Hard Parts For Automobile Maintenance CHANGGE FUKANG MACHINERY ACCESSORIES CO. ,LTD , https://www.fukangcasting.com
Keywords: feed pump, front pump hydraulic coupling, variable frequency speed control system, energy saving.
First, on-site situation before the frequency conversion transformation Baotou Donghua Thermal Power Co., Ltd. is located in Baotou City, Inner Mongolia, installed 2*300MW turbo-generator units, each unit is equipped with three sets of 50% of the rated capacity through the hydraulic coupler driven electric feed pump, The feed pump group is equipped with a fore pump that is driven by the feed pump motor at the same speed as the constant speed drive.
According to the statistical data of Baotou Donghua Thermal Power Co., Ltd., the No. 1 and No. 2 unit feed pumps are designed as 3x50% rated capacity electric feed pumps, which are equipped with hydraulic couplings for speed control. In 2010, the power consumption of the feed pump of No. 1 unit accounted for 2% of the power generation, and accounted for 23% of the power consumption rate of the power plant. The power consumption of the unit was very large. Directly affect energy consumption and power generation costs. Therefore, it is very necessary to optimize and reform the speed control mode of the electric water pump.
This time it is planned to transform the frequency conversion and energy saving comprehensive upgrading of the #1 feed pump of Unit #1, that is, the technical transformation of the pre-pump, the technical transformation of the hydraulic coupling, and the transformation of the high-voltage frequency converter.
In order to further adapt to the power system with separate plants and networks, and to compete for electricity, save energy, reduce plant electricity rates, protect the environment, simplify operation methods, and reduce wear and tear on rotating equipment, the company decided to use Beijing Leader Huafu on generator set feed pumps. Electric Technology Co., Ltd. production of high-voltage inverter speed device.
Second, the feed pump system conditions to the pump unit equipment technical parameters:
Table 1 Pre-pump parameters
Third, the frequency conversion transformation program introduction This transformation mainly involves the following aspects: The system main loop control plan, the front pump, the fluid coupling and the oil system transformation plan. We will introduce the relevant sections as follows: 
Figure 1: On-site high-voltage inverter 
Figure II: Air cooling system 
Figure 4: Equipment connection diagram
In response to the above problems, Lead Huafu Company has given serious solutions to the following solutions:
Table 5 The actual operation data corresponding to each load of the water pump group
The pump characteristic is shown below: 
Figure 5: Pump characteristics
Under 50MW load, the feed pump speed is about 3000rpm, the front pump head is about 30m, and the required cavitation allowance for the feedwater pump is about 8m, so there is enough safety margin.
Under 100MW load, the feed pump speed is about 3800rpm, the front pump head is about 50m, and the required cavitation allowance for the feedwater pump is about 15m, so there is enough safety margin.
That is, the front-stage pump still remains to be driven by the original motor and operates at a variable speed along with the motor. It is recommended to set the minimum speed of the feed pump to 3000 rpm during variable frequency operation.
3.2.2 Liquid Coupling and Oil System Modification Program The on-site fluid coupling is mainly composed of two parts. One is the speed increasing gear. The role of this part is to increase the rated speed of the motor to the rated operating condition of the feed pump. Speed; First, the pump wheel, turbine, scoop tube, and circulating oil system, its role is to adjust the circulating oil through the spoon tube, change the amount of oil in the coupling, so as to adjust the turbine speed, to achieve non-polar speed output speed.
According to the actual conditions on site, the specific renovation plan is as follows:
(1) When the fluid coupling is not removed, the liquid coupling position is opened to the maximum during variable frequency operation, and the fluid coupling acts as a coupling.
(2) Since the main oil pump is coaxial with the motor, after the frequency conversion is adopted, the motor oil pressure and oil quantity will be insufficient after the motor speed is reduced. The oil pump requires a lubricating oil pressure of not less than 0.25 MPa, and the lubricating oil quantity shall not be less than 360 L/min. The working oil pressure is not less than 0.25 MPa, so to meet the fuel supply of the oil pump, configure the oil station separately. The main fluid coupling main pump is removed, including the modification of the oil pipeline at the oil station, the basic production and installation of the oil station, and the removal and modification of the main oil pump impeller of the fluid coupling.
(3) Configuration of the oil station: three oil pumps (including the drive motor), dual-use and one-time preparation, operation pump fault trip, and chain standby pump start. The flow rate is 1200 liters/minute, pressure: 0.40 megapascals, power: 4 levels 22 kilowatts, calibre: 80. The oil station is equipped with three electrical control boxes that meet the pump motor capacity and control requirements. It is used to implement the fuel tank, oil temperature, oil pressure, and oil level detection. The detection signal can output 4-20mA signals.
(4) When the inverter is faulty or overhauled, it is switched to the power frequency operation by the inverter bypass. At this point, it still follows the original mode of operation, using liquid-coupled speed control. 
