I have a question regarding the use of gas-fired heat transfer oil furnaces to heat reaction vessels
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This is my first time working with a heat transfer oil furnace. The material inside the reactor needs to be raised to a certain temperature and held there for an extended period of time. During this holding phase, the heat load is very low, so the reactor hardly requires any heat. The temperature of the oil coming out of the furnace and the temperature of the oil returning to it are not very different. If heating continues during this phase, it will inevitably lead to an increase in the temperature of the oil coming out of the furnace. How is then the temperature of the oil exiting the furnace controlled during the holding phase?
During the heat retention phase, the heat transfer oil circulates in a loop (bypass); the reaction vessel regulates the amount of oil supplied through the oil inlet valve or oil return valve to maintain the desired temperature. At this time, the oil outlet temperature of the heat transfer oil furnace is regulated by its own circulation system, along with adjustments to the amount of gas supplied and the volume of air flow
Regarding the flame adjustment of the heat transfer oil furnace you mentioned, could it be the case that during the constant temperature phase, the reactor requires less heat? In such a situation, the outlet temperature of the heat transfer oil furnace might be 250 degrees, while the return temperature is 249 degrees – the difference is very small. In this case, even if the flame is reduced, the outlet temperature should still rise, right?
Also, regarding what you mentioned about the oil outlet temperature of the heat transfer oil furnace being regulated by its own circulation system, since this is my first time dealing with such a system, I’m not quite sure how circulation is used for control. Could you please provide detailed information on this?:)
1. Is there a water-cooling coil inside the reactor, and can its temperature also be controlled? 2. Can the heat transfer oil be cooled and its temperature controlled before being fed into the reaction vessel? 3. Is it allowed for the heat transfer oil to be mixed with the heat transfer oil in the bypass circuit before entering the reactor for cooling? And then return to the heat transfer oil furnace and use a bypass to cut it off?
There is no cooling system inside the reaction vessels; it seems that not all of our reaction vessels are kept at a constant temperature at the same time – some are heating up while others remain at their current temperature. Therefore, we are concerned that the temperature of the oil coming from the heat transfer oil furnace might become too high
There is a bypass valve on the line in charge; when the reaction vessel is not being heated, all the heat transfer oil flows through the bypass, thereby allowing for control
I understand what you mean – the heat transfer oil is used in a large circulation system. During the insulation phase, our heat demand is very low; for example, if the outlet temperature is 250 degrees, the return temperature might be around 248 degrees. As a result, even with the lowest possible flame and gas flow rates, the outlet temperature can still exceed 250 degrees. When the flame is turned off, the temperature drops again. I was wondering about this situation, as frequent turning on and off of the flame will surely have an impact on the system
It’s simple: shut down the boiler for a while but keep the circulation pump running, and be careful not to let the liquid level in the expansion tank reach a point where boiling occurs!
The hot oil furnace operates intermittently: a temperature range is set, ignition occurs when the temperature reaches the lower limit, and the furnace stops operating when it reaches the upper limit.
Isn’t there automatic control for constant temperature and pressure now?