JP2005257528A - Flow through type nmr probe for measuring high temperature - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flow through type NMR probe for measuring high temperatures, in which sufficient countermeasures to heat are implemented, and a flow through type sample tube 2 is easily detached. <P>SOLUTION: The flow through type NMR probe is equipped with the flow through type sample tube which is arranged so as to go through an NMR measuring section; two heating means which are respectively arranged above and below the NMR measuring section; a gas channel which guides the gas heated by the heating means, arranged close to below the NMR measuring section to an opening formed near the lower side of the NMR measuring section, and which exhausts the gas upward above the NMR measuring section through the periphery of the flow through type sample tube from the opening; a first heat transfer pipe which extends upward from a region near the opening of the gas channel, covers an area below the measuring section and transfers heat of the gas to the flow through type sample tube; and a second heat transfer pipe, which is in thermal contact with the heating means arranged above the NMR measuring section, extends downward from the heating means, covers an area above the measuring section and transfers heat of the heating means to the flow through type sample tube. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a flow-through NMR probe for high-temperature measurement used for measurement of a supercritical fluid in a high-resolution nuclear magnetic resonance (NMR) apparatus.

  The flow-through NMR probe for high-temperature measurement is an important attachment that is indispensable when researching physical properties using an NMR apparatus. In particular, in the supercritical fluid research field where the temperature of the measurement sample needs to be maintained at a high temperature of 400 ° C. or higher, it is no exaggeration to say that the flow-through NMR probe for high temperature measurement is an indispensable element.

  FIG. 1 shows the structure of a conventional flow-through NMR probe for high-temperature measurement. In the figure, reference numeral 1 denotes a sample injection pipe into which a high-temperature and high-pressure measurement sample such as supercritical water is injected. The sample injection pipe 1 is provided in the probe main body and communicates with a straight tubular flow type sample tube 2 having openings in the upper and lower sides. The sample injected from the sample injection pipe 1 flows through the inside of the flow type sample tube 2, and the NMR signal is detected by the detection coil 3 arranged so as to surround the flow type sample tube 2. The sample after measurement is discharged to the outside of the probe through the sample discharge pipe 4 communicating with the lower opening of the flow-through sample tube 2.

  In order to change the temperature of the sample, air heated by the heater attached to the temperature-variable heater attachment portion 5 is caused to flow around the flow-through sample tube 2 through the temperature-variable air introduction double tube 6. The sample temperature in the flow type sample tube 2 is changed by heat exchange between the flow type sample tube 2 and air. The air subjected to the change in the sample temperature is exhausted to the outside from the upper part of the probe. In order to maintain the temperature inside the flow-through sample tube 2 at a high temperature of 400 ° C. or higher, it is necessary to employ a high power heater.

Japanese Patent Laid-Open No. 2000-241518.

JP 2001-281314 A.

JP 2002-168932 A.

JP 2002-196056 A.

  As technical problems of the conventional flow-type NMR probe for high-temperature measurement shown in FIG. 1, the following points are raised.

  1. For the reason that the position of the heater for air heating is away from the position of the sample, the thermal efficiency of the sample heating is poor, the heat leak is large, and it is extremely difficult to heat the sample to 400 ° C. or higher. In addition, if the sample is forcibly heated to 400 ° C or higher, the entire probe becomes a high temperature of several hundred degrees, and there are adverse effects such as damage to the probe itself and damage to the superconducting magnet that forms part of the NMR apparatus. Produce.

  2. The heated air has a structure that is blown from the lower lateral direction of the flow type sample tube 2, and since the heated air does not flow uniformly along the flow type sample tube 2, the temperature uniformity of the sample decreases. Further, since there is no suitable sealing member such as an O-ring that can withstand a high temperature of 400 ° C. or higher, the heated air is not only exhausted upward of the flow-through sample tube 2 but also the flow-through sample tube 2. The problem of leaking from below occurs.

  3. Since the flow-through sample tube 2 is incorporated and fixed in the probe main body, it usually has a structure that cannot be removed by the user.

  The present invention has been made in view of the above-described points, and an object of the present invention is to provide a flow-through NMR probe for high-temperature measurement in which a flow-rate sample tube 2 is easily removed and the flow-through sample tube 2 is easily removed. It is in.