Figure 6: Renovation of on-site petrol station oil supply system 
Figure 7: Field Fuel Supply Control Box
Fourth, before and after the transformation of the frequency conversion device data comparison and efficiency analysis When using frequency control, you can need to increase or decrease the motor speed, change the performance curve of the pump, so that the rated parameters of the pump to meet the process requirements. 
The following energy saving report is the running energy saving report issued by the user:
In 2012, when the pumping frequency was put into operation, the frequency conversion of the feed pump was 792.324 million kwh per year, which could reduce the electricity consumption rate of the power plant by 0.53% and the electricity consumption rate of the integrated plant by 0.26%. Throughout the year, it can generate revenue of 792.3345×0.3109=2.4634 million yuan. According to the annual power consumption of the water pump of 29,532,800 kilowatt-hours, the energy-saving effect will reach 26.8%.
V. Concluding remarks After the high-voltage frequency conversion device was put into operation, it worked well and the energy-saving effect was obvious. After adopting variable-frequency speed regulation, the soft start of the motor was realized, the impact on the power grid at startup was reduced, the life of the motor was prolonged, and the pipeline was also reduced. Vibration and wear; In short, the application of the HARSVERT-VA high-voltage frequency converter in frequency conversion speed regulation of Baotou Donghua Thermal Power Unit feed-water pump system is quite successful.
Application of Leader Huafu HARSVERT High Voltage Frequency Converter in Baotou Donghua Thermal Power Feed Water Pump
Application of Leader Huarong HARSVERT high-voltage frequency converter in Baotou Donghua Thermal Power Feed Water Pump Beijing Lide Huafu Electric Technology Co., Ltd. Abstract: Through the frequency control of the unit's electric feed pump and the modification of its auxiliary equipment, the operation is improved. Technology, saving electricity. 3.1 The basic principle of the system's main loop control scheme: It consists of three high-voltage vacuum circuit breakers QF1, QF2 and QF3 (see the figure below). It is required that QF1 and QF2 cannot be closed at the same time as QF3 and that they are electrically interlocked. During frequency conversion operation, QF1 and QF2 are closed and QF3 is opened. When the power frequency is running, QF3 is closed and QF1 and QF2 are disconnected. The front pump and the motor are connected coaxially, so after the conversion of the frequency conversion, as the motor speed changes, the speed of the front pump will also change accordingly, which will cause the pressure and flow rate of the front pump outlet to change. Due to pressure and flow rate changes, cavitation occurs in the feed pump. After preliminary calculation, the parameters are as follows:
model
SQ250-560
Yang Cheng
103m
Shaft power
110KW
flow
553.6 m3/h
Rated speed
1490rpm
Inlet pressure
0.65MPa
Necessary NPSH
Inlet temperature
165°C
Water pressure
1.1MPa
Manufacturer
Table II Feedwater Pump Motor Parameters
model
YKS5400-4
Rated speed
1491rpm
rated power
5400KW
Power factor
0.85
Rated voltage
6KV
cooling method
Water-air
Rated current
599A
No-load current
Table 3 Fluid Coupling Parameters
Model number
GCH104A-47
Speed ​​range
20% to 97%
Rated input speed
1490rpm
Rated slip
2.4
Rated output speed
1310-5239rpm
Rated output power
5400KW
Manufacturer
Table IV Pump parameters
model
CHTC5
Yang Cheng
2067m
flow
563.8m3/h
Inlet temperature
165°C
Shaft power
5400KW
Inlet pressure
1.1MPa
Rated speed
5239rpm
Outlet pressure
19.896MPa
Manufacturer
Shanghai Kaishibi Pump Co., Ltd.
Figure 3: Frequency conversion control diagram of the main loop
3.2 Renovation of related equipment 3.2.1 Pre-pumping solution Unit load (MW)
Flow (m3/h)
Feed pump current (A)
Feedwater pump inlet pressure
(Front pump outlet) (MPa)
Feedwater pump outlet pressure
(MPa)
50
256.45
208.96
1.5
7.54
100
317
277.7
1.4
12.1
150
435
339
1.4
13
200
520
436
1.65
14.65
250
554
527
1.8
16.21
Figure 8: Water pump frequency conversion performance curve
If the speed is reduced by half, that is: n2/n1 = 1/2, P2/P1 = 1/8, it can be seen that reducing the speed can greatly reduce the shaft power to save energy. As can be seen from the figure above: When the speed is reduced from n1 to n2, the rated operating parameters of the pump Q, H, P are reduced. However, from the efficiency curve η-Q, the efficiency value of the Q2 point is basically the same as the efficiency value of the Q1 point. In other words, when the speed is reduced, the rated operating parameters will be reduced accordingly, but the efficiency will not be reduced and sometimes even increased. Therefore, under the premise of meeting operational requirements, the pump can still work with the same or even higher efficiency.