US009046097B2

(12) United States Patent (10) Patent No.: US 9,046,097 B2

Scotti Del Greco et al. (45) Date of Patent: Jun. 2, 2015

(54) TEST ARRANGEMENT FOR A 73/112.05, 168; 29/407.01, 407.05,

CENTRFUGAL COMPRESSOR STAGE 29/407.09, 888.02, 888.024
See application file for complete search history.
(71) Applicant: Nuovo Pignone S.p.A., Florence (IT) (56) References Cited
(72) Inventors: Alberto Scotti Del Greco, Figline U.S. PATENT DOCUMENTS
Valdarno (IT): Libero Tapinassi, Rufina
(IT); Stefano Vanghi, Florence (IT): 3,876,326 A * 4/1975 Weitz ...... 415, 17
Filippo Gerbi, Sesto Fiorentino (IT): 4,156,578 A * 5/1979 Agaret al. ... 415/1
4,177,649 A * 12/1979 Venema ......... ... 62,209
Chiara Cinelli, Barberino di Mugello 4,275,987 A * 6/1981 Kountz et al. ................... 415, 17
(IT) 4,464,720 A * 8/1984 Agarwal ........ ... 701 100
4,546,618 A * 10/1985 Kountz et al. ................... 62,201
(73) Assignee: Nuovo Pignone S.P.A., Florence (IT) 4,581,900 A * 4/1986 Lowe et al. ... ... 62,228.1
4,608,833. A * 9/1986 Kountz ........................ 62,228.1
(*) Notice: Subject to any disclaimer, the term of this (Continued)
patent is extended or adjusted under 35
U.S.C. 154(b) by 272 days. FOREIGN PATENT DOCUMENTS
EP 2607711 A2 * 6, 2013 .............. FO4D 27.00
(21) Appl. No.: 13/719,329 JP 2002364553 A * 12/2002 .............. FO4B 51/OO
WO 2009 133017 A1 11, 2009
(22) Filed: Dec. 19, 2012 OTHER PUBLICATIONS
(65) Prior Publication Data Italian Search Report and Written Opinion dated Jul. 3, 2012 which
US 2013/O152357 A1 Jun. 20, 2013 was issued in connection with the Italian Patent Application No.
CO2011 A000069 which was filed on Dec. 20, 2011.
(30) Foreign Application Priority Data Primary Examiner — Essama Omgba
Dec. 20, 2011 (IT) .............................. CO2O11 AO069 (74) Attorney, Agent, or Firm — GE Global Patent Operation
(57) ABSTRACT
(51) Int. Cl. A system for testing a compressor is provided. The system
B23O 1700 (2006.01) comprises one or more compressors connected together in
GOIMI5/00 (2006.01)
F04B5I/00 (2006.01) series to a test compressor wherein an output of the test
F4D 27/00 (2006.01) compressor is connected to an input of a first compressor in
(52) U.S. Cl. the series, forming an overall loop, one or more process fluid
CPC .............. F04B5I/00 (2013.01); F04D 27/001 coolers in the overall loop, one or more orifices in the overall
(2013.01); Y10T 29/49764 (2015.01) loop, a control valve in the overall loop, and a first plurality of
sensors configured adjacent to a process fluid input of the test
(58) Field of Classification Search compressor and a second plurality of sensors configured adja
CPC. F04D 27/001; F04D 27/002; F04D 15/0088; cent to a process fluid output of the test compressor.
