JP2006116503A - Concentrator of low-concentration gas-hydrate slurry and gas-hydrate production plant - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To concentrate a low-concentration gas-hydrate slurry exhausted from a spray type gas-hydrate producer, with a simple constituent. <P>SOLUTION: A concentrator 2 comprises an inlet pipe 30 of a large diameter to which a gas-hydrate slurry is supplied, an outlet pipe 31 of a small diameter from which the gas-hydrate slurry is exhausted, a filter wall 32 connecting the inlet pipe and the outlet pipe and consisting of a porous material formed in a conical cylindrical shape, a separated-water receiving part 33 formed so as to surround the outer periphery of the filter wall, and a water draining nozzle 34 arranged at the separated-water receiving part. The low-concentration gas-hydrate slurry is concentrated by the concentrator 2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a concentrator for a low concentration gas hydrate slurry and a gas hydrate production plant using the same.

  Gas hydrate is a solid hydrate that has a structure in which gas is taken into a cage made of water molecules, and is stable under atmospheric pressure of -10 ° C., so it is a natural alternative to liquefied natural gas (LNG). Research is being carried out to use it as a means of transporting and storing gas.

  In general, the gas hydrate is generated, for example, by reacting a raw material gas such as natural gas, methane gas, and carbon dioxide gas with water in a low-temperature and high-pressure generation vessel. Since the gas hydrate produced in the production vessel contains a large amount of unreacted water, it is necessary to separate the water and purify the product gas hydrate.

  According to the method for producing a gas hydrate described in Patent Document 1, a raw material gas is supplied into a production vessel, and low-temperature circulating water is sprayed (sprayed) into the raw material gas in the production vessel. A so-called spray-type gas hydrate generator is used. In such a gas hydrate generator, the gas hydrate floating in the vicinity of the liquid level in the production vessel is extracted as a slurry together with water and led to a double-structure screw press type dehydrator having a meshed inner cylinder. Physically dehydrated. Since this screw press type dehydrator has a limited dehydration rate, the screw press type dehydrator is further led to a twin-screw type dehydrator and dehydrated by a hydration reaction in which the adhering water of gas hydrate reacts with the raw material gas. We try to get less product gas hydrate. Patent Document 2 also describes dehydration by a similar process.

JP 2003-55675 A JP 2003-64385 A

  By the way, the gas hydrate slurry extracted from the spray-type generators described in Patent Documents 1 and 2 generally has a low gas hydrate concentration (for example, 0.5 to 5% by weight). For example, if the concentration of the gas hydrate slurry extracted from the generator is too low, it is difficult to dehydrate to a sufficient gas hydrate concentration (for example, about 50 to 70% by weight) in a screw press type dehydrator. There is. Thus, when the dehydration rate in the screw press type dehydrator is too low, the hydration reaction in the subsequent hydration dehydration step is not sufficiently performed, and the concentration of the product gas hydrate cannot be sufficiently increased.

  Thus, when trying to obtain a product gas hydrate having a sufficient concentration, the residence time in the spray-type gas hydrate generator is increased to increase the slurry concentration, or in a physical dehydration apparatus such as a screw press type dehydration apparatus. In order to increase the dehydration rate, the apparatus must be enlarged.

  An object of the present invention is to concentrate a low concentration gas hydrate slurry discharged from a spray-type gas hydrate generator or the like with a simple configuration, so that a gas hydrate having a desired concentration or more can be obtained without increasing the size of the apparatus. There is to get.

  In order to solve the above problems, the present invention connects a large-diameter inlet pipe to which a gas hydrate slurry is supplied, a small-diameter outlet pipe from which the gas hydrate slurry is discharged, and connects the inlet pipe and the outlet pipe. Comprising a filter wall made of a porous material formed in a conical cylinder shape, a separation water reservoir part surrounding the outer periphery of the filter wall, and a drain nozzle provided in the separation water reservoir part The concentrated gas hydrate slurry is concentrated by the concentrator formed.

  In other words, the water in the gas hydrate slurry permeates the filter wall by inserting the concentrator of the present invention in the middle of the transfer pipe of the gas hydrate slurry transferred from the spray type gas hydrate generator to the physical dehydrator. Then, it is selectively separated into the separated water reservoir. Here, since the amount of separated water correlates with the pore size and area of the filter wall, the slurry flow rate, etc., the gas hydrate slurry concentration is concentrated to the inlet concentration required by the physical dehydrator by appropriately setting them. be able to.

