WO2020001246A1 - Method and apparatus for degassing and oil removal of acidic water - Google Patents

Abstract

Disclosed in the present invention is a method and apparatus for degassing and oil removal of acidic water. First, gas carried in acidic water is separated from dissolved gas released by means of pressure decrease; the acidic water is treated by means of centrifugal flash evaporation, a centrifugal flash evaporation ejector being provided at a flash evaporation tank liquid inlet, the gas dissolved at a flash evaporation tank operating pressure is further separated, microbubbles are effectively removed by a centrifugal field in which liquid-gas separation is performed by means of swirling flow, and the gas enters a gas outlet from a gas-phase space; liquid enters a coarse-particle agglomeration module, oil drops flow sinusoidally along with the flow of the liquid, oil moves upwards from the top, and the water moves upwards from the bottom, so as to implement quick oil-water separation; physical demulsification separation is then performed on a part of unseparated emulsified oil droplets by means of a hydrophilic and hydrophobic nano modified fiber module; the separated oil goes to the upper layer of the liquid, enters an oil separation tank through an overflow plate, and then leaves the apparatus, and water flow across the bottom of the oil separation tank, the oil-water boundary line height being controlled by means of a water separator plate.

Description

Method and device for degassing and degreasing acidic water Technical field

The invention relates to a method and a device for degassing and degreasing acidic water, in particular to a compact device using a centrifugal flash deaerator and a series coalescing separator to degas and degrease the original. The device is integrated into a complete set of equipment, which fully utilizes the advantages of centrifugal flash deaerator and series coalescing separation, realizes the process of deep flash separation of gas and oil-water separation, and efficiently and quickly removes dispersed gas and emulsified oil It also eliminates the problem of inaccurate oil-water boundary measurement in the conventional sedimentation tank by using a level gauge, and meets the requirements of subsequent acidic water stripping.

Background technique

In the petroleum industry, natural gas chemical industry, coal chemical industry and other processes, the sulfur recovery device is an indispensable device. Its role is to recover sulfur and produce sulfur in the chemical process by using appropriate processes to achieve cleanliness. The purpose of production and environmental protection, and at the same time to meet product quality requirements, reduce corrosion, and achieve long-term safety production of the device and many other requirements. Hydrogen sulfide in acidic water is one of the important sources of sulfur recovery for acid gas. The higher the cleanliness of acid gas, the more stable the sulfur recovery device will operate.

Generally, the raw material water processed by the acidic water stripping unit comes from the sulfur-containing sewage in each unit of the site. Due to the pressure, some light hydrocarbons, light oil and heavy oil will be dissolved in the sulfur-containing sewage. If it is good, it will affect subsequent operations. If the hydrocarbons in the raw water are not removed, the hydrocarbons will be stripped out when the raw water enters the stripper, which will affect the H ₂ S removal rate and the quality of the acid gas. Hydrocarbons, light oils, and H2S enter the subsequent sulfur plant, and the area of carbon in the burner will affect the life cycle of the sulfur burner. The heat value of the hydrocarbons is relatively high, which will lead to overheating of the reaction furnace after entering the sulfur plant. Hydrocarbons and light oils will increase a lot of side reactions after entering the sulfur reactor, and even produce "black sulfur". The substances such as COS and CS2 will not be absorbed by the amine solution, and eventually enter the incinerator to be incinerated to SO2, resulting in excessive emissions , Or enter the flue gas desulfurization device to increase the consumption of absorption liquid.

In addition, if the oil in the acidic water is not removed, it will be taken to the stripping tower, and the heating will form an oil seal on the tray. The top temperature is less than the pressure fluctuation, which affects the quality of the acid gas. The heavy oil enters the purified water and causes the purified water to fail. . At the same time, the raw water with oil will cause frequent punching towers, causing fluctuations in the temperature, pressure and liquid level of the stripping tower, which will seriously affect the stable operation of the stripping.

Chinese invention patent CN104310685A discloses an acidic water treatment device and method, which uses a degreasing and degassing unit and an acidic water storage unit to effectively separate the dissolved gas in acidic water through a pressure reduction method. The method of gravity settlement is divided into gas phase and liquid phase, but the gas and some micro bubbles that are still dissolved in acidic water under this pressure cannot be separated, and will still be taken to the downstream device, resulting in an increased load on the downstream device.

