Journal of Gas Technology
Volume:7 Issue: 2, Winter 2022

Flare gas recovery is one of the essential processes in reducing the greenhouse gas emissions caused in the oil and gas industry. On the other hand, due to the reduction of pressure and production rate of hydrocarbon reservoirs especially in Iran, it is necessary to provide solutions for reservoirs pressure maintenance. Therefore, in this paper the potential application of the separated carbon dioxide from the flare gas in Parsian refinery was investigated for injection into a gas condensate reservoir. For this purpose, the flare gas recovery process was simulated using Aspen HYSYS software and operational enhancements were applied. Next, the injection of the separated carbon dioxide into a gas condensate reservoir was simulated in Petrel software, and the best scenario was determined. The obtained results indicated that maximum CO2 recovery is achieved using Diisopropanolamine as solvent with the flow rate 1930 USGPM. The reservoir simulation results revealed that CO2 injection prevents severe pressure drop and causes the reservoir pressure to decline with a lower slope. Thus, the reservoir production rate increases and becomes more stable. The most stable production rate was attained for injection rate of 305 million cubic meters per day.

The sweetening of sour gas by amine solvent has attracted a lot of attention due to the high ability of amines to remove acidic compounds from natural gas. In this process, an adsorption column and a distillation column are used to recover the amine. The operating costs of the conventional sour gas sweetening process are very high due to the high energy consumption in the solvent recovery column. Therefore, process energy optimization is very essential. In this research, first, the conventional gas sweetening process was subjected to heat integration (HI) so instead of using utility in supplying process energy, the energy of process flows has been used. Then, the amine recovery column is thermally integrated into this process by Vapor Recompression (VRC) and Bottom Flashing (BF) methods. The results showed that the HI, VRC, and BF processes reduced energy consumption compared to the conventional process about 25%, 88%, and 90%, respectively. Although the compressor consumption of the VRC and BF processes is almost the same, the reduction in hot and cold utility consumption in BF is 33% higher than in VRC. So, the BF process performs better than the VRC process. Moreover, BF process could reduce total annual cost (TAC) of the base process in the maximum value of 96%. That is why BF process is selected as the best choice of heat integration in this case study.

Today, producing clean fuel oil is one of the major challenges in the world. One of the factors that causes environmental pollution is the sulfur compounds in crude oil. In today's world, there are strict rules for reducing the amount of sulfur in fuel. There are several ways to remove sulfur compounds from fuels, such as hydrodesulfurization (HDS), extractive distillation, biodesulfurization, adsorption desulfurization, and oxidative desulfurization (ODS). Some refractory sulfur compounds that are not removed from the fuel oil by the HDS can be easily removed by oxidation method. Nowadays, the ODS method is known as a complement to the HDS method. In the oxidation method, sulfur compounds are converted to the corresponding sulfonates by catalysts and oxidants and then separated from the feed by polar solutions or adsorbents. Various researches have been done on the Catalysts and oxidants of the ODS method. In this study, a comprehensive review has been carried out on the application of nanotechnology in the oxidative desulfurization method. Based on previous researches and available articles, nanocatalysts used in the oxidation process can be classified into five groups; polyoxometalates, transition metal oxide, carbon materials, ionic liquids and metal-organic frameworks (MOF). Also, different nanocatalysts and oxidants and optimal conditions to achieve the highest conversion percentage for the removal of sulfur compounds were investigated.

Globally, Iran ranks 6th in natural gas production. Producing over 1 billion cubic feet of dry natural gas, the Gachsaran gas refinery is a major revenue source for the country. Tens of thousands of barrels are sent to the Bandar-e-Emam petrochemical plant every day, and the Gachsaran oil and gas refinery always aims to partially supply the feed for this petrochemical complex by sweetening sour natural gas feed containing some H2S and CO2. Due to the high energy consumption of the sweetening unit, energy optimization of this process is significant. Vapor Recompression Column was used for optimizing sweetening process energy in the Gachsaran gas unit, and the distillation column's top vapor was compressed to transfer its thermal energy to the bottom. The results show that Vapor Recompression Column consumed about 75% less energy than the conventional process mostly due to warm and cold utility savings. The output pressure of the compressor added in this process was calculated accurately. If the compressor output pressure increases excessively, this method becomes inefficient and uneconomical.

In the 21st century, the petrochemical industry has experienced a significant increase in oil and gas consumption due to the growing global population and energy demand. Among nonrenewable resources, natural gas stands out as the cleanest option, making it an essential resource for the energy industry in comparison to other hydrocarbons. Unconventional gas, including shale gas, tight gas, coalbed methane, and gas hydrate, has emerged as a substantial hydrocarbon resource. This study aims to explore the environmental impacts, geological features, obstacles, and technical challenges associated with the exploitation of unconventional gas reservoirs, encompassing aspects such as energy demand, consumption and production, water pollution, greenhouse gas emissions, and reservoir geology properties. The paper also reviews the various approaches to developing unconventional gas in different countries, with a particular focus on the United States. The findings indicate that the feasible development of unconventional gas is indeed possible in different countries. However, the future outlook for this resource will heavily rely on several factors, including addressing environmental concerns, investment in renewable energy, and the state of global gas markets.

The sweetening unit of the Ilam Gas Refinery plays a major role in providing olefin feed, and at the present time, the provinces of Ilam, Kermanshah, Hamedan, Kurdistan, and Lorestan in Iran are the consumers of the gas produced by this refinery. The gas sweetening unit of the Ilam Gas Refinery has an absorption and distillation column. H2S and CO2 are removed by diethanolamine in the absorption column, and the entrainer is recovered in the distillation column. The concern is the high energy consumption of this process, particularly the distillation column. In this study, a novel method for heat integration of the distillation column of the gas sweetening unit of the Ilam Gas Refinery was used, so that the feed entering the distillation column was splitted into two sections prior to feeding. Afterwards, the bottom section was preheated by the bottom product of column. Preheating the bottom section of feed decreased the reboiler and condenser duties. The results demonstrate that the proposed method decreases the energy consumption by 17%.