United Stoics
Environmental Pioieclion
Agency
METHANE EMISSIONS 1-TtOM TITH
NATURAL- GAS INDUSTRY
Volume 13: Chemical Injection Tump?
GRI-94 / G?77 3t
EPA 600/R 9
June 1990
Energy Information Administration (U.S. DOE)
National Risk Management
Research Laboratory
Research Triangle Park, NC 27711
fstflt*
Na'.onal Te-Chnica! Inf
-------
YECHNtCAi. HOH5HT DAiA
**-***-"*'"*" !**•'«*•-! IHSjiltilBHStr tailt *£t&3lR'i
'cinert'*iit fB'tiiicftims, itM»:-ii \-}n, v !»i .i .!-.{• joji 7}.
; = irt-,in a! lh«- » u "ior.iti *•- r-.i-i-r I ht n «
^ici'i VAC! ii" -t- 0. 5"r, -•! n-»tur.-,l f- > . i <«.i
!-• tit-o' t) oM»t i-' iy9° Beoulln ftvi.. Wit- pi •<» i -tit '< r Lird ti < '1,1
.- r.i ,is^i<.«p- trom the fuel cjclc fo* n^tnr?«l p, - «nl. n.t c .vi u^itii. lh« ..In1 .1
in,3 pott ifuil.s (tJVi Ps) rc«.enll\ pul liolad I ^ llu Inu i 4"i i rhm<>pta' f-' » ci tu LUJU--
hr.nge (ll'f'C'). Ihu anftly^ij sliowo>i thai naiui ol K^L <'ori''<- U •- i<, poi, i '
global warming than to.il or oil, wlm-ii supports flit tut i o> itciauf >.i ntv.t'\ ^.uL't1'--- - >
by tlielPC'C' and other*. In addition, shn'\ rcbulf.^- ate 1» HIC u ,i >1 \>\ tli, n^tm -1 n -
inilu&try to ruduee opt rating costa whilr j r>ducm,r riinsoioiiu .
K.F Y WORDS AND OOCUMLN1
DESCRIPTORS
Pollution
Emission
Greenhouse Effect
Natural Gas
Gas Pipelines
Methane
Release to Public
U.IDtNriFtcns/OPCN ! ftinpoTgRMj; |c. r.n.sAH ridd/iiiouy
U'lcJar-sified
20 !»tl,t!K!I > CLAii, (1 /',.-., _•'
(HA
2ilJ
I5K
ovc
NO, or P
•12
EPA Porra 2720-1 (9-13)
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FOREWORD
The U.S. Environmental Protection Agency is charged by Congress with pro-
tecting the Nation's land, air, and water resources. Under a mandate of national
environmental laws, the Agency strives to formulate and implement actions lead-
ing to a compatible balance between human activities and the ability of natural
systems to support and nurture life. To meet this mandate, EPA's research
program is providing data and technical support for solving environmental pro-
blems today and building a science knowledge base necessary to manage our eco-
logical resources wisely, understand how pollutants affect our health, and pre-
vent or reduce environmental risks in the future.
The National Risk Management Research Laboratory is the Agency's center for
investigation of technological and management approaches for reducing risks
from threats to human health and the environment. The focus of the Laboratory's
research program is on methods for the prevention and control of pollution to air,
land, water, and subsurface resources; protection of water quality in public water
systems; remediation of contaminated and groundwater; and prevention and
control of indoor air pollution. The goal of thL; research effort is to catalyze
development and implementation of innovative* cost-effective environmental
technologies; develop scientific information needed by EPA to
support regulatory and policy decisions; and provide technical support infor-
mation transfer to ensure effective implementation of environmental regulations
strategies.
This publication Jias been produced as part of the Laboratory's strategic long-
term research plan. It is published made available by BPA's Office of Re-
search and Development to assist the user community and to link researchers
with their clients,
E. Timothy Oppelt, Director
National Risk Management Research Laboratory
EPA
This has peer and administratively reviewed by the U.S. Environmental
Protection Agency, and approved for publication. Mention of or
products does not endorsement or recommendation for use,
This document is to the the National Technical-Information
Service, Springfield, Virginia 22161,
COPYRIGHT
ALL
NATIONAL TECHNICAL
U.S. DEPARTMENT OF COMMERCE
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JEPA-600/R-96-080m
June 1996
METHANE EMISSIONS FROM
THE NATURAL GAS INDUSTRY,
VOLUME 13: CHEMICAL INJECTION PUMPS
FINAL REPORT
Prepared by:
Theresa M. Shires
Radian International LLC
8501 N. Mopac Blvd.
P.O. Box 201088
Austin, TX 78720-1088
DCN: 95-263-081-08
For
GRI Project Manager: Robert A. Lott
GAS RESEARC:T INSTITUTE
Contract No. 50.1-251-2171
8600 West Bryn Mawr Ave.
Chicago, IL 60631
and
EPA T oject Manager: David A. Kirchgessner
U.S. ENVIRONMENTAL PROTECTION AGENCY
Contract No. 68-D1-0031
National Risk Management Research Laboratory
Research Triangle Park, NC 27711
-------
DISCLAIMER
LEGAL NOTICE: This report was prepared by Radian International I i.(.' as mi are.ouni
oi work sponsored by tins Research Institute (OR1) and the U.S. Environmental Protection
Agency (EPA). Neither EPA, Gill, members of Gill, nor any person iKfmu on behalf of
either:
a. Makes any warranty or representation, express or implied, with respect to the
accuracy, completeness, or usefulness of the information contained in this
report, or that the use of any apparatus, method, or process disclosed in this
report may not infringe privately owned rights; or
b. Assumes any liability with respect to the use of, or for damages resulting
from the use of, any information, apparatus, method, or process disclosed in
this report.
NOTE: EPA's Office of Research and Development quality assurance/".quality control
(QA/QC) requirements are applicable to sonic of the count data generated by this project.
