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R e c o v e r
R e u s e
R e d u c e
John Zink Company, LLC
Flare Gas Recovery Systems
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JohnZinkCompany
John Zink Company has long been recognized as the world leader in the design
and manufacture of industrial flares and related equipment. John Zink also has
been an industry leader in the design and supply of packaged vapor recovery
systems. This experience led Zinks engineers to develop and of fer systems to
recover VALUABLE flare gases, compressing them back into the plant for use as
feedstock, fuel or product. This technology also reduces plant emissions of
combustion by-products such as NOx, CO, and CO2.
WhyFlareGasRecovery?
John Zink Company, LLC
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Why Flare Gas Recovery?
FLAME LENGTH (FEET)
HEAT
RELEASE
(M
ILLION
BTU/HR)
Annua
lVa
lue
o
f
Fue
lRecovere
d*
250 $4,380,000
20 0
15 0
10 0
50
$3,504,000
$2,628,000
$1,752,000
$867,000
5 10 15 20 25 30 35 400
FLAR
ETI
PDIAM
ETE
R
30
INCH
2 4I NCH
1 8I N
CH
1 4I NC
H
1 0 I NCH
The chart above shows the estimated heat
release associated with elevated flares based
on the flame height. The heat release can
then be correlated to a potential annual
savings resulting from flare gas recovery
by using the axis on the right.
* Based on $2/Million BtuFLARE GAS RECOVERY ECONOMICS
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John Zink Flare Gas Recovery Units (FGRUs) provide many
benefits to the end user including:
Conservation of otherwise wasted hydrocarbons can
dramatically reduce fuel gas costs. In one case a unit
costing $1,300,000 paid for itself within the first year of
operation. The end user credits the system with recovering
over $30,000 ,000 in gas since installation. This same
facility was also able to cut usage of supplemental fuels and
smoke suppression steam at the flare for additional savings.
In addition to the tremendous economic benefits, the
system also signifi cantly reduced plant emissions. Flaring
of hydrocarbons produces combustion by-products such
as CO2, CO and NOx that are emitted to the atmosphere.
When utilizing flare gas recovery, no by-products are
produced.
GettingStartedReduction of plant fuel consumption
Reduction of plant steam consumption
Increase in flare tip life
Rapid return on investment
Reduction of plant emissions
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Getting Started
Engineering Studies
John Zink has the engineering expertise
and equipment necessary to help customers
determine if Flare Gas Recovery is feasible
for their applicat ion. Flow measuring
equipment easily installed into existing
flare lines is available for shipment to the
job-site. This equipment automatically
stores process information over time that
is utilized by our engineering staff to tailor
the design of a recovery system to the
specific facility requirements. This infor-
mation is compiled in a report to the client
which also includes an economic analysis
of the potential payback of an FGRU
considering the capital, operating, and
maintenance costs.
John Zink has been an equipment supplier to the hydrocarbon and chemical processing
industr ies for over 70 years. As a result of this extensive experience the company has gained
a thorough view of plant and refinery needs. Our unique knowledge of flare systems and
packaged vapor recovery systems enables us to provide the most comprehensive product
designs and services available.
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SystemFeatures
Flare Gas Recovery Lease Program
John Zink Company offers a lease program for flare gas
recovery systems. We understand that even though Flare
Gas Recovery is an excellent economic choice, at times
yearly budgets or other financial constraints may mean that
the money is simply not available for project approval. With
our Flare Gas Recovery Lease Program, John Zink will design,
fabricate, and install the equipment in return for a monthly
payment after the equipment i s installed and recovering
valuable gas. The payment will continue until the end of
the lease term with provisions for early buyout. The
monthly payment made by the customer is less than the
monthly value of the recovered gas therefore the customer
can still realize a positive cash flow while paying toward
the recovery system.
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Compressor Select ion
The compressor is the "workhorse" of the FGRU. The compressor select ion and
design is crucial to the system capacity and turndown capability. During the design
phase of t he project, John Zink selects the most appropriate t ype and number of
compressors for the applicat ion. Liquid Ring Compressor Technology
is commonly used because of its rugged construction and
resistance to liquid slugs and dirty gas fouling.
However, the technical specifications
of the application might dictate
use of other types of com-
pressors such as rotary
screw, reciprocating,
sliding vane, or rotarylobed.
System Features
John Zink Company incorporates state of the art technology into the design of each Flare
Gas Recovery System. These features insure that the customer receives the most effect ive
system for the application. In addition, the systems are easy to install, require only
minimal maintenance, and are designed with safety i n mind.
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Liquid Seal
During operation the FGRU removes gas from the main flare
header. Uncontrolled, this could create an undesirable vacuum
condition in the header, and allow air to be pulled in from the
flare tip. Therefore, a positive pressure must be maintained in
the flare header by use of a liquid seal . John Zink Company is
the world leader in the design and supply of liquid seal drums.
Our liquid seal drums have
proprietary internals that insurea steady flow of gases to the
flare tip thus increasing the
maximum smokeless capacity
of the flare with the minimum
amount of supplemental energy.
Other major advantages of our
liquid seal internals include:
How
DoesItWork?
Proven performance i n numerous flares
Surge resistant internals which minimize entrainment
Minimization of noise caused by uneven combustion
Positive flame arrestor in the event of a flashback
Packaged Systems
John Zink FGRUs are skid packaged to the maximum extent
possible for ease of installation. Unlike other vendors which
supply only certain components, John Zink takes pride in
providing a complete system. Our systems incorporate
automated controls using a Programmable Logic Controller.
An Operator Interface Panel (OIP) can also be provided to
enhance the monitoring capability of key process parametersand alarms, and problem diagnosis. The OIP will allow the
operator to make system operational adjustments when
required. Desk top computer monitoring packages with
graphic displays are also available. FGRU controls can
also be integrated into an existing DCS.
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CONTROL LOGIC
HEAT EXCHANGER
DRIV E R
FLARE HEADER
L IQ UIDCOMPRESSOR
PT
How Does It Work?
St
andardFlareGasRecoveryDiagram
The FGRU withdraws gas from the flare header upstream of the liquid seal drum and
recovers gas that would normally be burned by the flare. The recovery system operates
to maintain a slight positive pressure on the flare header upstream of the liquid seal drum.
This ensures that air is not drawn into the flare system or the FGRU.
If the volume of gas relieved into the flare system exceeds the capacity of the FGRU,
pressure in the flare header will build until it exceeds the back-pressure created by the
liquid level of the liquid seal drum. At that point, any excess gas volume will begin to
flow to the flare. If the volume of gas relieved into the flare system is less than the full
capacity of the FGRU, the system is automatically turned down by staging compressors
and diverting discharge gas back to the suction header.
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ProjectExecution
RECOVERED
GA S
RECOVERED LIQUID
DISCHARGE
SEPARATORDRUM
DEEP
L IQ UID-SEAL
DRUM FL A RE
STACK
The basic operation of the FGRU using liquid ring compressor
technology is as follows: flare gas to be recovered flows
directly to the FGRU skid and into the liquid ring compressor(s).
The recovered gas and a portion of the sealing liquid combine
inside the compressor and are jointly discharged into t he
separator vessel. Here liquids and gases are separated.
Next, the compressor sealing liquid is cooled usin
