Method and device for removing metal ions from hydrocarbon oil

Abstract

A method and device for removing metal ions from hydrocarbon oil. The method comprises the following steps: S1, subjecting hydrocarbon oil and an aqueous solution of a decalcification agent to an electro-desalting treatment, so as to obtain demetallized hydrocarbon oil and a reacted aqueous solution of the decalcification agent; S2, subjecting the reacted aqueous solution of the decalcification agent to membrane separation, so as to obtain a concentrated solution of a reaction product of calcium ions and the decalcification agent, a first sodium-ion-containing concentrated solution and fresh water; S3, subjecting the concentrated solution of the reaction product of the calcium ions and the decalcification agent to a decalcification treatment, so as to obtain a decalcified concentrated solution of the decalcification agent; and S4, evaporating and condensing the first sodium-ion-containing concentrated solution, so as to obtain a second sodium-ion-containing concentrated solution and condensate water, mixing the decalcified concentrated solution of the decalcification agent, the fresh water and the condensate water, and returning the resulting mixture to S1. The method achieves the recycling of a hydrocarbon oil decalcification agent, the cyclic decalcification of hydrocarbon oil and the resource utilization of hydrocarbon oil decalcification wastewater.

Description

Method and device for removing metal ions from hydrocarbon oil

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Chinese patent application No. 202311123648.3 filed on August 30, 2023, the contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to the field of petroleum processing wastewater treatment, and in particular to a method and a device for removing metal ions from hydrocarbon oil. Background Art

[0004] As crude oil resources become increasingly heavier, the metal ion content in crude oil is trending higher. The presence of high concentrations of metal ions such as calcium and magnesium significantly limits further improvements in crude oil processing depth. Currently, a common approach is to add chemical agents such as decalcifiers to the crude oil electro-desalting and dehydration process to increase the removal rate of metallic calcium. However, the introduction of these chemicals can alter the quality of the electro-desalting wastewater produced during the demetallization process. Therefore, achieving efficient treatment of electro-desalting wastewater has been a technical bottleneck hindering the industrialization of the decalcification process.

[0005] CN86107286A, CN1036981A, CN1267707A, CN87105863A, CN1657596A, CN1431277A, CN1554967A, CN1982413A, CN101085932A, and CN101067012A disclose hydrocarbon oil demetallization processes using a disposable decalcifying agent. These processes have advantages such as significant demetallization effect and simple operation. However, the industrial wastewater generated during the demetallization process has the disadvantage of causing serious environmental pollution. If incorporated into the refinery wastewater treatment system, it may even lead to unreasonable external drainage.

[0006] CN1202208C discloses a hydrocarbon oil demetallization cycle method that utilizes a cycle to remove metallic calcium from hydrocarbon oil, allowing the hydrocarbon oil decalcifying agent to be recycled, thereby reducing the cost of the agent. However, this process also involves the circulation of the desalinated water, which can affect the normal operation of the electrical desalination device. Furthermore, scaling of pipelines or reactors is a common problem during industrial implementation. Furthermore, this technology requires strict control over the amount of precipitant used to avoid corrosion of the device, poor water quality of the discharged water, and increased operating pressure of subsequent sewage treatment equipment.

[0007] CN105733664A discloses a series of treatments for organic acid calcium wastewater. When the calcium ion concentration in the crude oil electric desalination wastewater is greater than 20,000 μg / g, all or part of it is discharged into a water treatment process system, and then treated through processes such as acidification, solid-liquid separation, extraction, distillation, and stripping. The treated wastewater is then discharged to a sewage treatment plant. However, scaling of pipelines or reactors still exists in the distillation unit, and the required equipment has a large processing capacity, and the dosage and energy consumption of the decalcifying agent are high, resulting in a great waste of resources and great engineering difficulty.

[0008] CN102399581A discloses using ion exchange resin instead of decalcifying agent, and regenerating the demetallized resin after acid treatment. However, there are problems such as short service life of the resin and difficulty in engineering.

[0009] Therefore, there is an urgent need for a hydrocarbon oil demetallization process that can treat metals in crude oil, recycle wastewater, waste residue and decalcifying agents, and achieve miniaturization and cleanliness of the equipment.

[0010] Summary of the Invention

[0011] The present invention aims to overcome the high pollution emissions associated with prior art hydrocarbon oil decalcification processes by providing a method and apparatus for removing metal ions from hydrocarbon oil. This method not only achieves recycling of hydrocarbon oil demetallization, but also converts the metal ions removed from the hydrocarbon oil into resources and recycles the wastewater from hydrocarbon oil decalcification, thereby achieving low carbon emissions, environmental protection, and a circular economy.

[0012] In order to achieve the above object, the first aspect of the present invention provides a method for removing metal ions from hydrocarbon oil, wherein the method comprises the following steps:

[0013] S1, subjecting the hydrocarbon oil and the decalcifying agent aqueous solution to an electrical desalting treatment to obtain a demetallized hydrocarbon oil and a reacted decalcifying agent aqueous solution;

[0014] S2, membrane separation of the decalcifying agent aqueous solution after the reaction to obtain a concentrated solution of the reaction product of calcium ions and the decalcifying agent, a first sodium ion-containing concentrated solution and fresh water;

[0015] S3, decalcifying the concentrated solution of the reaction product of the calcium ions and the decalcifying agent to obtain a decalcified decalcifying agent concentrated solution;

[0016] S4, evaporating and condensing the first sodium ion-containing concentrated solution to obtain a second sodium ion-containing concentrated solution and condensed water; mixing the decalcified decalcifying agent concentrated solution, the fresh water and the condensed water and returning the mixture to S1.

[0017] A second aspect of the present invention provides a device for removing metal ions from hydrocarbon oil, wherein the device comprises:

[0018] an electric desalting unit for conducting an electric desalting treatment on hydrocarbon oil and a decalcifying agent aqueous solution to remove metal ions in the hydrocarbon oil;

[0019] a membrane separation unit, used for performing membrane separation on the water phase flowing out of the electrical desalination unit;

[0020] an evaporation and condensation unit, used for evaporating and concentrating the sodium ion concentrate flowing out of the membrane separation unit, and condensing the obtained gas phase product into condensed water;

[0021] The decalcification treatment unit is used to decalcify the concentrated liquid of the reaction product of calcium ions flowing out of the membrane separation unit and the decalcification agent, and mix the obtained liquid product, the fresh water flowing out of the membrane separation unit and the condensed water flowing out of the evaporation and condensation unit and return them to the electric desalination unit.

[0022] Through the above technical solution, the beneficial effects of the present invention include at least:

[0023] The present invention performs membrane separation on the decalcifying agent aqueous solution obtained after electro-desalting, concentrating the decalcifying agent aqueous solution to a certain concentration. This reduces the processing capacity of subsequent solidification (precipitation) and regeneration processing equipment, thereby achieving miniaturization of industrial equipment. The present invention utilizes a cyclic process for removing calcium ions from hydrocarbon oil, effectively overcoming the shortcomings of conventional hydrocarbon oil decalcification methods, in which the hydrocarbon oil decalcifying agent is used once and then discharged with the desalted water, resulting in high COD emissions and high decalcification costs. This allows the hydrocarbon oil decalcifying agent and electro-desalting wastewater to be recycled. Furthermore, the present invention converts the metal ions removed from the hydrocarbon oil into corresponding salts and can also recycle the removed metal calcium, barium, and sodium salts. The resulting metal salt product can be of a quality exceeding qualified grade, thereby effectively utilizing the removed metal salt residue resources. This allows for resource-based utilization of the hydrocarbon oil decalcifying agent and hydrocarbon oil decalcification wastewater, significantly reducing hydrocarbon oil demetallization costs to below 80%, and reducing COD emissions by 100%. Therefore, the present invention has the advantages of transforming waste into valuables, achieving zero wastewater and waste residue discharge, and being environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] FIG1 is a flow chart of a method for removing metal ions from hydrocarbon oil according to a specific embodiment of the present invention.

[0025] DESCRIPTION OF REFERENCE NUMERALS 1 hydrocarbon oil 2 mixer 3 electric desalting tank 4 demetallized hydrocarbon oil 5 aqueous solution of decalcifying agent after reaction 6 microfiltration purification system 7 filtrate after pretreatment 8 nanofiltration system 9 concentrated solution of reaction product of calcium ions and decalcifying agent 10 filtrate containing sodium ions 11 reverse osmosis system 12 fresh water without metal salts 13 first concentrated solution containing sodium ions 14 evaporation and condensation unit 15 second concentrated solution containing sodium ions 16 evaporated condensed water 17 brine storage tank 18 first precipitant storage tank 19 second precipitant storage tank 20 first solidification reaction tank 21 feed liquid containing calcium sulfate precipitate 22 first solid-liquid separator 23 first recovered concentrated water 24 calcium salt slag tank 25 first drying system 26 calcium sulfate product 27 second solidification reaction tank 28 feed liquid containing barium sulfate precipitate 29 second solid-liquid separator 30 barium salt slag tank 31 second drying system 32 barium sulfate product 33 second recovered concentrated water 34 hydrocarbon oil decalcifying agent aqueous solution tank 35 recovered aqueous solution containing hydrocarbon oil decalcifying agent 36 water DETAILED DESCRIPTION

[0026] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0027] A first aspect of the present invention provides a method for removing metal ions from hydrocarbon oil, wherein the method comprises the following steps:

[0028] S1, subjecting the hydrocarbon oil and the decalcifying agent aqueous solution to an electrical desalting treatment to obtain a demetallized hydrocarbon oil and a reacted decalcifying agent aqueous solution;

[0029] S2, membrane separation of the decalcifying agent aqueous solution after the reaction to obtain a concentrated solution of the reaction product of calcium ions and the decalcifying agent, a first sodium ion-containing concentrated solution and fresh water;

[0030] S3, decalcifying the concentrated solution of the reaction product of the calcium ions and the decalcifying agent to obtain a decalcified decalcifying agent concentrated solution;

[0031] S4, evaporating and condensing the first sodium ion-containing concentrated solution to obtain a second sodium ion-containing concentrated solution and condensed water; mixing the decalcified decalcifying agent concentrated solution, the fresh water and the condensed water and returning the mixture to S1.

[0032] The method provided by the present invention can be used to remove metal ions from various hydrocarbon oils. For example, the hydrocarbon oil can be a reduced-four fraction oil with metal ion contents of 40.4 μg / g calcium ion, 5.13 μg / g magnesium ion, and 2.8 μg / g sodium ion; it can be a crude oil with metal ion contents of 520 μg / g calcium ion, 5.64 μg / g magnesium ion, and 120.1 μg / g sodium ion; it can be a heavy oil with metal ion contents of 712 μg / g calcium ion, 2.53 μg / g magnesium ion, and 95.8 μg / g sodium ion; it can be an extra-heavy oil with metal ion contents of 1380 μg / g calcium ion, 14.32 μg / g magnesium ion, and 282 μg / g sodium ion; it can be a metal ion content of 27.3 μg / g calcium ion, 27.3 μg / g magnesium ion, and 27.3 μg / g sodium ion. / g, magnesium ion 0.32μg / g, sodium ion 0.8μg / g of dirty oil; it can be crude oil with metal ion content of 208μg / g calcium ion, 3.14μg / g magnesium ion, and 41.7μg / g sodium ion; it can be residual oil with metal ion content of 1469μg / g calcium ion, 4.3μg / g magnesium ion, and 123.5μg / g sodium ion; it can be extra heavy oil with metal ion content of 1980μg / g calcium ion, 23.7μg / g magnesium ion, and 98.1μg / g sodium ion; it can be extra heavy oil with metal ion content of 2250μg / g calcium ion, 20.3μg / g magnesium ion, and 94.1μg / g sodium ion.

[0033] After the hydrocarbon oil decalcifying agent aqueous solution is fully mixed with hydrocarbon oil, an electric desalting process is performed, and the metal ions in the hydrocarbon oil enter the decalcifying agent aqueous solution to obtain demetalized hydrocarbon oil (oil phase) and a post-reaction decalcifying agent aqueous solution, wherein the post-reaction decalcifying agent aqueous solution is an aqueous solution (aqueous phase) containing a compound formed by the reaction of the decalcifying agent and calcium ions and sodium chloride. The post-reaction decalcifying agent aqueous solution is subjected to membrane separation to obtain a concentrated solution of the reaction product of the calcium ions and the decalcifying agent (the compound formed by the reaction of the decalcifying agent and the calcium ions is retained by the membrane separation to form a concentrated solution of the reaction product of the calcium ions and the decalcifying agent), a first concentrated solution containing sodium ions, and fresh water free of metal salts. The first concentrated solution containing sodium ions is further evaporated, concentrated, and condensed to obtain a second concentrated solution containing sodium ions and evaporated condensate. The concentrated solution of the reaction product of the calcium ions and the decalcifying agent is decalcified, mixed with the fresh water free of metal salts and the evaporated condensate, and then fully mixed with the hydrocarbon oil in a desired ratio for recycling, thereby achieving the recycling of the hydrocarbon oil decalcifying agent, the recycling decalcification of the hydrocarbon oil, and the resource utilization of the hydrocarbon oil decalcification wastewater.

[0034] According to the present invention, preferably, in S3, the decalcification treatment method includes: mixing the concentrated solution of the reaction product of the calcium ions and the decalcifying agent with a first precipitant to perform a first precipitation reaction, and then performing a first solid-liquid separation; mixing the obtained liquid phase product with a second precipitant to perform a second precipitation reaction, and performing a second solid-liquid separation to obtain the decalcified decalcifying agent concentrated solution.

