Huangdao Oil Depot is mainly engaged in importing, unloading, storage and transportation of imported crude oil. Through the 5 pumps, 6 pumps and 7 pumps of the first oil delivery team, the imported crude oil is supplied from the East-Yellow Line to the downstream refineries to provide power. With the significant increase in imported crude oil ashore on Huangdao Island, crude oil delivered through pipelines has also increased significantly. In 2004, the pipeline transportation was completed with 1233.94X104t, an increase of 315.95X104t compared with the same period of last year, with an increase rate of 34.42%. The three oil pumps of the first team of the oil transmission play an important role in pipeline transportation. 5 pumps, 6 pumps, 7 pumps are DZS250X340X4 multi-stage centrifugal pumps, rated flow is 800m3/h; rated head is 600m; rated shaft power is 1 630kW; equipped with motor power is 1800kW; rated voltage is 6000V; rated current 200A. Since it was put into use in November 2000, there has been a pump outlet valve opening of about 20%, the current has risen to the rated current of the motor, the maximum flow can only reach 600m3/h, throttling phenomenon of the pump is quite serious, Unable to work in an efficient area. Therefore, the pump is extremely vibrating during operation (noise up to 90dB). It often breaks the screw of the coupling guard, breaks the shaft of the pump and the motor, and leaks the connection between the pump and the vent line. Maintenance caused a lot of trouble.

After reviewing the pump performance test report and performance curve in the stochastic technical documents of the oil pump, the shaft power of the pump's rated operating point is 1630.56 kW, the shaft power of the high efficiency zone is 1 5671846 kW, and the matching pump motor power is 1 800 kW. According to the conventional and related standards, the supporting motor must consider a certain power margin. The motor = (1.11.2) pump. If the coefficient is 1.2, the W motor should be 1957.67 kW. If the coefficient is 1.1, the motor should be 1793.616 kW. It can be seen that the original motor power margin coefficient is 1.1, which is less than the normal power margin factor of the motor by 1.2, which is the main reason that the 5, 6 and 7 delivery pumps cannot work at full capacity.

2 Implementation of technological transformation According to the similar principle, any centrifugal pump can change its technical performance such as flow, head and shaft power by changing the diameter of the impeller.

Therefore, the impeller diameter of the cutting pump can be used to reduce the shaft power. Cutting impeller to change the technical performance of the pump has a short duration, investment, and quick, can be combined with the advantages of the pump overhaul.

Therefore, it was decided to reform the 5 pump first, and if the reform effect was better, then several other pumps would be reformed.

5 Calculation of the specific rotation speed of the fuel pump n The number of rotations of the motor with the pump, r/min; the rated displacement of the Q pump, m23/s; H - the single stage head of a pump, m. Formula (1) is calculated Out: nx = 119. The minimum diameter of the impeller after cutting calculation based on the relationship between the type of centrifugal pump and the number of revolutions (see Table 1, Table 2), we can see that the pump is the middle ratio pump, the maximum cutting amount of 0.15. (mln The minimum diameter of the impeller after cutting, mm. Checked by the random technical documents of the oil pump: D2 Table 1 Relationship between the type of centrifugal pump and the number of revolutions Pump type Meter type Centrifugal pump Type of low specific speed of the pump Low specific speed of rotation The relationship between the maximum cutting volume and the specific rotation speed of the impeller of the rotation table 2 is greater than the maximum cutting volume of the impeller 0.5074, which is far less than 0.15, and the efficiency of cutting the corresponding working point is approximately equal.

Before and after the transformation, the hydraulic conditions of the 5 oil delivery pump units are shown in Table 3. Through comparative analysis of the parameters before and after the transformation, it shows that after the transformation of the oil pump unit, the throttling loss is reduced by about 41%, the transmission volume is increased by 4.83%, and the pump efficiency is improved by 6%. The system efficiency has increased by 28.51%, and the reactive current has dropped by an average of 38.5A. Table 35 Comparison of the process parameters before and after the transformation of the oil pump unit Pump pressure Thousand pressure throttling Pump efficiency System efficiency Current May 16, May 22 5 On May 24th, May 26th, June 28th, June 28th, June 29th, June 30th, before and after the average transformation, the mechanical performance of the 5 oil-pumping units was shown in Table 4. Through the comparative analysis in Table 4, it showed that after the transformation of the oil-pumping units, the vibration, The mechanical performance such as noise has been greatly improved.

Table 45 Comparison of mechanical performance parameters before and after transformation of the oil pump unit Pump vibration Motor noise Motor noise Before and after the transformation of the impeller After the performance curve of the impeller After comparing the performance curve of the impeller before and after the pump (see below), it can be seen that the equivalent displacement Below, the lift of the pump is reduced after the impeller is cut. In this way, no throttling is needed in the daily operation to meet the requirements of the process, which effectively solves the problem that the head energy required by the East-Yellow line is lower than the energy head of the pump with which it is pumped, resulting in very severe throttling of the pump. The disadvantage is that the impeller cannot be restored after cutting.

According to the analysis results in Table 3, the throttling loss during operation of the 5th oil pumping unit is reduced by about 41%. The power loss due to throttling loss is calculated by formula (6): 5 The average power saving of the oil pumping unit is approximately 351.67kW. X. According to the annual operation for 6 months, the electricity saving is 1519214kW, ten, the electricity price is 0.67 yuan/kW, the ten calculation can save the cost of 101.78 million yuan, the total transformation investment is 65,000 yuan, and the investment recovery period is about 23d. In addition, when the pumping volume is greater than 950m3/h, there are also cases where two pump units operate at the same time to drastically throttle. After the same technological transformation, the resulting economic benefits should be randomly superimposed. After technical transformation, the mechanical performance of the DZS250X340X4 oil delivery pump unit has also been improved, reducing the vibration and noise of the unit and extending the service life of the pump unit.

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