Emission data and additional count data are from industry or literature sources, and are not
subject to EPA/ORD's QA/QC policies. In all cases, data and results were reviewed by the
panel of experts listed in Appendix D of Volume 2.
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Title
Contractor
Principal
Investigator
Report Period
Objective
Technical
Perspective
Results
Methane {lie Natural Gas Industry,
Volume 13: Chemical Injection Pumps
Final Report
LLC
GRI Contract Number 5091-251-2171
EPA Contract Number 68-DI-OQ31
Theresa M. Shires
March 1991 - June 1996
Final Report
This report a to quantify the annual methane
from gas-driven injection pumps,
The use of gas has been as a for
the for warming. During
gas less (CO2) per of produced than
either coal or oil. On the of the amount of CO2 emitted, the
for warming could be reduced by gas
for coal or oil. However, since natural is primarily methane, a potent
of gas production, processing,
transmission, and distribution could reduce the of its
lower CO2 emissions.
To investigate this, Gas Research Institute (GRI) and the U.S. Environ-
mental Protection Agency's Office of Research and Development (EPA/-
ORD) cofunded a major study to quantify methane emissions from U.S.
natural gas operations for the 1992 base year. The results of this study
can be used to construct global methane budgets and to determine the
relative impact on global warming of natural gas versus coal and oil,
The 1992 national for chemical injection pumps used
in the production are 1.5 ± 203% Bscf,
on the natural
gas are to be 314 ± 105 Bsef for the 1992
year. This is about 1.4 ± 0,5% of gross natural gas production. The
overall program the of for an
in
-------
increase in gas would be significantly
than the
The program reached its accuracy goal and provides an accurate
of methane emissions that can be used to construct U.S.
inventories analyze fuel switching strategies.
Technical The gas industry has two primary types of chemical injection pumps that
Approach discharge natural gas: piston pumps and diaphragm pumps. Gas-driven
pumps for glycol circulation are presented in a separate study,
An emission rate for chemical injection pumps was determined by
developing an annual emission factor for typical practices and
extrapolating this value based on the total number of chemical injection
pumps (activity factor) to develop a national estimate, where the national
emission rate is the product of the emission factor and activity factor.
Chemical injection pumps are small positive displacement, reciprocating
units designed to inject precise amounts of chemicals into
These pumps are in the production segment to control
problems or protect equiprr^nt. Typical chemicals injected in
an oil or gas field are biocides, demulsifiers, elarifiers, corrosion
inhibitors, scale Inhibitors, hydrate inhibitors, dewaxers, surfactants,
scavengers.
The emission-affecting characteristics of chemical injection pumps
include: frequency of operation, unit size, supply gas pressure, and inlet
methane composition. The frequency of operation was on timed
stroke rates and operator information on the annual use of the devices.
Manufacturer data provided the gas consumption rates per stroke. An
equation relating these parameters wan developed and used to ca''.-ulate
annual methane emissions from a typical chemical injection pump used
in natural as production.
The activity factor development (i.e., the number of chemical injection
pumps nationally) is presented in a separate report. In general though,
the activity factor is based on the number of chemical injection pumps
per active gas well that markets gas. The national methane emission rate
for chemical injection pumps then on the product of the
emission factor and activity factor.
Project For the 1992 base year, the emissions for the
U.S. gas industry is 314 ± 105 (± 33%). This is
equivalent to 1.4% ± 0.5% of gross gas production, from
this program to compare gas from the
IV
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fuel cycle for natural gas, oil, and coal using the global wanning
potentials (GWPs) recently published by the Intergovernmental Panel on
Climate Change (IPCC). The analysis showed thai natural gas
contributes less to potential global warming than coa! or oil, which
supports the fuel switching strategy suggested by IPCC and others.
In addition, results from this study are being used by the natural gas
industry to reduce operating costs while reducing emissions. Some
companies are also participating in the Natural Gas-Star program, a
voluntary program sponsored by EPA's Office of Air and Radiation in
cooperation with the American Gas Association to implement cost-
effective emission reductions and to report reductions to EPA. Since this
program was begun after the 1992 baseline year, any reductions in
methane emissions from this program are not reflected in this study's
total emissions.
Robert A. Lott
Senior Project Manager, Environment and Safety
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TABLE OF CONTENTS
Page
1.0 SUMMARY 1
2.0 INTRODUCTION 2
3.0 GAS-DRIVEN PUMP TYPES 3
3,1 Operation Overview 3
3,2 Emission-Affecting Characteristics 11
4,0 EMISSION FACTOR DATA 12
4.1 Canadian Petroleum Association (CPA) Report , 12
4.2 Methane Composition 12
4.3 Site Data 13
4.4 Industry Boundaries 16
4.5 Manufacturers' Data 18
4.5.1 Diaphragm Pumps 18
4.5.2 Piston Pumps , 21
5.0 EMISSION RATE CALCULATIONS 23
5.1 Diaphragm Pumps 23
5.2 Piston Pumps 24
5.3 National Emission Rate 25
6.0 REFERENCES ..... .26
APPENDIX A - Production Source Sheet A-l
APPENDIX B - Conversion Table B-l
VI
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OF
Page
3-1 Piston Pump Schematic , .... 5
3-2 Piston Pump Cut-away Schematic 6
3-3 Texsteam Piston Pump Schematic ,..,,, ?