[0035] According to the present invention, preferably, the conditions for the first solid-liquid separation include: a temperature of 20-50° C. and a pressure of -0.1 MPa to 1 MPa.

[0036] According to the present invention, preferably, the first precipitant is sulfuric acid or phosphoric acid.

[0037] In the present invention, the amount of the first precipitant is the theoretical amount of the first precipitant when it completely reacts with the calcium ions in the concentrated solution of the reaction product of the calcium ions and the decalcifying agent.

[0038] According to the present invention, preferably, the temperature of the first precipitation reaction is 20-50° C., and the time is 5-30 min.

[0039] According to the present invention, preferably, the conditions for the second solid-liquid separation include: a temperature of 20-50° C. and a pressure of -0.1 MPa to 1 MPa.

[0040] According to the present invention, preferably, the second precipitant is barium chloride, barium hydroxide or barium acetate.

[0041] In the present invention, the amount of the second precipitant is the theoretical amount of the second precipitant when it completely reacts with the sulfate or phosphate contained in the liquid product obtained by the first precipitation reaction.

[0042] When the first precipitant is sulfuric acid or phosphoric acid, and the second precipitant is barium chloride, barium hydroxide, or barium acetate, the concentrated solution of the reaction product of the calcium ions and the decalcifying agent is mixed with sulfuric acid (or phosphoric acid) to perform a first precipitation reaction. The sulfuric acid (or phosphoric acid) reacts with calcium to form a supersaturated solution of calcium sulfate (or calcium phosphate). The calcium sulfate (or calcium phosphate) precipitates in the form of a solid, and undergoes a first solid-liquid separation to obtain solid calcium sulfate particles or solid calcium phosphate particles. A portion of the dissolved calcium sulfate (or calcium phosphate) dissolves in the form of calcium ions and sulfate ions (or phosphate ions) in the liquid phase product obtained by the first solid-liquid separation. The liquid phase product obtained by the first solid-liquid separation is mixed with barium chloride, barium hydroxide, or barium acetate to perform a second precipitation reaction. The barium ions react with the sulfate ions (or phosphate ions) contained in the liquid phase product. After a second solid-liquid separation, solid barium sulfate particles or solid barium phosphate particles are obtained, while the calcium ions continue to dissolve in the form of ions in the liquid phase product obtained by the second solid-liquid separation.

[0043] According to the present invention, preferably, the temperature of the second precipitation reaction is 20-50° C., and the time is 5-30 min.

[0044] In the present invention, solid-liquid separation can be performed after static sedimentation, solid-liquid separation can be performed after centrifugation, or solid-liquid separation can be performed using a filter.

[0045] According to the present invention, preferably, in S1, based on the weight of the hydrocarbon oil, the contents of the decalcifying agent and water in the decalcifying agent aqueous solution are 0.01-5 wt% and 1-25 wt%, respectively.

[0046] When the concentration of the hydrocarbon oil decalcifying agent in the aqueous solution formed by mixing the decalcified decalcifying agent concentrate, the fresh water and the condensed water is higher than the required ratio of the decalcifying agent to the hydrocarbon oil, a certain amount of water is added until the concentration of the hydrocarbon oil decalcifying agent in the aqueous solution meets the required ratio of the hydrocarbon oil decalcifying agent to the hydrocarbon oil.

[0047] According to the present invention, preferably, the decalcifying agent is selected from at least one of formic acid, acetic acid, propionic acid and butyric acid.

[0048] According to the present invention, preferably, the process of the electrical desalination treatment comprises: mixing the hydrocarbon oil and the decalcifying agent aqueous solution at a temperature of 50-150° C. and a pressure of 0.02-1 MPa, controlling the diameter of the oil and water particles to be within the range of 0.1-50 μm; then retaining the mixture at an electric field strength of 50-500 V / cm for 1-60 minutes, and then retaining the mixture at an electric field strength of 500-1500 V / cm for 5-200 minutes.

[0049] According to the present invention, preferably, in S2, the membrane separation process includes: passing the reacted decalcifying agent aqueous solution through a nanofiltration membrane for at least one stage of nanofiltration treatment to obtain a concentrated solution and a filtrate of the reaction product of the calcium ions and the decalcifying agent, and then passing the filtrate through a reverse osmosis membrane for at least one stage of reverse osmosis treatment to obtain the first sodium ion-containing concentrated solution and the fresh water.

[0050] After nanofiltration treatment, the compound formed after the reaction of calcium ions and the decalcifying agent is retained by the nanofiltration membrane to form a concentrated solution of the reaction product of calcium ions and the decalcifying agent; sodium ions and water selectively pass through the nanofiltration membrane to form a filtrate containing sodium ions.

[0051] According to the present invention, preferably, the nanofiltration pressure is 0.2-2 MPa. When the nanofiltration pressure is 0.2-2 MPa, the nanofiltration is performed using cross-flow filtration, and the filtrate recovery rate is 50-85%. The filtrate recovery rate is related to the calcium ion concentration in the hydrocarbon oil, and the filtrate recovery rate decreases as the calcium ion concentration increases.

[0052] According to the present invention, preferably, the nanofiltration membrane is selected from a monovalent ion selective nanofiltration membrane, which has a retention rate of 95-99% for calcium and magnesium ions and a retention rate of 1-10% for sodium ions.

[0053] According to the present invention, preferably, the nanofiltration membrane is selected from a rolled nanofiltration membrane, a tubular nanofiltration membrane, a hollow fiber nanofiltration membrane or a plate nanofiltration membrane, preferably a rolled nanofiltration membrane or a tubular nanofiltration membrane.

[0054] According to the present invention, preferably, the material of the nanofiltration membrane is selected from at least one of aromatic polyamide, polypiperazineamide, cellulose acetate and sulfonated polyethersulfone, preferably aromatic polyamide.

[0055] According to the present invention, reverse osmosis treatment is performed using a reverse osmosis pressure greater than the osmotic pressure of the filtrate. Preferably, the reverse osmosis treatment pressure is 2-6 MPa. When the reverse osmosis treatment pressure meets 2-6 MPa, a single-stage reverse osmosis treatment is performed using cross-flow filtration, resulting in a sodium salt retention rate of 97-98% and a fresh water recovery rate of 75-85%.

[0056] According to the present invention, preferably, the reverse osmosis membrane is a plate reverse osmosis membrane, a tubular reverse osmosis membrane or a spiral reverse osmosis membrane, preferably a spiral reverse osmosis membrane.

[0057] According to the present invention, preferably, the material of the reverse osmosis membrane is selected from at least one of aromatic polyamide, polypiperazineamide, polyimide and sulfonated polysulfone, preferably polypiperazineamide.

[0058] According to a preferred embodiment of the present invention, the decalcifying agent aqueous solution after the reaction is subjected to a two-stage nanofiltration treatment, and the filtrate is subjected to a single-stage reverse osmosis treatment. The first-stage nanofiltration treatment is performed using a tubular nanofiltration membrane made of aromatic polyamide, the second-stage nanofiltration treatment is performed using a spiral nanofiltration membrane made of aromatic polyamide, and the reverse osmosis treatment is performed using a spiral reverse osmosis membrane made of polypiperazineamide.

[0059] For calcium-containing hydrocarbon oils with a high sodium chloride content, the Na ion content in the post-reaction decalcification agent aqueous solution obtained after the electrical desalination treatment is also high. The inventors have found that for the post-reaction decalcification agent aqueous solution with a high Na ion content obtained after the electrical desalination treatment, especially the post-reaction decalcification agent aqueous solution with a Na content greater than or equal to 200 μg / g, a two-stage nanofiltration treatment is performed, and both stages of nanofiltration treatment use nanofiltration membranes made of aromatic polyamide, wherein the first-stage nanofiltration treatment uses a tubular nanofiltration membrane and the second-stage nanofiltration treatment uses a roll nanofiltration membrane, and then the obtained filtrate is subjected to reverse osmosis treatment by a roll reverse osmosis membrane made of polypiperazineamide. This can remove metal ions such as Ca, Mg and Na in the water, especially the removal of Na, eliminate the influence of water-soluble sodium salts on the electrical desalination of crude oil, achieve complete regeneration of decalcification wastewater and carry out long-term recycling, and can well realize the resource utilization of decalcification wastewater.

[0060] According to the present invention, preferably, the membrane separation process further comprises: pre-treating the decalcifying agent aqueous solution after the reaction before performing the nanofiltration treatment. The purpose of the pre-treatment is to remove suspended matter, sediment and other impurities in the decalcifying agent aqueous solution after the reaction.

[0061] According to the present invention, preferably, the pretreatment method comprises: subjecting the reacted decalcifying agent aqueous solution to microfiltration treatment through a microfiltration membrane.

[0062] According to the present invention, preferably, the microfiltration membrane is selected from one or two of the average pore size (filtration accuracy) of 0.1-0.5 μm, 0.5-1 μm, 1-5 μm and 5-10 μm, and the microfiltration purification system can be a combination of microfiltration membranes with different average pore sizes.

[0063] According to the present invention, preferably, the material of the microfiltration membrane is selected from at least one of ceramics, polypropylene, polycarbonate, polyvinyl chloride, polysulfone, polyvinylidene fluoride and polytetrafluoroethylene.

[0064] According to the present invention, preferably, in S4, the evaporation temperature is 120-200°C, and the condensation temperature is 20-50°C.

[0065] According to the present invention, preferably, the sodium salt content in the second sodium ion-containing concentrate is 10-30 wt %. The second sodium ion-containing concentrate with a sodium salt content of 10-30 wt % can be used as a drilling fluid product.

[0066] According to the present invention, preferably, the method further comprises: washing, separating and drying the solid phase product obtained from the first precipitation reaction to obtain a calcium salt product. The specific steps are:

[0067] The solid phase product (calcium salt slag) obtained by the first precipitation reaction is washed with water at 20-50° C. until the pH value of the washed water reaches 6-7, and the washing is stopped; the slag is then separated by static sedimentation, centrifugation, or use of a filter at 20-50° C. and a pressure of -0.1 MPa to 1 MPa, and the slag is dried at 100-200° C. until the moisture content is less than or equal to 1 wt %, thereby obtaining a calcium salt product.

[0068] According to the present invention, preferably, the method further comprises: washing, separating and drying the solid phase product obtained from the second precipitation reaction to obtain a barium salt product. The specific steps are:

[0069] The solid phase product (barium salt slag) obtained by the second precipitation reaction is washed with water at 20-50° C. until the pH value of the washed water reaches 6-7, and the washing is stopped; the solid phase product (barium salt slag) is then separated by static sedimentation, centrifugation, or use of a filter at 20-50° C. and a pressure of -0.1 MPa to 1 MPa, and is then dried at 100-200° C. until the moisture content is less than or equal to 1 wt %, thereby obtaining a barium salt product.

[0070] A second aspect of the present invention provides a device for removing metal ions from hydrocarbon oil, wherein the device comprises:

[0071] an electric desalting unit for conducting an electric desalting treatment on hydrocarbon oil and a decalcifying agent aqueous solution to remove metal ions in the hydrocarbon oil;

[0072] a membrane separation unit, used for performing membrane separation on the water phase flowing out of the electrical desalination unit;

[0073] an evaporation and condensation unit, used for evaporating and concentrating the sodium ion concentrate flowing out of the membrane separation unit, and condensing the obtained gas phase product into condensed water;

[0074] The decalcification treatment unit is used to decalcify the concentrated liquid of the reaction product of calcium ions flowing out of the membrane separation unit and the decalcification agent, and mix the obtained liquid product, the fresh water flowing out of the membrane separation unit and the condensed water flowing out of the evaporation and condensation unit and return them to the electric desalination unit.

[0075] According to the present invention, preferably, the electric desalination unit comprises a mixer and an electric desalination tank that are connected. Preferably, the mixer is a mixing valve, a static mixer or an ultrasonic mixer.

[0076] According to the present invention, preferably, the membrane separation unit comprises: a nanofiltration system for nanofiltration treatment of the aqueous phase flowing out of the electrical desalination unit; and a reverse osmosis system for reverse osmosis treatment of the filtrate flowing out of the nanofiltration system.

[0077] In the present invention, the membrane separation unit includes at least one nanofiltration system, preferably two stages. When the membrane separation unit includes two nanofiltration systems, each nanofiltration system can produce corresponding filtrate and concentrate. The first-stage filtrate is sent to the raw liquid pool of the second-stage nanofiltration system for secondary nanofiltration treatment; the second-stage concentrate is returned to the raw liquid pool of the first-stage nanofiltration system for circulation. The first-stage concentrate is a concentrate containing metallic calcium salts, and a portion is discharged to the decalcification treatment unit. The second-stage filtrate is a filtrate containing metallic sodium salts.

[0078] According to the present invention, preferably, the membrane separation unit further comprises a microfiltration purification system for removing suspended matter and sediment from the water phase flowing out of the electric desalination unit and feeding the water phase into the nanofiltration system.

[0079] According to the present invention, preferably, the microfiltration membrane is selected from one or two of the group consisting of an average pore size (filtration accuracy) of 0.1-0.5 μm, 0.5-1 μm, 1-5 μm, and 5-10 μm. In the present invention, the membrane separation unit includes at least one stage of microfiltration purification system, which may be a combination of microfiltration purification systems having different average pore sizes of microfiltration membranes.

[0080] According to the present invention, preferably, the evaporation-condensation unit includes an evaporator and a condenser that are connected.

