Elemental analysis device, elemental analysis method, and elemental analysis program

Abstract

The present invention comprises: a gas-component-retaining unit 6 that is provided in a lead-out flow path L2 and retains components other than hydrogen for a longer period than hydrogen among the components contained in a lead-out gas; a temperature adjustment unit 7 that adjusts the temperature of the gas-component-retaining unit 6; and a detection unit 8 that is provided further downstream than the gas-component-retaining unit 6 in the lead-out flow path L2 and detects a component that has passed through the gas-component-retaining unit 6. The set temperature of the temperature adjustment unit 7 can be changed.

Description

Elemental Analyzer, Elemental Analysis Method, and Elemental Analysis Program 【0001】 The present invention relates to an elemental analyzer, an elemental analysis method, and an elemental analysis program. 【0002】 Conventionally, there is an elemental analyzer that analyzes hydrogen contained in a sample by heating the sample contained in a crucible in a heating furnace while introducing a carrier gas and analyzing the gas generated at that time. 【0003】 In this type of elemental analyzer, for example, as shown in Patent Document 1, in a gas analysis line through which the gas derived from the heating furnace flows, a dust filter, an oxidizer, a CO2 remover, and a detector are provided in this order from the upstream side. In the above elemental analyzer, the gas derived from the heating furnace passes through the dust filter, the oxidizer, and the CO2 remover, so that the main component detected by the detector becomes hydrogen, and the concentration of hydrogen contained in the sample is calculated. 【0004】 Japanese Patent Application Laid-Open No. 2005-227045 【0005】 By the way, in the above elemental analyzer, in order to accurately analyze hydrogen contained in a sample, a molecular sieve may be provided, for example, in the gas analysis line between the CO2 remover and the detector. The molecular sieve retains components other than hydrogen longer than hydrogen among the gases that have passed through the CO2 remover. As a result, hydrogen passes through the molecular sieve earlier than components other than hydrogen, so the detector detects hydrogen earlier than components other than hydrogen. 【0006】 However, there are cases where hydrogen and components other than hydrogen cannot be well separated in the molecular sieve, and the components detected earlier by the detector may include components other than hydrogen. Therefore, in the above elemental analyzer, there is room for further improving the analysis accuracy of hydrogen contained in the sample. 【0007】 Therefore, the present invention has been made in view of the above problems, and the main problem is to separate the gas into hydrogen and components other than hydrogen before the gas derived from the heating furnace is introduced into the detector, and improve the analysis accuracy of hydrogen contained in the sample. 【0008】 The inventors of this invention, after diligently studying to solve the above problems, first noticed that while the waveform of components other than hydrogen obtained from the detection unit changes depending on the temperature controlling the molecular sieve, the waveform of hydrogen does not change. The inventors then discovered that by changing the set temperature of the temperature control unit that controls the molecular sieve, the gas in the molecular sieve can be successfully separated into hydrogen and components other than hydrogen, and thus conceived the present invention. 【0009】 In other words, the elemental analyzer of the present invention comprises a heating furnace that generates a sample gas by heating a sample placed in a crucible while introducing a carrier gas; an outlet channel that discharges an outlet gas composed of the sample gas and the carrier gas from the heating furnace; a gas component holding section provided in the outlet channel that holds components other than hydrogen for a longer period of time than hydrogen among the components contained in the outlet gas; a temperature control section that controls the temperature of the gas component holding section; and a detection section provided downstream of the gas component holding section in the outlet channel that detects components that have passed through the gas component holding section, wherein the set temperature of the temperature control section can be changed. 【0010】 With this elemental analyzer, the temperature setting of the temperature control unit for regulating the gas component holding unit can be changed. By changing the setting temperature to a temperature below a predetermined level, hydrogen and other components are separated in the gas component holding unit. As a result, the detection unit can accurately detect the hydrogen contained in the hydrogen gas. Furthermore, by changing the setting temperature so that the detection unit accurately detects hydrogen and other components are quickly released from the gas component holding unit to the detection unit, it is possible to suppress the length of measurement time from when the released gas is generated until the other components pass through the detection unit. 