3-4 Texsteam Piston Pump Cut-away Schematic ........................... 8
3-5 Diaphragm Pump Schematic 9
3-6 Diaphragm Pump Cut-away .............................. 10
LIST OF TABLES
Page
4-1 CPA of Fuel-Gas Venting Rates for Gas-Operated
Chemical Injection Pumps . .,,,., 13
4-2 Summary of Site Data 15
4-3 Site 16
4-4 Data Set Comparison for Chemical Injection Pumps » , . , . 17
4-5 Pump Manufacturers' Data for Diaphragm Pumps . , 19
4-6 Pump Manufacturers' Data for Piston Pumps 20
VH
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1.0 SUMMARY
This report is one of several volumes that provide background information
supporting the Gas Institute and U.S. Environmental Protection Agency Office of
Research Development (ORJ-EPA/ORD) methane emissions project. The objective of
this comprehensive program is to quantify methane emissions from the gas industry for the
1992 base year to within ± 0,5% of natural gas production starting at the wellhead and
ending immediately of the
This report describes a study to quantify the annual emissions from chemical
injection pumps. Piston and are the most common types of
gas-powered injection pumps in the production An
emission factor for these types of pumps was developed based on site data, manufacturer's
data, and results from a Canadian study. The resulting annual methane emissions from
chemical injection pumps are 1.5 Bscf ± 203%.
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2.0 INTRODUCTION
di'-niiofil injection pumps art," small positive displacement, reciprocating units
designed In inject precise amounts of chemicals inlo process streams, 'these pump;; arc
used in 'ho iijitun-il gas production segment to control processing problems or protect
equipment. Gas-driven chemical injection pumps, which use gas pressure to drive other
fluids, arc commonly used iu production fields when- eluciiie.ity is nut readily m';-ulnblo
The characteristics thai alTeel emissions from chemical injection pumps
include; the si/.e of the unit, frequency of operation, supply ;.ias pressure, and mlei mothcine
i'oitipysiiton tmissiofi factors for diaphragm and piston pumps were determined by
converting a manufacturer's reported gas consumption per volume oi' dj«ni«il pumped u>
gas emitted per stroke, based on the plunger diameter and stroke length of typical pumps.
The frequency of operation was based on timed stroke rates from site visit; and operator
information on the animal use of the devices. An eijtrdthm refmtCL- ihovr puamdt-ix \va>.
developed for each tvpe of chemical injection pump (piston pumps and diaphragm pumps}.
The number of gas-operated pumps in the U.S. production segment was determined by
establishing a ratio of pumps to wells that market natural gas. Annual methane emissions
from chemical injection pumps were calculated baswl on tin- piwHet of the emission taetor
for a typical pump and the activity factor (count of chemical injection pumps; nationally).
This report presents an estimate oi loial I! S. emissions from f icse pumps.
'Hie following sections quantify the amount of methane thai is released from chemical
injection pumps nationwide. A description of ehcmk..il injection pumps typieatly used in
the natural gas industry is provided in Section 3. Section 4 describes the sources of
information used to determine methane emission factors for these pumpK National inmuai
emissions are calculated in Section 5.
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3.0 CAS-DRIVEN
This section describes chemical injection pumps found in the natural gas
industry, as well as differences in installations in various segments of the industry,
3.1 Opera tion Overylew
All industrial pumps two a driver and a motive
side. The driver provides the energy for the pumping operation; the motive delivers
the energy to the fluid being moved. For a typical industrial centrifugal pump, the driver
might be an electric motor; the motive is an and
In the natural gas industry, gas-driven pumps are small pumps used in the
production field where electricity is not readily available. These pumps use gas pressure to
drive other fluids. The supply gas can be air (as in gas plants), but
most often it is natural gas directly from the stream. The majority of
gas-driven pumps in the field have one of two purposes: glycol circulation (see Volume 15
on gas-assisted glycol pumps') or chemical injection,
Chemical injection is needed in the field to add small amounts of chemicals
that control processing problems and protect the equipment. Typical chemicals injected in
an oil or gas field are biocidcs, inhibitors,
hydrate inhibitors, paraffin and
(H2S) scavengers. These chemicals are normally injected at the wellhead and into gathering
lines or at production separation facilities. Since the injection are typically small, the
pumps are also small. They are to the being
injected.
Chemical injection pumps are reciprocating units
designed to inject precise amounts of a Positive
-------
pumps work by allowing a fluid to flow into an enclosed cavity from a low-pressure
source, trapping the fluid, and then forcing it out into a high-pressure receiver by
decreasing the volume of the cavity. A complete reciprocating -stroke two
movements, referred to as an upward motion or suction stroke, and a downward motion or
power stroke. During the suction stroke, the chemical is lifted through the suction check
valve into the fluid cylinder. The suction check valve is forced open by the suction lift
produced by the plunger and the head of the liquid being pumped. Simultaneously, the
discharge check valve remains 'closed, thus allowing the chemical to in the fluid
chamber. During the power stroke, the plunger assembly is Forced downwards,
immediately shutting off the suction check valve. Simultaneously, the chemical is
displaced, forcing open the discharge check valve and allowing the fluid to be discharged.
This complete movement represents one full stroke.
The two types of gas-driven pumps commonly used in the natural gas
industry are the piston pump and the diaphragm pump. These pumps operate in the same
mariner, but with different reciprocating mechanisms. The barrel-type pump,
illustrated in Figures 3-1 and 3-2, consists of a cylindrical piston-plunger assembly.2
Movement of the larger-diameter piston provides the force to move the plunger,
Another type of piston pump observed at. sites in California (Figures 3-3 and 3-4) uses a
horizontal plunger to operate a gear mechanism that drives the plunger,3 The diaphragm
pump, illustrated in Figures 3-5 and 3-6, uses a flexible diaphragm to move the plunger.4'5
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3-1. Kston Pump Schematic
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GAS
OUT
FLUID
SUCTION
Figure 3-2. Piston Pump Cut-away Schematic
-------
OS
e
4J
«B
U
on
a
E
a
a,
s
4)
L,
M
E
-------
LU
f
6,
I
S3
B.
s
es
!.
8-
*
te
8
p =
-------
O
t/5
a.
6
s
S
or-
es
L*
JS
s,
&£•
-------
o
IAS
CAR SIDE)
GAS
EXHAUST
FLUID
DISCHARGE
3-6, Pump Cut-away
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3-2 Emission-Affecting. Characteristics
the gas-driven in
chemical injection service include;
» Frequency of operation (pumping rate);
» of the (volume of the motive chamber);
• Supply gas pressure (which affects density); and
* Inlet methane composition.