[0081] According to the present invention, preferably, the decalcification treatment unit includes:

[0082] a first solidification reaction tank, configured to mix the concentrated reaction product of the calcium ions flowing out of the nanofiltration system and the decalcifying agent with a first precipitant to perform a first precipitation reaction;

[0083] a first solid-liquid separator, for performing a first solid-liquid separation on the liquid flowing out of the first solidification reaction tank;

[0084] a second solidification reaction tank, configured to mix the liquid product flowing out of the first solid-liquid separator with a second precipitant to perform a second precipitation reaction;

[0085] The second solid-liquid separator is used to perform a second solid-liquid separation on the material flowing out of the second solidification reaction tank, and the obtained liquid phase product, the condensed water flowing out of the condenser and the fresh water flowing out of the reverse osmosis system are mixed through the hydrocarbon oil decalcification agent aqueous solution tank and then flow into the mixer.

[0086] According to the present invention, preferably, the decalcification treatment unit further includes: a first drying system for drying the solid phase product flowing out of the first solid-liquid separator to obtain a calcium salt product; and a second drying system for drying the solid phase product flowing out of the second solid-liquid separator to obtain a barium salt product.

[0087] According to a specific embodiment of the present invention, the method for removing metal ions from hydrocarbon oil in the apparatus shown in FIG1 comprises the following steps:

[0088] S1. Mixing a hydrocarbon oil decalcifying agent and water (based on the weight of the hydrocarbon oil, the contents of the hydrocarbon oil decalcifying agent and water are 0.01-5 wt% and 1-25 wt%, respectively) to obtain a decalcifying agent aqueous solution; thoroughly mixing the decalcifying agent aqueous solution and hydrocarbon oil 1 using a mixer 2 at a mixing pressure difference of 0.02-1 MPa at 50-150° C., controlling the diameter of the oil and water particles to be within the range of 0.1-50 μm; then placing the oil-water mixture in an electric desalting tank 3, holding it at a temperature of 50-150° C. and an electric field strength of 50-500 V / cm for 1-60 minutes, and then holding it at a temperature of 50-150° C. and an electric field strength of 500-1500 V / cm for 5-200 minutes; after oil and water separation, obtaining demetallized hydrocarbon oil 4 and reacted decalcifying agent aqueous solution 5;

[0089] S2, the post-reaction decalcifying agent aqueous solution 5 obtained in S1 is pretreated by a microfiltration purification system 6 to remove suspended matter, silt and other impurities therein; the pretreated filtrate 7 is sent to a nanofiltration system 8 (using a monovalent ion selective permeable nanofiltration membrane) for treatment at a treatment pressure of 0.2-2 MPa, and divalent calcium and magnesium ions are separated from monovalent sodium ions by cross-flow filtration to obtain a sodium ion-containing filtrate 10 and a concentrated solution 9 of the reaction product of calcium ions and the decalcifying agent; the obtained sodium ion-containing filtrate 10 is sent to a reverse osmosis system 11 for reverse osmosis treatment, and the operating pressure of the reverse osmosis system is 2-6 MPa to obtain fresh water 12 free of metal salts and a first sodium ion-containing concentrated solution 13;

[0090] In S3, in the first solidification reaction tank 20, the concentrated solution 9 of the reaction product of calcium ions and the decalcifying agent flowing out of the nanofiltration system in S2 is subjected to a first precipitation reaction with sulfuric acid flowing out of the first precipitant storage tank 18 (the amount of sulfuric acid used is the theoretical amount of sulfuric acid when the calcium ions in the concentrated solution of the reaction product of calcium ions and the decalcifying agent are completely reacted), the reaction temperature is 20-50°C, the time is 5-30min, and a feed solution 21 containing calcium sulfate precipitate is generated; under the conditions of a temperature of 20-50°C and a pressure of -0.1MPa to 1MPa, a first solid-liquid separation is performed using a first solid-liquid separator 22 (centrifuge, speed of 2500-3500r / min) to obtain a first recovered concentrated water 23 and a calcium sulfate solid residue, and the first recovered concentrated water 23 is discharged into the second solidification reaction tank 27; in the second solidification reaction tank 27, the first recovered concentrated water 2 3 is subjected to a second precipitation reaction with the barium chloride flowing out of the second precipitant storage tank 19 (the amount of barium chloride used is the theoretical amount of barium chloride required for complete reaction with the sulfate radicals contained in the first recovered concentrated water), the reaction temperature is 20-50° C., and the reaction time is 5-30 minutes, to generate a feed solution 28 containing barium sulfate precipitate; under the conditions of a temperature of 20-50° C. and a pressure of -0.1 MPa to 1 MPa, a second solid-liquid separation is performed using a second solid-liquid separator 29 (centrifuge, speed of 2500-3500 r / min) to obtain a second recovered concentrated water 33 (decalcified decalcifying agent concentrate) and a barium sulfate solid residue, and the second recovered concentrated water is discharged into a hydrocarbon oil decalcifying agent aqueous solution tank 34; wherein the obtained calcium sulfate solid residue and barium sulfate solid residue are respectively washed, separated, and dried to obtain a calcium sulfate product and a barium sulfate product, respectively, and the specific steps include:

[0091] Under the condition of 20-50° C., the calcium sulfate solid slag is washed with water in a calcium salt slag tank 24 (with the weight of the calcium sulfate solid slag as the benchmark, the amount of water is 50-200wt%), allowed to stand for stratification, and repeatedly washed with water until the pH value of the wash water is 6-7; the washing is stopped; under the condition of 20-50° C. and −0.1 MPa to 1 MPa, the separated calcium slag is dried in a first drying system 25 at 100-200° C. to a moisture content of less than or equal to 1wt%, to obtain a calcium sulfate product 26;

[0092] The barium sulfate solid slag is washed with water in a barium salt slag tank 30 at 20-50° C. (the amount of water is 50-200 wt % based on the weight of the barium sulfate solid slag), allowed to stand for stratification, and repeatedly washed with water until the pH value of the washing water reaches 6-7. The barium sulfate solid slag is allowed to stand for stratification at 20-50° C. and a pressure of -0.1 MPa to 1 MPa, and the separated barium slag is dried in a second drying system 31 at 100-200° C. until the moisture content is less than or equal to 1 wt %, thereby obtaining a barium sulfate product 32.

[0093] S4. In the evaporation and condensation unit 14, the first sodium ion-containing concentrated solution 13 obtained in S2 is evaporated and concentrated at 120-200° C. and condensed at 20-50° C. to obtain a second sodium ion-containing concentrated solution 15 and evaporated condensed water 16. The obtained second sodium ion-containing concentrated solution 15 is stored in a brine storage tank 17. The evaporated condensed water, the second recovered concentrated water 33 obtained in S3 (decalcified decalcifying agent concentrated solution), and the metal salt-free fresh water 12 obtained in S2 are mixed in a hydrocarbon oil decalcifying agent aqueous solution tank 34 to obtain a recovered aqueous solution 35 containing hydrocarbon oil decalcifying agent. When the concentration of hydrocarbon oil decalcifying agent in the recovered aqueous solution is higher than the required ratio of decalcifying agent to hydrocarbon oil, a certain amount of water 36 is added until the concentration of hydrocarbon oil decalcifying agent in the aqueous solution meets the required ratio of hydrocarbon oil decalcifying agent to hydrocarbon oil, after which the aqueous solution is returned to S1 for recycling.

[0094] The present invention will be described in detail below through examples and comparative examples. In the following examples and comparative examples, unless otherwise specified, conventional methods are used; the reagents and materials used, unless otherwise specified, can be obtained from commercial sources. The test methods involved in the following examples and comparative examples are as follows:

[0095] Analysis method for metal ions in hydrocarbon oil: RIPP124-1990 plasma emission spectrometry;

[0096] Analysis method for metal ions in water: RIPP124-1990 plasma emission spectrometry;

[0097] Analysis method for sulfate ions in water: GB 11899 Water quality, Determination of sulfate, gravimetric method;

[0098] Analysis method for phosphate ions in water: GB / T14642-2009 Determination of fluoride, chlorine, phosphate, nitrite, nitrate and sulfate in industrial circulating cooling water and boiler water, ion chromatography;

[0099] Analysis method of decalcifying agent concentration: liquid chromatography.

[0100] The following examples are used to illustrate the method for demetallizing hydrocarbon oil and resource utilization of decalcified wastewater according to the flow chart shown in FIG1 .

[0101] Example 1

[0102] The hydrocarbon oil to be treated in this embodiment is a minus four fraction oil, and the metal ion contents are as follows: calcium ion 40.4 μg / g, magnesium ion 5.13 μg / g, and sodium ion 2.8 μg / g.

[0103] Demetallization of hydrocarbon oil is carried out as follows:

[0104] S1. Mixing a hydrocarbon oil decalcifying agent (formic acid) and water (based on the weight of the oil minus the fourth distillation fraction, the contents of the hydrocarbon oil decalcifying agent and water are 0.01 wt% and 25 wt%, respectively) to obtain a decalcifying agent aqueous solution; fully mixing the decalcifying agent aqueous solution and the oil minus the fourth distillation fraction at 50° C. with a static mixer at a mixing pressure difference of 0.02 MPa for 1 minute; then placing the oil-water mixture in an electric desalting tank, retaining it at a temperature of 50° C. and an electric field strength of 50 V / cm for 1 minute, and then retaining it at a temperature of 50° C. and an electric field strength of 500 V / cm for 5 minutes; after oil-water separation, obtaining demetallized hydrocarbon oil and a reacted decalcifying agent aqueous solution; analysis showed that the demetallized hydrocarbon oil contained 1.5 μg / g of calcium, 0.21 μg / g of magnesium, and 0.8 μg / g of sodium; and the reacted decalcifying agent aqueous solution contained 0.02 wt% of calcium and 0.001 wt% of sodium.

[0105] S2. The decalcifying agent aqueous solution obtained in S1 is pretreated using a microfiltration purification system (composed of a two-stage microfiltration system with filtration precisions of 10 μm and 0.5 μm, respectively, with the microfiltration membranes made of polypropylene and polyvinyl chloride, respectively) to remove suspended matter, silt, and other impurities. The pretreated filtrate is sequentially sent to a primary nanofiltration system and a secondary nanofiltration system (both the two-stage nanofiltration systems use monovalent ion selective permeable nanofiltration membranes made of aromatic polyamide; the primary nanofiltration system uses a tubular nanofiltration membrane, and the secondary nanofiltration system uses a roll nanofiltration membrane) for treatment at a pressure of 0.3 MPa. Cross-flow filtration is used to separate divalent calcium and magnesium ions from monovalent sodium ions, obtaining a sodium ion-containing filtrate and a concentrated solution of the reaction product of calcium ions and the decalcifying agent. The retention rates of calcium and magnesium ions are 95%, and the retention rate of sodium ions is 10%. The recovery rate of the filtrate is 85%. The obtained sodium ion-containing filtrate was sent to a reverse osmosis system (using a spiral reverse osmosis membrane made of polypiperazineamide) for reverse osmosis treatment. The operating pressure of the reverse osmosis system was 2 MPa to obtain fresh water without metal salts and a first sodium ion-containing concentrate. The sodium salt rejection rate was 97%, and the fresh water recovery rate was 85%.

[0106] S3, in the first solidification reaction tank, the concentrated solution of the reaction product of calcium ions and the decalcifying agent flowing out of the nanofiltration system in S2 is subjected to a first precipitation reaction with sulfuric acid flowing out of the first precipitant storage tank (the amount of sulfuric acid is the theoretical amount of sulfuric acid when the calcium ions in the concentrated solution of the reaction product of calcium ions and the decalcifying agent are completely reacted), the reaction temperature is 50°C, the time is 5min, and a feed liquid containing calcium sulfate precipitate is generated; a centrifuge is used to perform a first solid-liquid separation at a speed of 3000r / min to obtain a first recovered concentrated water and a calcium sulfate solid residue, and the first recovered concentrated water is discharged to the second solidification reaction tank; in the second solidification reaction tank, the first recovered concentrated water (sulfate content The invention relates to a method for preparing a first recovered concentrated water tank comprising: performing a second precipitation reaction with barium chloride discharged from a second precipitant storage tank (the amount of barium chloride used is the theoretical amount of barium chloride required for complete reaction with sulfate ions contained in the first recovered concentrated water); and performing a second solid-liquid separation using a centrifuge at a speed of 3000 r / min to obtain a second recovered concentrated water and a barium sulfate solid residue. The second recovered concentrated water is discharged into a hydrocarbon oil decalcifying agent aqueous solution tank. The obtained calcium sulfate solid residue and barium sulfate solid residue are respectively washed, separated, and dried to obtain a calcium sulfate product and a barium sulfate product, respectively. The method comprises the following steps:

[0107] Under normal temperature, the calcium sulfate solid residue is washed with water in a calcium salt slag tank (based on the weight of the calcium sulfate solid residue, with a water consumption of 100wt%), allowed to stand for stratification, and repeatedly washed until the pH value of the wash water reaches 6, and the washing is stopped; the separated calcium residue is allowed to stand for sedimentation and stratification at normal temperature and pressure, and is dried in a first drying system at 120°C to a moisture content of less than or equal to 1wt%, to obtain a calcium sulfate product (the calcium sulfate purity is 92.7wt%, meeting the quality standard for building gypsum);

[0108] Under normal temperature conditions, the barium sulfate solid slag is washed with water in a barium salt slag tank (the amount of water is 100wt% based on the weight of the barium sulfate solid slag), allowed to stand for stratification, and repeatedly washed with water until the pH value of the washing water reaches 6; the barium slag is allowed to stand for sedimentation and stratification at normal temperature and pressure, and the separated barium slag is dried in a second drying system at 120° C. until the moisture content is less than or equal to 1wt%, thereby obtaining a barium sulfate product (barium sulfate purity is 93.1wt%, meeting the quality standard of precipitated barium sulfate);

[0109] S4. In the evaporation and condensation unit, the first sodium ion-containing concentrated solution obtained in S2 is evaporated and concentrated at 120° C. and condensed at 20° C. to obtain a second sodium ion-containing concentrated solution and evaporated condensate. The obtained second sodium ion-containing concentrated solution (having a sodium salt content of 10 wt %, meeting the quality standard for brine drilling fluid) is placed in a brine storage tank. The evaporated condensate, the second recovered concentrated water obtained in S3, and the metal salt-free fresh water obtained in S2 are mixed in a hydrocarbon oil decalcifying agent aqueous solution tank. The obtained recovered aqueous solution containing the hydrocarbon oil decalcifying agent (having a sulfate content of 83 mg / L) is returned to S1 for recycling.

