Can the heat from the flue gas of a heat transfer oil furnace be recovered?
Thread Content
Our plant is an LNG facility; the heat transfer oil furnaces used in the plant operate on natural gas as fuel, with heat transfer oil serving as the heat carrier to supply heat to the production units. However, the flue gases from these furnaces reach temperatures of up to 200 degrees, and around 700 cubic meters of natural gas are burned daily, which seems like a waste. Is it possible to recover this natural gas? What methods exist for that?
The furnace is very small, with a limited capacity, which restricts the space available for recycling.
Add an air preheater! The flue gas temperature should be more than 200 degrees, right?
Add an air preheater! The flue gas temperature should be more than 200 degrees, right? 200 degrees with an air preheater is also not very appropriate; the minimum outlet flue gas temperature should be kept above 150 degrees. If it really is 200 degrees, I believe using an air preheater is not suitable!
Theoretically, any heat can be recovered, but it depends on whether it is worth doing so. One method mentioned by those above is to install an air preheater; however, you only burn 700 cubic meters of natural gas per day, which is a very small scale. With such a small scale, the energy-saving benefits are minimal, and I personally think there’s no need to go through this hassle.
Add an air preheater to control temperature and recover heat
The furnace is not large, so the energy-saving effect is not significant
If an air preheater is added, the flue gas temperature drops below 150 degrees; when the fuel contains sulfur, dew point corrosion will inevitably occur, severely damaging the equipment and chimneys, and not much heat can be recovered either, making it a loss rather than a gain. Such a small stove. The thermal efficiency is not very high from the design stage. Heat loss is something that cannot be avoided.
The only option is to add an air preheater; there are no other energy-saving methods. Moreover, the furnace has a relatively low power level, making it difficult to operate!
The furnace is too small, resulting in very little heat that can be recovered; from an economic perspective, it is not cost-effective to invest in an air preheater. If an air preheater is installed, and the flue gas exit temperature drops to the dew point temperature, dew point corrosion can easily occur!
The correct approach is to install a flue gas heat recovery system; the heat recovered can be used for heating, bathing, and other water heating purposes, without the need to worry about low-temperature S corrosion.
A flue gas temperature of 200 degrees is already quite low; when heat exchange occurs, it can lead to low-temperature corrosion, and it’s likely that the equipment will need to be repaired every year, which is not worth it.