Environmental Engineering Reference
In-Depth Information
where,
C
st
= cost of heat accumulator, $
= storage capacity, m
3
m
st
11.2.4. Capital Cost of Steam Generator for Conventional MED Systems
Low pressure and low capacity steam generators are required to supply the MES
evaporator with the low-temperature thermal energy necessary to drive the unit. The capacity
of the steam generator depends on the capacity of the MES unit as well as its performance
ratio. For a unit having a
PR
= 13 and having a capacity 200 m
3
day
-1
at design conditions,
requires an estimated 0.6 ton h
-1
of low-pressure steam.
A fire-tube packaged steam generator producing steam at 10 bar and having an efficiency
(LHV) of 86 per cent is considered appropriate. The capital cost of such unit, C
b
($) is
obtained from [7] and adjusted to the current cost level using the Marshall and Swift
Equipment Cost Index. The resulting correlation is shown below:
m
s
C
=
115
,
700
+
18
,
200
×
0.15
≤
m
s
≤
12
(71)
b
12
where,
C
b
= capital cost of steam generator, $
= steam generating capacity, ton h
-1
m
s
11.2.5. Capital Cost of Diesel Generator
A diesel generator whose capacity will obviously depend on the capacity of the plant
itself can supply the electrical demand of the desalination plant. The capital cost of such
diesel generator is obtained from the following relation:
P
0
.
5494
C
dg
=
50
800
(
)
40
(72)
where C
dg
is the cost in $ and P is the rated power in kW.
11.3. Operation and Maintenance Expenses
11.3.1. Consumable Chemical Expenses
The cost of consumable items is as follows:
•
Cost of chemicals
o
Scale preventive (Belgard EV)
3.42 $/kg
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