Discussion on toxicity of lampblack and oil
Smoke eliminator
Bai Taoguang and Zhang Yizheng, Department of Environmental Engineering, Shanghai 704.
1
With the development of economy and the improvement of people's living standards, catering
With the rapid development of industry, the problem of oil smoke and waste gas pollution caused by industry is becoming more and more serious.
More and more prominent. Besides endangering human health, oil fume and waste gas are also harmful to the surroundings.
Public health also has a serious impact. The lampblack became a shadow.
One of the main public hazards affecting air quality.
Oil fume is an edible oil and food heated by high temperature thermal oxidation.
Cracking and Milad reaction produce a large number of volatile substances, including Xu.
Many toxic and harmful ingredients. High temperature heating of different kinds of edible oils
There are more than 200 kinds of decomposition products, mainly aldehydes, ketones, hydrocarbons and fats.
Acids, aromatic compounds and heterocyclic compounds [1].
Oil fume has certain stimulating effect on respiratory tract and lungs. it is reported (that)
Tao: After inhaling oil fume for 3 months, scattered cells appeared in the lungs of mice.
Nodules [2]. Inhalation of oil fume also has obvious influence on human lung function.
The entrant will have symptoms such as cough, chest tightness and shortness of breath, which is also harmful to the respiratory tract.
It has a stimulating effect. Henderson reported in 1976 that lampblack is the nose.
A risk factor for pharyngeal cancer. In addition, the fume exhaust gas has a negative effect on gene mutation,
The harm of DNA damage and chromosome damage has also been reported.
The state attaches great importance to the problem of oil fume and waste gas pollution emitted by catering industry.
1In February, 1995, the State Environmental Protection Agency and the State Administration for Industry and Commerce issued "About"
"Notice on Strengthening Environmental Management of Catering and Entertainment Service Enterprises" stipulates that cities
Operators of urban catering enterprises must take measures to prevent and control lampblack.
Pollution to the living environment of nearby residents; 1996 issued by the State Council.
"People's Republic of China (PRC) air pollution prevention law" article thirty-sixth.
, you must set up a device to collect lampblack and odor to eliminate lampblack.
Air pollution; 1997 "Cooking fume emission standard"
Draft for comments issued; In 2000, the State Environmental Protection Administration issued "Drinking"
Oil fume emission standard-GWPB5-2000; Shanghai in 2002
Measures for the Prevention and Control of Air Pollution in Shanghai, which was implemented on June 65438+1 October1,
The Measures for Governing by Law also clearly stipulates the emission of smoke and dust pollution.
It is also reported that at present, residents in many big cities in China are interested in the catering industry.
Complaints about oil fume pollution have accounted for 40% of environmental pollution complaints. This will do.
It can be seen that the harm of lampblack waste gas is becoming more and more serious, so it is necessary to develop lampblack purification equipment.
Preparations are imminent.
2 flue gas purification equipment
At present, there are mainly the following technologies for treating oil fume and waste gas at home and abroad.
Species: (1) mechanical separation method: using inertial collision principle or cyclone separation.
Use the separation principle to separate and remove the oil fume; (2) Wet treatment method: mining.
Water or other cleaning agents are used to spray through nozzles to form a water film.
The water mist absorbs the oil fume, so that the oil fume is transferred from the gas phase to the liquid phase.
So as to achieve the purpose of purification; (3) Fabric filtration method: oil fume and waste gas pass through.
Excessive fibers and other fabrics are diffused and trapped, thus being removed; (4) Live broadcast
Natural activated carbon adsorption method: using the porous adsorption characteristics of activated carbon to adsorb oil.
Smoke particles; (5) Electrostatic treatment: treat the oil fume with high-voltage electric field.
Due to the attraction of electric field force to charged particles, ions are charged and separated.
Pollutants; (6) Catalyst combustion method: In the process of high-temperature combustion,
Catalysts are used to convert oil fume pollutants into harmless substances.
There are many kinds of oil fume treatment technologies, which are being studied by environmental protection workers.
A lot of work has been done in the development of purification equipment, some of which have applied the above technology.
Oil fume purification equipment based on this technology has appeared in the market and put into use.
Apply.
2. 1 mechanical separation and purification equipment
The oil fume enters the purification equipment from the tangential direction, and due to strong rotation,
Centrifugal force, soot particles are thrown out, accumulated into oil droplets, and then flow downward.
To the bottom. The equipment has the advantages of low investment, low operation cost and no secondary pollution.
Easy dyeing and maintenance management; However, it has great resistance and occupies a lot of land.
Application example of cyclone mechanical separation fume purifier [3]: an oil
Cyclone machinery installed in medium-sized restaurants with relatively high fog emission concentration
The lampblack purifier is equipped with three diesel stoves, and the fan is of back suction type.