Chinese invention patent CN105174520A discloses an acidic water degreasing treatment method, which is floated out through a homogeneous floating oil receiver, and the water discharged after separation and precipitation is subjected to a cyclone oil-water separator for oil-water separation. However, this process method is complicated, requiring a homogeneous floating oil receiver, a large area, and the cyclone oil separator can only separate oil-water systems with relatively large density differences and not severe emulsification, and cannot effectively separate emulsified oil droplets. .

In the current acidic water pretreatment degassing and degreasing, there is an urgent need for a complete set of equipment that achieves deep separation of degassing and degreasing, low energy consumption, and low operating costs.

Summary of the invention

In order to overcome the above-mentioned shortcomings of the prior art, the present invention proposes a technology utilizing the coupling of centrifugal flash degassing and stepwise degreasing to remove the gas carried by pressurized acidic water and the dissolved gas and acidic water carried by the partial pressure. Method and equipment for efficient separation of large and small oil droplets. The present invention makes up for the problems of current acidic water degassing tanks with insufficient effects, large tanks with long settling time, large floor space, and the problems of inaccurate measurement of oil and water level gauges of conventional degassing and degreasing tanks.

The specific technical solution of the present invention is as follows:

The first aspect of the present invention provides a method for degassing and degreasing acidic water. Step 1. The first step is to enter the flash deaerator with a gaseous oily acidic water under the action of gravity. Dissolve the dissolved gas; step 2, use the method of centrifugal flash to treat the acidic water, set a centrifugal flash ejector at the liquid inlet of the flash tank, and rely on the pressure gradient field of the swirling liquid-gas separation (radial section from outside to in The pressure is gradually reduced.) The gas dissolved under the operating pressure of the flash tank is further separated, and the micro-bubbles are effectively removed by the centrifugal field of the swirling liquid-gas separation, and the gas enters the gas outlet from the gas phase space; Step 3, the liquid phase enters the coarse particles. The coalescing module increases the chance of small oil droplets colliding so that the particle size of the oil droplets continues to grow. After growing up, the oil droplets pass through the enhanced gravity sedimentation module. The oil droplets flow sinusoidally with the flow of the liquid, and the oil phase changes from The top moves up and the water phase moves down from the bottom, forming a rapid separation of oil and water. Partially emulsified, unseparated small oil droplets are then physically demulsified and separated through the hydrophilic-hydrophobic nano-modified fiber module; Step 4. The separated oil reaches the upper layer of the liquid phase, enters the oil trap through the overflow plate, and exits the device. The water flows through the bottom of the oil separation tank, and the oil-water boundary level is controlled by the water-phase partition, eliminating the use of the oil-water boundary gauge.

Further, said:

Step 1: Under the action of the gravity field, firstly separate the dissolved gas released by the acidic water carrying gas and pressure drop. The pressure of the acidic water with gas and oil is 0.1 ～ 20MPa, the pressure drop is 0.01 ～ 19.95MPa, and the processing temperature is 5 ~ 99 ℃;

Step 2: The centrifugal flash degassing method is used to perform a second gas-liquid separation of the acidic water by relying on the pressure gradient field generated by the centrifugal force. The pressure difference within the centrifugal force is 0.01 to 0.2 MPa, and the processing temperature is 5 to 99 ° C.

Step 3: The coalesced physical degreasing and separation method is used to separate the free, suspended, and emulsified oil droplets in the degassed acidic water; the pressure drop during the separation is 0.001 to 0.05 MPa;

Step 4: After the oil and water separated in step 3, the oil overflows into the oil phase collection tank, and is periodically discharged through the liquid level controller. Water flows through the bottom of the oil phase collection tank, and then passes through the water phase separator and passes the liquid level control. Drain and control the oil-water boundary in front of the oil phase collection tank through the water phase separator.

According to another aspect of the present invention, an acidic water degassing and degreasing device is provided. The centrifugal flash degassing and degreasing device includes a shell, and a national anthem installed in the shell is connected with the centrifugal flash degassing core tube in parallel, and the shell is arranged on the shell. The multi-stage degreasing module inside is provided with an inlet, a liquid level gauge, a differential pressure gauge, a liquid phase outlet, and a gas phase outlet provided on the shell. The centrifugal flash degassing core tube includes a cavity, and the cavity is provided with a core. Tube liquid gas inlet, core tube gas phase outlet and core tube liquid phase outlet. The distance between the coarse-grained degreasing module and the centrifugal flash degasser is 300-2000mm, and the distance between the enhanced gravity settlement module and the coarse-grained degreasing module. At 50mm, the hydrophilic-hydrophobic nano-modified fiber module is 200-1800mm away from the oil phase outlet.