[0110] Example 2

[0111] The hydrocarbon oil to be treated in this embodiment is crude oil, and the metal ion contents are as follows: calcium ion 520 μg / g, magnesium ion 5.64 μg / g, and sodium ion 120.1 μg / g.

[0112] Demetallization of hydrocarbon oil is carried out as follows:

[0113] S1. Mixing a hydrocarbon oil decalcifying agent (acetic acid) and water (based on the weight of the crude oil, the contents of the hydrocarbon oil decalcifying agent and water are 0.52 wt% and 8 wt%, respectively) to obtain a decalcifying agent aqueous solution; fully mixing the decalcifying agent aqueous solution and the crude oil with a stirrer at a temperature of 150° C. and a pressure of 1 MPa for 30 min; then placing the oil-water mixture in an electric desalting tank, retaining it at a temperature of 150° C. and an electric field strength of 500 V / cm for 60 min, and then retaining it at a temperature of 150° C. and an electric field strength of 1000 V / cm for 200 min; after oil-water separation, obtaining demetallized hydrocarbon oil and a decalcifying agent aqueous solution after reaction; analysis showed that the demetallized hydrocarbon oil had a calcium content of 13.2 μg / g, a magnesium content of 0.2 μg / g, and a sodium content of 1 μg / g; and the decalcifying agent aqueous solution after reaction had a calcium content of 0.25 wt% and a sodium content of 0.059 wt%;

[0114] S2. The decalcifying agent aqueous solution obtained after the reaction in S1 is pretreated using a microfiltration purification system (composed of a two-stage microfiltration system with filtration precisions of 5 μm and 0.1 μm, respectively, with the microfiltration membranes made of ceramic and polycarbonate, respectively) to remove suspended matter, silt, and other impurities. The pretreated filtrate is sequentially sent to a primary nanofiltration system and a secondary nanofiltration system (both the two-stage nanofiltration systems use monovalent ion selective permeable nanofiltration membranes made of aromatic polyamide; the primary nanofiltration system uses a tubular nanofiltration membrane, and the secondary nanofiltration system uses a roll nanofiltration membrane) for treatment at a treatment pressure of 2 MPa. Cross-flow filtration is used to separate divalent calcium and magnesium ions from monovalent sodium ions, obtaining a sodium ion-containing filtrate and a concentrated solution of the reaction product of calcium ions and the decalcifying agent. The retention rates of calcium and magnesium ions are 96%, and the retention rate of sodium ions is 10%. The recovery rate of the filtrate is 85%. The obtained sodium ion-containing filtrate was sent to a reverse osmosis system (using a spiral reverse osmosis membrane made of polypiperazineamide) for reverse osmosis treatment. The operating pressure of the reverse osmosis system was 2 MPa to obtain fresh water without metal salts and a first sodium ion-containing concentrate. The sodium salt rejection rate was 98%, and the fresh water recovery rate was 75%.

[0115] S3, in the first solidification reaction tank, the concentrated solution of the reaction product of calcium ions and the decalcifying agent flowing out of the nanofiltration system in S2 is subjected to a first precipitation reaction with phosphoric acid flowing out of the first precipitant storage tank (the amount of phosphoric acid used is the theoretical amount of phosphoric acid when the calcium ions in the concentrated solution of the reaction product of calcium ions and the decalcifying agent are completely reacted), the reaction temperature is 45°C, the time is 30min, and a feed liquid containing calcium phosphate precipitate is generated; under the conditions of a temperature of 45°C and a pressure of 0.15MPa, a first solid-liquid separation is performed through a filter to obtain a first recovered concentrated water and a calcium phosphate solid residue, and the first recovered concentrated water is discharged to the second solidification reaction tank; in the second solidification reaction tank, the first recovered concentrated water ( The invention relates to a method for preparing a first recovered concentrated water having a phosphate content of 780 mg / L) and barium chloride discharged from a second precipitant storage tank for a second precipitation reaction (the amount of barium chloride used is the theoretical amount of barium chloride required for complete reaction with the phosphate contained in the first recovered concentrated water), the reaction temperature being 45° C. and the reaction time being 30 min to generate a feed liquid containing barium phosphate precipitate; a second solid-liquid separation is performed using a centrifuge at a speed of 3000 r / min to obtain a second recovered concentrated water and a barium phosphate solid residue, and the second recovered concentrated water is discharged into a hydrocarbon oil decalcifying agent aqueous solution tank; wherein the obtained calcium phosphate solid residue and barium phosphate solid residue are respectively washed, separated and dried to obtain a calcium phosphate product and a barium phosphate product, respectively. The method specifically comprises the following steps:

[0116] The calcium phosphate solid residue is washed with water in a calcium salt slag tank at room temperature (with water consumption of 160 wt % based on the weight of the calcium phosphate solid residue), allowed to stand for stratification, and repeatedly washed until the pH value of the wash water reaches 7; the calcium phosphate solid residue is allowed to stand for sedimentation and stratification at room temperature and pressure, and the separated calcium slag is dried in a first drying system at 120° C. until the moisture content is less than or equal to 1 wt %, thereby obtaining a calcium phosphate product (calcium phosphate purity is 93.1 wt %, meeting the quality standard of building materials);

[0117] Under normal temperature conditions, the barium phosphate solid slag is washed with water in a barium salt slag tank (the amount of water is 160wt% based on the weight of the barium phosphate solid slag), allowed to stand for stratification, and repeatedly washed with water until the pH value of the washing water reaches 7; the barium phosphate solid slag is allowed to stand for sedimentation and stratification at normal temperature and pressure, and the separated barium slag is dried in a second drying system at 120° C. until the moisture content is less than or equal to 1wt%, thereby obtaining a barium phosphate product (barium phosphate purity is 95.7wt%);

[0118] S4. In the evaporation and condensation unit, the first sodium ion-containing concentrated solution obtained in S2 is evaporated and concentrated at 200° C. and condensed at 50° C. to obtain a second sodium ion-containing concentrated solution and evaporated condensate. The obtained second sodium ion-containing concentrated solution (having a sodium salt content of 30 wt %, meeting the quality standard for brine drilling fluid) is placed in a brine storage tank. The evaporated condensate, the second recovered concentrated water obtained in S3, and the fresh water free of metal salts obtained in S2 are mixed in a hydrocarbon oil decalcifying agent aqueous solution tank. The obtained recovered aqueous solution containing the hydrocarbon oil decalcifying agent (with a phosphate content of 55 mg / L) is returned to S1 for recycling.

[0119] Example 3

[0120] The hydrocarbon oil to be treated in this embodiment is thick oil, and the metal ion contents are as follows: calcium ion 712 μg / g, magnesium ion 2.53 μg / g, and sodium ion 95.8 μg / g.

[0121] Demetallization of hydrocarbon oil is carried out as follows:

[0122] S1. Mixing a hydrocarbon oil decalcifying agent (propionic acid) and water (based on the weight of the heavy oil, the contents of the hydrocarbon oil decalcifying agent and water are 0.25 wt % and 20 wt %, respectively) to obtain a decalcifying agent aqueous solution; shearing the decalcifying agent aqueous solution and the heavy oil with an emulsifying shearing instrument for 15 min at a temperature of 120° C. and a pressure of 0.5 MPa; then placing the oil-water mixture in an electric desalting tank, leaving it for 30 min at a temperature of 120° C. and an electric field strength of 400 V / cm, and then leaving it for 150 min at a temperature of 120° C. and an electric field strength of 1500 V / cm; after oil-water separation, obtaining demetallized hydrocarbon oil and a decalcifying agent aqueous solution after reaction; analyzing the hydrocarbon oil after demetallization to obtain a calcium content of 25.8 μg / g, a magnesium content of 0.35 μg / g, and a sodium content of 1.3 μg / g; and the calcium content of the decalcifying agent aqueous solution after reaction was 0.34 wt % and 0.047 wt %;

[0123] S2. The decalcifying agent aqueous solution obtained after the reaction in S1 is pretreated using a microfiltration purification system (composed of a two-stage microfiltration system with filtration precisions of 5 μm and 0.1 μm, respectively, with the microfiltration membranes made of polypropylene and polysulfone, respectively) to remove suspended matter, silt, and other impurities. The pretreated filtrate is sequentially sent to a primary nanofiltration system and a secondary nanofiltration system (both the two-stage nanofiltration systems use monovalent ion selective permeable nanofiltration membranes made of aromatic polyamide; the primary nanofiltration system uses a tubular nanofiltration membrane, and the secondary nanofiltration system uses a roll nanofiltration membrane) for treatment at a treatment pressure of 0.2 MPa. Cross-flow filtration is used to separate divalent calcium and magnesium ions from monovalent sodium ions, obtaining a sodium ion-containing filtrate and a concentrated solution of the reaction product of calcium ions and the decalcifying agent. The retention rates of calcium and magnesium ions are 99%, and the retention rate of sodium ions is 1%. The recovery rate of the filtrate is 84%. The obtained sodium ion-containing filtrate was sent to a reverse osmosis system (using a spiral reverse osmosis membrane made of polypiperazineamide) for reverse osmosis treatment. The operating pressure of the reverse osmosis system was 4 MPa to obtain fresh water without metal salts and a first sodium ion-containing concentrate. The sodium salt rejection rate was 97%, and the fresh water recovery rate was 80%.

[0124] S3, in the first solidification reaction tank, the concentrated solution of the reaction product of calcium ions and the decalcifying agent flowing out of the nanofiltration system in S2 is subjected to a first precipitation reaction with sulfuric acid flowing out of the first precipitant storage tank (the amount of sulfuric acid used is the theoretical amount of sulfuric acid when the calcium ions in the concentrated solution of the reaction product of calcium ions and the decalcifying agent are completely reacted), the reaction temperature is 30°C, the time is 10min, and a feed liquid containing calcium sulfate precipitate is generated; a first solid-liquid separation is performed with a suction filter under the conditions of a temperature of 30°C and a pressure of -0.08MPa to obtain a first recovered concentrated water and a calcium sulfate solid residue, and the first recovered concentrated water is discharged into the second solidification reaction tank; in the second solidification reaction tank, the first recovered concentrated water ( The invention relates to a method for preparing a first recovered concentrated water having a sulfate content of 1180 mg / L) and barium chloride discharged from a second precipitant storage tank for a second precipitation reaction (the amount of barium chloride used is the theoretical amount of barium chloride required for complete reaction with the sulfate contained in the first recovered concentrated water), the reaction temperature being 20° C. and the reaction time being 20 minutes, to generate a feed solution containing barium sulfate precipitate; a second solid-liquid separation is performed using a centrifuge at a speed of 3000 r / min to obtain a second recovered concentrated water and a barium sulfate solid residue, and the second recovered concentrated water is discharged into a hydrocarbon oil decalcifying agent aqueous solution tank; wherein the obtained calcium sulfate solid residue and barium sulfate solid residue are respectively washed, separated and dried to obtain a calcium sulfate product and a barium sulfate product, respectively. The method specifically comprises the following steps:

[0125] Under normal temperature conditions, the calcium sulfate solid residue is washed with water in a calcium salt slag tank (with the weight of the calcium sulfate solid residue as the benchmark, the amount of water is 200wt%), allowed to stand for stratification, and repeatedly washed with water until the pH value of the wash water reaches 6.2, and the washing is stopped; the separated calcium residue is allowed to stand for sedimentation and stratification at normal temperature and pressure, and is dried in a first drying system at 120°C to a moisture content of less than or equal to 1wt%, to obtain a calcium sulfate product (the purity of the calcium sulfate is 92.7wt%, meeting the quality standard for building gypsum);

[0126] Under normal temperature conditions, the barium sulfate solid slag is washed with water (based on the weight of the barium sulfate solid slag, the amount of water is 200wt%; based on the weight of the barium sulfate solid slag), allowed to stand for stratification, and repeatedly washed with water until the pH value of the washing water reaches 6.2; the barium slag is allowed to stand for sedimentation and stratification at normal temperature and pressure, and the separated barium slag is dried in a second drying system at 120° C. until the moisture content is less than or equal to 1wt%, thereby obtaining a barium sulfate product (barium sulfate purity is 94.1wt%, meeting the quality standard of precipitated barium sulfate);

[0127] S4. In the evaporation and condensation unit, the first sodium ion-containing concentrated solution obtained in S2 is evaporated and concentrated at 160° C. and condensed at 40° C. to obtain a second sodium ion-containing concentrated solution and evaporated condensate. The obtained second sodium ion-containing concentrated solution (having a sodium salt content of 20 wt %, meeting the quality standard for brine drilling fluid) is placed in a brine storage tank. The evaporated condensate, the second recovered concentrated water obtained in S3, and the fresh water free of metal salts obtained in S2 are mixed in a hydrocarbon oil decalcifying agent aqueous solution tank. The obtained recovered aqueous solution containing the hydrocarbon oil decalcifying agent (having a sulfate content of 46 mg / L) is returned to S1 for recycling.

