2. Main: (403) 630 8598
Fax: (587) 329-9505
Email: miletict@mpdltd.ca
Website: http://www.mpdltd.ca
1.0 INTRODUCTION
The purpose of this document is to provide COST SAVING OPPORTUNITY for
SAGD or CSS Plants by replacing Electrical Heat Tracing (EHT) with Glycol Heat
Tracing (GHT).
Generally it is accepted that the main advantage of the Glycol Heat Tracing over
Electrical Heat Tracing is much lower capital investment and few fold lower
operating cost.
1.1 Techno-Economical Assessment GHT vs. EHT
The EHT provides a better hold temperature control of process fluids, which in
majority of cases is not a critical issue. Glycol Heat Tracing also provides means
for adequate control of hold temperature by using automated thermal control
valves.
On the surface, EHT gives impression that it is simple to install, provides good
temperature control, clean and easy to maintain. The above opinion is more or
less arbitrary determined based on individual preference or convenience rather
than actual techno-economic study.
If we consider a Total Installed Cost (TIC) it is easy to prove the cost advantage
of GHT when applied to SAGD or CSS heavy oil recovery plants. EHT system is
approximately 4 TIMES more expensive in comparison to GHT.
For example, if we assume the total Heat Tracing (HT) length is 12,000 m and if
we assume the Construction Direct & Indirect Cost are similar for both systems,
the CAPEX and OPEX will be as per the following:
A. CAPEX:
EHT: 12,000m x 497 $/m = $ 5,964,000
GHT: 12,000m x 120 $/m = $ 1,440,000
EHT /GHT CAPEX: $ 5.96 MM /$ 1.44 MM = 4.1 TIMES
B. OPEX:
EHT: Estimated EHT load 800 KW x 24 hours=19,200 KWh/day
Electrical power cost: $ 0.08/KWh
19,200 KWh/day x $0.08/KWh = $ 1,536/day
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3. Main: (403) 630 8598
Fax: (587) 329-9505
Email: miletict@mpdltd.ca
Website: http://www.mpdltd.ca
GHT: Estimated GHT load 800 KW ( total heat provided by glycol heater).
Glycol temperature: around 90 o
C
GHT temperature difference: 8 to 15 o
C
Pump volume increase 50 to 70 m3/h
Pump power increase 8 to 13 KW (28.8 $/day)
Heater gas make-up 86 MSCFD (Gas cost $5.00 x86 = $425/day)
Total operating cost: $ 425/day + $ 28.8/day = $453.8/day
From the above stated estimate the GHT OPEX option is 3.4 times more
economical than the EHT OPEX option:
EHT /GHT OPEX: $1536/day / $453.8/day = 3.4 TIMES
It is assumed, the majority of the GHT heating load will be provided simply
by recovering the waste heat from the process heat exchange units. This
will further increase the OPEX advantage of the GHT option over the EHT
option.
EHT /GHT OPEX: $1536/day / $28.8/day = 53.3 TIMES
Another example is from a recently built SAGD Plant of 36 Kbbd:
Estimated glycol tracing load is about 3.4 MW. Assuming all this duty is
supplies by the glycol heater at an efficiency of 90%, the gas make-up
required is 343 MCDF. At a gas cost of $5.0/MSCF, this works out to
$1,700/d.
Supplying the same duty with electrical power at a cost of $80/MWh and
assume 100% efficiency in conversion of electrical into heat, result is cost
of $6,500/d.
EHT / GHT OPEX: $6,500/day / $1,700/day = 3.9 TIMES
Based on the above techno economical assessment, Glycol Heat Tracing in
comparison to Electric Heat Tracing is the best feasible option to select for
process facilities with high waste heat energy content as SAGD and CSS. In
general, economical feasibility of SAGD and CSS oil recovery facilities is actually
based on the degree of waste heat recovery from process streams.
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4. Main: (403) 630 8598
Fax: (587) 329-9505
Email: miletict@mpdltd.ca
Website: http://www.mpdltd.ca
1.2 Overall Summary
The main reason to use Glycol Heat Tracing is that the required heating load is
normally contained within the integrated process heat balance such that firing of
the Glycol Heater is not always required. Practically, the GHT scavenges waste
process heat that would otherwise be lost to the atmosphere via Aerial Cooler.
If the temperature level of the recovered waste heat from hot process streams is
not sufficient, then the glycol heater should be fired to make up the difference.
This situation may occur during some of the winter extremely cold periods. At this
point, the waste heat issue would be dependent on the efficiency of heat
recovery, or costs of the purchased power from the electric power grid versus the
efficiency of heating glycol firing.
During plant start-up, electrical power is always necessary for running Glycol
Circulation Pumps and the fluid circulation through integrated Glycol
Cooling/Heating System. In the case of GHT there is relatively a small increase
of power requirement to run the Glycol Circulation Pump due to additional
circulation flow rate increase, although the power increase is almost negligible in
comparison to the overall power requirements for EHT.
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