JP2009029946A - Concentration measuring method for gas hydrate, and device therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a concentration measuring method for a gas hydrate in a manufacturing device for the gas hydrate, measuring a generated concentration of the gas hydrate in line and in situ, in the manufacturing device for manufacturing the gas hydrate by bringing raw gas into gas-liquid contact with raw water. <P>SOLUTION: A densitometer K1 for measuring the concentration of the gas hydrate is provided in a slurry pipe L2 for transferring slurry generated by a generation means, in the manufacturing device for the gas hydrate having the generation means for generating the slurry comprising the gas hydrate and unreacted water, by introducing the raw gas G1 and the raw water W1 into a generator 1 held at prescribed pressure and at a prescribed temperature, to react each other. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a gas hydrate concentration measuring device in a gas hydrate production apparatus, more specifically, a gas hydrate and unreacted water by reacting a raw material gas such as methane with raw water at a predetermined pressure and temperature. In the gas hydrate manufacturing apparatus which produces | generates the slurry which consists of this, It relates to the gas hydrate concentration measuring apparatus in the gas hydrate manufacturing apparatus characterized by measuring the density | concentration of the gas hydrate in the said slurry.

  In recent years, natural gas mainly composed of methane has attracted attention as a clean energy source. In order to efficiently transport or store such natural gas, it is known to produce gas hydrate by reacting the natural gas and raw water.

  As a method for producing gas hydrate, a gas-liquid stirring method (for example, Patent Document 1) that stirs while blowing a raw material gas into raw material water, and a water spray method (for example, Patent Document 2) that sprays raw material water into the raw material gas. ) The gas hydrate produced by the gas-liquid stirring method or water spray method is in the form of a powder and is produced as a slurry mixed with unreacted water. More preferably, unreacted water and gas hydrate are separated from the slurry by a dehydrator arranged on the downstream side to produce a gas hydrate having a relatively low water content.

  In such a gas hydrate production apparatus, knowing the concentration of gas hydrate in the slurry is important for grasping the operation state of the apparatus. As a method for measuring the concentration of gas hydrate in the slurry, an operator usually takes out a part of the slurry with a sampling tube or the like and analyzes the sample.

On the other hand, Patent Document 3 describes that the production state of carbon dioxide hydrate can be grasped by measuring the electrical conductivity of the liquid.
JP 2000-302701 A JP 2000-264852 A JP 2002-273205 A

  By the way, the above-mentioned method for sampling the gas hydrate and measuring its concentration is a discontinuous batch operation and is an off-line measurement. Further, in order to obtain the measurement result of the gas hydrate concentration, it takes a long time. (E.g., 1-2 hours) was required. In addition, since manual work is involved, there is a possibility that the measured value of the gas hydrate concentration may vary.

  On the other hand, according to the method of Patent Document 3, it is possible to detect the production of carbon dioxide hydrate by conductivity, but since a specific method for quantifying the concentration of gas hydrate is not disclosed, Concentration quantification is expected to be difficult.

  The present invention has been made to solve the conventional problems as described above, and is configured as follows.

1) A gas hydrate having a generating means for generating a slurry composed of gas hydrate and unreacted water by introducing and reacting a raw material gas and raw water into a generator holding a predetermined pressure and temperature. In the manufacturing apparatus, a concentration meter for measuring a concentration of gas hydrate is provided in a slurry tube for transferring the slurry generated by the generating means.

2) A part of the slurry pipe is narrowed down to a small diameter pipe, and a densitometer for measuring the concentration of gas hydrate is provided in the small diameter pipe portion.

3) A screw pump is disposed in the slurry tube, and a concentration meter for measuring the concentration of gas hydrate is provided on the discharge side of the screw pump.

4) A rising portion in which a part of the slurry tube is formed substantially vertically is provided, and a concentration meter for measuring the concentration of gas hydrate is provided in the rising portion.

5) It is characterized in that at least one of pressure and temperature in the generator is controlled by a gas hydrate concentration signal measured by the densitometer.

6) The densitometer is a near-infrared spectrometer.

(A) The hydrate and unreacted water in the hydrate slurry are separated when the slurry sample is measured in a stationary state, whereas the present invention determines the concentration of the slurry transferred in the slurry tube. Since direct measurement is performed, accurate hydrate concentration can be directly measured continuously and in real time.

(B) The concentration of the slurry can be continuously measured by the densitometer, and the measured value is grasped in real time, so that the operating conditions and the like in the downstream process can be set in advance, and the operating efficiency Will improve. Moreover, by setting the operating conditions and the like in advance, it is possible to stably produce gas hydrate products of uniform quality (for example, compression-molded pellets).

(C) Since the throttle part is provided in the slurry tube and the densitometer is attached to the throttle part, mixing of the slurry at the throttle part is further promoted. Therefore, the gas hydrate in the slurry is more uniformly distributed, and as a result, the concentration of the gas hydrate can be measured more accurately.

