Heating issue in the jacket of the reaction vessel
Thread Content
This project is a pilot-scale project for a side-line unit, with a scale of 1/200 that of a large industrial plant. Due to its small size, it is necessary to give careful consideration to the significant heat dissipation generated in the reactor due to convection and other factors. A jacket is specifically installed outside the reaction vessel, with hot water intended to be circulated through this jacket to compensate for the heat loss of the reaction vessel during experiments. The internal design of the reactor specifies a reaction temperature of 75 degrees, whereas the temperature of the hot water at the site is around 120 degrees. The internal reaction medium is the polymerization of tetraenoic hydrocarbons and syngas. The issues are as follows: 1. The temperature of the hot water supplied to the jacket is 45 degrees higher than the designed temperature of the reactor. Could this lead to uneven heating within the reactor, thereby causing the actual reaction temperature to deviate from the designed value? This then leads to a series of problems, such as an increase in the vapor evaporation rate inside the reactor and changes in the composition of the vapor phase; as a result, the purpose of the side-stream testing setup under the specified conditions is lost ； 2. After hot water is introduced into the jacket, to prevent the problem mentioned in point 1, is it better to use interlock control for the temperature inside the jacket, or to directly use interlock control for the temperature inside the reactor? Thank you all. . .
Isn’t your reaction an exothermic reaction? Generally, the jacket flow rate should be linked to the internal temperature of the tank. But assume that this reaction neither releases nor absorbs heat, merely maintains temperature, and that the temperature of the jacket is also good.
It is an exothermic reaction; under normal conditions, the heat released is removed using an external cooler. The purpose of installing a jacket now is to prevent such a small device from losing a large amount of heat through convection with the surroundings, thereby affecting the reaction conditions. Or it is necessary to maintain the reaction temperature inside the furnace.
The main concern is that there is a significant difference between the temperature of hot water and the designed reaction temperature inside the reactor; if local temperature variations cause this temperature to rise, it might deviate significantly from the designed reaction temperature
Water at 120 degrees is low-pressure steam. Since your reactor is small and serves only to maintain the reaction temperature, the temperature difference seems a bit large.
The temperature of the hot water at the site is 120 degrees, high enough to be vaporized into steam. As you said, the design temperature is 75 degrees. Generally, the design temperature is 15-30 degrees higher than the normal operating temperature; therefore, the operating temperature inside the reactor should not exceed 60 degrees. A temperature of 15 degrees should be sufficient during heating, so a bath temperature of 75 degrees will do. So the desired temperature of the water supply is generally around 80 degrees; 120 degrees is too high (as it’s not possible to maintain sufficient pressure).
It’s a very small pot; using such hot water, it’s likely difficult to maintain a stable temperature.
Thank you for the reply. 75 degrees is the normal reaction temperature specified in the design; if the temperature of the water bath is 15 degrees higher than this normal value, then around 90 degrees should be sufficient
If the polymerization reaction releases a lot of heat, how can the heat be removed? In this case, only internal coil cooling and external jacket heating are possible. Adjustments are made on-site according to the actual conditions; if the temperature rises, cooling should be carried out promptly. By checking a few more times, it becomes clear what the appropriate temperature difference should be and what flow rate is suitable. I think it’s pretty simple, just a light tap
Why is heat exchange removed through an external cooler? Cool it over there, keep it warm here? Isn’t that a waste of energy?
The polymerization reaction requires heating to be initiated, but once it starts, the reaction becomes intense and releases a large amount of heat; if this heat cannot be removed in time, it can be very dangerous. Therefore, ordinary reaction vessels require heat supply and heat removal.