In order to achieve this object, the flow-through NMR probe for high temperature measurement of the present invention is
A flow-through sample tube disposed through the NMR measurement section;
Two heating means provided above and below the NMR measurement section;
The gas heated by the heating means provided below the NMR measurement unit is led to an opening provided near the lower side of the NMR measurement unit, and the NMR is passed through the circumference of the flow-through sample tube from the opening. A gas flow path for exhausting upward of the measurement unit;
A first heat transfer pipe that extends upward from the vicinity of the opening of the gas flow path, covers a region below the measurement unit, and conducts heat of the gas to a flow-through sample tube;
It is in thermal contact with the heating means provided above the NMR measurement area, extends downward from the heating means, covers the area above the measurement unit, and heats the heating means to the flow-through sample tube And a second heat transfer pipe that conducts the heat.

  Further, the heat transfer pipe is made of gold or a pipe made of a metal having substantially the same thermal conductivity, heat resistance, and non-magnetic properties as gold.

  In addition, a plurality of heat insulating members are concentrically provided around the heating means provided below the NMR measurement unit.

  Of the plurality of heat insulating members, the heat insulating member disposed on the innermost side is a glass vacuum double tube.

  Also, a gold thin film having a mirror-finished surface, or a thin film made of a metal having a melting point of 800 ° C. or higher, which is close to the surface of the glass vacuum double tube, is applied. It is said.

  The heat insulating member disposed on the outermost side among the plurality of heat insulating members is a water-cooled metal tube.

  Further, a metal thin film is provided between the gold thin film and the water-cooled metal tube through an air layer.

  In addition, the detection coil part including the flow-through sample tube and the probe body including the electric circuit part such as the tuning matching circuit can be separated, and the high frequency band is provided between the detection coil part and each electric circuit. It is characterized by connecting with a connector.

  A flow-through sample tube disposed through the NMR measurement section, two heating means provided above and below the NMR measurement section, and a gas heated by the heating means provided below the NMR measurement section A gas channel that leads to an opening provided in the vicinity of the lower side of the NMR measurement unit and exhausts from the opening to the upper side of the NMR measurement unit via the periphery of the flow-through sample tube, and the gas channel A first heat transfer pipe that extends upward from the vicinity of the opening and covers a region below the measurement unit, and conducts the heat of the gas to the flow-through sample tube, and the above-described NMR measurement region. A second heat transfer pipe that is in thermal contact with the heating means, extends downward from the heating means, covers a region above the measurement unit, and conducts heat of the heating means to the flow-through sample tube; Because it is equipped, sufficient high temperature measures are taken, distribution type Easy removal of the postal tube 2, it has become possible to provide a flow-through NMR probe for high temperature measurements.

  In order to reliably obtain a high temperature of 400 ° C. or higher with a flow-through NMR probe, it is necessary to strengthen the heater. Therefore, compared with the heater for heating used in the conventional probe, the heater power is increased about 10 times to about 500 W. In addition, the following points were improved in order for the probe to withstand the heater power.

  1. As a measure to improve the heat insulation efficiency, a heater was put in a glass vacuum double tube, and a silver mirror was applied to the inside of the glass vacuum double tube with an aluminum material. A thin film such as a thin film that has a melting point as high as 800 ° C or higher and can be mirror-finished, can be processed into a thin film, wrapped in close contact with the surface of a glass vacuum double tube, and has the same effect as a conventional silver mirror I tried to get it. As a result, the aluminum material can withstand a high temperature of 600 ° C. or higher, which cannot maintain a silver mirror. In addition, a narrow space is provided around the vacuum double tube made of glass, and a thin air layer (air has very low thermal conductivity if there is no convection) and another metal thin film with a mirror finish, The heat insulation efficiency was improved. For this metal thin film, an inexpensive metal such as an aluminum material having poor heat resistance is used. This is because the temperature has already decreased considerably at this site.

  2. As a measure for improving heat leakage, a water-cooled metal tube was provided outside the metal thin film surrounding the glass vacuum double tube to completely prevent heat leakage around the probe.