[0128] Example 4

[0129] The hydrocarbon oil to be treated in this embodiment is extra-heavy oil, and the metal ion contents are as follows: calcium ion 1380 μg / g, magnesium ion 14.32 μg / g, and sodium ion 282 μg / g.

[0130] Demetallization of hydrocarbon oil is carried out as follows:

[0131] S1. Mixing a hydrocarbon oil decalcifying agent (butyric acid) and water (based on the weight of the super heavy oil, the contents of the hydrocarbon oil decalcifying agent and water are 1.38 wt% and 15 wt%, respectively) to obtain a decalcifying agent aqueous solution; fully mixing the decalcifying agent aqueous solution and the super heavy oil in a membrane reactor using a metal membrane with a pore size of 10 μm as a membrane material at a temperature of 150° C. and a pressure of 0.3 MPa; then placing the oil-water mixture in an electric desalting tank and heating the mixture at a temperature of 150° C. and an electric field strength of 0.5 μm. The reaction mixture was heated at an electric field strength of 300 V / cm for 20 minutes, and then heated at a temperature of 150°C and an electric field strength of 1400 V / cm for 90 minutes. After oil-water separation, a demetallized hydrocarbon oil and a decalcifying agent aqueous solution after the reaction were obtained. Analysis showed that the demetallized hydrocarbon oil contained 37.8 μg / g of calcium, 0.78 μg / g of magnesium, and 1.5 μg / g of sodium. The decalcifying agent aqueous solution after the reaction contained 0.67 wt% of calcium and 0.14 wt% of sodium.

[0132] S2. The decalcifying agent aqueous solution obtained in S1 was pretreated using a microfiltration purification system (composed of a two-stage microfiltration system with filtration accuracies of 10 μm and 1 μm, respectively, with the microfiltration membranes made of polyvinylidene fluoride and polypropylene, respectively) to remove suspended matter, silt, and other impurities. The pretreated filtrate was sequentially sent to a primary nanofiltration system and a secondary nanofiltration system (both nanofiltration systems used monovalent ion selective permeable nanofiltration membranes made of aromatic polyamide; the primary nanofiltration system used a tubular nanofiltration membrane, and the secondary nanofiltration system used a roll nanofiltration membrane) for treatment at a pressure of 0.3 MPa. Cross-flow filtration was used to separate divalent calcium and magnesium ions from monovalent sodium ions, obtaining a sodium ion-containing filtrate and a concentrated solution of the reaction product of calcium ions and the decalcifying agent. The retention rates of calcium and magnesium ions were 96%, and the retention rate of sodium ions was 7%. The recovery rate of the filtrate was 75%. The obtained sodium ion-containing filtrate was sent to a reverse osmosis system (using a spiral reverse osmosis membrane made of polypiperazineamide) for reverse osmosis treatment. The operating pressure of the reverse osmosis system was 6 MPa to obtain fresh water without metal salts and a first sodium ion-containing concentrate. The sodium salt rejection rate was 98%, and the fresh water recovery rate was 78%.

[0133] In S3 and the first solidification reaction tank, the concentrated solution of the reaction product of calcium ions and the decalcifying agent discharged from the nanofiltration system in S2 is subjected to a first precipitation reaction with sulfuric acid discharged from the first precipitant storage tank (the amount of sulfuric acid is the theoretical amount of sulfuric acid when the calcium ions in the concentrated solution of the reaction product of calcium ions and the decalcifying agent are completely reacted), the reaction temperature is 30° C., and the time is 15 min to generate a feed liquid containing calcium sulfate precipitate; under the condition of a pressure of 0.02 MPa, a cyclone separator is used for a first solid-liquid separation to obtain a first recovered concentrated water and a calcium sulfate solid residue, and the first recovered concentrated water is discharged to the second solidification reaction tank; in the second solidification reaction tank, the first recovered concentrated water (sulfate content The method comprises the following steps: performing a second precipitation reaction on the barium acetate discharged from the second precipitant storage tank (the amount of barium acetate used is the theoretical amount of barium acetate when the barium acetate completely reacts with the sulfate radical contained in the first recovered concentrated water) at a temperature of 20° C. for 20 min to generate a feed solution containing barium sulfate precipitate; performing a second solid-liquid separation in a cyclone separator under a pressure of 0.02 MPa to obtain a second recovered concentrated water and a barium sulfate solid residue, and discharging the second recovered concentrated water into a hydrocarbon oil decalcifying agent aqueous solution tank; washing, separating and drying the obtained calcium sulfate solid residue and barium sulfate solid residue to obtain a calcium sulfate product and a barium sulfate product, respectively.

[0134] Under normal temperature, the calcium sulfate solid residue is washed with water in a calcium salt slag tank (with the weight of the calcium sulfate solid residue as a benchmark, the consumption of water is 150wt%), allowed to stand for stratification, and repeatedly washed with water until the pH value of the wash water reaches 7, and the washing is stopped; the temperature is 30°C, and the pressure is -0.5MPa, and suction filtration is carried out under the condition of the isolated calcium residue being dried at 150°C to a moisture content of less than or equal to 1wt% in a first drying system to obtain a calcium sulfate product (the calcium sulfate purity is 94.3wt%, which meets the building gypsum quality standard);

[0135] Under normal temperature conditions, the barium sulfate solid residue is washed with water in a barium salt slag tank (the amount of water is 150wt% based on the weight of the barium sulfate solid residue), allowed to stand for stratification, and repeatedly washed with water until the pH value of the washing water reaches 7; the washing is stopped; and the separated barium residue is filtered through a hydrocyclone separator under a pressure of 0.02Mpa, and the separated barium residue is dried at 110°C in a second drying system to a moisture content of less than or equal to 1wt%, thereby obtaining a barium sulfate product (barium sulfate purity is 93.7wt%, meeting the quality standard of precipitated barium sulfate);

[0136] S4, in the evaporation and condensation unit, the first sodium ion-containing concentrated solution obtained in S2 is evaporated and concentrated at 120° C. and condensed at 30° C. to obtain a second sodium ion-containing concentrated solution and evaporated condensate. The obtained second sodium ion-containing concentrated solution (having a sodium salt content of 30 wt %, meeting the quality standard for brine drilling fluid) is placed in a brine storage tank; the evaporated condensate, the second recovered concentrated water obtained in S3, and the fresh water free of metal salts obtained in S2 are mixed in a hydrocarbon oil decalcifying agent aqueous solution tank, and the obtained recovered aqueous solution containing the hydrocarbon oil decalcifying agent (sulfate content of 45 mg / L) is returned to S1 for recycling.

[0137] Example 5

[0138] The hydrocarbon oil to be treated in this embodiment is waste oil, and the metal ion contents are as follows: calcium ion 27.3 μg / g, magnesium ion 0.32 μg / g, and sodium ion 0.8 μg / g.

[0139] Demetallization of hydrocarbon oil is carried out as follows:

[0140] S1. Mixing a hydrocarbon oil decalcifying agent (acetic acid) and water (based on the weight of the waste oil, the contents of the hydrocarbon oil decalcifying agent and water are 0.01wt% and 1wt%, respectively) to obtain a decalcifying agent aqueous solution; fully mixing the decalcifying agent aqueous solution and the waste oil with a stirrer at a temperature of 50° C. and a pressure of 0.02 MPa for 15 minutes; then placing the oil-water mixture in an electric desalting tank, leaving it at a temperature of 50° C. and an electric field strength of 50 V / cm for 20 minutes, and then leaving it at a temperature of 50° C. and an electric field strength of 500 V / cm for 50 minutes; after oil-water separation, obtaining demetalized hydrocarbon oil and a decalcifying agent aqueous solution after reaction; analyzing the demetalized hydrocarbon oil to obtain a calcium content of 0.5 μg / g, a magnesium content of 0.2 μg / g, and a sodium content of 0.5 μg / g; and the calcium content of the decalcifying agent aqueous solution after reaction was 0.014wt% and 0.0002wt%;

[0141] S2. The decalcifying agent aqueous solution obtained after the reaction in S1 was pretreated using a microfiltration purification system (composed of a two-stage microfiltration system with filtration precisions of 8 μm and 0.4 μm, respectively, with the microfiltration membranes made of polycarbonate and polytetrafluoroethylene, respectively) to remove suspended matter, silt, and other impurities. The pretreated filtrate was sequentially sent to a primary nanofiltration system and a secondary nanofiltration system (both the two-stage nanofiltration systems used monovalent ion selective permeable nanofiltration membranes made of aromatic polyamide; the primary nanofiltration system used a tubular nanofiltration membrane, and the secondary nanofiltration system used a roll nanofiltration membrane) for treatment at a pressure of 1.8 MPa. Cross-flow filtration was used to separate divalent calcium and magnesium ions from monovalent sodium ions, obtaining a sodium ion-containing filtrate and a concentrated solution of the reaction product of calcium ions and the decalcifying agent. The retention rates of calcium and magnesium ions were 96%, and the retention rate of sodium ions was 2%. The recovery rate of the filtrate was 83%. The obtained sodium ion-containing filtrate was sent to a reverse osmosis system (using a spiral reverse osmosis membrane made of polypiperazineamide) for reverse osmosis treatment. The operating pressure of the reverse osmosis system was 6 MPa to obtain fresh water without metal salts and a first sodium ion-containing concentrate. The sodium salt rejection rate was 97%, and the fresh water recovery rate was 85%.

[0142] S3, in the first solidification reaction tank, the concentrated solution of the reaction product of calcium ions and the decalcifying agent flowing out of the nanofiltration system in S2 is subjected to a first precipitation reaction with sulfuric acid flowing out of the first precipitant storage tank (the amount of sulfuric acid is the theoretical amount of sulfuric acid when the calcium ions in the concentrated solution of the reaction product of calcium ions and the decalcifying agent are completely reacted), and the reaction is carried out at room temperature for 5 minutes to generate a feed liquid containing calcium sulfate precipitate; a centrifuge is used to perform a first solid-liquid separation at a speed of 3000r / min to obtain a first recovered concentrated water and a calcium sulfate solid residue, and the first recovered concentrated water is discharged to the second solidification reaction tank; in the second solidification reaction tank, the first recovered concentrated water (sulfate content is The invention relates to a method for preparing a first recovered concentrated water containing barium sulfate, wherein the first recovered concentrated water contains barium acetate, 1710 mg / L of barium acetate, and barium acetate discharged from a second precipitant storage tank for a second precipitation reaction (the amount of barium acetate used is the theoretical amount of barium acetate required for complete reaction with sulfate radicals contained in the first recovered concentrated water), reacting at room temperature for 30 minutes to generate a feed liquid containing barium sulfate precipitate; performing a second solid-liquid separation using a centrifuge at a speed of 3000 r / min to obtain a second recovered concentrated water and a barium sulfate solid residue, and discharging the second recovered concentrated water into a hydrocarbon oil decalcifying agent aqueous solution tank; wherein the obtained calcium sulfate solid residue and barium sulfate solid residue are respectively washed, separated, and dried to obtain a calcium sulfate product and a barium sulfate product, respectively, which specifically comprises the following steps:

[0143] Under 25 ℃ of conditions, the calcium sulfate solid residue is washed with water in a calcium salt slag tank (with the weight of the calcium sulfate solid residue as a benchmark, the consumption of water is 50wt%), allowed to stand for stratification, and repeatedly washed with water until the pH value of the wash water reaches 6.9, and the washing is stopped; the temperature is 25 ℃, and the pressure is suction filtration under the condition of-0.75MPa, and the isolated calcium residue is dried in a first drying system at 175 ℃ to a moisture content of less than or equal to 1wt%, to obtain a calcium sulfate product (calcium sulfate purity is 98.2wt%, meeting the building gypsum quality standard);

[0144] Under normal temperature conditions, the barium sulfate solid slag is washed with water (the amount of water is 50wt% based on the weight of the barium sulfate solid slag) in a barium salt slag tank, allowed to stand for stratification, and the water washing is repeated until the pH value of the washing water reaches 7, and the water washing is stopped; the barium slag is allowed to stand for sedimentation and stratification at normal temperature and pressure, and the separated barium slag is dried in a second drying system at 120° C. until the moisture content is less than or equal to 1wt%, thereby obtaining a barium sulfate product (the purity of the barium sulfate is 95wt%, meeting the quality standard of precipitated barium sulfate);

[0145] S4. In the evaporation and condensation unit, the first sodium ion-containing concentrated solution obtained in S2 is evaporated and concentrated at 160° C. and condensed at 50° C. to obtain a second sodium ion-containing concentrated solution and evaporated condensate. The obtained second sodium ion-containing concentrated solution (having a sodium salt content of 10 wt %, meeting the quality standard for brine drilling fluid) is placed in a brine storage tank; the evaporated condensate, the second recovered concentrated water obtained in S3, and the fresh water free of metal salts obtained in S2 are mixed in a hydrocarbon oil decalcifying agent aqueous solution tank, and the obtained recovered aqueous solution containing the hydrocarbon oil decalcifying agent (having a sulfate content of 48 mg / L) is returned to S1 for recycling.