The acidic water degassing and degreasing device includes the following components:

(1) Centrifugal flash evaporation for separation of hydrocarbon gas, H ₂ S and NH ₃ dissolved in acidic water by means of a pressure gradient field of swirling liquid-gas separation (radial section gradually decreases in pressure from outside to inside) Degasser

(2) A coarse-grained module for rapidly agglomerating and growing oil droplets in a free, dispersed, and suspended state through a packed bed composed of solid materials that are lipophilic on the surface;

(3) Enhanced gravity sedimentation module for oil droplets that grow up to perform variable-speed movement along the corrugated plate, and then quickly separated through small holes with a certain ratio of peaks and troughs;

(4) Hydrophobic nano-modified fiber module for weaving and combining by Ω form, suitable for 0.1-20μm droplet separation;

(5) The baffle used to control the oil collection. The front baffle of the oil collecting tank is lower than the rear baffle, and the water phase partition is lower than the front baffle of the oil collecting tank.

Further, the centrifugal flash deaerator is set at the entrance of the equipment, and is 800mm-1500mm away from the bottom of the tank;

Further, the flow rate in the centrifugal flash deaerator is 0.8m / s-1.2m / s;

Further, the inlet diameter of the core tube of the centrifugal flash deaerator is 50-100 mm, and the diameter of the gas phase outlet is 10-30 mm.

Further, the material used for the coarse-grained module is a material that is lipophilic and hydrophobic on the surface, that is, the contact angle between the oil and solid surfaces should be less than 70 °, and the smaller the contact angle, the better the lipophilic wetting performance;

Further, the enhanced gravity sedimentation module is arranged after the coarse-grained module, and the oil floats to the upper layer of the folding plate through the small holes opened at a certain ratio by the crests and troughs. In this way, the layers can float up or down;

Further, the hydrophilic-hydrophobic nano-modified fiber module is arranged after the enhanced gravity sedimentation module, and the design value of the interface flow velocity is between 0.002 and 0.2 m / s;

Further, the front baffle of the oil collecting tank is about 100-600 mm lower than the rear baffle, and the water-phase partition plate is 50-300 mm lower than the front baffle of the oil collecting tank.

Compared with the prior art, the method and device for degassing and degreasing acidic water provided by the present invention have the following advantages:

(1) Compared with the traditional degassing tank, the degassing equipment provided by the present invention has a fast processing speed and high degassing efficiency; it overcomes the problem that the acid gas carries hydrocarbons into the subsequent stripping device, causing the subsequent device to fluctuate greatly;

(2) Compared with the traditional degreasing tank, the degreasing equipment provided by the present invention has high degreasing efficiency, simple operation, and small equipment volume; it overcomes the problems of long tank settlement time, large floor area, and poor degreasing effect.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic structural diagram of degassing and degreasing of acidic water.

In the figure: 1- gas phase outlet; 2- gas-liquid two-phase inlet; 3- centrifugal flash degasser distribution tube; 4- centrifugal flash degasser; 5- coarse graining module; 6- enhanced gravity sedimentation module; 7-hydrophilic fiber module; 8- oil collecting tank; 9- liquid level gauge; 10- oil phase outlet; 11- baffle; 12- water phase outlet; 13- tank.

detailed description

After extensive and in-depth research, the inventors of the present invention have found that for flash degassing and degreasing of acidic water, the more conventional method is to use gravity sedimentation flash degassing and large tank degreasing. In actual production, gravity settling flash degassing tanks have problems such as low degassing efficiency and poor layering effect of acidic water and oil phase. Therefore, the invention adopts the technology of centrifugal flash degassing and coalescing and degreasing, and the centrifugal flash deaerator and degreasing module set are built in the acidic water degassing and degreasing tank, using the centrifugal force of the swirling field and reducing the pressure. Flash evaporation, strengthen the degassing of acidic water, and use a three-layer degreasing module to quickly remove oil. Therefore, the problems of low degassing efficiency of the current degassing tank, incomplete degreasing of the degreasing tank, and large area are effectively solved, and the degassing and degreasing efficiency of the acid water is improved.

