Technology upgrading and transformation can rapidly reduce energy consumption in cement production process
Date：2019-08-26 14:58 Source：cementepcViews:
According to the current national trend of increasingly strict control of high energy consumption industries, it is urgent for cement enterprises to further reduce the energy consumption of each process.
At present, the advanced indexes of cement industry are as follows:
The power consumption of raw material grinding process is less than 14 KWH/ton, the power consumption of clinker calcining process is less than 23 KWH/ton, the standard coal consumption of clinker is less than 98 kg standard coal, the power generation of ton of clinker is more than 40 KWH/ton, and the power consumption of 42.5 cement grinding process (85% clinker ratio) is less than 29 KWH/ton.
However, many enterprises in the industry do not reach this target, so some enterprises are reluctant, also can not sit idly by.Design institutes and institutes have been sought to calibrate and optimize production conditions.In view of the current domestic mature technology, small series summary is as follows:
1. Raw material grinding process
At present, we basically adopt roller vertical mill, but the biggest drawback of roller vertical mill is that it relies on wind power to lift materials inside the mill, which is the process with the lowest efficiency to improve materials. At the same time, in order to ensure the lifting of materials inside the mill, the main circulation fan of the vertical mill is forced to increase the design, resulting in high power consumption.
How to improve:
Seek the design institute, adopt roller drying and grinding technology, make maximum use of the original elevator, ash return system, exhaust gas treatment system and batching station system, add roller locomotive frame and add powder separator and material circulation system.Under the standard control of 80 micron sieve residue, the power consumption of raw material grinding should be lower than 14 KWH per ton of raw material.
2. Clinker calcining process
2.1 power saving measures
(1) immediately arrange to calibrate and reform the grate cooler fan, primary fan, kiln head exhaust fan, coal mill fan, coal feed fan and high temperature fan of the firing system, which can save at least 10% of electricity;
(2) immediately calibrate the burning system, check the large heat dissipation of the body, and conduct external insulation treatment on the first-level and second-level cylinders and pipes of the preheater, which can improve waste heat power generation by 120-200kwh per hour;
(3) check the thermal calibration. For example, if the proportion of primary wind is more than 7% of the total amount of incoming kiln wind, frequency reduction treatment should be carried out for the primary fan;
(4) check the thermal calibration. If the air leakage rate of the system is more than 2% or the oxygen content of the exhaust gas of the preheater is more than 4%, it indicates that the system is air leakage.
2.2 measures to save coal
(1) improve batching and calcining, and increase the compressive strength of clinker to over 56 mpa for 28 days;
(2) according to the thermal calibration, if the thermal efficiency of grate cooler is less than 72%, it is suggested to carry out renovation, upgrade the fourth-generation grate cooler, and choose a well-reputed grate cooler or a guaranteed brand such as Smith;
(3) check the thermal calibration or central control parameters. If the secondary air temperature into the kiln is lower than 1150℃, the operation needs to be improved or reformed to ensure efficient heat recovery of grate cooler;
(4) check the thermal calibration or central control parameters. If the clinker temperature of grate cooler is greater than 115℃, it is necessary to improve the air operation of grate cooler or carry out renovation to ensure efficient heat recovery of grate cooler;
(5) according to the thermal calibration or laboratory data, the decomposition rate of materials into the kiln of the decomposition furnace should be controlled between 88-93%; otherwise, the efficiency of the decomposition furnace is insufficient or over-decomposition will also lead to the increase of coal consumption;
(6) seek assistance from the design institute to introduce waste heat from kiln head and coal grinding waste gas into grate cooler to cool the air source, reduce waste heat waste, and improve the second and third air temperature of grate cooler.
(1) adopt cooling water with better water quality to improve condenser efficiency;
(2) whether the design of double-superheater of kiln head boiler can be adopted to improve the steam temperature and pressure based on the analysis of the original design;
(3) check the efficiency of auxiliary equipment, adopt high-efficiency equipment when necessary, reduce the self-use electricity of power generation system, and control the advanced level of self-use electricity rate below 6%.
4. Cement grinding process:
(1) seek the assistance of the design institute to upgrade the pre-grinding process of roller press to the combined grinding process, and introduce V waste gas into the separator for particle classification.The roller press out of three categories: back - roll material, abrasive material, finished material.
(2) some cement enterprises still adopt the grinding tail mixing process, which will lead to increased cycle load of ball mill, increased load of powder separator, and virtually increased power consumption.It is necessary to improve the mixing machine process before storage.
(3) to reduce gas lifting pump, chute and other energy-consuming equipment, use rubber belt hoist and closed rubber belt conveyor and other power-saving equipment.
(4) the compressed air pipe network of the system adopts constant pressure frequency conversion control to reduce energy consumption of air compressor.
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