Energy Saving Application of Lingke Inverter in Oil Storage Pump
Foreword:
In the production and operation process of the oil depot, the oil pump is the equipment with the highest average daily frequency in the entire production system, and the start method of the oil pump in most oil tanks uses the star-delta start-up, due to the impact of the star delta startup method on the motor and the oil pump. Intensified, resulting in accelerated wear of oil pump bearings and increased noise and many other weaknesses. The following are the field data obtained when the company reconstructs the oil in the Sinochem’s Qinhuangdao Storage and Transportation Center’s Huayang Oil Depot.
Keywords: Frequency converter Fuel pump Energy saving
I. Operation status of the 37KW oil pump of Huayu Oil Storage
The oil tanker of Huayang Oil Storage is composed of 4 sets of 37KW vertical oil pumps, and is mainly responsible for 8 oil loading points in 4 work platforms for metering and loading oil trucks. The output flow of the pipeline design at each loading point is 60 cubic meters per hour, the flow rate of the 37KW oil pump is 180 cubic meters per hour, and one oil pump assumes the task of oiling for two loading points of a workbench (respectively No. 1 valve and No. 2 valve, the valve opens and fills oil to the oil tanker; while in the actual production and operation, only one oil valve is opened for most of the time, and the two oil loading vehicles are loaded with little oil at the same time. When the original designed 37KW oil pump was two The platform truck is designed for operation at the same time. However, when a valve is opened, it must be operated at full capacity. The output flow of the pump can reach 180 cubic meters per hour at full load, and only one-third of its flow rate will be required for actual use. Satisfy the production requirements, through the analysis of the working principle of the entire oil delivery system, the existing oil pump operating principle has the following problems:
1, 37KW pump output flow is too large, in the opening of an oil valve only need one-third of the flow of the pump, the pump is fully loaded each time the load 180 cubic output operation, so that the pump and the pipeline have a lot of pressure The difference is that vortex pressure is formed. When the differential pressure in the pipeline increases, the load on the motor increases, the current increases, and power is wasted.
2. Due to the large output volume of the oil pump and the actual pipeline transportation volume, this operating environment generates a lot of useless power consumption in the operation of the oil pump, which greatly shortens the service life of the oil pump motor and increases the equipment maintenance cost.
To sum up the background of the above work, it is necessary to upgrade the energy-saving operation of the pump motor system, use the frequency converter governor to operate the oil pump, in order to obtain adjustable flow and pressure, and automatically control the oil pump system according to the actual demand of the flow and pressure. .
Second, the fuel pump system uses the principle of energy-saving technology of variable frequency speed running The oil pump in the original operating characteristics of the motor start to run at 50Hz, speed 1420r/min turn, the output flow of 180 cubic meters, speed and flow pressure is proportional, as shown :
Fig. 1: Operating principle of the oil pump
As we can see from the above figure, the flow rate of the oil pump motor decreases with the decrease of the rotation speed of the oil pump motor. Therefore, only using the frequency converter can make the rotation speed of the oil pump motor become freely adjustable, and at the same time, the flow and pressure of the oil pump can also be made. Tuning, through the adjustment of the frequency conversion to achieve the existing production process requirements. We use the special frequency converter LK600P series oil pump produced by Beijing Zhongda Lingke Electric Co., Ltd. to improve the working characteristics of the oil pump, and make full use of the speed control function of the frequency converter to achieve adjustable flow and pressure, to adjust the motor arbitrarily Speed ​​to achieve the purpose, but also to save energy, long oil pump motor service life, environmental protection and energy saving is the original intention of this project.
The energy saving principle of the oil pump through variable frequency operation?---The working principle of the frequency conversion is not described in detail here. We can see from the comparison chart below that the motor speed changes during the frequency conversion operation and the motor load current also changes. Of course, the output voltage of the inverter will also decrease as the motor speed decreases, and the load current of the pump will also decrease as the voltage drops. The data described below is the actual data measured by the company's on-site motor operation. Fig. 2: The table shows the motor load current when the 37KW oil feed frequency is running. Table 1: The change of the oil pump motor speed, motor running current and the flow rate at any speed when the 37KW oil pump is running in variable frequency.
