The spreader firing principle is the most widely accepted, proven and user friendly means of burning biomass fuels. Sized fuel is metered to a series of distribution devices which spread it uniformly over the stoker grate surface.
Fine particles of fuel are rapidly burned in suspension assisted by carefully designed overfire air turbulence systems. Coarser, heavier fuel particles are spread evenly on the grate forming a thin, fast-burning fuel bed. The combination of suspension and the fast-burning bed makes this method of firing extremely responsive to load demand.
Minimum fuel supply on the grate and automatic ash discharge reduce furnace upsets and provide better control of emissions. The high burning rates permissible with the spreader stoker concept minimize the grate area required--a prime consideration in retrofit applications.
Detroit Hydrograte Stoker Features:
Reliability Under Varying Load Conditions:
The Detroit Hydrograte stoker combines advanced spreader stoker technology with automatic ash discharge and water-cooled grates. This stoker handles a variety of high moisture, low ash fuels over a broad range of steaming capacities with high reliability. Ideal for High Moisture Biomass Fuels Because the Hydrograte stoker is water-cooled, it can be fired based on combustion conditions without regard to cooling air requirements. This unique design makes it ideal for burning biomass fuels which are high in moisture and low in ash. The higher combustion air temperature needed to burn high moisture fuel can be maintained without damaging the grates.
Ideal for Low Ash Fuels:
No ash cover is needed to protect the grate. This makes the Hydrograte stoker ideal for burning low ash waste fuels. Higher Efficiency Water-cooling also means that no cooling air is required during periods of auxiliary fuel firing. This increases efficiency and reduces emissions.
Lower Emissions:
The ability to minimize undergrate airflow reduces excess air. This ensures the most effective use of overfire air which optimizes emission control and combustion efficiency. Higher percentages of overfire air are utilized for effective staged combustion--an important factor in controlling nitrous oxide emissions.
Lower Maintenance Costs:
Simple design with a minimum of moving parts reduces down time and maintenance costs.
Continuous Operation:
Because positive automatic ash discharge eliminates shutdowns to clean grates, the cost of auxiliary fuel to maintain load during grate cleaning is eliminated.
Horizontal Spreader Stoker Retrofit Applications:
The Detroit Hydrograte® stoker can be arranged with a horizontal grate surface. In addition to the benefits of this advanced water-cooled design, the need for boiler modification is minimized in retrofit applications where space limitations exist. Compatibility with auxiliary or alternate fuels is the same as with the inclined grate. Additionally, it is compatible with conventional power boiler designs in terms of grate heat releases making this grate very attractive for retrofitting in existing power boilers.
Reduced Installation Time:
This water-cooled vibrating grate offers significant advantages in installation time when compared with other stokers. The Detroit Hydrograte® stoker is shop-assembled in large modules which are limited in size only by shipping considerations. This means shorter installation schedules on new units and quicker turnaround times on retrofits. In many cases, portions of the existing overfire air system can be incorporated into an upgrade as well.
Other Benefits:
Automatic ash discharge permits continuous operation without shutdowns to clean grates.
Few moving parts means reduced down time and maintenance costs.
No lubrication problems since the vibrating has neither bearings nor shafting in the undergrate environment.
Ability to minimize undergrate air lowers excess air and permits maximum use of overfire air for emission control and optimum combustion.
Effective air seals between stationary and moving surfaces allow greater air control.
Fine particles of fuel are rapidly burned in suspension assisted by carefully designed overfire air turbulence systems. Coarser, heavier fuel particles are spread evenly on the grate forming a thin, fast-burning fuel bed. The combination of suspension and the fast-burning bed makes this method of firing extremely responsive to load demand.
Minimum fuel supply on the grate and automatic ash discharge reduce furnace upsets and provide better control of emissions. The high burning rates permissible with the spreader stoker concept minimize the grate area required--a prime consideration in retrofit applications.
Detroit Hydrograte Stoker Features:
Reliability Under Varying Load Conditions:
The Detroit Hydrograte stoker combines advanced spreader stoker technology with automatic ash discharge and water-cooled grates. This stoker handles a variety of high moisture, low ash fuels over a broad range of steaming capacities with high reliability. Ideal for High Moisture Biomass Fuels Because the Hydrograte stoker is water-cooled, it can be fired based on combustion conditions without regard to cooling air requirements. This unique design makes it ideal for burning biomass fuels which are high in moisture and low in ash. The higher combustion air temperature needed to burn high moisture fuel can be maintained without damaging the grates.
Ideal for Low Ash Fuels:
No ash cover is needed to protect the grate. This makes the Hydrograte stoker ideal for burning low ash waste fuels. Higher Efficiency Water-cooling also means that no cooling air is required during periods of auxiliary fuel firing. This increases efficiency and reduces emissions.
Lower Emissions:
The ability to minimize undergrate airflow reduces excess air. This ensures the most effective use of overfire air which optimizes emission control and combustion efficiency. Higher percentages of overfire air are utilized for effective staged combustion--an important factor in controlling nitrous oxide emissions.
Lower Maintenance Costs:
Simple design with a minimum of moving parts reduces down time and maintenance costs.
Continuous Operation:
Because positive automatic ash discharge eliminates shutdowns to clean grates, the cost of auxiliary fuel to maintain load during grate cleaning is eliminated.
Horizontal Spreader Stoker Retrofit Applications:
The Detroit Hydrograte® stoker can be arranged with a horizontal grate surface. In addition to the benefits of this advanced water-cooled design, the need for boiler modification is minimized in retrofit applications where space limitations exist. Compatibility with auxiliary or alternate fuels is the same as with the inclined grate. Additionally, it is compatible with conventional power boiler designs in terms of grate heat releases making this grate very attractive for retrofitting in existing power boilers.
Reduced Installation Time:
This water-cooled vibrating grate offers significant advantages in installation time when compared with other stokers. The Detroit Hydrograte® stoker is shop-assembled in large modules which are limited in size only by shipping considerations. This means shorter installation schedules on new units and quicker turnaround times on retrofits. In many cases, portions of the existing overfire air system can be incorporated into an upgrade as well.
Other Benefits:
Automatic ash discharge permits continuous operation without shutdowns to clean grates.
Few moving parts means reduced down time and maintenance costs.
No lubrication problems since the vibrating has neither bearings nor shafting in the undergrate environment.
Ability to minimize undergrate air lowers excess air and permits maximum use of overfire air for emission control and optimum combustion.
Effective air seals between stationary and moving surfaces allow greater air control.
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