A liquid-liquid separator for safe and efficient separation of hazardous chemical mixtures

Abstract

The present invention relates to a liquid-liquid separator for the safe and efficient separation of hazardous chemical mixtures. The present invention comprises a liquid-liquid separator tank, a wire mesh demister, a coalescing plate group, a liquid discharge control device and a measurement and control system; the wire mesh demister and the coalescing plate group are located in the liquid-liquid separator tank; wherein the wire mesh demister is used to achieve foam elimination of the hazardous chemical mixture to be separated; the coalescing plate group is used to make the fluid flow state of the unstratified two-phase mixture alternate between laminar flow and turbulent flow; the liquid discharge control device is used to achieve real-time separation of the hazardous chemical mixture with an unknown two-phase volume ratio. The present invention installs a fishbone-shaped coalescing plate in the middle section of the liquid-liquid separator to make the fluid flow state of the unstratified two-phase mixture alternate between laminar flow and turbulent flow, which is beneficial to the mutual collision and agglomeration between the two-phase droplets, thereby improving the separation efficiency and rate of hazardous chemicals in the liquid-liquid separator.

Description

Technical Field

[0001] The present invention relates to the field of safe separation of hazardous chemicals, and more specifically to a liquid-liquid separator for safely and efficiently separating a mixture of hazardous chemicals. Background Art

[0002] Hazardous chemical mixtures mainly come from the processing, refining, and storage of chemicals; the cracking and purification of oil in the petroleum industry; and leakage during the transportation of chemicals. At present, most hazardous chemical mixtures have large volume ratios of the two media, a wide range of viscosities, and are prone to volatilizing flammable, explosive, or toxic and harmful gases. The above problems make it difficult to improve the recovery rate of hazardous chemical mixtures, and the recovery cost remains high.

[0003] Liquid-liquid separators are important process equipment in chemical production. At present, gravity sedimentation liquid-liquid separators are common in the industry. Their internal structure is simple, and the accumulation speed of two-phase droplets is too slow, resulting in too long natural gravity sedimentation time, making the volume of the liquid-liquid separator too large, which is not suitable for many industrial production and sudden emergency on-site disposal situations. Therefore, some liquid-liquid separators increase the separation rate by adding a coalescing plate inside the separator, but the common coalescing plate has limited separation efficiency when dealing with more viscous and high flow conditions, and is prone to wear and breakage, which in turn blocks the internal pipelines of the liquid-liquid separator.

[0004] Common liquid-liquid separators in industry are usually designed for liquid outlets when the ratio of the two-phase media is relatively fixed. Such designs make it impossible for common liquid-liquid separators in industry to effectively separate some media with non-fixed two-phase volume ratios. Common hazardous chemical mixtures are mostly produced from industrial production, transportation and storage processes, and usually do not have a clear two-phase volume ratio.

[0005] Common liquid-liquid separators in industry are generally suitable for oil-water separation conditions, but the anti-corrosion design of the wire mesh demister in the liquid-liquid separator is neglected. When dealing with complex hazardous chemical mixture media, the wire mesh made of commonly used metal materials has poor corrosion resistance, short service life, and high later maintenance costs. Although the wire mesh made of non-metallic materials has good stability and can cope with a variety of hazardous chemical mixture environments, it has low mechanical strength and is prone to deformation when dealing with large flow and high flow rate conditions for a long time, resulting in adverse changes in the wire mesh grid spacing, reduced liquid pass rate, and thus affecting the defoaming efficiency. In summary, the current design of the wire mesh demister in the liquid-liquid separator is not suitable for the separation conditions of hazardous chemical mixtures for a long time.

[0006] The common liquid-liquid separators in industry generally ignore the volatility of the medium to be separated during the separation process. In the separation project for hazardous chemical mixtures, taking alkane fuels as an example, when alkane fuels are left standing in the liquid-liquid separator, they are very likely to volatilize flammable and explosive alkane gases. The separation standing time of the liquid-liquid separator is generally around 30 minutes. During this period, the concentration of flammable and explosive gases in the liquid-liquid separator is at risk of reaching the explosion limit. At this time, if there are external risk factors such as high temperature, it is very easy to cause major safety accidents. Summary of the invention

[0007] In view of the deficiencies of the prior art, the present invention provides a liquid-liquid separator which is safer, more effective and more efficient for dealing with various hazardous chemical media.

