JPS585249Y2 - Gas chromatograph - Google Patents

Description

[Detailed description of the invention] This invention relates to the structure of a column oven for a gas chromatograph, particularly a small gas chromatograph that performs temperature-programmed analysis.

In general, column ovens (hereinafter referred to as ovens) for small gas chromatographs have parts that are used at temperatures higher than room temperature, such as the sample vaporization section and detection section, located adjacent to each other. temperature increases.

For this reason, when setting the column temperature to around room temperature, it has been conventional practice to draw outside air into the oven chamber or open the door of the oven chamber to lower the internal temperature.

However, these methods have disadvantages such as uneven temperature distribution within the oven chamber and insufficient shielding from the outside air, making it impossible to achieve satisfactory high-temperature characteristics.

This invention aims to realize a column oven for a gas chromatograph that eliminates these disadvantages, and one embodiment of this invention will be described in detail below.

FIG. 1 is an explanatory cross-sectional view of a column oven of a gas chromatograph according to an embodiment of this invention, in which 1 is a column, 2 is a sample vaporization section, 3 is a detection section, and the inside of the oven chamber 4 is constantly stirred by a fan 5. Ru.

5' is an electric motor that drives the fan 5, and 6 is a heater, which is controlled according to a temperature increase program.

Reference numeral 7 denotes an outside air intake passage which opens at a position where negative pressure is generated by the back pressure of the fan 5, and passage valves 9 and 9' are provided at the external openings of each of the outside air intake passage 7 and the ξ exhaust passage 8, respectively. be.

Reference numeral 10 denotes a side passage that directly connects to the oven chamber 4 from the middle of the suction passage 7, and is opened and closed by a side passage valve 11.

During the cooling period due to the temperature increase program, the bypass valve 11
In the closed state, both road valves 9, 9' are opened to circulate outside air through the oven chamber 4, and the oven chamber 4 is cooled to the room temperature at the location where the equipment is installed.

On the other hand, if the side valve 11 is open when the temperature of the oven chamber 4 gradually increases due to the influence of the temperature of the vaporization section 2 and the detection section 3 and the rise in the temperature of the heater 6, the fan 5 The air inside the oven chamber 4 is mixed with the outside air sent in from the side passage 10, and the air inside the oven chamber 4 is mixed with the air inside the oven chamber 4 as cold air is introduced.
Nonuniform temperature distribution is prevented.

Next, in order to raise the temperature further by temperature raising operation, both road valves 9, 9' or one of them is closed to block the inflow of outside air into the oven chamber 4.
After that, the mixture is circulated and stirred by the fan 5, and the temperature continues to rise.

At this time, due to the back pressure of the fan 5, the negative pressure applied to the passage valve 9 of the suction passage 7 is weakened by the side passage 10, preventing outside air from entering and further enhancing the high temperature characteristics of the oven.

Although the passage valves 9 and 9' may be provided only on either one,
When these valves are provided on both sides, one side may be biased normally closed using a weak spring or the like, and the valve may be self-biased and closed by the flow of air passing through the valve.

In this case, the other valve and the bypass valve 11 utilize electrically operated solenoid valves or the like.

These solenoid valves are opened and closed at predetermined temperatures by a temperature detector 12 provided in the oven chamber 4, thereby simplifying the operation of the oven.

Further, these valves can also be operated using command signals from a control program for the heater 7 instead of the temperature detector 12 described above.

FIG. 2 is a diagram of the temperature program for the oven chamber 4 in this invention, showing the relationship with valve operation, with the vertical axis representing oven temperature and the horizontal axis representing time.

S is the analysis start point, and A is the cooling period. During this period, the passage valves 9 and 9' are opened and the side passage valve 11 is closed.

B is the early stage of temperature rise, and when the temperature is below the predetermined temperature P, the passage valves 9, 9' and the side passage valve 11 are opened.

C is in the latter half of the temperature rise, and when the temperature is higher than the predetermined temperature 2, the passage valve 9 is closed.
, 9' are closed, and the bypass valve 11 is opened.

That is, during the cooling period A, the side channel 10 is closed and all outside air passes through the oven chamber 4 and enters the oven chamber 4 at maximum speed.
to cool down.

When the temperature is lower than the predetermined temperature P in the early stage of temperature rise B, the outside air is sent to the oven chamber 4, but the air inside the oven chamber 4 is mixed through the side passage 10 and circulated to the oven chamber 4 again, causing the temperature of the oven chamber 4 to decrease. Raise the temperature while maintaining uniform distribution.

When the temperature is higher than the predetermined temperature 2 in the latter half of the temperature rise 13, the inflow of outside air is blocked, and only circulation is performed through the side passage 10, and the temperature continues to rise while maintaining a uniform temperature distribution in the oven chamber.

At this time, the negative pressure applied to the passage valve 9 caused by the back pressure of the fan 5 is weakened by the circulating air flow in the side passage 10, and the intrusion of outside air is prevented.

As detailed above, this idea utilizes a fan that stirs the inside of the oven chamber to suck in outside air, and also provides a side passage that directly communicates with the oven chamber in the middle of this suction passage, allowing the outside air to flow into the oven chamber. is mixed with the air in the oven chamber in advance to equalize the excessive distribution inside the oven.Furthermore, even when raising the temperature by cutting off outside air, this side passage is used to ensure uniformity, and with the circulation through the side passage, By reducing the suction force of the fan against outside air, it is easier to block the suction passage, which provides excellent high temperature characteristics and efficient cooling.
It is possible to realize a gas chromatograph in a low-temperature range with excellent uniformity of temperature distribution and a gas chromatograph with excellent uniformity of temperature distribution and excellent high-temperature characteristics.

[Brief explanation of the drawing]

FIG. 1 is an explanatory cross-sectional view of a column oven of a gas chromatograph according to an embodiment of this invention, and FIG. 2 is a chart showing an example of an oven temperature program for explaining the operation of this invention. 1: Column, 2: Vaporization section, 3: Detection section, 4: Oven chamber, 5: Fan, 7: Outside air intake passage, 8: Exhaust passage, 9°9'... Passage valve, 10: Side Route, 11: Side route valve.

Claims (1)

[Scope of utility model registration request] In a gas chromatograph that has a column oven that is controlled according to a temperature increase program, there is a fan for stirring internal air, an outside air intake passage that opens to a negative pressure area due to the back pressure of the fan, and a passage that enters the oven chamber from the middle of this passage. It is characterized by comprising a direct side passage, a side passage valve that opens and closes this side passage, an exhaust passage that exhausts air in the oven chamber, and a passage valve that opens and closes each or one of these inner passages. gas chromatograph.