(D) Since the slurry pump is disposed in a part of the slurry pipe and the concentration meter is attached to the discharge side of the slurry pump, the slurry is positively stirred and mixed by the slurry pump. Therefore, the gas hydrate in the slurry is more evenly distributed. Therefore, a more accurate gas hydrate concentration can be measured.

(E) Since a vertical portion is provided in the slurry tube and a densitometer is attached to the vertical portion, separation of the slurry flowing through the vertical portion from unreacted water is suppressed. As a result, the concentration of gas hydrate can be measured accurately.

(F) Since the gas hydrate concentration in the slurry can be measured on the spot in real time, at least one of the pressure and temperature in the generator can be controlled by the measured concentration signal, and the operation of the generator can be controlled. Can be automated. As a result, the production efficiency of gas hydrate is improved.

(G) Since a near-infrared spectrometer is used as the densitometer, the gas hydrate concentration can be measured quickly and accurately. Accordingly, stable operation of the generator and efficient gas hydrate production are possible.

  Hereinafter, an embodiment of a gas hydrate concentration measuring apparatus in a gas hydrate manufacturing apparatus according to the present invention will be described with reference to FIGS.

Example 1
FIG. 1 is a schematic configuration diagram of a gas hydrate production apparatus equipped with a gas hydrate concentration measuring apparatus according to the present invention. The gas hydrate production apparatus as shown in FIG. 1 uses a gas hydrate generator 1 using a gas-liquid stirring method. The generator 1 includes a pressure vessel 5, a heat exchanger 7 that cools the raw water in the pressure vessel 5, a stirring blade 6 a and a gas ejection pipe 9 (sparger) disposed inside the pressure vessel 5, It comprises a drive machine M1 such as an electric motor for rotating a shaft 6b provided with blades 6a.

  Further, the generator 1 includes a gas supply line L5 for introducing a raw material gas G1 such as methane, a water supply line L6 for introducing a raw material water W1, and a gas circulation line L1 for the raw material gas G1 having a gas circulation blower B1. The brine circulation line L10 having the heat exchanger 7, the slurry line L2 having one end connected to the dehydration tower 2 described later, and the return line L3 of the unreacted water W2 are respectively connected. The slurry line L2 is provided with a slurry pump P1, and the return line L3 is provided with a pump P2. Further, a slurry circulation line L2R is provided in the slurry line L2.

  Further, an in-line measurement type densitometer K1 is attached to the slurry line L2, and the concentration signal V1 measured by the densitometer K1 is input to the arithmetic unit 40 as shown in FIG. . The computing device 40 comprises a computing device 41, a storage device 43, and a comparator 42, 44 is a display, 45 is an output unit, and 46 is a control signal transmitter. The rotational speed of the driving device M1 and the amount of slurry circulation are adjusted.

  The densitometer K1 is a near-infrared spectroscopic analyzer, for example, a gas hydrate manufacturing apparatus that uses an explosion-proof explosion-proof structure with an explosion-proof grade Exd IIB T4 or higher and uses an explosive gas such as methane gas as a raw material gas. Can be used safely. In addition, the gas hydrate is irradiated with at least two light beams having different wavelengths, and the reflected light from the gas hydrate is condensed on a detector to absorb infrared rays according to the concentration of unreacted water contained in the gas hydrate. The water content is measured from the amount. Therefore, the response is good and the measurement time is very short.

  The concentration of the gas hydrate h1 contained in the gas hydrate slurry S measured by the densitometer K1 is output as a signal V1, and this signal V1 is input to the calculator 41 constituting the calculation device 40, where the concentration d1 Is now required. The density d1 is input to the comparator 42, compared with a predetermined density d2 input in advance in the storage device 43, and the result is output to the display 44 and the output unit 45 as necessary. It has become. A signal V4 output from the comparator 42 is input to the control signal transmitter 46, and a control signal V5 for controlling the driving machine M1 of the generator 1 based on the signal V4 is output from the control signal transmitter 46. It has become so.

  The dehydration tower 2 is constituted by a cylindrical main body 11, a drain hole 11 a is provided in the upper portion, the drain hole 11 a is covered, and a drain chamber 12 is formed around the cylindrical main body 11. The dehydration tower 2 is connected to the slurry line L2, the return line L3 of the unreacted water W2, and the extraction line L4 of the gas hydrate h1, and an exhaust pipe L7 is attached to the drain chamber 12. It has been.

  The gas G2 in the drainage chamber 12 is exhausted from the exhaust line L7 through the exhaust pipe L7, and the pressure A2 in the drainage chamber 12 is lower than the pressure A1 in the dehydration tower 2. Therefore, the unreacted water W2 is sucked from the drainage chamber 12 side through the drainage hole 11a and drained efficiently.

