THERMIE BM./00015/96 part 1 & BM./00279/97 part2 Co-utilisation of gasified biomass and origin classified refuses (REF) and coal in CHP plant [part 1 and part 2]

Contacts




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Electricity : JOULE/THERMIE Programme : Solid Biofuels : Thermochemical Conversion

	Type of Project	Shared Cost
	Contract No	BM./00015/96 [part 1] and BM./00279/97 [part 2]
	Total Cost	11,503,500 ECU
	EC Contribution	3,000,000 ECU
	Start Date
	Duration

Co-utilisation of gasified biomass and origin classified refuses (REF) and coal in CHP plant [part 1 and part 2]

Objectives

To utilise economically available biofuels and in origin classified refuses (REF) in the existing pulverised coal-fired power plant by gasifying the fuels in a large scale CFB gasifier and by burning the hot, low-heat value gas in the boiler.

300 GWh/a biofuels and REF will be gasified and the gas will replace 30% of the annually used coal in the boiler. Correspondingly, SO2 emissions and CO2 emissions from fossil fuels will be decreased.

The expected energy savings are calculated to be 7.51 MFIM/a which equals to 1.32 MECU/a. The payback time for the investment is 9.9 years whereas the life span of the installation is 20 years.

BM./00279/97 is the second financial phase for project BM./015/96

Project Description

The large modern power plants are commonly using coal as fuel. The boilers used are often so called Benson-type once-through steam boilers since their power production efficiency is very good. For biomass it is possible to build up a firing grate inside the boiler, but it is very difficult and expensive. Furthermore, any problem in the grate can result in a shutdown of the large power plant. The space available for the grate is normally limited and the biofuel firing capacity will be small.

The atmospheric CFB gasification of dried biofuel is commercial technology. The gasification of wet biofuel is simple, but the produced gas has very low heat value and it is difficult to burn under ambient conditions. When the hot gas is led directly into the boiler, the co-combustion of the lean gas is possible in the gas burner. By means of the innovative feeding system, it is possible to adjust the moisture content of the fuel mixture, and hence the gas heat value. An expensive fuel dryer is not required.

Thus, the innovative aspects are:

1. Use of biofuels and REF in the existing once-through steam boiler by gasifying the wet fuels directly.
2. Gasification of fuels in the large scale (30-70 MW) atmospheric circulating fluidised bed gasifier.
3. Burning of lean and hot gas directly in the boiler to ensure good fuel burnout and destruction of toxic organic compounds.

The fuel prices on the following calculations of the economic aspects of the project are based on actual prices (coal, biofuels) and on budgetary proposal (REF).

Fuel	Amount GWh	Price FIM/MWh	Price ECU/MWh	Cost MFIM/a	Cost MECU/a
Coal	300	56.70	10.00	17.01	3.00
With substitute fuels:
REF	100	25.00	4.41	2.50	0.44
Biofuels	200	35.00	6.17	7.00	1.24
Total	300			9.50	1.68
Savings by coal substitution E =				7.51	1.32

During the monitoring phase after start-up, the gasifier-boiler process performance will be measured in a performance test. Based on the results, energy efficiencies of the process will be calculated. Performance of the fuel feeding system and overall process stability will be studied. The performance test period will last 4...5 weeks. The process performance will then be monitored for 1 year. During this period, the annual load and fuel quality cycles will be passed. The fouling and corrosiveness of the ashes will be actively monitored with probes and boiler inspections.

State of Advancement

Ongoing: The project started on 15 December 1996. According to the schedule, the construction work was completed by the end of 1997 and the commissioning stage including the performance tests was started in the spring of 1998. After the performance tests the process performance will be monitored for 1 year.

Contacts

Coordinator

• Lahden Laempoevoima OY FINLAND