F04B51/00; G01F1/80; G01M 15/14
USPC .................... 415/30, 17:417/53; 73/861.353, 12 Claims, 6 Drawing Sheets

& Ex test icip

 US 9,046,097 B2
Page 2

(56) References Cited 6,918,307 B2 * 7/2005 Ohlsson et al. .......... T3/861.353

7,094,019 B1* 8/2006 Shapiro ........................... 415/27
U.S. PATENT DOCUMENTS 7,112,037 B2* 9/2006 Sabini et al. . 415, 118
7.841,825 B2 * 1 1/2010 Chen et al. ........................ 415.1
4,627,788 A * 12/1986 Keyes et al. .................... 415, 11 7.856,834 B2 * 12/2010 Haley .............................. 62,115
4,640,665 A * 2/1987 Staroselsky et al. .............. 415.1 8,037,713 B2 * 10/2011 Haley et al. ..................... 62,510
4,781,525 A * 1 1/1988 Hubbard et al. ................ 415.30 8,132,448 B2 * 3/2012 Nakamura et al. 73,112.02
4.949,276 A * 8/1990 Staroselsky et al. .......... TOO.282 8, 177.520 B2 * 5/2012 Mehlhorn et al. .............. 417/53
4,971,516 A * 1 1/1990 Lawless et al. ................... 415.1 8,522,606 B2 * 9/2013 Iannuzzi et al. 73,112.05
5, 195,875A * 3/1993 Gaston ........... 417.282 8,627,680 B2 * 1/2014 Haley et al. ..................... 62/498
5,355,691 A * 10/1994 Sullivan et al. ... 62,201 8,763,464 B2 * 7/2014 Emde et al. .. 73,659
5,553,997 A * 9/1996 Goshaw et al. ... 415/17 2002/0170349 A1* 11, 2002 Soneda et al. 73,168
5,599,161 A * 2/1997 Batson ........ ... 415/17 2003/0.133808 A1* 7/2003 Sabini et al. .................... 417/53
5,649,449 A * 7/1997 Algers ........... ... 73,168 2005/0031443 A1 2/2005 Ohlsson et al.
5,746,062 A * 5/1998 Beaverson et al. 62,228.3 2008/0101914 A1* 5/2008 Chen et al. ........................ 415.1
5,894,736 A * 4, 1999 Beaverson et al. ............. 62.230 2010/01628O2 A1* 7, 2010 Nakamura et al. ......... T3, 112.02
6,354,806 B1 3/2002 Bingham 2012/O121376 A1* 5, 2012 Huis In Het Veld .............. 415.1
6,487,869 B1* 12/2002 Sulcet al. ....................... 62.230 2012/0160021 A1* 6, 2012 Iannuzzi et al. ........... 73/112.05
6,503,048 B1* 1/2003 Mirsky .............................. 415.1 2014/0007663 A1* 1/2014 Berger ....................... T3, 112.05
6,648,606 B2 * 1 1/2003 Sabini et al. ... 417/53
6,691,047 B1 * 2/2004 Fredericks ...................... 702/47 * cited by examiner
U.S. Patent Jun. 2, 2015 Sheet 1 of 6 US 9,046,097 B2
U.S. Patent Jun. 2, 2015 Sheet 2 of 6 US 9,046,097 B2

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U.S. Patent Jun. 2, 2015 Sheet 3 of 6 US 9,046,097 B2

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U.S. Patent Jun. 2, 2015 Sheet 4 of 6 US 9,046,097 B2
U.S. Patent Jun. 2, 2015 Sheet 5 of 6 US 9,046,097 B2

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U.S. Patent Jun. 2, 2015 Sheet 6 of 6 US 9,046,097 B2

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 US 9,046,097 B2
1. 2
TESTARRANGEMENT FOR A BRIEF SUMMARY OF THE INVENTION
CENTRFUGAL COMPRESSOR STAGE
According to one exemplary embodiment, there is a system
BACKGROUND OF THE INVENTION for testing a compressor comprising one or more compressors
connected together in series to a test compressor. An exem
Embodiments of the subject matter disclosed herein gen plary embodiment continues with an output of the test com
pressor connected to an input of the first compressor in the
erally relate to methods and devices and, more particularly, to series, forming an overall loop. The overall loop contains one
mechanisms and techniques for testing a stage of a multiple or more process fluid coolers, one or more orifices and a
stage centrifugal compressor, and specifically testing the por 10 control valve in the overall loop. The system further com
tion of the performance curve associated with very low to Zero prises a first plurality of sensors configured adjacent to the
resistance or even a negative Suction head. process fluid input of the test compressor and a second plu
Centrifugal compressors are utilized extensively in many rality of sensors are configured adjacent to the process fluid
industries today across a wide variety of applications. An output of the test compressor.
