JP2001108664A - Gas chromatograph - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas chromatograph having a forcible circulation type air bath oven capable of containing a capillary column of a current normal winding diameter even when a lateral width or a depth size is small. SOLUTION: A crossflow fan 3 is disposed at a lower part in a tank chamber 2 as a fan for forcibly circulating air in an oven for a column so that its rotary shaft is parallel to a door surface 11 to become a side face of the oven, and a capillary column 5 is disposed so that a central axis of a column coil perpendicularly crosses the surface 11. When the fan 3 rotates counterclockwise, an upward flow along an inner surface of a tank wall 12 opposed to the surface 11 is generated. This flow is heated when the flow passes between heaters 4, fed as indicated by an arrow, passed through a gap of the column 5, directed downward while heating the column 5, again sucked to the fan 3 at a bottom of the oven, and thus circulated in the tank.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a gas chromatograph, and more particularly to an oven containing a capillary column.

[0002]

2. Description of the Related Art A gas chromatograph is provided with an oven (constant temperature bath) for accommodating a column for separation and controlling the column at a predetermined temperature. FIG. 2 shows a typical structure of an oven in a conventional gas chromatograph. FIG. 2 (A) is a view of the inside of the tank from the front, and FIG. 2 (B) is a cross-sectional view of the oven from the side. It is.

This is a forced circulation type air bath oven, which is a substantially cubic box-shaped container surrounded by six insulated tank walls 11 to 16 including one opened and closed as a door. An electric heater 4 for heating and a fan 30 for circulating air in the tank are provided in the internal space (tank chamber 2), and a motor 31 for rotating the fan 30 is provided outside the tank.
And a temperature control device (not shown) for adjusting electric power supplied to the heater 4 for controlling the inside of the bath to a predetermined temperature. The air in the tank is sent out rearward by the fan 30 as shown by the arrow in FIG. 2B, and forwards along the guide plate 6 (also serving as a holder for the heater 4) while being heated by the heater 4. The direction of the flow is changed, and circulates through a metal net 21 that partitions the tank chamber 2 back and forth, flows between the capillary columns 5 and returns to the fan 30.

The capillary column 5 is formed by winding a small tube of fused silica having a length of several tens of meters in a coil shape around a wire-made cage 51, and has a winding diameter of 15 to 20 cm. It is attached to the net 21 via a column holder 52 designed so that it can be easily attached and detached (close to the front as viewed from the door side). Normally, a central axis 53 of a coil formed by a capillary column (hereinafter, referred to as a column coil) is one of the six tank walls that can be opened and closed as a door (hereinafter, this surface is referred to as a door surface). To be orthogonal). In a normal gas chromatograph, since the door surface 11 faces the front, in other words, the column coil is mounted so that it looks like a circular ring when viewed from the front. Such an arrangement is required for the convenience of connecting to the road.

For this reason, the inner dimensions of the oven must be larger than the maximum column coil winding diameter (about 20 cm) in both the vertical and horizontal directions. Therefore, in view of a slight clearance between the column coil and the inner surface of the bath wall, and considering the thickness of the heat insulating material of the bath wall, the outer dimensions of the oven are required to be at least about 30 cm both vertically and horizontally. on the other hand,
Regarding the depth dimension of the oven, as shown in FIG. 2B, it is necessary to dispose the capillary column 5 in front of the chamber 2, the fan 30 and the heater 4 in the rear, and further install the motor 31 on the back outside the chamber. , Depth dimension is at least 30
cm is required. After all, conventional gas chromatograph ovens have a height, width and depth of at least 3
At present, it is supposed that a dimension of about 0 cm is required.

A horizontal oven in which FIG. 2 (B) is rotated clockwise by 90 degrees may be rarely used for gas chromatography. In this case, too, the oven has dimensions such as height and height. At least 3 for both width and depth
There is no change in the fact that around 0 cm is required.

[0007]

As described above, in a conventional general-purpose gas chromatograph oven, the height, width,
The depth is required to be at least around 30 cm. As an actual gas chromatograph, equipment such as an electric control unit, a detector, and a sample introduction unit are added in addition to the oven. It was normal. However, in recent years, there is a tendency that the requirements for installing gas chromatographs are diversifying. For example, in order to arrange a large number of devices in a narrow laboratory, a device having a narrow width (width of a frontage) may be required. Depth dimensions may be restricted for purposes such as in-vehicle use, but there is a limit in meeting the various requirements with the oven having the conventional structure as described above.

[0008] In recent years, from the viewpoint of energy saving, a downsizing of a gas chromatograph oven has been required. This is because by reducing the size of the oven, the amount of air in the oven to be heated is reduced, so that the required power amount is also reduced, and the heat dissipation surface area is reduced, thereby reducing the heat loss and contributing to the energy saving effect. Therefore, reduction in any or all of the height, width, and depth is required.

Attempts have been made to reduce the diameter of the capillary column (diameter of the column coil) in order to reduce the size of the oven. However, reducing the diameter of the capillary causes a problem that the capillary column is easily broken. No winding diameter smaller than the current normal winding diameter (15 to 20 cm) is used. Although there is an example in which the diameter of the capillary column is reduced particularly for a special purpose to reduce the size of the oven, this is an example of a gas chromatograph dedicated to a specific use and has no versatility.

