process design solution to balance initial monetary
investment with the long-term expense of owning and
operating the plant, according to available and suitable
technical solutions.
Using a steel PFHE as an
intercooler
Some large compressors require several MW of power to run.
Consequently, a slight improvement in efficiency can result in
large energy savings.
Figure 1 represents the pressure-volume diagram for four
different compression system configurations:
The adiabatic curve represents the isentropic
compression, with only one unique staged compression,
but requires the maximum work.
The isothermal curve, which represents the ideal
single-staged compression, at constant temperature,
requires the minimum work. But this case is only
theoretical and not possible in practice.
The brown curve shows how a multi-stage compression
system can increase overall efficiency of that system. The
compression curve moves towards isothermal by means of
standard intercoolers between each compressor stage. The
cooler the gas is, the better the compression efficiency is.
The red curve shows the improvement brought by the
use of more efficient intercoolers. The compression curve
moves closer to isothermal, which means that the overall
gas compression efficiency rises significantly.
In brief, efficient heat exchangers used as an intercooler
have several advantages on the overall gas compression
system performance, including the following:
Compression temperature profile approaches close to
ideal isothermal functioning, so the work done by the
compression system is reduced. Thus, less power is
required to deliver the same quantity of gas at a given
delivery pressure.
It increases the volumetric efficiency for the same
compression ratio.
The machine can be smaller.
Mechanical problems are minimised due to a lower
operating temperature.
Effects from moisture are better dealt with by favouring
the drainage of condensate at each compression stage.
The lubricating system is less impacted by high delivery
temperature.
The low pressure cylinder may be lighter.
Conclusion
BSSHXs respond to more stringent specifications, and
seek to find the best compromise between both technical
performance and best return on investment (ROI). They are
particularly suitable for offshore gas compression systems.
The heat exchangers’ options are fully customisable to find
the best compromise between thermal and pressure drop
performances, cost and weight, while optimising availability, in
order to improve the overall process solution.
Proven LNG
Capabilities
Our 20,000-strong Oil & Gas professionals deliver end-to-end
services to our clients in the global LNG sector.
We offer capabilities in:
›
Liquefaction plant build
›
Completions and commissioning
›
Non-process infrastructure
›
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Operations and maintenance
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Re-gasification and receiving terminals
›
Off-sites and utilities
›
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