Reasons for carbon deposition above the burner of the heating furnace
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It’s a furnace that uses fuel gas and requires daily liquid removal; currently, the furnace is not functioning properly – there are large fluctuations in both the outlet temperature and oxygen level. The furnace tubes have turned black, and carbon buildup has formed above many nozzles. What are some good solutions and suggestions? Experience would be appreciated; thank you. This post was last edited by chengkang on 2009-3-5 12:19]
1. Solve the liquid-containing issue at its source. 2. Use steam for heating the fuel gas pipeline and put it into operation. 3. Improve liquid removal in the fuel gas buffer tank, and discontinue use of the steam heating coil (except in northern facilities during winter). 4. The burner at the fuel gas outlet of the heating furnace must be ignited.
Here, liquefied gas sometimes contains liquid droplets; it’s necessary to remove these drops several times during a shift. However, no coking has been observed in the burners. It’s likely that in your area the liquid droplets aren’t removed frequently enough. By increasing the frequency of such removals and improving the quality of the liquefied gas, things might get better
The main issue is that there are too many heavy hydrocarbons in the gas; it’s possible to analyze its composition. In typical burner designs, the content of C3 and higher hydrocarbons should not exceed 2.5%, so it’s important to examine the composition of the gas
Controlling the content of components above C3 in the dry gas in the upstream units, with a recommended level not exceeding 4%, should help to alleviate coking in the burners of the heating furnaces；
If misting air is added, coking occurs
Analyze the composition of the fuel gas; the content of components with a molecular weight of C3 or higher in the dry gas should not exceed 3%
Gas carrying liquid and an excessive amount of hydrocarbons in the gas are the main causes of coking. Fuel gas is a systemic issue that needs to be addressed at its source; individual units alone are not effective in solving this problem! It is recommended to implement management across the entire plant!
Regardless of the components, it is caused by incomplete combustion; a suitable burner can always be found
What do you mean by solving it at the source? Is it too late to remove the buffer tube? And why stop the heating coil of the buffer tube? Is it to allow what needs to be condensed to do so? The other two points have been met
Carbon buildup in the fuel injectors is mainly caused by the following factors: 1. The fuel is too heavy and has high viscosity, resulting in inadequate atomization. . . 2. The pressure of the atomized steam is insufficient; it is not superheated steam. . . 3. The fuel temperature is too high. . . 4. Weak wind leads to incomplete combustion. . . 5. The atomization method needs improvement. . . 6. The burner model does not match the fuel oil. . . :lol
If the gas burns and the furnace tubes turn black, it indicates that the air flow is insufficient; the flame becomes unstable. Try to balance the pressure in the gas tank, adjust the air flow properly, and control the negative pressure as well
I’m also extremely annoyed by this issue. The required pressure difference before and after reinstalling the flame arrester is no more than 0.06 MPa, while for pre-hydrogenation it should be no more than 0.08 MPa. We often have to switch the flame arrester due to excessive pressure differences, and then carry out purging； Is the dark, sticky substance inside the pipes carbon buildup? How does it form, since there’s no combustion involved? What exactly is it? Please explain, haha
Replying to the person above: That dark, sticky substance inside the pipes is definitely not carbon deposit; it’s probably tar. Is the temperature of the gas very high, or is the heating system set at a high level? It’s the residue left after some oils evaporate, and it serves as a precursor to carbon
1. Whether combustion is complete or not. 2. The dry gas is not dry, and its composition does not meet the requirements