Pumps – Combined
Reexamination Certificate
1999-01-28
2001-01-09
Walberg, Teresa (Department: 3742)
Pumps
Combined
C415S169100, C415S169200, C210S096100, C210S195100
Reexamination Certificate
active
06171074
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a compression-pumping system designed for a multiphase fluid comprising at least one liquid phase and at least one gas phase.
BACKGROUND OF THE INVENTION
It is well-known that it is possible to impart energy to a multiphase fluid or to a mixture of gas and liquid by means of various machine types.
Whatever the design of the rotodynamic pumps used, and more particularly single-phase type pumps, good results are obtained when the value of the gas-liquid volume ratio under real given pressure and temperature conditions (GLR in abbreviated form) of the fluid is low.
Pumping of a liquid-gas mixture by means of radial impellers is thus generally limited to gas proportions below 20%. This limit can be brought to about 30% in the case of radio-axial impellers and to about 40% with axial impellers.
The prior art also describes pumping devices having characteristics suited to pumping of a multiphase fluid. For example, the applicant's patent FR-2,665,224 describes a geometry of the cross-section of flow for a multiphase fluid that is delimited by two successive blades, suited to impart energy to a multiphase fluid in order to compress fluids whose GLR value ranges for example between 0 and 20.
However, the pumping or compression efficiency for such a fluid varies considerably according to the conditions in which the fluid notably is. This efficiency tends to decrease when the two-phase fraction increases and when the ratio of the density of the gas to the density of the liquid decreases. Besides, the single-phase performances of these impellers that serve as a reference for determination of the two-phase performances are substantially lower than those of radial impellers, in particular the efficiency and the manometric head delivered per stage.
Furthermore, it is often necessary to use several machines positioned in series in order to obtain the desired compression ratio.
Using several single-phase machines (pump and compressor) or several multiphase type machines leads to bulky and expensive compression installations.
SUMMARY OF THE INVENTION
The compression system according to the invention consists in including in the same device the elements required for separation of the liquid and gas phases and for compression of each of these phases. It notably consists in using a device comprising a pumping section and a compression section whose impellers are secured to the same shaft, these two sections are associated with a gas-liquid separator for producing an essentially liquid fluid and an essentially gaseous fluid. The compression system thus defined is associated with a control circuit. The separator has a reduced volume in relation to the prior art.
The present invention relates to a compression-pumping system for a multiphase fluid (GLR) comprising in combination at least the following elements:
a compression section suited to compress an essentially gaseous fluid,
a pumping section suited to impart energy to an essentially liquid fluid,
a shaft A,
seal means between the compression section and the pumping section,
a separator allowing to obtain an essentially liquid fluid and an essentially gaseous fluid,
various delivery or discharge pipes for the multiphase fluid and/or each of the phases of said multiphase fluid coming from the separator.
The system is characterized in that:
the shaft is common to the compression section and to the pumping section,
the pumping and compression sections are included in the same enclosure.
It comprises for example at least one system for controlling the level of liquid in the separation device.
The liquid level control system can comprise a means for detecting the liquid level and it allows to control and/or to act on the liquid and/or gas flows coming from the separator according to the level of the gas-liquid interface in the separator.
The control system can comprise a series of valves and bypass lines including at least:
a pipe for recycling part of the gas coming from the compression section, said pipe being equipped with a control valve,
a pipe for recycling a liquid fraction, said liquid fraction coming from the pumping section and said pipe being equipped with a control valve,
a detector allowing to detect the liquid level in the separator,
data processing and signal generation means (M).
The separator is for example a static separator.
The static separator can be associated with at least one of the following elements:
a helical pipe placed inside said static separator,
a first stage of the compression section suited for separation of the droplets and of the gas,
several disks (Dl, Dg) mounted on said shaft, said shaft extending in said separator over at least part of its length,
a cyclone type device,
said elements can be used alone or combined with each other.
The number of impellers for the compression section and for the pumping section and the specific speed of the impellers corresponding to the compression section are for example selected so as to have:
N
s
,
gas
N
s
.
liq
=
GLR
(
1.3
Nb
g
Nb
l
ρ
g
ρ
l
)
3
/
4
substantially close to 1.
The separator can be secured to the enclosure or included therein.
The system according to the invention advantageously finds applications for multiphase petroleum effluent transportation.
Using the system according to the invention notably allows to:
reduce the number of machines in comparison with single-phase and multiphase machines,
reduce the number of impellers in comparison with multiphase compression,
reduce the power consumption in comparison with conventional two-phase or multiphase machines.
REFERENCES:
patent: 2276824 (1942-03-01), Garruthers
patent: 4971529 (1990-11-01), Gannaway et al.
patent: 4981175 (1991-01-01), Powers
patent: 5051072 (1991-09-01), Yano et al.
patent: 5064452 (1991-11-01), Yano et al.
patent: 5085561 (1992-02-01), Yano et al.
patent: 5551845 (1996-09-01), Milam
patent: 5575615 (1996-11-01), Mohn
patent: 5580214 (1996-12-01), Mohn
patent: 5873709 (1999-02-01), Cornut et al.
patent: 2608705 (1977-09-01), None
patent: 2333139 (1977-06-01), None
patent: 2471501 (1981-06-01), None
patent: 2665224 (1992-01-01), None
patent: 9313318 (1993-07-01), None
Antonelli, Terry Stout & Kraus, LLP.
Institut Francais du Pe'trole
Pwu Jeffrey C
Walberg Teresa
LandOfFree
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