Boiler Control Parallel Positioning Methods
The American Society of Mechanical Engineers recognizes two classifications for boilers: heating boilers and power boilers. Power boilers are used in institutional settings. All boilers need effective control mechanisms. One such control mechanism serves to regulate steam flow into the boiler system. Does this Spark an idea?
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Boiler Control System
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A boiler control system regulates a boiler so to produce a certain steam flow safely and efficiently. This control system provides the boiler with the right amounts of air and fuel based on the demand for the steam. The control system should also function to shut down the boiler during times when it detects abnormalities. For instance, it should shut down the boiler in case it detects too much steam. A common method used to control these systems is the generation of a master control signal, using the steam pressure.
Parallel Positioning Methods
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A positioning control mechanism moves to a preset position in response to system needs. A parallel positioning system uses a master control signal to control the boiler system. A parallel positioning system causes a change in both the flow of fuel and air when it wants to make a change in steam flow. When there is a variation in the steam pressure, this affects the fuel input. At the same time, the steam flow controls the combustion air flow.
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Jackshaft Positioning
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The jackshaft method is advantageous for industrial boilers because it helps save costs. In this method of using a jackshaft for parallel positioning, the combustion control mechanism responds to changes in steam pressure. The boiler operator can also control the mechanism with a manual override. The operator calibrates the positions for the fuel and air flow, and the linking of the control, at the time of starting up the system. You could better control the excess air by substituting electric or pneumatic systems for mechanical linkages.
Advanced Systems
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There are more advanced control systems for boiler control. These include systems that control fuel and air pressure based on pressure ratio control. Another such technique involves direct metering of fuel and air. There are also excess air correction systems that perform their function by monitoring flue gas. These more sophisticated systems are more likely to be used in industrial boilers, rather than smaller boilers, because of considerations of cost and maintenance.
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References
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