JPH085620A - Method and apparatus for analyzing combustion of plastic sample by gas chromatograph - Google Patents

Abstract

PURPOSE:To realize high concentration effect even for a combustion gas of quite low concentration by reproducing the combustion gas production data and to realize a high sensitivity analysis by introducing a sample with a narrow high concentration band width to chromatograph. CONSTITUTION:A ferromagnetic metal toil 6 wrapping a sample 5 is induction heated in a thermal decomposition/combustion chamber 10 and thermally decomposed to produce a gas. The gas is fired by means of an igniter 12 to produce a combustion gas which is carried on a combustion supporting gas through a thermally insulated pipe and absorbed by an adsorbent 1' filled in a primary adsorption tube 1. Upon finishing the combustion, a high purity purge gas is fed into the adsorption tube 1 in order to remove moisture and the combustion supporting gas from the adsorbent. The adsorption tube 1, in which only a target combustion gas is concentrated, is then transferred to a head space sampler 30 and heated by means of a heater 33. The combustion gas component 15 adsorbed by an adsorbent 2' filled in a secondary adsorption tube 2 held by the sampler 30. The adsorption tube 2 is then induction heated and the combustion gas is disorbed from the adsorbent 2 and introduced on a carrier gas to the capillary column 40 of gas chromatograph for the purpose of analysis.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is for analyzing gas generated when organic substances such as plastics are burned.
First, the sample is decomposed in the thermal decomposition process to generate a combustible gas, and then the combustion is performed to stabilize the gas generation condition and the combustion process accompanying it, and the generated combustion gas is adsorbed and released in two stages. TECHNICAL FIELD The present invention relates to a combustion analysis method for a plastic sample and a fuel analysis device, which are relatively favorably analyzed by a gas chromatograph by concentrating a small amount of an adsorbent to a high concentration in a secondary adsorption tube in the second stage.

[0002]

2. Description of the Related Art In a plastic combustion tester defined by JIS, a sample placed in a heating furnace self-combusts by spark ignition, and the gas generated by combustion is collected outside the system. To be done.

In the above-mentioned conventional example, the sample placed in the heating furnace is heated, and a spark spark ignites a gas component which is partially pyrolyzed and volatilized, and then ignites to generate a combustion gas. The organic gas generated by the fuel is collected in a nylon laminate bag.

[0004]

In the above conventional example, since the combustion process promotes the thermal decomposition following the gas generation due to the thermal decomposition, the thermal decomposition and the fuel process coexist.
The data obtained was not reproducible because the gas generation conditions varied greatly. Further, of the generated organic gas, a component having a large molecular weight was adsorbed on the inner surface of the nylon-based laminate bag for collection and could not be used for gas chromatograph analysis.

[0005]

The present invention was developed in order to solve the above-mentioned problems, and a method for combustion analysis of a plastic sample by a gas chromatograph according to the present invention is a liquid or solid sample of plastic. Is wrapped in a ferromagnetic metal foil for pyrolysis and stored in a combustion chamber, the ferromagnetic metal foil is inductively heated to pyrolyze the sample, and then pyrolysis gas is fed indoors while feeding combustion-supporting gas into the decomposition combustion chamber. The combustion gas is ignited to generate combustion gas, and the combustion gas is supplied to the primary adsorption pipe filled with a large amount of the adsorbent to be adsorbed by the adsorbent in the pipe, and after the adsorption, the inside of the primary adsorption pipe A combustion gas adsorbed by the adsorbent and a combustion gas adsorbed by the adsorbent are discharged to the outside of the tube to concentrate the combustion gas adsorbed by the adsorbent. , A small amount of adsorbent is filled inside, and A secondary adsorption tube wound with a ferromagnetic metal foil is held in a headspace sampler, the secondary adsorption tube is cooled, and the primary adsorption tube is heated to secondarily adsorb the combustion gas adsorbed by the adsorbent. When it is introduced into the tube, it is adsorbed by a small amount of adsorbent in the secondary adsorption tube, and after the adsorption, the ferromagnetic metal foil outside the secondary adsorption tube is induction-heated to volatilize the combustion gas adsorbed by the adsorbent The volatile gas is introduced into the gas chromatograph. Further, a combustion analysis apparatus for a plastic sample by a gas chromatograph of the present invention has a holding base for holding a ferromagnetic metal foil enclosing a plastic liquid or solid sample and an igniter inside, and encloses the sample. A high-frequency coil for inductively heating the ferromagnetic metal foil is wound outside, and the combustion gas and the purge gas are switched and fed into the interior. A primary adsorption tube detachably connected to the thermal decomposition and combustion chamber, a primary adsorption unit that detachably holds and cools the primary adsorption tube, and a small amount of an adsorbent is filled inside, The secondary adsorption tube having a ferromagnetic metal foil wound on the outside and the primary adsorption tube which can be heated and the secondary adsorption tube which can be cooled are respectively held, and the ferromagnetic metal foil outside the secondary adsorption tube is held. Equipped with a high-frequency coil for induction heating and a secondary adsorption tube 1
A headspace sampler equipped with a secondary adsorption tube and a switching valve that selectively communicates with the capillary column of the gas chromatograph.

