COMBINED HEAT AND POWER by KARA

Transcription

1 COMBINED HEAT AND POWER by KARA

2 ELECTRICITY AND HEAT IN ONE INSTALLATION Renewable Electricity The market for renewable electricity production is on the move in Europe due to new EC rules, national subsidies, green certificates and rising fossil fuel prices. This means that small scale electricity production becomes financial interesting for companies that have enough biomass available for free or that can purchase biomass at a decent price. The produced electricity can be used internally and if the production is higher than the consumption the electricity can be sold to the grid as renewable energy. For companies with a heat demand these new developments can be even more interesting. The remaining energy by the production of electricity becomes available in the form of hot water or low pressure steam based on the design of the installation. For these clients a KARA Combined Heat and Power (CHP) plant is an option. Almost all energy is used useful. Therefore the client and the environment are benefiting from this option. Principal of CHP Steam is produced out of water in a biomass fired steam boiler. The steam is first lead through a turbine, where mechanical energy is made that in combination with a generator can be transformed to electricity. The steam coming out of the turbine is lower in pressure and temperature. The drop in pressure and temperature drives the turbine. The low pressure steam can be used in a process or condensed to produce hot water. The condensate is pumped back to the steam boiler.

3 KARA Combined Heat and Power Plants Every CHP plant is built according to the specific demands of the client. This is important to guarantee a system that best fits the need of that customer, because every client has its own heat and power demand, type and quantity of fuel, lay-out possibilities and environmental regulations. KARA designs CHP systems for every type of biomass e.g. sawmill wood residues, MDF dust and pruning wood - up to moisture contents of 60 wt% on wet basis. Every KARA system is tailor made and KARA can design, built and deliver the CHP plant on turn key basis. All major components, like biomass storage, transport system, the furnace, boiler and the flue gas cleaning, except the steam turbine, are engineered and produced by KARA. The main purchase part for KARA is the steam turbine. KARA has good relations with different steam turbine manufacturers and based on the preferences of the client a steam turbine supplier is chosen. But only the implementation of the steam boiler with feeding device and flue gas cleaning is another option, whereby the steam circuit and steam turbine is delivered and installed by another manufacturer. The heat and power demand is not always the same and therefore KARA CHP plants can be delivered with air heat exchangers to blow-off the remaining heat to guarantee at all times the optimum power demand. Example: 700 kw e CHP plant This CHP installation will run for at least 8000 hours a year next to a greenhouse. The electricity is sold to the national grid as renewable energy. The thermal heat comes available in the form of hot water (50 C) and is used for heating the greenhouse for at least 4000 hours a year. The fuel will be chipped wood (50 wt% wet base) from municipalities coming available when trees are trimmed in public gardens and parks. The fuel is combusted in a 4.3 MW furnace with a steam boiler on top. In this system 16 bar superheated steam is produced at 450 C. Typical flue gas temperatures out of the boiler will be around 240 C, these flue gases will be further cooled down in an economizer to a temperature below the 180 C to optimize the electric efficiency of the installation.

4 Technical details Furnace Capacity 4.3 MW Steam Pressure 16 bar(a) Temperature superheated steam 450 C Fuel Moisture Content Wood 50 wt% wb Lower heating value 7.6 MJ/kg Fuel supply 2.0 tons/hr Turbine Gross electric output 700 kw e Thermal output 2.7 MW th Installation Overall electric efficiency 17% Overall thermal efficiency 64% Electric production 5,600 MWh Renewable electric price /kwh Electric earnings /year Heat price with fossil fuel 4 /GJ Savings in fossil fuel /year Relation Electric and Heat Output The electric output depends on the needed temperature of the hot water or the pressure of the steam. Below an overview is given of the effect on the electric output when heat in the form of hot water becomes available at different temperatures with the same amount of steam. The decrease in electric output makes the case with heat at low temperatures the most interesting for implementing a CHP unit. Temperature hot water [ C] Electric output [kw e ] For Whom? Companies that should think about CHP units are: -Sawmills or Furniture producers that have drying kilns and a lot of waste wood for free. -Companies with high heat demand at low temperatures or low steam pressures throughout the year, e.g. greenhouses.

5 The Reinders Almelo Group of Companies KARA Energy Systems Almelo BV P.O.Box 570, 7600 AN Almelo. The Netherlands Plesmanweg 27, 7602 PD Almelo, The Netherlands Tel. +31-(0) Fax +31-(0) Website: