Boiler Exhaust Gas Composition
The boiler flue gas mainly contains dust, sulfur dioxide, fluoride and so on.
1. Sulfur dioxide and hydrogen sulfide are harmful to life. Sulfur dioxide, 2.26 times heavier than air, is a colorless, smelly, asphyxiating gas. After long-term exposure to 5.23±0.52mg/m3 SO2, the human body will suffer from bronchopneumonia, hepatocellular turbidioma, ocular keratitis lesions.
2. Fluoride is an organic or inorganic compound containing negative fluorine. Similar to other halogens, fluorine forms a single negative anion (F−). Fluorine can form binary compounds with all elements except He, Ne and Ar. The deadly toxin sarin and the drug efavirenz are all belong to the fluoride category.
Treatment Process
Considering the operation cost and safety, the exhaust gas of the boiler in our company is planned to be treated with the core process of "ventilation system (fan, collecting hood and pipeline) + core purification system (double alkali desulfurization tower + wet electrostatic collector)".
Introduction of the Process
1. The flue gas contains dust, fluoride and sulfur dioxide. Double alkali flue gas desulfurization technology use sodium hydroxide or sodium carbonate solution as the desulfurizer. The prepared sodium hydroxide or sodium carbonate solution is washed into the desulfurization tower to remove SO2 in the flue gas to achieve the purpose of flue gas desulfurization. Then the desulphurization product is regenerated into sodium sulfite or sodium hydroxide by the desulphurization regeneration pool and returned to the desulphurization tower for recycling.
2. After the desulfurization tower, spray system can capture the dust particles in flue gas and dust has not been catched will enter the wet electrostatic precipitator. The principle of wet electrostatic precipitator is to apply tens of thousands of volts of DC voltage between anode and cathode line. Under the action of strong electric field, corona layer will be generated around the corona line, and the air in the corona layer will be avalanches ionized, resulting in a large number of negative ions and a small number of positive ions.
This process is called corona discharge. The dust (fog) particles in the electrostatic precipitator collide with these positive and negative ions and they charged. The charged dust (fog) particles move toward the anode due to the action of Coulomb force in the high voltage electrostatic field. After reaching the anode, the charge is released and the dust (fog) particles are collected by the anode which formed into a water film. It is separated from the flue gas by gravity or washing from the upper to the lower liquid tank or absorption tower. After reaching the standard, the flue gas is discharged through the fan pipe chimney.
Characteristics of the Equipment
1. High dust removal efficiency: generally more than 99%, dust concentration of dust collector outlet gas in the number of 10mg/m³, the submicron particles by fine dust effective high classification efficiency.
2. A wide range of air volume: small only 1min number m³, large up to 1min tens of thousands of m³, can be used for industrial furnace gas dust removal, reduce the emission of air pollutants.
3. Simple structure: low operating cost, easy maintenance and operation.
4. High temperature resistance ability: the use of 307 stainless steel, can be run in the high temperature conditions of 200ºC or above.
5. Authoritative certification escort: in line with the ISO management system certification, through the ISO9001 certification. Each equipment before leaving the factory must pass strict quality inspection, meet the environmental protection acceptance standards, quality safety is guaranteed.
