JPH09145644A - Analyzer having detecting element such that temperature adjustment is required - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an analyzer, which can stably operate a detecting element without using heat insulating material. SOLUTION: Temperatures TH and TL in the vicinity of a Peltier element 2h and in the vicinity of the detecting part of a photomultiplier 2e are measured with a first temperature sensor 2f and a second temperature sensor 2g. A target temperature TLd in the vicinity of the Peltier element 2h is determined by the following expression TLd=TL+(THd-TH) by using the temperatures TH and TL measured with S1 and the target temperature THd in the vicinity of the detecting part of the photomultiplier 2e. When the target temperature TLd in the vicinity of the Peltier element 2h is determined, the current, which is supplied to the Peltier element 2h, is controlled so that the temperature TL measured with the first temperature sensor 2f becomes the determined target temperature TLd. When the temperature TL measured with the first temperature sensor 2f becomes the determined target temperature TLd, the step is returned to S1, and the operations of above described S1-S3 are repeatedly performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an analyzer having a detection element which requires temperature control, and more particularly to a chemiluminescence type nitrogen oxide analyzer.

[0002]

2. Description of the Related Art As a typical analyzer having a detection element that requires temperature control, there is, for example, a chemiluminescence type nitrogen oxide analyzer. Such a chemiluminescent nitrogen oxide analyzer is a nitrogen oxide (NOx) that is harmful to the human body due to combustion in a combustion furnace of a factory or combustion in an engine of an automobile.
) Is a device for measuring the concentration of a gas to be measured (a sample collected from the atmosphere, an exhaust gas, etc.) and ozone (O3) gas are brought into contact with each other in a reaction tank of the measuring device, and nitric oxide ( The amount of nitric oxide contained in the gas to be measured is quantitatively measured by detecting the light generated when NO) and ozone chemically react with each other with a photodetector.

FIG. 4 is a schematic view showing a reaction part of a conventional chemiluminescence type nitrogen oxide meter and a detection part for detecting light generated in the reaction part. That is, in FIG.
In a, the light generated when the ozone (O3) gas and the nitric oxide (NO) in the gas to be measured cause a chemical reaction is emitted from the photomultiplier 20e through the light transmission window 20c.
Is detected by Photomultiplier 20e is A
It is covered with a block 20d having a good thermal conductivity such as 1 or Cu, and the cooling side of a Peltier element 20h which is a cooling means is attached to this block 20d. And
The entire block 20d is covered with a heat insulating material 20b so that its temperature is constant, and the cooling fins 20 attached to the heat generating side of the Peltier element 20h outside the heat insulating material 20b.
h'is provided and the heat is dissipated by the fan 20j.

Further, the Peltier element 20 of the block 20d
A temperature sensor 20f is incorporated in the vicinity of h, and the temperature control means 20k controls the temperature measured by the temperature sensor 20f to a desired temperature for the stable operation of the photomultiplier 20e.

[0005]

However, in the conventional structure in which the block 20d for temperature adjustment is covered with the heat insulating material 20b as a heat insulating material in this way, the whole analyzer becomes large in size and the apparatus cannot be made compact. . In addition, moisture in the atmosphere enters the gap between the heat insulating material 20b, which is a heat insulating material, and the block 20d, which causes dew condensation on the surface of the block, causing moisture to enter the Peltier element and damage it.

On the other hand, when a heat insulating material is not used, a temperature difference occurs between the cooling element of the photomultiplier 20e, which is a detection element, and the vicinity of the actual photodetection section due to the ambient temperature. The photomultiplier 20 is installed near the Peltier device 2h.
Therefore, the temperature in the vicinity of the photodetector of e cannot be controlled to a desired temperature. Further, it is conceivable to attach the temperature sensor 20f in the vicinity of the photodetector of the photomultiplier 20e, but since the distance from the Peltier element 2h is large, a large ripple occurs during temperature control, and stable temperature control is achieved. Can not.

Therefore, the present invention was devised to solve such problems, and an object thereof is to provide an analyzer capable of stably operating a detection element without using a heat insulating material.

