Application of High Efficiency and Energy Saving Circulating Water Pump in Water Supply System


In power engineering construction, the water supply system has high investment and large construction volume and complex construction. It has a great influence on the construction cost of power engineering and the investment recovery period. In the design of power plant water supply system, attaches great importance to the selection of natural ventilation cooling tower and circulating water pump, Circulating water pipe system optimization layout, because they directly affect the safe operation of turbines and generator full load power generation, a direct impact on power plant economy, in order to reduce annual operating costs of water supply system, save the project cost must promote the application of energy-saving equipment, optimize the system Configuration.

The cooling water quantity of the turbine generator condenser in the thermal power plant varies with the seasons, and the cooling water volume in summer is large and the cooling water flow in winter is small. With the steam turbine extraction volume variation, the cooling capacity of the steam extraction turbine with large cooling capacity is small and the cooling capacity is small. The water supply system uses one unit with two sets of parallel pumps of the same type and distributes the circulating cooling water equally to two circulating pumps. This configuration mode is in accordance with "Rules and Regulations of Hydro-power Plant Hydraulic Technology" and is used in the design of power plant water supply system widely used. However, a unit with two sets of the same type of pump often run into problems during the operation, in order to fundamentally solve the problem of low pump efficiency and system flow inconsistencies in the pace of development, the development of a new energy-efficient pump is inevitable.

Application of High Efficiency and Energy Saving Circulating Water Pump in Water Supply System

In recent years, a large number of 135MW thermal power plants have been built in various parts of the country. In Shandong Riyan Power Plant, Xuzhou Power City Power Plant, Gansu Jinchuan Power Plant and Shandong Weidiao Thermal Power Plant, we have designed 18 135MW domestic EHV and intermediate reheat units successively. These power plants are located in North China, Northeast China and Northwest China. The common feature is that enterprises use their own resources for their own use. In addition to the stable power demand, there are heating loads, large heating load fluctuations, small summer heat load and large winter heat load. long.

Taking 135MW heating unit as an example, the condensing capacity of the steam turbine condenser is 324t / h when the steam turbine is continuously discharged, and the circulating cooling water volume is 19640m3 / h. The steam condensing capacity of the steam turbine when the steam turbine is in the rated extraction condition is 223t / h, the need for circulating cooling water 12274m3 / h; Turbine maximum extraction steam turbine condenser condensate 143t / h, circulating cooling water 4700m3 / h. Changes in the operating conditions of the random group, the huge fluctuations in the amount of cooling water required for circulating water system from 4700m3 / h - 19000m3 / h.

In order to meet the requirements of steam turbine operation in summer, the water flow rate is 9800-11700m3 / h and the lift is 18.0-21.5m. According to the parallel operation of two water pumps in summer to meet the needs of circulating water system, the cooling water volume is 19000m3 / h In other seasons, a pump runs to meet the needs of circulating water system cooling water. The flow range of the water pump is 9800-11700m3 / h. When the system exceeds this flow range, the pump is not economical to operate.

Not difficult to find: Turbine rated extraction conditions, the cooling water demand for the system is 12274t / h, the system water resistance than pure steam turbine condensing conditions slightly reduced 2.0-3.0 meters, the pump head dropped to 15.0-16.5 meters, single Taiwan water pump flow increased to 13000t / h, a pump running to meet the system requirements, but not running high efficiency. However, the maximum steam turbine steam extraction conditions, the circulating cooling water volume is only 4700t / h, the system water resistance than pure steam turbine condensing conditions significantly reduced, resulting in increased pump lift, low operating efficiency, resulting in cooling tower water pouring device, plus Large sink flow rate, water heat exchange time reduced. Due to the extremely low efficiency of the pump, motor reactive power increases, wasted power.

If the 135MW domestic EHV, intermediate reheater circulating water system using new energy-efficient pumps, water pumps will fundamentally solve the problem of low efficiency and inconsistent flow of system changes in the contradictions.

Take G48Sh pump as an example, when the speed is n = 485r / min, the pump flow rate is 17500m3 / h, the lift is 18m, the pump efficiency is 88% and the shaft power is 947kw. At the speed of n = 420r / min, the pump flow is 13200m3 / h, 14.5 meters, pump efficiency 87% shaft power 587kw. The pump design parameters and 135MW unit circulating water system parameters basically consistent, high operating efficiency. More than 100 G48Sh pumps for sampling, the actual operating efficiency of 84-88%; conventional 48Sh-22 pump operating efficiency of only 60%.

