Page 423 - Compression Machinery for Oil and Gas

402 SECTION III Applications

in the range of approximately 0.2MPa (in the case of blowers) to 19MPa in the
case of barrel compressors.”
Refinery process gases can be corrosive, such as sour crude, which has a
high sulfur content. Corrosive gases cause damage to the compressor flow path
and seals over time. Compressors in refinery applications are typically installed
outdoors unless extreme temperature environments require indoor installations.
The benefit of an outdoor installation is that there is lower explosion risk and the
installation cost is reduced by avoiding indoor safety requirements of gas mon-
itoring, fire suppression, and room-air cycling.

LNG Production

The International LNG trade is expanding at a rapid pace with LNG accounting
for approximately 9%–10% of global gas supply. Table 10.1 provides some
salient parameters of the current LNG market.
Converting natural gas to LNG is accomplished by chilling and liquefying
the gas to a temperature of 113K. When liquefied, the volume of the natural gas
is reduced to 1/600th of its standard volume. This allows the efficient transpor-
tation of gas using specialized LNG tankers. The size of a liquefaction facility is
usually stated in millions of tons per annum (MTPA). One metric ton of LNG is
equivalent to 54.8 GJ of gas. The refrigeration is accomplished using several
commercially available processes that typically involve the successive chilling
of the feed gas to lower temperatures using mechanical refrigeration systems
utilizing large refrigeration compressors. The compressors are typically driven
by gas turbines ranging from 30 to 120MW.
LNG compressors include the following:

l main refrigeration compressors
l boil of gas compressors
l end flash compressors
l regeneration compressors

TABLE 10.1 LNG Market

Parameter Value
Global LNG trade in 2016 258 MT
Global nominal liquefaction capacity 340 MTPA
LNG shipping fleet 439 ships
Share of LNG in global gas supply 9.8%
Data from IGU World LNG Report (2017) https://www.igu.org/sites/default/files/103419-World_
IGU_Report_no%20crops.pdf.