JP3882336B2 - Gas chromatograph oven - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a gas chromatograph oven that accommodates a gas chromatograph column in its internal space and adjusts the temperature in order to perform gas chromatography at a predetermined temperature.
[0002]
[Prior art]
FIG. 1 shows a longitudinal section of a conventional typical gas chromatograph oven.
[0003]
The oven is a box surrounded by four walls 12 on the top, bottom, left, and right sides, a back wall 16 and a door 15 serving as a front wall, and a column (not shown) is placed in a tank chamber 20 that occupies most of the internal space. ), The fan 14 is rotated by a motor 17 provided outside the tank, and the air heated by the energized heater 13 is circulated to heat the inside of the tank as uniformly as possible. Since the surrounding walls 12, 15, 16 all have a heat insulating structure and the internal space is thermally insulated from the outside, the internal temperature can be kept at a maximum of about 450 ° C.
[0004]
The fan 14 is a radial fan, and the air flow sent out radially in a direction perpendicular to the rotation axis is heated while passing through the gap of the heater 13 arranged so as to surround the outer periphery of the fan, thereby forming a shade-shaped guide. It is guided forward by the plate 22, circulates through the forward tank chamber 20, passes through a net-like guard 23 provided on the front surface of the fan 14, and circulates along the route returning to the fan 14. In addition, the arrow in a figure shows the outline of such an airflow.
[0005]
The back wall 16 has an exhaust port 32 and an intake port 33 that can be opened and closed by an exhaust door 36 and an intake door 37, respectively. The partition wall 24 made of a metal plate partitions the back surface and the upper space of the fan 14 from the tank chamber 20, and the exhaust path 31 leading from the tank chamber 20 to the exhaust port 32, and the intake air extending from the intake port 33 to the back surface of the fan 14. A path 34 is formed. The intake passage 34 is connected to the tank chamber 20 through an opening 30 (also serving as a through-hole of the rotating shaft of the fan 14) provided at a position facing the back surface of the fan 14 on the partition wall 24. Further, the exhaust path 31 and the intake path 34 are separated by a partition wall 25 extending from the partition wall 24 to the back wall 16.
[0006]
When the oven temperature is controlled to about 70 ° C. or higher (high temperature range) in the oven configured as described above, both the doors 36 and 37 are closed, and the energization power of the heater 13 is appropriately controlled by a temperature controller (not shown). While controlling, the fan 14 keeps the tank room temperature at a predetermined temperature by creating a circulating air flow in the tank room 20 as described above.
[0007]
When the temperature is controlled from about 40 ° C. to about 70 ° C. (medium temperature range), opening / closing control of the doors 36 and 37 is added thereto. That is, when the temperature in the tank is slightly higher than a predetermined value, the energized power of the heater 13 is reduced, and the doors 36 and 37 are appropriately opened by an opening / closing mechanism including a motor (not shown), so that the air intake 33 Outside air at room temperature is sucked into the fan 14 and introduced into the tank through the intake path 34 and the opening 30, and at the same time, part of the heated air in the tank chamber 20 is discharged from the exhaust path 31 to the exhaust port 32. It is discharged out of the tank. When the temperature in the tank is thus lowered to a predetermined value, both doors 36 and 37 are closed, and when the temperature is further lowered, the electric power of the heater 13 is increased to raise the temperature. By repeating such an operation, temperature control in the middle temperature range is performed.
[0008]
When the inside of the tank is cooled after the control of the temperature range from room temperature to about 40 ° C (near room temperature range) or the analysis at a high temperature, both doors 36 and 37 are fully opened, and the outside air is always kept in the tank. While being distributed, temperature control is performed by adjusting the power of the heater 13. Further, in a temperature range below room temperature (low temperature range), the temperature can be controlled by closing both doors 36 and 37 and introducing a refrigerant such as liquefied nitrogen into the tank. Thus, the oven in the gas chromatograph can control the temperature in the tank in the range of about −100 ° C. to 450 ° C.
[0009]
In the example of FIG. 1, the doors 36 and 37 are configured to be linked by a link mechanism (not shown). An example of simplifying the opening and closing mechanism by omitting the link mechanism by installing the door hinge axis vertically, or by arranging two doors on the hinge axis installed horizontally by arranging the exhaust port and the intake port on the left and right Is also seen.
[0010]
[Problems to be solved by the invention]
In the above-described conventional oven, a fan having an air blowing capacity sufficient to perform near-room temperature control or to sufficiently ventilate the tank during cooling is used. However, in the high temperature range where ventilation is not required, the fan has an excessively large blowing capacity, causing the following adverse effects.
