JPH055060B2 - - Google Patents

Description

Detailed Description of the Invention (Technical field to which the invention pertains) The present invention relates to a column oven for a gas chromatograph, and in particular to a column oven for a gas chromatograph used when the column temperature is raised from a low temperature to a high temperature at a constant rate to separate a sample. It concerns column ovens.

(Prior art) When separating the components of a mixture with a wide boiling point range such as crude oil, if the column is operated at an appropriate column temperature to separate the low boiling point components in the sample, the retention capacity for the high boiling point components will be very small. It becomes large and it is not possible to obtain a sharp waveform. On the other hand, if the column is operated at an appropriate column temperature for the separation of high-boiling components, the low-boiling components will not be sufficiently separated and will flow out very quickly. Therefore, the column temperature in the column oven is initially set to a low temperature in order to separate low-boiling components, and after the sample is injected into the sample vaporization chamber, the power given to the heater in the column oven is controlled to maintain a constant temperature. The method used is to raise the temperature at a rapid rate and sequentially separate components from low boiling point components to high boiling point components. To set the column temperature for separating low-boiling components, liquid carbonic acid or the like is usually injected into the column oven, and the heat of vaporization lowers the temperature. When the liquid carbon dioxide injected into the column oven vaporizes, it becomes carbon dioxide gas and is discharged through the shaft hole of the fan motor installed inside the column oven and the gap in the casing, but it does not look good from the outside. Furthermore, when the column oven is being cooled by injection of liquid carbon dioxide, it is affected by the temperature from the heating block that includes the sample vaporization chamber and detector located in the column oven. The disadvantages were that the cooling efficiency was poor and the amount of liquid carbonate consumed was large.

(Object of the Invention) The present invention solves the drawbacks of the prior art described above, and includes providing a flow passage on the side of the heating block that includes the sample vaporization chamber and the detector in the column oven.
An exhaust path is provided to exhaust the gas in the column oven to the outside, and an exhaust valve is provided to communicate or shut off the communication path with the exhaust path.By opening and closing the exhaust valve, a part of the gas in the column oven is released into the circulation path. An object of the present invention is to provide a column oven for a gas calomatograph that can exhaust gas to the outside through an exhaust passage or circulate a part of the gas inside the column oven through its circulation passage.

(Structure of the Invention) The present invention provides an exhaust valve located between an exhaust path penetrating to the outside of the column oven and a flow path formed by the lower surface of the heating block and the partition plate, according to the temperature of the column oven. When the exhaust valve is open, part of the gas in the column oven is discharged to the outside through the circulation passage and exhaust passage, and when the exhaust valve is closed, the exhaust passage is shut off and the circulation passage is connected to the column. By creating a circulation path for some of the gas in the oven,
This increases cooling efficiency and heating efficiency, and also has the effect of eliminating the boundary between the heating block and column oven.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of a column oven for a gas chromatograph according to the present invention will be described below with reference to the drawings.

(Example) (Figures 1 to 4) Figure 1 shows a side sectional view of an example of a column oven for a gas chromatograph of the present invention.

In the figure, C is a casing surrounding the column oven and its attached equipment. 1 is a sample vaporization chamber into which a carrier gas and a sample are injected, and the sample is vaporized. 2 is a detector which quantitatively detects the components separated and sent out from the column; for example, a thermoconductive type detector is used. 3 is a heating block in which a sample vaporization chamber 1 and a detector 2 are disposed. This heating block 3 is constantly heated to a temperature of 400° C. by a heating device (not shown) when analyzing samples containing high boiling point components such as crude oil.
4 is a column oven, which is surrounded by a heat insulating section S made of a heat insulating material. 5 is a column,
The inlet side of the column 5 is connected to the sample vaporization chamber 1, and the outlet side thereof is connected to the detector 2. 6 is a column oven door. 7 is a motor provided outside the column oven 4, and 8 is a fan, both of which are axially coupled. This fan 8 is rotationally driven by a motor 7 to circulate heated gas within the column oven 4 to maintain a uniform temperature inside the column oven 4. A heater 9 is made of a heating wire such as a nichrome wire and is connected to a temperature control device (not shown), which controls the heating power applied to the heater 9 to raise the temperature of the column oven 4 at a constant rate. go. 10 is a liquid carbonic acid injection nozzle, and 11 is a liquid carbonic acid control electromagnetic valve, both of which are connected.The liquid carbonic acid control electromagnetic valve 11 is connected to a liquid carbonic acid container (not shown). The liquid carbonic acid control solenoid valve 11 is connected to a temperature control device (not shown) via a lead wire, and upon receiving a control signal from the temperature control device (not shown), the solenoid valve 11 is opened.
A predetermined amount of liquid carbonic acid is injected into the column oven 4 from the liquid carbonic acid injection nozzle 10, and the column oven 4 is brought to a low temperature by the heat of vaporization. Reference numeral 12 denotes a temperature control sensor that detects the temperature inside the column oven 4 and applies its detection signal to a temperature control device (not shown). 13 is an exhaust valve, and 13' is its pivot point.
P is an exhaust path for exhausting gas in the column oven 4 to the outside via the casing C. Reference numeral 16 denotes a partition plate, which is disposed opposite to the lower surface of the upper heat insulating section Su in which the heating block 3 is buried, with a gap in between, and has a distribution passage 1 for a part of the gas in the column oven 4.
form 7. A part of the gas in the column oven 4 passes through the circulation passage 17 from the upper part of the column oven door 6, and when the exhaust valve 13 is open to the exhaust passage P, it directly communicates with the outside through the exhaust passage P. When the exhaust valve 13 is closed to the exhaust path P, the heater 9 located at the rear of the column oven 4
Form a circulation flow path to the side. The aforementioned exhaust valve 13
is open in a temperature range from the temperature at the time of liquid carbon dioxide injection to approximately 60°C, and the exhaust passage P and the circulation passage 17
The column oven 4 is connected by the fan 8.
A part of the gas circulated inside is discharged to the outside via the circulation passage 17 and the exhaust passage P. When the temperature of column oven 4 reaches approximately 60°C or higher, exhaust valve 1
3 is rotated counterclockwise around the pivot point 13' to cut off communication between the exhaust passage P and the circulation passage 17, forming the circulation passage 17 as a circulation passage for part of the gas in the column oven 4. A part of the gas being circulated within the column oven 4 by the fan 8 is caused to flow into the heater 9 side via the circulation passage 17. 1
4 is a protective wire mesh for the fan 8 and the heater 9, 1
Reference numeral 5 denotes a gas rectification guide plate that guides the gas sent by the fan 8 and passing around the column oven 4 to the heater 9.

