Canned motor pump technology for cryogenic application in chemical and petrochemical industries
The largest gas processing facility in Russia and one of the biggest in the world was launched by Vladimir Putin, President of the Russian Federation, in the autumn of 2015. It will serve as an essential link in the process chain of natural gas supplies to China via the Power of Siberia gas pipeline. The plant will have the design output of 42 billion cubic meters of feed gas per year.
Furthermore the plant is meant to extract up to 2.5 million tons of ethane fraction per year, produce up to 1.7 million tons of liquefied hydrocarbon gases per year and produce up to 60 million cubic meters of helium per year at one of the largest helium extraction facilities in the world.
The core process equipment for cryogenic recovery of helium and natural gas liquids extraction from gas as well as nitrogen rejection units is provided by a world leading supplier of industrial, process and speciality gases.
This supplier, a leading player in the international plant engineering business, trust in using canned motor pumps for their plants. One of their items, a demethanizer reflux pump, should handle approx. 900 m3/h @ 100 m liquefied methane combined with nitrogen at -120°C. This mixture leads to a density of 374 kg/m3 and a vapour pressure of 27.1 bar(a).
Furthermore the very low viscosity of 0,046 mPas, the NPSHA value of 1.7 m at LLS and the maximum allowable working pressure of 48 bar @ -196°C/60°C with test pressure 75 bar have to be considered. By the way, the specification class API 685 (2nd Edition), the material class A-7 or A-8 and the preferred submerged arrangement were a part of the requirement.
Due to the location of the plant it is mandatory to provide not only best available technology based on a minimum outside temperature of -52°C but also the corresponding documents such as EN13445 and TR CU for equipment.
HERMETIC holds a world-leading position in the global market of seal less pumps and is well-known for engineered to order pumps. We implemented our know-how to reach all customers requirements.
Due to the very low viscosity we arranged a vertical design, supported by a permanent magnetic bearing. This unique feature, designed by HERMETIC, leads to an independence of intermediate operation with high start stop frequency, unstable and fast changing operation conditions, gas/degassing and low rotation speed by variable frequency drive.
For the flow/head conditions we used a multistage pump type in stainless steel. These standard hydraulics up to PN100 allows a wide range of application. The suction pot in stainless steel with an inner diameter of approx. 1.5m is designed in PN64.
Based on a rotordynamics software a torsional analysis, a linear lateral analysis including an unbalanced response analysis had been carried out. As a result of the calculations it had been proven that the pump operates below first torsional mode and there is enough separation margin from 1 time and 2 times the operating speed, grid frequency as well as impeller vane passing frequency. In this respect the pump meets the requirement of API 685 2nd Edition.
At the end the complete equipment with an outer dimension of 2,4m x 2,4m x 4,6m and a total weight of 16 tons were designed, produced and delivered.
Considering all requirements it was challenging for HERMETIC. However with our submerged canned motor pump type TCAMF 90/3 N85z-4 with suction pot we could meet all requirements and additionally exceed customers expectations.