The Herbst Gasmiser – Simple, safe and convenient
- It eliminates creosote build up and the hazards of chimney fires.
- It burns peat cleanly
- Significantly reducing smoke emissions.
- It can efficiently burn hard wood or soft wood chips with a moisture content up to 50% and many other biomass fuels and industrial wastes.
- It can be fitted to most new or existing boilers
How The Herbst Gasmiser Works
The Herbst Gasmiser employs a simple, well proven technology to convert solid fuel to useful energy. The system is based on an innovative combustion process that releases the total energy available in solid fuels.
The Herbst Gasmiser is designed to burn various types of low grade fuels at high thermal efficiency and low pollution rates.
Combustion of the fuel is divided into two stages, gasification and combustion. In the first stage preheated primary combustion air is introduced and at this point the fuel is decomposed to hot gas and glowing carbon. The reaction between oxygen in the air and carbon in the fuel supplies sufficient heat for a second reaction. The second reaction produces carbon monoxide, a major combustible component of the producer gas. The steam, including hydrogen and a small quantity of methane.
In the following stage the gas is drawn into the combustion tunnel and secondary combustion air introduced. Ignition starts in this zone and the gas is completely burned in the combustion tunnel and the combustion chamber of the boiler or air heater.
The heat output is controlled by regulating the downward flow of fuel in the hopper and by adjustment of the primary and secondary combustion air dampers. With the Herbst Gasmiser this is fully automated.
Almost any solid fuel can be used, provided it meets the following broad guidelines:
- The individual particle size is between that of a prime fit and a 50mm (2 inch) cube.
- The calorific valve, as determined on a Par Bomb (ASTM d20 15) is greater than 10.5 MJ/kg as delivered to the Gasmiser.
- Ash fusion point is above 1100oC in a reducing atmosphere.
- For efficient operation and maximum plant life it is generally recommended that the fuel moisture content should not exceed 35% net weight.
- The fuel is available in the required quantity throughout the economic life of the installation. (The fuel can be any combination of materials meeting the guidelines).
Construction of the Herbst Gasmiser.
The plant is of modular construction that can be adapted to various conditions and specifications. The three main components are:
GASIFIER, FUEL HOPPER AND COMBUSTION TUNNEL.
The Gasifier has been manufactured from a high rate fire proof mass and is insulated with a rigid mineral wood board. In the base of the Gasifier is an ash container and above this the grate and grate bears. The grate height can be adjusted by a control lever outside the casting. The grate is designed especially for the gasifier and the particular fuel used. It is made from a special cast iron. Located above the grate is the most important component of the Gasifier, the reactor.
The reactor and it’s supports are made from a high chrome alloy, especially developed for this application. In the front there is a well sealed cleaning door which also contains the control damper for preheated primary combustion air.
The Fuel Hopper.
The Fuel Hopper is a gas tight construction of 1mm, mild or stainless steel (dependent on fuel used). The loading door is sealed with a heat resistant strip.
The Combustion Tunnel.
The Combustion Tunnel is made from the same fireproof mass as the Gasifier and is fully insulated.
Operation of the Herbst Gasmiser.
The Herbst Gasmiser is easy to install and simple to operate. The fuel is gravity fed to the Gasifier and the heat output control is automatic. An occasional visit to replenish the hopper and remove the ash is all that is required. In most cases this would be once a day or less.
Generally the existing chimney is suitable. However in some cases the chimney must be up graded or changed. The following graph gives an indication of chimney sizes for various Boiler/Herbst Gasmiser combinations.
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