JP4917817B2 - Gas hydrate slurry production equipment - Google Patents

Description

  The present invention relates to a gas hydrate slurry production apparatus.

  The gas hydrate is a solid hydrate having a structure in which gas is taken into a tub formed by water molecules, and is stable at atmospheric pressure of −10 ° C., for example, to liquefied natural gas (LNG). Research is underway to use it as a means of transporting and storing alternative natural gas.

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

  In Patent Document 1, gas hydrate and water are extracted from a production container as a slurry, dehydrated with a physical dehydrator, and the concentration of the gas hydrate slurry introduced into the physical dehydrator is detected. Accordingly, it is described that the amount of dehydration in the physical dehydrator is controlled accordingly. According to this, the concentration of the gas hydrate after physical dehydration can be made constant.

JP 2003-64385 A

  However, Patent Document 1 describes that the concentration of the gas hydrate slurry introduced into the physical dehydrator is detected using the difference in dielectric constant between the gas hydrate and water. No consideration is given to the control of the concentration of the gas hydrate slurry introduced into the slag. Therefore, if the concentration of the gas hydrate slurry becomes too high, it becomes difficult to transfer the gas hydrate slurry from the production vessel to the physical dehydrator due to the deterioration of the fluidity of the gas hydrate slurry.

  An object of the present invention is to stably transfer a hydrate slurry generated by a generator to a dehydrator.

In order to solve the above-mentioned problems, a gas hydrate slurry manufacturing apparatus of the present invention includes a generator for generating a slurry containing gas hydrate by hydration reaction of continuously supplied raw material gas and water, and a generator A gas circulation system for extracting the raw material gas from the top of the gas generator and diffusing the raw material gas from the bottom of the generator to circulate the raw material gas , and extracting the slurry containing the gas hydrate from the bottom of the generator , a slurry circulating system for circulating through the cooler for cooling, the slurry transfer pump for transferring the dewatering device from the bottom of the generator by extracting a slurry containing gas hydrate, the gas in the slurry withdrawn from the bottom of the generator flow control for controlling the slurry concentration detector for detecting on the basis of hydrate concentration to the conductivity, the circulating gas of the raw material gas to be circulated is provided in the gas circulation system When a flow control valve for controlling the circulation slurry of the slurry being circulated is provided in the slurry circulating system, by controlling at least one of the means for controlling the refrigerant flow rate of the cooler, is detected by a slurry concentration detector And a control means for controlling the gas hydrate concentration in the slurry within a set range.

  That is, if the circulation amount of the raw material gas diffused in the slurry in the generator is increased, the hydration reaction is promoted, so that the gas hydrate concentration in the slurry can be controlled. The hydration reaction is exothermic and the hydration reaction depends on the degree of supercooling (difference between the equilibrium temperature of gas hydrate formation and the temperature in the generator), so the slurry temperature in the generator is controlled. By doing so, the gas hydrate concentration in the slurry can be controlled. As a method for controlling the slurry temperature in the generator, a method for controlling the circulation amount of the slurry circulated through the cooler and a method for controlling the temperature by controlling the refrigerant flow rate of the cooler are considered.

  On the other hand, the concentration of the slurry containing gas hydrate extracted from the bottom of the generator can be determined by, for example, providing a pair of electrodes in the slurry and applying a predetermined voltage between these electrodes to conduct the slurry. It can be detected by determining the rate. That is, there is a correlation between the slurry concentration and the conductivity of the slurry, and the slurry concentration can be detected from the conductivity of the slurry based on the correlation.

  In view of these, the present invention controls at least one of the amount of circulating gas, the amount of circulating slurry, and the temperature of the circulating slurry so that the concentration of the slurry extracted from the bottom of the generator falls within a set range. Therefore, the gas hydrate concentration in the slurry can be accurately controlled to a desired value. The hydration reaction can be promoted by stirring the slurry in the generator.

  Thus, according to the gas hydrate slurry production apparatus of the present invention, the concentration of the gas hydrate slurry to be produced can be controlled accurately and continuously, so that the hydrate slurry produced by the generator can be dehydrated. Can be transported stably.

  In this case, the concentration detection of the hydrate slurry may be performed on the gas hydrate slurry upstream of the slurry transfer pump, or may be performed on the gas hydrate slurry circulated by the slurry circulation device. .

  ADVANTAGE OF THE INVENTION According to this invention, the hydrate slurry produced | generated with the generator can be stably transferred to a dehydrator.

  Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, the gas hydrate slurry manufacturing apparatus of this invention is shown. Although the present embodiment shows an apparatus for producing a natural gas hydrate (hereinafter abbreviated as NGH) slurry, the present invention is not limited to natural gas and is applicable to the production of hydrate slurries of other raw material gases. it can.

  As shown in FIG. 1, the gas hydrate slurry manufacturing apparatus 1 of the present embodiment is provided at a generator 2 that generates NGH slurry, a stirrer 3 that stirs the inside of the generator 2, and a lower portion of the generator 2. The nozzle 4 is configured.

