Functional characteristics of desulfurizers

More than 100 sulfides have been identified in crude oil, which can be divided into three categories: the first category is acidic sulfur compounds, mainly including hydrogen sulfide and mercaptans; the second category is neutral sulfur compounds, mainly sulfides and disulfides. Sulfide. The third category is sulfides with good thermal stability, mainly including thiophene and tetrahydrothiophene. Sulfides are usually unpleasant, highly toxic and corrosive, and adversely affect the gathering and transportation of crude oil and the quality of refined oil products. Sulfide dissolved in crude oil will seriously corrode pipelines and equipment, threatening personal safety. Sulfide will cause a series of problems such as equipment corrosion, catalyst deactivation, and unqualified sulfur content of refined oil. At this time, desulfurization agent is needed for desulfurization.

The development of desulfurization agents and various desulfurization technologies has become an important means to solve the above problems. At present, desulfurization methods can be divided into absorption method, adsorption method, oxidation method, biological method, pulse corona method, etc. According to the process, it can be divided into regenerative solvent absorption desulfurization, fixed bed adsorption desulfurization, membrane separation desulfurization, biological desulfurization, and physical field desulfurization. According to the state of the substance, it can be divided into wet method and dry method. The following mainly introduces the research status of chemical desulfurizers for wet desulfurization.

Sodium hydroxide, potassium hydroxide and ammonia are also commonly used hydrogen sulfide removers for crude oil. Add chelating agent and demulsifier to remove iron and H2S in crude oil. The chelating agent consists of 28%~32% aminotrimethylenephosphonic acid, 7%~9% vinyl alcohol, 15%~18% urea, 10%~13% ammonia water and 0.5%~1% corrosion inhibitor composition, in which ammonia water is the main component to remove H2S. Some enterprises use ammonium hydroxide and ammonium sulfate as desulfurizers, and use new desulfurization devices to desulfurize crude oil.

NaOH and KOH can effectively remove hydrogen sulfide from crude oil, but form an alkaline-stable emulsion, which increases the difficulty of downstream dehydration process. Ammonium salt produced by the reaction of ammonia water and hydrogen sulfide is easier to remove than sodium salt in the downflow process, but ammonia water is prone to flash evaporation at higher temperatures, which is corrosive to equipment and causes environmental pollution. For the above reasons, hydroxide desulfurizers are rarely used at present.

H2O2 is a commonly used strong oxidizing desulfurizer, which has certain dangers. H2O2 is easily decomposed by metal catalysis, producing oxygen, water and a lot of heat, causing combustion or explosion. Potassium manganate solution cannot be used in acidic conditions, and the manganese dioxide produced may also cause combustion. Therefore, special attention should be paid to the operating conditions during use, which limits its application range.

Using the method of electrolysis of sodium chloride solution, the static desulfurization efficiency reaches 96.5%, and the dynamic desulfurization efficiency reaches 72.4%. This method mainly utilizes the generated strong oxidizing sodium hypochlorite to remove hydrogen sulfide in crude oil, but it has not been widely used. The strong oxidative desulfurizer can not only remove hydrogen sulfide in crude oil, but also can be combined with ionic liquid to remove organic sulfur in oil products, thereby enhancing the removal effect of organic sulfur, but its dosage should be strictly controlled.