Does the sulfur recovery acid gas combustion furnace require fuel gas during normal operation?
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Does the sulfur recovery acid gas combustion furnace require fuel gas during normal operation? From what I’ve seen, it needs fuel gas only at startup; it doesn’t require it during normal operation. I’ve seen in forums cases where the furnace temperature was adjusted by controlling the flow rate of the fuel gas – is this part of normal production? Could this lead to the formation of black sulfur?
This isn’t considered normal production, but there’s nothing that can be done about it. We can’t just use a flare to burn it just because NH3 can’t be burned in the sulfur production furnace! As long as the air distribution is appropriate, no black sulfur will be produced; in addition, we have online analysis instruments for monitoring, as well as the eyes of the operators on site.
The combustion furnace requires the use of fuel gas under the following conditions: first, when the concentration of acidic gases is low (e.g., below 30%), the normal furnace temperature is not sufficient, and burning gas is used to raise the temperature. Second is ammonia burning in the device; when other methods cannot achieve the required temperature for ammonia burning, it is usually necessary to burn gas to raise the temperature. Third, although the concentration of acidic gases is high (or ammonia is not burned), the operating load is low; in such cases, gas must also be burned as a fuel. Of course, burning gas may result in the formation of black sulfur or cause the catalyst to become inactive, but as long as the analyzer is functioning properly, the gas composition is kept stable, and the appropriate air supply amount is calculated, it is entirely possible to ensure the steady operation of the device while using gas as a fuel.
To prevent the formation of black sulfur, adding steam can help avoid the creation of carbon black
The answer for 3 is correct, but isn’t 30% a bit high? I’ve seen cases where the concentration was only 23%. According to Hefeng Company, H2S concentrations of 25% or higher allow for proper combustion without the need for any additional fuels, though they use pure oxygen in their processes. So whether to add fuel or not still needs to be determined through heat balance calculations. Additionally: Preheating the acidic gases, and using pure oxygen or oxygen-enriched air, can increase the temperature inside the furnace to a certain extent; in some cases, there is no need for additional fuel mixing.
Sometimes, an improper design of the burner results in the need to keep the fuel gas supply on throughout operation. I know a manufacturer that specializes in producing burners for acidic gases: Luoyang Ruichang Petrochemical Equipment Co., Ltd. The performance of these burners in the ammonia treatment processes at Lijin Refinery is excellent; you might want to get in touch with them!
Friend on the fourth floor: Adding steam to the vapor combustion furnace should lower the temperature. Remember that when the temperature of the combustion furnace rises too high, steam can be introduced; since steam has a high specific heat capacity, it will help to reduce the temperature.
Generally, when the hydrogen sulfide concentration is below 20%, we use fuel gas (liquid nitrogen to treat the exhaust gases) to assist in combustion; the use of fuel gas usually does not result in the formation of black sulfur, whereas the use of liquefied gas easily leads to the formation of black sulfur. Furthermore, the acidic gas components in refineries and natural gas plants are more complex, requiring higher combustion temperatures, whereas those in coal chemical plants are much simpler, and normal combustion conditions are usually sufficient.
It depends on the concentration of your acidic gas; if it’s not enough, fuel gas needs to be burned
Yes, it’s generally above 25%; normal operation doesn’t require additional fuel gas, but driving does require fuel gas
Current data indicate that the recovery of low-concentration hydrogen sulfide (with a volume fraction of less than 25%) can be achieved without using a combustion furnace.
Our sulfur recovery system is equipped with fuel gas; its concentration is low, generally not exceeding 20%, and at times it’s as low as 13%, with an average of 15%. The fuel gas is used to raise the temperature. When the concentration of hydrogen sulfide is low, the concentration of carbon dioxide increases, which in turn lowers the temperature of the furnace. The main purpose is to increase the temperature, and as long as the air ratio is appropriate, black sulfur will not be produced. We are still in the exploratory stage regarding sulfur recovery; if there are experts among you, please add me as a friend so that you can give me some guidance: handshake :handshake :handshake :handshake
If possible, natural gas is the preferred fuel gas for supplementation, mainly because its composition is relatively pure and the air mixing can be easily calculated. Due to the complex and frequently changing composition of refinery gases, it is somewhat difficult to control the air supply. But even with additional gas, as long as it is properly controlled, the problem of black sulfur can be completely avoided.
This issue should be analyzed in this way through discussion; regarding whether to use fuel gas, it should be considered from the following three aspects: 1. For sulfur production furnaces, no fuel gas is required when the furnace temperature is above 900 degrees. Normal production is possible. 2. If it is less than 900 degrees, and no other methods are available, fuel gas can be used to raise the temperature. However, the concentration of the fuel gas cannot be increased indefinitely; it is generally kept at 5%, with the temperature rising by 20 degrees for every 1% increase. 3. Increasing the fuel gas has little effect on ammonia combustion, unless residence time is taken into account in the original design
What was said on the 4th floor is incorrect; in the Claus section of the sulfur processing unit, it’s best to avoid any presence of water. Otherwise, everyone knows what happens when water reacts with sulfur dioxide!
What was said on the 4th floor is correct; in the absence of accurate empirical values for the air-to-gas ratio, we can determine the amount of steam to be used based on the quantity of fuel gas, and by adding a certain amount of steam, we can remove carbon black. I’ll ask the person upstairs: isn’t any water vapor produced by the combustion furnace during normal operation? Obviously, water vapor is present, but sulfurous acid vapor will only cause corrosion to the furnace walls when the temperature is below the dew point; it is only in the presence of a liquid phase that sulfurous acid ionizes to produce H+, thereby causing acid corrosion.
During the shutdown for sulfur blowing, it is acceptable to use steam to regulate the temperature and prevent carbon deposition in order to avoid overheating of the furnace due to fuel gas combustion. However, during normal production, if fuel gas is burned in combination to raise the temperature of the reactor, it is best not to introduce steam at this time. Because introducing steam not only prevents carbon deposition but also lowers the temperature.
To burn ammonia, the furnace temperature must be at least 1250 degrees; when the amount of acidic gas is insufficient or its concentration is too low, gas must be added to raise the furnace temperature. As long as the operator is skilled, the air distribution can be adjusted properly to prevent black sulfur from forming.
1. Under normal circumstances, it is not necessary to use gas; the temperature needs to be maintained above 1200 degrees in order to reach the temperature required for ammonia synthesis. 2. If the load on the device is too low and the desired temperature cannot be achieved, ammonia synthesis will not be successful. In such cases, gas must be used to raise the temperature of the furnace and prevent blockages in the system. It is necessary to calculate how much gas is needed in order to avoid carbon deposition and the formation of black sulfur. 3. Hydrogen is the best choice, as it has a high heat value and does not produce black sulfur. However, whether it is gas or hydrogen, their use will have some negative impact on the conversion rate of sulfur. This is all inevitable. 4. The gas from many enterprises is rich in hydrogen, making it suitable for mixing with acidic gas and feeding it into the furnace to raise the furnace temperature. This post was last edited by adsl121 on 2009-3-24 00:13]
Most of the feed components contain water, but water generally enters the furnace in gaseous form; otherwise it would have been separated in the liquid removal tank before entering the plant! Additionally, water vapor reacts with the hydrocarbons in acidic gases in a water-gas reaction to produce hydrogen and carbon monoxide. The actual operating conditions here also confirm the existence of this theory – the hydrogen consumption is significantly lower than the designed value!