Is it appropriate to use superheated steam for heating at a reaction temperature of 320°?
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This post was last edited by Luobu on 2019-1-3 at 10:41. Is it appropriate to use superheated steam for heating at a reaction temperature of 320°? What precautions should be taken? Additionally, by how much is the heat transfer coefficient of superheated steam lower compared to that of heat transfer oil?
Superheated steam has a poor heating effect; when saturated steam is used for heating, it liquefies into water and undergoes a phase change that releases a large amount of heat, and it is this latent heat that is primarily utilized for heating. Superheated steam does not liquefy easily when used for heating; only a small amount of sensible heat can be utilized, so its effectiveness is very poor. Electric heating should be used in this case. Induction heating is more energy-efficient but requires certain conditions for use, while resistance heating is simple to implement. Heating with heat transfer oil is also an option, but a circulation system is needed; it can be used at temperatures below 400°C
Using electric heating at over 300 degrees is relatively stable
It’s not suitable; consider heat transfer oil instead.
Actually, it also depends on the specific process; certain processes do not allow the use of heat transfer oil
The reaction temperature is 320°; the temperature of the heating medium must be 30–50°C higher than that of the material being heated, so the heating medium needs to reach at least 350°C. Using superheated steam for heating is not practical. The reason is that the pressure of saturated steam at 301°C has reached 64 MPa, making equipment manufacturing quite difficult and costly. It is recommended to use heat transfer oil T66 (hydrogenated triphenyl) as the heating medium; this oil can withstand high temperatures of up to nearly 400°C and has a low saturated vapor pressure. Other high-temperature resistant heat transfer oils with low saturated vapor pressures can also be chosen. If the reactor is small, electric heating can be used. For your reference
In the edible oil industry where I used to work, there was a process that required heating to 250 degrees, using steam for heating. The use of heat transfer oil for heating is prohibited in the food industry, to prevent the heat transfer oil from mixing with food in the event of a perforation in the heat exchanger, as the consequences would be disastrous.
It depends on the physical properties of the substance and the requirements regarding temperature control. For example, in the production of hydrogen through methanol cracking, heat transfer oil is used, while we employ superheated steam at 350 degrees; therefore, no generalization can be made
I have a gentle question: which substance has a saturated vapor pressure of 64 MPa at 301 degrees? The saturated vapor pressure of water at 301 degrees is only 8.8 MPa
Choose between electric heating and heat transfer oil; just calculate which one has lower energy consumption. Steam is not applicable