Comprehensive treatment plan for dust removal, desulfurization, and denitrification in lime kilns
Lime kilns, as one of the important facilities in industrial production, pose a serious threat to the environment and human health due to the exhaust emissions generated during the production process. Dust, sulfur dioxide (SO2), and nitrogen oxides (NOx) in exhaust gases are the main pollutants. Therefore, developing an effective dust removal, desulfurization, and denitrification plan is of great significance for achieving green production in lime kilns.
1、 Dust removal plan
Dust removal is the primary step in the treatment of lime kiln exhaust gas, with the aim of removing dust particles from the exhaust gas and reducing the burden on subsequent desulfurization and denitrification equipment. This plan adopts an efficient bag filter as the dust removal equipment, which has the characteristics of large processing air volume, high dust removal efficiency, and stable operation.
Dust collector selection
According to the characteristics and emission requirements of lime kiln exhaust gas, high-efficiency bag filters that are resistant to high temperature and corrosion are selected. The filter bag is made of synthetic fiber filter materials such as PPS and PTFE, which have good high temperature and corrosion resistance and can meet the high temperature and high corrosion working environment of lime kiln exhaust gas.
Working principle of dust collector
The bag filter mainly consists of an air inlet, a filter bag room, a cleaning system, and an air outlet. Dust containing gas enters the filter bag room from the air inlet, and the dust is trapped on the surface of the filter bag to form a filter cake. The purified gas is discharged from the air outlet. When the dust on the surface of the filter bag accumulates to a certain extent, start the dust removal system to clean the filter bag and restore its filtration performance.
Design parameters of dust collector
The design parameters include processing air volume, filtering air speed, filter bag material and specifications, etc. The processing air volume should be determined based on the exhaust gas emissions from the lime kiln, and the filtration air speed is generally controlled within the range of 0.8-1.2m/min. The specifications of the filter bag are determined based on the processing air volume and filtering area, ensuring that the dust collector can meet the treatment needs of the lime kiln exhaust gas.
2、 Desulfurization scheme
Desulfurization is a key link in the treatment of lime kiln exhaust gas, aiming to remove sulfur dioxide (SO2) from the exhaust gas and reduce its pollution to the environment. This scheme adopts wet desulfurization technology, which has the advantages of high desulfurization efficiency and stable operation.
Selection of desulfurization technology
The emission of SO2 in the exhaust gas of lime kilns is large and the concentration is high, and the use of wet desulfurization technology has significant advantages. This plan uses the limestone gypsum method as the desulfurization technology, and through the chemical reaction between the sprayed absorbent (limestone slurry) and SO2 in the exhaust gas, sulfate and water are generated to achieve the purpose of desulfurization.
Composition and working principle of desulfurization system
The wet desulfurization system mainly consists of an absorption tower, a circulating pump, an oxidation fan, and a gypsum dewatering system. After the exhaust gas enters the absorption tower, it comes into full contact with the absorbent (limestone slurry) sprayed from the top of the tower. SO2 reacts chemically with the absorbent to form calcium sulfite (CaSO3). Calcium sulfite is oxidized to calcium sulfate (CaSO4), also known as gypsum, under the action of an oxidation fan. The circulation pump circulates and sprays the slurry at the bottom of the absorption tower into the tower, maintaining a stable slurry concentration inside the tower. The gypsum dewatering system dehydrates the generated gypsum to obtain qualified gypsum products.
Preparation of desulfurizer and design of desulfurization tower
Select high-quality calcium oxide as a desulfurizer to prepare an appropriate amount of high-quality calcium oxide powder. To ensure the desulfurization effect, regular quality testing of calcium oxide powder is required to ensure its quality. Design a reasonable desulfurization tower structure to ensure that the flow rate and residence time of the flue gas inside the tower meet the requirements of the desulfurization reaction. At the same time, measures such as anti-corrosion and wear prevention inside the tower should be considered to improve the service life of the desulfurization tower.
3、 Denitration scheme
Denitration is another important aspect of lime kiln waste gas treatment, aimed at removing nitrogen oxides (NOx) from the waste gas and reducing its pollution to the environment. This plan adopts selective catalytic reduction (SCR) technology, which uses a catalyst to reduce NOx in the exhaust gas to harmless nitrogen (N2) and water.
Selection of denitrification technology
SCR technology has the advantages of high denitrification efficiency and strong adaptability, and is suitable for the denitrification treatment of lime kiln exhaust gas. Select appropriate catalysts to ensure their good activity and stability in high-temperature and highly corrosive working environments. Composition and working principle of denitrification system
The denitrification system mainly consists of a reactor, catalyst, ammonia supply system, etc. After the exhaust gas enters the reactor, it undergoes a chemical reaction with ammonia under the action of a catalyst, reducing NOx to N2 and water. The ammonia supply system is responsible for providing an appropriate amount of ammonia to the reactor to ensure the smooth progress of the denitrification reaction.
The comprehensive treatment plan for dust removal, desulfurization, and denitrification in lime kilns includes three stages: dust removal, desulfurization, and denitrification. By adopting advanced process technology and equipment, effective treatment of lime kiln exhaust gas is achieved, reducing environmental pollution, improving the quality of lime, and achieving green production. At the same time, this plan also considers the stable operation of equipment and the reasonable disposal of waste, ensuring the sustainability and stability of the treatment effect.