【0011】A thermal conduction detector (hereinafter also referred to as TCD) can detect hydrogen with high accuracy compared to other detectors, such as non-dispersive infrared absorption detectors (hereinafter also referred to as NDIR), but it cannot selectively detect different types of components. Therefore, in order to analyze hydrogen contained in a sample with high accuracy using a TCD, it is necessary to effectively separate the discharged gas into hydrogen and non-hydrogen components in the gas component holding section. For this reason, it is preferable that the detection unit be a thermal conduction detector that detects components contained in the discharged gas regardless of the type of components contained in the discharged gas. With this configuration, by changing the set temperature of the temperature control section, the discharged gas is separated into hydrogen and non-hydrogen components in the gas component holding section, so that hydrogen contained in the sample can be detected with high accuracy using a TCD. 【0012】 The system further includes a control unit that controls the temperature control unit based on the set temperature, wherein the set temperature has a first set temperature that allows hydrogen to pass through the gas component holding unit before other components, and a second set temperature that is higher than the first set temperature and allows other components to pass through the gas component holding unit, and the control unit controls the temperature control unit based on the first set temperature and then controls the temperature control unit based on the second set temperature. 【0013】 In this configuration, the temperature control unit first controls the temperature control unit based on the first set temperature, allowing hydrogen to pass through the gas component holding unit first, and enabling the detection unit to detect hydrogen with high accuracy. On the other hand, if the control unit continues to control based on the first set temperature, components other than hydrogen will be released from the gas component holding unit later, resulting in a longer measurement time for components other than hydrogen to be released from the gas component holding unit to the detection unit. Also, if the first set temperature is low, it puts a strain on the temperature control unit. Therefore, the control unit controls the temperature control unit based on the first set temperature, and then controls it based on the second set temperature, thereby preventing the measurement time from becoming unnecessarily long and reducing the burden on the temperature control unit. 【0014】The switching trigger for the control unit to switch from the first set temperature to the second set temperature may be a predetermined time elapsed since the start of control at the first set temperature, or a predetermined value of the hydrogen concentration detected by the detection unit. With this configuration, the control unit switches the set temperature based on the switching trigger, allowing the detection unit to accurately detect hydrogen and enabling components other than hydrogen to be quickly released from the gas component holding unit to the detection unit. 【0015】 One example is a configuration that further includes a carrier gas adjustment unit for adjusting the flow rate or velocity of the carrier gas. With this configuration, if the discharged gas is not properly separated from hydrogen and other components, increasing the flow rate or velocity of the carrier gas can further separate the hydrogen from the other components. 【0016】 The gas component holding section includes a first gas component holding section provided in the outlet channel and a second gas component holding section provided downstream of the first gas component holding section in the outlet channel. With this configuration, since the first gas component holding section and the second gas component holding section are provided in series, hydrogen gas and components other than hydrogen can be further separated compared to the case where there is only one gas component holding section. 【0017】 The discharge channel further comprises a branch channel that branches off from between the first gas component holding section and the second gas component holding section and connects to the downstream side of the second gas component holding section, a switching valve that switches the flow path of the discharged gas between the branch channel and the discharge channel where the second gas component holding section is provided, and a switching valve control unit that controls the switching valve, wherein after hydrogen has been discharged from the second gas component holding section, the flow path of components other than hydrogen is switched from the discharge channel where the second gas component holding section is provided to the branch channel. With this configuration, after hydrogen has been discharged from the second gas component holding section, components other than hydrogen can be discharged from the gas component holding section more quickly. 