FIG. 2 is a graph showing temperature changes in the column oven 4, with the horizontal axis representing heating time and the vertical axis representing heating temperature.

In the same figure, a predetermined amount of liquid carbonic acid is injected from the liquid carbonic acid injection nozzle 10 into the column oven 4 at the point , and the temperature inside the column oven 4 is lowered by the heat of vaporization, resulting in a constant low temperature state at the point . At this point, a sample is injected into the sample vaporization chamber 1, and heating power is applied to the heater 9 in a controlled manner to raise the temperature at a constant rate. At a temperature of approximately 60° C., the exhaust valve 13 rotates counterclockwise around its pivot point 13' to block the exhaust path P and allow the flow path 17 to pass through a portion of the gas in the column oven 4. Create a circulation flow path. Heating power is applied to the heater 9 while being controlled, and the temperature continues to rise at a constant rate. At point , a constant heating power is applied to the heater 9 to maintain the inside of the column oven 4 at a constant temperature until point . The sample injected into the sample vaporization chamber 1 passes through the column 5 between the points
It is separated into each component by Thereafter, the temperature inside the column oven 4 is lowered in preparation for the next analysis. Note that the line indicated by indicates the temperature of the heating block 3 in which the sample vaporization chamber 1 and the detector 2 are installed.

Figure 3 shows the exhaust valve 13 remaining open until the temperature reaches approximately 60°C from the temperature at the time of liquid carbon dioxide injection, and Figure 4 shows the state in which the exhaust valve 13 remains open from the temperature at the time of liquid carbon dioxide injection until the temperature reaches approximately 350°C. With the exhaust valve 13 closed,
A side sectional view of the main parts of the column oven is shown.

In FIG. 3, the exhaust valve 13 is open, and the circulation passage 17 and the exhaust passage P are in communication. The gas sent by fan 8 passes through column 5;
A portion of the gas rising upward in the vicinity of the column oven door 6 passes through the circulation passage 17 and is discharged to the outside via the exhaust passage P. In FIG. 4, the exhaust valve 13 rotates counterclockwise about the pivot point 13' to cut off communication with the exhaust path P and transform the circulation path 17 into a circulation flow path for part of the gas in the column oven 4. shall be. The gas sent by the fan 8 passes through the column 5, and a part of the gas rising upward near the column oven door 6 passes through the circulation passage 17 and passes through the gas rectification guide plate 15.
is sent to a heater 9 located at the rear of the vehicle.

The operation of the embodiment shown in FIG. 1 will be explained with reference to FIGS. 2 to 4.