[0008] The objective of the present invention is achieved through the following technical solutions:

[0009] The present invention comprises a liquid-liquid separator tank, a wire mesh demister, a coalescing plate group, a liquid outlet control device and a measurement and control system;

[0010] The wire mesh demister and the coalescing plate assembly are located in the liquid-liquid separator tank;

[0011] in,

[0012] The wire mesh demister is used to eliminate the foam of the mixture containing hazardous chemicals to be separated;

[0013] The coalescing plate group is used to change the fluid flow state of the unstratified two-phase mixture alternately between laminar flow and turbulent flow;

[0014] The liquid outlet control device is used to achieve real-time separation of a mixture containing hazardous chemicals with an unknown two-phase volume ratio;

[0015] The measurement and control system is used to monitor the temperature and pressure in the liquid-liquid separator during the static separation process of the mixture containing hazardous chemicals, as well as the concentration of flammable and explosive gases and toxic and harmful gases in the liquid-liquid separator after the hazardous chemicals volatilize.

[0016] Beneficial effects of the present invention:

[0017] The present invention greatly improves the service life and defoaming efficiency of the wire mesh demister by installing a corrosion-resistant wire mesh demister at the inlet end of the liquid-liquid separator, so that the liquid-liquid separator can be suitable for separating corrosive media, effectively improving the working range of the liquid-liquid separator.

[0018] The present invention installs a fishbone-shaped coalescing plate in the middle section of the liquid-liquid separator to make the fluid flow state of the unstratified two-phase mixture alternate between laminar flow and turbulent flow, which is beneficial to the mutual collision and agglomeration of the two-phase droplets, thereby improving the separation efficiency and rate of hazardous chemicals in the liquid-liquid separator.

[0019] The present invention realizes real-time separation of a mixture containing hazardous chemicals with an unknown two-phase volume ratio by a liquid-liquid separator by installing solenoid valves at the heavy phase medium outlet and the light phase medium outlet of the liquid-liquid separator, combining the feedback signal of a magnetostrictive liquid level meter and embedding an algorithm.

[0020] The present invention achieves the goal of improving the safety of the liquid-liquid separator during operation by installing a measurement and control system above the tank body of the liquid-liquid separator to monitor the pressure, temperature and gas concentration signals in the tank body, and controlling the concentration of flammable and explosive gases and toxic and harmful gases in the liquid-liquid separator within a safe concentration range through an inert gas spray device. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] For ease of explanation, the present invention is described in detail with reference to the following preferred embodiments and the accompanying drawings.

[0022] Figure 1 A schematic diagram of the structure of a liquid-liquid separator for safely and efficiently separating a mixture of hazardous chemicals according to an embodiment of the present invention;

[0023] Figure 2 A schematic structural diagram of a wire mesh demister of a liquid-liquid separator for safely and efficiently separating a mixture of hazardous chemicals according to an embodiment of the present invention;

[0024] Figure 3 A wire cross-sectional view of a wire mesh demister of a liquid-liquid separator for safely and efficiently separating a mixture of hazardous chemicals according to an embodiment of the present invention;

[0025] Figure 4 A schematic diagram of a top view of a fishbone-shaped coalescing plate assembly of a liquid-liquid separator for safely and efficiently separating a hazardous chemical mixture according to an embodiment of the present invention;

[0026] Figure 5 A schematic axial cross-sectional view of a fishbone-shaped coalescing plate assembly of a liquid-liquid separator for safely and efficiently separating a hazardous chemical mixture according to an embodiment of the present invention;

[0027] Figure 6 This is a schematic diagram of the structure of the measurement and control system of the liquid-liquid separator for safely and efficiently separating a hazardous chemical mixture according to an embodiment of the present invention. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] The following is a further detailed description of a liquid-liquid separator for dealing with a variety of hazardous chemical media provided by the present invention in conjunction with the accompanying drawings and specific implementation schemes.

[0030] See also Figure 1 The present application provides a liquid-liquid separator for safely and efficiently separating a mixture of hazardous chemicals. The liquid-liquid separator is used in industry to separate two-phase media that are immiscible and have obvious stratification. It is particularly suitable for the case where the volume ratio of the two-phase media is not fixed, the separation medium is volatile, and there is a risk of being flammable and explosive. It is used to extract the required hazardous chemicals from a mixture containing hazardous chemicals produced due to various abnormal reasons for subsequent treatment.

