A kind of dust collection method
Technical field
The invention discloses a kind of dust collection method, belong to the Environmental-protecting dust-removing technical field.
Background technology
Environmental pollution has badly influenced world climate and has changed, and natural calamity is more and more, more and more serious in recent years, has caused safely grievous injury for various countries' economy, the people's lives and property.
In recent years, the haze weather of China is discussed warmly widely.The arch-criminal who causes haze weather is the particle of PM2.5 one class.
PM2.5 refers to that in atmosphere, diameter is less than or equal to the particle of 2.5 microns, also referred to as entering the lung particle.Its diameter be less than the people the hairline thickness 1/20.Although PM2.5 is content component seldom in the earth atmosphere composition, it has important impact to air quality and visibility etc.Compare with thicker Atmospheric particulates, the PM2.5 particle diameter is little, is rich in a large amount of poisonous and harmful substances and the time of staying in atmosphere is long, fed distance is far away, thereby larger on the impact of health and atmosphere quality.
Reduce dust granules thing content in air, mainly contain at present following mode:
(1) cyclone dust removal, cyclone dust removal are the centrifugal force that utilizes the dust-contained airflow of rotation to produce, the process that particulate pollutant is separated from gas.When dust-contained airflow entered cyclone dust collectors by air inlet pipe, air-flow became circular motion by rectilinear motion.The overwhelming majority of swirling eddy becomes under screw with cylinder along wall, flows towards cone, claims that usually this is outer eddy flow.Dusty gas produces centrifugal force in rotary course, the particle of density greater than gas got rid of to wall, and particle is in case contact with wall, just loses inertia force and leans on the momentum of entrance velocity and downward gravity to fall along wall, enters ash releasing tube.The outer rotational gas flow that rotation descends is drawn close to the deduster center because of conical contraction when arriving centrum, and its tangential velocity improves constantly.When air-flow arrives a certain position, centrum lower end, just with same direction of rotation in cyclone dust collectors by lower convolution on, motion continues to spin.Finally, Purge gas claims that usually this is inward eddy outside the blast pipe ejector.The particle of part collection at large is also discharged thereupon.
(2) bag-type dust, bag-type dust is to utilize sack cleaner (a kind of dry dust removal apparatus), filter bag adopts the filter cloth of weaving or nonwoven felt to become, and utilizes the filtration of fabric that dusty gas is filtered, when dusty gas enters sack cleaner, particle is large, heavy dust, because action of gravitation settles down, fall into ash bucket, contain than the gas of fine dusts by filtrate the time, dust is purified gas by detention.It is applicable to capture tiny, dry non-fiber dust.
(3) electrostatic precipitation, electrostatic precipitation is to utilize high-voltage dc to make airborne gas molecule ionization, produce a large amount of electronics and ion, move to the two poles of the earth under the effect of electric field force, dust granules and the bacterium encountered in moving process in air-flow make it charged, and electrically charged particle divides to opposite pole plate with air-flow under the electric field force effect takes exercises, under electric field action, airborne free ion will move to the two poles of the earth, and voltage is higher, electric-field intensity is higher, and the movement velocity of ion is faster.Due to the motion of ion, interpolar has formed electric current.During beginning, airborne free ion is few, and electric current is less.After voltage was elevated to certain numerical value, near the ion discharge electrode had obtained higher energy and speed, and when they clashed into airborne neutral atom, neutral atom can resolve into positive and negative ion, and this phenomenon is called air ionization.After air ionization, due to chain reaction, number of ions in the interpolar motion increases greatly, the electric current (being referred to as corona current) that shows as interpolar sharply increases, air has become conductor, high strong voltage is caught subsidiary bacteria particles, and instant conductive punctures the cell membrane that is comprised of protein, reaches kill bacteria absorption dedusting.
The extensive use the most of above-mentioned each dust collection method, adopting above-mentioned dust collection method is 30-40% for the PM10 clearance, and is only 10% left and right for the clearance of PM2.5, obviously can not effectively remove the PM2.5 dust granules.
Summary of the invention
Technical problem to be solved by this invention is to provide a kind of novel dust removing method, and this dust collection method can effectively be removed the PM2.5 dust granules.
In order to reach above-mentioned skill purpose, technical scheme of the present invention is: a kind of dust collection method comprises the following steps:
(1) by blower fan, waste gas is delivered to atomizer.