important requirement in the manufacture, sale and delivery 15
According to another exemplary embodiment, there is a
of centrifugal compressors is providing a performance curve system for sizing an electric motor associated with a test
for the centrifugal compressor that is based on empirical data compressor, for optimally meeting the test compressor Star
tup requirements. The exemplary embodiment comprises an
with as little extrapolation as possible of the performance auxiliary compressor connected to the test compressor
curve. Using current methods and systems for generating a wherein the process fluid output of the auxiliary compressor
performance curve for a centrifugal compressor, a prior art is connected to the process fluid input of the test compressor
test system 100 is configured as shown in prior art FIG.1. A and a process fluid output of the test compressor is connected
centrifugal compressor 102 is connected to a gear box 104 to a process fluid input of the auxiliary compressor, forming
and an electric motor 106. The gear box 104 and electric a test loop. Next in the exemplary embodiment, one or more
motor 106 are sized based on the requirements of the cen process fluid coolers and one or more orifices are configured
trifugal compressor 102. Continuing with the prior art test 25 in the test loop. Continuing with the exemplary embodiment,
system 100 example, the outlet 108 of the centrifugal com a control valve is configured in the test loop. Further in the
pressor is piped through a control valve 110 and then a pro exemplary embodiment, a first plurality of sensors is config
cess fluid cooler 112 before returning to the centrifugal com ured adjacent to the process fluid input of the test compressor
pressor inlet 114. It should be noted in the prior art example and a second plurality of sensors is configured adjacent to the
that sensors for recording operating parameters such as, but 30
process fluid output of the test compressor.
not limited to process fluid temperature and pressure are According to another exemplary embodiment, there is a
placed proximate to the centrifugal compressor outlet 108 method for obtaining non-extrapolated empirical data asso
and inlet 114.
ciated with the performance characteristics of a compressor at
head values lower than head value losses associated with a
The centrifugal compressor 102 is then operated with the test loop connected to the compressor. The method comprises
control valve 110 at different positions such as, but not limited 35 connecting an auxiliary compressor to a main compressor in
to, ten percent to one hundred percent open in increments of a test loop Such that a process fluid output from the auxiliary
ten percent while data is collected from the sensors associated compressor is connected to a process fluid input of the main
with the prior art test system 100. The collected data is then compressor and a process fluid output from the main com
used to generate a performance curve for the centrifugal pressor is connected to a process fluid input of the auxiliary
compressor as illustrated in prior art FIG. 2. Prior art FIG. 2 40 compressor. The method further comprises installing a con
depicts a graph of Head versus Flow and shows the perfor trol valve in the test loop between the auxiliary compressor
mance curve 202 based on the data collected from the test and the main compressor, installing one or more process fluid
procedure with the control valve 110 in different positions of coolers and one or more orifices in the test loop between the
almost closed 204, partially open 206 and fully open 208. It auxiliary compressor and the main compressor, installing a
should be noted in the prior art test system 100 that the 45 first plurality of sensors in the test loop adjacent to the process
resistance experience by the compressor is at a maximum, fluid input of the main compressor, and installing a second
based on this test, when the control vale 110 is in the almost plurality of sensors in the test loop adjacent to the process
closed 204 position and at the minimum obtainable by this fluid output of the main compressor. Further in the exemplary
prior art test system when the control valve 110 is in the fully embodiment, the method comprises collecting data from the
open 208 position. 50
first plurality of sensors and the second plurality of sensors
The unknown section 210 of the performance curve is only while operating the test loop at conditions such that the main
compressor head is lower than head value losses associated
determinate based on extrapolation with the prior art test with the test loop.
system 100 and does not have a unique method of extrapola These and other aspects and advantages of the present
tion. It should be noted in the prior art system 100 that invention will become apparent from the following detailed
although the control valve is fully open 208, there are still 55 description considered in conjunction with the accompanying
losses associated with the design of the system based on the drawings. It is to be understood, however, that the drawings
presence of the components, and their associated losses, of are designed solely for purposes of illustration and not as a
the prior art test system 100. The combination of uncertainty definition of the limits of the invention, for which reference
in the extrapolation methods and the errors associated with should be made to the appended claims. Moreover, the draw
extrapolation at a boundary condition have led to market 60 ings are not necessarily drawn to scale and, unless otherwise
pressure to provide empirically produced specifications in the indicated, they are merely intended to conceptually illustrate
unknown section 210 of the performance and even beyond to the structures and procedures described herein.
