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vfdamike@alaska.com
From:
<EnerConcep@aol.com>
To:
<vfdamike@alaska.com>
Sent:
Thursday, July 20, 2006 10,34 AM
Attach:
VFQA report by ECC.doc
Subject:
Valdez cold storage warehouse
Attn: Jason Wells
Dear Mr. Wells:
Energy Concepts is pleased to forward the attached report entitled, "Waste Heat lowered Absor Lion Refrigeration ni
far Valdez Fisheries Development. Association Cold Storage Warehouse".
This report documents the feasibility of using waste heat available at the Petrostar refinery to produce 400 tons of minus
30°F refrigeration, and estimates the cost of the ARU. The study was authorized by your letter dated May d, 2006.
We estimate the installed cost of the 400 ton ARU (two 200 ton units) to be $2,770,000. This includes the evaporative
:ondensers. This is essentially the same cost as Anvil estimated for vapor compression refrigeration. Hence there sha Id
ae little or no cost premium for adopting this more efficient, lower operating cost technology.
dVe will be commissioning a similar waste heat powered double lift ThermoChilier next month in New Mexico. It als
rroduces minus 30°F refrigeration from refinery waste heat.
will be happy to answer any questions you have about this report, and to receive your comments,
yours Very truly,
)onald C. Erickson
'resident, Energy Concepts Co.
i27 Ridgeiy Ave.
knnapolis, MD 21401
�c. A 7
7/20/2006
WASTE HEAT POWERED ABSORPTION REFRIGERATION UNIT FOR VALDEZ
FISHERIES DEVELOPMENT ASSOCIATION COLD STORAGE WAREHOUSE
Energy Concepts Company
Annapolis, MD
July 20, 2006
INTRODUCTION
It is proposed by the Valdez Fisheries Development Association (VFDA) to construct a
cold storage facility in Valdez.
It is further proposed to keep the operating cost of this facility low by producing the
refrigeration from waste heat, which is available at a nearby PetroStar oil refinery.
A conceptual engineering report was concluded. in September 2003 by Anvil Corporation
(Alaska Anvil Report AE 1493 Rev. 0, September 19, 2003) which estimated the project
costs. The design refrigeration load was calculated to be 400 tons. Liquid ammonia is
pumped at —30°iF to air handlers in each of twelve storage modules, to maintain the
modules at —20°F. The waste heat powered absorption refrigeration unit was not
designed, but was assumed to be feasible. The cost estimate concluded that the
absorption -based system would cost $6.5 million dollars more than a system using a
conventional vapor compression refrigeration plant. Almost all of the cost difference was
due to the assumed high installed cost of absorption refrigeration - $9.2 million versus
$4.1 million for vapor compression.
When using modern absorption refrigeration technology as practiced by Energy
Concepts, the capital cost and installed cost at these conditions (-30°F evaporator) should
be very comparable between absorption and compression. Accordingly, VFDA
commissioned Energy Concepts to provide an independent cost estimate of only the
absorption refrigeration portion of the project, including a preliminary engineering design
to confirm the feasibility and practicality of the waste heat firing.
This report presents the preliminary engineering design plus the cost estimate for the
absorption refrigeration plant.
WASTE HEAT AVAILABILITY
The source of waste heat for this project is the overhead condensation duty for the crude
column at the PetroStar refinery. At the design rating of 46,000 barrels per stream day,
the overhead vapor is at 218°F and. 17.1 psig. It is cooled to 106°F in an air-cooled
condenser, with a duty of 46 million BTU/hour. The heat release curve for this
condensing light straight run (LSR) oil is quite linear, which means that 17.25 million
BTU/hour is available by cooling to 176"F. This is sufficient to power the ARU design
reported herein. The stream is not particularly corrosive. Conventional carbon steel shell
and tube heat exchangers are presently used for that duty, and Anvil specified and costed
similar exchangers to gather the waste heat.
Enem, Concepts Cc July 20. 2006
There are two issues to be ascertained regarding availability of this heat. First, what is
the impact of the increased pressure drop imposed by the new partial condensers, placed
in series with the existing fan coil? A typical added AP would be 1 to 1.5 psid. The
refinery has given assurance that they can elevate column pressure up to as high as 20
psig if necessary, so this added ❑P will not be an issue,
Secondly, will this waste heat be reliably available, especially during periods of 111ghest
refrigeration demand? The refinery indicates that the greatest demand for its products
(diesel and jet fuel) is during the summer, so they operate ail -out then. Indeed, the
refinery is bottlenecked by existing air-cooling capacity, and welcomes this project as
providing de -bottleneck assistance. The refinery turnaround is in late spring, when
refrigeration demand is very light.
