Objective
The aim of the project is to demonstrate in full scale how to increase steam data for a steam cycle based waste to energy plant, without the normal negative side effect of severe corrosion speed. The system is mainly intended for CHP plants on Municipal Solid Waste (MSW) with a biomass fired super-heater fuelled by sewage sludge or agro-waste, in this case straw as topping cycle.
The operational experience is very positive as the output of the plant is well above the design figures and availability is comparable to conventional biomass fired plants. There are limitations in the use of the demonstration plant as it takes several hours to heat up the plant. Therefore it fits best to MSW-fired which are operated constantly in many hours (normally up to 8000 hours manned operation per year), which also affects the economics in a positive manner. In a commercial plant, a number of further improvements would be introduced, such as variable speed drive and a larger flue gas fan, flue-gas by-pass on the super-heater and changes in the fuel feed and control system.
The replication potential is obvious as Denmark is expanding the MSW incineration capacity by 8-900000 tonnes per year before year 2002. The new plants will all include electricity producing lines. The same situation is seen in many other countries. The technology can also be used to carbonise biomass or as first step in a 2-step gasifier system.
A licence agreement has been entered with ANSALDO VOELUND. Further joint ventures can be negotiated
DATA:
Straw for the basic boiler: 5.3 t/h collected within a radius of 20 km
Straw for the carbonising unit: 0.675 t/h nom, gross (0.240 t/h net)
Steam flow basic boiler: 11-26 t/h at 410-430 °C
Steam from super-heater: max. 505°C
LVH gas : 7-8MJ/Kg
LVH char: 26.8 MJ/Kg
Nominal gas capacity: 900 kW
Marginal power share: 42%
Marginal heat share: 58%
Gross overall efficiency: 78-82%
Gas production, nom.: 430 Kg/H
Char production, nom. : 245 Kg/h
Power output marginal: 250-680 kWe depending on steam data
Power output total plant: approx.5-5.5 MWe
Heat output total plant: 13 MJ/s, enough to supply approx.2500 households with district heating.
Environmental impact: Combustion of surplus straw is in principle CO2 neutral. Noise at nearest domestic area 35 dB (A) at night and 40-45 dB (A) during daytime. Slight smell.
The demonstration plant consists in essence of 1 straw carbonizer from which pyrolysis gas is extracted and used as fuel in the burner of a separate steam superheater.
Hereby the superheating temperature and subsequently for new plants the steam pressure can be increased - both resulting in a higher electrical power yield.
The technology is developed to improve the electricity-to-heat ratio on MSW-fired CHP-plants.
Corrosion speed is expected to be reduced essentially, due to reduced content of alkalimetals, chlorides and flyash in the flue gas from combustion of the pyrolysis gas compared with flue gasses from direct combustion of municipal solid waste.
The produced char is utilized as back-up topping fuel in the combustion chamber of the boiler section in order to increase and level out fluctuations in the steam flow, which will lead to increased efficiency and output. The char may also be activated and used/sold as low grade activated carbon for flue-gas or waste water cleaning..
The actual demonstration plant will be located in connection with an existing waste to energy plant in Slagelse, Denmark. The demonstration plant consists of one line with a capacity of 675 kg straw per hour.
The specific costs of the concept is approx. 16000DKK per kW marginal extra electricity output. The level for biomass fired CHP plants is in the range of 25000-36000 DKK.
The project is divided into the following phases:
1. Planning - Nov. 92 - Jun. 93
2. Engineering- Jul. 93 - Jun. 95
3. Construction and erection - Mar. 95 - Jan.96
4. Testing and take over - Apr.96 - Jun. 96
5. Monitoring - Mar. 96 - Mar. 97
Programme(s)
Call for proposal
Data not availableFunding Scheme
DEM - Demonstration contractsCoordinator
2800 Lyngby
Denmark