General description of heat generators, operating principle
Heat generators consist of 3 or 4 main parts depending on capacity of model which include: 1) Furnace, 2) Accumulating tank, 3) Auxiliary tank and 4) Chimney.
Cylindrical combustion chamber is built into water chamber that provides reliable cooling of radiant heat absorbing surfaces. Front loading door with heat-insulation padding is filled with water to provide reliable cooling of the most heat stressed part of the unit.
Convection heating surface is made as bunch of water-cooled fire tubes located in upper part of cylindrical furnace.
Insulated collecting drum of combustion products is equipped with detachable hatches which serve for inspection or maintenance.
Large volume accumulating tank is mounted over combustion chamber. It allows to preserve heated-up water of constant temperature required for uninterrupted heating of buildings.
Auxiliary tank connected to atmosphere is located in upper part of the unit. The tank serves for compensation of thermal expansion of water during heating. Water in it absorbs excess heat during combustion of fuel.
Chimney is located at the rear part of the unit.
Chimney is made of two pipes of smaller and larger sizes and is installed on the principle pipe in pipe. Thus air pillow is created that serves as good insulation of the chimney. Height of the chimney is at least 15m depending on model of the generator.
Combustion process is regulated by change of air feeding fed to straw from the side of loading door. Air is distributed by swinging vane that is controlled depending on oxygen content in exit gases and their temperature. These changes guarantee the necessary amount of air sufficient for combustion of flying particles in upper part of combustion chamber with simultaneous combustion of straw that provides advance of combustion front to furnace floor.
Smoky gases go towards loading door, then upwards into water-cooled fire tubes and after that into discharge header and chimney.
During operation of heat generator volume of exhaust gases is up to 2200 m3/hour, depending on capacity of the unit. Their temperature at exit into the chimney is up to 250ºС depending on stage of combustion of straw bales.
Heat generator is high efficiency coefficient in terms of heat energy production due to efficient combustion of straw.
The heat generator is capable to operate both in manual and automatic mode due to presence of computer unit.
Connection of the heat generator can be done to existing heating network feeding heat both to single building and to complex of buildings depending on its capacity. While existing boilers operating on coal or gas can be used as redundant.
Modern design and use of developed and reliable production technology together with quality assembly of the unit make it:
- highly efficient and cost effective at operation while reliable and durable;
- compliant with existing regulations and standards.
Description of water path, circulation loop
Two water pumps that circulate water inside the unit are installed in the rear part of the heat generator. The first pump circulates water from door of the unit into the water jacket of furnace. The second one circulates water from furnace part into accumulating tank. The pumps operate uninterruptedly irrespective of water temperature in the unit.
Description of fuel and fuel feeding system
Straw of various grain crops is used as fuel.
Feeding of fuel is effected periodically using special loading machinery or manually.
Ways of cleaning smoky gases and removal of ash
The simplest way of ash removal is unloading through the front door by lift tractor equipped with shovel (bucket). Removal of ash also can be performed manually by special scraper that goes with the unit.
It is important to remove all the ash out of the furnace and check so that no damp ash remains. Damp ash is chemically active and can cause corrosion of the heat generator.
Usually ash has to be quite dry but if loaded into the unit straw is damp then it is desirable to remove ash after several loads. Amount of ash changes depending on various types of straw but usually ash is removed after each tenth load.
Fire tubes must be cleaned by brush that goes with the heat generator. Tubes must be always dry. Combustion of one normal straw bale is enough to dry fire tubes to the extent of being easily cleanable by brush.
Clean fire tubes better cool smoky gases thus at frequent cleaning fuel consumption is lower. Fire tubes must be cleaned together with removal of ash or as and when necessary but at least ones a week.
WARNING! Untimely cleaning of fire tubes decreases speed of waste gas passing that can lead to explosion of pyrolysis gases in the furnace.