  The generator 2 is formed of a cylindrical container, and is supplied with a certain amount of high-pressure raw material gas (natural gas) and high-pressure water from a supply device (not shown), and the natural gas introduced into the generator 2 Water reacts under conditions of low temperature (for example, 1 to 10 ° C.) to produce NGH. In order to promote the NGH production reaction, the water in the generator 2 is agitated by the agitator 3 and the natural gas at the top of the generator 2 is extracted by the circulating gas blower 5 and produced from the nozzle 4 at the bottom of the generator 2. A gas circulation system that diffuses into the water of the vessel 2 is provided. The amount of circulating gas is controlled by a flow control valve 7 equipped with a gas flow meter. Further, since NGH generation is accompanied by heat generation, in order to maintain the temperature in the generator 2 at the set temperature, the NGH slurry containing NGH generated from the bottom of the generator 2 is extracted by the circulating slurry pump 8 and cooled. 9 is provided with a slurry circulation system that is cooled by the refrigerant and returned to the upper part of the generator 2. The slurry circulation rate is controlled by a flow rate control valve 10 equipped with a slurry flow meter.

  The NGH slurry generated in the generator 2 in this way is continuously extracted from the bottom of the generator 2 by the slurry transfer pump 12 and supplied to the dehydrator. Note that the generator 2, the gas circulation system, the slurry circulation system, and the slurry transfer system to the dehydrator are maintained at a predetermined high pressure (for example, 3 to 10 MPa).

  Here, when supplying the NGH slurry generated by the generator 2 to the dehydrator, the concentration of the NGH slurry becomes a problem. That is, since NGH is basically in a granular form, if the amount of water that is the slurry liquid is small, the fluidity is extremely lowered and it becomes difficult to transfer the NGH slurry from the generator 2 to the dehydrator. The slurry cannot be stably supplied to the dehydrator.

  Therefore, in this embodiment, a slurry concentration detector 14 is provided in the slurry transfer pipe 13, and the amount of circulating gas and the amount of circulating slurry are adjusted so that the detected NGH slurry concentration falls within a set range (for example, about 20% by weight). At least one of the temperature and the circulating slurry amount is controlled. In this embodiment, in view of the correlation between the NGH slurry concentration and the conductivity of the NGH slurry, a pair of electrodes is provided in the NGH slurry, and a predetermined voltage is applied between these electrodes. The concentration of the NGH slurry is detected by obtaining the conductivity of the NGH slurry from the current that flows.

  According to the present embodiment, the concentration of the NGH slurry can be continuously controlled to a desired value with high accuracy and stability. Therefore, the NGH slurry can be stably transferred to the dehydrator.

  In the present embodiment, the slurry concentration detector 14 is provided in the slurry transfer pipe 13. However, the present invention is not limited to this, and the slurry circulation for returning the NGH slurry extracted from the bottom of the generator 2 to the top of the generator 2. The same effect can be obtained by providing the system.

  Further, the method for detecting the concentration of the NGH slurry is not limited to the method in the present embodiment. For example, a pair of annular coils are provided facing each other in an NGH slurry, and a magnetic field is generated in the coil core by flowing a predetermined alternating current through one coil, and a current is passed through the NGH slurry. It is also possible to generate a magnetic field in the core of the other coil and thereby obtain an electromotive force induced in the other coil. That is, since the induced electromotive force generated in the other coil changes depending on the conductivity of the NGH slurry, the conductivity of the NGH slurry is obtained from the induced electromotive force, and thereby the concentration of the NGH slurry can be detected. . In addition, when such a method is applied, since it is not necessary to immerse a pair of annular coil directly in a NGH slurry, there exists an advantage that it is excellent in corrosion resistance.

It is a figure which shows the gas hydrate slurry manufacturing apparatus of this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gas hydrate slurry manufacturing apparatus 2 Generator 5 Circulating gas blower 8 Circulating slurry pump 9 Cooler 12 Slurry transfer pump 13 Slurry transfer piping 14 Slurry concentration detector

Claims (3)

A generator for producing a slurry containing gas hydrate by hydration reaction of continuously supplied raw material gas and water, and by extracting the raw material gas from the top of the generator and from the bottom of the generator in the gas circulation system for circulating the raw material gas and air diffusion, extracted slurry containing gas hydrate from the bottom of the generator, and the slurry was returned to the top of the generator through a cooler for cooling refrigerant circulating A slurry circulation system that conducts, a slurry transfer pump that extracts a slurry containing gas hydrate from the bottom of the generator and transfers it to a dehydrator, and a gas hydrate concentration in the slurry that is extracted from the bottom of the generator. a slurry concentration detector for detecting, based on the rate, the flow rate control valve for controlling the circulating gas of the raw material gas to be circulated is provided in the gas circulation system, the slurry A flow control valve for controlling the circulation slurry of the slurry being circulated is provided in the circulation system, by controlling at least one of the means for controlling the refrigerant flow rate of the cooler, which is detected by the slurry concentration detector A gas hydrate slurry manufacturing apparatus comprising: control means for controlling the gas hydrate concentration in the slurry within a set range.   The gas hydrate slurry production apparatus according to claim 1, wherein the slurry concentration detector detects a gas hydrate concentration in the slurry upstream of the slurry transfer pump.   The gas hydrate slurry production apparatus according to claim 1, wherein the slurry concentration detector detects a gas hydrate concentration in the slurry circulated by the slurry circulator.

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