![]() ![]() ![]()
In this paper, the enthalpy-concentration method was applied in order to model a steady-state continuous methanol–water mixture distillation column. This work. CC-STEADY STATE. Chemical process simulation software that includes libraries of chemical components, thermodynamic methods, and unit operations to allow steady-state. Simulation of hydrodesulfurization unit for natural gas condensate with high sulfur content. Looking at the world's growing demand for new energy resources, experts in the field of oil and energy can obviously realize that oil industry has to find new fuel supplies and upgrade their qualities. The natural gas condensates can catch their attention as they contain complex mixtures of hydrocarbon components. Natural gas condensate is known as a low- boiling mixture of hydrocarbon liquids that are present as gaseous components in the raw natural gas produced from many natural gas fields [1]. Therefore, in addition to crude oil, the natural gas condensate can be an appropriate resource for oil industry to augment the fuel production. According to the report of International Energy Agency (IEA), the South Pars/North Dome field, which is located in the Persian Gulf, is the world’s largest gas field and shared between Iran and Qatar. This field holds an estimated 1. However, the gas condensate of this field is substantially sour as it is estimated that the sulfur content of gas condensate of South Pars field is more than 2. The sulfur content of fuels is currently considered as a major factor contributing to pollution of the atmosphere. Accordingly, the U. S. Environmental Protection Agency limited the sulfur content of most diesel fuels to 1. The similar environmental regulations in Europe forced petroleum industries to reduce the sulfur content for on- road diesel fuels from the level of 3. Furthermore, based on the Euro V criterion, the bound for fuels, in terms of total sulfur content has to be less than 1. The sulfuric compounds in fossil fuels are divided into non- aromatic and aromatic compounds. The first group includes sulfides, disulfides, and mercaptans (thiols) and the second one includes thiophenes, benzothiophenes, dibenzothiophenes, and benzonaphthothiophenes. The former has much more reactivity than the other sulfuric compounds while the latter, particularly benzothiophenic and dibenzothiphenic derivatives, are difficult to desulfurize. Hydrodesulfurization (HDS) is known as one of the most efficient methods to reduce the sulfur content of hydrocarbons regarding universal criteria. This process can be extremely effective in removing both types of sulfuric compounds. In this plant, the reaction takes place under high temperature and high hydrogen pressure in the presence of a catalyst. HDS process can accomplish desulphurization and in the meanwhile it can remove nitrogen and metal compounds, and also carry out deoxidation. Based on the advantages of hydrodesulfurization process—removing less than 1. There are some studies investigating the simulation and modeling of HDS plants. The research conducted by S. Bilal et al. [8] focused on the simulation of an HDS unit using Aspen HYSYS with the aim of removing impurities such as sulfur and nitrogen from raw kerosene. F. Jiménez et al. Hydrodesulfurization (HDS), Hydrodenitrogenation (HDN), and Hydrodearomatization (HDA) of a vacuum gasoil (VGO) in which reactions took place in industrial reactors. Another study explored the use of different artificial neural network (ANN) architectures in creating various models of the HDS process for the prediction of sulfur removal from naphtha [1. Ultra- Deep Hydrodesulfurization (UDHDS) process is considered as one of the subbranches of the conventional HDS process which is conducted in the severe process conditions and using different catalyst to obtain the lower amount of sulfur content. In addition to the HDS unit, a distillation system is required to obtain clean cuts. However, the order of these two sections is a problem. Based on a technical recommendation study report given by HQCEC, the hydrogenation plus fractionation process to treat naphtha can produce clean product with high quality and low impurity content compared with the fractionation plus hydrogenation units. Moreover, the energy consumption of these two plants was approximately equal. In terms of investment, the system capacity of hydrogenation plus fractionation process is slightly higher than that of the fractionation plus hydrogenation processes [1. However, in these studies, costs and problems caused by sour petroleum cuts have been ignored. Gas condensate of South Pars field is currently sent to refineries to produce fuel cuts or sold in markets. In both cases, gas condensate with high sulfur content or sour petroleum cuts can seriously damage pipelines and process equipment due to corrosion and push up the cost of process. In the present study, it has been assumed that the primary design of sulfur removal unit for gas condensate should be based on the UDHDS plant plus a fractional distillation unit. Regarding the world's increasing need for clean fuels as well as environmental issues resulting from high- sulfur fuel burning, it was assumed that a new UDHDS unit treating the natural gas condensate of South Pars field and producing the ultra- low sulfur fuel cuts from them would attract investments and get back more interests in the universal markets. Moreover, this process can protect downstream equipment from corrosion and cut down costs of maintenance. Furthermore, there is an environmental issue which is related to the production of disulfide oil. The substance, commonly known as disulfide oil (DSO), can comprise 1. C4. Evidence demonstrates that the lowest series member, dimethyl disulfide (DMDS), can display the highest toxicity. DSO possesses high aquatic toxicity, moderate environmental persistence, high repeated dose toxicity, carcinogenicity, and reproductive/developmental effects [1. DSOs (mainly dimethyl and diethyl disulfides) are formed in considerable amounts in the process of hydrocarbon demercaptanization in refineries. Presently, there is no practical application for DSO. Furthermore, destruction of DSO by combustion would lead to the formation of sulfur dioxide and carbonyl compounds which can pollute the atmosphere. Fortunately, DSOs are highly active in the catalytic reaction with hydrogen and they can be easily removed and converted to alkanes and hydrogen sulfide in the hydrodesulfurization process. Therefore, the aim of this study is the simulation of a new UDHDS unit plus a distillation section in South Pars refinery which would treat the natural gas condensate with high sulfur content and produce clean and sellable fuel cuts. Moreover, regarding aforementioned problems caused by DSOs in this refinery, in this simulation a stream of DSOs was added to gas condensate which was sent to UDHDS unit as a feed. The simulated UDHDS unit plus distillation section would treat gas condensate and totally remove DSOs from this refinery. The results of the present work can be used to build a new UDHDS unit to treat the gas condensate of South Pars field and produce clean fuel cuts. The main difference between this UDHDS process and conventional UDHDS processes is related to the feed of this simulated unit which is a combination of gas condensate and DSO while the feed of the conventional UDHDS units is usually petroleum cuts like naphtha, gasoil, or kerosene. In this simulation, it was assumed that the total sulfur content of gas condensate after treatment should reach less than 1. At the end, a distillation column was joined to the simulation in order to obtain the clean cuts of butane, light and heavy naphtha, kerosene, and Gasoil from treated gas condensate.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. Archives
November 2017
Categories |