  3. As a measure for improving the temperature uniformity, an auxiliary heater was provided above the NMR measurement unit to reduce the temperature gradient in the vertical direction. Also, inside the auxiliary heater, a metal heat transfer pipe that extends downward from the auxiliary heater and covers the area above the measurement unit to conduct the heat of the auxiliary heater, while the flow type below the measurement unit At the opening part of the heated air sprayed to the sample tube, a metal heat transfer pipe that extends upward from the sprayed part and covers the area below the measurement part and conducts the heat of the heated air, respectively. Provided. These auxiliary heaters and heat conduction by two metal heat transfer pipes prevent temperature nonuniformity.

  4). As a measure to improve the attachment and detachment of the flow-through sample tube, the detection coil portion including the flow-through sample tube and the probe body including the electric circuit portion such as a tuning matching circuit can be separated from each other. The circuit is connected with a high frequency connector.

  FIG. 2 shows a cross-sectional view of a flow-through NMR probe for high temperature measurement according to the present invention. In the figure, 11 is an air intake. Air such as nitrogen gas is fed into the probe from the air intake port 11, and electric power is supplied from the heater power supply connector 12 to flow current to the heater 13. Thereby, the heater generates heat, and the fed air is heated.

  The temperature of the heated air is measured by a temperature sensor 14 such as a thermocouple. The position 14 in the figure is a temperature measurement point. While measuring the temperature at the position 14, the current passed through the heater 13 is adjusted so that the air temperature becomes the target temperature.

  The heated air is blown from the opening provided immediately above the temperature sensor 14 toward the flow type sample tube 17, and the sample in the flow type sample tube 17 is passed through the periphery of the flow type sample tube 17. Heat. In order to obtain a high temperature of 400 ° C. or higher, a vacuum double tube or the like serving as a flow path for heated air is insulated and insulated with a heat insulating material, and a high-power heater is adopted as the heater 13.

  Further, an auxiliary heater 19 is provided on the upper part of the flow type sample tube 17, and the sample injected from the sample injection pipe 25 and flowing into the flow type sample tube 17 through the first joint 20 is preheated. The sample that has passed through the flow-through sample tube 17 is discharged to the outside of the probe through the sample discharge pipe 26 via the second joint 21.

  The glass vacuum double tube 15 that insulates the heater 13 for air heating from the outside is generally internally subjected to silver mirror treatment using aluminum or the like. The temperature of the heater 13 becomes 700 ° C. or more, and the aluminum of the silver mirror is melted and cannot be used. Therefore, instead of the silver mirror, the glass vacuum double tube 15 is surrounded by a glass fiber heat insulating material. Wrapped with. However, this method has a problem that the thickness is increased.

  However, the mirror-finished 0.02 mm-thick pure gold thin film or the metal thin film 27 made of a metal having a melting point equal to or higher than 800 ° C. is used as the glass vacuum double tube 15. If the technique of winding around is employed, an effect almost equivalent to that obtained when a glass vacuum double tube treated with a silver mirror is used can be obtained.

  In order to further increase the heat insulating effect, a metal thin film (not shown) having a mirror finish, for example, an aluminum thin plate having a thickness of 0.1 to 0.2 mm, was attached around the space with a space of about 1 mm (not shown). This metal thin film layer has a higher heat insulation effect as the number of layers increases. Therefore, it is also effective to wind in a spiral.

  Further, when the heat of the heater 13 passes through the heat insulating material and is transmitted to the entire probe, the electronic circuit and the superconducting magnet are adversely affected. Therefore, the heater 13 is combined with the glass vacuum double tube 15 and the metal thin film 27 enclosing it. It was placed in a water-cooled metal pipe 16 to completely prevent heat leakage.

  In addition, two heat transfer pipes 18 made of a precious metal such as gold that does not oxidize even at high temperatures are provided so that the temperature of the sample flowing through the flow-through sample tube 17 can be made uniform over 400 ° C. over a wide range. The first heat transfer pipe extends upward from the opening portion of the heated air outlet, covers the region below the measurement unit, and conducts the heat of the air. The second heat transfer pipe is disposed in thermal contact with the auxiliary heater 19 provided above the NMR measurement unit, extends downward from the auxiliary heater 19, and has a region above the measurement unit. Covering and conducting the heat of the auxiliary heater 19. The flow-through sample tube 17 is inserted inside these two heat transfer pipes 18 and heats the sample in the flow-through sample tube 17 through the two heat transfer pipes 18.

  The first heat transfer pipe has a structure in which the lower part is processed into a bowl shape, and the heated air has a structure that is unlikely to leak downward in the flow-through sample tube 17.