[0031] Among them, the liquid-liquid separator for safe and efficient separation of hazardous chemical mixtures includes five parts: a tank body 1, a wire mesh demister 2, a herringbone-shaped coalescing plate group 3, a liquid outlet system 4, and a measurement and control system.

[0032] The present invention achieves storage of a mixture containing hazardous chemicals to be separated through a tank body 1, and the tank body 1 is made of a special stainless steel material with high rigidity to improve the pressure resistance of the entire tank body; the inner surface of the liquid-liquid separator is processed with a corrosion-resistant coating, which greatly improves the service life of the liquid-liquid separator tank body and can cope with more separation conditions of hazardous chemicals of different properties.

[0033] In one embodiment, the internal effective dimensions of the tank body 1 are an inner diameter of 700 mm and a length of 2800 mm. One end of the liquid inlet pipeline 11 is connected to the tank body flange 12 and is connected to the front pipeline by a flange connection. The other end is fixed to one side of the tank body by head welding.

[0034] Preferably, a curved transparent glass visualization panel 13 with a diameter of 750 mm, a width of 200 mm and an arc of 160° is embedded and installed on the front side of the tank body 1, providing an intuitive way to observe the liquid level when the liquid-liquid separator separates and purifies hazardous chemicals.

[0035] In one embodiment, a relief valve 14 with a lower relief pressure is installed on the top of the tank body 1. The relief pressure of the relief valve 14 may be selected but is not limited to 50 kPa, which is used to ensure that the pressure in the tank body 1 is always within the safe pressure resistance threshold and effectively improve the service life of the tank body 1.

[0036] In addition, four tank sensor interfaces 15 are distributed on the top of the tank body 1, namely a temperature sensor interface 151, a pressure sensor interface 152, a gas concentration sensor 153, a magnetostrictive level gauge interface 154, and an inert gas nozzle interface 155, which can be sealed to install sensors for monitoring various physical parameters in the tank body 1.

[0037] See also Figure 2The present application realizes foam elimination of the mixture containing hazardous chemicals to be separated through a wire mesh demister 2, wherein the wire mesh demister 2 is composed of a mesh 22 woven from silk threads 21 and a mesh fixing device 23, and the mesh 22 is fixed to the outlet of the liquid inlet pipeline 11 of the tank body 1 through the mesh fixing device 23.

[0038] Furthermore, the wires 21 are distributed in a periodic harmonic manner to form the mesh 22, and the intervals between the wires are 5-8 mm. This interval ensures that the mesh has good rigidity and effectively ensures that the mesh has a good passing rate.

[0039] See also Figure 3 In one embodiment, the outside of the wire 21 is wrapped with a non-metallic material 212, such as a perfluoroalkoxy resin, to protect the metal core of the wire 21 and prevent the corrosive fluid from corroding the wire 21. The metal core of the wire is composed of corrosion-resistant stainless steel filaments 211, which provide rigid support for the wire 21 to prevent the mesh 22 from being deformed due to excessively fast scouring of the medium to be separated, resulting in a decrease in the pass rate. In addition, the surface of the perfluoroalkoxy resin material is smooth, and the mixture of hazardous chemicals to be separated is not easy to remain on the surface of the mesh 22, which is conducive to improving the service life and defoaming efficiency of the mesh 22.

[0040] See also Figure 1 and Figure 4 In a certain embodiment, the fishbone-shaped coalescing plate group 3 can make the fluid flow state of the unstratified two-phase mixture alternate between laminar flow and turbulent flow, which is beneficial to the collision and agglomeration of the two-phase droplets, and is beneficial to improving the separation efficiency and rate of hazardous chemicals in the liquid-liquid separator.

[0041] See also Figure 1 The fishbone-shaped coalescing plate group 3 is composed of a plurality of evenly spaced coalescing plates. The downward inclination angle α of the fishbone-shaped coalescing plate group 3 in the horizontal direction is preferably 15° to 20°, which helps the mixture containing hazardous chemicals to be separated to flow to the subsequent structure under the action of gravity.

