KR20200024036A - A sf6 refinement system and method including hybrid reactors utilizing gas hydrate formation - Google Patents

Abstract

The present invention is a SF_6 refining system and a SF_6 refining method for collecting, refining, and then recycling contaminated SF_6 gas generated in an electric power industry and, more specifically, to a SF_6 refining system using hydrate formation and a method thereof to efficiently purify a large amount of waste SF_6 by maximally reducing the amount of SF_6 emitted to the atmosphere during purification by using the SF_6 refining system comprising a SF_6 recovery system, a flue gas exhaust system, a SF_6 collection system, a moisture removal system, a water collection system, and a recharging unit.

Description

SF6 purification system using hydrate formation and SF6 purification method using the same {A SF6 REFINEMENT SYSTEM AND METHOD INCLUDING HYBRID REACTORS UTILIZING GAS HYDRATE FORMATION}

The present invention effectively contaminated SF was purified to ₆ gas recovery and recycling SF relates to ₆ tablets and, more particularly lung SF ₆ of the SF ₆ as much as possible to reduce mass to be discharged to the atmosphere in the purification process generated in the power industry The present invention relates to an SF ₆ purification system using hydrate formation, and a SF ₆ purification method using the same.

Sulfur hexafluoride (SF ₆ ) has been around since early 1960 due to insulation withstand times three times higher than air, thermal interruption capabilities ten times higher than air, and high heat transfer performance (twice the air). It has been successfully used in electrical installations such as high and medium voltage switchgears, gas insulated switchgears (GIS), annular main circuits, automotive circuit breakers, transformers and cables.

SF ₆ gas is used in non-electrical industries, including aluminum production, magnesium smelting, semiconductor production, flat screen production, nuclear fuel cycles, noise-proof windows, tires, high performance radar, tracking gases for climate measurement, in power plant pipes and military applications. It is also widely used in other fields. In the non-electric industry, SF ₆ gas is used at a low concentration of about 1%. However, in the electric industry, a high concentration or almost 100% of SF ₆ gas is used, and about 80% of Korea's total SF ₆ consumption is used in the electric industry. In the electrical industry, SF ₆ is used and stored in closed cycles. For example, it is used for GIS, medium voltage, high voltage gas switch, high voltage gas insulated wire, gas insulated voltage transformer, etc.

When arcs occur in appliances in the electrical industry using SF ₆ , ie, normal switch operation or troubleshooting or unexpected internal arc failures, SF ₆ is decomposed and various byproducts are generated continuously. When stressed by temperature, radiation or electrical discharges and fluorine atom separation, many radicals, ions and neutral molecules are produced and most atoms recombine to form SF ₆ , while some form several stable end products. To other materials in the system. Such materials also include oxygen, water and materials used in the manufacture of equipment, in particular. Impurities contained in the waste SF ₆ gas generated in the electric industry through this path include HF, SO ₂ , SOF ₂ , SOF ₄ , SO ₂ F ₂ , SF ₄ , CF _4, etc. Air and oils are known.

SF ₆ gas is recycled without releasing SF ₆ into the atmosphere because its global warming potential (GWP) is very high, 23,900 times that of CO ₂ , and remains undecomposed in the atmosphere for 3,200 years. It is environmentally and economically important to prevent emissions to the atmosphere and to ensure environmentally compatible emissions in a series of processes including development, design, production, service, maintenance and recovery.

To this end, the contaminated SF ₆ gas (hereinafter referred to as 'waste SF ₆ ' or 'waste SF ₆ gas') generated at present industrial sites is liquefied by using adsorption, membrane separation, deep cooling using a freezer or refrigerant, and solidification. Various technologies are being improved or under development, including distillation and gas hydrates.

Adsorption is a method of gas separation that utilizes different adsorption characteristics depending on the material and uses activated carbon, zeolite, and other adsorbents to change pressure changes (Pressure Swing Adsorption, PSA) or temperature swing (TSA). As a technique for separating a given substance, it is easy to manufacture a device and the manufacturing cost is relatively low, but there is a problem in that the size of the device is large and the purity of purified SF ₆ (or fluorinated gas) is low, which limits the size and concentration of the equipment.

In the membrane separation method using a membrane, a hollow fiber membrane based on polysulfone and polyimide is mainly used as a gas separation technique using a gas permeability difference. This technique is useful for concentrating low concentrations of SF ₆ , but for commercialization of high concentration SF ₆ separation and purification techniques using membranes, high-selectivity membrane materials, hollow fiber membrane processing technology, large-area module development, and application-specific processes Need development

SF ₆ separation and refining technology using liquefaction or solidification is a technology that separates and purifies SF ₆ to be separated into a liquid or solid state by using a freezer or liquid nitrogen as a refrigerant. While the time required is short and the purity can be increased, energy is required for liquefaction and solidification, and the entire process is sensitive to temperature and pressure. There are disadvantages.

