We may as well start from the motor system design, motor selection, speed control mode and other links, vigorously apply new technology and new achievements to promote energy saving and consumption reduction of enterprises.
1、 Optimize design and pay attention to details
The design of the general layout and process of cement production line is a decisive link. In order to meet the process requirements, plant traffic and equipment maintenance space requirements, the process flow should be simple and the layout should be compact, so as to reduce the loss of various management and circuits, and achieve the purpose of energy saving. In the process of promoting energy-saving work in cement industry, energy-saving design is the key, and optimization design of motor system is the source of energy-saving of motor system, which must be paid attention to.
2、 Transform old motor
The transformation of the old motor mainly adopts the way of replacing the external fan of the motor. The external fan of the motor is changed to the energy-saving type. For different types of motors, there are corresponding energy-saving fan products to choose from. It is mainly used for 2-pole and 4-pole motors running in unit direction. After modification, the efficiency can be increased by 1.35% - 2.55%. Or magnetic slot mud can be used to replace the original slot wedge, and the magnetic slot mud can reduce the core loss and additional loss of the motor, and improve the efficiency. Although the starting torque will be reduced by 10% - 20%, it is very suitable for no-load or light load start-up motor transformation.
3、 Using frequency conversion, speed regulation and energy saving
Energy saving of frequency conversion speed regulation on fan and water pump
Most of the equipment in most cement plants, especially some high-power equipment, are under load most of the time in the production process. In the production process, the mechanical adjustment method is used to adjust the opening angle of wind deflector or valve to meet different air (water) consumption.
The disadvantages of this operation mode are:
(1) High speed of motor, fan or water pump, heavy load intensity and serious waste of electric energy;
(2) The automation degree of equipment operation is quite low, almost entirely by manual adjustment, the adjustment accuracy is poor, and the control is not accurate;
(3) The electric control adopts direct or step-down start-up, the current impact on the grid is large, the power supply (grid) capacity is large, and the power factor is low.
(4) When starting, the mechanical impact is large and the service life of the equipment is low;
(5) Noise, dust pollution and so on.
At present, the main cement plants are raw mill exhaust fan, kiln tail gas treatment fan, Roots fan, cement mill exhaust fan, coal mill fan, castor cooler fan, powder concentrator, circulating water pump, feed water pump, etc. Because the basic principle of variable frequency speed regulation technology is that the motor speed is proportional to the input frequency of the working power supply, the energy-saving effect of the fan water pump using frequency conversion speed regulation is very obvious.
? replace traditional speed regulation with frequency conversion speed regulation
The traditional speed regulation methods such as thyristor cascade speed regulation, DC speed regulation, electromagnetic slip speed regulation, hydraulic coupling speed regulation and asynchronous motor variable speed regulation have the disadvantages of low transmission efficiency and difficult maintenance. However, the results of frequency conversion speed regulation are simple, stable and reliable, with high speed regulation precision, large starting torque and wide speed range. Therefore, the use of frequency control in improving the mechanical transmission efficiency can save about 20%.
Application of frequency conversion in air compressor
The constant pressure air supply of air compressor uses frequency converter and pressure control to form a closed-loop control system, which can reduce pressure fluctuation by 1.5%, reduce noise and vibration. Ensure the service life of the equipment. After using the frequency converter, the air compressor can be started at will under any pressure, which breaks the previous stipulation that starting with pressure is not allowed, and the starting current is greatly reduced. Through the example of using frequency converter, the power saving rate of most compressors is about 20%.
It is an ideal speed control mode because of its remarkable power saving effect. It not only improves the efficiency of the equipment, meets the requirements of the production process, but also greatly reduces the maintenance and repair costs of the equipment. In addition, when the frequency conversion speed regulation is adopted, the inherent DC reactor of the frequency conversion device can improve the power factor and save the capacity for the power grid. The direct and indirect economic benefits are very obvious.
4、 Improve process and reduce energy consumption of motor
There is a big difference in power consumption between advanced and backward cement production technology. According to the report of China building materials daily on October 18, 2005, China's advanced cement enterprises consume 65 kwh of power per ton of cement, some of which reach 55 degrees, while those with backward technology can even consume 120 kilowatts per ton (130 degrees for producing high-strength cement). Therefore, it can be estimated that the power saving space of cement enterprises is between 45% and 55%. In order to save electricity by improving cement production process, the following measures can be taken:
?In this way, the main raw materials such as lime before entering the raw mill can be fully finely crushed, and the closed screening equipment is added to reduce the particle size of the materials into the mill to the "optimal economic feeding particle size", and the power consumption will be greatly reduced. According to this treatment, the output of 300 t / D new dry process production line of Guangdong Sihui Junma company has increased from about 200 t / h to 266 T / h, saving more than 10% of electricity. According to statistics, the total investment of the project is only one item of power saving, and the whole investment can be recovered within half a year.
? change the proportion of grinding bodies of various specifications in the mill.
Generally, each bin of cement mill is equipped with grinding body according to 3-5 specifications. Under the guidance of experts, cement enterprises can: (1) change the proportion of grinding machines of various specifications; (2) adjust the filling rate of grinding body; (3) by changing the shape of working face of lining plate of grinding body, obvious power saving effect can be achieved (power saving up to 5%).
? improve the production process, improve the production capacity of the main engine, and increase the effective utilization rate of auxiliary equipment.
In this way, the installed capacity of auxiliary equipment can be reduced, that is, the process can be improved reasonably, the auxiliary equipment can be reduced by 15% - 45%, and the power can be saved by 10% - 25%.
?adopt new grinding equipment and technology.
For cement enterprises with aging equipment, new grinding equipment and technology can be used. For example, the new grinding production line developed by Chengdu building materials industry design and Research Institute, etc., with a diameter of 3x11 m, the average unit hour output of the mill reaches 60 t, and the system power consumption is less than 28 kW · H / T; for example, the mill and grinding technology newly developed by Beijing molichi cement grinding technology research center, the power consumption of producing 42.5 grade cement is reduced from 45-50 kW · H / T to 25-30 kW · H / T, and the utilization rate of raw materials is close to 1 Each ton of cement can save about 20kw · H / T electricity.
We should vigorously promote the production (supply) of bulk cement and reduce the process of cement bagging.
In this way, the power consumption of packaging equipment and conveying device after packaging can be reduced, and a certain amount of electric energy can be saved. At the same time, it is also conducive to reduce the dust pollution caused by packaging cement and protect the health of workers.