[0146] Example 6

[0147] The hydrocarbon oil to be treated in this embodiment is crude oil, and the metal ion contents are as follows: calcium ion 208 μg / g, magnesium ion 3.14 μg / g, and sodium ion 41.7 μg / g.

[0148] Demetallization of hydrocarbon oil is carried out as follows:

[0149] S1. Mixing a hydrocarbon oil decalcifying agent (acetic acid) and water (based on the weight of the crude oil, the contents of the hydrocarbon oil decalcifying agent and water are 0.07 wt% and 7 wt%, respectively) to obtain a decalcifying agent aqueous solution; fully mixing the decalcifying agent aqueous solution and the crude oil with a static mixer at a temperature of 130° C. and a pressure of 0.08 MPa for 10 minutes; then placing the oil-water mixture in an electric desalting tank, retaining it at a temperature of 130° C. and an electric field strength of 300 V / cm for 40 minutes, and then retaining it at a temperature of 130° C. and an electric field strength of 900 V / cm for 100 minutes; after oil-water separation, obtaining demetallized hydrocarbon oil and a decalcifying agent aqueous solution after reaction; analysis showed that the demetallized hydrocarbon oil had a calcium content of 23.9 μg / g, a magnesium content of 0.41 μg / g, and a sodium content of 1.8 μg / g; and the calcium content of the decalcifying agent aqueous solution after reaction was 0.09 wt% and 0.02 wt% respectively.

[0150] S2. The decalcifying agent aqueous solution obtained after the reaction in S1 was pretreated using a microfiltration purification system (composed of a two-stage microfiltration system with filtration precisions of 6 μm and 2 μm, respectively, with the microfiltration membranes made of ceramic and polycarbonate, respectively) to remove suspended matter, silt, and other impurities. The pretreated filtrate was sequentially sent to a primary nanofiltration system and a secondary nanofiltration system (both the two-stage nanofiltration systems used monovalent ion selective permeable nanofiltration membranes made of aromatic polyamide; the primary nanofiltration system used a tubular nanofiltration membrane, and the secondary nanofiltration system used a roll nanofiltration membrane) for treatment at a pressure of 0.8 MPa. Cross-flow filtration was used to separate divalent calcium and magnesium ions from monovalent sodium ions, obtaining a sodium ion-containing filtrate and a concentrated solution of the reaction product of calcium ions and the decalcifying agent. The retention rates of calcium and magnesium ions were 95.3%, and the retention rate of sodium ions was 4%. The recovery rate of the filtrate was 85%. The obtained sodium ion-containing filtrate was sent to a reverse osmosis system (using a spiral reverse osmosis membrane made of polypiperazineamide) for reverse osmosis treatment. The operating pressure of the reverse osmosis system was 4 MPa to obtain fresh water without metal salts and a first sodium ion-containing concentrate. The sodium salt rejection rate was 97%, and the fresh water recovery rate was 85%.

[0151] S3, in the first solidification reaction tank, the concentrated solution of the reaction product of calcium ions and the decalcifying agent flowing out of the nanofiltration system in S2 is subjected to a first precipitation reaction with sulfuric acid flowing out of the first precipitant storage tank (the amount of sulfuric acid is the theoretical amount of sulfuric acid when the calcium ions in the concentrated solution of the reaction product of calcium ions and the decalcifying agent are completely reacted), the reaction temperature is 35°C, the time is 30min, and a feed liquid containing calcium sulfate precipitate is generated; a filter is used to perform a first solid-liquid separation under the conditions of a temperature of 35°C and a pressure of 0.25MPa to obtain a first recovered concentrated water and a calcium sulfate solid residue, and the first recovered concentrated water is discharged into the second solidification reaction tank; in the second solidification reaction tank, the first recovered concentrated water (sulfur The invention discloses a method for preparing a first recovered concentrated water containing barium sulfate, wherein the first recovered concentrated water contains barium hydroxide, the first recovered concentrated water contains barium sulfate, the second ...

[0152] Under 35 ℃ of conditions, in a calcium salt slag tank, the calcium sulfate solid residue is washed (with the weight of the calcium sulfate solid residue as benchmark, the consumption of water is 100wt%), standing and stratifying, and repeatedly washing until the pH value of the wash water is 7, stopping washing; under 35 ℃ and normal pressure, centrifuge with a rotating speed of 3500r / min, and the isolated calcium residue is dried in a first drying system at 160 ℃ to a moisture content of less than or equal to 1wt%, obtaining a calcium sulfate product (calcium sulfate purity is 95.2wt%, reaching building gypsum quality standard);

[0153] Under normal temperature conditions, the barium sulfate solid slag is washed with water (the amount of water is 200wt% based on the weight of the barium sulfate solid slag) in a barium salt slag tank, allowed to stand for stratification, and the water washing is repeated until the pH value of the washing water reaches 7, and the water washing is stopped; the barium slag is allowed to stand for sedimentation and stratification at normal temperature and pressure, and the separated barium slag is dried in a second drying system at 120° C. until the moisture content is less than or equal to 1wt%, thereby obtaining a barium sulfate product (barium sulfate purity is 97.1wt%, meeting the quality standard of precipitated barium sulfate);

[0154] S4. In the evaporation and condensation unit, the first sodium ion-containing concentrated solution obtained in S2 is evaporated and concentrated at 200° C. and condensed at 40° C. to obtain a second sodium ion-containing concentrated solution and evaporated condensate. The obtained second sodium ion-containing concentrated solution (having a sodium salt content of 18 wt %, meeting the quality standard for brine drilling fluid) is placed in a brine storage tank. The evaporated condensate, the second recovered concentrated water obtained in S3, and the fresh water free of metal salts obtained in S2 are mixed in a hydrocarbon oil decalcifying agent aqueous solution tank. The obtained recovered aqueous solution containing the hydrocarbon oil decalcifying agent (having a sulfate content of 52 mg / L) is returned to S1 for recycling.

[0155] Example 7

[0156] The hydrocarbon oil to be treated in this embodiment is residual oil, and the metal ion contents are as follows: calcium ion 1469 μg / g, magnesium ion 4.3 μg / g, and sodium ion 123.5 μg / g.

[0157] Demetallization of hydrocarbon oil is carried out as follows:

[0158] S1. Mixing a hydrocarbon oil decalcifying agent (formic acid) and water (based on the weight of the residual oil, the contents of the hydrocarbon oil decalcifying agent and water are 1.47 wt% and 11 wt%, respectively) to obtain a decalcifying agent aqueous solution; mixing the decalcifying agent aqueous solution and the residual oil using an emulsifying shear instrument at a temperature of 135° C. and a pressure of 0.6 MPa; then placing the oil-water mixture in an electric desalting tank, retaining it for 30 minutes at a temperature of 135° C. and an electric field strength of 200 V / cm, and then retaining it for 150 minutes at a temperature of 135° C. and an electric field strength of 1100 V / cm; after oil-water separation, obtaining demetallized hydrocarbon oil and a decalcifying agent aqueous solution after reaction; analyzing the demetallized hydrocarbon oil to obtain a calcium content of 72 μg / g, a magnesium content of 1.64 μg / g, and a sodium content of 1.7 μg / g; and the calcium content of the decalcifying agent aqueous solution after reaction was 0.7 wt% and 0.061 wt%;

[0159] S2. The decalcifying agent aqueous solution obtained after the reaction in S1 is pretreated using a microfiltration purification system (composed of a two-stage microfiltration system with filtration precisions of 8 μm and 0.8 μm, respectively, with the microfiltration membranes made of ceramic and polypropylene, respectively) to remove suspended matter, silt, and other impurities. The pretreated filtrate is sequentially sent to a primary nanofiltration system and a secondary nanofiltration system (both the two-stage nanofiltration systems use monovalent ion selective permeable nanofiltration membranes made of aromatic polyamide; the primary nanofiltration system uses a tubular nanofiltration membrane, and the secondary nanofiltration system uses a roll nanofiltration membrane) for treatment at a treatment pressure of 2 MPa. Cross-flow filtration is used to separate divalent calcium and magnesium ions from monovalent sodium ions, obtaining a sodium ion-containing filtrate and a concentrated solution of the reaction product of calcium ions and the decalcifying agent. The retention rates of calcium and magnesium ions are 96%, and the retention rate of sodium ions is 10%. The recovery rate of the filtrate is 75%. The obtained sodium ion-containing filtrate was sent to a reverse osmosis system (using a spiral reverse osmosis membrane made of polypiperazineamide) for reverse osmosis treatment. The operating pressure of the reverse osmosis system was 5 MPa to obtain fresh water without metal salts and a first sodium ion-containing concentrate. The sodium salt rejection rate was 98%, and the fresh water recovery rate was 75%.

[0160] S3, in the first solidification reaction tank, the concentrated solution of the reaction product of calcium ions and the decalcifying agent flowing out of the nanofiltration system in S2 is subjected to a first precipitation reaction with sulfuric acid flowing out of the first precipitant storage tank (the amount of sulfuric acid is the theoretical amount of sulfuric acid when the calcium ions in the concentrated solution of the reaction product of calcium ions and the decalcifying agent are completely reacted), the reaction temperature is 40°C, the time is 30min, and a feed liquid containing calcium sulfate precipitate is generated; a cyclone separator is used to perform a first solid-liquid separation under the conditions of a temperature of 40°C and a pressure of 0.35MPa to obtain a first recovered concentrated water and a calcium sulfate solid residue, and the first recovered concentrated water is discharged to the second solidification reaction tank; in the second solidification reaction tank, the first recovered concentrated water is discharged to the second solidification reaction tank; Water (sulfate content of 1580 mg / L) is subjected to a second precipitation reaction with barium chloride flowing out of a second precipitant storage tank (the amount of barium chloride used is the theoretical amount of barium chloride required for complete reaction with sulfate contained in the first recovered concentrated water), the reaction temperature is 40° C., and the reaction time is 5 minutes to generate a feed liquid containing barium sulfate precipitate; a second solid-liquid separation is performed using a centrifuge at a speed of 3000 r / min to obtain a second recovered concentrated water and a barium sulfate solid residue, and the second recovered concentrated water is discharged into a hydrocarbon oil decalcifying agent aqueous solution tank; wherein the obtained calcium sulfate solid residue and barium sulfate solid residue are respectively washed, separated, and dried to obtain a calcium sulfate product and a barium sulfate product, respectively, which specifically comprises the following steps:

[0161] Under 40 ℃ of conditions, in a calcium salt slag tank, the calcium sulfate solid residue is washed (with the weight of the calcium sulfate solid residue as benchmark, the consumption of water is 100wt%), standing and stratifying, and repeatedly washing until the pH value of the wash water is 7, stops washing; At a temperature of 40 ℃, a pressure is filtered with a hydrocyclone under the condition of 0.35 MPa, and the isolated calcium residue is dried to a moisture content of less than or equal to 1wt% in a first drying system at 160 ℃ to obtain a calcium sulfate product (calcium sulfate purity is 96.2wt%, reaching a building gypsum quality standard);

[0162] The barium sulfate solid residue was washed with water in a barium salt slag tank at 40° C. (the amount of water was 150 wt % based on the weight of the barium sulfate solid residue), allowed to stand for stratification, and repeatedly washed with water until the pH value of the washing water reached 6.5; the barium slag was allowed to stand for sedimentation and stratification at 40° C. and normal pressure, and the separated barium slag was dried in a second drying system at 135° C. until the moisture content was less than or equal to 1 wt %, thereby obtaining a barium sulfate product (barium sulfate purity was 95.7 wt %, meeting the quality standard of precipitated barium sulfate);

[0163] S4. In the evaporation and condensation unit, the first sodium ion-containing concentrated solution obtained in S2 is evaporated and concentrated at 150° C. and condensed at 20° C. to obtain a second sodium ion-containing concentrated solution and evaporated condensate. The obtained second sodium ion-containing concentrated solution (having a sodium salt content of 17 wt %, meeting the quality standard for brine drilling fluid) is placed in a brine storage tank. The evaporated condensate, the second recovered concentrated water obtained in S3, and the fresh water free of metal salts obtained in S2 are mixed in a hydrocarbon oil decalcifying agent aqueous solution tank. The obtained recovered aqueous solution containing the hydrocarbon oil decalcifying agent (having a sulfate content of 45 mg / L) is returned to S1 for recycling.

[0164] Example 8

[0165] The hydrocarbon oil to be treated in this embodiment is extra-heavy oil, and the metal ion contents are as follows: calcium ion 1980 μg / g, magnesium ion 23.7 μg / g, and sodium ion 98.1 μg / g.