  Further, the detection coil part including the flow-through sample tube and the probe main body part including the electric circuit part such as the tuning matching circuit can be easily separated by removing the fixing screw 23.

  FIG. 3 shows a cross-sectional view of a detection coil portion including a flow-through sample tube. In the figure, reference numeral 36 denotes a flow-through sample tube. Removal of the flow-through sample tube 36 from the detection coil portion is performed as follows.

  First, the spacer 31 is removed. Next, the high-pressure sample tube holder 32 is shifted to the left and the stopper 35 is removed. As a result, the high-pressure sample tube holder 32 can be removed from the flow-through sample tube 36. Next, by removing the sample tube fixing screw 37, the flow-through sample tube 36 can be pulled out from the detection coil portion.

  It can be widely used for a flow-through NMR probe for high temperature measurement.

It is a figure which shows the conventional flow-type NMR probe for high temperature measurement. It is a figure which shows one Example of the flow-type NMR probe for high temperature measurement concerning this invention. It is a figure which shows one Example of the flow-type NMR probe for high temperature measurement concerning this invention.

Explanation of symbols

1: sample injection pipe, 2: flow-through sample tube, 3: detection coil, 4: sample discharge pipe, 5: temperature-variable heater mounting portion, 6: temperature-variable air introduction double tube, 11: air intake port 12: Heater power connector, 13: Heater, 14: Temperature sensor, 15: Glass vacuum double tube, 16: Water-cooled metal pipe, 17: Flow-through sample tube, 18: Heat transfer pipe, 19 : Auxiliary heater, 20: first joint, 21: second joint, 22: high frequency connector, 23: fixing screw, 24: detection coil, 25: sample injection pipe, 26: sample discharge pipe, 27: metal thin film, 28: Water supply pipe to water-cooled metal pipe, 31: Spacer (split ring), 32: High-pressure sample tube holder, 33: Fixing screw, 34: High-pressure pipe joint, 35: Stopper (split ring), 36: Distribution type Trial Tube, 37: sample tube fixing screws

Claims (8)

A flow-through sample tube disposed through the NMR measurement section;
Two heating means provided above and below the NMR measurement section;
The gas heated by the heating means provided below the NMR measurement unit is led to an opening provided near the lower side of the NMR measurement unit, and the NMR is passed through the circumference of the flow-through sample tube from the opening. A gas flow path for exhausting upward of the measurement unit;
A first heat transfer pipe that extends upward from the vicinity of the opening of the gas flow path, covers a region below the measurement unit, and conducts heat of the gas to a flow-through sample tube;
It is in thermal contact with the heating means provided above the NMR measurement area, extends downward from the heating means, covers the area above the measurement unit, and heats the heating means to the flow-through sample tube A flow-through NMR probe for high-temperature measurement, comprising a second heat transfer pipe that conducts. The flow-through NMR probe for high temperature measurement according to claim 1, wherein the heat transfer pipe is made of gold or a pipe made of a metal having substantially the same thermal conductivity, heat resistance, and non-magnetic properties as gold. The NMR probe for high-temperature measurement according to claim 1 or 2, wherein a plurality of heat insulating members are concentrically provided around the heating means provided below the NMR measurement unit. The flow-through NMR probe for high-temperature measurement according to claim 3, wherein among the plurality of heat insulating members, the heat insulating member disposed on the innermost side is a glass vacuum double tube. A gold thin film having a mirror-finished surface, or a thin film made of a metal having a melting point of about 800 ° C. or more, which is close to the surface of the glass vacuum double tube, is used. The flow-through NMR probe for high temperature measurement according to claim 3 or 4. 6. The flow-through NMR probe for high temperature measurement according to claim 3, wherein the heat insulating member arranged on the outermost side among the plurality of heat insulating members is a water-cooled metal tube. The flow-through NMR probe for high-temperature measurement according to claim 4, wherein a metal thin film is provided between the gold thin film and the water-cooled metal tube via an air layer. The structure is such that the detection coil part including the flow-through sample tube can be separated from the probe body including the electric circuit part such as the tuning matching circuit, and a high frequency connector is provided between the detection coil part and each electric circuit. The flow-through NMR probe for high-temperature measurement according to claim 1, wherein the NMR probe is connected.

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