【0018】As time passes, the gas component holding section retains the components of the discharged gas for a shorter period of time, and temperature control alone is insufficient to restore the retention time of the gas component holding section. Therefore, one example of an elemental analyzer is one that further includes a heating section, which is provided around the gas component holding section and heats the gas component holding section separately from the temperature control section. With this configuration, the heating section is a separate component from the temperature control section and is provided around the gas component holding section for heating, so the retention time of the gas component holding section can be restored without removing the gas component holding section from the discharge channel. As a result, the effort required of the user and the analytical errors caused by removing the gas component holding section from the discharge channel can be reduced. 【0019】 The elemental analysis method is characterized by using an elemental analyzer comprising: a heating furnace that generates a sample gas by heating a sample placed in a crucible while introducing a carrier gas; an outlet channel that discharges an outlet gas composed of the sample gas and the carrier gas from the heating furnace; a gas component holding section provided in the outlet channel that holds components other than hydrogen for a longer period of time than hydrogen among the components contained in the outlet gas; a temperature control section that controls the temperature of the gas component holding section; and a detection section provided downstream of the gas component holding section in the outlet channel that detects components that have passed through the gas component holding section, and changing the set temperature of the temperature control section. The elemental analysis program is used in an elemental analyzer comprising: a heating furnace that generates a sample gas by heating a sample placed in a crucible while introducing a carrier gas; an outlet channel that discharges an outlet gas composed of the sample gas and the carrier gas from the heating furnace; a gas component holding unit provided in the outlet channel that holds components other than hydrogen for a longer period of time than hydrogen among the components contained in the outlet gas; a temperature control unit that controls the temperature of the gas component holding unit; and a detection unit provided downstream of the gas component holding unit in the outlet channel that detects components that have passed through the gas component holding unit, wherein the set temperature of the temperature control unit can be changed, and the computer performs the function of a control unit that controls the temperature control unit based on the set temperature. 【0020】With this configuration, the same effects and benefits as the elemental analyzer described above can be obtained. 【0021】 According to the present invention, the gas discharged from the heating furnace can be separated into hydrogen and non-hydrogen components before being introduced into the detection unit, thereby improving the accuracy of hydrogen analysis in the sample. 【0022】 A schematic diagram of an elemental analyzer in one embodiment of the present invention. A graph showing the time change in the concentration of the component detected by the detection unit in the same embodiment. A flowchart showing the elemental analysis method in the same embodiment. A schematic diagram of an elemental analyzer in another embodiment of the present invention. A schematic diagram of an elemental analyzer in another embodiment of the present invention. 【0023】 The elemental analyzer according to one embodiment of the present invention will be described below with reference to the drawings. Note that, for the sake of clarity, the following drawings may be simplified or exaggerated for illustrative purposes. The same reference numerals are used for identical components, and their descriptions will be omitted as appropriate. 【0024】 <Device Configuration> The elemental analyzer 100 of this embodiment analyzes hydrogen contained in a sample by heating the sample placed in a crucible R and extracting the sample gas generated at that time. In this embodiment, the elemental analyzer 100 analyzes only hydrogen contained in the sample and does not have a detection unit to detect other components such as carbon monoxide, carbon dioxide, or water. 【0025】 Specifically, as shown in Figure 1, the elemental analyzer 100 includes a heating furnace 2 that heats a sample placed in a crucible R to generate a sample gas, a carrier gas introduction channel L1 that introduces a carrier gas into the heating furnace 2, and an outlet channel L2 that discharges the output gas, which consists of the sample gas and carrier gas, from the heating furnace 2. The configuration of each part will be described below. 【0026】One end of the carrier gas introduction channel L1 is connected to the heating furnace 2, and the other end is connected to a carrier gas supply source 1, such as a gas cylinder. In this embodiment, a gas with a high specific heat among inert gases, such as Ar gas, is introduced from the supply source 1 into the carrier gas introduction channel L1. 