[Abstract] This paper briefly introduces the damage situation of the outlet check valve of high pressure liquid ammonia pump in urea plant and presents the solution. Key words: Leakage of liquid ammonia check valve I. Overview High pressure liquid ammonia pump P101A / B is the key equipment for urea plant. It was introduced in the 1980s from the United States SUNDSTRAND HMP-5112 high-speed centrifugal pumps, working conditions The opening design pressure is 27MPa, high-speed shaft speed is 20445R / min; the outlet check valve is a single valve swing type high pressure self-sealing check valve, the structure and basic parameters as shown in Table 1, the main role P101A / B in order to automatically shut down when the pump to prevent high-pressure media backflow caused by pump impeller reversal, P101 pump protection from the role. After more than 10 years of operation, two valves seriously leak, and P101A pump outlet check valve leakage, the two failure if not resolved in time, will seriously affect the safety of urea plant, so its disassembly repair, Because of the pump outlet check valve both inside and outside the drain, the following on the valve as an example to introduce. Second, the maintenance of the valve problems (1) the valve long-term due to the valve core is in working condition, so that the valve shaft wear hole into an oval, resulting in valve sinking, as shown in Figure 1, frequently open the valve seat seal Under the surface of serious damage, resulting in serious leakage, as shown in Figure 2. (2) The valve due to manufacturing defects and media corrosion and other reasons, the outer part of the valve body cracks appeared, leading to liquid ammonia leakage, as shown in Figure 3. Third, the maintenance program As the valve for the welding valve, subject to the inspection time, can not be offline repair. Decided to use on-site repair method to repair. Repair for leakage and leakage in two aspects at the same time: 1. Leakage repair program (1) with a small electric grinder manually seal the valve body seal surface cracks, while the surface coloring test until all the cracks and defects eliminated. (2) use A402 electrode (chrome 26 nickel 21 stainless steel electrode), with hot spot welding repair valve body sealing surface grinding Department. (3) Using a small electric mill manual grinding welding, so that the height of the valve body surface flush with the basic. (4) Production of inner ring grinding ring, shown in Figure 4. (5) with the grinding ring made by hand to seal the surface grinding, grinding the inner diameter: 160.7mm. (6) According to the inner diameter of the ring after the seal ring, as shown in Figure 5. 2. Internal leakage repair program (1) with a portable grinder seat sealing surface (see Figure 2). Make sure it returns to a circle in the presence of cemented carbide. (2) Find the original center of the shaft center hole through the four-card positioning on the lathe, meanwhile reaming the hole, as shown in Figure 6. (3) car system two rings (1Gr18Ni9Ti) set in the reaming. To ensure that the same in the center of the case, with a reasonable fit with the shaft, and spot welding fixed, as shown in Figure 7. (4) car through the shaft (1Gr13). (5) welded with tungsten carbide D547 molybdenum valve head, according to the valve seat after grinding repair valve head sealing surface. (6) After trial with Hongdan test to ensure its sealing. IV Conclusion In accordance with the above program on the high pressure liquid ammonia pump P101 outlet check valve for overhaul, a good solution to the valve leakage problem, after more than a year of operation, the use of good results, the maintenance of the same type of plant high pressure only Valve and other self-sealing valve has some reference.
Chemical Industry Mass Flow Meter
Sealand is a professional supplier of Chemical Mass Flow Meter, Chemical Mass Flowmeter, Chemical Flowmeter, Chemical Flow Meter, Chemical Coriolis Meter, ATEX, IECEx & CE approved.
The meter can work with a pulse receiver(Count). The connection is as follows. The
resistance value is up to the cable length & the max. input pulse frequency of receiver.
Current 10mA is suitable for most receivers; however, you can reduce the resistance value
when the cable is long. The max. current could be 50mA. Please use the fixed frequency
output function to check if the cable length & resistance value is suitable.
Please check following items before operation, and operate according to relevant rules.
a) If the meter is damaged during shipment and installation;
b) If the voltage is same as marked on nameplate;
c) If the fuse is correct;
d) If the meter is grounded properly.
e) If the Meter SN on the nameplate of sensor and transmitter are the same.
If everything is fine, please open all valves, make the pipeline full of liquid and then power on
the meter for warm-up for 20min before operation. Finally, conduct zero calibration after first
start, and shall do it again if the meter is moved to another site.
Preparation for zero calibration:
a) Power on the meter for approximately 20min for warm-up;
b) Run the process fluid through the sensor until the sensor temperature reaches the normal
process operating temperature.
c) Close the shutoff valve downstream from the sensor.
d) Ensure that the sensor is filled with fluid and the process flow has completely stopped.
Chemical Mass Flow Meter, Chemical Mass Flowmeter, Chemical Flowmeter, Chemical Flow Meter, Chemical Coriolis Meter
Zhejiang Sealand Technology Co., Ltd. , https://www.sealandflowmeter.com