![<?echo $_SERVER['SERVER_NAME'];?>](/template/twentyseventeen/skin/images/header.jpg)
Deliver liquefied petroleum gas.
If the structure of the shield pump is changed as shown in Fig. 4, that part of the liquid used to lubricate the bearing and the cooling motor is directly returned to the vapor phase region of the liquefied gas storage tank by the high pressure region of the impeller through the lubricating bearing and the cooling motor without returning to the inlet 3 Then even if a small amount of vaporized bubbles are brought to the vapor phase zone of the storage tank, the above phenomenon can be avoided.
5 Performance test and field operation According to the above analysis and design, make 1 prototype. The parameters are: Q prototype passes the water cavitation performance test, the result is NPSH 0.5m, although it is 50% lower than the original expected performance of 1.0m, it still seems to be unsatisfiable. Design requirements, but because the NPSH measured value is measured under the conditions of room temperature and clean water, the test and the field indicate that the pump is actually transporting hydrocarbon medium, NPSH R medium R water R, that is, when actually transporting liquefied petroleum gas The NPSH R medium is much lower than 0.5m. Due to the limitations of the test conditions, there is no exact data. Can only be verified by trial run.
In fact, at the actual test run on site, the lowest liquid level in the tank to the center height of the pump is only 0.7m (there is almost no residual liquefied petroleum gas in the tank), that is, the original NPSH still has a safety margin, which fully meets the design requirements. The pump is operating normally after delivery. Since then we have provided the same pump for the company and other companies.
6 Concluding remarks (1) Since the vaporization pressure of liquefied petroleum gas varies greatly with temperature, liquefied petroleum gas is the most difficult to handle in the pumping liquid. If it is installed on a car tanker, the NPSH of the pump is the key.
(2) This paper solves the problem of NPSH during liquefied petroleum gas transportation. Although it is carried out according to NPSH during clear water transportation, it fully considers the characteristics of NPSH during liquefied petroleum gas transportation and the hydraulic loss of imported pipeline. Although there is no definitive data, practice shows that the expected result is solved in solving the contradiction of NPSH.
Shanghai Riji Shield Pump Co., Ltd., No. 91, Jingyi Road, Jinshanwei Petrochemical Zone.
The failure of the air compressor for scorching eliminates the cause of weld cracking failure between Gutongsheng of Guangzhou Petrochemical Ethylene Plant, and introduces the troubleshooting method.
1 Fault introduction A single air compressor of a vinyl plant air compressor (bit number C 1402) is a domestic 2D12 88/11 two-row symmetric balance piston compressor. The first-stage cylinder is double-acting, second and third. The cylinder is stepped and driven by a motor. Performance parameters, transmission system and cylinder arrangement are shown in Figure 1.
During the period from July to November 1997 (the actual operation of the unit was 1 month), the three-stage inlet piping of the newly installed scoring air compressor was strongly vibrated, resulting in a three-stage inlet buffer tank inlet and outlet flange reinforcement. The weld between the plate and the tank is cracked three times, which seriously affects the safe and smooth operation of the device. In April 1999, after more than 500 days of shutdown, the plant was overhauled. In order to eliminate the failure of the unit, the air compressor was inspected and repaired, and the three sections of the inlet pipeline were partially modified.
Performance parameter series temperature (°C) suction discharge suction discharge speed stroke power normal pressure normal temperature 2 failure cause analysis From the disintegration inspection situation, the unit's first, second and third stage cylinders and pistons are severely pulled, the first stage cylinder at the top wear area Up to 2, the cylinder wear area is up to 200cm. The third-stage cylinder and the lower half of the piston have a longitudinal pull mark with a depth of 1mm. The swing of the secondary piston rod is seriously exceeded. First, the secondary piston rod is seriously worn at the packing (top), the coating has been worn away and the corrosion is severe. The piston ring and the piston support ring are worn seriously. The coupling end of the main shaft is broken. The crankcase has the level of the crankcase, and the first and second crosses. The level of the head chute and the level of the first, second and third cylinders are all seriously exceeded. Specific measurement data ~ 5. At the same time, cracks were found in the weld between the flange of the inlet flange of the three-stage inlet buffer tank and the tank.