【0027】 The heating furnace 2 holds the crucible R containing the sample between a pair of electrodes and heats the crucible R and the sample by directly passing an electric current through the crucible R while introducing a carrier gas. The sample gas generated by heating the sample contains, in addition to hydrogen, which is the element to be analyzed, for example, carbon monoxide (CO) gas or nitrogen (N) gas. ２ ) Contains gases, etc. 【0028】 As shown in Figure 1, the outlet channel L2 is equipped with a dust filter 3, an oxidizer 4, a removal mechanism 5, a gas component holding unit 6, and a detection unit 8, all arranged in series from upstream to downstream. The gas component holding unit 6 is temperature-controlled by a temperature control unit 7. The following describes each component provided in the outlet channel L2. 【0029】 The dust filter 3 filters out dust, such as soot, contained in the discharged gas, thereby removing it. 【0030】 The oxidizer 4 oxidizes carbon monoxide contained in the discharged gas that has passed through the dust filter 3 to carbon dioxide, and is an oxidation catalyst such as copper oxide. 【0031】 The removal mechanism 5 removes carbon dioxide from the discharged gas that has passed through the oxidizer 4, such as a reagent. 【0032】 The gas component holding section 6 is designed to retain components other than hydrogen in the discharged gas for a longer period than hydrogen. Specifically, the gas component holding section 6 is made of materials such as molecular sieves, which are less adsorbent of hydrogen and more adsorbent of components other than hydrogen. As a result, hydrogen is discharged from the gas component holding section 6 before the other components. 【0033】The temperature control unit 7 controls the temperature of the gas component holding unit 6, and is, for example, a Peltier element. The temperature control unit 7 controls the temperature of the gas component holding unit 6 so that its temperature reaches the set temperature, under the control of the control unit C2, which will be described later. 【0034】 The detection unit 8 detects the components that have passed through the gas component holding unit 6. Specifically, the detection unit 8 is a thermal conduction type detector (TCD) that detects components contained in the output gas regardless of the type of components contained in the output gas. The detection unit 8 outputs a measurement signal indicating the concentration of the components that have passed through the gas component holding unit 6 to the hydrogen concentration calculation unit C1 and / or a general-purpose display D, which will be described later. 【0035】 Here, as shown in Figure 1, the elemental analyzer 100 further includes an arithmetic control unit C, which is a so-called computer equipped with, for example, a CPU, memory, A / D converter, D / A converter, and various input / output means. The arithmetic control unit C performs at least the functions of a hydrogen concentration calculation unit C1 and a control unit C2 through the execution of a program stored in memory and the cooperation of various devices. In this embodiment, the hydrogen concentration calculation unit C1 and the control unit C2 perform their functions on the same computer, but they may perform their functions on separate computers. 【0036】 The hydrogen concentration calculation unit C1 acquires a measurement signal from the detection unit 8 and calculates the hydrogen concentration contained in the sample based on that measurement signal. Specifically, as shown in Figure 2, the hydrogen concentration calculation unit C1 uses the waveform that shows the time change in the concentration of the components obtained from the detection unit 8, specifically the waveform that shows the time change in hydrogen concentration from when the concentration first rises, through the peak value, and then to zero, as the waveform that shows the time change in hydrogen concentration, and calculates the hydrogen concentration based on that waveform. The hydrogen concentration calculation unit C1 may also output the hydrogen concentration to a general-purpose display D. 【0037】 The control unit C2 controls the temperature control unit 7 based on the set temperature of the temperature control unit 7. Specifically, the control unit C2 receives a set temperature input from the user or a set temperature stored in the device in advance, and controls the temperature control unit 7 so that it outputs a current corresponding to that set temperature. 【0038】In this embodiment, the set temperature can be changed according to the waveform showing the time change in the concentration of the components obtained from the detection unit 8. By changing the set temperature, the time it takes for components other than hydrogen to pass through the gas component holding unit 6 changes according to the change in the set temperature. Specifically, the higher the set temperature, the faster the components are released from the gas component holding unit 6, and the lower the set temperature, the slower the components are released from the gas component holding unit 6. Therefore, as shown in Figure 2, the waveform showing the time change in the concentration of components other than hydrogen changes depending on the set temperature. 