In 2005, Hai'an County, Jiangsu Province, had reduced its energy consumption per 10,000 yuan of GDP to 0.7 standard coal equivalent, placing it among the leading counties in China. This article introduces two examples and their corresponding challenges. 1. Lessons Learned The first example is a textile factory, and the second is a machinery factory. In 2006, both factories achieved sales exceeding 600 million yuan. They possessed a relatively complete management structure, including a scientific quota-based reward and punishment system, and adopted advanced technologies to upgrade traditional equipment, continuously reducing electricity consumption. The textile factory invested 1.623 million yuan in energy-saving upgrades, resulting in annual electricity savings of 2.618 million kWh and 1.5971 million yuan in electricity costs, recovering its investment in one year and two months. The machinery factory invested a total of 2.82 million yuan in energy-saving technological upgrades during the "10th Five-Year Plan" period, resulting in annual electricity savings of 3.7948 million kWh and 1.8132 million yuan in electricity costs, recovering its investment in one and a half years. The technical upgrade of the two plants saved 6.4128 million kWh of electricity per year, which is equivalent to the power plant burning 2,300 tons of standard coal less and reducing CO2 emissions by 2,600 tons, thus contributing to the reduction of air pollution. 1.1 Application of frequency converters (1) Application in fans The textile factory has 16 blower fans and 14 floor exhaust fans, with a total installed capacity of 826 kW and an average load rate of 64%. The machines are run for 24 hours a day and 295 days a year. Before the upgrade, the annual electricity consumption was 3.743 million kWh. After the upgrade, the electricity saving rate reached 25% to 28%. Based on the electricity saving rate of 25%, the annual electricity and electricity cost savings are 571,000 yuan. The total investment in equipment upgrade is 407,000 yuan. The investment payback period is 9 months. If loan interest and depreciation are included, the investment payback period is no more than one year. A fan is a general-purpose machine that converts the mechanical energy input by the prime mover into fluid energy. Generally, fans with exhaust pressure less than 9806.6 Pa are called ventilators; those greater than 9806.6 Pa but less than 98066 Pa (10mH2O) are called blowers; and those above 98066 Pa are called compressors. The blowers and floor exhaust fans used in this textile factory, based on their exhaust pressure, are all considered fans. Ventilators are square torque loads, with relatively small load torque at low speeds, so ordinary function frequency converters can usually be selected. The company's choice of the Senlan SB series frequency converter is reasonable. Based on the characteristics of fans and pumps, when controlled by speed n, the relationship between their flow rate Q, pressure P_a, and shaft power P_N follows the following proportional law: From the above formula, it can be seen that the flow rate is directly proportional to the speed, the air pressure is directly proportional to the square of the speed, and the shaft power is directly proportional to the cube of the speed. Therefore, since speed control can significantly reduce shaft power compared to flow control, using a frequency converter drive instead of valve control can fully save electricity. For valve control equipment that has been put into operation, the valve can be turned to the maximum (fully open), and the speed control of the frequency converter can achieve a significant energy saving effect. The fans in the textile industry are used for cooling and humidifying the workshop. Due to seasonal changes and changes in environmental humidity, the required air volume varies greatly. Except for summer, the air supply is generally small in general seasons. Haian is located in the lower reaches of the Yangtze River and is close to the Yellow Sea. The humidity is highest in July to September every year. The fans need to run at full speed to ensure the air volume required for production. Therefore, the frequency converter is taken out of operation during these three months. Haian is coldest in December, January and February every year. The air volume required in the workshop is small. The fans run at low speed through the frequency converter. This month, a significant energy saving can be achieved. In other months, the air volume required in the workshop is moderate. The AC frequency of the frequency converter is generally adjusted to about 30Hz to save a lot of electricity. Since the fan has a resonance point at a certain frequency, attention should be paid to using the frequency jump function of the frequency converter. (2) Application in water pumps The textile industry regulates the temperature and humidity of the workshop by water spraying and air heat and humidity exchange. The water consumption is relatively large. Due to seasonal changes and climate variations, water consumption is not constant. In the past, valve control was used to regulate water consumption, which not only wasted a lot of electricity, but also caused the pressure of pumps, pipes and other equipment to change constantly due to frequent valve adjustments. In particular, the pressure in the system increased after the valve was closed, and this repeated cycle led to a high rate of equipment damage and high labor intensity for workers. Now, after switching to constant pressure water supply using Senlan SB-90 frequency converters, 179,600 kWh of electricity can be saved annually, saving 109,500 yuan in electricity costs, extending the service life of the equipment and reducing the labor intensity of