a negative head location on the centrifugal compressor per
formance curve. BRIEF DESCRIPTION OF THE DRAWINGS
Accordingly, it would be desirable to provide designs and 65
methods that avoid the afore-described problems and draw The accompanying drawings, which are incorporated in
backs. and constitute a part of the specification, illustrate one or
 US 9,046,097 B2
3 4
more embodiments and, together with the description, plary embodiment that a bypass valve 312 is required for
explain these embodiments. In the drawings: directing process fluid flow based on whether the system is
FIG. 1 is a prior art exemplary embodiment depicting a operating as a main test loop or an overall test loop.
centrifugal compressor connected to a gear box and drive Continuing with the exemplary embodiment, the second
motor and configured with the outlet connected to the inlet test loop in the multi-centrifugal compressor test system 300
through a control valve and a process fluid cooler, is the auxiliary test loop and comprises auxiliary centrifugal
FIG. 2 is a prior art exemplary embodiment graph of a compressor 314 connected to an auxiliary gear box 316 and
performance curve of a centrifugal compressor plotted on an auxiliary motor 318. Next in the exemplary embodiment,
head versus flow axis through various resistance loads based the process fluid output from auxiliary compressor 314 is
on the position of the control valve; 10 connected to the process fluid input of auxiliary centrifugal
FIG. 3 is an exemplary embodiment depicting an auxiliary compressor 314 first through an auxiliary valve 326, then
compressor loop and a test compressor loop connected in throughan process fluid auxiliary cooler324, then through an
series and configured to allow performance testing of the test auxiliary control valve 320 and then through an auxiliary
compressor to a Zero head and further to a negative head orifice 328. It should be noted in the exemplary embodiment
condition; 15 that a bypass valve 322 is required for directing process fluid
FIG. 4 is an exemplary embodiment depicting the flow path flow based on whether the system is operating as a main test
of the process fluid in an overall test loop of an auxiliary loop or an overall test loop.
compressor and a test compressor connected in series and Next in the exemplary embodiment, the third test loop in
configured to allow performance testing of the test compres the multi-centrifugal compressor system 300 is the overall
Sor to a Zero head and further to a negative head condition; test loop and comprises connecting the main centrifugal com
FIG. 5 is an exemplary embodiment graph of a perfor pressor 302 and the auxiliary centrifugal compressor 314 in
mance curve of a centrifugal compressor plotted on head series. It should be noted in the exemplary embodiment that
Versus flow axis through various resistance loads based on the the output of the auxiliary centrifugal compressor 314 feeds
position of the control valve through a negative head resis the input of the main centrifugal compressor 302 and the
tance condition based on an auxiliary and test centrifugal 25 output of the main centrifugal compressor 302 feeds the input
compressors connected in series; and of the auxiliary centrifugal compressor 314. Continuing with
FIG. 6 is an exemplary method embodiment flowchart the exemplary embodiment, a connection is made from a
depicting a method for obtaining non-extrapolated empirical branching connection in the auxiliary test loop, between the
data associated with performance characteristics of a com auxiliary centrifugal compressor 314 and the auxiliary valve
pressor at head values lower than the head value losses asso 30 326, to a branching connection in the maintest loop, between
ciated with a test loop connected to the compressor. the control valve 308 and the process fluid cooler 310. Next in
the exemplary embodiment, a connection is made from a
DETAILED DESCRIPTION OF THE branching connection in the main test loop, between the main
EXEMPLARY EMBODIMENTS OF THE centrifugal compressor 302 and the main control valve 308, to
INVENTION 35 a branching connection in the auxiliary test loop, between the
auxiliary valve 326 and the auxiliary cooler 324. It should be
The following description of the exemplary embodiments noted in the exemplary embodiment that other piping
refers to the accompanying drawings. The same reference arrangements are possible and that the branching locations
numbers in different drawings identify the same or similar can be placed in different positions with respect to other
elements. The following detailed description does not limit 40 system components.