【0039】 In contrast, the time it takes for hydrogen to pass through the gas component holding section 6 hardly changes with changes in the set temperature. Therefore, as shown in Figure 2, the waveform showing the time change of hydrogen concentration hardly changes with high or low set temperatures. 【0040】 More specifically, as shown in Figure 2, when we examine the waveforms showing the time change in the concentration of the components obtained by the detection unit 8 at different set temperatures T1, T2, and T3 (where T1 > T2 > T3), in the waveform at set temperature T1 (dashed line in Figure 2), a point t1 occurs where the concentration of components other than hydrogen rises before the concentration of hydrogen reaches zero. As a result, the waveform in which the concentration rises first, passes through its peak value, and then reaches zero contains both hydrogen and components other than hydrogen, so the hydrogen concentration calculation unit C1 cannot accurately calculate the concentration of hydrogen contained in the sample. 【0041】 On the other hand, in the waveform at the set temperature T2 (solid line in Figure 2), after the point t21 in which the hydrogen concentration drops from its peak value to zero, there is a point t22 in which the concentration of components other than hydrogen rises from zero. Similarly, in the waveform at the set temperature T3 (dotted line in Figure 2), after the point t31 in which the hydrogen concentration drops from its peak value to zero, there is a point t32 in which the concentration of components other than hydrogen rises from zero. As a result, at set temperatures T2 and T3, the waveform in which the concentration first rises, then passes through the peak value and drops to zero, shows a change in the concentration of hydrogen only, so the hydrogen concentration calculation unit C1 can accurately calculate the concentration of hydrogen contained in the sample. 【0042】However, at the set temperature T3, compared with the set temperature T2, the time between the point when the hydrogen concentration becomes 0 from the peak value and the point when the concentration of components other than hydrogen starts to rise from 0 becomes longer, and the waveform showing the time change of the concentration of components other than hydrogen becomes a broader waveform. As a result, compared with the time t23 when the components other than hydrogen at the set temperature T2 finish passing through the detection unit 8, the time t33 when the components other than hydrogen at the set temperature T3 finish passing through the detection unit 8 becomes later, and the measurement time becomes longer. 【0043】 <Elemental analysis method> Next, an elemental analysis method using the elemental analyzer 100 of the present embodiment will be described while referring to FIG. 3. 【0044】 First, the set temperature of the temperature control unit 7 is set (S1). 【0045】 Next, the crucible R containing the sample is placed in the heating furnace 2, and while introducing a carrier gas into the heating furnace 2, the crucible R and the sample are heated. Thereby, a sample gas is generated in the heating furnace 2, and a derived gas composed of the sample gas and the carrier gas is derived from the heating furnace 2. The derived gas passes through the dust filter 3, the oxidizer 4, the removal mechanism 5, and the gas component holding unit 6 in this order. The detection unit 8 detects the components that have passed through the gas component holding unit 6 (S2). 【0046】 Next, based on the waveform shown by the measurement signal from the detection unit 8, it is confirmed whether the derived gas is separated into hydrogen and components other than hydrogen in the gas component holding unit 6 (S3). Here, that the derived gas is separated into hydrogen and components other than hydrogen means that after a predetermined time has elapsed from the point when the concentration first rises from 0, passes through the peak value, and becomes 0, the next point when the concentration rises has occurred. 【0047】 If the next point when the concentration rises occurs between the time when the concentration first rises from 0, passes through the peak value, and becomes 0, it is determined that the derived gas is not separated into hydrogen and components other than hydrogen in the gas component holding unit 6. In this case, the set temperature is changed to a temperature lower than the set temperature set in S1 (S4). Then, the process returns to S2. 【0048】If the concentration rises from zero again after a predetermined time has elapsed since the initial rise from zero, through a peak value, and then back to zero, the gas component holding unit 6 determines that the discharged gas has been separated into hydrogen and other components. In this case, it is determined whether the measurement time is within the predetermined time (S5). 【0049】 Specifically, the system determines whether the time from the start of measurement to the point when the concentration finally becomes zero is within a predetermined time. If this time is within the predetermined time, the set temperature set in S1 is deemed appropriate, and the same set temperature is used for the next analysis. If no further analysis is performed, the elemental analysis may be terminated. 