  In this case, since there is a risk of gas hydrate clogging in the pores of the filter wall, an ultrasonic vibration device for irradiating ultrasonic waves to the porous portion of the filter wall is provided, and the gas hydrate clogged by ultrasonic vibration is provided. Peeling is preferable.

  Further, instead of ultrasonic vibration, a swirl flow forming means, for example, swirl blades called a static mixer or an in-line mixer can be provided in the inlet pipe of the concentrator. According to this, a swirling flow of gas hydrate slurry is formed in the concentrator, and the gas hydrate concentration in the filter wall portion is lower than the central portion due to the centrifugal force of the swirling flow, so that clogging can be suppressed. it can.

  Furthermore, as a method for eliminating clogging of the filter wall hole, a backwashing means for flushing the gas hydrate clogged in the hole by spraying pulsed backwash water onto the outer surface of the filter wall of the separation water reservoir is provided. Can do.

  In addition, a gas hydrate production plant using the concentrator of the present invention includes a generator for producing a slurry containing gas hydrate by hydrating a raw material gas and water, and extracting water at the bottom of the generator. A water circulation pump for spraying into the generator from a spray nozzle at the top of the generator through a cooler, a slurry transfer pump for extracting a slurry containing gas hydrate from the middle part of the generator, and the slurry transfer pump A concentrator for separating and concentrating the water from the gas hydrate slurry supplied, and a physical dehydrator for physically dehydrating the gas hydrate slurry concentrated by the concentrator, A large-diameter inlet pipe connected to piping connected to the discharge of the slurry transfer pump, and a small-diameter outlet connected to piping connected to the inlet of the physical dehydrator A filter wall made of a porous material formed in a conical cylinder shape connecting the inlet pipe and the outlet pipe, a separation water reservoir portion surrounding the outer periphery of the filter wall, and a separation water reservoir portion A drainage nozzle provided can be provided.

  According to the present invention, a low concentration gas hydrate slurry discharged from a spray-type gas hydrate generator or the like can be concentrated with a simple configuration, and a gas hydrate having a desired concentration or more can be obtained without increasing the size of the apparatus. Can be obtained.

Hereinafter, embodiments of the present invention will be described.
(Embodiment 1)
FIG. 1 shows a configuration diagram of an embodiment of a concentrator for low-concentration gas hydrate slurry of the present invention, and FIG. 2 shows a configuration diagram of a gas hydrate manufacturing plant of an embodiment to which the present invention is applied.

  The embodiment shown in FIG. 2 shows a plant for producing a gas hydrate of natural gas (hereinafter abbreviated as NGH). However, the present invention is not limited to natural gas, and is a gas hydrate production of other raw material gases. Applicable to. As shown in the figure, the gas hydrate manufacturing plant of the present embodiment concentrates the gas hydrate slurry manufacturing apparatus including the generator 1 that generates the NGH slurry, and the low-concentration NGH slurry generated by the generator 1. The condensing device 2, the physical dehydrating device 3 that physically dehydrates the water of the NGH slurry concentrated by the concentrating device 2, and the NGH adhering water dehydrated by the physical dehydrating device 3 and the natural gas. And a hydration dehydration device 4 that raises the concentration of NGH to the product level. The generator 1, the concentrator 2, the physical dehydration device 3, and the hydration dehydration device 4 are all maintained at a predetermined high pressure (for example, 3 to 10 MPa) and low temperature (for example, 1 to 5 ° C.).

  The generator 1 is formed of a cylindrical container, and natural gas, which is a raw material gas cooled from an NG (natural gas) tank 11 through a compressor 12 and a cooler 13, is continuously supplied to the upper part of the container. It has become so. Further, the water cooled from the water tank 14 via the pump 15 and the cooler 16 is continuously supplied to the bottom of the generator 1. In the coolers 13 and 16, refrigerant is circulated from a refrigeration apparatus (not shown), whereby natural gas and water supplied to the generator 1 are cooled to a predetermined temperature. A water spray nozzle 17 is provided at the top of the generator 1, and water extracted by a water circulation pump 18 communicated with the bottom of the generator 1 is cooled by a cooler 19 at the spray nozzle 17. It is designed to be circulated. In the cooler 19, a refrigerant is circulated from a refrigeration apparatus (not shown), thereby cooling water supplied to the spray nozzle 17 to a predetermined temperature (for example, 1 ° C.).