After 9 months of operation, the oil removal effect is good, and the measured parameters
As follows:
Air volume: 6615m3/h;
Pressure drop of purifier: 300Pa；;
Greenman blackness of flue gas: Grade 0;
Average purification efficiency: 92%;
Most of the odor is removed (by odor, not by measurement).
2.2 Wet purification equipment
The oil fume particles contact with the water mist and water film sprayed by the nozzle and pass through the nozzle.
Through the inertial collision, retention, diffusion and interaction of particles
Coagulation and so on. Together with the water droplets, the oil fume ions are separated from the airflow.
Separate from it The equipment has the advantages of simple structure, less investment, small floor space,
Low operation cost and convenient maintenance and management; However, there are also some problems, such as large resistance and generation
Shortcomings of secondary pollution of oily sewage. The purification efficiency is generally around 82%.
Wet purification equipment includes water bath, pulse, horizontal cyclone water film,
Vertical cyclone water film, venturi tube, etc.
Application example of wet liquid membrane filtration purifier [4]: a hotel kitchen
Located in the downtown residential area, there are 8 diesel gasifiers in the kitchen.
Every day 150 people eat, and 400~500kg of oil is eaten every month.
Consumption of diesel oil 1000~ 1500kg per month seriously pollutes the surrounding residents.
The technical parameters of the wet liquid membrane filtration purifier installed in this kitchen are as follows:
Flue gas velocity in the air duct:12m/s;
Flue gas velocity: 6m/s;
Nozzle: Select annular liquid film nozzles and arrange them at opposite distances.
20 ~ 30cm
Filter screen: made of metal wire, the mesh size is 0.8×0.8 mm; ;
Dewatering plate: it is in the form of folded plates arranged obliquely, and the spacing between plates is
20mm away;
Fan: the flow rate is16000 ~ 20000m3/h;
The total pressure is 600-750 Pa;
Power 4.5kW；;
Purification efficiency: 82%;
Operating expenses: the electricity fee is 4.2 yuan per hour (calculated by 0.7 yuan per degree);
The liquid absorbent is 0.98 yuan per hour.
2.3 filtration and purification equipment
Oil fume exhaust gas first passes through a certain number of metal grids, which are very large.
Particulate pollutants are intercepted; Then pas through a filter material such as a fib mat, particles
Things are removed by diffusion and interception. Commonly used filter materials
This material is a polymer composite material with high oil absorption performance. This kind of equipment investment
Less, low operation cost, no secondary pollution, convenient maintenance and management; but
Its disadvantages are large resistance, large floor space and frequent replacement of filter media. clean
The chemical efficiency is generally 80 ~ 92%.
Because the resistance of the filter material is great, such as the glass fiber filter material of the purifier
The pressure drop can reach 1500Pa, so it is necessary to change the filter media frequently to make the filtration mode clean.
The application of chemical equipment is limited. While Qiangning [5] and others used filtration method.
Purification equipment has achieved success in treating oil fume.
Application example of filtration and purification equipment [6]: installation in a restaurant in Shanghai
The operation of this equipment is as follows:
Treatment capacity of oil fume waste gas:1116m3/h;
Intake air concentration:18.4mg/m3;
Effluent concentration:1.406 mg/m3; /m3；
Pressure drop of purifier: 372Pa；;
Purification efficiency: 92.3%.
The equipment has good purification effect, and under the condition of not replacing the filter material,
Running for more than 3 months is basically normal.
2.4 activated carbon adsorption purification equipment
Adsorption of soot by granular activated carbon or activated carbon fiber felt
Dye particles. The characteristics of this equipment are similar to those of filtration and purification equipment.
But the effect of removing odor molecules from oil fume is better. The main disadvantage is activity.
Carbon costs more.
2.5 High-voltage electrostatic purification equipment
Under the action of external high voltage, the surface of the negative metal wire
Or that electron released nearby quickly move to the anode and collide with gas molecule.
And ionize. When flue gas waste gas passes through the high-voltage electric field, flue gas particles
In a short time, protons will be charged due to the collision and capture of gas ions.
Under the action of electric field force, electricity moves to the positive dust collecting plate, thus realizing separation.
Separation effect. This equipment has less investment, small floor space and no secondary pollution.
Operating costs (mainly electricity) are low. Because it is easy to catch particles.
Dust with smaller diameter has high purification efficiency, which can reach 85 ~ 95%. its
The purification mechanism is different from other methods in that the separation force is electrostatic force,
It acts directly on particles, not on airflow, so it has
It has the characteristics of low energy consumption and small resistance. The disadvantage is that the structure is complicated,
Cleaning is inconvenient.
Application example of electrostatic fume purifier [7]: A hotel in Hangzhou adopted
The monitoring data of electrostatic fume purification device are as follows.
(monitored by Shanghai Environmental Monitoring Center):
Air intake: 880m3/h;
Intake air concentration: 50.4 mg/m3;
Imported lampblack emission: 0.0398kg/h;
Outlet flow: 810nm3/h;
Effluent concentration: 8.12 mg/m3;
Export lampblack emission: 0.00593kg/h;
Purification efficiency: 85. 1%.
