2. Large centrifugal fans such as high-temperature fan, raw mill circulating fan, kiln head and tail exhaust fan, grate cooler fan and coal mill exhaust fan are technically transformed into energy-saving centrifugal fans, and energy-saving speed regulation modes such as variable frequency speed regulation are implemented. Generally, the equipment selection in the design of production line is too large, and there is a large deviation between the actual production and the design. The fan does not necessarily operate on the best performance curve, and the efficiency of the designed fan is not high, resulting in low overall operating efficiency. At present, the efficiency of the newly designed new energy-saving fan is relatively high, up to 82-85%; At present, there are traditional variable frequency speed regulation, the latest magnetic couple speed regulation (coupling) , rotor energy feedback speed regulation and other new speed regulation methods (the new technology is more energy-saving and simple in structure than variable frequency speed regulation in theory). At present, most cement enterprises have partially adopted this technology, and few enterprises have completed the transformation. It is suggested that cement enterprises should carry out inspection and evaluation one by one according to the actual situation, and implement them in batches according to the energy-saving effect. At present, the transformation of large fans (including the transformation of motor speed regulation) is the most effective way to reduce the power consumption of clinker process rapidly, and the technology is mature and the investment recovery period is short.
3. Use high-efficiency and energy-saving motor. There are many motors in cement plants, some of which were built earlier. At that time, the motor technology was limited. In recent years, the motor technology has developed rapidly. The former energy-saving and high-efficiency motors have now become ordinary motors. At present, YE4 motors and permanent magnet motors are the most energy-saving motors. The state has also issued three batches of motor elimination lists. It is recommended to replace the obsolete motors in the list with YE4 series energy-saving motors in batches. The motors with frequency conversion, such as powder concentrator motors and cooling tower motors, can retain or upgrade the frequency converter and directly replace them with permanent magnet motors, cancel the reducer, improve the overall transmission efficiency and save energy consumption. Coal ball mills can also be directly converted to large direct-drive permanent magnet motors (vertical mills are also converted to permanent magnet motor drives). After the large motor is replaced by an energy-saving motor, the energy-saving effect is obvious, but the investment is large, and the payback period is generally longer than that of the fan transformation.
4. Use energy-saving air compressor to save electricity. Air compressor is a kind of equipment whose operation and maintenance cost is higher than equipment cost. It is suggested that at least one of them should be changed to frequency conversion type to cope with the fluctuation of gas consumption; At the same time, according to the actual situation of long off-peak shutdown time, it is suggested that at least one air compressor should adopt air-cooled structure. In the period of low off-peak shutdown gas consumption, the circulating water pump of the whole plant can be shut down to reduce the situation that the circulating water of the whole plant is needed to cool the air compressor alone. It is suggested that the compressed air flow meter should be installed on the main pipeline of the air compression station, the control of the leakage of compressed air should be strengthened in daily life, and the change of the unit compressed air power consumption should be analyzed to reduce the power consumption of the air compressor. The investment of this technical transformation is relatively small and the payback period is relatively short, especially when the original equipment needs to be replaced or the amount of maintenance is large, it is recommended to directly replace it with a new type of high-efficiency energy-saving air compressor for improved maintenance.
5. Use energy-saving water pump. Cement plant water pumps are mainly waste heat power generation circulating water pumps, kiln system cooling water circulating water pumps, fire pumps and other high-power pumps. The technical transformation is energy-saving water pumps plus energy-saving motors. After the replacement of waste heat power generation circulating water pumps by some manufacturers, the 250kW power motor is replaced by 160kW power motor. The energy-saving effect is very obvious and the investment recovery period is short. Generally, the investment can be recovered within two years.
6. Transform the primary air fan at the kiln head, two coal feeding fans and other Roots blowers. Generally, there is one primary air fan, and some coal injection pipes require two fans at the kiln head and two coal feeding fans. Generally, there are three Roots fans at the bottom of the raw material homogenization silo, two for operation and one for standby. These Roots fans are transformed into magnetic suspension fans or air suspension fans, which on the one hand reduces the noise on site, and on the other hand can save about 1 kilowatt-hour of electricity per ton of clinker. At present, the technology of magnetic suspension fan and air suspension fan is becoming more and more mature, and the technical performance has its own characteristics. Each enterprise can choose according to the actual situation. This transformation technology is mature, the investment is not high, and it can also reduce noise and improve the working environment of on-site staff. It is recommended to carry out the transformation once or in batches.