【0050】 On the other hand, if the time from the start of measurement to the point when the concentration finally becomes 0 is longer than a predetermined time, the set temperature is changed to a higher temperature than the set temperature set in S1 (S6). Then, the process returns to S2. 【0051】 <Effects of this embodiment> According to the elemental analyzer 100 of this embodiment, since the set temperature of the temperature control unit 7 can be changed, if the discharged gas is not separated into hydrogen and other components in the gas component holding unit 6, the set temperature can be changed to a temperature below a predetermined temperature, thereby separating the hydrogen and other components in the gas component holding unit 6. As a result, the detection unit 8 can accurately detect the hydrogen contained in the hydrogen gas. Furthermore, if the measurement time at the set temperature is longer than a predetermined time, the measurement time from when the discharged gas is generated until the components other than hydrogen pass through the detection unit 8 can be increased by changing the set temperature to a higher temperature. 【0052】 <Other Embodiments> The present invention is not limited to the embodiments described above. 【0053】In the above embodiment, the set temperature was not changed in one analysis, but was changed in the next analysis. However, the set temperature may be changed in a single analysis. Specifically, the set temperature has a first set temperature that allows hydrogen to pass through the gas component holding unit 6 before other components, and a second set temperature that is higher than the first set temperature and allows components other than hydrogen to pass through the gas component holding unit 6. The control unit C2 may first control the temperature control unit 7 based on the first set temperature, and then control the temperature control unit 7 based on the second set temperature. 【0054】 In a single analysis, the control unit C2 first controls the temperature control unit 7 based on the first set temperature, so that hydrogen is released from the gas component holding unit 6 before other components. As a result, the detection unit 8 can detect hydrogen with high accuracy. 【0055】 After hydrogen is released from the gas component holding unit 6, the control unit C2 switches the set temperature from the first set temperature to the second set temperature, causing the gas component holding unit 6 to reach a temperature higher than the first set temperature. As a result, components other than hydrogen are released from the gas component holding unit 6 more quickly compared to when the control unit C2 controls the temperature control unit 7 based on the first set temperature. In addition, since the temperature control unit 7 is set to a temperature higher than the first set temperature, the load on the temperature control unit 7 is also reduced. 【0056】 Here, the switching trigger for the control unit C2 to switch from the first set temperature to the second set temperature is either a predetermined time elapsed since the start of control at the first set temperature, or a predetermined value of the hydrogen concentration detected by the detection unit 8. Specifically, the predetermined value of the hydrogen concentration is, for example, the peak value of the hydrogen concentration, or a predetermined percentage of the peak value of the hydrogen concentration. 【0057】 In addition to changing the set temperature in the above embodiment, the elemental analyzer 100 may further include a carrier gas adjustment unit C3 for adjusting the flow rate or velocity of the carrier gas, as shown in Figure 4, for example. In this case, the carrier gas adjustment unit C3 adjusts the flow rate or velocity of the carrier gas according to the waveform showing the time change in the concentration of the components obtained from the detection unit 8. 【0058】Specifically, in the first analysis, the carrier gas is flowed at a predetermined flow rate or velocity, and the detection unit 8 detects the components that have passed through the gas component holding unit 6. Then, based on the waveform showing the time change in the concentration of the components obtained from the detection unit 8, it is confirmed whether the discharged gas has been separated into hydrogen and other components in the gas component holding unit 6. If the discharged gas has not been separated into hydrogen and other components in the gas component holding unit 6, the flow rate or velocity setting is reduced in the second and subsequent analyses. On the other hand, if the measurement time is longer than the predetermined time, the flow rate or velocity setting is increased in the second and subsequent analyses. 