intensity between dielectric barrier discharge reactor two-plate between ozone treatment device two-plate doubly, electric field is not enough to cause gas discharge between ozone treatment device two-plate, but can make the charged particle that enters wherein produce acceleration, improve the charged particle energy, charged particle and ozone molecule collision promote the decomposition of ozone molecule, thereby reduce ozone concentration in the tail gas.Simultaneously, the woven wire low pressure utmost point 2 produces certain electric current in circuit behind the certain charged particle of absorption, woven wire can keep higher temperature thus, and the woven wire low pressure utmost point 2 helps increasing the contact area of handling gas and pole plate, the absorption ozone molecule increases ozone and decomposes.
As mentioned above, can realize the utility model preferably.