7. Reduce the resistance of dust collector at kiln head and kiln tail, and reduce the power consumption of system fan. It is suggested that the negative pressure at the inlet of the bag filter should be controlled within -500Pa, the resistance of the dust collector at the kiln inlet should be controlled to about 1000Pa, and the best level at present can be controlled within 800Pa. If the resistance exceeds 1500Pa, the filter bag should be replaced. The resistance has a great impact on the power consumption of the follow-up fan. At the same time, regularly check the tightness of the dust collector, focusing on the manhole door, shell welds and other parts. In addition, pay attention to check the air leakage at the ash discharge of the dust collector hopper. Use a good quality dividing wheel, or use two layers to open the gate valve alternately, or use the current new technology of the leather curtain valve to strengthen the sealing, and strengthen the daily inspection and maintenance.
8. Reduce the air leakage of the system and the power consumption of the fan. Pay attention to the oxygen content of the preheater and the oxygen content of the chimney at the kiln tail and the difference value to judge the sealing of the kiln head and the kiln tail and the air leakage of the preheater, and if necessary, carry out the sealing transformation of the kiln head and the kiln tail; The air leakage of the vertical mill system can be judged by the difference of the oxygen content of the chimney at the kiln tail of the vertical mill, and the vertical mill system can adopt a sealed small bin and a sealed plate feeder or a novel sealed rotor feeding device to replace the design of an old dividing wheel or a triple valve with large air leakage; Special attention shall be paid to the inspection of the expansion joint of the pipeline, the valve shaft, the weld joint of the steel plate and other parts. By strengthening the management of the air leakage of the whole system and saving the power consumption of the fan, the oxygen content of the kiln tail chimney of the production line of the excellent enterprise can be reduced to less than 5% during the period of stopping the vertical mill; and the oxygen content of the kiln tail chimney is also related to the conversion of the environmental emission data, which is a very important control parameter.
9. Increase the waste heat power generation and reduce the self-consumption rate of waste heat power generation. The normal value of power generation per ton of clinker is between 30 and 35 degrees. If the power generation is low, targeted technical transformation can be carried out, such as the use of new spiral fin heat exchange tubes and the use of dry ice to clean accumulated dust in the boiler to increase the heating power. For the self-consumption rate of waste heat power generation, the current rate of excellent enterprises has been reduced to below 5%, about 4%. It is suggested to adopt water jet air pump transformation, energy-saving water pump transformation, some cooling tower motors can also be changed into water turbines, use residual pressure to drive fans to cool down, no longer consume electric energy and other measures to reduce the rate of self-use electricity.
10. Reduce the power consumption of coal mill. Due to different coal quality, the power consumption of coal mill varies greatly among enterprises at present, but there is also room for optimization. For example, for the vertical mill process of coal mill, the powder concentrator can be transformed to increase the output and reduce the power consumption. It is better to reduce the power consumption of coal mill per ton of raw coal to less than 32 kilowatt-hour. For the ball mill process, it is recommended to carry out the internal transformation of the mill, and it is better to reduce it to less than 42 kilowatt-hour.
11. Reduce the resistance of preheater and reduce the power consumption of high-temperature fan per ton of clinker. High temperature fan is an important power consumer, accounting for a large proportion in tons of clinker. In addition to the use of energy-saving high temperature fan and frequency control of energy saving, through the transformation of preheater and calciner system, the negative pressure at C1 outlet is reduced, and the power consumption of high temperature fan is reduced. At present, due to design and overproduction reasons, the negative pressure at C1 outlet of some production lines reaches negative 7000-8000 Pa. However, the negative pressure at the outlet of the newly designed low-resistance preheater is only more than 4000 Pa, and the negative pressure at the outlet of the newly designed six-stage preheater is only more than 5000 Pa. It is suggested that enterprises without conditions to carry out large-scale transformation should carry out local expansion and micro-transformation of high resistance parts such as smoke chamber necking, cyclone volute size, inlet cross-sectional area, calciner necking cross-sectional area and calciner elbow according to their own process conditions to reduce system resistance; At the same time, pay attention to the oxygen content and carbon monoxide content at the outlet of C1 in the operation, change the operation habits, and reduce the excessive wind.
