Ammonia burning in sulfur production furnace

It is estimated that ammonia decomposes completely; at temperatures above 1250 degrees, it breaks down into nitrogen and hydrogen. At 700 degrees, decomposition begins, and at 1000 degrees only 4.9% of it decomposes. ”If ammonia is not completely decomposed, it will affect the catalysts that follow:) :)

When we talk about burning ammonia, it’s a rather general term. In fact, such high temperatures aren’t necessary for burning ammonia; however, certain substances that are produced as side reactions during the decomposition of ammonia can damage the catalysts, and high temperatures are required to burn these substances away. I’m not sure if that’s correct?

The key is to ensure complete ammonia combustion; furthermore, to guarantee thorough burning, the furnace temperature must reach a certain level of 930 degrees

Practice and theory have shown that ammonia burning indeed requires a high temperature. Generally, it is necessary to keep the residual ammonia content in the process gas after ammonia combustion below 20 ppm in order to ensure complete combustion of ammonia. Although the reaction between NH3 and SO2 begins at 700°C, to achieve complete ammonia combustion, the furnace temperature must be maintained at at least 1300°C. Otherwise, incomplete burning of ammonia will produce highly corrosive substances such as NO or NO2. This post was last edited by Clauspolunit on 2009-3-9 19:58]

To ensure that the NH3 content in the process gas after combustion is less than 50 ppm, several measures must be taken: the flame temperature must be above 1250°C； A certain excess amount of oxygen ； Dwell time of over 1.5 seconds ； Configure burners with mixed effects and excellent combustion performance.

In our sulfur processing process, it is said that at least 1250 degrees are required for complete decomposition of ammonia; in other words, only by reaching such high temperatures can it be completely decomposed, so that it no longer has any impact on subsequent reactions； 1. When the temperature in the sulfur production furnace is low, ammonia cannot be decomposed or is only partially decomposed, resulting in the formation of substances such as NO or NO2. NO then acts as a catalyst in subsequent reactions, converting SO2 into SO3. This substance reacts with Al2O3 to form AL2(SO4)3 and AL2(SO3)3, thereby causing the catalyst to become sulfated and losing its activity. 2. Incomplete decomposition of ammonia-based substances can cause blockages in the subsequent pipelines. With methods such as first cooling, second cooling, and third cooling, we can reduce the outlet temperature as much as possible by recovering sulfur; however, due to incomplete ammonia combustion, it is not possible to lower the temperature too much, otherwise the outlet will get blocked ； Secondly, there are the pipelines in the exhaust section; (especially in those units where the exhaust system has not yet been put into operation), ammonium salts form in areas with lower temperatures. Examples include ammonium sulfate, ammonium sulfite, ammonium sulfide, and ammonium bisulfate, which can clog the pipelines and lead to shutdowns. 3. The deactivation of the catalyst increases the load on the hydrogenation reactor; if hydrogenation does not take place in a timely manner, sulfur dioxide will enter the quench tower, causing the pH value to drop, which has an even greater impact. If ammonia is added, this increases the ammonia content in the wastewater, creating a vicious cycle with disastrous consequences, forcing shutdowns.