Fig. 2: Motor load current during 37KW power frequency operation
Table 1: Variations of load current and flow rate at different speeds for a 37 kW pump in variable frequency operation.
Pump motor model
Power frequency running current
(A)
Frequency conversion running motor speed into
(Hz. r/min)
Actual load current of oil pump
(A)
Pump output flow
(cube)
Y225M-4
37KW
74A
50Hz-1420r/min
74A
173
45Hz-1278r/min
61A
158
40Hz-1136r/min
51A
123
37Hz-1050r/min
49.5A
117
35Hz-994r/min
48A
110
33Hz-937r/min
47.5A
107
30Hz-852r/min
45A
90
25Hz-710r/min
43A
71
20Hz-568r/min
43A
40
On-site data: A 37K oil pump of Huayu Oil Depot supplies two injection valves on a workbench. The output flow rate of one oil injection valve is 60,,,, and cubic. When two open at the same time, the flow rate can reach 120 cubic meters to meet production requirements. To achieve a fuel injection valve open, the inverter only need to output an accurate flow of 60 cubic meters? It is explained in detail in the following Solutions. When carrying out oiling work for a tanker, the inverter runs at 25Hz and the motor current is 43A, which can save a current of 51A and a saving rate below 60%. When the two fuel injection valves are opened to fuel the two oil tankers, the frequency converter operates at 35 Hz, the motor current is 48 A, the current is saved at 26 A, and the energy saving rate is below 40%.
From the above list and field data, the operation principle of the existing oil pump in China Coal Qinhuangdao Storage and Transportation Center has been divided. I can see the role played by the frequency converter in running the oil pump and control the motor speed of the oil pump through frequency conversion. The oil pump output a reasonable flow and pressure to meet the production requirements, but also greatly reduce the load current of the bottom motor, energy saving is very obvious.
Third, the inverter control method
The function of the frequency converter is to provide a variable frequency power supply for the motor and achieve stepless speed regulation of the motor, so that the oil pressure of the pipe network continuously changes. The task of the pressure transmitter is to inspect the flow and pressure of the pipe network. The setting unit of the flow and pressure provides the system with the expected value of the flow and pressure that meets the user's demand. The flow and pressure setting signal is input to the inverter through the 4-20mA current feedback signal and then calculated by the inverter's internal PID control program. It outputs a speed control signal to the inverter, and the inverter starts to work when it receives the 4-20mA current signal. First, start the pump motor, so that the hydraulic pressure of the pipe network flow reaches the set value. After the output frequency of the inverter reaches the apex with the flow rate and pressure, the speed of the inverter starts to decrease until the pressure and flow of the pipe network are maintained in line with the production. Required within the required predetermined value. When the oil quantity increases or the pressure of the pipe network weakens when the two oil outlet valves are opened, the pressure transmitter processes this signal into a 4-20mA signal and sends it to the inverter. (Note: The inverter is based on the 4-20mA current value. To determine the size of the output frequency, the frequency is the motor's speed is high and low), the frequency of the inverter starts to rise, so that the output frequency of the inverter increases, the speed of the oil pump increases, the flow and pressure increase accordingly, if the output flow of the oil injection increases, The output frequency of the inverter will reach the maximum value of 50Hz. Based on the above, the built-in PID control through frequency conversion can make the entire oil supply system more operable and greatly reduce the labor density.
Since the electrical system of the entire Huaku Oil Depot adopts the upper machine set control, the pump motor is started by soft start, the start and stop of the pump, centralized control and machine side control, respectively, and the operation platform is two åMiss electromagnetic valves. Solenoid valve switch to bear the fuel to the tanker, åMiss electromagnetic valve with flow metering and pressure transmission function, can provide a 4-20MA transmission signal output for the inverter, the pressure transmission value can be freely set size The set transmission value corresponds to 4-20MA output. When the 4-20mA signal input interface of Lingke Inverter receives the current signal transmitted by the pressure transmitter, then according to the size of the signal source and then through the built-in PID control of the inverter, it can automatically and completely make the oil pump at the predetermined flow pressure. Work within, to achieve the production process requirements of the production line.
