High Voltage High Power Inverter In The Desulfurization Process In The Applicati
1 Introduction Subsidiary PetroChina Southwest Oil Purification Plant located in Western North Gas Field in Sichuan Jiangyou City, Sichuan Jiangyou in the field Leikoupo dam reservoir of natural gas as raw material for purification of natural gas processing, daily processing capacity of 500 000 m3, is the key enterprises in Sichuan Province. The main products are: sulfur, oil LPG , Natural gas, production of chemical products sold at home and abroad. Northwest Gas Field purification plants typical of the petrochemical industry, equipment varieties, high value, good rates on equipment and continuous operation, high availability requirements. Northwest Sichuan Gas Field
purification plant desulfurization branch 1 #, 2 # two Cycle Pump during normal operation “of a one stand,” two Motor Are direct-frequency start, start the current, not only affects the equipment life expectancy have a greater impact on the network. Desulfurization process, day and night cycle of water temperature higher, on the circulation of water to make the necessary adjustments. But the original device frequency constant speed running, only by adjusting Valve The opening to adjust the size of circulating water through man-made changes in pipe resistance, increased wear and tear pipeline to transfer Water Volume, resulting in a large part of the energy wasted in the valve, resulting in high tariffs. Use valves regulate the flow, not only can not run the economy, and increased the workload of workers, regulation is not timely, but also result in high or low pressure pipe, flow excessive or too small, affecting the safety of the production process and equipment run. To reduce the economic cost of desulfurization of production, improve the process accuracy and efficiency, the urgent need for 1 #, 2 # circulating water pump speed Saving Energy.
After repeated investigation, inspection, comprehensive comparison of the speed control devices currently on the market and eventually decided to use Beijing Lead China peking production HARSVERT-A direct high – high frequency converter to the two circulating water pump Energy Saving.
2 working characteristics 2.1 Process Northwest Natural Gas Purification Plant Desulfurization circulating water system consists of the following five components: cooling towers, the middle pool, circulating pump, overflow pumps, desulfurization unit. Discharged from the desulfurization equipment cycle hot water, cooled by the cooling tower into the middle pool of storage; which most of the water by circulating water pump for re-use of desulfurization equipment, spare parts from the overflow Pipeline Overflow. Process flow diagram shown in Figure 1.
2.2 Process requirements (1) constant temperature and out of the cooling tower
Required constant temperature range (4 < t <8 ); such as the circulating pump valve to open a large volume of water increases, the cooling water temperature decreases, volume decreases, the temperature increases.
(2) a minimum pressure clamp control
Desulfurization equipment required to ensure entrance Converter in pressure (greater than 0.45Mpa) under the premise of recycled water saving water as much as possible to find the desulfurization process to meet production requirements, the minimum threshold pressure.
2.3 site status Inverter room long 7200mm, width 3000mm.
2.4 Field Instrument Meter Status
Pressure transmitter 1: Single output 4 ~ 20mA current load capacity of 300 (two-wire system).
Temperature Transmitter 1: Single output 4 ~ 20mA current load capacity of 300 (four-wire system).
2.5 motor and pump parameters
Motor and pump parameters, such as shown in Table 1.
Table 1 motor and pump parameters
1 #, 2 # 1 # motor parameters, parameters of circulating water pump # 2 Water pump motor Model Y3556-4/YKK400-4
Model 14SH-9A Rated power 315kW rated power 315kW
Rated voltage 6kV rated flow 1170m3 / h
Rated Current 37.7A Rated lift 65m
Rated speed 1475r/min rated speed 1450r/min
Power factor 0.86 3 on-site debugging and problem solutions
3.1 to site Taking into account the limited field installation conditions, the scene decided to bypass frequency counter device and manually placed separately: the 1 #, 2 # conversion devices (single Dimension (mm) (W × H × D ): 3300 × 2574 × 1200) placed side by side in the converter room, while the bypass pump cycle counter is placed on the scene. This result placed the venue not only to solve the problem, but also to facilitate the operator; to live in recycled water that can be observed frequency converter transmission case, best of both worlds.
3.2 critical point pressure Reference desulfurization process requests of “pressure” is to ensure production of sufficient conditions for desulfurization, that pressure to 0.46Mpa, can guarantee the normal operation of desulfurization unit. Pump outlet pressure is too low, you can not overcome the potential energy of water, recycled water can not be sent to the cooling tower; pressure increases too high to pump water through the cooling cycle, the efficiency is not high. Therefore decided to adopt a “constant pressure” closed-loop control, adjust the frequency converter for a given frequency, the minimum pressure required to find process critical point, it is necessary to meet the technology demand pressure also ensures that the recycled water, so that the temperature difference and out of cooling tower t stable at between 4 ~ 8 . The trial demonstrated that when a given frequency is 43Hz, the pump pressure (0.51MPa) meet the technical requirements, temperature 4.92 , so the pressure set 43Hz as the critical point.
Debug parameter table shown in Table 2.
Table 2 debug parameter table 3.3 transmitter load capacity Because the field is only a single output of the pressure transmitter, and with a carrying capacity of only 300 , while the converter built-in PLC S7-200 type EM235 Analog Input Module The input resistance of 250 ; if the two converter analog input circuit in series, then the input resistance of the two EM235 shall be 500 , single pressure transmitter does not bring the two EM235 module, this option is not feasible. Therefore, the pressure transmitter site access to a single frequency device EM235 module using the S7-200 analog output module EM232 live the way real-time output pressure, with the output signal as Converters EM235 another analog input. Block diagram shown in Figure 2. This method does not increase in input costs (hardware) in the case, by rewriting PLC program to a PLC of the EM232 module # converter input all the way real-time pressure feedback signal, the pressure to solve the problem of insufficient load capacity of the transmitter to achieve a single Drag the two transducer pressure transmitter station of “closed loop” control.
4 energy-saving computing 4.1 Principle of Frequency Conversion of Energy
Shown in Figure 3, according to principles of fluid mechanics:
Figure 3 baffles regulating water flow and frequency regulation of energy comparison chart, H2-BC-H3 region comprising baffle adjustment for the conversion of water to save more power.
When using frequency control, it may need to rise by
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