Abnormal emission of waste gas from cement plant

Date: 2019-08-26 Views:

With the rapid development of our country's economy, the continuous improvement of people's living standard and environment problem increasingly prominent, the state control of the pollutant discharge demand is higher and higher, the administrative punishment is getting heavier and heavier, more and more comprehensive management measures, the previous requirements for prevention and control facilities and management can not meet the requirements of new environmental laws, new countermeasures must be taken to control all the normal and abnormal pollutant discharge, protect the ecological environment.

cement production

1. Abnormal emission of waste gas and pollutants in daily production

 

The abnormal emission of pollutants in the daily production of cement enterprises is large, mainly manifested in 10 aspects:


(1) a large amount of dust is discharged without organization when the hoist is emitting ash;

(2) the cement pipe joints on the top of the cement warehouse leak ash and discharge dust without organization;

(3) the conveying pipe on the top of the cement warehouse blows through and emits ash, and the dust is discharged without organization;

(4) pulverized coal spontaneously ignites in the system, and a large amount of waste gas is discharged without organization;

(5) pulverized coal explodes in the system, and a large amount of waste gas is discharged without organization;

(6) the bag catcher pastes the bag, the pressure in the system is high, and the amount of dust discharged without organization in the system increases;

(7) bags are burned by cloth bag precipitator, which reduces dust removal efficiency and leads to excessive dust emission;

(8) broken bags of cloth bag filter, reduced dust removal efficiency, and excessive dust emission;

(9) when the CO concentration in the exhaust gas of kiln tail reaches the specified value, the electrostatic precipitator is closed, and the exhaust gas is directly discharged beyond the standard without treatment;

(10) corona occlusion occurs in the discharge electrode, dust removal efficiency is reduced, and dust discharge exceeds the standard;

 

2. Causes of abnormal discharge of pollutants in daily production and countermeasures

 

2.1 dust emission of elevator


Reason: dust collector not open;The dust collector and lift the confidential seal is not strict air leakage is serious;Dust catcher block material, paste bag, etc.

Prevention and control measures: should find out the reason, according to the corresponding reasons for treatment, such as dust collector not open need to start the dust motor and dust valve to the appropriate position.

 

2.2 cement pipe joints at the top of cement storehouse leak ash


Reason: transmission pipe flange connection is not good, screw loose, sealing is not strict, or asbestos pad crushed off.

Prevention and control measures: screw tightening or replacement, with asbestos gasket.

 

2.3 the conveying pipe at the top of cement warehouse is blown out and ashes come out


Reason: high wind speed and wear of materials in the process of feeding.

Prevention and control measures: should be in the ash to repair welding or cement asbestos rope soaked in the ash to do temporary remedial, to stop welding, blowing when serious to stop the replacement.

 

2.4 spontaneous combustion of pulverized coal in the system


Reason: coal may be too dry;When the coal mill is running, there is coal dust deposited in the system.Pulverized coal sticks and blocks in the system.

Control measures: coal mill export gas temperature can not be too high;Prevent deposition and blockage of pulverized coal in the system and prevent air leakage;Control coal mill outlet gas temperature is not too low.

 

2.5 pulverized coal explodes in the system


Reason: coal may be too dry;Pulverized coal is very fine, suspended in direct contact with air, ignition explosion.

Prevention and control measures: control coal mill outlet gas temperature should not be too low, prevent moisture condensation in pulverized coal;Control the fineness of pulverized coal at the outlet of coal mill to prevent the operation of coal grinding. Once found, the outlet temperature of coal grinding should be strictly controlled to be less than 80℃, and the coal feeding should be resumed as soon as possible. If the coal cannot be resumed for 10min, the grinding treatment should be stopped.It introduces preheating waste gas, makes the coal mill system operate in the inert state, prevents air leakage, controls operating temperature, prevents and limits the formation of explosible gas, etc.

 

2.6 bag filter paste bag, high pressure in the system


Reason: the shell seal is not good, so that the filter bag is wet by water;Poor ash cleaning;High dust moisture content;The filter bag is not hung correctly.

Prevention measures: replace dry filter bag, strengthen shell seal, or solve water leakage;Strengthen manual ash cleaning, improve ash cleaning device and method;Control the temperature and humidity of imported flue gas, strengthen heat preservation, reduce air leakage, strengthen flue gas treatment;Adjust the suspension.

 

2.7 broken bags of cloth bag remover


Reason: dryer appears "empty burning" phenomenon, high temperature of flue gas.

Prevention measures: the temperature of flue gas should be controlled to ensure that the temperature of flue gas entering the dust collector is below 180℃, or continuous feeding.

 

2.8 broken bag of cloth bag collector


Reasons: too long or too short ash-cleaning cycle;Too loose bag suspension;Excessive filtration wind speed;Friction of filter bag frame;Exhaust gas temperature is too high.

Control measures: adjust the cleaning period;Improve bag quality;Reduce air volume;Trim frame quality or adjust installation;Control inlet gas temperature or replace with high temperature resistant filter bag.

 

2.9 the CO concentration in the exhaust gas of kiln tail reaches the specified value


Reason: if the CO concentration in the exhaust gas reaches the specified value, the CO alarm device will alarm, and the precipitator will not be closed, which will lead to the explosion of the precipitator.

Prevention and control measures: should increase the air supply or reduce the amount of coal added.

 

2.10 corona occlusion occurs at the discharge electrode


Reason: a large number of positive ions exist near the discharge electrode. After the collision between the positive ions and dust particles, the dust particles will be charged and adsorb on the discharge electrode under the action of electric field, resulting in corona occlusion.

Prevention and control measures: blow or rinse the ash on the electrode;Replace smooth round wire and star wire with r-s burr wire, prickly burr wire and fish bone needle wire, etc.Reduced specific resistance of smoke.

 

3. Summary


Cement industry is a high energy consumption, high material consumption industry, its production is relatively extensive, energy saving, consumption reduction space is huge.With the improvement of production technology, the unit consumption index of cement products decreases year by year, but the total material and energy consumption and total pollutant emission brought by cement production in China have not been effectively controlled.From the perspective of long-term development, to reduce the pollution emission of cement industry, it is necessary to strictly implement policies and regulations and accelerate the construction of pollution prevention and control projects of cement enterprises.

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