[0008]

In order to achieve the above object, an analyzer according to the present invention having a detection element which requires temperature adjustment, detects a physical quantity and heats or cools this detection element. A temperature adjustment element, a first temperature sensor that measures the temperature near the cooling element of the detection element, a second temperature sensor that measures the temperature near the physical quantity detection unit of the detection element, and a physical quantity detection of the detection element. Part temperature, the temperature measured by the second temperature sensor, and the first temperature
From the temperature measured by the temperature sensor, the target temperature in the vicinity of the cooling element of the detection element is determined, and the temperature adjustment element is set so that the temperature obtained by the first temperature sensor becomes the determined target temperature. And a temperature control unit for controlling the temperature.

The detection element is covered with a block made of a material having high thermal conductivity, and the first temperature sensor and the second temperature sensor are incorporated in this block. The entire block is hermetically sealed in a hermetic container, and the hermetic container is filled with dry gas.

The temperature control means determines the difference between the target temperature in the vicinity of the physical quantity detecting portion of the detecting element and the temperature measured by the second temperature sensor and the temperature measured by the first temperature sensor. A target temperature near the cooling element of the detection element may be determined, and the temperature adjustment element may be controlled so that the temperature obtained by the first temperature sensor becomes the determined target temperature.

Further, the temperature control means sets the difference between the target temperature in the vicinity of the physical quantity detecting portion of the detecting element and the temperature measured by the second temperature sensor and the temperature measured by the first temperature sensor. The sum may be determined as a target temperature near the cooling element of the detection element, and the temperature adjustment element may be controlled so that the temperature obtained by the first temperature sensor becomes the determined target temperature. .

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will now be described with reference to FIGS.
This will be described with reference to FIG.

FIG. 1 shows an overall schematic view of a chemiluminescence nitrogen oxide analyzer, which is a typical analyzer having a detection element which requires temperature control. In the figure, a flow path line 3 is provided between a gas introduction part 1 for introducing a gas to be measured and a reaction cell 2 integrally connected with a photoelectric detection part (not shown) (illustrated in FIG. 2). . A converter 4, which converts nitrogen dioxide into NO, a pretreatment unit 5, and a flow rate control unit 6 are connected to the flow path line 3. On the other hand, an ozone gas supply line 11 for supplying ozone gas from the ozone generation unit 9 is connected to the reaction cell 2 by piping. Further, the reaction cell 2 is connected to an ozone decomposer 12 for decomposing ozone in exhaust gas and an indicator 12 for indicating the detected NO gas concentration.

In the chemiluminescence type nitrogen oxide analyzer having the above structure, the NO 2 gas and N
The gas to be measured coexisting with O gas is N provided with a reduction catalyst.
NO2 is converted into NO by passing through the O2-NO converter 4, and the NO concentration in the gas is detected in the reaction cell 2. On the other hand, by detecting the NO concentration in the measured gas without passing it through the NO2-NO converter 4,
The NO2 gas concentration is calculated from the difference between the NO gas concentrations.

FIG. 2 is a detailed view of the reaction cell 2, in which the light generated when the ozone (O3) gas and the nitric oxide (NO) in the gas to be measured cause a chemical reaction in the reaction tank 2a. , Is detected by the photomultiplier 2e through the light transmission window 2c formed in the closed container 2b. The photomultiplier 2e is covered with a block 2d having a high thermal conductivity such as Al or Cu, and is arranged in a closed container 2b filled with dry gas. The block 2d has a Peltier element as a cooling means. The cooling side of 2h is attached. A cooling fin 2h ′ attached to the heat generating side of the Peltier element 2h is provided outside the closed container 2b,
The heat is dissipated by the fan 2j.

A first temperature sensor 2f is incorporated in the vicinity of the Peltier element 2h of the block 2d, and a second temperature sensor 2g is incorporated in the vicinity of the light detecting portion of the photomultiplier 2e of the block 2d. ing. Then, the temperature control means 2k inputs the measurement signals of both the temperature sensors 2f and 2g, and controls the Peltier element 2h so that the vicinity of the photodetector of the photomultiplier 2e of the block 2d becomes a desired temperature.

FIG. 3 is a flow chart showing the operation of the temperature control means 2k. First, the photomultiplier 2e from the first temperature sensor 2f and the second temperature sensor 2g.
Near Peltier device 2h and photomultiplier 2e
The temperatures TL and TH near the photodetector are measured (S1).
The temperatures TL and TH to be measured here can be measured more accurately by using the average value of the detection values obtained by the respective temperature sensors within a fixed time.