2.6 catalytic combustion purification equipment
The principle of combustion purification method is to use the heat generated by high temperature combustion.
The amount of oxidation reaction, the pollutants in the lampblack waste gas into
CO2 and H2O, so as to achieve the purpose of purification.
In the combustion process, the oil fume waste gas passes through the self-purification catalyst.
(self-cleaning catalyst), the catalytic reaction of the catalyst is beneficial to
Transformation of pollutants. It is reported that Japan has developed a new cooking technology.
The exhaust gas treatment catalyst is mainly composed of low melting point lithium glass.
Bonding γ-MnO _ 2, molecular sieve, ferrite and organic binder
Bonded metal oxide. These catalysts not only have catalytic effect.
In addition, it also has the functions of heat conduction and far infrared emission, which can improve cooking.
Speed and the taste and color of the dishes.
The mature products of this flue gas purification equipment have not been reported in China.
Tao.
3. Development of oil fume purification equipment
With the development of economy and the improvement of people's living standards, more and more attention has been paid to the treatment of oil fume and waste gas.
The improvement of peace and the enhancement of environmental awareness have formed a new kind of environmental protection.
Field. Research on Treatment Technology of Oil Fume and Waste Gas and Development of Purification Equipment
The following factors should be considered: investment, operating cost, pressure drop and energy.
Consumption, maintenance and management, occupied space, purification efficiency, and presence of secondary pollution.
Dyes, etc. Small R&D investment, high purification rate, low energy consumption and less land occupation.
Oil fume purification equipment occupies a small area and is easy to maintain and manage, which is an environmental protection industry.
As a potential demand point of the market, it has broad development prospects.
It is necessary to consider the required high removal rate from the perspective of environmental protection.
Secondary pollution and other factors; We should also consider the expected investment from the perspective of users.
Less, low energy consumption, small area and other factors, obviously, a single cure.
The management method is no longer satisfactory. Future development of fume purification equipment
It is necessary to combine the above basic purification technologies and give full play to their respective roles.
Self-advantage. Such as: the combination of mechanical collision and static electricity, filtration method.
Combining wet method, cyclone separation method and activated carbon adsorption method,
Combination of cyclone separation method with water mist or water film wet method, filtration method and static method
The combination of electric method and activated carbon adsorption method.
In addition, due to the increasing shortage of urban land, many catering industries
Large lampblack households don't have enough space to install huge oil.
Therefore, the flue gas purification equipment adopts oil with small pipeline (horizontal) structure.
Smoke purifiers will be more and more favored by users.
4 Conclusions and suggestions
(1) The purification efficiency of mechanical separation and purification equipment is not high, and it is only suitable for pretreatment.
Where the requirements for treatment or purification efficiency are not high; Wet cleaning device
The purification rate of submicron particles is very low, so it is necessary to produce them.
Treating the washing liquid; Filtration and purification equipment needs to change the filter material frequently.
High energy consumption; The cost of activated carbon adsorption purification equipment is too high; catalytic combustion
The development of combustion purification equipment is not very mature; Electrostatic purification equipment
With its high purification efficiency, small pressure drop, stable operation and convenient maintenance and management.
Convenience and other characteristics show its superiority more and more, and it has a strong market
Domain competitiveness.
(2) Application, investment, operating cost, pressure drop and energy of comprehensive technology.
Consumption, maintenance and management, occupied space, purification efficiency, secondary pollution, etc.
It is the dominant factor that determines the development direction of lampblack purification equipment in the future.
(3) How to ensure high purification efficiency while making the equipment not occupy space?
As small as possible, even does not occupy the floor space (such as installed in flue gas
Pipeline) is a topic that needs to be discussed by environmental researchers.
5 references
[1] Anghopiu. Margaret, source of butter and vegetable oil
Polycyclic aromatic hydrocarbons. American petrochemical company.
Soc， 1986，63: 889~893
[2] Liu Zhanqin et al. Study on the effect of kitchen frying oil fume on the lungs of experimental animals. environment
Journal of Health,1985,5 (5): 34
[3] Xu Fangcheng et al. Experimental study on kitchen fume purifier of swirl catering industry. ring
Environmental Pollution and Prevention, 2000, (4): 12 ~ 13
[4] Liu,, et al. Treatment of kitchen oil fume and fire smoke by liquid membrane filtration. Environmental engineering,
1999.(2):4 1~42
Qiangning develops practical kitchen oil mist purification equipment. Environmental engineering, 1998, 16.
( 1):26
[6] Zheng Xianjue et al. Discussion on cooking fume purification equipment in catering industry. Environmental pollution and prevention,
1999.( 10):23~24
About the author: Bai Tao Guangnan (1976-), assistant engineer, engaged in environmental work.
Design research and product development of pollution prevention engineering in engineering field.