[0166] Demetallization of hydrocarbon oil is carried out as follows:

[0167] S1, hydrocarbon oil decalcifying agent (formic acid) and water are mixed (with the weight of super heavy oil as a benchmark, the contents of hydrocarbon oil decalcifying agent and water are 1.8wt% and 20wt% respectively) to obtain a decalcifying agent aqueous solution; at a temperature of 120 ℃, a pressure of 1MPa, the decalcifying agent aqueous solution is mixed with a membrane reactor with a metal membrane having a pore size of 50μm for super heavy oil; the oil-water mixture is then placed in an electric desalting tank, and is left for 6min at a temperature of 120 ℃ and an electric field strength of 250V / cm, and then is left for 60min at a temperature of 120 ℃ and an electric field strength of 750V / cm; after oil-water separation, demetallized hydrocarbon oil and a reacted decalcifying agent aqueous solution are obtained; analysis shows that the demetallized hydrocarbon oil has a calcium content of 37.8μg / g, a magnesium content of 4.3μg / g, and a sodium content of 1.3μg / g; the reacted decalcifying agent aqueous solution has a calcium content of 0.97wt% and a sodium content of 0.048wt%;

[0168] S2. The decalcifying agent aqueous solution obtained after the reaction in S1 is pretreated using a microfiltration purification system (composed of a two-stage microfiltration system with filtration precisions of 5 μm and 0.2 μm, respectively, with the microfiltration membranes made of polycarbonate and polyvinyl chloride, respectively) to remove suspended matter, silt, and other impurities. The pretreated filtrate is sequentially sent to a primary nanofiltration system and a secondary nanofiltration system (both the two-stage nanofiltration systems use monovalent ion selective permeable nanofiltration membranes made of aromatic polyamide; the primary nanofiltration system uses a tubular nanofiltration membrane, and the secondary nanofiltration system uses a roll nanofiltration membrane) for treatment at a treatment pressure of 2 MPa. Cross-flow filtration is used to separate divalent calcium and magnesium ions from monovalent sodium ions, obtaining a sodium ion-containing filtrate and a concentrated solution of the reaction product of calcium ions and the decalcifying agent. The retention rates of calcium and magnesium ions are 98%, and the retention rate of sodium ions is 5%. The recovery rate of the filtrate is 75%. The obtained sodium ion-containing filtrate was sent to a reverse osmosis system (using a spiral reverse osmosis membrane made of polypiperazineamide) for reverse osmosis treatment. The operating pressure of the reverse osmosis system was 6 MPa to obtain fresh water without metal salts and a first sodium ion-containing concentrate. The sodium salt rejection rate was 98%, and the fresh water recovery rate was 85%.

[0169] S3, in the first solidification reaction tank, the concentrated solution of the reaction product of calcium ions and the decalcifying agent discharged from the nanofiltration system in S2 is subjected to a first precipitation reaction with phosphoric acid discharged from the first precipitant storage tank (the amount of phosphoric acid used is the theoretical amount of phosphoric acid when the calcium ions in the concentrated solution of the reaction product of calcium ions and the decalcifying agent are completely reacted), the reaction temperature is 50°C, the time is 10min, and a feed liquid containing calcium phosphate precipitate is generated; suction filtration is performed under a pressure of 0.35MPa to obtain a first recovered concentrated water and calcium phosphate solid residue, and the first recovered concentrated water is discharged to the second solidification reaction tank; in the second solidification reaction tank, the first recovered concentrated water (phosphate content of 5 80 mg / L) is subjected to a second precipitation reaction with barium chloride flowing out of a second precipitant storage tank (the amount of barium chloride used is the theoretical amount of barium chloride required for complete reaction with phosphate radicals contained in the first recovered concentrated water), the reaction temperature is 20° C., and the time is 20 min to generate a feed liquid containing barium phosphate precipitate; a second solid-liquid separation is performed using a centrifuge at a speed of 3000 r / min to obtain a second recovered concentrated water and a barium phosphate solid residue, and the second recovered concentrated water is discharged into a hydrocarbon oil decalcifying agent aqueous solution tank; wherein the obtained calcium phosphate solid residue and barium phosphate solid residue are respectively washed, separated and dried to obtain a calcium phosphate product and a barium phosphate product, respectively, which specifically comprises the following steps:

[0170] The calcium phosphate solid residue is washed with water in a calcium salt slag tank at room temperature (with the weight of the calcium phosphate solid residue as the benchmark and the amount of water being 120 wt %), allowed to stand for stratification, and repeatedly washed with water until the pH value of the wash water reaches 7; the washing is stopped; suction filtration is performed under a pressure of −0.1 MPa, and the separated calcium residue is dried in a first drying system at 190° C. to a moisture content of less than or equal to 1 wt %, thereby obtaining a calcium phosphate product (calcium phosphate purity being 93.7 wt %, meeting the quality standard for building materials);

[0171] Under normal temperature conditions, the barium phosphate solid slag is washed with water in a barium salt slag tank (the amount of water is 100wt% based on the weight of the barium phosphate solid slag), allowed to stand for stratification, and repeatedly washed with water until the pH value of the washing water reaches 6; the water is allowed to stand for sedimentation and stratification under normal temperature and pressure conditions, and the separated barium slag is dried in a second drying system at 120° C. until the moisture content is less than or equal to 1wt%, thereby obtaining a barium phosphate product (the purity of the barium phosphate is 95.7wt%, meeting the quality standard of precipitated barium phosphate);

[0172] S4. In the evaporation and condensation unit, the first sodium ion-containing concentrated solution obtained in S2 is evaporated and concentrated at 120° C. and condensed at 35° C. to obtain a second sodium ion-containing concentrated solution and evaporated condensate. The obtained second sodium ion-containing concentrated solution (having a sodium salt content of 13 wt %, meeting the quality standard for brine drilling fluid) is placed in a brine storage tank. The evaporated condensate, the second recovered concentrated water obtained in S3, and the metal salt-free fresh water obtained in S2 are mixed in a hydrocarbon oil decalcifying agent aqueous solution tank. The obtained recovered aqueous solution containing the hydrocarbon oil decalcifying agent (with a phosphate content of 39 mg / L) is returned to S1 for recycling.

[0173] Example 9

[0174] The hydrocarbon oil to be treated in this embodiment is extra-heavy oil, and the metal ion contents are as follows: calcium ion 2250 μg / g, magnesium ion 20.3 μg / g, and sodium ion 94.1 μg / g.

[0175] Demetallization of hydrocarbon oil is carried out as follows:

[0176] S1, hydrocarbon oil decalcifying agent (formic acid) and water are mixed (with the weight of super heavy oil as a benchmark, the contents of hydrocarbon oil decalcifying agent and water are 5wt% and 6wt% respectively) to obtain a decalcifying agent aqueous solution; at a temperature of 135 ℃ and a pressure of 1.5 MPa, the decalcifying agent aqueous solution is mixed with a membrane reactor having a metal membrane with a pore size of 20 μm for super heavy oil; the oil-water mixture is then placed in an electric desalting tank, and is left for 6 min at a temperature of 135 ℃ and an electric field strength of 250 V / cm, and then is left for 60 min at a temperature of 135 ℃ and an electric field strength of 750 V / cm; after oil-water separation, demetallized hydrocarbon oil and a reacted decalcifying agent aqueous solution are obtained; analysis shows that the demetallized hydrocarbon oil has a calcium content of 32.8 μg / g, a magnesium content of 4 μg / g, and a sodium content of 1.9 μg / g; the reacted decalcifying agent aqueous solution has a calcium content of 1.11 wt% and a sodium content of 0.046 wt%;

[0177] S2. The decalcifying agent aqueous solution obtained in S1 was pretreated using a microfiltration purification system (composed of a two-stage microfiltration system with filtration precisions of 8 μm and 0.5 μm, respectively, with the microfiltration membranes made of ceramic and polyvinyl chloride, respectively) to remove suspended matter, silt, and other impurities. The pretreated filtrate was sequentially sent to a primary nanofiltration system and a secondary nanofiltration system (both nanofiltration systems used monovalent ion selective permeable nanofiltration membranes made of aromatic polyamide; the primary nanofiltration system used a tubular nanofiltration membrane, and the secondary nanofiltration system used a roll nanofiltration membrane) for treatment at a treatment pressure of 2 MPa. Cross-flow filtration was used to separate divalent calcium and magnesium ions from monovalent sodium ions, obtaining a sodium ion-containing filtrate and a concentrated solution of the reaction product of calcium ions and the decalcifying agent. The retention rates of calcium and magnesium ions were 95.3%, and the retention rate of sodium ions was 5%. The recovery rate of the filtrate was 75%. The obtained sodium ion-containing filtrate was sent to a reverse osmosis system (using a spiral reverse osmosis membrane made of polypiperazineamide) for reverse osmosis treatment. The operating pressure of the reverse osmosis system was 6 MPa to obtain fresh water without metal salts and a first sodium ion-containing concentrate. The sodium salt rejection rate was 90.5%, and the fresh water recovery rate was 75%.

[0178] S3, in the first solidification reaction tank, the concentrated solution of the reaction product of calcium ions and the decalcifying agent flowing out of the nanofiltration system in S2 is subjected to a first precipitation reaction with the phosphoric acid flowing out of the first precipitant storage tank (the amount of phosphoric acid used is the theoretical amount of phosphoric acid when the calcium ions in the concentrated solution of the reaction product of calcium ions and the decalcifying agent are completely reacted), the reaction temperature is 50°C, the time is 25min, and a feed liquid containing calcium phosphate precipitate is generated; suction filtration is performed under a pressure of -0.1MPa to obtain a first recovered concentrated water and a calcium phosphate solid residue, and the first recovered concentrated water is discharged to the second solidification reaction tank; in the second solidification reaction tank, the first recovered concentrated water (phosphate content of 5 80 mg / L) is subjected to a second precipitation reaction with barium chloride flowing out of a second precipitant storage tank (the amount of barium chloride used is the theoretical amount of barium chloride required for complete reaction with phosphate radicals contained in the first recovered concentrated water), the reaction temperature is 20° C., and the time is 15 min to generate a feed liquid containing barium phosphate precipitate; a second solid-liquid separation is performed using a centrifuge at a speed of 2500 r / min to obtain a second recovered concentrated water and a barium phosphate solid residue, and the second recovered concentrated water is discharged into a hydrocarbon oil decalcifying agent aqueous solution tank; wherein the obtained calcium phosphate solid residue and barium phosphate solid residue are respectively washed, separated and dried to obtain a calcium phosphate product and a barium phosphate product, respectively, which specifically comprises the following steps:

[0179] The calcium phosphate solid residue was washed with water in a calcium salt slag tank at 40° C. (with water consumption of 120 wt % based on the weight of the calcium phosphate solid residue), allowed to stand for stratification, and repeatedly washed until the pH value of the wash water reached 7; the washing was stopped; and suction filtration was performed under a pressure of −0.1 MPa. The separated calcium residue was dried in a first drying system at 190° C. to a moisture content of less than or equal to 1 wt %, thereby obtaining a calcium phosphate product (calcium phosphate purity of 95.1 wt %, meeting the quality standard for building materials);

[0180] The barium phosphate solid slag is washed with water in a barium salt slag tank at 40° C. (the amount of water is 70 wt % based on the weight of the barium phosphate solid slag), allowed to stand for stratification, and repeatedly washed with water until the pH value of the washing water reaches 6; the barium phosphate product is dried in a second drying system at 120° C. to a moisture content of less than or equal to 1 wt % to obtain the barium phosphate product (the purity of the barium phosphate is 92.5 wt %, meeting the quality standard of precipitated barium phosphate);

[0181] S4. In the evaporation and condensation unit, the first sodium ion-containing concentrated solution obtained in S2 is evaporated and concentrated at 120° C. and condensed at 50° C. to obtain a second sodium ion-containing concentrated solution and evaporated condensate. The obtained second sodium ion-containing concentrated solution (having a sodium salt content of 13 wt %, meeting the quality standard for brine drilling fluid) is placed in a brine storage tank; the evaporated condensate, the second recovered concentrated water obtained in S3, and the fresh water free of metal salts obtained in S2 are mixed in a hydrocarbon oil decalcifying agent aqueous solution tank, and the obtained recovered aqueous solution containing the hydrocarbon oil decalcifying agent (with a phosphate content of 39 mg / L) is returned to S1 for recycling.

[0182] Example 10

[0183] The hydrocarbon oil was treated for metal ion removal according to the method of Example 8, except that the primary nanofiltration system used a tubular nanofiltration membrane made of cellulose acetate. Specifically, in S2, the pretreated filtrate was sequentially fed into the primary and secondary nanofiltration systems for treatment. The retention rates for calcium and magnesium ions were 90.1%, and the retention rate for sodium ions was 2%. The filtrate recovery rate was 78%. The resulting sodium ion-containing filtrate was fed into a reverse osmosis system for reverse osmosis treatment. The retention rate for sodium salts was 97.5%, and the fresh water recovery rate was 82%.

[0184] Example 11

[0185] The hydrocarbon oil was treated for metal ion removal according to the method of Example 8, except that the primary nanofiltration system used a spiral nanofiltration membrane made of aromatic polyamide. Specifically, in S2, the pretreated filtrate was sequentially fed into the primary and secondary nanofiltration systems for treatment. The retention rates for calcium and magnesium ions were 87%, and the retention rate for sodium ions was 1%. The filtrate recovery rate was 80%. The resulting sodium ion-containing filtrate was fed into a reverse osmosis system for reverse osmosis treatment. The retention rate for sodium salts was 98%, and the fresh water recovery rate was 75%.

[0186] Example 12

[0187] The hydrocarbon oil was treated for metal ion removal according to the method of Example 8, except that the secondary nanofiltration system used a wound nanofiltration membrane made of cellulose acetate. Specifically, in S2, the pretreated filtrate was sequentially fed into the primary and secondary nanofiltration systems for treatment. The retention rates for calcium and magnesium ions were 89%, and the retention rate for sodium ions was 1%. The filtrate recovery rate was 78%. The resulting sodium ion-containing filtrate was fed into a reverse osmosis system for reverse osmosis treatment. The retention rate for sodium salts was 97%, and the fresh water recovery rate was 80%.

