Top circulation reflux salt leaching system

Abstract

The utility model relates to the technical field of petrochemical engineering, in particular to a top cycle reflux salt leaching system which comprises a coking fractionating tower, a top cycle oil outlet of the coking fractionating tower and an outlet of a water injection pump are respectively communicated with a feed port of a mixer, and a discharge port of the mixer is communicated with an inlet of a primary oil-water separator. A water outlet of the first-stage oil-water separator is communicated with an inlet of the gas-liquid separator, and a liquid outlet of the gas-liquid separator is communicated with an inlet of the second-stage oil-water separator; an oil outlet of the first-stage oil-water separator and an oil outlet of the second-stage oil-water separator are both communicated with a reflux inlet of the coking fractionating tower; and a water outlet of the secondary oil-water separator is communicated with an inlet of the water injection pump. According to the utility model, the first-stage oil-water separator, the gas-liquid separator and the second-stage oil-water separator are sequentially arranged for desalting and degassing the top cycle oil, and water separated by the second-stage oil-water separator is used for washing the top cycle oil in the coking fractionating tower, so that the top of the coking fractionating tower is prevented from being blocked, and meanwhile, the desalting water consumption is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of petrochemical industry, in particular to a top circulation reflux salt washing system. Background Art

[0002] Coking is a deep thermal cracking process that converts heavy oil into dry gas, liquefied petroleum gas, coker gasoline, coker diesel, coker gas oil, and coke. Coking processes primarily include delayed coking, kettle coking, open-hearth coking, fluidized coking, and flexicoking. Delayed coking uses heavy oil as a raw material, producing pyrolysis gas, pyrolysis oil, and coke through high-temperature cracking. Utilizing high-temperature pyrolysis technology, the delayed coking process boasts a fully reacted, low impurity content, high production efficiency, and resource utilization, making it widely used in the petrochemical, metallurgical, and power industries.

[0003] The coking fractionator is one of the main equipment in the delayed coking process, which is used to decompose the crude oil into fractions with different boiling point ranges. The raw oil used in the delayed coking process is mostly residual oil, inferior heavy oil, dirty oil and slurry from atmospheric and vacuum distillation units, and there is a possibility of mixing with oil recovery additives. These raw oils usually contain high levels of nitrogen compounds, sulfides and chlorides. Nitrides and chlorides are easy to form ammonium chloride crystal particles at the top of the coking distillation tower. When the temperature at the top of the coking distillation tower is low, the ammonium chloride crystal particles will dissolve in the condensate at the top of the coking distillation tower, and condense-vaporize cycle between several layers of tower plates at the top of the coking distillation tower with the condensate, forming a viscous semi-fluid. This semi-fluid is mixed with rust, coke powder, etc. and deposited on the tower plates, tower top reflux lines, downcomers and liquid receiving trays. When it accumulates to a certain extent, it will hinder the flow of liquid and block the tower plates, resulting in increased pressure drop in the coking distillation tower, reduced gas-liquid contact, and reduced distillation efficiency. In severe cases, accidents such as tower flushing may occur, which will endanger the safe operation of the rich gas compressor. Utility Model Content

[0004] In response to the technical problem that the top of the coking distillation tower is prone to clogging in the existing technology, the utility model provides a top circulation reflux salt washing system, which is equipped with a first-level oil-water separator, a gas-liquid separator and a second-level oil-water separator in sequence to desalt and degas the top circulating oil, and uses the water separated by the second-level oil-water separator to wash the top circulating oil in the coking distillation tower, thereby preventing the top of the coking distillation tower from being clogging and reducing the water consumption for desalting.

[0005] The technical solution of this utility model is as follows:

[0006] A top circulation reflux salt washing system includes a coking fractionating tower, wherein the top circulation oil outlet and the outlet of the water injection pump of the coking fractionating tower are respectively connected to the feed inlet of a mixer, the discharge outlet of the mixer is connected to the inlet of a primary oil-water separator, the drain outlet of the primary oil-water separator is connected to the inlet of a gas-liquid separator, and the drain outlet of the gas-liquid separator is connected to the inlet of a secondary oil-water separator;

[0007] The oil discharge port of the first-stage oil-water separator and the oil discharge port of the second-stage oil-water separator are both connected to the reflux port of the coking fractionation tower. The top circulating oil discharged from the oil discharge port of the first-stage oil-water separator and the oil discharge port of the second-stage oil-water separator enters the top of the coking fractionation tower and re-participates in the top circulation of the coking fractionation tower; the drain port of the second-stage oil-water separator is connected to the inlet of the water injection pump;

[0008] The first-stage oil-water separator is equipped with a safety valve, which is connected to the gas-liquid separator. The safety valve maintains the pressure inside the first-stage oil-water separator by releasing gas into the gas-liquid separator. The gas-liquid separator inlet is also connected to the top of the coking fractionation tower.