Distillation is a liquefaction method in which SF ₆ is liquefied at low temperature and then distilled using a distillation column. Distillation methods include a continuous distillation method for continuous distillation again and a batch distillation method for distillation in a batchwise manner. Batch distillation is more advantageous in order to obtain ultra high purity. With distillation, while the advantage of being able to get ultra high purity SF ₆ which can be used in the semiconductor industry, and it takes a lot of system production costs, including the cryogenic distillation column, nor the nature of the device to move the tower easy, the SF _6, and boiling point Similar impurities may be separated, but in this case, the number of stages of the distillation column is increased, so that the height of the distillation column is increased.

Using a gas hydrate (gas hydrate) technology, the SF ₆ SF _6-hydrate which can be formed - as a technique for purifying made hydrate (SF ₆ -hydrate) SF ₆ gas is SF ₆ at relatively mild conditions compared to the other gases It is a technique focused on the point.

In a conventional gas hydrate is a compound in solid state the gas molecules in the low-temperature and high-pressure conditions created by forming a physical bond with the water molecule, in particular SF ₆ gas is relatively mild low temperature and high pressure _{(0 ℃, 1barG) SF 6} - Since the hydrate is formed, there is an advantage in that less energy is required than the conventional liquefaction, solidification and distillation methods. However, while the SF ₆ - is the rate of formation of hydrate is slow, and even the additive is necessary for improving the SF ₆ choice, because it uses a large amount of water, SF ₆ - need from hydrate to add a water removal step to remove the SF ₆ The disadvantage is that.

Korean Patent Publication No. 10-2017-0027068 (2017.03.09)

The serial batch type reactor equipped with a magnetic driver and a mixer in a cylindrical reactor widely used in a conventional purification apparatus by forming hydrates of waste SF ₆ gas is simple to manufacture. Hydrate formation There is a limit of the effective reaction area and hydrate accumulates in the dead zone of the reactor, which limits the movement of slurry, so that SF ₆ -hydrate cannot be obtained with good yield.

In addition, many are lost, such as SF ₆ is the serial arrangement type (serial batch type) reactor is not possible to effectively discharge the exhaust gas generated in SF ₆ purification part SF ₆ released into the air, which, because of emission of greenhouse gases into the atmosphere It will affect the environment.

In addition, purified SF ₆ alone cannot be obtained by the hydrate reactor alone, and a complete process is required, including an apparatus for separating SF ₆ from impurities and re-purifying SF ₆ from the hydrate and a water supply line for preparing a hydrate, which is an auxiliary system therefor. . In the case of SF ₆ , which is used for insulation purposes in other power projects, moisture is a deadly impurity. In the hydrate process, water is used in large quantities, so it is very important to remove water in the purified SF ₆ as much as possible.

The main impurity of the waste SF ₆ gas generated from the electricity business is air, the major component of which is nitrogen. When nitrogen and SF ₆ coexist, a hydrate of Structure II (sII) is formed. As shown in FIG. 1, the structure II hydrate is formed by combining 136 water molecules with 16 small cages and 8 large cages. The large cage will contain SF _6, which has a large molecular size, and the small cage will contain nitrogen molecules, making it impossible to completely separate SF ₆ from nitrogen using hydrates. That is, it can be seen that even SF ₆ and looking at the hydrate generation of the balance nitrogen gas mixture to create a high purity without SF ₆ in a single step the equilibrium that is shown in Figure 2 to a high purity.

In view of the foregoing, an object of the present invention is to provide an SF ₆ purification system capable of efficiently purifying a large amount of SF ₆ by improving an existing SF ₆ -hydrate purification method and an SF ₆ purification method using the same. .

SF ₆ refining system of the present invention for achieving the above object is the SF ₆ recovery system 300 for recovering the waste SF ₆ which is SF ₆ gas containing impurities in the power plant, waste in the SF ₆ recovery system 100 receiving the SF ₆ SF ₆ supplied by a mixed reactor (110) - SF ₆ produced a hydrate (SF ₆ -hydrate) and the resulting - in a dissociated hydrate (SF ₆ -hydrate) form the SF ₆ impurity is purified SF ₆ purification system 100, the exhaust gas discharge system 200 for discharging exhaust gas containing impurities generated in the waste SF ₆ purification process of the SF ₆ purification system 100 to the atmosphere, the purification in the SF ₆ purification system the SF ₆ from the water to the dryer (dryer), the water removal system 400 for removal, the recharge to recharge the SF ₆ to obtain the pressure and cooling the SF ₆ of moisture is removed through the water removal system 400 is included in the Part 600, and SF ₆ -hydrate (SF in the SF ₆ purification system 100 ₆ -hydrate) may include a water recovery system 500 for recovering the water generated by dissociation and recycle to the SF ₆ purification system.

In the SF ₆ purification system 100, the mixing reactor 110 receives waste SF ₆ from the SF ₆ recovery system 300 and receives water from a medium supply unit (not shown) to generate SF ₆ -hydrate. It consists of a hydrate formation reactor (30), and a dissociation reactor (40) for dissociating the SF ₆ -hydrate formed through the hydrate formation reactor (30) with SF ₆ and water.