workers. (3) Application in air compressors In the past, air compressors generally used loading and unloading methods to supply air, which wasted a lot of electricity. Now, constant pressure air supply using Senlan SB-37 and SB-22 frequency converters can save 18,160,000 kWh of electricity annually, saving 110,800 yuan in electricity costs. The machinery factory has widely adopted frequency conversion speed regulation technology to modify the original equipment in machine tools and casting, which will not be introduced in detail in this article. It is worth noting that Although Roots blowers belong to the category of fans, they are not square torque loads but constant torque loads. Therefore, a high-performance frequency converter with torque control function should be selected for the speed regulation device. For drive motors under constant torque loads, if a standard motor is used, forced ventilation cooling at low speeds should be considered; otherwise, excessive motor temperature rise can easily lead to damage. 1.2 Green Lighting Project Lighting power consumption in China accounts for approximately 10% to 12% of the country's total power generation. In 2003, China's total power generation was 1.9 trillion kWh, and national lighting power consumption reached 190-228 billion kWh, about 2.5 times the 85 billion kWh generated by the Three Gorges Dam. After adopting green lighting, based on a 10% energy saving rate, annual energy savings could reach 19-22.8 billion kWh, equivalent to building an additional quarter of the Three Gorges Dam, which is of extraordinary significance. In 1996, 13 ministries and units, including the State Economic and Trade Commission, the State Planning Commission, the Ministry of Science and Technology, and the Ministry of Construction, jointly organized and implemented the "China Green Lighting Project," designating it as a major demonstration project in the field of energy conservation and environmental protection. To further promote the development of the China Green Lighting Project, in 2001, the State Economic and Trade Commission, together with the United Nations Development Programme (UNDP) and the Global Environment Facility (GEF), jointly implemented the "China Green Lighting Project Promotion Project." The aim was to gradually replace traditional inefficient lighting appliances with high-efficiency, long-life, safe, and stable-performance lighting products, thereby saving electricity for lighting, improving people's working, learning, and living conditions and quality of life, and establishing a high-quality, efficient, economical, comfortable, and safe lighting environment that fully reflects modern civilization. Through the implementation of the project, by 2010, it was expected to achieve a 10% reduction in lighting electricity consumption, i.e., saving 36.6 billion kWh of electricity that year, and reducing CO2 emissions by more than 1400 tons. The significance of green lighting lies in reducing electricity consumption and saving resources such as coal, thereby reducing the emission of greenhouse gases and other pollutants. The textile industry previously used inductive T12 type 38mm diameter 40W fluorescent lamps for lighting. The textile factory has now switched to electronic T8 type 26mm diameter 32W fluorescent lamps. The T8 type offers 12.28% higher illuminance than the T12 type, while saving 8W per lamp. The factory installed 6204 T8 fluorescent lamps, investing 292,000 yuan. Annual electricity savings amount to 357,000 kWh, resulting in annual electricity cost savings of 217,800 yuan, with a payback period of less than 1.5 years. The machinery factory previously had 450 450W fluorescent high-pressure mercury lamps with a total power of 202.5 kW. They have now switched to 450 135W Shenglu brand energy-saving lamps with a total power of 60.75 kW, investing 165,000 yuan. Annual electricity savings reached 430,500 kWh, resulting in annual electricity cost savings of 241,080 yuan. The entire investment was recovered in less than a year. my country's implementation of green lighting projects mainly involves the following four aspects: First, replacing T12 fluorescent lamps with T8/SUB type fluorescent lamps; second, replacing incandescent lamps with compact fluorescent lamps. Self-ballasted compact fluorescent lamps are electric light sources that integrate the ballast and the lamp tube, commonly known as "electronic energy-saving lamps." Under the same illuminance conditions, a 100W incandescent lamp can be replaced by a 25W compact fluorescent lamp, a 60W incandescent lamp by a 16W, and a 40W incandescent lamp by a 10W, achieving an energy saving rate of up to 75%; third, promoting the application of new electric light sources such as high-pressure sodium lamps, low-pressure sodium lamps, and metal halide lamps to gradually replace high-pressure mercury lamps; and fourth, promoting the use of energy-saving inductive ballasts and electronic ballasts. The lamps selected in the above two examples fully meet the requirements of my country's green lighting projects. From a building energy conservation perspective, lighting should make full use of natural light. Natural light is more suitable for human physiological needs and can improve work efficiency. Factory workshops should use glass doors and windows with high light transmittance, and the lighting area of ​​doors and windows should be maximized. In areas where natural light can be utilized, on-site illuminance can be measured according to standards, and automatic lighting adjustments can be made to supplement insufficient natural light. The current enclosed workshops in the textile industry are questionable. The author believes that traditional sawtooth-shaped workshops can better utilize natural light, and by selecting appropriate lighting control methods, better energy-saving effects can be achieved. 