The working principle of washing tower
The washing tower tower is composed of a tower body, plate, reboiler, condenser. As the washing tower is a rough separation equipment, so the number of trays generally less, usually not more than ten. The washing tower is suitable for the separation of mixed gas containing small amounts of dust. The reaction of each component will not occur, and the products should be liquefied easily. Dust and other impurities (also called high boiling substances) are not easy to liquefy or solidify. When the mixed gas washing tower from the middle into the washing tower, due to the presence of the product components of liquid column plate, the product components of gas liquefaction and evaporation, while the impurities cannot be due to liquefaction or solidification, when through plateliquid there will be a product component liquid fixed, produce washing, washing the tower is designed and manufactured according to the principle of.
The washing tower is mainly based on the principle of odor components by using strong acid (sulfuric acid), alkali (sodium hydroxide) and oxidant (sodium hypochlorite) as washing spray solution and odor molecules in the gas contact, the gas odor components transfer to the liquid phase, and with the help of chemical agent and odor component neutralization, oxidation of odor removal material.
The common washing equipment is the packed column, the chemical absorption liquid is sprayed down from the top of the tower, the exhaust gas flows up to the upper level, and the odor is fully contacted and reacted with the absorption liquid so as to be removed. The absorption liquid and the gas flow ratio (liquid / gas ratio) is generally 1-3 L/m fand, filling height is 2-5 meters, gas velocity of empty tower is generally 0.5-1 M / s.. Well packed tower, deodorizing effect can reach more than 90%.
Commonly used chemical absorbents include the following:
(1) alkaline solution;
Alkaline absorption liquid containing 1%~10% sodium hydroxide solution commonly used to remove hydrogen sulfide gas, significant effect, such as methyl mercaptan, methyl sulfide, two methyl sulfide, lower fatty acids, often in wastewater treatment field caused by the smell of the material, treatment effect is also significant.
(2) acid solution
Acid washing is mainly used to remove the odor caused by ammonia, trimethylamine and other basic gases. Generally, sulfuric acid (0.5%-5% solution) is used as washing liquid.
(3) sodium hypochlorite solution;
Sodium hypochlorite is commonly used with a pH absorption solution. Methyl sulfide for other methods is difficult to eliminate the use of sodium hypochlorite solution absorption good control effect. When dealing with high concentration odor, the concentration of sodium hypochlorite solution (effective chlorine concentration) is about 500~2000 ppm; while treating lower concentration odor, the concentration of sodium hypochlorite solution is about 50~500 ppm. In terms of the properties of oxidants, sodium hypochlorite is the cheapest and has good treatment effect, so it is widely used.
In the solution of the sodium hypochlorite (HOCl) form:
NaOCl+ H2O = HOCl+ NaOH...
In pH=7.5, the effective chlorine in the hypochlorite solution is present with 50% HOCI and hypochlorite ions (OCl-);
In pH=l0, only 0.3% of the effective chlorine exists in HOCl;
PH=l1 or 12, HOCl, is almost completely dissociated into useless perchlorate ions, and thus pH values are controlled very seriously.
Washing tower performance characteristics
(1) the washing tower treatment system is cheap and easy to handle;
(2) the vertical structure is most suitable for economic space installation;
(3) applicable to gaseous and liquid pollution sources;
(4) dealing with a single pollution source;
(5) suitable for medium and low air volume;
Scope of washing tower
(1) the treatment of various harmful gases such as H2S, SOX, NOX, HCI, NH3, CI2 and so on;
(2) deodorization device for refuse transfer station and sewage treatment plant;
(3) exhaust treatment of semiconductor optoelectronics industry;
(4) treatment of waste water from the landfill and the waste gas in the storage tank;
(5) disposal of waste gases from incinerators and industrial furnaces.