Simulating the process of desulfurization of gas condensate and checking the effective parameters in the efficiency of the unit

Dissertation for M.Sc.

Treatment: Environment

Abstract

Gas liquids from the refining of sour gases are also sour and contain a large percentage of hydrogen sulfide and mercaptans. Therefore, after distilling and preparing the products, it needs refining processes to remove or reduce the amount of sulfur and mercaptans present. Hydrogen sulfide and light mercaptans such as methyl mercaptan and ethyl mercaptan are very toxic and volatile compounds. By using the DMC process, the amount of hydrogen sulfide and methyl and ethyl mercaptans can be increased to a reasonable amount. The DMC process includes two processes, DMC-1 and DMC-2, in which the DMC-1 process includes two stages of extraction and oxidation. In the step of extracting mercaptans and hydrogen sulphide, they have reacted with interest, and the output from this step has entered the DMC-2 process. In this research, desulfurization of gas condensate is designed by HYSYS software. The purpose of the catalytic reactor is to convert RSNa into diM-disulphide, diE-disulphide, P-disulphide and B-disulphide. is The purpose of two-phase separation is to reduce diM-disulphide, diE-disulphide, B-disulphide, P-disulphide, NaS2O3* and Na2SO4* up to 99% in the vapor phase. With the increase in the air flow rate of the inlet, the amount of diM-disulphide, diE-disulphide and other disulphides from the outlet of the catalytic reactor has increased, and therefore the amount of disulphides from the two-phase and three-phase separator has increased. By increasing the flow rate of the input profit in DMC-1, it has increased the amount of RSNa* input to the catalytic reactor, and in the same way, it has increased the amount of disulfides coming out of the two-phase separator. With the increase in temperature, due to the principle of thermodynamics, the amount of disulfides coming out of the separating vapor phase has increased, so with the increase of the air flow and the inlet temperature and the temperature of the inlet air, the amount of disulfides coming out of the two-phase flash has increased, which makes the process go away from the goal. By increasing the air inlet pressure, the output flow rate from the two-phase separator has decreased and will bring the process closer to the target. Pressure changes have a greater impact on the amount of disulfides and process performance than other parameters, diM-disulphide will change more than other parameters due to parameter changes.

Introduction

Definition of Sulfur

Sulfur is one of the elements of the periodic table, it is part of nonmetals, it is in the third row and the sixth group, and it has an atomic number of 16 and a mass number of 32. Sulfur is one of the non-hydrocarbon derivatives of crude oil. Non-hydrocarbon derivatives of crude oil usually include sulfur-containing compounds, oxygen, and nitrogen. The percentage of these compounds in oil is not high. Oxygen compounds containing dust and dust contain approximately 2% of crude oil, although this percentage can be changed. These compounds are mostly found in heavy cuts. The amount of sulfur in household gas (6-4 ppm) and in [1] LPG is around (30 ppm).

All known oils practically contain sulfur. Oils obtained from South America and the Middle East and the Near East have more sulfur on average. The amount of sulfur in Iran is about 1.22% in Haft Gol crude oil and 2.46% in Khark crude oil. Oils from Eastern Europe, Far East, Indo-Pakistan, and Burma have less sulfur on average.]1 [

The two properties that have the most effect on the valuation of crude oil are [2] API sulfur content and crude oil. The amount of sulfur is expressed in terms of weight percentage of sulfur and varies between 0.1 and 5% (in crude oil). Oils that have more than 0.5% sulfur usually require extensive processing and desulfurization. Sulfur compounds in crude oil include: mercaptans, types of sulfides, polysulfides, thiophene compounds, which are concentrated in the heavy parts of crude oil. Hydrogen sulfide is also found in the light parts of crude oil. In some oils, elemental sulfur is also present.Uses of sulfur

Sulfur is generally a harmful substance that we try to eliminate, but sometimes it is used as a useful substance. One of the uses of sulfur is in the production of fertilizer. Urea fertilizer with sulfur coating is a type of slow release fertilizer (the meaning of slow release is that this fertilizer decomposes slowly in the soil) which has high efficiency and many benefits for soil and plants. This fertilizer is widely used in agricultural industries. Recently, in our country, due to the low efficiency of urea chemical fertilizers, its waste, severe contamination of soils and underground water sources with nitrates and nitrites, reduction of absorption of elements into the soils and so on. The use of this type of fertilizer is recommended for all agricultural lands that are completely submerged in water due to high pH. Because regardless of the above benefits, sulfur is used as a vital substance in the structure of proteins as a reducer and as a result, to create the conditions for the absorption of micronutrients, especially zinc. It should be noted that the people of our country have a record in iron and zinc deficiency in the whole world. [1] [

The harms of sulfur and the reasons for their removal

Organic sulfur compounds make up most of the content of sulfur compounds in crude oil. The amount of sulfur-containing organic compounds in Iran's crude oil is estimated between 0.25 and 3.23% by weight, so Iran is one of the countries that has the highest amount of sulfur-containing organic compounds in its oil reserves. Combustion of combustible materials derived from crude oil such as diesel and gasoline causes the production and release of sulfur oxides that cause environmental pollution and cause acid rain and deactivation of chemical catalysts. Also, acid rains cause the dissolution of building materials, the poisoning of lakes and the destruction of forests. A high percentage of dust in most petroleum products is harmful, and removing or converting them to harmless substances is one of the important tasks in refineries. The presence of sulfur compounds in gasoline is harmful because sulfur causes corrosion in different parts of the engine, especially in the solution in water, which is obtained as a result of combustion, and SO2 winter

causes severe corrosion of the crankshaft due to accumulation. In addition, mercaptans dissolved in petroleum products cause copper and brass corrosion directly in the vicinity of air. Mercaptans also have an adverse effect on lead sensitivity and color stability of products. Free sulfur is corrosive if present. The sulfur present in gasoline and other fuels causes air pollution and the release of SO2 gas due to combustion, therefore, the amount of sulfur must be reduced to its lowest level. high value of hydrogen sulfide and mercaptan. Therefore, after distillation and obtaining products, refining processes for removing reduced sulfur and mercaptan are necessary. Hydrogen sulfide and light mercaptans such as ethyl mercaptan and methyl mercaptan are highly toxic and unstable compounds. By using the DMC process, the amount of hydrogen sulfide, methyl mercaptan and ethyl mercaptan can be controlled to a reasonable amount. The DMC process is divided into two other processes called DMC-1 and DMC-2. The DMC-1 process, comprises of two stages: extraction and oxidation. In the extraction stage mercaptan and hydrogen sulfide react with sodium hydroxide and the result is sent to DMC-2 phase. In this study, desulfurization of gas liquids is designed using HYSYS. The purpose of the catalytic reactor is to convert RSNa into diM-disulphide, diE-disulphide, P-disulphide and B-disulphide etc. The purpose of the two-phase separator is to reduce diM-disulphide, diE-disulphide, B-disulphide, P-disulphide, NaS2O3 * and Na2SO4 * below % 99 in the vapor phase. By increasing the amount of intake air flow, the amount of diM-disulphide, diE-disulphide and other disulphides in the catalytic reactor increases. As a matter of fact, the amount of disulphides coming out of the two-phase and three-phase separating increases. The process is the goal. Increase in the input amount of sodium hydroxide in DMC-1 phase, increases RSNa amount in catalytic reactor.