The refinery heat source is located about 600 feet from the planned cold storage
warehouse. Anvil specified and costed a pumped glycol loop for that duty.
The question of providing a backup meat source for the absorption unit during unplanned
refinery upsets is addressed separately.
REFRIGERATION REQUIREMENT AND AMBIENT TEMPERATURE
The design refrigeration load is 400 tons, at minus 30"F. A liquid overfeed system
maintains the refrigerated space as low as minus 20°F. The 11/' design ambient
temperatures for Valdez are listed in the ASHRAE Handbook as 66 °F dry bulb talus 550F
mean coincident wet bulb.
ABSORPTION SYSTEM DESIGN
The driving heat will be delivered via a heat transfer fluid, e.g. glycol. After heat
exchange with the 218°F source, and transport through about 600 feet of supply piping,
the temperature is 209°F. It is cooled by 40°F while releasing. 16.5 million BTU per
hour, and returns to the refinery at 168°F.
With heat at this low a temperature, it is not possible to reach minus 30°F with a
conventional single effect (two pressure) absorption cycle. Accordingly a three -press :rc
("double lift") cycle is selected. This cycle can reach the required evaporator
temperature, given the Valdez ambient conditions. Notwithstanding that, the
conventional three -pressure cycle has a Iow COP, and would require more waste heat
than is available. Accordingly we designed a high efficiency version of the three -
pressure cycle, with COP of 0.29. This COP is I 3%0 higher than the standard 3P cycle at
these conditions, and achieves a match between the required heat (16.5 MBH) and the
heat available (17.25 MBH).
The resulting cycle is depicted in the Figure ] schematic flowsheet.
(Deleted due to proprietary information)
farm Cnnceprs Cn. Juh• 20. 2006
DESCRIPTION OF OPERATION
Waste heat is input to both the high pressure generator (HP GEN), and intermediate
pressure generator (IP GEN), in parallel. Each generator has an associated rectifier (HP
Rect and IP Rect), which purifies the overhead ammonia vapor to the desired
concentration. The HP Rect has internal heat exchange: both below the feed point (HP
GHX) and above it (HP Solution Cooler Rectifier). Purified vapor from HP Rect is
condensed in the Evaporative Condenser, then precooled in the Refrigerant Heat
Exchanger (RHX), then expanded into the evaporator in the cold storage warehouse. The
resulting low pressure vapor, after warming in the RHX, is absorbed in the Low Pressure
Absorber (LP Abs). The resulting solution is pumped by the LP pump to the IP Rect and
IP Gen. The vapor from the IP Rect is absorbed in the IP Absorber, and the resulting
solution is pumped by the HP pump to the HP Rect and HP Gen. Cooling fluid removes
heat from each absorber. This fluid is cooled in the evaporative condenser. This
completes the cycle. The design thermodynamic: conditions for all the cycle state points
are tabulated in Tablel. This table depicts a 200 ton design rating such that two units will
he required for the complete installation. This allows a phased construction process,
starting with only a single unit.
Energy Concepts Co. Jab• AM .7006
Table I. Valdez ThermoChilier Statepoints
(Nate: Tabulated flow rates are for 200 ton capacity — 2 units are required.)
Enerv, Concepts Co. Jith ?0, TOOA
COMPONENT DESIGN
Table 2 presents the duty and UA rating for each heat exchanger. Thcse sizes are within
the range of availability of the standard components used by Energy Concepts for these
cycles. The heat exchangers are all fabricated from stainless steel, and are either shell and
coil design or brazed plate design. This results in a very compact apparatus. The
estimated footprint for each 200 ton skid is estimated at 8 feet by 12 feet.
Table 3 shows the head and capacity rating for each pump, and estimated electric power.