【0059】 In addition to changing the set temperature in the above embodiment, the gas component holding section 6 may also have, for example, as shown in Figure 5, a first gas component holding section 61 provided in the outlet channel L2 and a second gas component holding section 62 provided downstream of the first gas component holding section 61 in the outlet channel L2. With this configuration, hydrogen gas and components other than hydrogen can be further separated compared to the case where there is only one molecular sieve constituting the gas component holding section 6. Note that the gas component holding section 6 may also have three or more molecular sieves. 【0060】 Furthermore, as shown in Figure 5, the elemental analyzer 100 may include a branch channel L3 that branches off from between the first gas component holding section 61 and the second gas component holding section 62 in the outlet channel L2 and connects to the downstream side of the second gas component holding section 62, a switching valve V that switches the flow path of the outlet gas between the branch channel L3 and the outlet channel L2 where the second gas component holding section 62 is provided, and a switching valve control unit C4 that controls the switching valve V. The switching valve V is, for example, a three-way valve and is configured to select either that the components that have passed through the first gas component holding section 61 are introduced to the detection section 8 through the second gas component holding section 62, or that they are introduced to the detection section 8 through the branch channel L3 without passing through the second gas component holding section 62. 【0061】Specifically, the switching valve control unit C4 switches the flow path of the discharged gas between the branched flow path L3 and the discharged flow path L2, which is equipped with the second gas component holding unit 62, depending on the type of sample. More specifically, if the sample is difficult to separate into hydrogen and non-hydrogen components, the switching valve control unit C4 sets the flow path of the discharged gas to the discharged flow path L2, which is equipped with the second gas component holding unit 62. If the sample is easily separated into hydrogen and non-hydrogen components, the switching valve control unit C4 sets the flow path of the discharged gas to the branched flow path L3. With this configuration, the discharged gas can be separated into hydrogen and non-hydrogen components depending on the type of sample, so that hydrogen contained in various types of samples can be analyzed with high accuracy. 【0062】 Furthermore, the switching valve control unit C4 is not limited to switching the flow path for components other than hydrogen during a single analysis. For example, in the first analysis, the flow path for components other than hydrogen may be set to the outlet flow path L2 or branch flow path L3, which is provided with the second gas component holding unit 62. Then, in subsequent analyses, the switching valve control unit C4 may switch the flow path for components other than hydrogen based on the waveform showing the time change in the concentration of the components obtained from the detection unit 8 in the first analysis. 【0063】 In the above embodiment, since the time that the gas component holding unit 6 holds the components of the discharged gas decreases over time, a heating unit (not shown) may be further provided around the gas component holding unit 6 to heat the gas component holding unit 6 in order to restore the time that the gas component holding unit 6 holds the components of the discharged gas. The heating unit is a separate component from the temperature control unit 7 and can heat to a higher temperature than the temperature control unit 7, for example, an electric heating element. The heating unit may be attached around the gas component holding unit 6 and covered with, for example, an insulating material. 【0064】 In this configuration, the heating unit is a separate component from the temperature control unit 7 and is provided around the gas component holding unit 6 for heating. Therefore, the time for the gas component holding unit 6 to hold the components of the discharged gas can be restored without removing the gas component holding unit 6 from the discharge channel L2. As a result, the effort required of the user and the analytical errors caused by removing the gas component holding unit 6 from the discharge channel L2 can be reduced. 【0065】 Furthermore, the present invention can be modified in various ways, as long as it does not contradict its spirit. 【0066】 According to the present invention, the gas discharged from the heating furnace can be separated into hydrogen and non-hydrogen components before being introduced into the detection unit, thereby improving the accuracy of hydrogen analysis in the sample. 【0067】 100... Elemental analyzer 2... Heating furnace 3... Dust filter 4... Oxidizer 5... Removal mechanism 6... Gas component holding unit 61... First gas component holding unit 62... Second gas component holding unit 7... Temperature control unit 8... Detection unit C... Calculation control unit C1... Hydrogen concentration calculation unit C2... Control unit C3... Carrier gas adjustment unit C4... Switching valve control unit L1... Carrier gas introduction channel L2... Outlet channel L3... Branch channel V... Switching valve T1, T2, T3... Set temperature