[0011]
That is, the pressure rises in the tank chamber 20 or the exhaust passage 31 from which the air flow is strongly sent out from the fan 14, and conversely, the suction passage 34 is sucked by the fan 14 and is in a reduced pressure state. For this reason, the problem that the air in a tank leaks out from the clearance gap between doors, the circumference | surroundings of piping (not shown) which penetrates a side wall, or the outside air leaks arises. This causes an unexpectedly large heat loss particularly in a temperature range of 300 ° C. or higher, which lowers the rate of temperature increase and restricts the maximum temperature that can be reached.
[0012]
The same applies to the case of controlling the temperature below room temperature (low temperature range).
[0013]
Further, closing both the doors 36 and 37 forcibly stops the air flow that should be created by the fan 14, but this causes the motor 17 to be placed in a half-stall state, thereby increasing heat generation and reducing power loss. Not only does this increase, there is also concern about the durability of the motor.
[0014]
Further, if the fan 14 has an excessive blowing capacity even in the middle temperature range, for example, even when the exhaust and intake doors 36 and 37 are slightly opened and a small amount of outside air is taken in, the suction force of the fan 14 is strong. There is a problem that a large amount of outside air is inhaled and the temperature in the tank is suddenly lowered, and temperature control by door opening / closing control becomes difficult.
[0015]
Thus, in the conventional gas chromatograph oven, the capability required of the fan differs depending on the temperature range. As a countermeasure, there is an example in which a variable speed motor is already used as the fan motor 17 and the air blowing capacity is switched according to the temperature range. However, this method increases the cost of the variable speed motor or its speed control circuit. Has the disadvantage of inviting.
[0016]
In consideration of such problems, the present invention provides an oven that can control a wide temperature range from a high temperature range to a low temperature range with the same fan blowing capacity, and has excellent temperature controllability and low heat loss. It is for the purpose.
[0017]
[Means for Solving the Problems]
In order to achieve the above object, in the oven for gas chromatography of the present invention, in addition to the oven having the conventional structure as shown in FIG. 1, an air passage extending from the exhaust passage to the intake passage is provided, and at the mouth of the air passage , It is those provided door to automatically open and close by the wind pressure of the air flow created by the fan, whereby even when the door of the exhaust port and the intake port is closed, the vessel chamber from the fan, the exhaust passage, an intake passage Since there is a circulation path outside the tank chamber that returns to the fan through the air, there is no local pressure difference in the internal space of the oven, and there is less leakage of warm air and leakage of outside air, which is highly energy efficient. An oven with excellent temperature control performance over a wide temperature range can be realized at a cost that is almost the same as conventional ones.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 2 shows an embodiment of the present invention in a form that can be easily compared with the conventional example of FIG. In FIG. 2, the same components as those in FIG.
[0019]
2 is different from FIG. 1 in the intake / exhaust doors 36 and 37 and their surroundings. That is, the intake / exhaust doors 36 and 37 on the back wall 16 are formed in the form of revolving doors provided at mutually symmetrical positions on the same hinge axis, and air passages that pass from the exhaust passage 31 to the intake passage 34. The air passage 26 is opened on the partition wall 25. When the exhaust door 36 opens to the outside, the intake door 37 opens to the inside, and the intake door 37 is disposed so as to close the air passage 26 when the exhaust door 36 is in a substantially horizontal position (fully open).
[0020]
In the oven configured as described above, when temperature control in a high temperature range is performed, the intake / exhaust doors 36 and 37 are closed in a vertical position, and thus the air passage 26 is open. As described above, a circulating air flow is generated in the tank chamber 20, but the fan 14 has a sufficient blowing capacity just by creating this circulating air flow in the tank chamber, and further, the exhaust path 31, the ventilation path 26, and the intake path from the tank chamber 20. 34, the circulation air flow outside the tank returns to the fan 14 through the opening 30 of the partition wall 24, and as a result, the pressure difference that has been locally generated in the conventional tank is released, and the leakage of warm air and the leakage of outside air are reduced. Heat loss is also suppressed, and it is possible to raise the temperature in a high temperature range without difficulty. Further, the problem that an excessive load is applied to the motor 17 is also solved.
[0021]
In the middle temperature range, the temperature is controlled by adjusting the power of the heater while opening and closing the intake / exhaust doors 36 and 37 to an appropriate opening degree. The remaining air flows through the ventilation path 26 to the intake path 34, joins the outside air flowing in from the intake port 33, and is sucked from the opening 30 of the partition wall 24 to the back surface of the fan 14. In this case, since an appropriate amount of air is discharged or sucked according to the opening of the door, the problem of disturbing the temperature control by introducing a large amount of air at a small opening as in the past is It will be resolved.