Table 2. Component Heat Duties and UA Values far %-'aidez ,rhermoChiller
(Note. Tabulated heat duties are for 200 ton capacity -- 2 units are required,)
Component
Heat Duty
UA Value
CON❑
725.9 kW
( 2.48 MMBtulhr }
142,436 W/K
{ 0.270 MMBtulhr-F }
RHX
137.5 kW
( 0.47 MMBtulhr j
17,100 WX
( 0.032 MMBtulhr-F )
EVAP
703.4 kW
2.40 MMBtulhr }
_
LP-ABS
1223 kW
{ 4.17 MMBtulhr j
80,607 WIK
( 0.153 MMBtulhr-F j
IP-SHX
545.1 kW
( 1.86 MMBtulhr j
131,420 WIK
{ 0.249 MMBtulhr-F
IP-SCR
127.2 kW
( 0.43 MMBtulhr }
3.740 W/K
[ 0.007 MMBtulhr-F }
IP-GHX
125.7 kW
( 0.43 MMBtulhr j
16,197 WX
{ 0.031 MMBtulhr-F }
IP-GEN
1376 kW
( 4.69 MMBtulhr j
304,641 WIK
( 0.578 MMBtulhr-F )
1P-ASS
1210.4 kW
{ 4.13 MMBtulhr)
76.161 WIK
( 0 144 MMBtulhr-F j
HP-SHX 1
694.4 kW
( 2.37 MMBtulhr J
72,620 WIK
{ 0.138 MMBtulhr-F }
HP -SCR
90.3 kW
{ 0.31 MMBtulhr }
1,862 WIK
{ 0.004 MMBtulhr-F }
HP-GHX
81.9 kW
( 0.28 MMBtulhr j
11.560 WIK
( 0.022 MMBiulhr-F }
HP-GEN
1075.4 kW
( 3.67 MMBtulhr }
222,587 WIK
( 0.422 MMBtulhr-F )
Table 3. Pump Specifications for Valdez ThermoChiller
(Note: Tabulated pump specifications are fir 200 ton capacity — 2 units are required. j
Flow Rate (gpm)
dead {ft}
ideal power (kWe)
HP Pump
57.6
356
2.7
LP Pump
79.1
151
1 3
Energy CmvWs Ca. Juf p 20. 2006
BACKUP HEAT
The absorption refrigeration unit must continue to function during periods when the
refinery waste heat is unavailable, whether clue to scheduled turnarounds or upsets. This
could become a costly undertaking if the fuii 16 million BTU per hour input were
required. However, by supplying the backup heat at a higher temperature, e.g. 280"F vs.
the 210' waste heat, a more eMcient single effect cycle is possible. This nearly doubles
the COP, from 0.29 to 0.54. That reduces the backup heat requirement to 8,5 million
BTU1hr, while still maintaining the minus 30°F output and full capacity.
Energy Concepts has devised a straightforward four valve switching mechanism which
changes the cycle between single effect mode and double lift mode. The feature has been
field tested at the ThermoChiller installed at Chena Hot Springs, Alaska. There they use
single effect mode in spring and fall, and double lift mode in summer.
Energy Concepts will add this feature to the Valdez. ARU. This reduces the size of the
backup hot water boiler to 8.5 million BTLlihr, and also eliminates half the fuel storage
need. The fuel storage can be combined with that for the backup generator. As shown by
ANVIL, the required size of the backup electrical generator is greatly reduced when
using absorption refrigeration, since the vapor compression load is eliminated.
A suitable hot water boiler is manufactured by Un1lux . The firing rate is 10 million
BTUIhr, and the hot water heating is 8.5 million BTU/hr. The quoted price is $68,000.
This agrees reasonably well with the ANVIL estimate of$77,000. However the ANVIL
estimate of $145K to install this boiler is considered excessive, by about $70K.
ESTIMATED COST
For each 200 ton absorption skid, the purchased components total $275K, and tlic factory
FOB cost is estimated at $850K. The associated cooling tower (evaporative condenser) is
estimated at $175K. The combined cost for the 400 ton system is $2,050K. These
numbers agree very closely with the Anvil estimates, as shown in Table 4 below, The
comparable vapor compression FOB cost ($2300 K including cooling tower) is taken
directly from the Anvil report.
Where Energy Concepts takes issue with the Anvil costing is in the cost of installation.
Anvil estimates that installing the vapor compression refrigeration plant will add 25% to
the cost, or an additional $575K. In contrast, they estimate that installing the absorption
refrigeration plant will add 230% to the cost, or an additional $4,485K.