1.3 Energy-saving Retrofit of Electric Furnaces Electric heating equipment is the third largest consumer of electricity after electric drives and electric lighting. According to authoritative statistics, in 2000, the annual electricity consumption of industrial electric heating equipment in China accounted for 12.2% and 17% of the national social electricity consumption and industrial user electricity consumption, respectively. In 2000, there were 975,000 industrial heat treatment electric furnaces in China, accounting for 95% of industrial furnaces, consuming 8.6 billion kWh of electricity. Steelmaking electric arc furnaces consumed 13.2 billion kWh of electricity. Ferroalloy submerged arc furnaces consume 23.25 billion kWh of electricity, while calcium carbide submerged arc furnaces consume 11.5 billion kWh. my country's industrial resistance furnaces consume 500-670 kWh more per ton of workpiece compared to developed countries. Induction furnaces consume approximately 100 kWh more per ton. Steelmaking electric arc furnaces consume 270-370 kWh more per ton of steel, indicating significant potential for energy conservation. Therefore, energy-saving technological upgrades for various electric heating equipment are urgently needed. The machinery plant first upgraded four mud-core drying electric furnaces in its foundry branch. These four furnaces were all self-made resistance wire heating furnaces, each with a power of 55 kW, and the effective utilization rate of the furnace chamber was only about 65%, resulting in uneven heating. Later, an investment of 80,000 yuan was made to replace them with far-infrared radiation electric furnaces, increasing the furnace chamber volume, improving insulation, and significantly increasing thermal efficiency. Annual power consumption decreased from 792,500 kWh to 468,000 kWh, resulting in annual energy savings of 324,000 kWh and annual electricity cost savings of 194,400 yuan. The 80,000 yuan technical upgrade cost was recovered within six months. Overall, strengthening furnace insulation, improving the performance of heating elements, and enhancing heat radiation capacity are key to energy-saving upgrades. Heat storage and dissipation losses in the furnace body are the largest heat loss in resistance furnaces, accounting for 20% to 35% of the total input electrical energy, according to tests. If aluminum silicate fiber lining is used for the furnace insulation layer, the energy saving rate can reach about 50%, and the technical upgrade cost can generally be recovered in about one year. The heating performance of the heating elements directly affects the heating speed. For example, applying far-infrared coating to the inner wall of the furnace, using far-infrared heating elements, or embedding resistance wire in a spiral shape on silicon carbide tubes can generally achieve energy savings of over 20%. Black high-temperature energy-saving coatings can be sprayed onto the inner wall of the furnace to make it darker, which enhances the heat exchange process inside the furnace, increases the heating speed, and thus improves the thermal efficiency of the electric furnace. This generally results in a 5% energy saving. High-infrared heating is a new technology developed in the 1990s. It is a high-energy, high-density, high-intensity, full-band, instantaneous, and powerful infrared radiation heating technology, also known as high-infrared technology. Compared with traditional technologies, its curing efficiency can be increased by 2 to 40 times, the floor space can be reduced by 90%, the furnace length can be shortened by 90%, and the overall energy saving exceeds 50%, while the equipment cost is 75% of that of traditional curing furnaces. For example, the First Automobile Works in my country used high-infrared technology to upgrade the drying and curing furnaces of 13 painting lines, saving a total of 280 million yuan in technical and administrative fees and electricity costs. The Tangshan Locomotive and Rolling Stock Plant's powder coating production line achieved a 35% energy saving rate after upgrading with high-infrared technology. The Shanghai Xiechang Sewing Machine Factory's drying furnaces used high-infrared technology, achieving a thermal efficiency of 48% (compared to the usual 25%). 1.4 Use of High-Efficiency Electric Motors The textile factory invested 756,000 yuan to replace all its electric motors with high-efficiency energy-saving motors produced by ABB, with an efficiency of up to 94%. This resulted in annual electricity savings of 650,000 kWh and electricity cost savings of 392,000 yuan, recovering the investment within two years. Currently, the total capacity of various types of electric motors in operation in China is approximately 420 million kW, accounting for about 60% of the country's total electricity consumption. The widely used Y-series and Y[SUB]z[/SUB] series motors have average efficiencies of 87.3% and 86.3% respectively, basically meeting the energy efficiency limits in GB18613-2002 "Energy Efficiency Limits and Energy Saving Evaluation Values ​​for Small and Medium-Sized Three-Phase Asynchronous Motors". "Energy efficiency limits" refer to the efficiency values ​​that motor manufacturers must guarantee, and are mandatory indicators; "energy saving evaluation values" are the basis for product certification and are recommended indicators. Only motors that meet or exceed the energy saving evaluation value efficiency indicators can be called "high-efficiency electric motors". According to this evaluation standard, the textile factory's selection of the 94% efficiency high-efficiency motors provided by ABB is reasonable. With the continuous