Help with converting the usage of heat transfer oil and natural gas!

To maintain a constant temperature, it is only necessary to replenish the heat lost through heat dissipation. In an insulated environment (with good insulation and minimal heat loss), whether the temperature is 290 degrees or 280 degrees, no additional heating is required. But this does not exist in reality; the amount of heat dissipation is mainly related to the surrounding environment and the insulation properties of the container. It is impossible to make any calculations based only on these parameters. If there is a consumption of 280 degrees, a simple calculation can be done: (290 – ambient temperature) / (280 – ambient temperature) * 280, to determine the natural gas consumption

There shouldn’t be much difference; it’s just a rough estimate. After all, it’s merely a matter of comparing differences. Let’s first estimate the difference in temperature on the outer surface of the insulation. Assuming that at 290°, the temperature on the outer surface of the insulation is 40° (I’m not familiar with the relevant insulation standards, but there must be some regulations), and the ambient temperature is 30°, then when the oil temperature is 280°, the temperature on the outer surface should be about 0.4° lower. Assuming the total area of the insulation is 100 square meters, and considering air convection (after all, it’s not like there’s strong wind blowing on it all the time), let’s use a heat transfer coefficient of 50 W/m2/°C. In that case, an additional 2 kW of heat will be lost. The calorific value of natural gas is 100 kwh/m3, so an additional 0.5 cubic meters of natural gas will be consumed per day. I’m doing this just as a calculation; if you use the method mentioned above, you’ll see that whether the ambient temperature is 30° or 10°, the value of (290 – t)/(280 – t) is very close to 1, so there won’t be much difference. Not enough natural gas will be consumed that it can even be detected

The temperature difference is too small to notice.

It depends on the system’s insulation measures. How much natural gas was used in the past?

If 100 tons of material are heated per day, from room temperature to 200 degrees, and the heat transfer oil is raised from 230 degrees to 250 degrees, how much more energy might be consumed?

It’s also that much. The heat load remains unchanged, the amount of heat applied stays the same; the material being heated still reaches 200 degrees. Its heat loss also remains unchanged – the only difference lies in the heat loss of the heat transfer oil itself. In essence, there’s basically no difference

Strictly speaking, there is also a slight change in the temperature of the furnace exhaust gases, which leads to increased consumption. At this temperature, there’s no significant difference

The changes in natural gas consumption caused by variations in surface temperature differences are calculated using the insulation calculation formula

After carefully examining all the answers from above, for a 40-ton boiler, an amount of heat of 600,000 kilocalories x 40 = 24 million kilocalories is required (0.7 x 40 MW). The lower heating value of natural gas is taken as 8500 (35.53 MJ/Nm3); with an efficiency factor, the boiler’s capacity is approximately 3000 m3/h. Since this is on a daily basis, this figure needs to be multiplied by 24, resulting in around 72,000 cubic meters per day. As for heat transfer oil, no parameters have been provided yet – and this is actually an important issue. Alkyl naphthalene-type heat transfer oils can only operate at temperatures up to 280°C; alkyl biphenyl-type heat transfer oils can operate below 330°C; biphenyl and biphenyl ether low-melting mixture-type heat transfer oils can operate up to 400°C. For ordinary mineral-based heat transfer oils, a separate test report is required. In other words, without taking into account the heat transfer oil itself. The difference between raising the temperature to 290°C and 280°C is basically just a 10-degree difference. (The ambient temperature is assumed to be 0.) The simplest method is interpolation. 72000*10/280 is approximately 2500 m3/day. This relates to knowledge about heat carrier boilers; those in the pressure vessel industry generally don’t understand the concept of a 40-ton heat transfer oil boiler. Of course, this is an estimated approximate value; the actual figure will depend on the parameters of your device. There are also many other influencing factors, so it’s impossible to provide an exact figure.