The present invention has been made in view of such circumstances, and in particular, has a small width or depth dimension. As a result, it is possible to accommodate a capillary column having a current normal winding diameter while having a smaller volume than conventional ones. It is an object of the present invention to provide a forced circulation type air bath type oven so that it can respond to various demands on the installation place of a gas chromatograph.

[0011]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention uses a cross-flow fan as a fan for forcibly circulating air in a column oven in a gas chromatograph, and a rotating shaft of the cross-flow fan. Was arranged so as to be parallel to the door surface.

[0012]

FIG. 1 shows an embodiment of the present invention. In the same figure, (A) is a view of the inside of the tank with the side door opened, and (B) is a cross-sectional view as viewed from the front. , (B) is not essentially different. In FIG. 1, components having the same functions as those in FIG. In FIG. 1, a cross flow fan 3 characterizes the present invention. What is a cross flow fan?
This is a general term for fans that blow air in a direction perpendicular to the rotating shaft, and is a name for an axial flow fan such as a propeller fan that blows air in the direction in which the rotating shaft extends. A cross-flow fan is also called a tangential fan because it blows air in the tangential direction of a locus circle drawn by the blade tip of the fan as it rotates. As is well known, a cross flow fan has a structure in which a number of blades (blades) are planted along a rotation axis, and in many cases, the length in the rotation axis direction is larger than the diameter of the fan.

The cross flow fan 3 according to the present embodiment.
As shown in FIG. 1, the rotary shaft is attached to a lower portion in the tank chamber 2 so that a rotation axis thereof is parallel to a door surface 11 which is a side surface of the oven. , One end of the rotating shaft is directly connected to the rotating shaft of a motor 31 provided outside the tank wall 16 on the rear side, and the other end is fixed to the tank wall 15 on the front side. It is supported by a bearing 32. On the other hand, the capillary column 5
Are arranged so that the center axis of the column coil is orthogonal to the door surface 11 as in the prior art.

In FIG. 2B, the cross flow fan 3
Rotates counterclockwise to generate an airflow in the circumferential direction of the circle connecting the blade tips of the fan, which is concentrated in one direction by the action of the guide plate 6 and the tank wall 1 facing the door surface 11.
2 is an upward airflow along the inner surface. This air flow is heated when passing between the inner surface of the tank wall 12 facing the door surface 11 and the heater 4 horizontally stretched in the space sandwiched by the guide plate 6, and is guided to the guide plate 6. It reaches the top of the oven, where it is redirected, heading down while heating it by passing it through the gap in the capillary column 5 which is wound on a cage 51 and attached to the guide plate 6 with a column holder 52, at the bottom of the oven. It is circulated in the tank by being sucked into the cross flow fan 3 again. The arrows in FIG. 1B show the outline of the airflow circulating in the tank.

As shown in FIG. 1A, since the cross flow fan 3 is long in the axial direction, a wide parallel air flow spreads over substantially the entire inside of the tank, and air circulation with little turbulence is efficiently performed. Can be expected to be done. In addition, it is a feature of the present invention that the rotation axis of the cross flow fan 3 is provided in parallel with the door surface 11, whereas the center axis of the column coil is arranged perpendicular to the door surface 11 as in the past. Have been. By arranging in this manner, it is possible to design the oven to reduce the depth or width of the oven to about half that of the conventional oven, and it is possible to provide a gas chromatograph that can cope with restricted installation locations. .

FIG. 1 shows an embodiment of the present invention, and many other different configurations are conceivable in practicing the present invention. For example, it is not necessary to place the cross flow fan at the bottom of the tank,
A configuration in which a fan is provided on the upper portion is also possible, and a plurality of fans may be arranged vertically.

Conventionally, in a gas chromatograph oven, a part of the oven is provided with a ventilation window communicating with the outside of the tank, and the door is opened and closed by a door called a flapper to allow air in the tank to escape or to take in cool air outside the tank. Thereby, a structure capable of rapidly lowering the temperature in the tank was adopted, but such a flapper can be applied to the gas chromatograph oven according to the present invention,
The present invention does not prevent or impair the application of the flapper.

[0018]

Since the present invention is configured as described above, it is possible to design an oven capable of accommodating a current capillary column having a normal winding diameter while keeping the depth or width dimension at about half that of the conventional one. As a result, a gas chromatograph that can be used in installation locations with restrictions can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of the present invention.

FIG. 2 is a diagram showing an example of a conventional gas chromatograph oven.

[Explanation of symbols]

 2 tank chamber 3 cross flow fan 4 heater 5 capillary column 11 door surface 31 motor 52 column holder

Claims (1)

[Claims] 1. A box formed of six walls including one door surface, comprising a heater for heating and a cross flow fan as a fan for circulating air in the tank. A gas chromatograph comprising a column oven, wherein the rotation axis of the cross flow fan is arranged parallel to the door surface.