4.1 Existing System Economic Analysis
Assumptions
*It is assumed that plants of garments zone are operated for 8400 hours/year (350 days/year).
*Steam requirement in industries is 18 hrs. a day.
* It is also assumed that total steam is generated by diesel fired boilers.
4.1.1 Running cost of the existing system is cost of power and heat required by the zone
Total electricity (power) required in a year = 700*8400 kWh /year = 5880 MWh /year
Price of electricity purchased from grid is at the rate = Rs 6.50 / kWh
Cost of power required (cost of electricity consumption by garment zone) per year = Rs 38.22 million
Total heat required for a year = 2100*18*350 = 13.23 million kg Steam = 8793.981 million KCal.
(664.7 K Cal/kg calorific value of steam at 3 kg/ cm2 pressure and 1600 c temperature)
Calorific value of diesel = 10667 K Cal / kg [10].
Specific gravity of diesel = 0.85 [10]
Boiler efficiency = 85%,
Price of diesel is Rs 39 /liter
Quantity of diesel consumption in a year in liter with 85% efficiency of boiler and 0.85 is specific gravity of diesel
= 1.141 million liter /year
Price of diesel is Rs 39/ liter [11] so total cost of fuel required in a year = 1.141*39
Cost of heat required (steam generation) for garments zone in a year = Rs 44.501 million
This is the cost of diesel for generation of steam in a year by garments zone of industrial area
4.2 Proposed System Economic Analysis (CHP)
Assumption
* Fuel supplied for CHP system is natural gas.
* Loan interest is @ 12%
* Life of CHP 15 years [12] but IRR is calculated for ten years only
4.2.1 Fixed cost
Fixed cost = land cost of the plant + cost of infrastructure of the plant + cost of the CHP plant and its installation + cost of the piping system for distribution of steam
4.2.2 Variable cost
Variable cost = cost of fuel required to operate the CHP plant + O&M cost + interest over the loan amount.
Cost of fuel supplied to CHP
Quantity of natural gas required for CHP
= 419 SCM/hour = 419*8400 = 3.519 million SCM/year
Price of natural gas = Rs 15.92 / SCM [10] Total fuel cost = Rs 56 million/year
O&M cost: This is the operation and maintenance cost of the plant. = Rs 1.5 /kWh [9]
Thus, total O&M cost is Rs 8.82 million per year.
Total loan taken from the bank is Rs 79.5 million this loan amount is to be paid in six installments. Rate of interest on loan amount is 12%.Existing and proposed system economicanalysis has been shown in Table 4.1 and Table 4.2.
Table 4.1
Existing system energy and economic analysis
Sr. No.
|
Description
|
Quantity
|
1
|
Total power required in a year
|
5880 MWh
|
2
|
Total heat required in a year
|
8793.981 million Kcal
|
3
|
Quantity of diesel required for steam generation in a year
|
1.141 million liter
|
4
|
Cost of power required in a year
|
Rs 38.22 million
|
5
|
Cost of heat required in a year
|
Rs 44.501 million
|
Table 4.2
Proposed system economic analysis
Sr. No.
|
Type of cost
|
Description
|
Quantity
|
1
|
Fixed cost
|
Plant land cost
|
Rs 45 million
|
2
|
Plant building cost
|
Rs 10 million
|
3
|
Plant cost
|
Rs 20 million
|
4
|
Piping cost of steam distribution
|
Rs 4.5 million
|
6
|
Variable cost
|
Cost of fuel required to operate the CHP plant.
|
Rs 56 million/year
|
7
|
O&M cost
|
Rs 8.82 million per year
|
8
|
Rate of interest over the loan amount
|
12%
|
4.3 Internal Rate of Return of proposed system
IRR is calculated for different conditions
1. When electricity is sold at the same price as they purchased in existing system and steam is sold at the price at which it is generated in existing system and it is constant for coming 10 years.
2. IRR is calculated for same case as in condition first except constant prices for ten years but prices are varied at the rate of 10% as these varies in last ten years.
3. Price of steam sold is calculated for 15% IRR of the proposed system when second condition is followed.
4. IRR is calculated for different prices of steam sold to garments zone and remaining conditions are same. Rate of return is calculated at different prices in between Rs 2.3 to Rs 3.1/ kg steam with 10% increment in steam sold price/year.