The hydrate forming reactor 30 receives waste SF ₆ from the SF ₆ recovery system and receives water from a medium supply unit to continuously generate a primary SF ₆ -hydrate 10. And a ribbon type reactor 20 connected to one end of the screw reactor 10 to generate a secondary SF ₆ -hydrate from a gas exiting the screw reactor 10. .

The ribbon reactor 20 is connected to one end of the screw reactor 10, and the dissociation reactor is connected to one side of the ribbon reactor so that the primary SF ₆ -hydrate and the ribbon formed in the screw reactor 10 are connected. 2nd SF ₆ formed in the reactor 20-hydrate is formed so as to go to the dissociation reactor 40, where the first SF ₆ each of which is formed in the screw reactor 10 and the ribbon-shaped reactor 20-hydrate And the secondary SF ₆ -hydrate can be moved to the dissociation reactor by the action of gravity.

Lung SF ₆ increases the purification efficiency of the gas to form a high purity SF ₆ SF ₆ waste gas remaining in the ribbon-type reactor 20 may be moved back to the screw reactor 10 along the recovery line.

One side of the ribbon reactor 20 is provided with at least one of a sight glass and a level sensor capable of monitoring the level of reactants in the ribbon reactor, and the sight glass and the water level sensor ( Level sensor) is a discharge pipe is formed to discharge the reactant to the dissociation reactor 40 through the lower portion of the ribbon reactor in accordance with the level of the reactant in the ribbon reactor or to discharge the waste SF ₆ gas through the top.

The term "reactant" herein refers to the SF ₆ -hydrate slurry produced through waste SF ₆ and water and their hydrate reactions.

In addition, a level sensor is provided at one side of each of the ribbon reactor 20 and the dissociation reactor 40, and the reactant level in the ribbon reactor and the reactant level in the dissociation reactor are measured by the water level sensor. wherein in the ribbon-type reactor is linked to the dissociation reactor, the first SF ₆ - hydrates and the second SF ₆ - between the ribbon-type reactor 20 and the dissociation reactor 40 hydrate is to regulate the amount of movement Control valve 35 may be provided.

When the purity of the SF ₆ gas generated in the dissociation reactor is lower than the reference value, the generated SF ₆ gas is transferred to the hydrate forming reactor 30 or the SF ₆ recovery system 300 through a recovery line to return SF ₆ gas. Allow to be purified.

The SF ₆ purification system 100 may further include a buffer tank 120 temporarily storing the SF ₆ gas generated in the dissociation reactor 40.

The exhaust gas discharge system 200 recovers and analyzes the exhaust gas discharged, and if SF ₆ is included in a predetermined concentration or more, the exhaust gas is moved to the SF ₆ recovery system 300 so that the SF ₆ gas is purified again.

The water recovery system 500 is the SF ₆ SF ₆ in the purification system 100-hydrate (SF ₆ -hydrate) that dissociates the water tank to store the produced water (water tank) (510), and the water It may include a pump 520 to supply the water stored in the tank 510 back to the SF ₆ purification system 100.

The water removal system 400 may further include a buffer tank 420 temporarily storing SF ₆ gas from the dryer, and the buffer tank 420 of the water removal system 400. ) Is formed separately from the buffer tank 120 of the SF ₆ purification system 100.

The recharging unit 600 is a pressurizer 610 for pressurizing the SF ₆ gas supplied from the water removal system 400, a cooler 620 for cooling the SF ₆ gas pressurized by the pressurizer 610 to a predetermined temperature or less. ) and it may be made, including SF ₆ storage tank 630 for storing the SF ₆ out through the cooler 620.

The SF ₆ in the refill unit 600 and a pipe for charging the SF ₆ stored in the SF ₆ storage tank 630, the lower end of the SF ₆ storage tank 630 to the SF ₆ cylinder (641, 642), the upper end of the storage tank 630 has a recycling line (650) to again supply the gas on SF ₆ SF ₆ to the recovery system 300 can be connected to increase the purity of SF _6.

In addition, the SF ₆ purification method using the SF ₆ purification system of the present invention for achieving the above object, (a) SF ₆ gas containing impurities in the power plant through the SF ₆ recovery system 300 waste SF recovering the _6, (b), SF ₆ purified from the grid 100, when supplied with water from the waste SF ₆ and a medium supply portion is recovered from the SF ₆ recovery system 300 using the mixing reactor (110), SF ₆ - the hydrate to dissociate (SF ₆ -hydrate) purification step of forming the SF ₆ impurity purification, (c) tablet formed in step (b), - generating a hydrate (-hydrate SF _6), and the generated SF ₆ The SF ₆ is moved to the moisture removal system 400 to remove the moisture contained in the purified SF ₆ with a dryer (410) and (d) SF ₆ from which the moisture is removed in step (c) Navigate to the refill unit 600 to the next step of charging the SF ₆ to obtain the pressure and cooling the SF ₆ cylinder It can hamhal.

