Control of furnace temperature in heat transfer oil furnaces
Thread Content
Recently, abnormalities have occurred frequently in the heat transfer oil furnace, with the main issue being excessively high furnace temperatures. Currently, the furnace temperature is between 850–860 degrees Celsius, while the temperature at the furnace outlet remains around 264 degrees Celsius. When the upstream unit increases its production volume, the furnace temperature rises above 900 degrees Celsius. Current inspection findings are as follows: 1. The open flash point of the heat transfer oil is below the required value, and the levels of residue and acid value are high. 2. The temperature measurement point for the furnace temperature is located at the top of the furnace (in the convection chamber); originally, coal was used as fuel, but it has since been switched to a mixture of gas (natural gas, purge gas). Previously, there were abnormalities in the temperature readings at the furnace inlet; these issues have been resolved after consulting with the instrumentation team. 3. An examination of the process adjustments was carried out; the system operates in a closed-loop cycle. However, there is a temperature difference of over 10 degrees Celsius between the oil returning from the upstream unit and the oil entering the furnace, while the temperature difference from the furnace outlet to the upstream unit is only 1 degree Celsius. 4. The equipment has been in operation for a long period without any maintenance for two years, so it’s possible that carbon buildup and ash accumulation on the furnace walls exist, though the extent of this issue is unknown. I would appreciate any suggestions you might have
【The open flash point of the heat transfer oil is below the **required value, and the carbon residue and acid value are on the high side】, which indicates that the quality of the heat transfer oil has declined, with decomposition and coking occurring. 【An inspection was carried out on the process adjustments; the flow is in a closed-loop cycle. However, the temperature difference (loss) from the oil returning from the upstream unit to the furnace is over 10 degrees Celsius, while the temperature difference (loss) from the furnace outlet to the upstream unit is only 1 degree Celsius.】This is hard to understand, aside from the difference in insulation effectiveness.
Is it a big shot pulling a small cart? The boiler generates heat, but the process side is unable to consume it, resulting in a too small temperature difference and severe carbonization of the heat transfer oil. It is recommended to reduce the temperature setting and the proportional control ratio to control combustion.
Please tell me what size of equipment is suitable for what size of furnace. The outlet temperature of 268, with a furnace temperature of 900 – that’s a bit scary. If it’s convenient, you can contact them to send an engineer to the site; my phone number is in my profile picture. It seems that there is a lot of dust accumulated in the chamber, which prevents heat from passing through and results in heat loss; otherwise, the outlet temperature of the high-temperature heating oil at 900 degrees would not be around 260 degrees. It is recommended to lower the temperature to prevent the furnace from being burned through and causing safety accidents.
Additionally, the difference between the outlet temperature and the loop temperature should be low, normally around 20–30 degrees. If the temperature is only 10 degrees now, and if the equipment heats up slowly, it indicates that severe coking in the pipelines has occurred, blocking heat flow and preventing the equipment from heating up; this results in an abnormal difference between the inlet and outlet temperatures. Additionally, if the flash point of the heat transfer oil, as measured at the testing port, is already low compared to the standard of 100 degrees, use should be stopped immediately to avoid fires.