Type of CHP system: Grate fired boiler

Plant owner: Renova is owned by Göteborg city and municipalities surrounding Göteborg.

Commissioned: (reconstructed):1972 (1994)

Status of plant: Commercial

Contractor details:

Two boilers is manufactured by von Roll AG,one by Martin Gmbh. Turbine by Alstom

(former ABB). Wet flue gas cleaning by Götaverken Miljö AB, dry cleaning by Alstom

(former ABB). Four absorption heat pumps by Sanyo and two by Entropie.

Power generation: Steam turbine

If the waste is directly incinerable it is emptied directly to the bunker. Bulky trash, industrial

waste first passes through preprocessing plants and after that the waste is transported

to the bunker.

The condensation flue gas cleaning system consists of the wash reactor and the condensing

reactor. Over 60% of the humidity in the flue gas is condensed to water when the gas is cooled.

To obtain good contact between gas and water and an efficient heat transfer, the condensing reactor

is fitted with scrubber packing. Series of droplet separators in the condensing reactor is used to

separate very small droplets of water.

The water in the condensing reactor is circulated through a heat exchanger. Via the intermediate

cooling system the heat is transmitted to the absorption heat pumps and the district heating

system.

After the condensing reactor the flue gas is reheated to appr. 85 degrees C. In the fabric filter

the discharge of sulfur and dioxins is reduced.

Slaked lime and active carbon are here added to the flue gas. Large cloth-covered tubes which

catch the mixture of pollutants, lime and carbon are found in the filter chambers.

Main fuel:

Municipal and industrial waste.

Three incinerators, 2 using 22 ton/h,

1 using 15 tons/h. In year 2004, 433 000 tons was incinerated. Appr. 22% moisture

Nominal capacities & efficiencies:

Thermal input, biomass & waste: 177 MW

Total thermal input, incl. fossil fuels: 177 MW

Gross electrical output: 32 MWe

Net electrical output: 24 MWe

Heat output: 150 MJ/s

Electrical efficiency, gross: 17 %

Electrical efficiency, net: 13,5 %

Overall efficiency, gross: 94 %

At full load there is no need for fossil fuels. Flue gas condenser about 24 MW

Condensation 58 MW

How is plant controlled: Mainly the heat demand and by the amount of waste that has to be disposed of.

Heat usage: Heating and process steam

Energy usage:

The district heating is sold to Göteborg Energy AB and used in Göteborg city.

The electricity is sold to Göteborg Energy AB.

In Göteborg lives appr 420 000 inhabitants many of them is supplied with district heating.

Renova supplies the city with appr. 26% of

the total amount of district heating.

District heat coverage (% of total demand in DH network): 26 %

DH inlet temperature: 85-115 °C

DH return temperature: 42-50°C

Heat storage size: No accumulation tank m3

Hours of full load that the heat storage can meet: No accumulation tank

Fuel storage: 11 000 ton. 7 days

Waste water:

With the use of finely ground limestone and a solution of slaked lime

(or 25% caustic soda) the pH value is adjusted to 9.

A precipitating agent is used to bind the pollutants and a flocculation agent is used in

the sedimentation process. The treated water finally goes through a sand filter or active carbon filter and is

pumped to the Göta River.

In the water cleaning plant a absorption heat pump is used to reduce the temperature of the water.The recovered heat supplies the district heating system.

Ash discharge:

Fly ashes are mixed with sediment from the water cleaning system. A precipitating

agent (an organic sulfide) is used to bind the pollutants and form sulfide compounds that

are nearly insoluble. This mixture is transported to a landfill.

The slag is transported to the landfill site where sorting and recovery facilities

contribute to furtherreduction of volume.

Scrap metal and gravel fractions will be recovered.

Plant description:

Renovas waste to energy plant is located at Sävenäs in Göteborg. The plant treats

incinerable waste which comes primarily from municipalities in the Göteborg region.

The plant consists of three incineration lines.

Each line has a furnace for incineration, a steam boiler, an electrostatic precipitator,

a condensation flue gas cleaning system and a fabric filter cleaning system.

The plant is licensed to incinerate 550 000 tons per year.

The steam produced runs a turbine and a generator. When it leaves the turbine the

steam is led to the condenser where it is used for production of heat to the district heating system.

After the electric precipitator the flue gas passes an economizer where the temperature is reduced and the heat is supplied to the district heating system.

In the condensation flue gas cleaning system the water in the condensing reactor is circulated through a heat

exchanger. The recovered heat is transmitted to the district heating system via the intermediate cooling system and the absorption heat pumps. The acidic process water which comes from the condensation flue gas cleaning system is treated in the water neutralization and cleaning plant. The treated water goes through a sand filter or active carbon filter and is pumped to the Göta River. In the water cleaning plant a heat pump is used to reduce the temperature of the water.The recovered heat supplies the district heating system.

www.renova.se

Fuel feeding system:

From the bunker overhead cranes is transporting the waste to the feed shute for each incinerator. At the bottom of the shute the feeders pushes the waste forward in to the grate. The feeder is controlled by the computer system running the incinerator.

Boiler: Self circulating watertube boilers.

84/85/85 % efficiency /boiler.

Turbine: 36 MW nominal effect.

1 st Turbine condenser

1 st reserve condenser

Steam data: 40 bar, 400 degree Celcius, 198 tonnes/hr (3 units)

Flue gas cleaning:

The electric precipitator takes care of most of the fly ashes. The wet flue gas cleaning system is very efficient to most of the pollutants. The fabric filter is mainly built for the reduction of SO2 and dioxin. Reduction of

NOx is done in two steps. A part of the flue gas (after the precipitator) is recirculated back to the furnace to reduce the NOx. Ammonia 25%, is injected in to the furnace which also reduces the NOx.

Cooling system:

3 cooling towers for use in summertime when the district heating system is reduced. Water from the Säve River is sometimes used in heat exchangers to reduce the temperature in the intermediate cooling system (flue gas condensing system/heat pumps).

There are two additional steam systems. One 3,5 bar used for the heat pumps, reheating the flue gas etc.

One 7 bar system used for NH3 injection, feed water heating etc.

Staff:

105 employees including staff and workshop.

To operate the plant, 6 employees. Additional staff is needed for registering weight, traffic managing, handling the slag etc.

At night 6 employees is needed.

Electricity sale info:

The tarif is not the same all over the year. It is parted in seasons. Up to 90% of the tarif is a fixed price and the rest is dependent of the market.

Total capital cost: € 16,407,000

Year 2002

Data collected and quality assured by: Swedish Biomass Association.

Contact person: Johan Vinterbäck