12. Reduce the power consumption of grate cooler fan group. The grate cooler has many fans. In addition to the use of energy-saving fans and motors, the internal air leakage and cross-flow of the grate cooler shall be reduced, and the power consumption for doing useless work shall be reduced; the air volume and air pressure of the fans in the first few rooms shall be increased as much as possible, the clinker quenching effect shall be strengthened, the secondary and tertiary air temperature shall be increased, and the grate gap shall be paid attention to and regularly cleaned and maintained; The counterweight and vent area of the arc valve under part of the fourth generation grate cooler can be optimized and adjusted.
13. Reduce the power consumption caused by idling and inefficient operation of conveying equipment. In the last two years, with the strict control of environmental protection and overload management, the quality of many materials entering the cement plant is uneven, large materials, sundries, sticky and wet materials occur from time to time, the incoming time is not very stable, and various emergencies increase, resulting in the incoming belt, elevator and other conveying equipment can not run well at full load. Certain technical measures are taken to reduce the no-load and low-load operation time of conveying equipment and save power consumption.
14. Improve transmission efficiency and save power. The traditional driving equipment such as large hoists and belt conveyors are generally driven by hydraulic couplers, which are inefficient and prone to failure. The new magnetic coupler has advantages over the hydraulic coupler in improving transmission efficiency, reducing vibration and adjusting installation accuracy. At present, the magnetic coupler is divided into a variety of structures, each of which has its own advantages and disadvantages, and you can choose according to the situation. Moreover, the unit price of the magnetic coupler is not high, and the magnetic coupler can be replaced in batches at one time or one by one according to the situation.
15. Build energy management center, intelligent operating system, etc., and adopt digital and intelligent ways to save electricity. The energy management center is a management tool, which will not save energy itself, but through data analysis and comparison, advanced benchmarking, it can find the energy waste points and gap points in the system, and ultimately achieve the goal of energy saving by adopting targeted improvement and optimization control of technical and management means. Compared with the traditional manual operation, the intelligent operating system is more accurate and more predictive, thus achieving the effect of optimal unit time and the lowest energy efficiency. After adopting the intelligent operation, the power consumption can generally be reduced by 1-3 degrees.
The above measures can be measured and analyzed by each enterprise according to its own actual situation, and the project with small investment and short payback period can be implemented first; it is suggested that the equipment that needs to be replaced in the cycle should be directly replaced with the latest energy-saving equipment, and this improved maintenance method should be adopted; Through the implementation of the above measures, it is believed that the comprehensive power consumption per unit product of clinker in most cement enterprises can be reduced to below 57 degrees of the secondary energy consumption standard, and some enterprises can reach the energy consumption level below 48 degrees of the new national standard.
In addition, photovoltaic power generation and new energy storage technology are developing day by day, and the price is decreasing. Many cement enterprises have built distributed photovoltaic power stations and energy storage power stations. The industry has also proposed zero-purchase mines and zero-purchase factories. Photovoltaic power generation is the future trend. At present, there are different preferential policies in different places. It is suggested that cement enterprises can choose the right time for construction according to local policies and the conditions of open space, roof, shed roof and other sites. At least, solar power generation on the top of car shed and office building can be built first, and new energy charging piles can be built for employees with energy storage technology to facilitate the charging of electric vehicles and new energy vehicles. The detailed power consumption distribution data of representative enterprises with better ton control
at present are listed below. You can compare the standards with your own units, and then analyze the reasons, carry out targeted benchmarking transformation and optimization to reduce the comprehensive power consumption of clinker.
China Cement Network will be on July 6-7, 2023." The "2023 China Cement Energy Conservation and New Energy Development Conference" was held in Chongqing to jointly explore new ways of energy conservation and consumption reduction in the cement industry from the aspects of energy-saving transformation, application of photovoltaic and energy storage technologies, and transformation of green electricity and alternative fuels to replace traditional energy sources. The meeting
will be followed by a visit to the Eastern Hope < a href = "https://price.ccement.com/pricenewslist-1-500000-0.".
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