Chemical precipitation method for removing calcium from crude oil

Abstract

The invention relates to a chemical precipitation method for removing calcium, characterized by that: a decalcification agent comprises urea, urase and crude oil demulsifier; the molar weight of urea is 2-5 times the molar weight of Ca in crude oil; the molar ratio of urase to urea is 1*10<-10> to 20*10<-10>; and the weight of crude oil demulsifier accounts for 20-100 mu g / g of the weight of the crude oil. The method comprises the following steps: preparing a decalcification solution with urea, urase and crude oil demulsifier, heating the decalcification solution to 30-60 DEG C, mixing the heated decalcification solution with the crude oil for 5 s-120 s at the temperature of 130-150 DEG C with the weight ratio of the decalcification solution to the crude oil of 0.05-0.20, dehydrating the mixed oil water mixture with a high frequency pulse highfield oil closed dehydrating device for 1 hour in the electric field of 130 DEG C for oil / water separating to obtain the decalcified crude oil. The chemical decalcification agent used in the invention has stable chemical property under normal temperature, does not etching devices, and has high decalcification effect. The calcium carbonate obtained after the reaction has no deleterious effects on human body and environment.

Description

Technical field [0001] The invention relates to a method for removing metals in crude oil by chemical methods, and more specifically, a method for decalcifying crude oil by using chemical precipitation agents. Background technique [0002] Part of the metallic calcium in crude oil is in the form of water-soluble salts, slightly soluble salts such as calcium chloride, calcium sulfate and other inorganic calcium salts, and the other part is in the form of organic calcium salts such as calcium petroleum acid. For the soluble salt and hydrophilic inorganic calcium salt particles, the refinery usually uses simple water washing in the electric desalination process to remove, but for the calcium petroleum acid existing in the oil phase, this rule has almost no removal effect. The presence of calcium salt will have many negative effects on subsequent crude oil processing. [0003] The known chemical crude oil decalcification technology can be roughly attributed to chemical chelation, chem...

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Problems solved by technology

The disclosed crude oil decalcification technology such as CN8610728A, CN1036981A, CN87105863 belongs to the chemical chelation method, and it mainly adopts the aminocarboxylic acid, dibasic carboxylic acid, hydroxycarboxylic acid etc. that can generate water-soluble chelate with the Ca ion in the crude oil to decalcify the crude oil. Decalcification, this type of method is relatively expensive in medicament price and high in industrial production cost; the disclosed crude oil decalcification technology such as CN1112424C, CN1454967A belongs to the chemical acid treatment method, and this type of technology is the principle of using organic or inorganic medium strong acid to replace petroleum acid calcium To remove calcium in crude oil, although the one-time crude oil decalcification rate is as high as more than 90%, the disadvantage is that the industrial acid used is not friendly to the environment and has a corrosive effect on industrial equipment, so corrosion-resistant equipment needs to be selected; CN1055552A, CN1054261A, CN1078234C , ZL2005100707973 and other disclosed crude oil decalcification technologies belong to the chemical precipitation method, which uses water-soluble sulfate, phosphate, hydrogen phosphate di-salt and calcium petroleum acid in crude oil to generate slightly soluble or insoluble calcium sulfate, phosphoric acid Calcium and calcium hydrogen phosphate, under the action of solid wetting agent, are deposited in the water phase to achieve the purpose of decalcification. This method is more friendly to the environment and equipment. The material needs to be treated with special separation equipment

From the perspective of application, ammonium carbonate will have a great impact on the environment and human body during storage, transportation and use. Now, enterprises are increasingly aware of the protection of employees' personal health, which affects the application of this decalcifying agent.

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