For this study, the frequency of by the
stroke intervals and collecting information about pump operating schedules. Determination
of the unit size was based on manufacturers' data for the types of pumps observed during
site visits. Supply gas pressure, which affects the density of the gas, noted during site
of an gas on literature
data. These are in in to their on the
emission calculations in the following section.
n
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4.0 FACTOR DATA
Four of information to from
chemical injection pumps: results of a study performed by the Canadian Petroleum
Association, literature data for methane composition, data collected from site visits, and
pump manufacturers* data.
4,1 Canadian PetroleumAssociation CCPA) Report
The Canadian Petroleum Association (CPA) conducted a study to quantify
oil and gas in Alberta,6 from
diaphragm chemical injection pumps were determined from bagging tests of five pumps. The
measurements were very consistent, ranging from 254 to 499 scfd/pump (see Table 4-1).
The average natural gas emission factor from the Canadian study was 334 ± 30%
sefd/pump,
4.2 Methane Composition
Emission factors for methane are calculated from the rate of natural gas
by the composition. The of in
natural gas to be 78.8% ±5%. this value are available in
Volume 6 on and sources.7
12
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5- OF -FUEL-GAS FOR"''
^,; ' = ">:-lr.X-,: r';-~ r -~\ -CAS^PERATED" CHEMICAL-INJECTION PUMPS' V-';-' / " -'
r~-~.- i~;,'-'_ •-"--.:"* "-:_• St%\ ,,-,'^ " "-;••*.' Quantity' - '----_.' - ' ---O, \/ _, •-" -^ .-'"-„
--, v ; '-"-'"-„ /,>,", \Type'of -r^Tjipfc of. .-" .Type,.of--."_ Measured - Min.Flow:^ Max, Flow ," -'-_ ^Avg^.Flow; .
•r^~ J"s'7*;?",: "-v , '-^n'st -^-J¥aclI%rf:"Ea»ipnient --' if Qnce\ [._ Rate/Puni|t - v,^Kaife/Piimp *",/ ,'Rate/iPiiinp,
Oi!,Battery' Line.Heater "' -l.,~ - - 0\- -" °0 -, , 498.9 scfd -_-
_i; '•S"icJ;7:'- CIP ":V 'oil Battery; Line- '"' 1 / ' 165.8 scfd ' "'-; .=349:6 scfd",, .-."- .-.--254.4'scfd
;> '' \ "—-•-''; JCIP/ -OiLBsttery Sales~L*ine ;' -1 / - ^ "0 -- -- ' ->1917 scfd - _ 3'73.7 scfd "
- •--''; ~~_-~'„"" ,GD>' " l^Mitttfr Oil Wellhead" - - 1 r.' " ' b - ' ' --" b- _ '-,: _--254.3 scffl ---
* '.' ""•"""- „ " -.' . "-FttW-- .-"-"-_/"'/"•'-- " " -- '' --'-"" ''."'"
^". CIP - Minor Oil "-Wellhead' - , II- " b -' . - _ , b- 290.3 scfd /
:./ ,{r"--_-,* ^ 'Retf ;/; -:'"_ -.•.'-."-. . ' -;'.-'" ----..%-' ' ' ..:-••
",-",--:-:-" '-.;.' ;--. ". \ - ",-: ' •', AVERAGE"- '-' - ,* ':' -~' 334scfa±3o%
, * CIP *= Chemical Injectio
" \ b Minimum and ntaximun) flow rates were jiot measured in these cases, only the average rate. _"."
;4.3-:-'-^, SitePata " ' "-'-•• . ' ' r " '•.-.: ' - '~ '
V ' -" , _ , Chara.K ,-" »ics that allow populations and average pump cmissioa factors to be
I ^estimated were gathered from 19 sites by telephone contacts or,site visits. .The.information -
- collectedJncluded: ,^
.Total number of chemical injection pumps fora particular site; - . - .
Number, of chemicaljnjection pumps used in natural gas production ' -1
(see Volume 5 on activity factors*-for more infoimation on the industry
boundary definition); - - - .-, ~ , • . i
Energy source (gas,-air," or electric);
Frequency of=operation (pumping rate in strokes/tnin); * .
Number of puinps active or idle; = _-,";•_
-Pump operation schedule; -_'_.' -. - ,
Size of the unit (volume displacement of the motive chamber);
13
^-~' P r ,,,~-_'"^ f'-
*~ ?V*.C "-"•'
-------
• Maimfaeuirer and mode! immher of the unit; and
• Supply gas pressure,
Table 4-2 lists the site mform?.uo» and Table 4-3 summarizes the sir;: data by pump rype.
This information was used to produce an estimate of equipment populations
characteristics for the U.S. population of gas-driven ehcmk'al injection pumps.
The frequency of operation, or pinupUig rate (Mruke/min). WHS based oil limed
stroke intervals measured during site visits The number of rate samples is shown in Table
4-2 for siies where this parameter was measured. For silc.s with no rale sample
measurements, calculation of zm average value lor the pump type (either pjston or dia-
phragm) on measurements from other sites,
The fraction of eaeli pump type, piston versus diaphragm, was calculated
on the total T>umber of each type of p'_7iip observed. Table 4-2 shows that piston an<1
pumps are equally distributed for the visited (49 8/1 piston pomps compared
with 50.2% diaphragm pumps).
Some of the pumps are only opemred on a seasonal ha.^is. Therefore, opera.o1'
information and observations from site visits were used to determine the fraction of lime the
pump operated annually. Table 4-3 shows that piston pumps operate approximately 45 A of
the year, while diaphragm pumps are in use 40% of the year.
At four of the sites visited, both piston and diaphragm pumps were observed.
However, no estimate of the relative number of each type of pump was made; only {he total
number of chemical injection pumps was provided. For these sites, the fraction of piston
versus diaphragm pumps observed from the other sites were applied so that the pump
operating data collected at the four sites could he used.