In the step (b), the waste SF ₆ gas is supplied from the SF ₆ recovery system 300 in a screw reactor 10 and water is supplied from the medium supply unit to continuously supply the first SF ₆ − Producing a hydrate, generating a secondary SF ₆ -hydrate from the gas exiting the screw reactor 10 in a ribbon type reactor 20 connected to one end of the screw reactor 10 wherein in, and dissociation reactor (dissociation reactor) (40) out through the ribbon-shaped reactor 20, the first SF ₆ - hydrates and the second SF ₆ - to include SF _6, and dissociation step of dissociating water hydrate can do.

If the purity of the purified SF ₆ gas obtained through the purification process in step (b) is less than the reference value, the purified SF ₆ gas is moved to the SF ₆ recovery system 300 and the SF ₆ purification system 100 to the ( Steps b) to (d) may be performed in sequence.

When the exhaust gas containing impurities generated during the purification process in step (b) is moved to the exhaust gas discharge system 200 to analyze the SF ₆ concentration of the exhaust gas, and it is determined that the exhaust gas contains a predetermined concentration or more SF ₆ , the exhaust gas is The step (b) to step (d) may be sequentially performed by moving to the SF ₆ recovery system 300.

In step (b), SF ₆ - water is caused by the dissociation hydrate (SF ₆ -hydrate) may include a water recovery step of recovering the water recovery system 500.

The water recovered in the water recovery step is stored in a water tank 510, and the water stored in the water tank 510 is mixed in the SF ₆ refining system 100 through a pump 520. and to supply to the lung using SF ₆ purification process it can reduce the amount of the total water purification process in SF _6.

The step (d) is to pressurize SF ₆ from which the water moved to the recharging unit 600 is removed using the pressurizer 610, and to cool the SF ₆ gas pressurized by the pressurizer 610 to the cooler 620. Cooling to a predetermined temperature using the step, storing the SF ₆ gas from the cooler 620 in the SF ₆ storage tank 630, and receives SF ₆ from the SF ₆ storage tank 630, SF ₆ And filling the cylinders 641, 642.

The (d) step, by moving the SF ₆ on the part of the gas stored in the SF ₆ storage tank 630 with SF ₆ recovery system 300 through the recycling line 650 of the SF ₆ storage tank 630 the upper end the Steps (b) to (d) may be sequentially performed.

SF ₆ is low, as well as the economic losses are growing purchase of SF ₆ need supplemental global warming is very high greenhouse gas SF ₆ will increase the recovery rate of the transfer to be released into the environment. Therefore, the effective purification of waste SF ₆ using the SF ₆ purification system of the present invention has an environmentally friendly effect of increasing the efficiency of SF ₆ purification and reducing the amount of greenhouse gases emitted into the environment.

In the SF ₆ purification system of the present invention, hydrate formation, dissociation, impurity discharge, drying, etc. are collectively performed by connecting the entire purification process into one system, thereby allowing the continuous processing of a large amount of waste SF ₆ . By improving the hydrate-forming reactor to a mixed reactor, the production and transport of hydrates was improved, and by placing the hydrate dissociation reactor under the hydrate-forming reactor, the hydrate slurry was moved to the dissociation reactor by gravity to reduce operating energy consumption. In order to reduce the operating energy consumption by installing a heat exchanger that can exchange thermal energy between processes in consideration of different operating temperatures depending on the process, and reduce the moisture content to meet the reuse criteria of the power industry by using a high-performance dryer. The water consumption was reduced by circulating and reusing the water for hydrate generation, and the purity was increased by operating several reactor sets in series when high purity SF _{6 was} required.

Therefore did not SF ₆ purification method using the gas hydrate method using a SF ₆ purification system of the present invention can not only be operated at milder conditions than the conventional SF ₆ purification methods require a separate pre-treatment benefit is very advantageous in energy terms There is this.

In addition, while the conventional SF ₆ purification method is economically suitable for high concentration SF ₆ purification of 90% or more, the SF ₆ purification method using the SF ₆ purification system of the present invention is relatively suitable for various SF ₆ concentrations (30-90%). It is also advantageous to increase the amount of SF ₆ that can be reused by refining waste SF ₆ .

Figure 1 shows the form of the hydrate crystal structure.
2 shows the phase equilibrium of a nitrogen-SF ₆ hydrate system.
3 is a schematic diagram schematically showing the configuration of the SF ₆ purification system of the present invention.
4A-4C are outline views of the SF ₆ purification system of the present invention. 4A shows a front view of the SF ₆ purification system, FIG. 4B shows a top view of the SF ₆ purification system, and FIG. 4C shows one side view of the SF ₆ purification system.
5 is a schematic flowchart of a SF ₆ purification method by the SF ₆ purification system of the present invention.
6 is a graph showing a change in pressure and SF ₆ concentration of the mixing reactor in the SF ₆ purification system according to Example 1 of the present invention.
FIG. 7 is a graph showing pressure and temperature changes of a screw reactor and a ribbon type reactor in a state where there is no supply of additional SF ₆ in an SF ₆ purification system according to Example 2 of the present invention. .

DETAILED DESCRIPTION OF THE EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Since the embodiments can be embodied in various different forms as an example, those skilled in the art to which the present invention pertains, It is not limited.

In the present invention, when a component is described as being "connected" or "coupled" to another component, the component may be directly connected to or coupled to the other component, but another component may be interposed between each component. It will be understood that it may be "connected" or "coupled".

