Technology of sludge treatment in cement kiln
Date：2019-08-22 16:42 Source：cementepcViews:
According to the current industrial technology level and development trend of our country, cement kiln co-processing sludge is the best way to dispose sludge.In the future sludge cement kiln treatment will be the main treatment of sludge treatment in China.
1. Significance of sludge treatment
If the sludge is not treated in time, it will lead to a large quantity of sludge in the sewage treatment plant overstock, which may lead to the total paralysis of the sewage treatment system, which will make years of efforts to control the river pollution in vain.Therefore, the construction of sludge treatment and disposal facilities is an essential part of urban infrastructure construction and an important environmental protection project that concerns thousands of households.
2.Current situation and process route of cement kiln collaborative treatment
2.1 current status of sludge treatment
The traditional sludge treatment methods mainly include land use, landfill and incineration, etc. With the improvement of environmental standards, the traditional methods cannot meet the requirements of environmental protection.Sludge disposal is developing towards harmless, reduction and resource utilization.Using cement kiln to treat sludge is an economical and feasible resource treatment method.
Experimental results show that the cement kiln together the best way of adding the sludge disposal of sludge for dosing of decomposing furnace, sludge biggest dosing amount should be controlled in 6% cement rotary incinerator under normal operation conditions, material in the furnace temperature is 1450 degrees Celsius, the material stay time 30 to 40 minutes in the oven, flue gas generated in combustion in the furnace temperature higher than 1300 degrees Celsius area residence time is greater than 4 seconds.The sludge in the kiln can be fully burned, the incineration rate can be 99.999%, dioxins and other organic pollutants are completely decomposed.
2.2 disposal plan
There are generally two ways to dispose waste in cement kilns:
One is added from raw mill ingredients.General inorganic wastes, such as fly ash and slag, are disposed by this method. Its advantage is that the raw material homogenization ingredients can be controlled and the influence on the clinker firing system is small.However, due to the high temperature inside the raw material mill (about 200℃), the volatilization of organic pollutants in sludge may be caused, so the addition of raw material ingredients has not been widely used.
The second is added from the preheater decomposition furnace.Although this disposal scheme has some adverse effects on production, it is suitable for the disposal of materials containing organic pollutants, especially volatile organic pollutants.Because the sludge contains certain volatilization, it is selected to add from the preheater decomposing furnace. At the same time, considering the fast gas velocity above the shrinkage opening of the smoke chamber, the sludge addition point above the shrinkage opening of the smoke chamber is finally selected.
Sludge from the end of the kiln smoke chamber into the cement rotary kiln, gas (>800℃) residence time is more than 20s, can completely ensure the sludge in the organic pollutants completely combustion and decomposition.Under the condition of the high temperature of cement kiln, the organic pollutants in the sludge rapidly evaporating and gasification and high temperature air and high temperature, high fineness, high concentration and high adsorption, high uniformity distribution of good contact with alkaline materials, effectively inhibit acid emissions, makes the SO2 and Cl and differentiation of organic chemistry synthesis of inorganic salts.
The raw sludge produced by the water treatment plant is loaded by the car into the cement factory and poured into the closed sludge storage bin. At the same time, the odor in the sludge storage bin is discharged through the pipeline to the fan inlet of grate cooler, which is discharged into the rotary kiln for internal combustion.Sludge enters the feeding end of paste pump through the feeding gate and frequency conversion feeding spiral, and under the extrusion of the two plungers of paste pump, continuously enters the sludge conveying pipeline, and is uniformly fed into the high-temperature area of the furnace chamber through the feeder in the middle of the furnace for combustion.The adjustment of conveying capacity can be realized through the speed of feeding screw and the flow adjustment of paste pump.All the controls are controlled by PLC microcomputer, and can be connected with the kiln control system. The sludge conveying volume can be adjusted remotely and stepless, and the whole conveying process can be unattended.
3. Advantages of cement kiln collaborative sludge treatment
The landfill and compost treatment of sludge need to occupy a large number of land, and there are secondary pollution risks and geological risks.Special construction of incinerators has high investment, high energy consumption, and will produce fly ash, slag and other hazardous waste, harmful gas is difficult to be completely decomposed.By contrast, the technology of cement kiln co-processing sludge has many advantages in terms of harmlessness, comprehensive utilization of resources and economy.
(1) It is finally converted into cement clinker products, without waste left behind;
(2) Cement kiln has large heat capacity, high temperature and stability, which can completely eliminate harmful gas and deal with sludge in large quantities;
(3) No occupation of land resources;
(4) Make full use of primary energy and resources;
(5) Less investment and short construction period.
According to the current industrial technology level and development trend, cement kiln collaborative treatment of sludge is the best sludge disposal approach, environmental protection and cement industry has also given great attention, now some cement enterprises are actively discussing the accumulation of operating experience.In the future sludge cement kiln treatment will be the main treatment of sludge treatment.For more information about cement production line, please consult our customer service or leave a message. We will reply to you as soon as possible.