  The gas hydrate h2 dehydrated in the dehydration tower 2 is supplied to a compression molding machine 3 including a pair of molding rolls 23a and 23b provided with a screw type transfer device 21 in a hopper 22. In the molding machine 3, the gas hydrate h2 is filled in molding recesses (not shown) formed on the surfaces of the molding rolls 23a and 23b, and compressed with the rotation of the rolls 23a and 23b to be molded into pellets. It has become. The gas hydrate pellets h3 thus molded are transferred to a storage tank (not shown) and stored.

  In the gas hydrate manufacturing apparatus configured as described above, a predetermined temperature and pressure, for example, a predetermined pressure A1 and a temperature T1 selected from the range of 3 to 10 MPa and a temperature of 0 to 10 ° C. are maintained. The raw material gas G1 from the gas supply line L5 and the raw water W1 from the water supply line L6 are respectively introduced into the pressure vessel 5 of the generator 1 that is installed. The raw material gas G1 is supplied to the sparger 9 via the gas circulation line L1 by the gas circulation blower B1, and is stirred from the raw water W1 by the stirring blade 6a rotated by the driving machine M1 and gas hydrate. And a slurry S1 (mixed hydrate) composed of unreacted water W2.

  The reaction heat generated in the gas hydrate generation process is removed by the heat exchanger 7 provided in the brine circulation line L10, and the inside of the pressure resistant vessel 5 is maintained at the selected predetermined temperature T1.

  The slurry S thus produced is supplied to the dehydration tower 2 via the slurry line L2 by the slurry pump P1, and unreacted water W2 is drained through the drain holes 11a in the process of rising in the dehydration tower 2. A gas hydrate h2 having an increased gas hydrate content is generated.

  As shown in FIG. 2, the slurry line L2 is formed by narrowing the line L2 to form a small-diameter pipe 4. Further, the small-diameter pipe 4 is provided with a concentration meter K1 for measuring the concentration of the gas hydrate h1. ing.

  In the slurry line L2, it is preferable to set the inner diameter ratio between the two tubes so that the flow rate of the slurry S in the small-diameter tube 4 is about 2 to 5 times that of a normal tube. However, there is a case where the production amount is large and the transfer speed is high, or the production amount is small and the transfer speed is low. In addition, a flow meter (not shown) may be provided in the small diameter tube 4 so that the flow rate is in a predetermined range.

  The small-diameter tube 4 prevents the gas hydrate h1 and unreacted water w2 in the slurry S from being separated due to the difference in specific gravity, and the sample passes through the measurement probe portion of the densitometer K1 at high speed. As a result, the average concentration can be measured.

  That is, when the processing speed of the downstream apparatus (for example, the dehydration tower) is relatively gentle, the transfer speed of the slurry S becomes low, and the concentration of the gas hydrate h1 measured by the densitometer K1 tends to become partial. Since the flow rate is increased by reducing the pipe line, it becomes possible to measure a more average concentration, and the measurement error is reduced.

  Then, the signal V1 from the concentration meter K1 is input to the calculator 41 that constitutes the control device 40, and the concentration d1 of the gas hydrate h1 in the slurry S1 is obtained. The signal V2 having the density d1 is input to the comparator 42 and compared with the signal V3 having a predetermined density d2 stored in the storage device 43 in advance. When the density d1 (measured value) is out of the range of the predetermined density d2 (set value), the signal V4 is input to the control signal generator 46, where the control signal V5 is generated. The rotational speed of the driving machine M1 of the generator 1 is controlled by the control signal V5.

  That is, when the measured concentration d1 is higher than the set concentration d2, the stirring speed in the generator 1 is increased. When the measured density d1 is lower than the set density d2, control opposite to the above is performed.

  According to this embodiment, even when a slight gas hydrate concentration deviation occurs in the upper, middle, and lower portions of the piping of the slurry line L2, the flow rate is rapidly increased in the throttle portion (small-diameter pipe). Since the liquids are mixed, the gas hydrate concentration can be measured more accurately than when a concentration meter is provided in the slurry tube.

  In the present embodiment, the case where the generator 1 produces gas hydrate by the gas-liquid stirring method has been shown, but of course, the generator 1 can also be applied to the case where gas hydrate is produced by the water spray method.

  In the present embodiment, only the stirring speed of the generator is adjusted, but the present invention is not limited to this. For example, when the measured concentration d1 is higher than the set concentration d2 (when the measured water content is lower than the set), the supply amount of the slurry S supplied into the dehydration tower 2 is increased, or the drainage chamber Control may be performed to increase the pressure A2 in 12 to reduce the pressure difference from the pressure A1 in the dehydration tower 2, or to reduce the temperature in the generator 1.