[0042] See also Figure 4 The agglomeration plate is evenly distributed with herringbone corrugated baffles with a height h of 2 to 3 cm, and the angle β between the herringbone baffles along the direction of the fishbone-shaped agglomeration plate group 3 is 25° to 30°. The agglomeration plate is provided with corrugations on both sides of the axis along the flow direction of the hazardous chemical mixture to be separated, and the corrugations on the same side form a certain angle with the axis direction, and the angle γ between the corrugations and the axis direction is about 40° to 60°. Too large an angle will cause the hazardous chemical mixture to be separated to encounter too much resistance when flowing on the fishbone-shaped agglomeration plate group 3, and accordingly, the degree of erosion and wear of the fishbone-shaped agglomeration plate group will be deepened, the damage of the fishbone-shaped agglomeration plate group will be accelerated, and the reflux phenomenon will be obvious, affecting the separation efficiency and rate; too small an angle will lead to an unclear agglomeration effect, affecting the separation efficiency.

[0043] In order to verify the above design, this application further provides the following simulation experiments:

[0044] When the liquid-liquid separator for safely and efficiently separating hazardous chemical mixtures is used to separate immiscible liquids with different specific gravities, a numerical simulation of the separation performance of the liquid-liquid separator for safely and efficiently separating hazardous chemical mixtures is performed.

[0045] The simulation calculation was performed based on ANSYS Workbench 2023R1. The calculation conditions are as follows: the liquid mixture is made of refined petroleum (density 900kg / m 3 , dynamic viscosity 0.85Pa·s) and water (density 1000kg / m 3 , dynamic viscosity 0.04Pa·s).

[0046] The inlet condition is set as velocity boundary, and the inlet velocity is 1.2 m / s; the oil and water outlets are both set as outflow outlets; and the water-oil two-phase ratio is 8:2.

[0047] The results show that the separation recovery rate of the liquid-liquid separator with the fishbone-shaped coalescing plate group 3 is higher than that of the liquid-liquid separator with a conventional corrugated coalescing plate group structure. The light phase recovery rate of the conventional corrugated coalescing plate group liquid-liquid separator is about 0.8, while the light phase recovery rate of the fishbone-shaped coalescing plate group liquid-liquid separator of the present invention reaches 0.92. It is proved that the improvement of the coalescing plate group structure can effectively improve the separation recovery rate of the liquid-liquid separator and efficiently separate the light phase medium and the heavy phase medium.

[0048] See also Figure 1 In a certain embodiment, the liquid outlet control system 4 for coping with various hazardous chemical media includes a light phase medium outlet 41, a light phase medium outlet solenoid valve 42; a heavy phase medium outlet 43, a heavy phase medium outlet solenoid valve 44; a light phase medium outlet pipeline 45, a heavy phase medium outlet pipeline 46, and a magnetostrictive liquid level meter 47 for measuring the highest liquid level in the liquid-liquid separator and the two-phase boundary liquid level. The signal of the magnetostrictive level gauge 47 is collected through the circuit to obtain the distribution of the two-phase medium in the liquid-liquid separator. When the liquid level of the heavy phase medium reaches the preset upper limit height, the heavy phase medium outlet solenoid valve 44 installed on the heavy phase medium outlet pipeline 46 is opened to allow the heavy phase medium sunk to the bottom of the liquid-liquid separator to flow out from the heavy phase medium outlet 43. When the liquid level of the heavy phase medium reaches the preset lower limit height, the heavy phase medium outlet solenoid valve 44 is closed to stop the discharge of the heavy phase medium. This process realizes a single discharge of the separated sample in the liquid-liquid separator. By continuously repeating the above process, real-time separation of a mixture containing hazardous chemicals with an unknown two-phase volume ratio is achieved.

[0049] See also Figure 6In one embodiment, the measurement and control system 5 for dealing with multiple hazardous chemicals includes a pressure sensor 51, a temperature sensor 52, a gas concentration sensor 53, and an inert gas nozzle 54. The above measurement and control systems are centrally distributed at intervals of 20 to 30 cm at the upper end of the liquid-liquid separator, and are used to monitor the temperature and pressure in the liquid-liquid separator during the static separation of the hazardous chemical mixture, as well as the concentration of flammable and explosive gases and toxic and harmful gases in the liquid-liquid separator after the hazardous chemicals volatilize. When it is detected that the concentration of flammable and explosive gases and toxic and harmful gases in the pipeline exceeds the set safety threshold, the inert gas nozzle is turned on to spray inert gas into the liquid-liquid separator. The inert gas spraying rate of the inert gas nozzle 54 is controlled by the gas concentration sensor, and the embedded algorithm controls the concentration of flammable and explosive gases and toxic and harmful gases in the liquid-liquid separator to be within the safe concentration range, thereby improving the safety of the liquid-liquid separator during operation.