14
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TABLE 4-2. SUMMARY OF SITE DATA
Site
i
~i
t+
3
4
5
6
7
8
9
10
II
12
13
14
IS
16
I?
IS
19
Pump Type
Piston
Piston
Piston
Piston
Diaphragm
Diaphragm
Diaphragm
Diaphragm
Piston
Diaphragm
Piston
Diaphragm
Diaphragm
Diaphragm
Diaphragm
Piston
Diaphragm
Piston
Piston
Piston
Piston
Piston
Piston
Power
Media
Nat, Gas
Nat. Gas
Nat. Gas
Nat. Gas
Nat. Gas
Nat. Gas
Nat, Gas
Nat. Gas
Nat. Gas
Nat. Gas
Nat. Gas
Nat. Gas
Nat. Gas
Nat. Gas
Nat. Gas
Nat. Gas
Mat. Gas
Electric
Eiectric
Nat. Gas
Air
Air
Nat Gas
Total
Number of
CIPs at the Site
108
5
203
666
5
28
273
60
36
4
12
8
25
115
24
1
4
5
I
CIPs Within Gas
Industry Boundaries
at (he Site
to
5
0
0
5
28
273
0
36
0
12
8
25
§
0
0
0
0
]
Number
of Rate
Camples
14
0
8
0
0
1
I
1
0
0
1
2
3
0
0
0
0
-
-
1
4
3
1
Strokes/ ' %
win Gperiiling
6.64 63.6
93
16.8 61,9
27.3
27.3
2 90
12 25
30 50
3.8
3.8
0.5 100
15 100
9,2 81.3
100
50
100
100
--
-
0.33
55
65
40
Number
Operating
68.7
4.6
125.7
9ft. *,
91.1
4.5
6.9
136.4
1.2
1.2
17.9
18.1
3.3
12.0
4.0
12.5
12.5
-
--
--
--
--
--
15
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TABLE 4-3. DATA
Pislon Pumps
Total Number of Gas Operated CIPs
Observed from Site Visits
% by Type
% Operating
Average Strokes/min
49
44
26
327
,8 ± 38%
.6 ± 62%
.3 ± 29%
Diaphragm Pumps
50.2
40.0
13,6
329
± 38%
i- 52%
+ 49%
4.4 Industry Boundaries
The "gas industry" boundaries include ail gas well but excludes
equipment with oil production. This boundary definition is significant for
chemical injection a of are specifically for
chemical addition to oil wells.
During site visits, data were collected for all pneumatic chemical injection
pumps regardless of the associated equipment. As shown in Tables 4-2 and 4-3, data
collected for the purpose of this characterization report consist of actuation measurements
pump make/model types for pneumatic chemical injection pumps, including pumps
r;-~-_;-,Tted liy air and to the oil industry. The decision to
include all for the factor but to account for the industry boundary
definition in the activity factor. (That is, the activity factor only includes natural gas
powered chemical injection pumps associated with the natural gas industry.)
To examine the effect of this decision, emission estimates were determined
two sets: one containing all of the available data, the other using only data
for gas-operated chemical injection within the natural gas industry. The res-'ts of this
are in Table 4-4,
16
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TABLE 4-4. DATA SET COMPARISON FOR CHEMICAL INJECTION PUMPS
Using AH Data
Percent of Total Pumps, %
Pump Actuation Rate, strokes/mill
Number of measurements
Number of sites
Piston
49.8 i 38%
26.32 ± 29%
32
7
Diaphragm
50.2 ± 38%
13. M ± 49%
8
5
Using Only Natural Gas
Industry Data
Piston
4.5 ± 6?S%
3.57 i: 42%
15
2
Dixpliragm
95.5 ± 32%
14.75 ±
61%
5
4
Operating Fraction, %
Number of sites
Methane Emissions Factor,'
scfd/pump
44,6 ± 62% 40,0 ± 52%
? 10
248 ± 83%
77.5 ± 148% 58.0 ± 39%
4 6
668 ± 88%
"Details on the emission factor calculation arc presented in Section 5.
Limiting the to strictly gas-operated within the natural gas industry
significantly reduces the database from which the emission factors are calculated and results
in a much larger emission factor. A follow-up conversation with a manufacturer of both
of that the are on the of
required and the injection pressure, the type of production gas or crude) is not a
leading factor for selecting the pump type. Both pump types can accommodate conditions
associated with either natural gas production or crude production. This was confirmed by
industry contacts as well. Therefore, because a definitive reason for choosing one pump type
for gas production not be the set—using all of the
data—was used to determine the emission factor per pump. The actual number of pumps
operating on gas within the natural gas industry boundaries is accounted for in the activity
factor.
17
-------
4.5 Manufacturers'.Data
Stroke frequency (strokes per minute) was determined from site daia; however
chemical injection gas to the volume of chemical
(scf/gal). To convert scf/gal to scf/strokc, the volume of chemical displaced per stroke was
calculated based on manufacturers' data for stroke length and plunger diameter (for
diaphragm pumps) or piston diameter (for piston pumps) as «;}i0wn.2'M*19'RU1
Gas Usage, scf _ Strokg_Length (in.) » Diameter (in.)- _ gal. „ ,, t ( set \ /|\
stroke stroke 4 231 iu,J
Tables 4-5 and 4-6 the information provided by the diaphragm and piston pump
respectively. The gas per is also for
pump size,
4,5.1 Diaphragm Pumps
The diaphragm pump provided gas in of standard
cubic feet of gas (at 1 aim and 60°F) required to pump one gallon of liquid, where gas usage
for each pump varies slightly with discharge pressure. Despite the wide range of pump sizes
available, the to an rate per
(with a 90% vonfidenee interval of ± 10%) for the pumps shown in Table 4-5, The
pump manufacturer were examined over the pressure of 0 psig to 1000
psig {discharge pressure ranged from 20 to 1060 psig for sites visited), for which the gas
usage varied by only 20%. For example, the gas usage for the 3/8-inch Western Chemical
105 to 118 over the of 0 to 1000 psig.*
Calculation of the per on the and
stroke as shown by Equation 1. Combining the calculated liquid displacement for
each plunger size over the range of gas usage values, results in a matrix of calculated
sef/stroke values. Table 4-5 shows values which vary from 0.0451 to 0,1660
18
-------
TABLE 4-5. PUMP MANUFACTURERS' DATA FOR DIAPHRAGM PUMPS
Manufacturer/
Model
Western Chemical
Pumps, Inc. ''
Texsteam Series
5000 4
Texsteam Series
5100s
CPA
Diaphragm Pumps
Plunger
Diameter, Stroke
in. Length, in.