  The NGH slurry generated in the generator 1 is continuously extracted from the middle part of the generator 1 by the slurry transfer pump 20 and supplied to the concentrator 2, where a part of the water is separated to obtain the NGH slurry. It comes to concentrate. The NGH slurry concentrated by the concentrator 2 is supplied to the physical dehydrator 3 and dehydrated by physical squeezing. As the physical dehydrator 3, for example, a screw press type dehydrator described in Patent Document 1 can be applied. That is, it is formed by storing the meshed inner cylinder in the outer cylinder, inserting a rotating shaft having screw blades into the inner cylinder, and gradually narrowing the gap between the rotating shaft and the inner cylinder in the screw transfer direction. ing. The water separated from NGH by the concentrator 2 and the physical dehydrator 3 is returned to the generator 1 by the pump 21.

  On the other hand, the NGH dehydrated by the physical dehydration device 3 is supplied to the hydration dehydration device 4, and NGH is generated by reacting the adhering water adhering to the NGH and the separately supplied source gas, thereby producing NGH. The concentration is sufficiently increased. As the hydration dehydrator 4, for example, a twin-screw type dehydrator described in Patent Document 1 can be applied. Alternatively, a fluidized bed type hydration dehydration apparatus can be applied. That is, the fluidized bed type hydration dehydrator supplies NGH dehydrated by the physical dehydrator 3 into a vertical container, blows a raw material gas from the bottom of the container to form a fluidized bed of NGH, and performs a fluidized bed reaction. NGH is used to convert adhering water adhering to NGH.

  Next, operation | movement of the gas hydrate manufacturing plant of this embodiment is demonstrated. As described above, the generator 1 is maintained at a high pressure (for example, 3 to 10 MPa) by the supply pressure of natural gas and water, and is maintained at a low temperature (for example, 1 to 5 ° C.) by the coolers 13 and 16. Yes. Then, when sufficiently cooled water is sprayed from the top spray nozzle 17 into the generator 1, it reacts with the natural gas in the gas phase in the generator 1, and the hydrated product NGH powder Granules 22 are generated and fall into the liquid phase part. Water containing NGH in the liquid phase part is extracted from the bottom by the water circulation pump 18 and sprayed again from the spray nozzle 17 into the generator 1 through the cooler 19. Note that a filter 23 made of a porous plate or the like is provided at the bottom of the generator 1 in order to prevent NGH from being mixed into the water extracted by the water circulation pump 18. Further, since the NGH generation reaction in the generator 1 is accompanied by heat generation, in order to maintain the temperature in the generator 1 at the set temperature, the cooler 19 cools and sprays the circulating water to near the limit temperature for freezing. It circulates to the nozzle 17.

  In this way, NGH is continuously generated by circulating and spraying water. Since the specific gravity of the generated NGH is smaller than that of water, the NGH concentration in the vicinity of the water surface in the liquid phase portion is the highest. Therefore, NGH near the water surface of the liquid phase part is extracted as slurry by the slurry transfer pump 20. The concentration of the extracted NGH slurry is generally a low concentration (for example, 0.5 to 5% by weight).

  Here, the detailed structure of one Embodiment of the concentrator 2 which concerns on the characteristic of this invention is demonstrated with reference to FIG. As shown in FIG. 1, the concentrator 2 includes a large-diameter inlet pipe 30 connected to the discharge pipe of the slurry transfer pump 20, a small-diameter outlet pipe 31 connected to the inlet pipe of the physical dehydrator 3, and these And a separation water reservoir 33 formed so as to surround the outer periphery of the filter wall 32. The filter wall 32 is formed by processing a plate material having a large number of holes (for example, a diameter of 0.1 to 1.0 mm) such as a wire mesh into a truncated conical cylinder shape. Further, the separation water reservoir 33 is provided with a drain nozzle 34, and the drain nozzle 34 is connected to the suction side of the pump 21 via a flow control valve 35. Further, an ultrasonic vibration device 36 is attached to the outer periphery of the separated water reservoir 33. Further, a mass meter 37 for measuring the mass of the NGH slurry flowing out from the outlet pipe 31 is provided, the concentration of the NGH slurry is obtained based on the mass measured by the mass meter 37, and the concentration of the discharged NGH slurry is set to a set value. The amount of water to be discharged is controlled by controlling the flow rate control valve 35 so that the water is discharged.