the invention. Instead, the scope of the invention is defined by Continuing with the exemplary embodiment, it should be
the appended claims. The following embodiments are dis noted that the multi-centrifugal compressor test system 300
cussed, for simplicity, with regard to the terminology and can be operated as a test system for the auxiliary centrifugal
structure of turbo-machinery including but not limited to compressor 314, a test system for the main centrifugal com
compressors and expanders. 45 pressor 302 and a test system for the main centrifugal com
Reference throughout the specification to “one embodi pressor 302 wherein the auxiliary centrifugal compressor 314
ment” or “an embodiment’ means that a particular feature, and the main centrifugal compressor 302 are operated in
structure, or characteristic described in connection with an series allowing testing of the main centrifugal compressor
embodiment is included in at least one embodiment of the 302 with a Zero or even a negative resistance. Next in the
Subject matter disclosed. Thus, the appearance of the phrases 50 exemplary embodiment, the auxiliary centrifugal compressor
“in one embodiment' or “in an embodiment” in various 314 test loop can be operated by closing auxiliary bypass
places throughout the specification is not necessarily refer valve 322, closing main bypass valve 312 and opening aux
ring to the same embodiment. Further, the particular features, iliary valve 326. In the exemplary embodiment, process fluid
structures or characteristics may be combined in any Suitable flow is controlled by auxiliary control valve 320 and cooled
manner in one or more embodiments. 55 by auxiliary cooler 324. Further in the exemplary embodi
FIG. 3 depicts an exemplary embodiment of a multi-cen ment, the main centrifugal compressor test loop can be oper
trifugal compressor test system 300 comprising three inde ated by closing auxiliary bypass valve 322 and closing main
pendent test loops based on a preconfigured multi-centrifugal bypass valve 312. In the exemplary embodiment, process
compressor test system 300 configuration. The first test loop fluid flow is controlled by main control valve 308 and cooled
in the multi-centrifugal compressor test system is the main 60 by main cooler 310. Continuing with the exemplary embodi
test loop and comprises main centrifugal compressor 302 ment, the overall test loop, i.e., operating the auxiliary cen
connected to a gearbox 304 and a motor 306. Continuing with trifugal compressor and the main centrifugal compressor in
the exemplary embodiment, the process fluid output from series, can be operated by closing auxiliary valve 326 and
main centrifugal compressor 302 is connected to the process main control valve 308 and opening auxiliary bypass valve
fluid input of main centrifugal compressor 302 first through a 65 322 and main bypass valve 312. In the exemplary embodi
control valve 308, then through a process fluid cooler 310 and ment, the process fluid flow is controlled by auxiliary control
then through an orifice 330. It should be noted in the exem valve 320 and cooled by auxiliary cooler 324. It should be
 US 9,046,097 B2
5 6
noted in the exemplary embodiment that the auxiliary cen Next at step 604 of the exemplary method embodiment, a
trifugal compressor is a larger capacity compressor than the control valve is installed in the test loop between the auxiliary
main centrifugal compressor. It should be noted in the exem compressor and the main compressor. Continuing with the
plary embodiment that when operating in the overall test exemplary embodiment, the control valve allows the test loop
loop, the auxiliary centrifugal compressor 314 overcomes the resistance to be changed for different runs of the test loop
losses of the overall test loop and allows the main centrifugal providing the capability to collect data and develop a test
compressor 302 to operate at Vanishing or even negative compressor performance curve. It should be noted in the
heads allowing the performance for the main centrifugal com exemplary embodiment that when the control valve is fully
pressor to be measured directly at these operating conditions. open, the test compressor can be operated, allowing the col
It should further be noted in the exemplary embodiment that 10 lection of performance data, at test compressor heads
auxiliary orifice 328 and/or main orifice 330 are included in approaching Zero or even under a negative condition.
flow path of the overall test loop. Next at step 606 of the exemplary method embodiment, a
FIG. 4 depicts an exemplary embodiment of a process fluid process fluid cooler is installed in the test loop between the
auxiliary compressor and the main compressor. It should be
flow path for an overall test loop 400. Continuing with the 15 noted in the exemplary embodiment that the location of the
exemplary embodiment, a test compressor 402 is connected process fluid cooler can have an optimal installation location,
in series to an auxiliary compressor 412. Next in the exem Such as in the test loop portion flowing from the main com
plary embodiment, the process fluid output from the main pressor to the auxiliary compressor, based on the configura
compressor flows through an auxiliary cooler 420 then tion of the test being performed and the auxiliary compressor
through a control valve 418 before entering as input process and main compressor installed in the test loop.