3/8 7/8
5/8 7/8
1/4 i/2 1 1/4
3/8
1/2
3/4
t
f 1/4
1/8 1/3 - 1
1/4
3/8
1/2
ft
Diaphragm Pump Average
Natural
Gas Usage,
scf/gal"
105-118
42-5?
280 - 756
140 - 3(,g
80.6 - 212
36 - 117
20.6 - 62
13.6 - 44
457 - 1407
244 - 810
120 •• 492
53 - 186
Calculated
Natural Gas Usage
scf'/stroke8
0 047-U.O:> 1
0.054 0.073
Average — 0.0563
0.0744 - 0.0813
0 0837 - Q.WI4
0.0853 - 0.0978
0.0851 0.1329
0.0860 0.1360
0.0866-0.1660
Avcn,ge =-= 0 ()%?
0.0546- 0.0561
0.0519-0.0574
0.0574 - 0.0784
0.0451 - 0.0527
Average - 0.0567
Average - 0.01701'
0.0719 ± 10%
To convert from sef of natural gas to scf of methane, multiply by inol % methane in
natural gas.
* The Canadian emissions, reported in Table 44 as scfd/punip. where converted to sef/strokc
based on (lie diaphragm pump actuation rale determined from site daU* and shown in
Table 4-3.
-------
TABLE 4-6. PUMP MANUFACTURERS' DATA FOR PISTON PUMPS
Piston Pumps
Manufacturer/
Model
Line Mfg.2
Piston
Diameter, in.
2 1/2
Stroke
Length* in.
1/4
I
Calculated
Natural Gas Usage
scf/stroke8
0,0022
0.0086
Arrow Specialty Co.
Williams Chemical
Instruments "
Texsteam 3703 J
Piston Pump
J 1/4
1 1/4
2 1/4
2 1/4
„
Average
1/8
W
1/8
i
„
0.0003
O.OOli
0.0009
0.0070
0.0013b
± 65%
Conversion of act" to scf is based on a typical supply gas pressure of 30 psig determined
from reference material12 as well as pressures observed at eight sites.
1 The piston size and stroke length were not specified for this type of device. Instead, the
manufacturer provided the gas usage per gallon of chemical pumped, which ranged from
160 to 500 scf/gallon for discharge pressures of 0 to 1000 psig. Based on the average
stroke frequency observed at Sites 17 and 18. the corresponding gas usage per stroke
from 0.00063 to 0.00195, with an average value of 0.0013 scf/stroke.
20
-------
scf/stroke. Calculating the average of the range of manufacturer data and the Canadian
measurements results in the average gas emission of 0,0719 scf/slrokc ± 10% for the
diaphragm pumps.
4.5.2 Piston Pumps
Manufacturer for the Texsieam piston pump were similar to that provided
for the pumps; standard cubic feet of gas required to pump one gallon of liquid.
In addition, the manufacturer provided ranges for the volume of chemical pumped (gal/day),
corresponding to different actuation rates (stroke/min). Actuation measurements from the
two sites where the Texsteam pumps were observed were used to convert the gas discharge
rate per volume of chemical to the discharge rate per stroke as shown in the following
equation:
Gas Usage, scf _ scf gal. day r
—~_—. ~,— _ x ~ - x — V
Stroke gal. day strokes
For the barrel type piston pumps, the gas usage was calculated based oil the
manufacturer specifications for the piston diameter and stroke length:
Gas Usage, acf _ Stroke Length (in.) _ H Diameter (in..)2 . tf n\
stroke stroke 4 1728 in,3
Piston pumps are not as diverse as diaphragm pumps and have a limited number of piston
sizes. Based on the use of these pumps in the natural gas industry, the 114-inch to 2'/2-inch
piston diameters would be typical.
The stroke length is adjustable for the piston-type pumps. Since specifics
concerning the typical for pumps at each site were not known, die range of
manufacturers* values (1/8 to 1-inch) were used. In addition, the supply gas pressure can
affect the gas usage for these pumps due to the effect of pressure on gas density. Based on
-------
manufacturers' data, piston pumps are designed for supply gas pressures ranging from 15 to
85 psig, A supply gas pressure of 30 psig was used for the emission calculations based on
an of and reference material,'2 Combining the data from the four
manufacturers, the average gas usage for the piston pumps was determined to be 0.0037
scf/stroke ±65% (Table 4-6)-
-------
5,0 SATE CALCULATIONS
Sile information was used to determine the average actuation rate
(strokes/min}, the fraction of each type of pump (piston versus diaphragm), and the
percentage of operating time for each type of purnp. The manufacturers' data were used to
determine the volume of gas per stroke (scf of gas/stroke). Radian combined
the site information and manufacturers' data, as in this section, to calculate
emissions for each type of pump in standard ethic per day per pump. An
average pump emission factor was calculated by combining the emission factors (EF) for
diaphragm and piston pumps:
pump •"" piaeB pumps * *1*'pkifln pumps ~*~ "ac"*'%iajjl!tsfm pumps ^ *-*" diaphragm pninp
x 50 scfd methane/pump)^ +
(50,2% x 446 scfd methane/pump)djaphragni
248 scfd methane/pump
where, the fraction of each type is from Table 4-3, Details the data values,
calculations, and the national are in this
section -
5.1 Diaphragm .Pumps
Calculation of the emission factor for the diapliragm pumps was based on the
fol lowing equation:
&s Usage (scf/slrokc) x Frequency (strokes/day) x Operating
tLne x % Methane (5)
23
-------
where;
Gas usage = calculated gas from Equation 1 (0.0719 ± 10%
scf/stroke).