Unit level cylinder level crankcase level cross head level 1 level 2 level 3 east side west level 1 level allowed value maintenance before overhaul over range bearing pad clearance main shaft tile level 2 east side west side big head tile small head tile head The allowable value of the repair of the tile head tile before the overhaul is seen from the above-mentioned maintenance situation. Because the level of the unit is seriously out of tolerance during the first installation, the cylinder and the piston are pulled, the piston rod and the stuffing box are worn, and the unit is generated. The vibration is due to the fact that there are eight 90° right-angle elbows in the three-stage inlet line of the unit, and the support of the pipeline is a thin iron tube with poor rigidity. No damping pad is added between the pipe clamp and the pipe. In this case, When the pressure and velocity in the pipeline fluctuate, the pulsation of the airflow is very likely to cause vibration of the piping system.
Piston rod swing degree 1st level horizontal vertical allowable value horizontal vertical allowable value inspection before repairing alignment centering data radial axial allowable value inspection before repairing as shown in Figure 2, a section of equal section elbow, if the airflow inside the tube Is stable, the force at both ends of the elbow is F = P is the inner diameter of the pipe), and the resultant force R of the two forces is obtained by the geometric relationship: if the airflow in the pipe is pulsating, the unevenness of the pressure pulsation is δ, then The pressure pulsation amplitude value is: the impact of the airflow pulsation on the elbow, the amplitude of the impact force is: δ=4 for the pressure unevenness of the unit, and the inner diameter of the pipe=0.57 MPa, then the airflow impact force is obtained from the above formulas: Each 90° right-angle elbow has a 1581N force acting on the pipe elbow. The unit has eight 90° right-angle elbows from the second-stage outlet to the three-section inlet, so the impact of the airflow on the pipe will also cause Pipe vibration.
It can be seen from the above analysis that the three-stage pipe system of the unit has strong vibration, and the main cause of multiple cracks in the weld is that the unit is out of level, and there are too many elbows in the pipe, the pipe support rigidity is insufficient, and the pipe card design is not reasonable.
3 Fault elimination method For the problem of the level difference of the unit installation, the secondary grouting of the unit is knocked out, all the anchor bolts of the loose motive group, the horns are added and removed, the fuselage is re-leveled as required, and the spot welding horn is leveled. , for secondary grouting. After the fuselage is leveled, the three cylinders are leveled separately. During the leveling process of the three-stage cylinder, due to the seriousness of the level, the padding adjustment is performed on the joint surface of the cylinder to make the level meet the requirements. After the fuselage is re-leveled, the inlet flange of the first, second and third sections of the buffer tank and the outlet flange of the cylinder are seriously misaligned, and the support of the outlet buffer tanks of the first, second and third sections is loosened, and the flange is re-fixed after being aligned. To eliminate pipe stress. Finally, the unit is centered as required.
For the cylinders and pistons that are napped, since there are no spare parts, they are not replaced during the inspection, only they are polished. The worn piston rods are electroplated and repaired. The damaged consumables are replaced. The valves that have been inspected and cannot be cleaned are replaced. Grindable for grinding.
In order to reduce the impact of the airflow pulsation on the pipeline, the pipeline elbow and the direction are appropriately modified, and the pipe clamp and the pipeline support are re-adjusted.
4Reconstruction effect and use situation On August 16, 1999, the unit was tested after repair and maintenance. The whole test run was carried out from empty load to full load. The unit was running normally during the test run and the vibration was small (see Table 6). The mechanical performance of the unit is normal except that the first and second cylinders are worn more seriously and no parts are replaced, resulting in a slightly lower outlet pressure and a higher outlet temperature.
After the unit maintenance vibration data time one cylinder head three cylinder head three-stage inlet buffer tank inlet flange allowable value remarks unfilled valve first-stage air valve installed two-stage air valve installed three-stage air valve installed load Since the normal operation of the test drive unit since its official operation in September 1999, the vibration value has been below the allowable value of 250μm, which is very stable, and the three-stage inlet buffer tank has no cracks.
Gutongsheng 510700 Guangzhou Huangpu Guangzhou Petrochemical Ethylene Plant Mobility Department Welcome to subscribe to welcome submissions Welcome to advertise
Plastic mold is a combination mold used for compression molding, extrusion molding, Injection Mold Processing, blow molding, and low foam molding.
Plastic Mold,Plastic Molds,Plastic Mould,Plastic Moulds
Dongguan Anding Technology Manufacturing Co., Ltd , https://www.cn-moulds.com