Next, the target temperature T near the Peltier element 2h
Using the temperatures TL and TH obtained by measuring Ld in S1 and the target temperature THd in the vicinity of the photodetector of the photomultiplier 2e, it is determined by the following equation TLd = TL + (THd-TH) (S2).

When the target temperature TLd near the Peltier element 2h is determined, the temperature T measured by the first temperature sensor 2f
The current supplied to the Peltier element 2h is controlled so that L becomes the determined target temperature TLd (S3). And
When the temperature TL measured by the first temperature sensor 2f reaches the determined target temperature TLd, the process returns to S1 and S1 to S1 described above are performed.
The operation of S3 is repeated.

As described above, the target temperature THd in the vicinity of the light detecting portion of the photomultiplier 2e, which is the detecting element, and the temperature measured by the second temperature sensor 2g provided in the vicinity of the light detecting portion of the photomultiplier 2e, Is added to the temperature measured by the first temperature sensor 2f provided in the vicinity of the Peltier element 2h of the photomultiplier 2e, and this is set as the target temperature TLd in the vicinity of the cooling element of the detection element. Since the Peltier element 2h is controlled so that the temperature obtained in 2f becomes the determined target temperature TLd, the actual temperature control is performed in the vicinity of the Peltier element 2h of the photomultiplier 2e with less ripples, and the photomultiplier is used. If the vicinity of the Peltier element 2h of the plier 2e approaches the determined target temperature TLd, the vicinity of the photodetector of the photomultiplier 2e will also change. It is believed to be Nozomu of the target temperature THd.

As described above, according to the present invention, since the actual temperature control is performed in the vicinity of the cooling element of the detecting element having a small ripple, stable temperature control is performed with a small amount of ripple, and the vicinity of the physical quantity detecting portion of the detecting element is maintained. It becomes possible to control to a desired target temperature. Further, in the present invention, since the vicinity of the physical quantity detection part of the detection element can be set to a desired target temperature without using a heat insulating material, the entire analyzer can be made compact,
Moreover, the problem of dew condensation can be solved, and the device can be constructed at low cost.

In the above-mentioned embodiment, the chemiluminescence type nitrogen oxide analyzer is shown as the analyzer having the detection element which needs the temperature adjustment, but the present invention is not limited to this, and the temperature adjustment is required. It can be applied to all analyzers having a detection element.

[0023]

According to the present invention, the actual temperature control is performed in the vicinity of the cooling element of the detecting element having a small ripple, and the target temperature in the vicinity of the cooling element of the detecting element is desired to be in the vicinity of the physical quantity detecting section of the detecting element. Since the target temperature is determined to be, the stable temperature control with less ripple can be performed, and the desired target temperature can be set in the vicinity of the physical quantity detection unit of the detection element.

Further, since the desired target temperature can be set in the vicinity of the physical quantity detecting portion of the detecting element without using a heat insulating material, the analyzer as a whole can be made compact and the problem of dew condensation can be solved and the device can be constructed at low cost. .

[Brief description of the drawings]

FIG. 1 is an overall schematic view of a chemiluminescent nitrogen oxide meter.

FIG. 2 is a diagram showing a reaction cell of a chemiluminescence type nitrogen oxide meter which is an embodiment of the present invention.

FIG. 3 is a flowchart showing the operation of temperature control means.

FIG. 4 is a view showing a reaction cell of a conventional chemiluminescence type nitrogen oxide meter.

[Explanation of symbols]

 2a ... Reactor tank 2b ... Closed container 2c ... Transmission window 2d ... Block 2e ... Photomultiplier 2f ... First temperature Sensor 2g-Second temperature sensor 2h-Peltier element 2j-Fan 2k-Temperature control means

Claims (1)

[Claims] 1. A detecting element for detecting a physical quantity, a temperature adjusting element for heating or cooling the detecting element, a first temperature sensor for measuring a temperature in the vicinity of a cooling element of the detecting element, and a physical quantity of the detecting element. Second to measure the temperature near the detector
Of the temperature sensor, the target temperature in the vicinity of the physical quantity detection unit of the detection element, the temperature measured by the second temperature sensor, and the temperature measured by the first temperature sensor, the vicinity of the cooling element of the detection element And a temperature control means for controlling the temperature adjusting element so that the temperature obtained by the first temperature sensor becomes the determined target temperature. An analyzer with the necessary detection elements.