[0022]
During near room temperature control or cooling, the intake / exhaust doors 36 and 37 are in a horizontal position and are fully open, and the air passage 26 is closed. This is the near room temperature control or cooling in a conventional oven. It is completely the same as the time.
[0023]
Moreover, in the low temperature range below room temperature, similarly to the case of the high temperature range where both doors are fully closed, heat (cooling) loss is reduced and energy efficiency is improved.
[0024]
As described above, the oven according to the present invention has the same or better performance in terms of controllability and heat loss than conventional ovens in each temperature range. A good energy-saving oven with low energy loss can be obtained.
[0025]
Note that the fan 14 is not limited to the illustrated radial fan, and even in the case of an axial fan that blows air toward the front (or rear) of the fan in parallel with the shaft, the arrangement of the heaters and the like are appropriately changed in consideration of the direction of air flow. Then, the present invention can be applied. Regarding the other parts, the specific structure can be variously modified within the scope of the present invention.
[0026]
In addition, it is not a requirement of the present invention that the intake / exhaust doors 36 and 37 are of the rotary type as shown in FIG. 2, and the exhaust door, the intake door, and the vent door are provided separately, respectively. The effects are the same even if they are linked and linked with each other. In this case, only the door of the vent hole 26 can be configured to be automatically opened and closed by wind pressure without depending on the link mechanism.
[0027]
FIG. 3 shows such a modified embodiment.
[0028]
Also in FIG. 3, the same components as those shown in FIG. The ventilation path from the exhaust path 31 to the intake path 34 is formed by providing an opening 26 and a door 35 for opening and closing the partition wall 24 using the space behind the guide plate 22. The door 35 is installed so as to hang down with the hinge up, and normally the opening 26 of the air passage is closed by its own weight. When both the exhaust and intake doors 36 and 37 are closed (high temperature region or low temperature region), the door 35 is opened by the wind pressure of the air flow created by the fan 14, and a circulation airflow outside the tank chamber is generated. Further, when the doors 36 and 37 are fully opened (near room temperature range or during cooling), the air flow (air flow from the exhaust path 31 to the exhaust port 32) deviates from the door 35, so that the door 35 receives wind pressure. It closes by its own weight. When both doors 36 and 37 are half-opened due to temperature control in the middle temperature range, a part of the exhaust flow is directed to the ventilation passage according to the opening degree, and some wind pressure is applied to the door 35. Open moderately. As described above, in the example of FIG. 3, the interlocking mechanism is not particularly provided in the door 35, but the door 35 operates almost the same as the example of FIG. 2. The advantage of the configuration as shown in FIG. 3 is that the degree of freedom in design such as the position of the air passage is large. It should be noted that the door 35 can be closed by a spring having an appropriate strength in addition to the door 35 closed by its own weight.
[0029]
【The invention's effect】
Since the present invention is configured as described in detail above, the temperature control performance is improved in a wide range from the low temperature range to the high temperature range, and the energy efficiency is particularly improved in the high temperature range where the energy consumption rate is high. In addition, a large energy saving effect can be obtained.
[Brief description of the drawings]
FIG. 1 is a sectional view showing an example of a conventional gas chromatograph oven.
FIG. 2 is a sectional view showing an embodiment of a gas chromatograph oven according to the present invention.
FIG. 3 is a sectional view showing another embodiment of the gas chromatograph oven according to the present invention.
[Explanation of symbols]
12 ... Side wall 13 ... Heater 14 ... Fan 15 ... Front wall (door)
16 …… Back wall 17 …… Motor 20 …… Vacuum chamber 22 …… Guide plate 23 …… Guards 24, 25 …… Partition wall 26 …… Ventilation passage 31 …… Exhaust passage 32 …… Exhaust port 33 …… Intake port 34 …… Intake channel 35 …… Vent door 36 …… Exhaust door 37 …… Intake door

Claims (1)

  A box formed by four side walls, a front door, and a rear wall, a heater for heating a tank inside the tank, a fan for circulating the tank air, and the tank air An exhaust port for exhausting outside, an exhaust path for introducing air from the tank chamber to the exhaust port, an intake port for introducing outside air into the tank, and an intake path for guiding air from the intake port to the back of the fan; In the air bath type thermostatic chamber provided with a mechanism for opening and closing the exhaust port and the intake port, the exhaust path and the intake path generated by the action of the fan in a ventilation path between the exhaust path and the intake path A gas chromatograph oven characterized in that it is provided with a door that opens and closes due to a difference in pressure between the pressure and the pressure.

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