In addition, the terms "comprise", "comprise" or "include" described in the present invention mean that the corresponding component may be inherent unless otherwise stated, and thus, other components are referred to. It should be construed as more to include other components than to exclude them.

As Figure 3, shown in Figure 4a to Figure 4c, the present invention SF ₆ purification system SF ₆ Purification system 100, the exhaust gas discharge system (200), SF ₆ recovery system 300, a moisture removal system (400 ), The water recovery system 500 and the recharge unit 600.

SF ₆ purification system 100 includes a closed-SF ₆ and SF ₆ when supplied with water - hydrate (SF ₆ -hydrate) the generated and the generated SF ₆ - to the dissociating hydrates (SF ₆ -hydrate) impurities are refined SF Forming ₆ , it comprises a mixing reactor 110 and a buffer tank (buffer tank) (120).

The mixing reactor 110 includes a screw reactor 10 and a ribbon type reactor 20 connected to one end of the screw reactor 10 to form a hydrate to generate SF ₆ -hydrate. comprises a dissociation reactor (dissociation reactor) for separating SF ₆ hydrate from 40-reactor (hydrate formation reactor) 30, and the SF ₆ formed by the hydrate formation reactor 30.

Since the hydrate forming reactor 30 is operated at a low temperature range of 0 to 5 ° C., a chiller (not shown) for cooling the reactants is configured together to maintain the required temperature.

Looking at the configuration of the mixing reactor 110 with reference to Figures 4a to 4c, the screw reactor 10 is located at the top of the mixing reactor 110, the ribbon-type reactor 20 is the screw reactor at the upper right of the screw reactor It is configured to be connected to one end of the (10), the lower side of the ribbon-type reactor 20 is configured to be connected to the dissociation reactor 40. Only the SF ₆ -hydrate slurry formed by installing a control valve 35 is selectively installed at a portion where the ribbon type reactor 20 and the dissociation reactor 40 are connected, and this configuration allows the hydrate slurry to naturally move by gravity. This is to minimize the energy required for clogging in the reactor or transfer of SF ₆ -hydrate slurry.

In addition, the ribbon type reactor 20 and the dissociation reactor 40 are provided with a level sensor (level sensor) is configured to operate the control valve 35 in conjunction with the level of the reactants of each reactor.

The SF ₆ transferred to the dissociation reactor 40 - the hydrate slurry under reduced pressure, using a principle that is raised to dissociate the SF ₆ with water it is possible to selectively separate the SF _6. At this time, in order to quickly dissociate SF ₆ -hydrate, the temperature inside the dissociation reactor 40 is increased by using a heater (not shown) outside the dissociation reactor 40.

Water dissociated with SF ₆ is configured to configure a heat exchanger to be cooled to a desired temperature and resupply to the hydrate forming reactor 30 to prevent heat loss and waste water generation.

Meanwhile, the regulator 50 and the valves 51, 52, and 53 are formed in the pipe connecting the dissociation reactor 40 and the buffer tank 120 to form SF ₆ , which is a reactant formed in the dissociation reactor 40. By measuring the pressure, the valves 51, 52, and 53 are adjusted according to the measured SF ₆ pressure so that only SF ₆ gas produced through the dissociation reactor 40 is transferred to the buffer tank 120 and stored.

The SF ₆ purified through SF ₆ refining system 100 according contains water in a saturated water vapor corresponding to the temperature and pressure dryer (dryer) * dew point (dew point) via (410)? * 62 ℃ ( 8 ppmv) followed by a series of procedures to control the moisture, pressurize it, store it in a buffer tank 420 and recharge it with a gas cylinder.

SF ₆ purification method by the SF ₆ purification system of the present invention is to recover and purify SF ₆ in a method comprising the following steps as shown in FIG.

SF ₆ purification method of the present invention, (a) recovering the waste SF ₆ which is SF ₆ gas containing impurities in the power plant through the SF ₆ recovery system 300, (b) SF ₆ purification system 100 in the recovered SF ₆ SF ₆ system using the mixing reactor (110) when supplied with water from the waste SF ₆ and a medium supply portion is recovered from the (300) the generated hydrate (-hydrate SF _6), and the resulting SF ₆ - Purifying step of dissociating hydrate (SF ₆ -hydrate) to form SF ₆ purified impurities, (c) Purified SF ₆ formed in the step (b) to the water removal system 400 purified SF ₆ Drying step of removing the water contained in the dryer (dryer) (410) and (d) SF ₆ from which the water is removed in the step (c) is moved to the recharging unit 600, and then pressurized and cooled to refine the SF Charging ₆ to the SF ₆ cylinders 641 and 642.

SF ₆ purification system of the SF ₆ Purification system 100 is SF ₆ gas mixed reactor 110, gas supply unit and the water tank 510 to supply the necessary water to hydrate formation to be supplied to include the from the gas cylinder and a hydrate It is configured to be connected to the SF ₆ recovery system 300 consisting of a medium supply unit for storing or replenishing the cooled medium by receiving the cooling water from the chiller (chiller) that can be cooled to the temperature required for the reaction 0 ~ 10 ℃.