  Since it is formed in this way, when a low concentration (for example, 0.5 to 5% by weight) of NGH slurry is supplied to the inlet pipe 30 of the concentrator 2 of the present embodiment, a part of moisture in the slurry. Selectively flows into the separation water reservoir 33 through the hole of the filter wall 32. Thereby, the NGH concentration of the NGH slurry flowing through the concentrator 2 is concentrated, and the concentrated medium concentration (for example, 10 to 30 wt%) NGH slurry can be supplied to the physical dehydrator 3. The concentration of the NGH slurry in the concentrator 2 can be adjusted by appropriately setting the diameter of the filter wall 32 (that is, the flow rate of the NGH slurry) and the axial length.

  By the way, since the NGH powder particles adhere to the inner surface of the filter wall 32 and are clogged, the ultrasonic vibration device 36 provided on the outer periphery of the separation water reservoir 33 is continuously or intermittently driven, Ultrasonic vibration is applied to the granular particles of NGH clogged in the filter wall 32 to separate them. Thereby, the performance of the concentrator 2 can be exhibited continuously. In the present embodiment, the example in which the ultrasonic vibration device 36 is provided on the outer periphery of the separation water reservoir 33 has been shown. However, the present invention is not limited to this, and a large number of ultrasonic transducers are placed close to the outer surface of the filter wall 32. Alternatively, they can be dispersed by being brought into contact with each other.

  In the present embodiment, the NGH slurry concentration discharged from the concentrator 2 is held at a set value by controlling the flow rate control valve 35 based on the NGH concentration measured by the mass meter 37. When it is not necessary to control the concentration of NGH slurry supplied to the physical dehydrator 3 with high accuracy, the control system using the flow rate control valve 35 and the mass meter 37 can be omitted. In that case, it is preferable to use a flow rate adjustable valve instead of the flow rate control valve 35 so as to adjust the flow rate within a certain range.

  Moreover, in this embodiment, although the example which applies ultrasonic vibration to the granular material of NGH clogged with the filter wall 32 and made it peel is shown, it replaces with this and backwash water is given to the outer surface of the filter wall 32. You may provide the backwashing means ejected in pulses.

As described above, according to this embodiment, the low-concentration gas hydrate slurry discharged from the spray-type gas hydrate generator can be concentrated with a concentrator having a simple configuration. Therefore, the generator 1 and the physical dehydrator 3 can be concentrated to a gas hydrate slurry having a concentration suitable for the inlet concentration of the physical dehydrator 3 without increasing the size, and a sufficient dehydration rate of the physical dehydrator 3 can be secured. . As a result, the dehydration process in the hydration dehydrator 4 can be performed effectively, and a product gas hydrate having a desired concentration can be obtained.
(Embodiment 2)
FIG. 3 shows a configuration diagram of another embodiment of the concentrator for the low concentration gas hydrate slurry of the present invention. The present embodiment differs from the embodiment of FIG. 1 in that, instead of the ultrasonic vibration device 36, a static mixer or a mixer is provided in the inlet pipe 30 portion of the concentrator 2 in order to suppress clogging of the filter wall 32. A swirl flow forming means 38 called an inline mixer is provided. That is, the swirl flow forming means 38 is formed by supporting a blade member 38a in which a strip-shaped plate material is formed like a screw blade on a tube wall by a support member 38b.

By forming in this way, according to this embodiment, the flow of the NGH slurry flowing into the inlet pipe 30 is converted into a swirl flow by the blade member 38a, and water having a specific gravity larger than that of NGH enters the filter wall 32 side. As a result, the proportion of NGH flowing through the center side of the filter wall 32 increases. As a result, the NGH concentration in the axial center portion of the concentrator 2 is increased and the NGH concentration in the peripheral portion on the filter wall 32 side is decreased, so that clogging of the filter wall 32 due to NGH can be reduced.
(Embodiment 3)
FIG. 4 shows a configuration diagram of another embodiment of the concentrator for low concentration gas hydrate slurry of the present invention. 3 differs from the embodiment of FIG. 3 in that a plurality of swirls are formed on the inner wall of the inlet pipe 30 instead of the swirl flow forming means 38 of the blade member 38a in which a strip-shaped plate material is formed like a screw blade. The swirl flow forming means 38 composed of the blades 40 is provided. Other portions are denoted by the same reference numerals as those in FIG. FIG. 5B is a cross-sectional view taken along line IVB-IVB in the perspective view of FIG.

