Background Dangers of hydrogen sulphide Hydrogen sulphide, commonly known as H2S is awidely spread hazardous gas. Usually found with high levels of concentration innatural gasses and crude oils. Human exposure to H2S will yield anodor of rotten egg. Humans can also start to smell this odor at lowconcentrations of H2S, around 0.47 ppb. Many successful lawsuitshave been filed against H2S producers within the oil and gas sector,claiming the highly toxic gas gives them nausea. When humans are exposed to H2S,and the concentration increases with time, the rotten egg odor is no longersensible leading to high risks on health.
As of today, the minimum concentrationof H2S leading to risks on human life is 100 ppm. It isimportant to note that in some gas compositions H2S is present withhigher levels over 100 ppm. High levels of H2S mixed with air producesan explosive mixture. Corrosion is another problem relating to hydrogen sulphide,causing environmental issues exceeding $1.3 billion in damages. A currentreport analysing the industry spend on HSE (health, safety and environment) concernswill increase 60% by 2030. The cost of HSE concerns from oil companies in 2011was $36 billion, and in 2030 it is estimated to reach $56 billion.
The results ofthese increased costs will decrease the number of health breaches within thenext years.Treatment of hydrogen sulphide There are several processes used to eliminate hydrogen sulphide.Conventional tower aeration is one method used, which lowers the PH levels ofwater containing H2S to a certain degree that ensures the gaseoushydrogen sulphide remains within the dissolved gas form.
Another method used issimply burying H2S beneath the ground to prevent it from contamination.However, the most common method used to extract H2S from gases is theClaus process. Claus process is used in most if not all oil refinery companies.Hydrogen sulphide is first extracted from crude oils using gasification. H2Sthen undergoes a series of chemical reactions with oxygen rich environments in thefurnace, reaching temperatures exceeding 1000 oC. In this phase, onethird of H2S is burned (R1), resulting with sulphur dioxide andwater.
The remaining unburned hydrogen sulphide then reacts with sulphurdioxide in the next phase of the Claus process (R2), the catalytic reactions. Inthis phase, the gas is treated at much lower temperatures compared to theburner phase. Sulphur is formed and condensed to its precipitation point.
Thecatalytic reactions are then repeated several times to increase the productionof elemental sulphur. This literature review will focus on the burner phase of theClaus process, specifically relating to the formation of hydrogen sulphide. Betterunderstanding of the chemical reactions leading to H2S formation duringgasification will lead to an improved input into the combustion system.Therefore, increasing the efficiency of the burner phase in the Claus process. Formation of Hydrogen Sulphide Reaction Mechanism As discussed above, hydrogen sulphide is a very hazardousgas to be found in the atmosphere. It is well known to be a very chemicaldominant element. The presence of H2S will immensely change the chemicalkinetics of any chemical reaction it occurs in. Subsequently, the existence ofa reaction mechanism successfully representing the chemical kinetics of H2Sexperimentally will yield better results regarding H2S combustion.
Thisemphasised previous chemists and researchers to study and develop a numeric recreationof H2S in combustion.