Lines of activities >  Complex designing >  Propane-butane recovery from natural gas

Propane-butane recovery from natural gas

In 1997, in Karshi, Uzbekistan, a plant was commissioned that was developed by specialists of LENNIICHIMMASH Ltd for production of 68 thousand tons per year of propane-butane-mixture, the plant capacity in terms of natural gas being 3.0 billion m3/year.

 
Source gas parameters:

 Pressure, MPa
4,8 - 5,0
 Temperature, deg C     
52
 
Products of processing are:
  • propane-butane mixture according to State Standard GOST R 52087-2003
  • liquefied hydrocarbon gases
  • high-pressure methane fraction returned to the gas-main pipeline after compressing in the recompression shop.
 
The propane-butane mixture recovery process is continuous, it uses the method of natural gas cooling and partial condensation by means of source gas expansion effect in a turbo-expander followed by rectification of produced condensate. External source of cold are not used.
 
The plant consists of the following units of:
  • Fine filtration
  • Pre-cooling
  • Expander
  • Deethanization column
  • Desired products making
  • Drainage tanks
  • Auxiliary equipment – pipelines and metal structures
 
Heat exchange processes in the plant run in vertical coil-tube, rigid-core heat exchangers and in horizontal straight-tube apparatus (water coolers). There are also heat exchange apparatus with coil (boilers) and straight(dephlegmators) tubes built into the columns. For cooling of hot flows, air coolers are provided. Mass exchange processes run in two plate-type rectification columns.
 
As reservoir apparatus, the plant uses separators, reflux tank and tanks for condensate collection, for storage of working fluids during the plant outage, and for drains.The size of the site occupied by the plant is 70x30 m2.
 
In July 2006 the construction of the plant for associated petroleum gas recovery by capacity of 3 billion m3 /year (UPG-3) fulfilled according to the LENNIICHIMMASH Ltd technology and project was completed and the plant was set in operation. The plant reached the rated capacity.
During creation of the separation technology the energy-conserving method of separation of associated petroleum gas with using of the turbo-expander unit developed by LENNIICHIMMASH Ltd (RF patent # 2225971, priority date 20.03.04) was applied.
 
The produced end products are:
  • methane fraction according to the standard OST 5140-93 – 2,8 billion nm3 /year
  • propane-butane technical (PBT) according to State standard GOST R 52087-2003 – up to 203 thousand t/year
  • BFLH according to the technical regulations TU 38.101524-93 – 27 thousand t/year
  • gasoline stable (GS) according to State standard GOST 20448-90 – up to 47 thousand t/year
 
The rated capacity of electrical equipment - 465 kW, that is in 3-5 times less than at the gas separation with using propane cooling cycle.
In-line equipment of the plant was supplied by LENNIICHIMMASH Ltd as well.
 
The plant consists of the following units of:
  • preliminary separation
  • gas dewatering and scrubbing (gas treatment)
  • pre-cooling with a turbo-expander
  • rectification
  • fire preheaters
  • system of coolant circulation.