fluid to auxiliary compressor 412. Continuing with the exem Continuing with step 608 of the exemplary method
plary embodiment, the process fluid output from auxiliary embodiment, sensors are installed in the control loop adjacent
compressor 412 flows through a process fluid cooler 408 and to the process fluid input connection on the main compressor.
an orifice 410 before entering as input to test compressor 402. It should be noted in the exemplary method embodiment, that
It should be noted in the exemplary embodiment that auxil 25 the sensors can, but are not limited to, measuring temperature,
iary compressor 412 is connected to an auxiliary gearbox. 414 pressure, volumetric flow, mass flow, etc. It should further be
and auxiliary motor 416 and test compressor 402 is connected noted in the exemplary method embodiment that the data
to a gear box 404 and a motor 406. It should further be noted collected from these sensors is included in generating a per
in the exemplary embodiment that auxiliary compressor 412 formance curve for the main compressor. Next, at step 610 of
and test compressor 402 can be centrifugal compressors. It 30 the exemplary method embodiment, sensors are installed in
should also be noted that an additional orifice can be config the control loop adjacent to the process fluid output connec
ured in the overall test loop between the auxiliary cooler 420 tion on the main compressor. It should be noted in the exem
and the auxiliary compressor 412. plary method embodiment, that the sensors can, but are not
In FIG. 5, a graph 500 depicts Head versus Flow for a main limited to, measuring temperature, pressure, Volumetric flow,
centrifugal compressor and shows the performance curve 502 35 mass flow, etc. It should further be noted in the exemplary
based on the data collected from an overall test loop proce method embodiment that the data collected from these sen
dure with the auxiliary control valve 418 in the fully open sors is included in generating a performance curve for the
position 504 and the auxiliary centrifugal compressor 412 main compressor.
delivering compressed process fluid flow 506 to the main Continuing at Step 612 of the exemplary embodiment, data
centrifugal compressor 402 inlet and reducing the resistance 40 is collected from the sensors installed in the control loop
to the main centrifugal compressor 402 allowing the collec while the compressors are operating at various resistance
tion of empirical data related to the performance characteris conditions dictated by the position of the control valve. It
tics of the main centrifugal compressor 402 Zero resistance or should be noted in the exemplary embodiment that when the
even negative head operating conditions. It should be noted in control valve is in the fully open position, the main compres
the exemplary embodiment that operation of the multi-cen 45 Sor head at the process fluid input approaches Zero and can
trifugal compressor test system 300, 400 and the data col even reach a negative head value. These circumstances of the
lected and graphed as represented by graph 500 can be used to exemplary method embodiment allow the collection of data
size an electric motor for a centrifugal compressor Such that it for generating a main compressor performance curve without
is the appropriate size based on centrifugal compressor Star having to resort to extrapolation of data in this region impor
tup requirements, i.e., a smaller motor can be specified based 50 tant to startup procedures for a compressor.
on non-extrapolated empirical data from a Zero head, or even The disclosed exemplary embodiments provide a system
a negative head, condition. and a method for reducing the size of a centrifugal compres
FIG. 6 depicts a flowchart 600 of an exemplary method Sor while maintaining the performance characteristic of the
embodiment for obtaining non-extrapolated empirical data larger centrifugal compressor. It should be understood that
associated with the performance characteristics of a compres 55 this description is not intended to limit the invention. On the
sor at head values lower than the head value losses associated contrary, the exemplary embodiments are intended to cover
with a test loop connected to the compressor. First at step 602 alternatives, modifications and equivalents, which are
of the exemplary embodiment, an auxiliary compressor is included in the spirit and scope of the invention as defined by
connected to a main compressor, the test compressor, in a test the appended claims. Further, in the detailed description of
loop. It should be noted in the exemplary method embodi 60 the exemplary embodiments, numerous specific details are
ment that the process fluid output of the auxiliary compressor set forth in order to provide a comprehensive understanding
is connected to the process fluid input of the main compressor of the claimed invention. However, one skilled in the art
and the process fluid output of the main compressor is con would understand that various embodiments may be prac
nected to the process fluid input of the auxiliary compressor. ticed without such specific details.
It should also be noted in the exemplary method embodiment 65 Although the features and elements of the present exem
that the auxiliary compressor has a greater output capacity plary embodiments are described in the embodiments in par
than the main compressor under test. ticular combinations, each feature or element can be used
 US 9,046,097 B2
7 8
alone without the other features and elements of the embodi on non-extrapolated empirical data for the test compressor at
ments or in various combinations with or without other fea head values lower than the head value losses associated with
tures and elements disclosed herein. operating conditions of the overall loop.