[0188] Example 13

[0189] The hydrocarbon oil was treated for metal ion removal according to the method of Example 8, except that the secondary nanofiltration system used a tubular nanofiltration membrane made of aromatic polyamide. Specifically, in S2, the pretreated filtrate was sequentially fed into the primary and secondary nanofiltration systems for treatment. The retention rates for calcium and magnesium ions were 80%, while the retention rate for sodium ions was 0%. The filtrate recovery rate was 85%. The resulting sodium ion-containing filtrate was fed into a reverse osmosis system for reverse osmosis treatment. The retention rate for sodium salts was 97%, and the fresh water recovery rate was 68%.

[0190] Example 14

[0191] The hydrocarbon oil was treated for metal ion removal according to the method of Example 8, except that a spiral wound reverse osmosis membrane made of sulfonated polysulfone was used for the reverse osmosis treatment. Specifically, in S2, the resulting sodium ion-containing filtrate was fed to a reverse osmosis system for reverse osmosis treatment. The sodium salt rejection rate was 94.5%, and the fresh water recovery rate was 70%.

[0192] Example 15

[0193] The hydrocarbon oil was treated for metal ion removal according to the method of Example 8, except that a tubular reverse osmosis membrane made of polypiperazineamide was used for the reverse osmosis treatment. Specifically, in S2, the resulting sodium ion-containing filtrate was fed into a reverse osmosis system for reverse osmosis treatment, resulting in a sodium salt rejection rate of 95% and a fresh water recovery rate of 75%.

[0194] Comparative Example 1

[0195] The hydrocarbon oil was subjected to metal ion removal treatment according to the method of Example 1, except that steps S2, S3, and S4 were not performed. The decalcifying agent aqueous solution obtained after the reaction in S1 was not subjected to membrane separation in S2. Since the reaction product of the calcium ions and the decalcifying agent was not concentrated, the calcium concentration in the decalcifying agent aqueous solution after the reaction was too low to carry out the precipitation reaction and the steps after S2. The decalcifying agent produced after the hydrocarbon oil was demetallated could not be recycled and had to be discharged, polluting the environment and causing waste.

[0196] Comparative Example 2

[0197] The hydrocarbon oil was subjected to metal ion removal treatment according to the method of Example 8, except that step S2 was not performed. The decalcifying agent aqueous solution obtained after the reaction in S1 was not subjected to membrane separation in S2. Since the reaction product of calcium ions and the decalcifying agent was not concentrated, the calcium concentration in the decalcifying agent aqueous solution after the reaction was low. The scale of the device for the solidification reaction in S3 was four times that of Example 8. Moreover, the sodium ion content in the hydrocarbon oil after the metal ion removal treatment reached 5.5 μg / g after the 20th cycle, and the sodium ion content in the hydrocarbon oil after the metal ion removal treatment reached 11.3 μg / g after the 40th cycle. The sodium ion content in the hydrocarbon oil after the metal ion removal treatment exceeded the processing requirement of a salt content of no more than 5 μg / g after the hydrocarbon oil pretreatment. The decalcifying agent aqueous solution after the reaction could only be discharged for treatment, which failed to effectively realize the recycling of the hydrocarbon oil decalcifying agent and the resource utilization of the hydrocarbon oil decalcification wastewater.

[0198] Test Case

[0199] The recovered aqueous solution containing hydrocarbon oil decalcifying agent obtained in each example was recycled for hydrocarbon oil metal ion removal treatment. The metal ion content in the hydrocarbon oil after metal ion removal treatment, the decalcifying agent content in the recovered aqueous solution containing hydrocarbon oil decalcifying agent, and the water replenishment conditions are shown in Table 1.

[0200] Table 1

[0201] Note: “ / ” indicates that the corresponding index does not need to be analyzed, and the 0th time indicates that the hydrocarbon oil is treated with the initially prepared decalcifying agent aqueous solution.

[0202] Examples 1-9 were used to perform metal ion removal treatment on hydrocarbon oils having different metal ion contents. The results in Table 1 show that, for hydrocarbon oils having different metal ion contents, the method of the present invention was used to perform metal ion removal treatment on hydrocarbon oils. After the recovered aqueous solution containing the decalcifying agent was recycled for 40 times, the removal effect of metal ions in the hydrocarbon oil was still comparable to that of the 0th cycle (i.e., a fresh hydrocarbon decalcifying agent aqueous solution), indicating that the recycling of the hydrocarbon oil decalcifying agent and the resource utilization of decalcification wastewater can be well achieved. However, the decalcification agent aqueous solution obtained after the reaction in Comparative Example 2 was not subjected to membrane separation. Not only did the scale of the equipment required for the solidification reaction increase significantly, but the sodium ion content in the hydrocarbon oil after the metal ion desorption treatment increased significantly with the increase in the number of cycles. When the number of cycles increased to 20, the sodium ion content in the hydrocarbon oil after the metal ion desorption treatment was 5.5 μg / g, and the sodium chloride content in the hydrocarbon oil was unqualified (the sodium chloride content in the hydrocarbon oil is generally required to be less than 5 mg Nacl / L after electro-desalting. If it is greater than 5 mg Nacl / L, the crude oil electro-desalting is judged to be unqualified). The hydrocarbon oil decalcification wastewater can only be discharged, and the recycling and resource utilization of the hydrocarbon oil decalcification agent cannot be effectively achieved.

[0203] In addition, Examples 10-13 respectively change the material and form of the nanofiltration membrane in the primary nanofiltration system and the secondary nanofiltration system. Compared with Example 8, the calcium and magnesium ion rejection rate of the nanofiltration system in Examples 10-13 is reduced, the recovery rate of the nanofiltration filtrate is increased, the fresh water recovery rate of the reverse osmosis system is reduced, and the amount of water replenishment during the circulation process is increased, indicating that the calcium and magnesium ion rejection rate of the nanofiltration system is reduced, more calcium and magnesium ions enter the reverse osmosis system, increasing the processing load of the reverse osmosis membrane, and these calcium and magnesium ions eventually enter the S4 stage. There is a risk of equipment scaling in the S4 stage, which reduces the evaporation rate and increases the processing difficulty. Examples 14 and 15 respectively change the material and form of the reverse osmosis membrane in the reverse osmosis system. Compared with Example 8, the fresh water recovery rate of the reverse osmosis system in Examples 14 and 15 is reduced, indicating that changing the material and form of the reverse osmosis membrane in the reverse osmosis system increases the amount of reverse osmosis concentrated water and increases the processing load of the S4 stage.

[0204] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for removing metal ions from hydrocarbon oil, characterized in that: The method comprises the following steps: S1, subjecting the hydrocarbon oil and the decalcifying agent aqueous solution to an electrical desalting treatment to obtain a demetallized hydrocarbon oil and a reacted decalcifying agent aqueous solution; S2, subjecting the decalcifying agent aqueous solution after the reaction to membrane separation to obtain a concentrated solution of the reaction product of calcium ions and the decalcifying agent, a first concentrated solution containing sodium ions, and fresh water; S3, decalcifying the concentrated solution of the reaction product of the calcium ions and the decalcifying agent to obtain a decalcified concentrated solution of the decalcifying agent; S4, evaporating and condensing the first sodium ion-containing concentrated solution to obtain a second sodium ion-containing concentrated solution and condensed water; mixing the decalcified decalcifying agent concentrated solution, the fresh water and the condensed water and returning the mixture to S1.

2. The method according to claim 1, characterized in that: In S3, the decalcification method includes: mixing the concentrated solution of the reaction product of the calcium ions and the decalcifying agent with a first precipitant to perform a first precipitation reaction, and then performing a first solid-liquid separation; mixing the obtained liquid phase product with a second precipitant to perform a second precipitation reaction, and performing a second solid-liquid separation to obtain the decalcified decalcifying agent concentrated solution; Preferably, the first precipitant is sulfuric acid or phosphoric acid; Preferably, the temperature of the first precipitation reaction is 20-50°C and the time is 5-30min; Preferably, the second precipitant is barium chloride, barium hydroxide or barium acetate; Preferably, the temperature of the second precipitation reaction is 20-50°C and the time is 5-30 minutes.

3. The method according to claim 1 or 2, characterized in that: In S1, based on the weight of the hydrocarbon oil, the contents of the decalcifying agent and water in the decalcifying agent aqueous solution are 0.01-5wt% and 1-25wt%, respectively; Preferably, the decalcifying agent is selected from at least one of formic acid, acetic acid, propionic acid and butyric acid; Preferably, the process of the electrical desalination treatment comprises: mixing the hydrocarbon oil and the decalcifying agent aqueous solution at a temperature of 50-150°C and a pressure of 0.02-1MPa, then leaving the mixture at an electric field strength of 50-500V / cm for 1-60min, and then leaving the mixture at an electric field strength of 500-1500V / cm for 5-200min.

4. The method according to any one of claims 1 to 3, characterized in that: In S2, the membrane separation process comprises: subjecting the decalcifying agent aqueous solution after the reaction to at least one stage of nanofiltration treatment, preferably two stages, to obtain a concentrated solution and a filtrate of the reaction product of the calcium ions and the decalcifying agent, and then subjecting the filtrate to at least one stage of reverse osmosis treatment, preferably one stage, through a reverse osmosis membrane to obtain the first sodium ion-containing concentrated solution and the fresh water; Preferably, the pressure of the nanofiltration treatment is 0.2-2 MPa; Preferably, the nanofiltration membrane is selected from a monovalent ion selective permeable nanofiltration membrane; Preferably, the material of the nanofiltration membrane is selected from at least one of aromatic polyamide, polypiperazineamide, cellulose acetate and sulfonated polyethersulfone, preferably aromatic polyamide; Preferably, the pressure of the reverse osmosis treatment is 2-6 MPa; Preferably, the material of the reverse osmosis membrane is selected from at least one of aromatic polyamide, polypiperazineamide, polyimide and sulfonated polysulfone, preferably polypiperazineamide.

5. The method according to claim 4, characterized in that The membrane separation process further comprises: pre-treating the decalcification agent aqueous solution after the reaction, and then performing the nanofiltration treatment; Preferably, the pretreatment method comprises: subjecting the reacted decalcifying agent aqueous solution to microfiltration through a microfiltration membrane; Preferably, the material of the microfiltration membrane is selected from at least one of ceramic, polypropylene, polycarbonate, polyvinyl chloride, polysulfone, polyvinylidene fluoride and polytetrafluoroethylene.

6. The method according to any one of claims 1 to 5, characterized in that: In S4, the evaporation temperature is 120-200°C, and the condensation temperature is 20-50°C; Preferably, the content of sodium salt in the second sodium ion-containing concentrated solution is 10-30 wt%.

7. The method according to any one of claims 2 to 6, characterized in that: The method further comprises: washing, separating slag and drying the solid phase product obtained by the first precipitation reaction to obtain a calcium salt product; Preferably, the method further comprises: washing, slagging and drying the solid phase product obtained by the second precipitation reaction to obtain a barium salt product.

8. A device for removing metal ions from hydrocarbon oil, characterized in that: The device comprises: An electrical desalting unit, used for conducting electrical desalting treatment on hydrocarbon oil and decalcifying agent aqueous solution to remove metal ions in the hydrocarbon oil; A membrane separation unit, used for performing membrane separation on the water phase flowing out of the electrical desalination unit; an evaporation and condensation unit, used for evaporating and concentrating the sodium ion-containing concentrated liquid flowing out of the membrane separation unit, and condensing the obtained gas phase product into condensed water; The decalcification treatment unit is used to decalcify the concentrated solution of the reaction product of calcium ions and decalcification agent flowing out of the membrane separation unit, and mix the obtained liquid phase product, the fresh water flowing out of the membrane separation unit and the condensed water flowing out of the evaporation and condensation unit and return them to the electrical desalination unit.

9. The device according to claim 8, characterized in that The electric desalination unit comprises a mixer and an electric desalination tank which are connected to each other; Preferably, the membrane separation unit comprises: a nanofiltration system for subjecting the aqueous phase flowing out of the electrical desalination unit to nanofiltration treatment; a reverse osmosis system for subjecting the filtrate flowing out of the nanofiltration system to reverse osmosis treatment; Preferably, the membrane separation unit further comprises a microfiltration purification system for removing suspended matter and sediment from the water phase flowing out of the electrical desalination unit and feeding the water phase into the nanofiltration system; Preferably, the evaporation-condensation unit comprises an evaporator and a condenser connected to each other.

10. The device according to claim 9, characterized in that The decalcification processing unit comprises: A first solidification reaction tank is used to mix the concentrated solution of the reaction product of the calcium ions and the decalcifying agent flowing out of the nanofiltration system with a first precipitant to perform a first precipitation reaction; A first solid-liquid separator, used for performing a first solid-liquid separation on the liquid flowing out of the first solidification reaction tank; A second solidification reaction tank is used to mix the liquid product flowing out of the first solid-liquid separator with a second precipitant to perform a second precipitation reaction; The second solid-liquid separator is used to perform a second solid-liquid separation on the material flowing out of the second solidification reaction tank, and the obtained liquid phase product, the condensed water flowing out of the condenser and the fresh water flowing out of the reverse osmosis system are mixed through a hydrocarbon oil decalcifying agent aqueous solution tank and then flow into the mixer.

11. The device according to claim 10, characterized in that The decalcification treatment unit also includes: a first drying system for drying the solid phase product flowing out of the first solid-liquid separator to obtain a calcium salt product; and a second drying system for drying the solid phase product flowing out of the second solid-liquid separator to obtain a barium salt product.

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