The gas supply unit includes a regulator, a heat exchanger, and a mass flow controller (MFC), and the medium supply unit includes a water tank, a pump, and a coolant inlet / outlet port.

SF ₆ purification system 100 is a screw reactor (10) and a screw reactor (10) for continuously producing hydrates by receiving the water and SF ₆ cooled from the gas supply unit and the medium supply unit of the SF ₆ recovery system 300 Further hydrate formation with a ribbon-type reactor 20 that separates gas bubbles in the form of gas pockets in the primary SF ₆ -hydrate produced in the process and forms the hydrates with higher density. To increase the production of SF ₆ -hydrate.

In the dissociation reactor 40 supplied with the SF ₆ -hydrate generated from the screw reactor 10 and the ribbon reactor 20, the dissociation reaction of the SF ₆ -hydrate was promoted to reduce the pressure to the water and the SF ₆ gas. Play it. At this time, the water is resupplied to the water tank 510 by using a pump, and the produced SF ₆ is moved to a dryer 410 of a water removal system through a knockout drum.

The dryer 410 is composed of two bed absorption towers composed of adsorbents capable of removing moisture such as molecular sieves and zeolites, and an electric heater capable of raising the temperature inside the bed is provided. It consists of a continuous cycle of run-regeneration.

Dryer of non-purge type is used to prevent external discharge of SF ₆ during regeneration of dryer adsorbent. In addition, SF ₆ controlled moisture in the dryer includes a SF ₆ storage tank 630 for boosting the pressurizer installed in the rear stage to send SF ₆ to the gas cylinder. In this case, as the temperature of SF ₆ increases when the pressure is increased by a pressurizer, a chiller and a chiller may be further configured to lower the temperature.

Specific SF ₆ purification method using the SF ₆ purification system of the present invention described above will be described in detail with reference to Examples 1 and 2.

Example 1

The SF ₆ hydrate slurry made in the hydrate formation reactor 30 of the SF ₆ purification system of the present invention was carried out in semi-continuous type while being transferred to the dissociation reactor 40. At this time, the pressure of the screw reactor 10 and the ribbon reactor 20, the hydrate forming reactor is 6 to 9 barG, the temperature is maintained at 2 to 4 ℃ to maintain the conditions that SF ₆ -hydrate formation is better than the phase equilibrium conditions In the dissociation reaction, a temperature of 2 to 5 barG and 10 ° C. was maintained. When driving a mixing reactor 110. In this operating condition, SF ₆ in the hydrate formation reactor 30-hydrate is generated, and the generated hydrates are dissociated in the dissociation reactor 40 can be seen that to produce a refined SF ₆ have.

The operation result of the mixing reactor 110 of the SF ₆ purification system performed semi-continuously is shown in FIG. 6. As shown in FIG. 6, it can be seen that the pressure of the hydrate-forming reactor 30 increases as water for hydrate formation is continuously injected into the hydrate-forming reactor 30. Since the formed hydrate is transferred to the dissociation reactor 40, it can be seen that the pressure of the hydrate formation reactor 30 is rapidly lowered and the pressure of the dissociation reactor 40 is rapidly increased. At this time, in the dissociation reactor 40, as SF ₆ is dissociated, the water and SF ₆ are separated, and the separated water is supplied to the hydrate forming reactor 30 again to gradually decrease the pressure of the dissociation reactor 40. It can be seen that the purified SF ₆ is produced in the dissociation reactor 40 as the pressure at the lowest pressure point in the dissociation reactor 40 is gradually increased through the series of cycles. SF ₆ produced at this time was measured at a wet flow meter (wet flow meter) was measured at a level of 2.5 L per minute. The produced SF ₆ concentration was analyzed by a portable analyzer. The SF ₆ concentration before purification was 80 vol%, and the SF ₆ concentration after purification was 90 vol%. At this time, a hydrate formation-dissociation cycle may be further introduced for high purity of the SF ₆ gas produced after dissociation of the hydrate slurry.

Example 2

The application of SF ₆ separation and purification techniques using hydrate formation principles can serve two purposes. One may aim to increase the purity of SF ₆ and the other may aim to maximize the recovery of SF ₆ . As a method for maximizing the recovery rate of SF ₆ , there is a method of forming a hydrate slurry in a batch type.

In Example 2, SF ₆ to increase the recovery rate of SF ₆ to the up-then with 9 barG level to the screw reactor 10 for hydrate formation injecting the waste SF ₆ gas, and the temperature was maintained at 1 to 2 ℃ lung SF ₆ An experiment was performed to form SF ₆ -hydrate without further injection of.

FIG. 7 shows the pressure and temperature changes of the screw reactor 10 and the ribbon reactor 20 in the absence of an additional SF ₆ supply to the hydrate forming reactor 30. As the hydrate is formed, the screw reactor 10 ) And the pressure of the ribbon reactor 20 can be seen to be sharply lowered, and in the section where the pressure is sharply lowered, the temperature can be seen to rise slightly. This is a change in temperature observed with the exothermic reaction of the hydrate formation reaction.