[0009] Furthermore, the top circulating oil outlet and reflux port of the coking fractionation tower are both arranged at the top of the coking fractionation tower. The top circulating oil outlet is connected to the feed port of the mixer via a pipeline, and a flow monitoring device is arranged on the pipeline.

[0010] Furthermore, the injection pump inlet is connected to coking tank recycled water, which is purified water treated in the coking wastewater sedimentation tank. A pressure monitoring device is installed at the injection pump inlet. The injection pump inlet can also be connected to desalinated water with a lower salt content as needed.

[0011] Furthermore, the exhaust port of the gas-liquid separator is connected to the hydrogen production device. The gas phase discharged from the exhaust port of the gas-liquid separator is processed by the absorption stabilization unit and then enters the hydrogen production device to participate in hydrogen production.

[0012] Furthermore, the discharge port of the gas-liquid separator is also connected to the inlet of the water injection pump. A valve is provided between the discharge port of the gas-liquid separator and the inlet of the secondary oil-water separator and the inlet of the water injection pump. By adjusting the valve, the discharge port of the gas-liquid separator can be connected to either the inlet of the secondary oil-water separator or the inlet of the water injection pump, or simultaneously to the inlet of the secondary oil-water separator and the inlet of the water injection pump. When the discharge port of the gas-liquid separator is only connected to the inlet of the water injection pump, the liquid discharged from the gas-liquid separator enters the mixer to desalinate the top circulating oil; when the discharge port of the gas-liquid separator is only connected to the inlet of the secondary oil-water separator, the liquid discharged from the gas-liquid separator enters the secondary oil-water separator for secondary oil-water separation; when the discharge port of the gas-liquid separator is respectively connected to the inlet of the water injection pump and the inlet of the secondary oil-water separator, a part of the liquid discharged from the gas-liquid separator enters the mixer to desalinate the top circulating oil, and the other part of the liquid enters the secondary oil-water separator for secondary oil-water separation.

[0013] Furthermore, the drain outlet of the secondary oil-water separator is also connected to the inlet of the pretreatment device of the sulfur production line, and the aqueous phase liquid discharged from the secondary oil-water separator is acidic water containing hydrogen sulfide.

[0014] The beneficial effects of the present invention are:

[0015] The utility model provides a top circulation reflux salt washing system, which first injects water into the mixer through a water injection pump to desalt the top circulation oil entering the mixer from the coking distillation tower, and then uses a first-level oil-water separator, a gas-liquid separator and a second-level oil-water separator in sequence to separate the three-phase mixed liquid of oil, water and gas discharged from the mixer, and the oil phase separated by the first-level oil-water separator and the second-level oil-water separator is transported to the coking distillation tower to participate in the top circulation of the coking distillation tower again, and the water phase separated by the second-level oil-water separator is re-injected into the mixer, and the top circulation oil in the mixer is desalted again, so as to effectively prevent the top tower plate of the coking distillation tower caused by ammonium chloride crystallization from being blocked while improving the recovery rate of the top circulation oil and reducing the water consumption for desalting. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0017] Figure 1 This is a schematic diagram of the connection relationship of the top circulation reflux salt washing system in Example 1.

[0018] In the figure, 1-coking distillation tower, 2-mixer, 3-first-stage oil-water separator, 4-gas-liquid separator, 5-second-stage oil-water separator, 6-water injection pump, 7-second flow meter, 8-regulating valve, 9-safety valve. DETAILED DESCRIPTION

[0019] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the following will be combined with the drawings of the embodiments of the present invention to clearly and completely describe the technical solutions of the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0020] Example 1

[0021] A top circulation reflux salt washing system, such as Figure 1 As shown, the system includes a coking fractionating tower 1. The top circulating oil outlet located at the top of the coking fractionating tower 1 is connected to the feed inlet of the mixer 2 via an oil pipeline. A first flowmeter and a circulating pump are installed on the oil pipeline. The coking tank recycled water source is connected to the inlet of the water injection pump 6 via a pipeline. A pressure gauge is installed at the inlet of the water injection pump 6. The outlet of the water injection pump 6 is connected to the feed inlet of the mixer 2 via a water pipeline. A second flowmeter 7 and a regulating valve 8 are installed on the water pipeline. The discharge port of the mixer 2 is connected to the inlet of the first-level oil-water separator 3 through a pipeline, the oil discharge port of the first-level oil-water separator 3 is connected to the reflux port arranged at the top of the coking fractionation tower 1 through a pipeline, the water outlet of the first-level oil-water separator 3 is connected to the inlet of the gas-liquid separator 4 through a pipeline, a safety valve 9 is arranged on the top of the first-level oil-water separator 3, the exhaust port of the safety valve 9 is connected to the inlet of the gas-liquid separator 4, and the inlet of the gas-liquid separator 4 is also connected to the top circulating oil outlet at the top of the coking fractionation tower 1 through an oil and gas transmission pipeline, and a distillation tower top air cooler and a distillation tower top aftercooler are arranged in sequence on the oil and gas transmission pipeline. The liquid discharge port of the gas-liquid separator 4 is connected to the inlet of the water injection pump 6 and the inlet of the secondary oil-water separator 5 through pipelines via a three-way valve. The oil discharge port of the secondary oil-water separator 5 is connected to the reflux port at the top of the coking fractionation tower 1. The water discharge port of the secondary oil-water separator 5 is connected to the inlet of the water injection pump 6 and the inlet of the pretreatment device of the sulfur production line. The exhaust port of the gas-liquid separator 4 is connected to the hydrogen production unit, and an absorption stabilization unit is installed between the exhaust port of the gas-liquid separator 4 and the hydrogen production unit.

