Score - Sustainable Construction in Rural and Fragile Areas for Energy efficiency
Guidelines for Integrated territorial Planning:
Biomass
Guidelines for integrated territorial planning – Biomass stove
“Smart house” exploits solar energy for water preparation that is used for room heating and sanitary water with greater panel’s installations. At lower temperatures the water in reservoir is heated with help of a heat pump and at peak times or increased use with remote biomass heating. “Smart house” with remote wood chip heating distributes heat also too the nursery school, post office with parish house, rectory and church. Heating boiler brand is KWB, type MULTIFIRE USV 100, Q=100 kW, which is sufficient for heating a complex of the building, premises and any customer of heated energy. Special biomass boiler is designed for system with automatic fuel dosing from biomass landfill at the boiler.Boiler is equipped with a compact heat exchanger with a large heating surface and buit-in turbulators for better heat transfer. Installed turbulators with cleaning function ensure the maximum sustained boiler efficiency. High temperatures of the flue gases in the entry area of heat exchanger are providing immediate heat exchange and intense flow of water convection.
The boiler is equipped with the KWB burner by dosing from the bottom, with screw conveyors, with a ring burner with nozzles, high-temperatures dome and the turbulent combustion zone. Up to three hours after burning maintains embers, after that follows the ignition with help of hot air. Primary and secondary air supply is regulated through help of a radial ventilator with controllable speed. Firebox is also equipped with suction tracking to maintain regulatory vacuum. The fuel sensor monitors the current necessary level of fuel (depends on fuel and thermal power).
Safety in the boiler is provided with appropriate facilities. Security systems are multi-level, independent among each other, easy to be controlled and composed of: verified anti-lightning protective unit, air-tight fire closing flaps, which represents firefighting barrier, thermal protective valve that works without electrical power and controls the temperature in the dosing channel, intermediate reservoir with optical electric charge level regulation, inclusive mechanical guard against overloading and safety temperature limiter. Fire shutter and thermal safety valve operates independently of electric power failure. Thermal safety valve is supplied from a water reservoir which has built-in a water level sensor and is fitted on the boiler. Moreover, there are minimum/maximum fuel limits in the burner and electronic, as well as mechanical control of ignition.
Vertical KWB tube heat exchangers are directly above the combustion zone and allow automatic ash cleaning. Two of the tungsten carbide coating protected snails condense and supply the entire ash of the device in outer container, which can be easily removed and emptied. The boiler is designed exclusively for burning wood residues (wood chips). Wood chips may not be surrounded with preservatives, impregnation, adhesives or coatings.
Water-heated system allows protecting boiler from to low temperature of returned boiler water (with a tree way valve for the adulteration of water). Heat transfer to individual users is executed only after the water in boiler is heated to operating temperature.To reduce the number of switching of the boiler there are installed two heat storage tank, V=1000L, which are heated continuously during operating of the boiler. Wood chips dump is in the room next to the boiler room (energy room).
Pipelines in the boiler room are steeled, mounted and placed with insulation of 7 cm thick mineral wool layer and covered with aluminum sheet. Watershed from the boiler to a single substation is performed in the soil. Watersheds are constructed of polypropylene pre-isolated pipes and are equipped with leak detection to help determine the possible site of leaking. Heated water is transported true a remote heat pump with the proper pump using proportional regulation.
The boiler is equipped with a control box with regulation and lambda regulation monitoring:
- Protecting achieved high temperatures in the combustion chamber,
- Level control of material in the downward tube,
- Pressure control,
- In combination with mono/ulty cyclone maintains a constant pressure in the boiler,
- Temperature control of the return to the boiler,
- Remote alarm warning – GSM grid,
- Automatic fault warning and temperature control,
- Visualization.
Indication for the Bio-construction Action Plan
- The reason for the slow biomass breakthrough into key energy sources are high technology costs and low awareness of the people. Compared with the equally efficient fossil fuel stove are combustion biomasses stow definitely more expensive and this is certainly a key reason why they are not widely used. It is understandable that only individuals decide for relatively expensive investment in biomass combustion stove which is in current situation justified only in the long-term.
- Efforts should be made to reduce technology costs of biomass energy production, which will lead to reducing the financial help from the state. Some countries are in fear of smaller budget inflows, since the use of biomass would reduce the fossil fuel consumption and therefore would collect less taxes of CO2 and consequently it is difficult to expect adequate state measures.
Possible criteria for MED bio-housing quality certificate
- Biomass combustion stove must have consistent with the EN 303-5 standard (for fireplaces EN 14 785), following heat-technical characteristics: efficiency at native heat power must be larger or equal to 90%, value of total dust emissions should be less then 50 mg/m3, emission of carbon monoxide should be lower then 750 mg/m3 (emissions defined at temperature 273 K and pressure of 101,3 kPa and calculated oxygen content 13% in dry flue gases).
- In recent years were in the field of solid bio-fuels in the European Union accepted number of standards. Among most important are those which define the quality of wood fuel and specify procedures to ensure it. The standards are not binding in principle yet they are an important tool in the negotiation between buyers and suppliers of wood fuel on the market. Most important properties of wood fuels specified by the standards are: dimension, market type, water content and heating value. In order to devices and systems to operate smoothly and optimally, is necessary to analysis quality of wood fuel.
- For further developments in this field it would be important to expand standardization of wood fuel market and also regulate the market. One of the main obstacles for further development of wood biomass is currently confidence in the sustained quality energy supply.
Case studies
− Bistra hiša - Smart house (Martjanci, Slovenia)