[0006]

Embodiment In the illustrated embodiment, 1 is a primary adsorption tube, 2
Is a secondary adsorption tube, 10 is a pyrolysis and combustion chamber, 20 is a primary adsorption unit, and 30 is a headspace sampler. 1
The next adsorption tube 1 is a glass capillary having an inner diameter of 12 mm and a length of 120 mm, and a large amount, for example, 1000 mg of the adsorbent 1'is filled in the tube. The inner diameter of the secondary adsorption tube is 2.5.
A glass capillary having a length of 120 mm and a length of 120 mm is filled with a small amount of, for example, 40 mg of the adsorbent 2'in the tube, and a ferromagnetic metal foil 3 for heating the inside of the tube to the Curie point is wound around the outer periphery thereof. Adsorbent 1 filled in the adsorption tubes 1 and 2
′ And 2 ′ are selected and used depending on the type of gas phase component generated by the sample, and those which adsorb the gas phase component well,
For example, Tenax GC (AKZO Research
Laboratories) or the like can be used. Incidentally, in order to prevent the filled adsorbent from leaking to the outside in each adsorption tube, glass wool 4 is filled up and down.

The pyrolysis / combustion chamber 10 has a holding base 11 for holding a ferromagnetic metal foil 6 enclosing a liquid or solid plastic sample 5 and an igniter 12 such as an ignition heater, and the ferromagnetic A high frequency coil 13 for heating the metal foil 6 to the Curie point is wound outside. Then, from the lower end, air as a combustion-supporting gas and high-purity nitrogen gas that is a purge gas are switched by the switching valve 14 and fed into the chamber. In addition, the upper end is provided with a heat retaining pipe 15 which is kept warm by a heater. Ferromagnetic metal foil 3 wrapped around the outer circumference of the secondary adsorption tube,
The Curie point of the ferromagnetic metal foil 6 enclosing the sample 5 is a physical constant determined by the ratio of iron, nickel, cobalt, copper, etc. contained in the foil. For example, a Curie point of 235 ° C., a ferromagnetic metal having a small heat capacity of 50 μm. Foil (trade name Pyro foil: manufactured in-house) was used.

The primary adsorption unit 20 is constructed as a cooler 21 that surrounds the primary adsorption tube 1, and holds the primary adsorption tube inside the cooling device 21 in a penetrating manner. Liquid nitrogen is supplied into the cooler 21, which causes the primary adsorption tube to fall to -100 ° C.
Then, the adsorbent 1'is enhanced in adsorption capacity. The heat-retaining pipe 15 protruding from the upper end of the thermal decomposition / combustion chamber described above enters the primary adsorption pipe in an airtight manner from the lower end. This heat retaining pipe is for thermal decomposition and for preventing the combustion gas flowing from the combustion chamber 10 into the primary adsorption pipe from condensing in the pipe.

The headspace sampler 30 has the insertion recess 31 of the primary adsorption tube 1 and the ferromagnetic metal foil 3 wound around it.
The secondary suction pipe 2 is provided with an insertion recess 32 of the secondary suction pipe 2, and a heater for heating 33 is provided around the insertion recess 31 for the primary suction pipe, and the secondary suction pipe is placed at −100 ° C. around the insertion recess 32 for the secondary suction pipe. A cooler 34 for cooling and a high frequency coil 35 are provided outside the cooler 34. The coolers 21 and 34 described above may be of the type that circulates liquid nitrogen. A lid 36 for closing the upper end of the primary adsorption tube held in the insertion recess 31 of the headspace sampler 30.
A ventilation pipe 37 for supplying a purge gas is inserted into the pipe. Further, the head space sampler 30 has first flow paths 41, 2 communicating with the bottom opening of the insertion recess 31 of the primary adsorption tube 1.
The second flow path 42 communicating with the bottom opening of the insertion recess 32 of the next adsorption tube 2, the supply flow path 3 of the carrier gas such as helium gas
8, a gas discharge channel 39, an analysis channel 43 communicating with the gas chromatographic capital column 40, a communication channel opening at the upper end of the insertion recess 32 of the secondary adsorption tube and communicating with the upper end of the secondary adsorption tube 44, and a switching valve 5 for switching the flow path
0 is provided. The upper end of the insertion recess 32 of the secondary suction tube is closed by a removable lid 45. Incidentally, 47 is a high frequency power source for the high frequency coil 35, and 48 is a timer for controlling the induction heating time.