The formation of the SF ₆ -hydrate can be confirmed directly through the visible window of the ribbon reactor 20 or indirectly through pressure changes and temperature changes in the screw reactor 10 and the ribbon reactor 20. The formed hydrate slurry may be transferred to the dissociation reactor 40 for dissociation to produce purified SF ₆ by forming hydrate dissociation conditions while maintaining at 2-5 barG, 10 ° C. level. At this time, the concentration of the produced SF ₆ can be purified to 90% level when injected into the hydrate-forming reactor 30 of the waste SF ₆ level of 80%. When supplied in this process to add water when boost than the recovery rate of SF ₆ is the pressure of the hydrate formation reactor 30 to stabilize in order to minimize the amount of SF ₆ is discharged to the atmosphere, the pressure in the reactor while the increase of the SF ₆ Additional methods can be used to maximize recovery and minimize emissions of SF ₆ .

10 screw reactor 20 ribbon reactor
30 hydrate forming reactor 35 control valve
40: dissociation reactor 50: regulator
51, 52, 53: valve 100: SF ₆ purification system
110: mixing reactor 120: buffer tank
200: exhaust gas discharge system 300: SF ₆ recovery system
310, 320: waste SF ₆ reservoir 330: mixing tank
400: water removal system 410: dryer
420: buffer tank 500: water recovery system
501, 502: valve 510: water tank
520: pump 600: rechargeable part
610: pressurizer 620: cooler
630: SF ₆ storage tank 641, 642: SF ₆ cylinder
650 recirculation piping

Claims (23)

