Naturally-ventilated cooling towers, circulating water pumps, circulating water pipes and pipe fittings plant circulating water system is an important part of the preliminary design of the power system solution, determining the best system configuration, and reducing the positive construction costs.
The design of the circulating water system is the core part of the natural ventilation cooling tower. The reasonable selection and configuration of the circulating water pump has the largest investment and construction cost of the circulating water system. The most complicated construction has the greatest impact on the total investment of the power plant. It directly affects the unit cost of power engineering construction and equipment investment payback period.
The optimal design of the water supply system is in the selected scheme, and the system design based on the annual cost of the circulating pump motor is the most influential in the scheme design. Under the premise of how to reduce the annual cost of the motor, the safe operation of the steam turbine at full load is a worthy consideration for every engineer.
This article will address these issues. Reducing the annual cost of circulating water pumps and motor efficiency motors from the beginning of research, steam turbines to meet various operating conditions (including pure condensing conditions, maximum pumping conditions, rated exhaust conditions), reducing the premise of circulating pump motors Power equipment and improve motor efficiency.
In recent years, the national economic construction has reached a new climax. A large number of 135 MW high-pressure reheating units have been constructed throughout the country. Gansu Jinchuan Company, Shandong Huatai Thermal Power Plant, Power Plant, Shandong Liyan, Thermal Power Plant in Weiqiao, Binzhou, Shandong Province, Xuzhou Power Plant, the city of the power plant, we have designed 16 135 MW units, circulating pumps of 135 MW units in the selected water The system's long-term economic and safety management purpose in power plants promotes the use of energy-efficient circulating pumps.
1. Introduction of high energy circulation pump
1.1 Overview of the types of energy-saving circulating pumps:
Most of the domestic 100 MW, 125 MW, circulating water supply systems for 135 MW units, in most cases, the traditional arrangement has two sets of circulating water pump units, this configuration method to meet the "power plant technical regulations "Specifications", but also with the "hydraulic technology requirements" of the power system industry, are widely used in power plant design.
Economic analysis of the construction project of the power plant. The two pump circulating water systems used in the power plant are arranged in a regular mode every year, which has a high operating cost. The design also has some disadvantages mainly in the following aspects:
的设计点的价值体系正在运行，泵的效率不高。 The value system whose parameters deviate from the design point of the circulating is running, and the efficiency of the pump is not high.
The circulation survey of circulating pumps that have been put into operation has found that the operating efficiency of circulating pumps that exceed part of the time is the most popular. The pump power efficiency is not high, and the time invested is only about 60%. Pump efficiency. For most people, it is obviously not a pump efficiency. range.
Pump operating mode is not sensitive to changes in circulation system flow
For single-run school steam turbines, the cooling water of steam turbine condensers fluctuates with seasons and fluctuates every year; for variable turbines, extraction of steam with operating conditions increases significantly in cooling water systems. The thermal power plant uses a pump mode to run the most traditional machines in a year. One pump has insufficient water supply, two pumps have excessive water supply, and the difficulty in running and adjusting the pump is not conducive to forming the most favorable steam vacuum. With energy, in order to fundamentally solve the circulating water pumps, in different traffic problems, change the system configuration, improve the efficiency of the blood circulation pumps, produce high-efficiency energy-saving water pumps and develop inevitable. 1.2 Features of high energy-saving circulating pump
This article introduces the characteristics of the circulating pump from the article of circulating pump efficiency and energy saving. The new and new series of the design unit of the circulating pump of G and G48Sh 135 MW unit highlights the use of an example.
的新动力循环水系统设备和实际的吻，阻力参数，高效率泵的设计参数。 G48Sh circulating 's new power circulating water system equipment and actual kiss, resistance parameters, design parameters of high efficiency pump. Production and operation of more than 100 samples to test G48Sh circulating pumps, testing, G48Sh pumps operating efficiency of 84-88% above 135MW units arranged an effective conventional mode with two pumps 48Sh-22 model set of 25% actual efficiency equipment.
