According to data research, China's current energy consumption industries are mainly concentrated in the building materials industry, metallurgical industry and chemical industry. Among them, the building materials industry accounts for about 7% of the total energy consumption, and the cement industry in the building materials industry is as high as 75% in terms of energy consumption, and a large amount of CO2 is emitted in the production process, which is not conducive to the implementation of the concept of energy conservation and environmental protection. This requires the introduction of certain energy-saving and emission-reduction technologies to promote the sustainable development of the cement industry.
.Improvement of production processes in the cement industry1.Application of frequency conversion speed regulation technology.
The goal of the application of frequency conversion technology in the production process of the cement industry is to save energy and regulate, and it is typical to use frequency conversion technology to control the power consumption of fans. According to long-term practical studies, it has been found that the power consumption in the production process of 1t cement will reach 100kwh t, and about 30% of the power consumption is used in fan conditioning. Through the application of frequency conversion speed regulation technology to further control the fan, 1kg can be saved in the use of standard coal, and the investment can be recovered after two years of technical use.
2.Application of grinding technology and addition of grinding aids.
In order to achieve the goal of reducing energy consumption, the cement industry commonly uses the final grinding technology of the roller press, which can reduce the power consumption of the product by about 40% on average in the application process, but the general application effect will vary depending on the composition of the cement. At the same time, the vertical mill system in grinding technology also has a certain energy-saving effect, such as the vertical mill system applied by many cement manufacturers in Mexico, with a cement output of 113t h and a surface area of 385 kg, the power consumption of the vertical mill unit is only 187kwh/t。This method is also involved in some domestic cement manufacturers, such as the cement plant of Asia-Pacific Company, compared with the previous application of the coil flow mill, the use of this technology can save 10kwh t in cement. In addition, in terms of the use of grinding aids, according to relevant data statistics, it can save about 4kwh t in grinding power consumption, even if it is difficult to save in cost, but it can play a significant role in reducing the power consumption of cement grinding.
.Focus on the improvement of products and raw materialsIn order to achieve the goal of energy conservation and emission reduction, cement enterprises often add certain mixed materials in the process of grinding materials, which can improve the performance of cement and apply it to actual construction projects. In general, the solid waste residue formed in the steel production or the stone chips and mountain strips present in the mining ore can be selected for mixed materials, which has great potential for energy saving. In addition, in terms of the use of raw materials, the limestone in cement production can also be replaced by industrial waste residue, which can obtain certain energy saving and emission reduction effects. The reason is that many waste slags containing CAO, such as steel slag and slag, are often treated at high temperatures, so that CAO is converted into ferrite or silicate in the form, and the carbon dioxide content is small, and there is no need to heat and decompose again. According to previous practical studies, it is found that in the heat consumption of clinker firing, the energy consumption of CaCO3 in limestone is at least 50%, and calcium substitute raw materials need to be introduced to achieve the goal of energy conservation and emission reduction.
.Reuse of waste materials1.Give full play to the auxiliary role of cement cellar in waste treatment.
In order to make cement waste harmless, the high temperature treatment method is often used for the treatment of cement waste, in which the temperature requirement reaches 1000. In this case, the cement cellar furnace can be applied, which can control the temperature above 1000 in a certain period of time, and make the cement waste meet the requirements of harmless treatment through the calcination of hazardous waste. At the same time, the cement cellar furnace itself also has a certain alkalinity in structure, which can use the neutralization effect to avoid the frequent flow of harmful substances, so that dioxin does not have the conditions for formation. The harmful substances in the general gas will be greatly reduced under the action of high temperature, and the cement production requires salt crystallization, which can reduce the generation of CO2, taking the production of 3000t a cement material as an example, the waste processed after the use of cement cellar is about 10 104t, so that the cement waste is harmless and also achieves the goal of energy saving.
2.Application of low-temperature waste heat power generation technology.