Pump equipped with a motor with bipolar number, double-speed core technology, an increase of circulating water system operating flexibility. According to the condenser cooling water volume changes with the seasons, with the steam extraction volume changes automatically adjust the motor pole number and speed, while changing the output power and pump water supply. A G48Sh pump running at high speed than two 48Sh-22 parallel pumps more than 3000 tons of water per hour; a G48Sh pump running low-speed motor output power can be adjusted from 947KW to 587KW, the motor power decline of 37%, and its energy-saving effect very obvious. Because the circulating water system in addition to the summer high-speed pump operation, the other seasons basically can run at low speed, according to the annual running time of 7200 hours, each pump can save 2.3 million degrees per year. According to the power plant price 0.2 yuan / kWh, a single circulating pump annual electricity savings of about 400,000 yuan, according to 10-15 years of recovery life, a single circulating pump to save electricity up to 400-600 million for the installation of a few Taiwan's energy-saving circulating pump power plant, its considerable economic benefits can not be underestimated, which is a power plant many energy-saving technological transformation of a direction of development. The conventional pump equipped with a fixed motor is not adjustable, a certain speed corresponding to the output power is constant. A single energy-efficient circulating pump than the conventional capacity SH series centrifugal pump prices high 15-20 million, this part of the investment cost only low-speed operation of the motor can recover the full cost of a very short period of time.

The introduction of high efficiency and energy saving circulating pump can optimize the system hydraulic conditions, widen the range of high efficiency pump to effectively improve the efficiency of the pump; changed a steam turbine with two conventional capacity of the pump design concept, proposed a new The pump configuration to meet the steam turbine working conditions of variable conditions, the body structure of the horizontal pump shell design, plant operation, maintenance is very convenient.

Shandong Shiliquan Power Plant (2 × 125MW) circulating water system originally equipped with 4 sets of the same model 48SH-22 pump operation, there is indeed insufficient water pump, low efficiency, poor economic performance. In October 1998, 4 # pumps were replaced with G48SH pumps. After commissioning, the power plant commissioned the Electric Power Experimental Institute to test the performance of the pumps. The operating efficiencies were as high as 87.78% and 86.11% at high speed and low speed, respectively, Efficiency increased by 28.26% and 26.5% respectively, with a significant reduction in power consumption.

Guangdong Yunfu Power Plant (2 × 125MW) is also equipped with 4 sets of the same type of circulating pump 48SH-22. 3 pumps in summer run, 2 runs in other seasons. Because of the lack of circulating water flow, the efficiency is low, it will be changed to G48SH pump commissioned by the Guangdong Electric Power Research Institute on the pump efficiency testing, the new pump high speed actual flow 16537t / h, operating efficiency 87.78%, motor power 1002KW; When the new pump low speed actual flow 13080t / h, operating efficiency of 86.12%, motor power 646KW. Pump and unit operating conditions match. The actual flow of the original pump 14400t / h, efficiency 59.62%, motor power 1089KW; the maximum efficiency of 70% when the flow of 11540t / h, pump and unit operating conditions do not match. The new pump is 2137 t / h higher than the old pump with high speed, the power is 87.7KW and the efficiency is 28.16%. The new pump can save 443KW per hour when the water supply is the same at low speed.

in conclusion

The promotion of any new technology requires a cognitive process, the most important feature of energy-efficient water pump is energy saving, high efficiency, it is worth to promote in the country. However, whether it is suitable for all regions or not, all 135MW units need more practical application proofs and need to be tailored to local conditions.

Promote energy-efficient circulating pump not only involves the configuration of the circulating pump in the power plant, pump standby and pump operating costs, but also related to the pump and steam turbine operation of the interlock, control problems, etc., especially in the construction of the Yangtze River water pumping station must be carefully selected , The energy-saving circulating pump geometry is much larger than the capacity of the pump, the waterfront pump room, equipment and equipment operating costs less than the structure and cost of water pumping station construction costs, especially the water source water level and the highest water level difference Larger, any changes in the geometry of the water pumping station on the project cost is very large.

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