Before injecting the sample into the sample vaporization chamber 1, the column oven 4 detected by the temperature control sensor 12
The temperature signal within is applied to a temperature control device (not shown).
The exhaust valve 13 is opened by a control signal from this temperature control device (not shown), the motor 7 is driven to rotate and the fan 8 is rotated, and the liquid carbonic acid control solenoid valve 11 is opened to inject a predetermined amount of liquid carbonic acid. The liquid is injected from the nozzle 10, and then the solenoid valve 11 is closed. The injected liquid carbonic acid is vaporized, and the temperature inside the column oven 4 is lowered by the heat of vaporization. When a predetermined low temperature is reached, the sample is injected into the sample vaporization chamber 1 at point 2 in FIG. 2, and heating power is applied to the heater 9 while controlling it. The temperature control sensor 12 detects the temperature inside the column oven 4 and applies it to a temperature control device (not shown). The heater 9 to which heating power is applied is controlled by the temperature control device (not shown), and the column oven 4 is heated at a constant speed.
The temperature is increased. Since the exhaust valve 13 is open, the exhaust passage P and the circulation passage 17 are in communication as shown in FIG. Therefore, the low-temperature gas sent by the fan 8 passes through the column 5, and a part of the low-temperature gas rising upward near the column oven door 6 passes through the circulation passage 17 and is discharged to the outside via the exhaust passage P. be done. The low-temperature gas passing through the circulation passage 17 absorbs heat generated from the upper heat insulation section Su in which the heating block 3 facing the circulation passage 17 is buried, and the sample vaporization chamber 1 and the detector 2 exposed in the circulation passage 17. Discharge outside. Heating block 3 as mentioned above.
is constantly heated at a temperature of 400℃, and the heat transfer,
Due to the radiation effect, the temperature of the upper heat insulating section Su is approximately 200°C and the temperature of the partition plate 16 is approximately 60°C, but since the above-mentioned generated heat is discharged to the outside, the influence of heat on the column oven 4 at low temperatures is reduced. This results in the advantage that the cooling efficiency can be increased and the consumption of liquid carbon dioxide can be reduced. Heating power is applied to the heater 9 in a controlled manner to raise the temperature at a constant rate, and when the column oven temperature reaches approximately 60°C, the temperature control sensor 12 detects this temperature, and the detection signal is used for temperature control (not shown). Add to device. A control signal is given to the exhaust valve 13 from a temperature control device (not shown), and as shown in FIG. The communication is cut off, and the circulation passage 17 becomes a circulation passage for a part of the gas in the column oven 4. The gas sent by the fan 8 passes through the column 5, and part of the gas rising upward near the column oven door 6 passes through the circulation passage 17.
Heater 9 located at the rear of the gas rectification guide plate 15
sent to. By forming this circulation flow path, heat generated from the upper heat insulating section Su in which the heating block 3 is buried facing the flow path 17 and the sample vaporization chamber 1 and the detector 2 exposed in the flow path 17 is transferred to the column oven 4.
This makes it possible to increase the efficiency of temperature rise within the column oven 4 and eliminate the delay in temperature rise at the boundary between the column and the heating block.

In addition to the cooling method using liquid carbon dioxide injection, the column oven temperature can be controlled even at temperatures near room temperature by using a method for feeding cooling air from a separate cooler or room temperature air. The range can be expanded.

Furthermore, the same effect can be obtained by using liquid nitrogen instead of liquid carbon dioxide as the cooling medium.

(Effects of the Invention) As explained above, according to the present invention, a distribution passageway through which a part of the air in the column oven circulates is formed by an upper insulating section in which a heating block having a sample vaporization chamber and a detector is buried, and a partition plate. An exhaust valve is provided between this circulation passage and an exhaust passage opening outside the column oven, and after the column oven is cooled by a cooling device, the exhaust valve is opened until a predetermined temperature is reached. When a predetermined column oven temperature is reached, the exhaust valve is closed to cut off the communication between the exhaust passage and the circulation passage, and the circulation passage is used as a circulation passage for part of the gas in the column oven. Because of this configuration, the column oven temperature is kept low and until the predetermined column oven temperature is reached, the heat generated from the sample vaporization chamber 1 and the detector 2 exposed in the upper insulation part and the circulation path is transferred to the exhaust path. The column oven can be opened and discharged to the outside, thus reducing the effect of heat on the column oven at low temperatures, thereby increasing cooling efficiency and reducing the consumption of refrigerant ejected from the cooling device. be able to. After the column oven temperature reaches a predetermined temperature, the heat generated from the upper insulating part facing the circulation passage, the sample vaporization chamber exposed in the circulation passage, and the detector is transferred to the column by the gas circulating through the circulation passage. By feeding the column into an oven and raising the temperature, it is possible to eliminate the delay in raising the temperature of the column.

[Brief explanation of the drawing]

1 to 4 show an embodiment of a column oven for a gas chromatograph of the present invention, FIG. 1 is a side sectional view thereof, FIG. 2 is a graph showing the temperature rise of the column oven, and FIGS. The figure shows a side sectional view of the main parts of the column oven when the exhaust valve is open and closed. In the figure, 1 is a sample vaporization chamber, 2 is a detector, 3 is a heating block, 4 is a column oven, 5 is a column, and 7
is a motor, 8 is a fan, 9 is a heater, 10 is a liquid carbon dioxide injection nozzle, 11 is a solenoid valve for controlling liquid carbon dioxide,
13 is an exhaust valve, 16 is a partition plate, 17 is a circulation passage,
P indicates an exhaust path.

Claims (1)

[Claims] 1. A circulation passage formed by a partition plate arranged at a gap on the lower surface of the heating block, an exhaust passage provided through the rear part of the column oven and communicating with the outside, and a communication passage with the exhaust passage. a gas chromatograph column oven, comprising: an exhaust valve disposed between the exhaust passage and the flow passage, the exhaust valve being able to connect or shut off the exhaust passage and the circulation passage depending on the temperature of the column oven.