Frequency = per day of the pump (19,642 + 49%
stroke/day).
Operating time = portion of the year that the pump is operating (0.40 ± 52%).
% Methane = 78.8 mol % ± 5% for the production segment.
The total methane emission factor for diaphragm pumps is 446 scfd/pump ±77%.
5,2 Piston. Pumps
Caiciiiation of the factor for on the following
equation:
— Gas usage (acf/ stroke) x Density (scf/acf) x Frequency
(strokes/day) x Operating time x % methane (6)
where;
Gas Usage = Calculated gas from Equation 3 (in actual ft'/stroke).
Density — scf/aef at supply gas pressure (average 30 psig)
(combined average value of volume and density is 0.0037 ±
65% scf/stroke).
Frequency = per day of the average pump (37,901 ±29%
strokes/day).
Operating = of the year that the pump is (0.446 ± 62%).
% = 78.8 mol % ±5% for the production segment.
The resulting methane emission factor for piston pumps is 48.9 scfd/pump + 106%.
Using Equation 4, the diaphragm pump and piston pump emission factors are
expressed in a ratio based on the fraction of each type of pump observed from site visits
(0.498 ±38% piston pumps and 0,502 ±38% diaphragm pumps from Table 4-3) to
produce an emission factor for a typical chemical injection pump of 248 ±83% scfd/pump,
24
-------
5,3 National Emission Kate
The is calculated using the emission factor per average
pump (248 scfd/pump from Equation 4) multiplied by the number of pumps used in
production fields nationwide. The number of gas-operated pumps in the gas industry
production segment was determined by establishing the ratio of the number of pumps to
active that market gas. Details on this calculation are provided in Volume 5 on activity
factors,* The resulting activity factor is a of 16,971 ± 143% in the
production sector,
Multiplying the chemical injection pump emission factor by the activity factor
yields the total annual emissions for gas-operated chemical injection pumps:
ER^p = 248 - y 365 x 16^71 ±m% pumps
pump year
The resulting emissions for the production segment are 1.5 Bscf + 203%,
25
-------
6.0 REFERENCES
1. Myers, D.B., and M.R. Harrison. Methane Emissions from
-------
APPENDIX A
Production Source Sheet
A-l
-------
PRODUCTION SOURCE SHEET
SOURCES: Wells, Gathering Facilitii*
COMPONENTS: Chemical In)ection Pumps
OPERATING JVIOtM'l: Normal Operation
EMISSION TYPE: Unsteady, Vcnlcd
ANNUAL EMISSIONS: 1.5 Bscf + 203%
BACKGROUND:
Cias-driven cliemical injection pumps use gas pressure acting on a piston Ui pump a dicmioi! im the apposite
side of the piston. The gas is then vented directly to The atmosphere. The pumps are used lit add f.hermetf»,
such as corrosion inhibitors, scale inhibitors, triocidc, deiiiulsiiier. dariffer, and hydrate inhibitors to operating
et)uip!iieoi. Two types of were observed: I) piston pumps, and 2) diaphragm pinups. Some of flu:
pumps observed wen- inactive al (lit: time or had seasonal operation.
EMISSION FACTOR: 24fi scftl/average pump ± 83 %
(This was adjusted tor the production methane content in natural gas al 78.8 UM>|%.)
This average emission factor is based npon the following equation:
EF^ „,,,, = Fr,m x EF;,«,, •}• F,,,,,,^,, x EFltaph,,K1,,
where:
Fpjs^.. — fraction of the pump population that is the piston iype- = 4V.8'* + 38%
EFp,,,,, = emk's'oti factor of an average piston pump — 48,9 sci'd/pump i- 106%
Piimiirjwis = fraclioTi of the pump population thai is the diaphragm type — 50,2% ± 38%
£?<»»*.!.,,•» = emission factor of an average diaphragm pump = '146 scW/piimp ± 77%
The average device emission factor was determined by an aggregation of device emissions calculated for
multiple U.S. sites. For piswn pumps, the emission factor was determined by ihc following equation.
EFpBM1 = Gas usage (aef/slroke) X Density (sef/acf) X Frequency (strokes/day) >;
Operating lime x % methane.
where:
Gas usajje = calculated gas usage based on piston dinmeiet anil stroke IfHi'.lh (in u^tuul
ft3}:
Densiiy = scf/aef at supply gas pressure (average 30 psig) (combined average v.iiw. oi
volume and density is 0.0037 J, 65% scf/stioke),
Frequency = strokes per diiy of the average, pump (37,901 j_ 2fJ% sirokcs/day),
Operating time = poninn of time thai the pump is operating (0 -'Wd -\ 67%); ami
% methane = 78.8nioi?>- + 5?v for the productiuti scgnieut.
Based on siie and manufacturer data, the resulting national pLtOn pump emission factor IK 4S *J scltj/pmnp -i
106%.
-------
For diaphragm chemical injection pumps, the emission factor was determined by the following equation:
win. e:
ophntnt ~ Gas usage (scf/gal) x Volume (gal/stroke) x Frequency (strokes/day) x
Operating time x % methane
Gas usage = volume of gas (in standard ft3) required to pump one gallon of liquid chemical
(provided by the manufacturer);
Volume = liquid displaced per stroke based on the plunger diameter and stroke length
{combined average value of gas consumption and volume is 0.0719 ± 109,
scf/stroke);
Frequency = strokes per day of (he average pump (19,642 ±49% strokes/day);
Operating lime = portion of lime that the pump is operating (0,40 ± 52%); and
% = 78.8 ntol% ±5% for the production segment,
Using the site, manufacturer, and measured data to calculate the emission factor equation terms, the total
diaphragm pump emission factor was determined to be 446 scfd/pump ±77%.
