Help: Design of heating and cooling systems for heat transfer oil systems

This post was last edited by hxylt on 2011-6-6 22:52. The design of hot oil and cold oil systems is complicated; generally, a separate hot oil system and a separate cold oil system are installed to allow switching between them； The hot oil system is used only for heating, while the cold oil system is used only for cooling. However, the drawback is that thermal energy cannot be utilized effectively; to make use of the existing thermal energy, complicated processes are required, involving connecting the system to be heated with the system that needs to be cooled in series. It may be quite troublesome in terms of both engineering design and operation. Who can offer some good relevant techniques for everyone to learn from? In a polycrystalline silicon oil system project I designed recently, the hot oil system and the cold oil system are connected in series. The cold oil is pumped to the reduction furnace for heating, after which it returns to the hot oil tank; from there it is pumped to the locations where it is used. The cooled oil (with a relatively lower temperature) then returns to the cold oil tank, starting a new cycle. However, the drawback of this system is that it cannot provide a large temperature rise and cooling temperature. The temperature difference across the entire oil system is about 20 degrees.

I’ve also encountered such problems, which are difficult to solve. Looking forward to it.

What was said on the 2nd floor is very accurate – hot and cold oil systems are indeed complicated. Taking the example given by the poster, there are two reaction vessels, A and B; when vessel A is at 300°C, vessel B is at 100°C. In this case, it is necessary to cool vessel A and heat vessel B. To achieve this, a circulation pump along with at least four valves can be used to circulate heat transfer oil as a medium for storing heat and cooling energy between the two vessels. The ideal situation is for both vessels A and B to reach a temperature of (300 + 100)/2 = 200°C; at that point, the circulation process ends. Vessel B, which is above 200°C, needs to be heated back to 300°C using hot oil, while vessel A, which is below 200°C, needs to be cooled further using cooler water or cold oil. . There are quite a number of programmable valves involved in the switching of the entire system. The heat storage cycle mentioned earlier requires 4 valves, and it is essential that the AB systems be able to switch between these 4 valves. If cooling water and hot oil cycles are added as well, the whole process becomes extremely complex, making operation very troublesome and downright exhausting. A feasible approach is to cool the hot oil using air cooling, or to use an air-cooled chiller to cool the hot oil, thereby eliminating the need for cooling water and replacing it with cold oil; this would result in lower energy consumption compared to your current system.

This post was last edited by flootherm on 2011-6-29 22:03. In the same heat transfer oil system, it is possible to have multiple users with different temperatures (a difference of 1 to 200 degrees is also feasible)； It is also possible to achieve both heating and cooling. How can this be achieved? Simply put, it involves adding a small subsystem to a large heat transfer oil system, which includes a small pump and a temperature control valve! You can contact me by E-MAIL.

Hehe, a system can only control one reactor; it’s not possible to have two reactors with one being heated and the other cooled simultaneously. Unless you create two separate closed-loop cycles for heating and cooling the heat transfer oil, the problem of oil mixing will still exist, and thermal energy cannot be utilized effectively. What was described upstairs as being so complicated is actually just a secondary circulation system for heat transfer oil; this system enables very good temperature control, allowing the temperature to be maintained within ±1℃ of the set value. However, it is used in constant-temperature systems; the principle is that hot oil is added when the temperature drops. There is no heating or cooling system, so the operating temperature cannot be adjusted, and it cannot meet the requirements for raising or lowering the temperature of the tank. The heating of the heat transfer oil can be done using heat transfer oil itself, but cooling is only possible with circulating water. If you want to use cold oil for replacement, how can that be achieved? And will the temperature meet the requirements of the temperature of your other reactor? Either create three systems with a temperature difference of 50–100°C each: 0–100, 100–200, and 200–300. Once the temperature in the reactor at 300°C drops, it returns to the 100–200 system; the fluid from this system then preheats another reactor, after which its temperature drops again and it returns to the 0–100 system. The fluid from the 0–100 system is then cooled in the reactor that needs to be brought to 100–200°C, and after heating up it is sent back to the 100–200 system, from where it is further cooled in the 200–300 system. This approach allows for maximum utilization of thermal energy, but I imagine it would overwhelm the operators. It’s annoying. Not recommended for use.

Reply to 4# zpg: Using a chiller for cooling must result in higher energy consumption, right? Circulating water is definitely the cheapest option. At such high temperatures, if circulating water is used for cooling, the cooled water can be discharged directly, losing the purpose of being sent back to the circulation tank.

:Q: I’ve read the posts from many brothers upstairs, but I can’t see any unified opinion.