An SF ₆ recovery system for recovering waste SF ₆ , which is an SF ₆ gas containing impurities in a power plant;
The hydrate to dissociate (SF ₆ -hydrate) impurity is purified, said SF ₆ when supplied the waste SF ₆ SF ₆ in the recovery system using a mixed reactor produce a hydrate (-hydrate SF _6), and the generated SF ₆ SF ₆ purification system to form SF ₆ ;
An exhaust gas discharge system for discharging exhaust gas containing impurities generated in the waste SF ₆ purification process of the SF ₆ purification system to the atmosphere;
The SF ₆ removes water for removing moisture included in the SF ₆ purified in the purification system to the dryer (dryer) system;
Recharging unit for recharging the SF ₆ to obtain the pressure and the cooling is removed SF ₆ water through the water removal system; And
SF ₆ SF ₆ in the purification system - to recover the hydrate (SF ₆ -hydrate) is dissociation of water occurs the SF ₆ Water recovery system to recycle the purified system; includes,
The mixing reactor,
A hydrate-forming reactor receiving waste SF ₆ from the SF ₆ recovery system and receiving water from a medium supply unit to generate SF ₆ -hydrate; And
SF ₆ purification system according to claim consisting of; dissociation reactor (dissociation reactor) dissociating the hydrate SF ₆ and water, wherein the SF ₆ formed by the hydrate formation reactor. The method of claim 1,
The hydrate forming reactor,
A screw reactor receiving the waste SF ₆ gas from the SF ₆ recovery system and receiving water from the medium supply unit to continuously generate the first SF ₆ -hydrate; And
SF ₆ purification system comprising: a; ribbon-shaped reactor (ribbon type reactor) to produce a hydrate-connected to one side ends of the screw reactor, the second SF ₆ from a gas from the reactor via the screw. The method of claim 2,
One end of the screw reactor is connected to the ribbon reactor,
SF characterized in that the formed hydrates to go to the dissociation reactor, - the second SF ₆ formed in the hydrate and the ribbon-shaped reactor has the ribbon-shaped reactor one side dissociation reactor is connected to the first SF ₆ formed in the screw reactor ₆ purification system. The method of claim 3,
The first SF ₆ - hydrates and the second SF ₆ - SF ₆ hydrate is purification system characterized in that the movement by the dissociation reactor by the action of gravity. The method of claim 2,
Lung SF ₆ gas remaining in the ribbon-type reactor is SF ₆ purification system, characterized in that back to back to the screw reactor along the recovery line. The method of claim 2,
One side of the ribbon reactor, SF ₆ purification system, characterized in that any one or more of the sight glass (sight glass) and a level sensor (level sensor) for monitoring the level of the reactants in the ribbon reactor. The method of claim 6,
The vision (sight glass) and the level sensor (level sensor) is SF ₆ purification system characterized in that the discharge pipe is one of the reactants of the waste SF ₆ gas in the reactor so that the ribbon-like discharge is formed. The method of claim 2,
One side of each of the ribbon-type reactor and the dissociation reactor is provided with a level sensor,
The reactant level in the ribbon reactor measured by the water level sensor and the reactant level in the dissociation reactor are linked so that the primary SF ₆ -hydrate and the secondary SF ₆ -hydrate are transferred from the ribbon reactor to the dissociation reactor. SF ₆ purification system, characterized in that a control valve between the dissociation ribbon reactor and the dissociation reactor to adjust the amount of movement. The method of claim 1,
When the purity of the SF ₆ gas generated in the dissociation reactor is less than the reference value,
The resulting SF ₆ SF ₆ gas refining system, characterized in that moving through the return line into the hydrate formation reactor or the SF ₆ recovery system. The method of claim 1,
The SF ₆ purification system
SF ₆ purification system comprising a buffer tank for temporarily storing the SF ₆ gas generated in the dissociation reactor. The method of claim 1,
The exhaust gas discharge system is SF ₆ purification system, characterized in that to recover the exhaust gas discharged to the SF ₆ recovery system, if it is determined that the exhaust gas discharged by a predetermined concentration or more SF ₆ is included. The method of claim 1,
The water recovery system is the SF ₆ SF ₆ in the purification system-hydrate (SF ₆ -hydrate) a water tank (water tank) to store the dissociated water are generated; And
SF ₆ purification system comprising a; pump to supply the water stored in the water tank back to the SF ₆ purification system. The method of claim 1,
The moisture removal system,
SF ₆ purification system, characterized in that it comprises a buffer tank (buffer tank) for temporarily storing the SF ₆ gas from the dryer. The method of claim 1,
The recharger,
A pressurizer for pressurizing the SF ₆ gas supplied from the water removal system;
A cooler cooling the SF ₆ gas pressurized by the pressurizer to a predetermined temperature or less; And
SF ₆ purification system comprising: a; SF ₆ SF ₆ from a storage tank to store through the cooler. The method of claim 14,
The lower end of the storage tank is SF ₆ and a pipe for charging the SF ₆ SF ₆ stored in the storage tank to the SF ₆ cylinder,
SF ₆ gas refining system of the SF _6, on the upper end of the SF _6, a storage tank in order to improve the purity of SF _6, characterized in that the recycling line is connected to re-supply the recovered SF ₆ system. A method for purifying SF ₆ using the SF ₆ purification system according to any one of claims 1 to 15,
(a) recovering the waste SF ₆ which is an SF ₆ gas containing impurities in the power plant through the SF ₆ recovery system;
(b) SF ₆ in the purification system when supplied with water from the waste SF ₆ and a medium supply portion is recovered from the recovery system SF ₆ SF ₆ in a mixed reactor-produced a hydrate (SF ₆ -hydrate) and the resulting SF ₆ A purification step of dissociating -hydrate (SF ₆ -hydrate) to form SF ₆ in which impurities are purified;
(c) a drying step of moving the purified SF ₆ formed in step (b) to a moisture removal system to remove moisture contained in the purified SF ₆ with a dryer; And
(d) SF ₆ from which the water is removed in step (c) is moved to the recharging unit, and then pressurized and cooled to fill the purified SF ₆ in the SF ₆ cylinder; SF ₆ purification method comprising a . The method of claim 16,
Step (b),
Receiving a waste SF ₆ gas from the SF ₆ recovery system in a screw reactor and receiving water from a medium supply unit to continuously generate a primary SF ₆ -hydrate;
Generating a secondary SF ₆ -hydrate from a gas exiting the screw reactor in a ribbon type reactor connected to one end of the screw reactor; And
The out via the ribbon-type reactor in the dissociation reactor (dissociation reactor) the first SF ₆ - hydrates and the second SF ₆ - a hydrate SF ₆ and dissociation step of dissociating water; SF _6, characterized in that it comprises a Purification method. The method of claim 17,
If the purity of the purified SF ₆ gas from the purification step in step (b) is less than the reference value,
The purified SF ₆ gas is moved to the SF ₆ recovery system and SF ₆ purification system to perform the steps (b) to (d) step SF ₆ purification method. The method of claim 16,
When the exhaust gas containing impurities generated during the purification process in step (b) is moved to the exhaust gas discharge system and the SF ₆ concentration of the exhaust gas is analyzed to determine that the exhaust gas contains SF ₆ or above a predetermined concentration,
SF ₆ purification method characterized in that the step (b) to step (d) is carried out in sequence by moving the exhaust gas to the SF ₆ recovery system. The method of claim 16,
SF ₆ refining method comprising the; water caused a hydrate (SF ₆ -hydrate) dissociates the water recovered by the water recovery system recovering - SF ₆ in the step (b). The method of claim 20,
The water recovered in the water recovery step is stored in a water tank (water tank), SF ₆ purification method characterized in that the water stored in the water tank is supplied to the SF ₆ purification system through a pump. The method of claim 16,
In step (d),
Pressurizing SF ₆ from which the moisture transferred to the recharging unit is removed using a subscriber;
Cooling the SF ₆ gas pressurized by the pressurizer to a predetermined temperature using a cooler;
And storing the SF ₆ from SF ₆ through the cooler to the storage tank; And
SF ₆ refining method comprising the; receive SF ₆ SF ₆ supplied from the storage tank further comprising: charging the SF ₆ cylinder. The method of claim 22,
Wherein (d) In the step, the SF ₆ storage tank some gas step (b) to the step (d) the SF ₆ by moving the SF ₆ recovery system through the SF ₆ stores recycling line of the tank upper part on the stored in SF ₆ purification method, characterized in that carried out in sequence.

Images