Pumps – Processes
Reexamination Certificate
2000-01-27
2001-08-21
Thorpe, Timothy S. (Department: 3746)
Pumps
Processes
C417S054000, C417S244000
Reexamination Certificate
active
06276902
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a compression system comprising at least one single-phase compression unit and at least one multiphase compression unit.
The invention is for example intended for fluids F
1
and F
2
, one of the fluids, F
1
, being essentially gaseous, and another fluid, F
2
, essentially liquid or multiphase, the total volume flow rate of these two fluids Qt=Q
F1
+Q
F2
exceeding notably the treating capacity of the multiphase compression unit.
In the description hereafter, what is referred to as a single-phase or multiphase compression unit is an assembly comprising one or more bodies, each body comprising one or more sections, each section comprising one or more stages.
Similarly, the term “water” refers to fresh water or salt water, such as seawater or formation water.
The multiphase compression unit can comprise single-phase pumping sections and multiphase compression sections.
The system according to the invention can be used for compression of fluids for which the value of the ratio of the volume flow rate of the gas phase to the volume flow rate of the liquid phase (GLR for short) is greater than a limiting value ensuring good two-phase efficiency of the multiphase compression unit (the ratio being considered at the inlet).
The invention can also be used for a mixture of fluids comprising a very large quantity of gas in relation to the quantity of liquid, and when the density of this mixture is too low to obtain sufficient compression ratios in a multiphase compression unit.
BACKGROUND OF THE INVENTION
The prior art describes various devices for compressing a gas phase and for pumping a liquid phase, or for compressing a gas phase and a multiphase phase.
One procedure consists in using suitable single-phase equipments for each phase, associated with phase separation devices.
Single-phase compression of a gas and pumping of a liquid at high pressure generally requires a large number of equipments, for example one or more compressors for compression of the gas, one or more heat exchangers for cooling the gas after compression, one or more pumps for pressure rise of the liquid, one or more devices for mixing the phases, a gas and liquid separator placed upstream from each compression section, pipe connections, valves, instrumentation and a complex regulating system for keeping the assembly in good working order. Such a system is relatively unwieldy and expensive.
It is also well-known to compress a fluid comprising a gas phase and a liquid phase in order to mix them at high pressure, by means of a positive-displacement or rotodynamic type multiphase compression device equipped with helical axial flow impellers. The major drawback of positive-displacement machines is that they are heavy and bulky.
SUMMARY OF THE INVENTION
The layout of the compression system according to the invention consists in judiciously and suitably associating at least one single-phase compression unit situated for example upstream from at least one multiphase compression unit.
One or more integrated mixing and cooling sections can also be associated in the system.
The invention relates to a system for compressing one or more fluids (F
1
, F
2
), at least one of the fluids, F
1
, being essentially gaseous. The system is characterized in that it comprises in combination:
at least one single-phase compression unit for fluid F
1
, said unit being connected to a supply line delivering an essentially gaseous fluid,
at least one multiphase compression unit for both fluids F
1
and F
2
, said multiphase compression unit comprising at least one supply line delivering the essentially gaseous compressed fluid F
1
and at least one supply line delivering fluid F
2
, a fluid discharge line,
said single-phase compression unit being placed upstream from said multiphase compression unit,
said single-phase compression unit is for example so dimensioned that the value of the total flow rate of the fluids Qt=Q
Gi
+Q
Lj
is less than or equal to the value of the flow rate Qham acceptable by the multiphase compression section in the multiphase compression unit, with
Q
Gi
the value of the volume flow rate of the gas phase considered before the inlet of the multiphase compression section, and
Q
Lj
the value of the volume flow rate of the liquid phase considered before the inlet of the multiphase compression section.
The single-phase compression unit can be suited to allow operation of the multiphase compression unit within a given two-phase efficiency range.
It can comprise a device for mixing at least part of compressed fluid F
1
and of fluid F
2
upstream from the multiphase compression unit, fluid F
2
being used for cooling fluid F
1
compressed in the single-phase compression unit.
It comprises for example at least one means allowing to cool the compressed gas by means of an auxiliary fluid.
The invention also relates to a method for compressing several fluids F
1
and F
2
, at least one of the fluids, F
1
, being essentially gaseous. The method is characterized in that it comprises in combination at least the following stages:
a) sending essentially gaseous fluid F
1
to a single-phase compression unit, and
b) sending compressed fluid F
1
and fluid F
2
to a multiphase compression unit,
c) compressing for example the essentially gaseous fluid so as to obtain a total volume flow rate value Q
Gi
+Q
Lj
that is less than a flow rate value Qham acceptable by the multiphase compression unit.
The gas phase is for example mixed at least partly with the liquid phase before stage b) by using fluid F
2
in order to cool essentially gaseous fluid F
1
.
The system and the method according to the invention are applied for compression of soluble gas(es) and of their liquid solvent, the total volume flow rate of these two fluids exceeding the capacities of the two-phase compression unit, or for compression of acid gases and water, the total volume flow rate of these two fluids exceeding the capacities of the two-phase compression unit.
The compression system according to the invention notably affords the following advantages:
the number of parallel-connected multiphase compression sections required for treating fluids having a high total volume flow rate is reduced,
the number of series-connected multiphase compression sections required for treating fluids having too low a density is reduced,
the number of commonly used single-phase compression and pumping equipments is reduced,
maintenance of the assembly is simplified and less expensive,
the efficiency is increased in relation to a compression system comprising only two-phase machines.
REFERENCES:
patent: 4325712 (1982-04-01), Arnaudeau
patent: 4653268 (1987-03-01), Nakamura et al.
patent: 5290151 (1994-03-01), Orlando
patent: 5377714 (1995-01-01), Giannesini
patent: 6142743 (2000-11-01), Charron
patent: 6171074 (2001-01-01), Charron
patent: 6174440 (2001-01-01), Charron et al.
patent: 2424473 (1979-11-01), None
patent: 2424472 (1979-11-01), None
patent: 2239676 (1991-07-01), None
patent: 2312929 (1997-11-01), None
Antonelli Terry Stout & Kraus LLP
Gray Michael K.
Institut Francais du Pe'trole
Thorpe Timothy S.
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