G48Sh new circulating water pump motor is equipped with bipolar, two-speed operation. The condenser cools the water every year according to different seasons. The motor adjusts and replaces the output speed of the motor, so that the water volume and the number of poles of the circulating pump change significantly. Increased system adjustment to maximize flexibility in saving plant electricity loads.
For example, in the case of electricity of G48Sh energy-efficient high-efficiency water pump pumps in summer, instead of two 48Sh-22 water pumps with a capacity of 3,000 tons / hour; in winter, G48Sh energy-saving water pumps run at low speed, and a number of water systems are equipped in the water system. The next 1080KW 680KW, 30% power reduction pump power reduction motor, equivalent to the power consumption of each pump, saving 2.3 million degrees per year.
G48Sh effectively promotes the optimization of the hydraulic conditions of the circulating pump of the energy-saving circulating water system, expanding the efficiency range of the pump. In two parts, it can ensure that the actual operating efficiency is not less than 85%. The circulating pumps with different speeds and the working efficiency of the pump are improved.
的配置。 The G48Sh energy circulating water pump was effectively introduced, which changed the design concept of the conventional configuration mode such as two circulating pumps (called the pump). The capacity turbine unit was proposed from a large capacity to a small configuration concept . Unlike high-speed large water pumps, low-speed, small water pumps are high-speed, low-speed, which integrates various pump operating conditions and utilize each other. Turbine changes in basic conditions to meet business needs. Energy-saving circulating pump horizontal pump housing, easy operation and maintenance.
1.3 Energy-saving configuration of circulating water pump
Gansu Jinchuan Company, Shandong Huatai Thermal Power Plant, Power Plant, Shandong Liyan, Thermal Power Plant Xuzhou Power Plant in Weiqiao, Binzhou, Shandong, the city of the power plant, we designed 18 sets of 135 MW domestic high-pressure units, reheating units. These plants have a common feature, in addition to the stable demand for electricity, basically their own enterprises, enterprises also have a certain amount of heat load, heat load fluctuations. Circulating water system enables significant changes in the water cycle of plants. In the case of heat load, the heating unit works basically under pure condensing operating conditions, which often occurs every summer. With the advent of winter, the heat load and heat load increase, the unit of heat load is greatly improved in extreme cases, production and life, the unit will exceed the operating extraction conditions. Most of these enterprises are located in the north, northeast, and northwest of China, and have longer heating time. Each year, the heating period is 4-6 months, and the individual life during the heating period is longer. The operation of the extraction unit for such a long period of time enables the circulating water of the power plant to have long-term low-flow conditions. Considering the requirements of the long-term power plant, the head of the economic operating range of circulating water pump flow and high-performance requirements is very long.
Take the 135 MW thermal power unit as an example: the conditions of VWO hydro turbines in summer, the capacity of steam turbine condensers is 32.17 tons / hour, 1 water, 19,640 tons / h cycle Unit; under the rated conditions of the extraction generator, the steam condensate control volume of the steam turbine is 223.36 tons / hour, 1 share of water circulation, 12274 tons / hour; under the maximum extraction conditions of the turbine, the turbine condenser condenses 142.6% Six ton / hour, water circulation, 4700 unit ton / hour on the circulating water system from 4700t / H to 19000T / H, and the water output of traditional pumps, such as according to the minimum unit arrangement to meet the flow of the cooling circulation pump When the flow is configured with the requirements of 9800T / H-11700T water heat load / h, the water is about 18.0-21.5 meters, and two water pumps run in parallel. Under the rated process conditions, a water pump is running. As the water resistance of the circulating water system is reduced, the pump's flow rate is 12274T / h, and the head will drop to 15.0-16.0 meters. In order to meet the circulating water system's highest extraction conditions, The requirement to run a water pump greatly reduced the supply of water, which drastically increased the pump head, a direct result of the gushing water from the cooling tower, a water spray device to increase the speed of the distribution channel, and poured water into the heat exchange to reduce the time of dripping. Reduced the cooling effect of the cooling tower. Of course, the heat-exchanging effect induced by the packaging will not get much attention in winter, but it will definitely pump out the high operating range of the pump, reducing the efficiency of the pump, and increasing the reactive power of the motor is a waste of energy in vain . The circulating pump motor has a power of 710KW, and a long-running power plant is not conducive to energy conservation.