This written description uses examples to disclose the 7. The system of claim 1, further comprising connecting a
invention, including the best mode, and also to enable any separate motor and gear box to each of the one or more
person skilled in the art to practice the invention, including compressors and to the test compressor.
making and using any devices or systems and performing any
incorporated methods. The patentable scope of the invention 8. The system of claim 1, further comprising a plurality of
is defined by the claims, and may include other examples that valves configured in the overall loop such that each of the
occur to those skilled in the art. Such other examples are 10 compressors and the test compressor can be isolated and
intended to be within the scope of the claims if they have operated as an independent test loop.
structural elements that do not differ from the literal language 9. A method for obtaining non-extrapolated empirical data
of the claims, or if they include equivalent structural elements associated with performance characteristics of a compressor
to those recited in the literal languages of the claims. at head values lower than head value losses associated with a
Thus, while there has been shown and described and 15 test loop connected to the compressor, the method compris
pointed out fundamental novel features of the invention as ing:
applied to exemplary embodiments thereof, it will be under connecting an auxiliary compressor to a main compressor
stood that various omissions and Substitutions and changes in in a test loop Such that a process fluid output from the
the form and details of the devices illustrated, and in their auxiliary compressor is connected to a process fluid
operation, may be made by those skilled in the art without input of the main compressor and a process fluid output
departing from the spirit of the invention. Moreover, it is from the main compressor is connected to a process fluid
expressly intended that all combinations of those elements input of the auxiliary compressor;
and/or method steps which perform substantially the same
function in Substantially the same way to achieve the same installing a control valve in the test loop between the aux
results are within the scope of the invention. Furthermore, it 25 iliary compressor and the main compressor,
should be recognized that structures and/or elements and/or installing one or more process fluid coolers and one or
method steps shown and/or described in connection with any more orifices in the test loop between the auxiliary com
disclosed form or embodiment of the invention may be incor pressor and the main compressor,
porated in any other disclosed or described or suggested form installing a first plurality of sensors in the test loop adjacent
or embodiment as a general matter of design choice. It is the 30 to the process fluid input of the main compressor,
intention, therefore, to be limited only as indicated by the installing a second plurality of sensors in the test loop
scope of the claims appended hereto. adjacent to the process fluid output of the main compres
What is claimed is:
1. A system for testing a compressor, the system compris Sor, and
ing: 35 collecting data from the first plurality of sensors and the
one or more compressors connected together in series to a second plurality of sensors while operating the test loop
test compressor whereinan output of the test compressor at conditions such that the main compressor head is
is connected to an input of a first compressor in the lower than head value losses associated with the test
series, forming an overall loop; loop.
one or more process fluid coolers in the overall loop: 40 10. The method of claim 9, wherein the main compressor
one or more orifices in the overall loop: and the auxiliary compressor are centrifugal compressors.
a control valve in the overall loop; and 11. The method of claim 9, wherein a cumulative output
a first plurality of sensors configured adjacent to a process capacity is sufficient to overcome head value losses associ
fluid input of the test compressor and a second plurality ated with the test loop.
of sensors configured adjacent to a process fluid output 45
of the test compressor. 12. A method for sizing an electric motor associated with a
2. The system of claim 1, wherein the test compressor is a single or multistage compressor, for optimally meeting the
centrifugal compressor. compressor startup requirements, the method comprising:
3. The system of claim 2, wherein the one or more com obtaining, using the method of claim 9, non-extrapolated
pressors are centrifugal compressors. 50 empirical data for each stage of the compressor,
4. The system of claim 1, wherein the one or more com calculating an overall performance map of the compressor
pressors have a cumulative output capacity greater than the using the non-extrapolated empirical data for each stage
test compressor. of the compressor; and
5. The system of claim 4, wherein the cumulative output calculating the absorbed power of the compressor at startup
capacity is sufficient to overcome head value losses associ 55
using the overall performance map of the compressor to
ated with the overall loop. size the electric motor.
6. The system of claim 5, wherein the testing is associated
with generating a test compressor performance curve based k k k k k