Surgil ESIA Report - Volume III - EKN

“O’ZLITINEFTGAZ”
open joint-stock company
FS «Complex development of Surgil field
with extracting of valuable components»
Some mercury was detected in feed gas. Design project value of 900ng/m 3 was accepted for the
further designing process. Technical specification sets the mercury content in treated gas to be
10ng/m 3 .
Dehydrogenation and Mercury Removal Unit – MRU (Zone 104)
Compressed feed gas is cooled and dried.
Dried feed gas leaves the dehydrogenation units and enters Dried Feed Gas Heater where it is
heated to the temperature 5 o C above dew point to avoid condensation and adsorbent damage. Then
dried feed gas is routed to reactor for mercury removal. Feed gas is purified by the reaction between
mercury and adsorbent resulting in mercury sulfide formation.
In the bottom of adsorber feed gas pass through the cartridge filter to get rid of solid particles.
The filter should provide 10 micron filtering.
Ethane Recovery Unit (Ortloff) (Zone 105)
After purification and drying feed gas is sent to ERU. Before ERU feed gas is divided into two
flows. The first flow is routed to reboiler in demethanizer. The first flow rate is adjusted by the
temperature control in the bottom of demethanizer and the liquid methane content in the bottom of
demethanizer. Then the first flow is sent to the secondary reboiler in demethanizer where it is cooled
with the bottom liquid of demethanizer. The second flow is fed to exchanger for cooling with residual
gas. Two flows are further combined again and sent to separator to remove condensed liquids.
Then one flow is directed to turbo-expander/compressor for pressurizing to get the proper inlet
pressure.
The overhead reflux flow for demethanizer is obtained by the cooled and condensed recycled
residual gas. This cooled flow then vaporized and expanded to get working pressure value and fed to
demethanizer as reflux flow. Such unsaturated reflux flow allows RSV process to generate the product
with extremely high content of ethane.
Deethanizer is a reflux fractionation column where overhead ethane product with propane, LPG
and heavy bottom products are obtained. These bottom products are then sent to Fractionation Unit
(Zone 107).
Sales gas Compression Unit (Zone 106)
After compression in turbo-expander/compressor residual gas flow is routed to Sales Gas
Intercooler. Part of the flow is recycled and the other part is sent to the plant battery limit.
Fractionation Unit (Zone 107)
Deethanized bottom product is processed in Fractionation Unit. This unit consists of LPG
fractionation column, LPG fractionation column condenser, LPG fractionation column reflux drum and
reflux pump. Fractionation column operation is to LPG stream (overhead liquid product) generation.
Bottom product is an unstable gas condensate which contain C5+higher components.
Overhead gas in fractionation column is cooled with the air and is finally condensed at 50 o C in the
fractionation column condenser. LPG product is then fed to the drum.
Unstable Condensate Purification Unit and Mercury removal System (Zones 104 and 114)
Unstable condensate from Surgil field is sent to Unstable Condensate Purification Unit. This unit
consists of vaporizer and condensate stabilizer.
This unit recovers volatile components from feedstock. In fractionation column there stabilized
Book 5. Declaration of environmental impact concerning UGCC construction
15