(2) in atomizer, with waste gas and atomized liquid mixed aerosol, produce the drop of absorption dust, control liquid-drop diameter at 30-60 μ m, controlling gas liquid ratio is 1.5 ‰-3 ‰.
(3) waste gas after above-mentioned atomizing is passed into gas-liquid whirlwind separator, control the speed of waste gas in gas-liquid whirlwind separator at 20-30m/s, by gas-liquid whirlwind separator with the drop centrifugation out.
(4) drop of separating is delivered to the sewage collecting treatment system.
If EGT is too high, when waste gas atomized in atomizer, atomized liquid easily gasification became minimum drop, is difficult for centrifugation, affects dust removing effects.Can add the waste gas pre-treatment step this moment between described step (1) and step (2): waste gas is delivered to heat exchanger, waste gas is cooled to below 80 ℃.
The key technology point of the inventive method is:
To the control of liquid-drop diameter, make it effectively adsorb dust when (1) atomizing;
To the control of gas liquid ratio, be conducive to form the drop of suitable size when (2) atomizing, improve adsorption effect.
The present invention can effectively remove the PM2.5 dust granules effectively by said method, has reached the purpose of knowing dust in waste gas.The drop of said method separable 90% left and right in gas-liquid whirlwind separator, remaining drop relies on gravitational settling in interference-free large space, and after processing through said method, PM2.5 dust granules clearance can reach 98%.
Description of drawings
The present invention is further detailed explanation below in conjunction with the drawings and specific embodiments.
Fig. 1 is the flow chart of dust collection method of the present invention.
The specific embodiment
Dust collection method of the present invention as shown in Figure 1, concrete steps are as follows:
(1) by blower fan, waste gas is delivered to atomizer.
If EGT is too high, before passing into atomizer, waste gas carries out pretreatment: waste gas is delivered to heat exchanger, waste gas is cooled to below 80 ℃.The purposes that can be used for other through the heat of heat exchanger exchange.
(2) in atomizer, with waste gas and atomized liquid mixed aerosol, produce the drop of absorption dust, control liquid-drop diameter at 30-60 μ m, controlling gas liquid ratio is 1.5 ‰-3 ‰.
The liquid-drop diameter of 30-60 μ m can adsorb the dust of 1-10 μ m effectively, or even the dust of 0.5 μ m.If drop is less than 30 μ m, centrifugal separating effect is poor, if drop will make atomizing inhomogeneous greater than 60 μ m, finally all can affect the collecting effect of dust.
Gas liquid ratio is controlled at 1.5 ‰-3 ‰, drop and the volume ratio of waste gas, i.e. drop (volume) that gas liquid ratio refers to atomize and forms: waste gas (volume)=1.5-3:1000.If gas liquid ratio is lower than 1.5 ‰, because drop is few, the weak effect of absorption is if gas liquid ratio higher than 3 ‰, because drop very easily is condensed into large drop too much, affects collecting effect.
The gas liquid ratio of water mist dust-removing of the prior art or water curtain dedusting is larger, not only affects the dust collection effect, and produces a large amount of waste water.
(3) waste gas after above-mentioned atomizing is passed into gas-liquid whirlwind separator, control the speed of waste gas in gas-liquid whirlwind separator at 20-30m/s, by gas-liquid whirlwind separator with the drop centrifugation out.
Speed in gas-liquid whirlwind separator is controlled at 20-30m/s, matches with above-mentioned droplet size, gas liquid ratio, and the speed in gas-liquid whirlwind separator is during greater than 30m/s, and the 30-60 μ m drop of formation is easily pulverized, and becomes than droplet, is difficult for centrifugation; Speed in gas-liquid whirlwind separator is during less than 20m/s, and the easy polymerization of drop forms larger drop, is unfavorable for centrifugation, affects the dust collection effect.
(4) drop of separating is delivered to the sewage collecting treatment system.Pass into the sewage collecting treatment system through gas-liquid whirlwind separator centrifugation drop out and collect and process, after processing through said method, PM2.5 dust granules clearance can reach 98%.
Above-described embodiment does not limit the present invention in any way, and every employing is equal to replaces or technical scheme that the mode of equivalent transformation obtains all drops in protection scope of the present invention.