Method and steps for degassing and degreasing acidic water

Step 1: Under the action of gravity field, firstly separate the dissolved gas released by the acidic water carrying gas and pressure drop. The pressure of the acidic water with gas and oil is 0.1 ～ 20MPa, the pressure drop is 0.05 ～ 19.95MPa, and the processing temperature is 5 ~ 99 ℃;

Step 2: The centrifugal flash degassing method is used to rely on the pressure gradient field generated by the centrifugal force to perform a second gas-liquid separation of the acidic water. The pressure difference in the centrifugal force is 0.02 to 10.02 MPa, and the processing temperature is 5 to 99 ° C.

Step 3: The coalesced physical degreasing and separation method is used to separate the free, suspended, and emulsified oil droplets in the degassed acidic water; the pressure drop during the separation is 0.001 to 0.05 MPa.

According to another aspect of the present invention, a device for degassing and degreasing acidic water is provided. The device includes:

The inlet of the tank 13 is equipped with a distribution pipe 3 for distributing acid water into the centrifugal flash degasser 4 and the gas phase outlet 1. The tank 13 has a built-in coarse granulation module 5, an enhanced gravity sedimentation module 6, and a hydrophobic fiber. Module 7; the tank body 13 is internally provided with an oil separation tank 8 and an oil drain port 10 for separating an oil phase; the tank body 13 further includes a partition plate 11 and an aqueous phase outlet 12 for water phase overflow; the tank The centrifugal flash degasser 4 at the inlet of the body 13 is mounted on the distribution pipe 3, and its inlet is in communication with the distribution pipe.

In the process of a petrochemical acid water stripping device, according to the method of the present invention, the method and device for degassing and degreasing acidic water is used to perform centrifugal strengthening of the flashing process of acidic water to deeply remove entrained hydrocarbons. Coalescing and degreasing method has effectively separated oil in acid water. The specific operation process and effect are described as follows:

1. Material properties and related parameters

Acidic water treatment capacity is 140m ³ / h, operating temperature is 40 ° C, acidic water density is 700kg / m ³ under operating conditions, oil content is 3000-5000ppm under operating conditions, and operating pressure is 1.1MPa.

2. Implementation process

With reference to the method of the present invention, the details are as follows:

The acidic water enters the centrifugal flash degasser distribution pipe through the inlet of the acidic water degassing and degreasing device, and the gas phase dissolved in the liquid phase is subjected to centrifugal flash separation. The flashed gas phase is degassed and degreased from the acidic water through the gas phase space. The gas phase outlet of the generator enters the gas pipe network.

After the degassed acid water enters the coalescing degreasing module, the oil and water are layered. The oil phase overflows into the oil trap through the upper layer, and the oil is discharged from the oil phase outlet of the oil trap. The water phase enters the degassing and dehydration through the separator. The water phase outlet of the oil tank goes to the downstream device.

3. Implementation effect

(1) Hydrocarbon removal effect

After the acidic water centrifugal flash deaerator treatment, the gas phase hydrocarbon removal rate in the acidic water reaches 98%.

(2) Oil removal effect

After being processed by the acidic water coalescing and degreasing module, the petroleum content in the water phase outlet is less than or equal to 80 ppm.

In summary, the above is only a preferred embodiment of the present invention, and is not intended to limit the implementation scope of the present invention. That is, all equivalent changes and modifications made according to the content of the patent application scope of the present invention shall belong to the technical scope of the present invention.

Claims (9)

