当前位置: Home / Faq / Large air separation FAQ /

Adjustment of seal gas pressure and flow in liquid nitrogen pump

Adjustment of seal gas pressure and flow in liquid nitrogen pump
Jul 18, 2023
Author: DEAR AST
Question Reply

In the internal compression process air separation plant, we generally select the the multistage centrifugal pump as the liquid nitrogen pump. In order to ensure the stable operation of the liquid nitrogen pump, the pump seal mostly adopts the structure of gas-filled labyrinth seal.

 

The seal gas needs enough flow to warm the cryogenic liquid leaking from labyrinth seal. When the seal gas flow decreases to a critical point, the exhaust temperature of the seal gas will drop greatly and cause the interlock shutdown of the pump. With the pump running in the unstable state for a long time, the labyrinth seal will be worn and the gap will be increased, resulting in the increase of seal gas consumption, seal mixture outlet with liquid phenomenon, and causes the exhaust temperature of seal gas to decrease. In addition, the blockage of inlet pipeline filter by mechanical impurities and impurities in the filter screen of self regulating valve will also cause the seal gas flow to be too low.

 

The use principle of seal gas is not only to prevent liquid leakage along the outside of the pump, but also not to allow too much seal gas into the pump, resulting in the liquid nitrogen pump with gas phenomenon. It is suggested that the seal gas pressure can be adjusted by adding self regulating valve. When adjusting the seal gas pressure, it is necessary to ensure that the seal gas inlet pressure is higher than the labyrinth inlet pressure, which is 0.1-0.4Mpa, and the labyrinth inlet pressure is greater than the mixed gas pressure at the labyrinth outlet, which is  0.1-0.2Mpa. In order to prevent the equipment from being damaged by low temperature, it is necessary to ensure that there is no leakage of cryogenic liquid at the labyrinth seal. It is suggested to set a temperature sensor on the side near the pump body in the coupling guard to measure whether there is leakage at the sealing point, so as to give an alarm in time.

DEAR Air Separation Solve YourAdjustment of seal gas pressure and flow in liquid nitrogen pumpYou can also learn about otherLarge air separation FAQ about DEAR Air Separation, and solve the problem for you.
Didn’t find the problem encountered?
Please contact live chat or email for quick help.
Related FAQ
More Related FAQ
Oxygen product: liquid oxygen is pumped out from the lower tower plate of the low pressure tower and sent to the storage tank, the inner compressed oxygen pump is placed next to the liquid oxygen storage tank, the liquid oxygen extracted from the storage tank is pressurized by the oxygen pump and sent out after gasification and reheating in the main heat exchanger to get the required oxygen product in liquid air separation plant. The nitrogen product is pumped from the top of the pressure tower...
2024.03.28
The most common failure of the liquid oxygen pump is the leakage of the seal. For the structure of mechanical seal, the key is the bad contact of the sealing surface of the dynamic and static ring of the friction pair. It is related to the grinding quality of sealing surface, the assembling quality of pump shaft and bellows, and the material of friction pair. For the labyrinth type seal structure, it is related to the adjustment of the seal clearance and the pressure of the seal gas. Other faults and solutions are as follows: 1) the pump can't start: the current is blocked. The circuit should be rechecked to switch on the current; the rotor gets stuck or the gap is too small. The pump should be removed for inspection and the clearance should be adjusted. 2) no drainage after starting: the steering of the pump is opposite. Check the motor steering, change the power wiring; the pump is not fully precooled, gas is generated. The pump should be stopped and fully precooled again; the inl...
2024.03.27
Need more information?
Contact us for more details about our air separation equipment, solutions and services.
Products
  • Large air separation
  • Small air separation
  • High purity nitrogen air separation
  • Liquefaction air separation
  • Complete air separation
  • Biogas purification
  • Air separation parts
Need more information?
Tel:+86-19837850537
© Kaifeng DEAR Air Separation Industry Co., Ltd.. All rights reserved.
Online
Inquiry
Email
Top