Kinetic Simulations of H₂ Production from H₂S Pyrolysis in Sulfur Recovery Units Using a Detailed Reaction Mechanism

Abstract

Acid gas (H 2 S and CO 2 ) is produced in large volumes worldwide from the desulfurization of hydrocarbon fuels and is utilized in sulfur recovery units (SRUs) to produce sulfur. However, the hydrogen content of acid gas is wasted as lowgrade steam, which highlights the need for the efficient utilization of this resource. The production of H 2 from acid gas is desired, as it is an inexpensive feedstock. In this work, a kinetic study is conducted on H 2 production from acid gas in an industrial SRU to utilize its built-in inertia, while saving on the capital cost and enhancing the processing capacity of the SRU. The thermal energy generated during the combustion of acid gas in the reaction furnace (RF) is used for acid gas pyrolysis in the waste heat boiler (WHB) of the SRU. While this technique has been investigated previously, its realization at the industrial scale is hindered by low H 2 yield. This paper presents suitable means of enhancing H 2 production via operational modifications in RF and WHB. A detailed reaction mechanism, developed for acid gas combustion and pyrolysis and validated using experimental data from industrial furnaces and reactors, is used for the kinetic simulations of the SRU thermal unit. The results show that RF operational changes such as the extent of H 2 S oxidation and feed preheating can increase H 2 yield from 3% to 38% in the WHB without changing the composition of the acid gas stream. This significant improvement in H 2 yield can help in realizing its production from acid gas in SRUs.

Kinetic Modeling Study of the Industrial Sulfur Recovery Process for Operating Condition Optimization

“…A mechanism for the formation of CS 2 is given by Petherbridge et al [28]. ey presented a sequence of reactions leading to the formation of CS 2 as follows: (10) eir model agreed fairly well with the experimental data, and even experimental errors in the species concentrations have been taken into consideration [21].…”

“…And, equation (3) leads to the production of H 2 , and hydrogen is a species which deserved consideration in the Claus process. As seen in the literature, Cong et al [8], Ravikumar et al [10], Savelieva et al [22], and Li et al [23] have studied the way to increase hydrogen production via the thermolysis and oxidation of hydrogen sulfide (H 2 S).…”

“…e authors in [8,9] built a detailed reaction mechanism of the acid gas, and they used this mechanism to do a CFD simulation of the reactor furnace of the sulfur recovery units which focused on the flow fields of the process. en, the authors in [3,10] also did a kinetic simulation of acid gas destruction with a detailed mechanism for simultaneous syngas and sulfur recovery, and their work investigated the optimal operating conditions for H 2 production other than sulfur recovery. Manenti et al [11][12][13][14][15] did much work on the modeling simulation of the sulfur recovery process, and their work covered not only the revision of the combustion mechanism but also the optimization of the operating conditions for sulfur recovery.…”

Fuel Production from Seawater and Fuel Cells Using Seawater

“…[97] Figure 11 shows the H 2 Sc onversion and yields of H 2 and S 2 with af eed stream composed of 5mol %H 2 Sa nd 95 mol %A ru nder 1bar pressurea td ifferentt emperatures, which are fitted by the computed time profiles based on the proposed mechanisms. [97,98] Because highert emperatures (above1 200 8C) are required to obtain an H 2 yield above 30 %, [99] La 2 SrO x was used as an effective catalyst to decrease the temperature to 950 8Ct oo btain the highest conversion of 35.7 %f or the decomposition of H 2 S. [100] The resultsf rom the laboratory-scale extraction pilot plant unit for the separation of H 2 Sf rom Black Sea deep water enabled the buildingo fa ni ndustrial extraction pilot plant to concentrate H 2 Sf rom 10 ppm to above 10 000 ppm. [101] The processing of 10 9 m 3 of water containing 10 ppm H 2 Sw ould produce only 0.833 tons of H 2 .…”

Modeling Thermal Part of Sulfur Recovery Unit and Simulation Based Analysis of Effects of Air Temperature on Entire Plant

“…On the other hand; beside their low cost, "opportunity crudes" with various compositions and increase in the sulfur content of the feed stocks [2] became pain in the neck when it comes to processing the crude oil. Moreover, because of the developing technology and constant demand [3], worldwide sulfur import and export values were halved in 4 years [4,5]. Above mentioned progresses faced companies to treat acid gas more effectively to reduce the emissions and operational costs.…”