emergence of new materials and processes, the efficiency of the Y[SUB]z[/SUB]-E series 250M-4 high-efficiency motor (up to 94.2%) and the Y[SUB]xz[/SUB]-280s--4 type 75kW motor produced by Nanyang Explosion-proof Motor Factory has reached 94.5%, providing more choices for high-efficiency motors. A comparison table of energy-saving and other relevant data between the Y[SUB]z[/SUB]-E series and Y series motors is shown in the attached table. [ALIGN=CENTER] Attachment Table [/ALIGN] 2. Issues Worthy of Attention Harmonic pollution is causing increasingly serious damage to various industries in our county, especially to industrial enterprises, forcing some enterprises to implement special technical upgrades to address harmonic pollution. For example, the two enterprises introduced in this article have adopted technical upgrades to increase the cross-sectional area of ​​the three-phase power supply neutral wire to be equal to or greater than that of the phase wire. However, these upgrades only solve safety issues and are far from sufficient for controlling harmonic pollution. With the widespread use of high-power semiconductor devices in equipment such as frequency converters, soft starters, voltage regulators, electric arc furnaces, medium-frequency furnaces, industrial frequency furnaces, and welding machines, harmonic pollution of the power grid has become increasingly serious. Harmonics cause poor power quality, leading to increased additional losses in the power grid and terminal equipment, damage to equipment, and reduced service life. Harmonic pollution has been listed as the third largest source of pollution after air pollution and water and soil pollution, and various countries have formulated mandatory standards to limit harmonic pollution. The harmonic limit standard IEEE-1100, formulated by IEEE in 1992, stipulates that when the nonlinear loads such as motors, UPS, and frequency converters in the power distribution system are greater than 50%, the transformers should operate at less than 50% of their normal capacity. GB/T1454-1993 "Power Quality and Harmonics in Public Power Grids", approved and implemented by the State Bureau of Technical Supervision in 1993, clearly stipulates that the total harmonic distortion rate of the power grid at a nominal voltage of 380V should be less than 3%. Under normal circumstances, the power supplied by the power grid should be a 50Hz sinusoidal alternating current. When a sinusoidal voltage is applied to a nonlinear circuit, the waveform of the current flowing through the circuit will be distorted, becoming a non-sinusoidal wave. The voltage drop generated by the non-sinusoidal current across the grid impedance is superimposed on the sinusoidal voltage, causing voltage waveform distortion. For non-sinusoidal voltage and current, after Fourier series decomposition, the component with the same frequency as 50 Hz is called the fundamental frequency. Components with frequencies higher than the fundamental frequency are called harmonics, and the frequencies of harmonics are integer multiples of the fundamental frequency. The harmonics generated by nonlinear equipment in industrial enterprises are mainly odd harmonics such as the 3rd, 5th, etc. Power filters are the nemesis of harmonics. Power filters are divided into passive and active types. Passive filters target a specific harmonic by filtering it out through a combination of components such as reactance. Passive filters are most effective when the content of a certain harmonic in the power grid is high and the content of other harmonics is low. Active filters can filter out multiple harmonics, providing comprehensive power grid purification. ABB's PQF active power filter uses a real-time monitoring circuit to dynamically track constantly changing harmonic currents. It continuously converts these currents into digital signals, which are then processed by a signal processing circuit to generate a series of wideband pulse modulation signals. These signals drive the power module to output a current through the line reactor that is exactly opposite in direction and equal in magnitude to the harmonic current in the power grid. This cancels out the harmonic current, achieving the purpose of filtering harmonics and purifying the power grid. However, active power filters are expensive. Selection must be based on the nature of the equipment, purification requirements, equipment capacity, and investment capacity. Measurements and calculations must be performed, comparing the results with national standard harmonic voltage limits, to determine whether a filter should be installed, whether it should be passive or active, and what the capacity should be. There are generally three ways to install filters: 1) The filter is directly connected to the busbar of the distribution transformer, serving all loads downstream of the transformer. This method requires a large filter capacity. If multiple harmonics need to be filtered out, an active power filter should be selected. 2) For workshops with relatively concentrated nonlinear loads, such as areas with many frequency converters, centralized filter installation is preferable. This improves both the inherent harmonic interference and reduces pollution to the power grid. 3) One-to-one method. This method is highly targeted and effective, but requires a higher investment and is suitable for installing relatively dispersed and expensive equipment. The one-to-one method has good filtering effect, but when installing a large number of devices, it should be compared with the first two methods and considered comprehensively to achieve the best investment return. (Article sourced from "Energy Saving Innovation 2006 - Proceedings of the First National Electrical Energy Saving Competition")