[0050] The above is an embodiment of the present invention. It should be pointed out that for ordinary technicians in this field, various modifications and improvements can be made without departing from the principle of the present invention, which should also be regarded as the protection scope of the present invention.

Claims

1. A liquid-liquid separator for safe and efficient separation of hazardous chemical mixtures, characterized in that: It includes a liquid-liquid separator tank, a wire mesh demister, a coalescing plate group, a liquid discharge control device and a measurement and control system; The wire mesh demister and the coalescing plate assembly are located in the liquid-liquid separator tank; in, The wire mesh demister is used to eliminate the foam of the mixture containing hazardous chemicals to be separated; The coalescing plate group is used to change the fluid flow state of the unstratified two-phase mixture alternately between laminar flow and turbulent flow; The liquid outlet control device is used to achieve real-time separation of a mixture containing hazardous chemicals with an unknown two-phase volume ratio; The measurement and control system is used to monitor the temperature and pressure in the liquid-liquid separator during the static separation process of the mixture containing hazardous chemicals, as well as the concentration of flammable and explosive gases and toxic and harmful gases in the liquid-liquid separator after the hazardous chemicals evaporate; The agglomeration plate group is tilted downward in the horizontal direction, which helps the mixture containing hazardous chemicals to be separated to flow to the subsequent structure under the action of gravity; The agglomeration plate group is composed of a plurality of agglomeration plates arranged at intervals, wherein each agglomeration plate is a fishbone-shaped corrugated plate; The corrugated plate is evenly distributed with herringbone corrugated baffles with a height of 2 to 3 cm, and the angle between the herringbone baffles along the direction of the fishbone-shaped agglomeration plate group is 25° to 30°; the corrugated plate is provided with corrugations on both sides of the axis along the flow direction of the hazardous chemical mixture to be separated, and the angle between the corrugations on the same side and the axis direction is 40° to 60°.

2. A liquid-liquid separator for safe and efficient separation of hazardous chemical mixtures according to claim 1, characterized in that: A relief valve is installed on the top of the tank body to ensure that the pressure in the tank body is always within the safe pressure resistance threshold.

3. A liquid-liquid separator for safe and efficient separation of hazardous chemical mixtures according to claim 1, characterized in that: The wire mesh demister is composed of a mesh and a mesh fixing device, and the mesh is woven from corrosion-resistant silk threads in a periodic harmonic manner.

4. A liquid-liquid separator for safe and efficient separation of hazardous chemical mixtures according to claim 3, characterized in that: The outer layer of the wire is wrapped by a corrosion-resistant non-metallic material, and metal filaments are arranged inside.

5. A liquid-liquid separator for safe and efficient separation of hazardous chemical mixtures according to claim 3, characterized in that: The corrosion-resistant non-metallic material is perfluoroalkoxy resin.

6. A liquid-liquid separator for safe and efficient separation of hazardous chemical mixtures according to claim 1, characterized in that: The liquid outlet control system consists of a light phase medium outlet, a heavy phase medium outlet and two solenoid valves. The solenoid valves at the water phase medium outlet and the heavy phase medium outlet are controlled respectively through the interface liquid level height signal fed back by the magnetostrictive liquid level meter, thereby controlling the on and off of the liquid outlet and realizing real-time separation of the liquid-liquid separator.

7. A liquid-liquid separator for safe and efficient separation of hazardous chemical mixtures according to claim 1 or 6, characterized in that: The measurement and control system includes a gas concentration sensor and an inert gas nozzle; When it is detected that the concentration of flammable and explosive gases and toxic and harmful gases in the pipeline exceeds the set safety threshold, the inert gas nozzle is turned on to spray inert gas into the liquid-liquid separator. The inert gas spraying rate of the inert gas nozzle is controlled by the gas concentration sensor.

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