What are the environmental protection equipment for lime kilns
During the lime production process, a large amount of pollutants such as exhaust gas and dust are generated, which have a serious impact on the environment. In order to meet environmental protection requirements, lime kilns need to be equipped with a series of environmental protection equipment. The following is an introduction to common environmental protection equipment for lime kilns.
1、 Dust removal equipment
Bag filter
Bag filter is one of the commonly used dust removal equipment in lime kilns. It captures dust particles in the dusty gas on the surface of the filter bag through the filtering principle, and the purified gas is discharged into the atmosphere. Bag filter has the advantages of high dust removal efficiency, stable operation, and strong adaptability.
Working principle: Dust containing gas enters the dust collector through the inlet, is evenly distributed through the guide plate, and then enters the filter bag chamber. The dust is blocked on the surface by the filter bag, and the purified gas passes through the filter bag and is discharged from the outlet. With the continuous accumulation of dust on the surface of the filter bag, the resistance of the dust collector gradually increases. When the resistance reaches a certain value, the dust cleaning system starts and removes the dust on the surface of the filter bag through pulse spraying and other methods, restoring the dust collector to its normal working state.
Electrostatic precipitator
Electric dust collectors use high-voltage electric fields to ionize gases, producing electrons and ions. Dust moves towards the electrode under the action of electric field force and is collected on the electrode, thereby achieving the purpose of dust removal. Electric dust collectors have the advantages of large air volume, high dust removal efficiency, and low resistance.
Working principle: After the dusty gas enters the electrostatic precipitator, the dust particles in the gas are ionized under the action of a high-voltage electric field. The negatively charged dust moves towards the positive electrode, and the positively charged dust moves towards the negative electrode. Dust gradually approaches the electrode under the action of electric field force and is collected on the electrode. Regularly clean the electrodes and remove the collected dust to ensure the normal operation of the dust collector.
2、 Desulfurization equipment
Wet desulfurization
Wet desulfurization is a common desulfurization method suitable for removing sulfur dioxide from lime kiln exhaust gas. It achieves desulfurization by contacting sulfur-containing exhaust gas with desulfurizing agents (such as lime milk, sodium hydroxide solution, etc.), causing a chemical reaction between sulfur dioxide and desulfurizing agents to produce sulfite or sulfate.
Working principle: After the sulfur-containing exhaust gas enters the desulfurization tower, it fully contacts with the desulfurizer sprayed from the top of the tower. During the contact process, sulfur dioxide reacts chemically with desulfurizers to produce sulfites or sulfates. The purified gas is discharged from the top of the desulfurization tower, and the reacted desulfurization solution enters the circulation pool for treatment or regeneration.
Dry desulfurization
Dry desulfurization is a relatively simple method of desulfurization, which involves spraying desulfurizing agents (such as lime powder, activated carbon, etc.) into sulfur-containing exhaust gas to cause a chemical reaction between sulfur dioxide and desulfurizing agents, thereby achieving the purpose of desulfurization. Dry desulfurization has the advantages of simple equipment, low investment, and low operating costs.
Working principle: The desulfurizer is sprayed into the sulfur-containing exhaust gas through pneumatic conveying and other methods. The desulfurizer reacts chemically with the sulfur dioxide in the exhaust gas to produce sulfite or sulfate. The solid product after the reaction can be collected and processed through equipment such as dust collectors.
3、 Denitrification equipment
Selective Catalytic Reduction (SCR) Denitrification
SCR denitrification is an efficient method that achieves denitrification by reacting ammonia with nitrogen oxides in exhaust gas under the action of a catalyst, producing nitrogen and water. Working principle: Ammonia gas is sprayed into exhaust gas containing nitrogen oxides. Under the action of a catalyst, the exhaust gas undergoes selective catalytic reduction reaction between ammonia gas and nitrogen oxides, generating nitrogen gas and water. Vanadium titanium based catalysts are commonly used as catalysts, which have advantages such as high activity and good selectivity.
Selective Non Catalytic Reduction (SNCR) Denitrification
SNCR denitrification is a relatively simple method of denitrification, which involves spraying a reducing agent (such as ammonia water, urea solution, etc.) into high-temperature exhaust gas to cause a chemical reaction between the reducing agent and nitrogen oxides in the exhaust gas, generating nitrogen gas and water, thus achieving the purpose of denitrification.
Working principle: Inject reducing agent into high-temperature exhaust gas, and within a certain temperature range, the reducing agent reacts chemically with nitrogen oxides to generate nitrogen gas and water. SNCR denitrification does not require catalysts, has simple equipment, and requires less investment, but its denitrification efficiency is relatively low.
4、 Other environmental protection equipment
Waste gas and heat recovery equipment
The waste gas from lime kilns contains a large amount of thermal energy, which can be recovered and utilized through waste heat recovery equipment for preheating air, heating water, etc., thereby improving energy utilization efficiency and reducing production costs.
Noise control equipment
Lime kilns generate certain noise during operation, which can be reduced by installing soundproof covers, mufflers, and other equipment to meet environmental protection requirements.
In order to achieve environmentally friendly production of lime kilns, it is necessary to select suitable environmental protection equipment according to the actual situation, strengthen the operation management and maintenance of equipment, ensure the normal operation of environmental protection equipment, and effectively reduce pollutant emissions.