At present, energy conservation in industrial production pays more attention to the reuse of resources, and waste heat can be used in the cement industry. Through the form of waste heat power generation, the electric energy consumption can be reduced and the requirements of cement energy-saving production can be met, such as the flash waste heat technology involved in the power generation system is applied to the flash theory, so that the water heating process uses waste heat to form hot water and steam and complete the diversion process, the flash device will form low-pressure steam after the hot water flows, and the high-pressure steam outlet will absorb all the steam, so that the low-pressure steam and the main steam at the high-pressure steam port work together to become the power of the steam turbine for power generation. Moreover, the low-pressure steam in it will continue to condense after the action to form the boiler water supply. Therefore, the application of low-temperature waste heat technology is an important way to generate hot water and electric energy, which meets the requirements of energy conservation and emission reduction in the cement industry.
.Measures to reduce energy consumption in production facilities(1) Energy saving for the main equipment used in production.
1.Energy-saving measures for three-phase asynchronous motors.
At this stage, China has put forward relevant regulations on the three-phase asynchronous motor used in the production process of the cement industry, requiring that the operating load rate of the application process be controlled to about 80%, and the production efficiency can be improved while running stably. According to the operating state of the crusher in the production of cement industry, the current WDJ6 series of power savers can be selected in terms of motor energy-saving equipment, which can control the three-way bidirectional thyristor to ensure that it is in the conduction state, and adjust the output power and equipment starting current during operation, which has certain advantages of intelligence and automation. At the same time, it can also detect the harmful pulse waves in the line in time to ensure voltage stabilization and achieve the goal of power saving.
2.Energy-saving measures for ball mills.
For the ball mill, a liquid resistance starter can be introduced in terms of energy saving, which can significantly improve the starting performance of the asynchronous motor. The principle of its application is that the mechanical transmission device gradually reduces the distance between the plates until the resistance is 0 under the application of liquid resistance, and starts the motor smoothly. It will not have an impact on the power grid when it is applied, and the number of starts can reach about 8 times in a row, and the operation is relatively reliable and easy to maintain. In terms of energy saving of wound motors, relevant compensation equipment such as static phase inlet can be introduced to achieve the goal of compensating the motor by changing the phase relationship between rotor voltage and current. Because the current in the operation of the motor will be reduced after the application of the compensation equipment, the copper loss of the motor will be reduced, and the energy-saving effect is obvious.
3.Energy-saving measures for wind turbines.
The energy-saving measures of the fan in the cement industry are first of all to choose the liquid resistance starter in the startable equipment, and the static phase inlet in the compensation equipment, which can solve the problem of excessive current in the starting fan and the low power factor in operation. Secondly, in order to make the motor speed regulation more reasonable, the liquid resistance governor that can be manually adjusted or automatically adjusted can be used to effectively control the size of the liquid resistance. Finally, the introduction of motor speed regulation technology enables the peripheral signal to be detected, and the process of exhaust and air supply can be automatically completed and the output air volume can be automatically controlled. In the process of traditional air volume control, air release valve or wind baffle is usually used, which is easy to waste too much electric energy, so the latter two methods can be used to effectively solve the problems existing in the traditional air volume control mode.
2) Energy-saving measures for auxiliary equipment in production.
In the case of low-voltage power distribution systems used in the cement industry, most of them cannot achieve the desired effect in terms of capacitance compensation, and the three-phase load is unstable. In this regard, WBJ capacitance accurate compensation technology can be introduced, which can be combined with subcompensation to accurately compensate the system load while co-complementing each other in the processing process. Compared with the capacitance centralized compensation technology, the application of this compensation technology greatly improves the power factor and reduces the reactive power loss of the line. In addition, the application of the compensation technology pays more attention to local compensation, which can provide the corresponding reactive power at the end of the road, solve the problem of reactive flow in the low-voltage distribution network system, and reduce the line loss.
The application of energy-saving and emission reduction technologies is an important way to promote the sustainable development of the cement industry. In the process of practical application, enterprises are required to face up to the problems that are not conducive to the realization of energy conservation and emission reduction goals in the current production process, pay attention to the improvement of production technology, the application of alternative raw materials, the reuse of waste materials and the reduction of energy consumption of production equipment, etc., so as to promote the common improvement of economic, social and ecological benefits of cement enterprises.
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