A method for degassing and degreasing acidic water, characterized in that the steps are as follows: Step 1. The oily acidic water with gas enters the flash degasser in the first step, and the dissolved gas released by the acidic water and the pressure drop is first separated under the action of gravity field; Step 2. The gas dissolved under the operating pressure of the degassing tank is subjected to secondary separation using a centrifugal pressure gradient field generated by a centrifugal flash degassing method, so that the tiny bubbles entrained in the acidic water can be effectively removed, and the separated gas enters Gas phase space back-out device; Step 3. The degassed acidic water enters the liquid phase space from the bottom of the centrifugal flash degasser, and first passes through the coarse-grained coalescing module, and the oil droplets continue to collide and the particle size continues to grow. The oil after growing up The drops pass through the enhanced gravity sedimentation module to perform rapid oil-water separation. Part of the emulsified oil that has not been separated enters the hydrophilic and hydrophobic nano-modified fiber module and is further physically demulsified and separated; Step 4. After the oil and water separated in step 3, the separated oil reaches the upper layer of the liquid phase, enters the oil trap through the overflow plate, and exits the device. Water flows through the bottom of the oil trap, and the oil and water are controlled by the water phase separator. Boundary height. The method for degassing and degreasing acidic water according to claim 1, wherein: Step 1: Under the action of the gravity field, firstly separate the dissolved gas released by the acidic water carrying gas and pressure drop. The pressure of the acidic water with gas and oil is 0.1 ～ 20MPa, the pressure drop is 0.01 ～ 19.95MPa, and the processing temperature is 5 ~ 99 ℃; Step 2: The centrifugal flash degassing method is used to perform a second gas-liquid separation of the acidic water by relying on the pressure gradient field generated by the centrifugal force. The pressure difference within the centrifugal force is 0.01 to 0.2 MPa and the processing temperature is 5 to 99 ° C. Step 3: The coalesced physical degreasing and separation method is used to separate the free, suspended, and emulsified oil droplets in the degassed acidic water; the pressure drop during the separation is 0.001 to 0.05 MPa; Step 4: After the oil and water separated in step 3, the oil overflows into the oil phase collection tank, and is periodically discharged through the liquid level controller. Water flows through the bottom of the oil phase collection tank, and then passes through the water phase separator and passes the liquid level control. Drain and control the oil-water boundary in front of the oil phase collection tank through the water phase separator. An apparatus for degassing and degreasing acidic water according to the method of claim 1 or 2, comprising the casing of the centrifugal flash degassing and degreasing equipment, each of the parallel centrifugal flash degassing core tubes arranged in the shell, arranged at The multi-stage degreasing module in the shell is provided with an inlet, a liquid level gauge, a differential pressure meter, a liquid phase outlet and a gas phase outlet provided on the shell. The centrifugal flash degassing core tube includes a cavity, and the cavity is provided with the cavity. The core tube liquid gas inlet, core tube gas phase outlet and core tube liquid phase outlet. The distance between the coarse-grained degreasing module and the centrifugal flash deaerator is 300-2000mm, and the enhanced gravity settlement module is separated from the coarse-grained degreasing module. The distance is 50mm, and the hydrophilic-hydrophobic nano-modified fiber module is 200-1800mm away from the oil phase outlet. The front baffle of the oil collecting tank is about 100-800mm lower than the rear baffle, and the water phase partition is 50 lower than the front baffle of the oil collecting tank. ‐600mm. The degassing and degreasing device for acidic water according to claim 3, wherein the centrifugal flash degasser is located at the entrance of the equipment and is 800mm-1500mm away from the bottom of the tank. The degassing and degreasing device for acidic water according to claim 3, wherein the coalescing and degreasing form is a coarse-grained module, an enhanced gravity sedimentation module, and a hydrophilic-hydrophobic nano-modified fiber module in a serial manner, The design value of the interfacial velocity is between 0.002 and 0.2 m / s. The degassing and degreasing device for acidic water according to claim 3, characterized in that the core tubes of the centrifugal flash degasser are combined in a parallel manner, the core tube and the collecting tube are flange-connected, and the core tube has a gas phase. The outlet is connected to the gas phase space of the tank body, and the circulation channel is a centrifugal flash degassing core tube group. The device for degassing and degreasing acidic water according to claim 3, wherein the core tube inlet diameter of the centrifugal flash deaerator is 50-300mm, and the gas-phase outlet diameter is 10-100mm. The degassing and degreasing device for acidic water according to claim 3, characterized in that the inlet of the centrifugal flash deaerator is connected to the inlet of acidic water, a coarse-grained module is built in the equipment, and a gravity-gravity sedimentation module is built in the equipment, The hydrophilic and hydrophobic nano-modified fiber module is built in the device, and the three modules are arranged one after another with a certain distance between them. The deaeration and degreasing device for acidic water according to claim 3, characterized in that the front baffle of the oil collecting tank is lower than the rear baffle, the water phase partition is lower than the front baffle of the oil collecting tank, and the front baffle of the oil collecting tank is low The back baffle is about 100-800mm, and the water-phase partition is 50-600mm lower than the front baffle of the oil collecting tank.

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