Transcript Natural Gas Hydrate ** Mannel , * Transportation ** Puckett , David David and Miguel Bagajewicz University of Oklahoma- Chemical Engineering (*) This work was done as part of the capstone.

Natural Gas Hydrate
**
Mannel ,
*
Transportation
**
Puckett ,
David
David
and Miguel Bagajewicz
University of Oklahoma- Chemical Engineering
(*) This work was done as part of the capstone Chemical Engineering class at the University of Oklahoma
(**) Capstone Undergraduate students
Economic Comparison
Natural Gas Hydrate Synthesis
Abstract
We investigate the possible use of hydrates for natural gas transportation using shops. Natural gas hydrates were
found to be economically less favorable than LNG for the transportation of natural gas. However, natural gas
hydrates were found to be economically viable for small capacity peak-shaving plants and natural gas storage.
Natural Gas Hydrates
Liquefied Natural Gas
CSTR cost $1,760,000
Compressor Equipment Cost:
Recycle Compressor Cost: $2,200,000
Intake Compressor Cost: $870,000
LNG TAC per ton
NGH TAC vs Capacity
180
300
Increasing distance increases the TAC/ton.
Adding ships causes a sharp increase in TAC/ton.
-
160
140
250
Total Cost: $3,070,000
-
120
0 miles
1000 miles
200
2000 miles
100
1000 miles
3000 miles
($/ton)
0 miles
$/ton
Hydrates
Heat exchanger cost
Initial Cooling Heat Exchanger Cost: $235,000
Post Cooling Heat Exchanger Cost: $113,000
Natural gas hydrates are a small molecule of gas (methane,
ethane, propane) that become encapsulated in a cage of water
at low temperatures and high pressures.
Increasing distance
increases TAC/ton.
2000 miles
4000 miles
5000 miles
80
6000 miles
3000 miles
150
7000 miles
4000 miles
Pump cost:
$690,000
8000 miles
60
5000 miles
9000 miles
10000 miles
40
100
20
50
The natural gas hydrates are produced in a stirred tank reactor, and then they are frozen into blocks and loaded onto ships. The required fixed
capital investment is $23,000,000 with a production rate of 1.5 million tons per annum. All equipment prices are given for a production of
1.5 million tons per annum.
Peak-Shaving
0
0
200000
400000
600000
800000
1000000
1200000
1400000
1600000
1800000
2000000
0
500000
1000000
1500000
2000000
2500000
3000000
3500000
4000000
Capacity (tons)
Capacity (tons)
LNG 0 miles
100
Natural gas hydrate peak-shaving has a lower
TAC/ton and FCI/ton than LNG.
NGH vs LNG Peak-Shaving
A positive ROI occurs with sales of
$100/ton for low production capacities.
80
A positive ROI occurs with sales of $80/ton.
25
60
20
NGH vs LNG Peak-Shaving
Natural Gas Hydrate Transportation
15
Ambient Temperature
Tank Outer Diameter
29.5 m
Tank Thickness
0.31m
Steel Weight
113000 tons
400
10
5
($/ton)
300
250
NGH FCI/ton
200
LNG FCI/ton
150
NGH TAC/ton
50
LNG TAC/ton
LNG ROI ($100/ton)
0
-5
100
Atmospheric Pressure
Tank Outer Diameter
29.5 m
Tank Thickness
3.65mm
Steel Weight
1300 tons
NGH ROI ($100/ton)
%
350
0
-10
1000000
2000000
3000000
Capacity (tons)
Capacity 145,000 metric tons
Capacity of 186,000 m3
Length 290m
Beam 45m
Draught 18m
Base price $165,000,000
0
40
20
40
60
ROI (%)
-
80
20
100
120
140
160
0
0
3585
40 ton ice-hydrate
blocks required
500000
1000000
1500000
3500000
4000000
180
-40
Natural gas hydrate peak-shaving has a
higher ROI than LNG.
Capacity (tons)
3000000
-20
-60
500000 1000000 1500000 2000000 2500000 3000000 3500000
2500000
200
0
0
2000000
Capacity (tons)
LNG 4000 miles
NGH ROI 4000 miles
80
10
As distance increases the sales increases to slightly above
$120/ton to maintain a positive ROI.
The TAC/ton, FCI/ton, and ROI is better for NGH with transportation distances of 0 miles.
As distance increases the sales increases to $180/ton to
maintain a positive ROI.
60
5
40
0
0
0
2000000
4000000
6000000
8000000
10000000
20
40
20
60
40
-5
60
80
120
0
0
500000
1000000
1500000
2000000
2500000
3000000
3500000
4000000
140
80
ROI (%)
100
100
120
-10
140
160
160
180
LNG
12000000
0
20
ROI (%)
NGH is a better option for peak-shaving the cost of natural gas.
The ships have small refrigeration units to keep the blocks of hydrate frozen, since they are shipped at atmospheric pressure.
For a shipping distance of 4,000 miles and 1.5 million tons of hydrate per annum, the fixed capital investment for shipping the natural gas
hydrates is $1,100,000,000.
180
200
200
-20
-15
Natural Gas Hydrate Regasification
-40
-20
Natural Gas to
Water Removal
44 pressure vessels:
V = 294 m3
$5,400,000
Costs are taken as the average costs for a range of plant designs.
PC
FC
776 storage vessels:
V = 150 m3
$30,000,000
Pressure
Vessel
Heating Kettle
Condensate
of 1 mtpa, 2 mtpa, and 3.5 mtpa.
Heating Costs for the kettle
Liquid Water
Found using the heat of dissociation of methane hydrates, the
specific heats of hydrate and water, and the required gas flow
rate.
Solid
Ice-Hydrate
Cost data for LNG was obtained at plant capacities
-60
Low Pressure
Steam
Capacity (tons)
Capacity (tons)
LNG has a lower TAC and a higher ROI.
LNG is a proven and well developed technology.
LNG is a better option than NGH for the transport of natural gas.
Cost of 1 MM BTU assumed to be $7.33
Total heating cost
$40,000,000
Ballard, A. L., & Sloan, E. D. (2001). Hydrate phase diagrams for methane + ethane +
propane mixtures. Chemical Engineering Science (53), 6883-6895.
Shipping costs are contracted out at $65,000/day for 57,000 tons LNG. The total annualized cost for a LNG tanker is less than $23,000,000/year, or $63,000/day.
Contracting out the shipping is the worse case scenario for LNG.
-25
The blocks of hydrates are decomposed in a pressurized vessel, and then leaves the vessel at pipeline pressure.
The fixed capital investment for the regasification facility is $140,000,000 for a production rate of 1.5 million tons per annum.
Englezos, Kalogerakis, Dholabhai, & Bishnoi. (1987, November). Kinetics of formation of
methane and ethane gas hydrates. Chemical Engineering Science , 2647-2666.
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