[0022] Working principle: First, use the water injection pump and the circulating pump to pump the coking tank recycled water and the top circulating oil from the top of the coking fractionation tower into the mixer for mixed desalination to obtain an oil-water mixture. During the mixed desalination process, soluble salts such as ammonium chloride in the top circulating oil dissolve in the coking tank recycled water. When the top circulating oil needs to be further desalted, the water injection pump can be used to pump the desalted water with a lower salt content into the mixer for desalination. The oil-water mixture is then transported to the first-level oil-water separator for the first oil-water separation to obtain first-level top circulating oil and first-level salt water. During the process of using the first-level oil-water separator for the first oil-water separation, the pressure in the first-level oil-water separator can be maintained stable by a safety valve. When the pressure in the first-level oil-water separator is higher than the preset pressure, the safety valve can be opened to release the gas in the first-level oil-water separator into the gas-liquid separator. The primary top-cycle oil re-enters the coking fractionator to participate in the top circulation of the coking fractionator. The primary salt water enters the gas-liquid separator and undergoes gas-liquid separation with the oil and gas output from the top of the coking fractionator, producing a gas phase and degassed salt water. After treatment in the absorption stabilization unit, the gas phase enters the hydrogen production unit to participate in hydrogen production. The degassed salt water enters the secondary oil-water separator for a second oil-water separation, producing secondary top-cycle oil and acidic water containing hydrogen sulfide. The degassed salt water can also be pumped into the mixer via a water injection pump to be mixed with the newly entered top-cycle oil for desalination. The secondary top-cycle oil re-enters the coking fractionator to participate in the top circulation of the coking fractionator. The acidic water containing hydrogen sulfide can also be pumped into the mixer via a water injection pump to be mixed with the newly entered top-cycle oil for desalination. It can also be transported from the sulfur production line's pretreatment unit inlet to the sulfur production line for reuse.

[0023] Although the present invention has been described in detail with reference to the accompanying drawings and in conjunction with preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, persons of ordinary skill in the art may make various equivalent modifications or substitutions to the embodiments of the present invention, and such modifications or substitutions shall fall within the scope of the present invention. Any changes or substitutions that can be easily conceived by persons skilled in the art within the technical scope disclosed in the present invention shall fall within the scope of protection of the present invention.

Claims

1. A top circulation reflux salt washing system, comprising a coking fractionation tower, characterized in that: The top circulating oil outlet of the coking fractionating tower and the outlet of the water injection pump are respectively connected to the feed port of the mixer, the discharge port of the mixer is connected to the inlet of the first-stage oil-water separator, the drain port of the first-stage oil-water separator is connected to the inlet of the gas-liquid separator, and the drain port of the gas-liquid separator is connected to the inlet of the second-stage oil-water separator; Among them, the oil discharge port of the first-level oil-water separator and the oil discharge port of the second-level oil-water separator are both connected to the reflux port of the coking distillation tower; the drain port of the second-level oil-water separator is connected to the inlet of the water injection pump.

2. A top circulation reflux salt washing system according to claim 1, characterized in that: The top circulating oil outlet and reflux port of the coking fractionation tower are both arranged at the top of the coking fractionation tower.

3. A top circulation reflux salt washing system according to claim 1, characterized in that: The inlet of the water injection pump is connected to the recycled water from the coking tank.

4. A top circulation reflux salt washing system according to claim 1, characterized in that: The exhaust port of the gas-liquid separator is connected to the hydrogen production device.

5. A top circulation reflux salt washing system according to claim 1, characterized in that: The liquid discharge port of the gas-liquid separator is also connected to the inlet of the water injection pump.

6. A top circulation reflux salt washing system according to claim 1, characterized in that: The drain outlet of the secondary oil-water separator is also connected to the inlet of the pretreatment device of the sulfur production line.

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