Fourth, the system program In the operation of the oil depot production process, the oil pump in the entire system is a very important production equipment, requires the inverter can be continuous operation for a long time, should have the performance of the outside, but also have a very high reliability, in understanding the site The characteristics of the production process combined with the design of the design, the system design should have the ability to adapt to the site operation, and fully compatible with the original electrical system, so that the original control characteristics remain unchanged; the system design has the following functions:
1. The power frequency soft starter system of the frequency conversion system and the prime mover cabinet can be manually switched freely. Once the frequency conversion system has a certain failure, it can be manually switched to the power frequency soft start of the prime mover cabinet. During the frequency conversion system maintenance, the original soft starter system can normally guarantee the operation of the oil pump and meet the normal production of the oil tank.
2. The frequency of the frequency conversion system is adjusted by PID closed-loop control loop. The output frequency of the inverter is determined according to the flow pressure transmission 4-20mA letter. This ensures the safe operation of the oil delivery system and makes the whole system more convenient for operation. Intelligent automation is stronger.
Figure 3: Inverter pump wiring diagram
3. Considering the working environment of the site and the safety of the equipment, the frequency conversion control cabinet panel should not set too many display devices, only configure the soft starter and frequency conversion switch, operation indicator, frequency conversion operation fault lamp, frequency conversion operation display panel, The operating parameters, motor current and motor speed of the inverter are clear at a glance, which greatly facilitates the operation of the on-site operator and the monitoring of the operating status of the equipment.
4. 6-digit password is set in the frequency conversion system, which can lock and protect the operating parameters of the inverter to ensure that the frequency conversion oil delivery system will not cause the shutdown of the oil pump under human-induced faulty operation, thus achieving continuous and stable operation of the system.
5. The inverter adopts independent wiring power supply to prevent electromagnetic interference to the equipment and ensure the safe operation of the equipment.
6. The frequency conversion system implements soft start and soft stop for the oil pump motor, which reduces the impact on the power grid during the start-up process, improves the power supply quality and also extends the maintenance cycle of the oil pump motor. As the use of frequency conversion, the motor speed is reduced compared to the original. The low-speed operation will reduce the wear of the oil pump shaft and bearing, which will greatly extend the life of the oil pump bearings, mechanical seals and other consumables.
V. Project cost
This project is composed of 4 sets of 37KW fuel delivery pumps. The frequency converter selects 4 sets of 37KW LK600P series oil pump-specific frequency converters. The total project cost is as follows:
No.
Product number
Quantity
Unit price RMB
Total amount of RMB
Total project cost RMB
1
Lingke LK600P-037T4
37KW frequency changer
4
17800.00
71200.00
129900.00
2
Frequency converter cabinet GPT
4
4300.00
17200.00
3
Air switch, contactor, display panel,
Switch, indicator, smart feedback card
4
5300.00
21200.00
4
Control line and main motor cable
1
12000.00
12000.00
5
Field wiring construction fee
1
8300.00
8300.00
Six, investment cost recovery period
The 4 pumps are calculated on a daily basis for 12 hours. According to the measured average energy saving rate of 40% (this data is the actual value of other projects, does not represent the accurate data of this project), all investments can be recovered in 4 months.
7. Concluding remarks Throughout the production and operation of the oil depot, the oil pump is the main production link of the entire system, and is also a major power consumer in the entire operation system. It is necessary to save energy and reduce consumption of the oil pump. Currently, the energy-saving pump is used to save energy. The effective technical way to reduce consumption is to use frequency converters and to use frequency control to improve the working efficiency of the fuel pump. During the entire system implementation and operation, the inverter not only performs an intelligent upgrade on the entire system, but also makes the entire production operation process more humanized and intelligently automated. At the same time, it also brings huge economic benefits, such as the long service life of the oil pump. Reduced maintenance costs, etc. It is believed that the beneficiaries of this project are more experienced than the project implementers.
Author: Zhang Xiaolian
Position: Electrical Engineer
Now at: Beijing Zhongda Lingke Electric Technology Co., Ltd.
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