(Example 2)
The present embodiment is characterized in that the slurry pump P1 provided in the slurry line L2 is a screw pump as shown in FIG.

  The present embodiment is also applied to a gas hydrate manufacturing apparatus as shown in FIG. 1 as in the first embodiment. The same reference numerals as those in the first embodiment denote the same members, and the description thereof is omitted.

  As shown in FIG. 4, a screw pump 8 is provided in the slurry line L <b> 2, and a densitometer K <b> 1 is installed at the discharge port of the screw pump 8.

  The screw pump 8 is configured to pump the gas hydrate slurry S with stirring and mixing by the screw blades 8a, and the concentration distribution of the hydrate h1 of the discharged slurry S is uniform.

  In the present embodiment, it is desirable that the measurement probe of the densitometer K1 is disposed in the vicinity of the discharge port of the slurry pump P1. That is, the hydrate h1 and the unreacted water w2 in the gas hydrate slurry S that are uniformly mixed by being stirred and mixed by the screw are easily separated due to the difference in specific gravity.

  According to this embodiment, the gas hydrate h1 of the gas hydrate slurry S and the unreacted water w2 are uniformly mixed, so that the concentration measured by the densitometer K1 becomes more accurate. Therefore, it becomes possible to control the operating conditions more strictly and to stably produce a gas hydrate having a certain quality.

(Example 3)
This example is for preventing separation into the hydrate h1 and the water w2 due to the difference in specific gravity between the gas hydrate h1 and the unreacted water w2 in the slurry S. It is characterized by raising a part of the piping.

  The present invention is applied to the same gas hydrate production apparatus as in the above embodiment, and the description of the same reference numerals is omitted.

  As shown in FIG. 5, a part of the slurry line L2 is a vertical pipe L2b, and the slurry S flows through the vertical pipe L2b from below to above at a predetermined flow rate. A concentration meter K1 is provided in the vertical pipe L2b to measure the concentration of the gas hydrate h1 in the gas hydrate slurry S.

  According to this embodiment, the simple structure prevents the gas hydrate h1 from floating and being separated from the unreacted water w2. Further, as in the above embodiment, the stirring speed of the generator 1 and the differential pressure between the drainage chamber 12 of the dehydration tower 2 and the cylindrical body 11 are automatically adjusted based on the signal V1 of the concentration d1 measured by the densitometer K1. As a result, a gas hydrate having a constant quality can be produced stably.

It is a schematic block diagram of the gas hydrate manufacturing apparatus which concerns on this invention. It is the schematic of the slurry line in the gas hydrate manufacturing apparatus which concerns on this invention. It is the schematic of the slurry pump in the gas hydrate manufacturing apparatus which concerns on this invention. It is a figure of the other embodiment of the slurry line in the gas hydrate manufacturing apparatus which concerns on this invention. It is a figure of other embodiment of the slurry line in the gas hydrate manufacturing apparatus which concerns on this invention.

Explanation of symbols

K1 Densitometer 1 Generating device 2 Dehydrating device 3 Molding device 4 Small diameter tube 5 Pressure vessel 6 Stirrer 6a Stirring blade 6b Shaft 7 Heat exchanger 8 Screw pump 9 Sparger 11 Tubular body 11a Drain hole 12 Drainage chamber 15 Screw conveyor 17 Stirrer 17a Stirring blade 17b Rotating shaft 21a Screw blade 21b Shaft 22 Hopper 23a, 23b Forming roll L2b Vertical tube V1, V2, V3, V4, V5 Signal

Claims (6)

A gas hydrate manufacturing apparatus having generating means for generating a slurry composed of gas hydrate and unreacted water by introducing and reacting raw material gas and raw water to a generator holding a predetermined pressure and temperature In
An apparatus for producing a gas hydrate comprising a concentration meter for measuring a concentration of a gas hydrate in a slurry tube for transferring a slurry produced by the producing means.   The apparatus for producing a gas hydrate according to claim 1, wherein a part of the slurry pipe is narrowed to a small diameter pipe, and a concentration meter for measuring the concentration of the gas hydrate is provided in the small diameter pipe portion.   The gas hydrate manufacturing apparatus according to claim 1, wherein a screw pump is disposed in the slurry pipe, and a concentration meter for measuring the concentration of the gas hydrate is provided on the discharge side of the screw pump.   The apparatus for producing a gas hydrate according to claim 1, wherein a rising portion in which a part of the slurry tube is formed substantially vertically is provided, and a concentration meter for measuring the concentration of the gas hydrate is provided in the rising portion. .   5. The gas hydrate manufacturing apparatus according to claim 1, wherein at least one of pressure and temperature in the generator is controlled by a gas hydrate concentration signal measured by the densitometer.   6. The gas hydrate manufacturing apparatus according to claim 1, wherein the densitometer is a near-infrared spectrometer.

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