Claims

1. An elemental analyzer comprising: a heating furnace that generates a sample gas by heating a sample placed in a crucible while introducing a carrier gas; an outlet channel for discharging an outlet gas composed of the sample gas and the carrier gas from the heating furnace; a gas component holding section provided in the outlet channel that holds components other than hydrogen for a longer period than hydrogen among the components contained in the outlet gas; a temperature control section that controls the temperature of the gas component holding section; and a detection section provided downstream of the gas component holding section in the outlet channel for detecting components that have passed through the gas component holding section, wherein the set temperature of the temperature control section is changeable.

2. The elemental analyzer according to claim 1, wherein the detection unit is a thermal conduction type detector that detects components contained in the discharged gas regardless of the type of components contained in the discharged gas.

3. The elemental analyzer according to claim 1 or 2, further comprising a control unit that controls the temperature control unit based on the set temperature, wherein the set temperature has a first set temperature that allows hydrogen to pass through the gas component holding unit before other components, and a second set temperature that is higher than the first set temperature and allows other components to pass through the gas component holding unit, and the control unit controls the temperature control unit based on the first set temperature and then controls the temperature control unit based on the second set temperature.

4. The elemental analyzer according to claim 3, wherein the switching trigger for the control unit to switch from the first set temperature to the second set temperature is a predetermined time elapsed since the start of control by the first set temperature, or a predetermined value of the hydrogen concentration detected by the detection unit.

5. The elemental analyzer according to any one of claims 1 to 4, further comprising a carrier gas adjustment unit for adjusting the flow rate or flow velocity of the carrier gas.

6. The elemental analyzer according to any one of claims 1 to 5, wherein the gas component holding section comprises a first gas component holding section provided in the outlet channel and a second gas component holding section provided downstream of the first gas component holding section in the outlet channel.

7. The elemental analyzer according to claim 6, further comprising: a branch channel in the discharge channel that branches off from between the first gas component holding section and the second gas component holding section and connects to the downstream side of the second gas component holding section; a switching valve that switches the channel through which the discharge gas flows between the branch channel and the discharge channel provided with the second gas component holding section; and a switching valve control unit that controls the switching valve, wherein the switching valve control unit switches the channel through which the discharge gas flows between the discharge channel provided with the second gas component holding section and the branch channel according to the type of sample.

8. The elemental analyzer according to any one of claims 1 to 7, further comprising a heating unit provided around the gas component holding unit and heating the gas component holding unit separately from the temperature control unit.

9. An elemental analysis method using an elemental analyzer comprising: a heating furnace that generates a sample gas by heating a sample placed in a crucible while introducing a carrier gas; an outlet channel for discharging an outlet gas composed of the sample gas and the carrier gas from the heating furnace; a gas component holding section provided in the outlet channel that holds components other than hydrogen for a longer period of time than hydrogen among the components contained in the outlet gas; a temperature control section that controls the temperature of the gas component holding section; and a detection section provided downstream of the gas component holding section in the outlet channel for detecting components that have passed through the gas component holding section, wherein the set temperature of the temperature control section is changed.

10. An elemental analysis program for use in an elemental analyzer comprising: a heating furnace that generates a sample gas by heating a sample placed in a crucible while introducing a carrier gas; an outlet channel for discharging an outlet gas composed of the sample gas and the carrier gas from the heating furnace; a gas component holding unit provided in the outlet channel that holds components other than hydrogen for a longer period of time than hydrogen among the components contained in the outlet gas; a temperature control unit that controls the temperature of the gas component holding unit; and a detection unit provided downstream of the gas component holding unit in the outlet channel for detecting components that have passed through the gas component holding unit, wherein the set temperature of the temperature control unit is changeable, and the computer performs the function of a control unit that controls the temperature control unit based on the set temperature.

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