Stroke volume was calculated from pump manufacturers' data and site observations of manufacturer and model
number. Density was calculated based upon observed site supply gas pressure, and frequency was based upon
timed stroke intervals observed while on site. Operating time was estimated by site personnel (if seasonal), or
was the percent of at the site that were during the visit. The emission factors
shown above (in scfd/pump^ have been corrected for the natural gas composition in the production segment of
78.8 mo! % methane.
EF DATA
3,
4.
5.
6.
The report entitled Methane Emissions from the Natural Gas Industry, Volume 13:
Chemical Injection Pumps (1) establishes the important emission-affecting
characteristics.
Site visit data and reference material established the density from supply gas pressure
at 30 psig.
For the piston pumps, the stroke volume was estifliated from manufacturers* data of
pumps found at each site.
Manufacturers* for the diaphragm provided scf of gas required lo pump
one gallon of chemical. This information was with the calculated liquid
displaced for a range of pumps to give an average volume.
The frequency of per day was determined from 40 timing
taken at 12 sites. The operating time was determined from data at 13 sites.
Measurements of 5 diaphragm chemical injection pumps were provided from an
emissions estimate program by She Canadian Petroleum Association,
EF ACCURACY:
Basis:
1.
2.
3.
Operating lime confidence bounds (at 90% confidence) were calculated by analysis of
the spread of ? sites for piston pumps and 10 sites for diaphragm pumps.
Actuation confidence bounds (at 90% confidence) were based on measurements from
7 sites for the piston pomps and 5 sites for the diaphragm pumps,
It was that the manufacturers' data are completely accurate. Data for the
piston pumps were on information from 4 manufacturers, Diaphragm pomp
data were provided by 2 manufacturers.
A-3
-------
4.
90% confidi«,€e bou,"ds for each value were carried through error propagation to
result in (lie t.nal 90% confidence bound,
ACTIVITY FACTOR: I6,«>71 pumps in (he production segment + 143 %
The number of gas actuated pumps used in the production segment was determined by establishing the ratio of
the number of to active wells (oil or gas) that market Si»e data wen: organized inio regions and
regional values were determined. The regional ratios were then multiplied by the regional count of active wells
that market gas in that region to the count of injection in the region. Finally,
regions were added together to determine the national number. The activity factor is then:
(1)
National AF =
n
E
(Regional AF)
where n = lota! number of regions
(2)
Regional AF = (R,'s) x (W)
where Rj = ratio of tola! pumps to total wells in Region j
where W = number of wells in the region
AF DATA
2.
3.
The active oil and gas weils are from A.G.A. Gas Facts (2). The active oi! wells that
market gas are determined by multiplying the total national active oil wells times the
fraction that market gas. The fraction is determined from a Texas Railroad
Commission iease study that shows the percent of oil leases that market the associated
gas in Texas (3).
The pump counts were obtained during the site visits. Inactive, electrically driveri, j)r
air driven pumps were not counted.
Regional extrapolation by gas well count was used.
AP ACCURACY:
Basis:
1.
2.
The accuracy for the active gas weils is assigned by engineering judgement, based
upon the fact that the number of active wells is tracked nationally and known
by A.G.A./DOE, etc.
The accuracy for the national AF is error propagation from the production
sites visited.
ANNUAL EMISSIONS: 1.5 Bscf ± 203 %
The national annual emissions were determined by multiplying an emission factor for a typical pump by the
popt lation of chemical injection pumps in the production segment.
REH5HENCES
1. Shires, T,M, Methane Emissions from the Natural Gas Industry. Volume 13: Chemical Injection
Pump, Report, GRI-94/0257.30aiid EPA-600/R-96-080m, Gas Institute and U.S.
Environmental Protection Agency, June 1996.
A-4
-------
2. American Gas Association. Gas Facts: 1993 Data, Arlington, VA, 1994.
3, Texas Railroad Commission, P-l, P-2 Tapes, Radian flies, Austin, TX, 1989,
A-5
-------
1
Conversion Table
B-l
-------
Unit Conversion Table
English to Metric Conversions
I scf methane
3 Bscf methane
1 Bscf methane
1 Bscf
1 short ton (ton)
1 Ib
1 ft3
1 ft3
1 gallon
] barrel (bbl)
1 inch
! ft
1
1 hp
1 hp-hr
1 Btu
1
1
T(T)
1 psi
19,23 g
0.01923 Tg methane
19,230 metric tonnes methane
28.32 million cubic
kg
kg
m3
28,32 liters
3.785 liters
158.97 liters
cm
m
km
0,7457 kW
0,7457 kW-hr
1055 joules
293
430 g/GJ
1.8 T f C) + 32
51,71 mm Hg
Global Wanning Conversions
Calculating carbon equivalents of any gas:
= of gas) x
MWi
\ MW, gas
x (GWP)
B-2
-------
Calculating CO2 equivalents for methane:
cev,
of CO2 equiv. = CH4) x j | x
, CH,,
where MW (molecular weight) of CO2 = 44, MW carbon = 12, and MW CH4= 16.
Notts
scf
Bscf
MMscf
Mscf
Tg
Giga (G)
Metric tonnes
psig
psla
GWP
MMT
MMTCE
of CO2 eq.
Standard cubic feet. Standard conditions are at 14,73 psia and 60°F.
Billion cubic feef (10* scf).
Million cubic feet.
Thousand standard cubic feet.
Teragram {1012 g).
as (10*).
1000 kg.
Gauge pressure.
Absolute pressure (note = + atmospheric pressure).
Global Wanning Potential of a particular gas for a given
time period.
Million metric of a gas,
Million metric tonnes, carbon equivalent.
Million metric tonnes, carbon dioxide equivalent.
B-3
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