part 1: overview of cogeneration and its status in asia - Fire

168 Part3: Summary of country studies – Bangladesh and Viet Nam
Natural gas seems to be the most attractive fuel for cogeneration as the small deficit in
steam demand can be made up by auxiliary fuel firing in the recovery boiler. However, gas is
presently not available at the site.
As there are several other factories in the vicinity having demand for both heat and power,
one could envisage a bigger cogeneration plant for the industrial zone.
4.3.2 Textile company “B”
With an average annual production of 15 million meters of fabric, this is the biggest textile
company in southern Viet Nam. It is located in a planned centralized Industrial park in a
suburb district of Ho Chi Minh City where natural could be available in future.
With an average annual electricity and steam consumption of 42 GWh and 91,000 tons,
respectively, this company is a good candidate for cogeneration. Moreover, it has a process
cooling demand of 1,000 RT. The company has two chillers, one is centrifugal with 300 RT
cooling capacity, and the other a 750 RT absorption chiller. In alternative 2 of this analysis, it
is assumed that absorption chillers, running with steam from heat recovery boiler provide all
the cooling. About 4.5 kg/hour of steam would be necessary in a double-effect chiller to
supply a RT of cooling.
Data obtained from the electricity and fuel bills are summarized here:
• Total Electricity Consumption (12/97 to 11/98): 41,662 MWh
• Maximum Electricity Demand: 6,145 kW
• Minimum Electricity Demand: 5,200 kW
• Total Annual Fuel Oil Consumption: about 6 million litres
• Average Steam Demand: 12.4 ton/hr
The average power-to-heat ratio is 0.6, for which gas turbine cogeneration seems suitable.
Four alternatives are considered for the analysis, including steam turbine and reciprocating
engine. The results of the analysis for this company are shown in Table 4.4.
Table 4.4 Summary of pre-feasibility study of the textile mill “B”
Cogeneration Alternatives Alt. 1 Alt. 2 Alt. 3 Alt. 4
Configuration S.T. R.E. (TM) R.E. (PM) G.T.
Use of compression chiller (RT) 350 0
Absorption chiller (RT) 750 1,100
Fuel price (VND) 1,800/kg 1,430/m 3
Fuel type H.F.O. N.G.
Electricity purchase price (VND/ kWh) 800
Buy-back Rate (as % of purchase price) 56
Electricity price escalation rate (%/ year) 5
Number of actual working hours per year 7,344
Heat generating capacity (kg/hr) 15,027 12,400 4,959 16,807
Power generating capacity (kW) 1,287 15,366 6,145 8,296
Electricity consumption (MWh/year) 41,662 40,000
Thermal energy requirement (TJ/year) 287 321
Excess(+)/Deficit(-) heat (TJ/year) 0 -50 -192 0
Excess(+)/Deficit(-) power (MWh/year) -32,682 65,541 1,210 17,882
IRR (%) 20.0 20.1 27.7 24.8
NPV (million VND) 6,267.1 36,858 53,871 50,525.8