Can the frequency of the circulation pump in a heat transfer oil furnace be automatically controlled based on the heating equipment in use?
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Frequency conversion renovation of coal-fired heat transfer oil boilers: Currently, the outlet oil temperature is controlled by adjusting the frequency of the induced draft fan’s frequency converter. I am not very familiar with this process, so I would like to ask if the frequency of the circulation pump’s frequency converter is set manually. When the heat demand from the heating equipment increases, the inlet oil temperature drops; in such cases, can the frequency of the circulation pump be automatically controlled based on the temperature difference between the inlet and outlet oils? It might be possible to set upper and lower limits for the output saturation to prevent the frequency from dropping too low. Or is the inlet oil temperature only used for alarm purposes? If that’s the case, wouldn’t it take a long time for the induced draft fan to respond to an increase in heat demand? I’m a beginner; thank you~~
Changes in the heat load applied by thermal equipment can only be adjusted through the flow rate of the heat transfer oil and the temperature difference between its inlet and outlet. 1. In the design, the flow rate of the heat transfer oil is constant (no variable frequency drive for the circulation pump). The frequency converter of the exhaust fan is proportional to the heating load of the equipment that uses heat; in other words, it is inversely proportional to the temperature of the heat transfer oil at the inlet. The flow rate of the heat transfer oil is around 2 m/s. 2. If a frequency converter is used for the circulation pump as requested by the building owner, the system is likely designed to maintain a constant temperature difference between the inlet and outlet. In this case, the frequency of the circulation pump’s frequency converter is proportional to the heating load of the equipment that uses heat, while the frequency of the exhaust fan’s frequency converter is proportional to the frequency of the circulation pump’s frequency converter. 3. If the temperature difference between the inlet and outlet is not constant, nor is the flow rate of the heat transfer oil constant, then the regulation is fastest when the product of the frequency converter for the circulation pump and that of the frequency converter for the exhaust fan is proportional to the variation in the heating load of the equipment using heat.