In Energy Concepts' experience, installation of a modern absorption refrigeration unit is
simple and low cost, adding on the order of 35% to the cost ($720K for the Valdez
installation). Our estimate of installed cost is presented in Table 4, including the
comparison to the Anvil estimate. It is important to note that the installation costs for
various auxiliary systems, such as the waste heat recovery system, the back up boiler plus
fuel storage, backup electrical supply, etc. are separately tabulated in the Anvil report, i.e.
they are not overlooked.
Energy ConceP3 Ca, Juh 20. 2006
Table 4. Cost Estimate Comparison
Refrigeration Plant for Valdez Fisheries Development Association
Cold Storage Warehouse
I. Raw Cost Estimate of Refrigeration Plant (from Anvil Conceptual Engineering Report)
Condensing Unit, including evaporative condenser, not including elcctric service or
HRVG.
Hardware
Installation
Vapor Compression
2,300,000
575,000
Abso Lion
1,950,000
4,450,000
II. Fully Burdened Cost Estimate (from Anvil Conceptual Engineering Report)
(all costs escalated 43.75% to cover engineering and contingency)
Hardware
Installation
Vapor Compression
3,306,250
826,563
Absorption 12,803,125
6,396,875
III. Energy Concepts Company Cost Estimate (not burdened)
Hardware Skidded Unit) Installation
Abso tion 2,050,000 720,000
F.rrrrr i Concepts Co. July 20. 2006
CONCLUSIONS
I. It is feasible to power a 400 ton absorption refrigeration unit with waste heat from the
Petrostar refinery. This will be beneficial to the refinery,
2. The absorption refrigeration unit can readily be supplied as two essentially identical
200 ton units, each as needed, thus reducing the required up front investment.
3. The FOB cost of each absorption unit is estimated at $850K, and the associated
evaporative condenser at $175K.
4, The total absorption system FOB cost of $2050K agrees closely with the Anvil
estimate, and is to be compared to $23OOK for vapor compression (per Anvil).
5. The cost of installation of both absorption units plus evaporative condensers is
estimated to be $720K.
G. Anvil estimated the cost of installation of the absorption unit about $3.5 million higher
than Energy Concepts. After inflating the difference by 43% to account for engineering
plus contingency, it accounts for most of the $6.5 million difference in total cost
calculated by Anvil.
7. It is concluded that the two refrigeration systems will cost approximately the same
installed. When the costs for all auxiliary systems are included for each refrigeration
system, the premium which must be paid to obtain the operating savings of the waste heat
powered plant (estimated at about $40OK savings per year) is less than one million
dollars.
F.nergy Concepts Co. July 20. 2006
SUMMARY RESULTS
Cost Estimation Procedure
Waste Heat Powered Absorption Refrigeration Unit for Valdez (VFDA)
July 20, 2006
1. Obtain/ascertain refrigeration requirements
■ Load profile (annual); peak load = 400 tons
it Temperature (-30'F)
■ Capacity (400 tons)
■ Review Anvil report and McDowell reports Done
2. Obtain/ascertain details of waste heat availability from Pelrostar refinery
■ Form column overhead condensing duty, 18 prig
■ Allowable pressure drop 1 to 2 psi
■ Load profile (annual) (17.2 MMBTU/hr steady)
■ Temperature glide characteristics (21$°F—* 176°F)
■ Corrosive mild steed OK
■ Accessibility ground level
■ Distance to refrigeration load, transport considerations --600 feet, transport OK
3. Heat rejection
■ Ambient temperature and humidity profile 660FDB t 55°F YVB, ASHAAE PS
■ Cooling water available cooling tower supplied and costed
■ Makeup water available? Water purity? yes —acceptable purity
■ Drycooling not necessary
4. ARU preliminary design
■ Cycle design to satisfy load
o Adequate heat? yes
o Single stage or two stage?
■ Component design and sizing
o Absorber(s)
o Rectif er(s)
o Heat recovery coil
o Heat rejection
o Dthcr exchangers
o Pumps
Two stage
see component sizing and UA table
5. ARU system cost estimation (see cost cable)
■ Vendor pricing incorporated in estimate
■ Components only
■ ARU cast estimate ECC: $1,7 million (ARUs plus 3350K Evap Condensers)
■ Heat recovery system cost estimate Anvil: 3520K installed
ARU ship and install cost estimate ECC: 35% of ARU cost = $720K
Entry Concepts Co. July 20, 2006