  As shown in the drawing, a plurality (eight in the illustrated example) of swirl vanes 40 are provided to stand radially from the inner wall of the pipe toward the center of the pipe and are inclined with respect to the flow path direction. As a result, the NGH slurry flowing in from the inlet pipe 30 is given a rotational component by the plurality of swirl vanes 40, and a spiral flow is formed. Here, since the specific gravity of NGH is smaller than that of water, the NGH collects and flows in the central portion of the pipe, and the water flows along the filter wall 32 formed of a wire mesh or the like and is transmitted to the separated water reservoir 33.

  Here, the swirl vane 40 is inclined by 2 to 30 °, preferably 5 to 10 ° with respect to the flow path direction. Further, the cross section of the swirl vane 40 is preferably formed in a symmetric streamline shape, but may be asymmetrical in the left-right direction. Moreover, in order to generate an effective spiral flow in the NGH slurry, the height of the swirl vane 40 is preferably 0.1 to 0.5 times the inner diameter of the inlet pipe 30.

It is a block diagram of one Embodiment of the concentrator of the low concentration gas hydrate slurry of this invention. It is a block diagram of the gas hydrate manufacturing plant of one Embodiment to which the concentrator of the low concentration gas hydrate slurry of this invention is applied. It is a block diagram of other embodiment of the concentrator of the low concentration gas hydrate slurry of this invention. It is a block diagram of further another embodiment of the concentrator of the low concentration gas hydrate slurry of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Generator 2 Concentrator 3 Physical dehydration device 4 Hydration dehydration device 17 Spray nozzle 18 Water circulation pump 19 Cooler 20 Slurry transfer pump 21 Pump 32 Filter wall 33 Separation water reservoir 35 Flow rate control valve 36 Ultrasonic vibration device 37 Mass meter 38 Swirl flow forming means

Claims (5)

  From a large-diameter inlet pipe to which gas hydrate slurry is supplied, a small-diameter outlet pipe from which the gas hydrate slurry is discharged, and a porous material formed in a conical cylinder shape connecting the inlet pipe and the outlet pipe Concentration of low-concentration gas hydrate slurry comprising a filter wall, a separation water reservoir formed surrounding the outer periphery of the filter wall, and a drain nozzle provided in the separation water reservoir vessel.   The concentrator for low-concentration gas hydrate slurry according to claim 1, wherein an ultrasonic vibration device for irradiating ultrasonic waves to the porous portion of the filter wall is provided.   2. The concentrator for low-concentration gas hydrate slurry according to claim 1, wherein swirl flow forming means is provided in the inlet pipe.   The concentrator for low-concentration gas hydrate slurry according to claim 1, further comprising backwashing means for injecting pulsed backwash water on an outer surface of the filter wall of the separated water reservoir. A generator for producing a slurry containing gas hydrate by hydration reaction of raw material gas and water, and water from the bottom of the generator is withdrawn from the spray nozzle to the top of the generator through a cooler. A water circulation pump sprayed into the slurry, a slurry transfer pump for extracting a slurry containing gas hydrate from the middle part of the generator, and a concentration for separating and concentrating the moisture of the gas hydrate slurry supplied from the slurry transfer pump And a physical dehydration device for physically dehydrating the gas hydrate slurry concentrated by the concentrator,
The concentrator includes a large-diameter inlet pipe connected to a pipe communicated with the discharge of the slurry transfer pump, a small-diameter outlet pipe connected to a pipe communicated with an inlet of the physical dehydrator, and the inlet A filter wall made of a porous material formed in the shape of a conical cylinder connecting the pipe and the outlet pipe, a separation water reservoir formed surrounding the outer periphery of the filter wall, and drainage provided in the separation water reservoir A gas hydrate manufacturing plant comprising a nozzle.

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