In this case, a new pump configuration mode is required, which not only needs to meet the requirements of large flow and high head, but also meet the requirements of low flow and low head, large and small pumps, and high and low speed operation modes. This configuration mode emphasizes the large pump, high flow, according to the system's maximum flow, water flow and head high speed options to meet the system requirements. Small pump with large flow, as a large pump high-speed system flow 60% according to the selection, standby pump; according to the large pump low flow, low speed selection and small pump large flow, high-speed option A, small water pump, high-speed backup pump; in Low-speed small low-flow pump, in accordance with the system with minimum flow, the water supply system requires the head to be selected, in the absence of other backup pumps. Automatically adjust the pump size when the extraction conditions are changed by the unit, and the high and low speed operation of the pump can basically meet the requirements of circulating water in the water supply pump system.
2. Circulating pump for efficient use of energy
The unit of Shandong Shiliquan Power Plant's 125MW unit is equipped with 2 4 48SH-22 circulating water pumps running the same model set. In one year, the minimum flow rate of a single pump water supply system exists. Two auxiliary power pumps are added in parallel, which is too large, and the economical operation of the pump unit is inefficient. In October 1998, the # 4 pump (48SH-22) replaced the G48SH energy-saving water pump, and the high-efficiency energy-saving pump was put into production. The plant commissioned the Guangdong Electric Power Research Institute to perform energy-efficient water pump performance tests. The test results showed that: At low speeds, it is as high as 87.78% and 86.11%, which is 28.26% and 26.5% higher than the actual operation efficiency of the unmodified 48SH-22 pump, which significantly reduces power consumption, while the new water pump has flexibility in operation and adjustment.
Guangdong Yunfu, Phase II 125MW thermal power unit set up and water supply system, system configuration 4 48SH-22-the second type of the second circulation pump cycle, the water pump operation mode uses summer operation in the other three seasons, two sets of operation. Due to the low efficiency of each pump during operation, the flow rate is less than June 1998. It was discovered that it would replace the efficient G48SH pump circulation pump. High G48SH pump was put into operation. The Guangdong Power Science Research Institute Power Plant commissioned a new pump efficiency test. The test results show that the high-efficiency pump has a high operating efficiency of 87.78% when it travels at a high speed of 16,357 tons / h. Flow, motor power 1002KW, low speed of 13,800 tons flow / h, actual operating efficiency of 86.12%, motor power 646KW, pump unit operation and consistent operating conditions. 的工作条件，不符合条件的单位经营流量。 The original actual working point pump water flow rate is 144,000 tons / hour, the efficiency is 59.62%, the motor power is 1089KW, and the maximum efficiency is 70%. 15.4 million tons / h, the working conditions of the are not qualified units Operating flow. This shows that the new large pump is 2137 tons of water pump / hour, high efficiency, low power motor 87.7KW, and the new low speed pump single pump saves 443KW per hour.
In December 1998, the secretary of the Ministry of Electric Power Industry organized the appraisal, and the scientific and technological achievements issued by the appraisal certificate were popularized nationwide.
Three, concluding remarks
Of course, the promotion of any new technology requires an understanding of the process. The characteristics of high efficiency and energy saving are the energy saving and high efficiency of the largest circulating pump. But whether it is applicable to all regions, the operation status of all 135 MW units proves that more practical applications are needed, but more choices must be tailored to local conditions. The promotion of energy-saving circulating pumps is not only related to the configuration of circulating pumps in power plants, the operating costs of water pumps and standby pumps, but also the interlocking control of the operation of water pumps and generators, especially in the Yangtze River. The energy is much larger than the capacity of the pump than other geometric dimensions. In terms of river pumping stations, equipment and equipment operating costs, less than the structural cost and construction cost of the pumping station, especially the high efficiency, the maximum water level is increasing between low water level Difference in time level.