The valve body 50 'of the switching valve 50 is approximately 180
With the rotation of °, the valve body 50 'has a generally U-shaped valve passage,
At the first rotation position (FIG. 2) where the valve body is rotated 180 ° in one direction, the first valve path 51 penetrating the valve body in the diametrical direction causes the first
The flow path 41 and the second flow path 42 are connected to each other, and the arc-shaped third valve path 5 is formed.
3 connects the communication channel 44 and the gas discharge channel 39. At this time, the carrier gas supply passage 38 is formed by the second valve passage 52 perpendicular to the first valve passage and the arc-shaped fourth valve passage 54.
The analysis flow path 43 and the analysis flow path 43 are connected via an arc-shaped auxiliary flow path 46 provided in the headspace sampler, but they are not directly related to the present invention. Further, at the second rotation position (FIG. 3) in which the valve body 50 ′ is rotated 180 ° in the other direction, the carrier gas supply flow path 38 and the communication flow path 44 are connected by the second valve path 52, and the third valve The second flow path 42 and the analysis flow path 43 are connected by the path 53. At this time, the first passage 41 and the fourth passage 54 connect the first passage 41 and the gas discharge passage 39 via the auxiliary passage 46, but this is also not directly related to the present invention. In short, a total of eight openings to the two of the first, second, third and fourth valve passages are arranged at equal intervals in the circumferential direction on the outer periphery of the valve body 50 ', and the first and second flow passages are provided. , Six channels of carrier gas supply channel, gas exhaust channel, analysis channel, and communication channel, and
A total of eight openings of the two arc-shaped auxiliary flow paths are arranged in the head space sampler 30 at equal intervals in the circumferential direction so as to surround the valve body 50 '.

In order to perform the analysis, the primary adsorption tube is held in the primary adsorption unit 20, and the thermal decomposition pipe 15 of the pyrolysis / combustion chamber is connected to the lower end of the primary adsorption tube. Then, a ferromagnetic metal foil 5 enclosing a liquid or solid plastic sample 4 is attached to a holder 11 in the pyrolysis and combustion chamber, and a high frequency power is applied to a high frequency coil 13 from a high frequency power source. As a result, the ferromagnetic metal foil 5 has a Curie point (230
Since it is heated to (° C.), the sample wrapped in the coil is thermally decomposed and a thermally decomposed gas is generated.

When the pyrolysis is completed, the switching valve 14 is operated to ignite the pyrolysis gas with the ignition heater 12 while feeding air as a combustion-supporting gas into the primary adsorption pipe, and at the same time, the cooler of the primary adsorption unit. Liquid nitrogen is flown through 21 and the primary adsorption tube 1
Is cooled to −100 ° C. to enhance the adsorption capacity of the adsorbent 1 ′ in the tube. The pyrolysis gas becomes a combustion gas by ignition, and is a combustion-supporting gas that is sent into the room, flows into the primary adsorption pipe through the heat retaining pipe, and is adsorbed by the adsorbent 1'in the pipe. Adsorbent 1
′ Also adsorbs not only the combustion gas, but also the moisture generated by thermal decomposition and combustion in the combustion chamber, and part of the air that is the combustion-supporting gas. Therefore, after adsorption by the adsorbent 1 ′, the switching valve 15 is turned on. By operating again, pyrolysis, a purge gas (nitrogen gas) is fed into the combustion chamber, and the purge gas is caused to flow into the primary adsorption pipe to separate the moisture adsorbed by the adsorbent 1'and the air from the adsorbent. Discharge to the outside of the next adsorption tube. by this,
The adsorbent 1'purely adsorbs only the combustion gas.

When the adsorption process for the adsorbent 1'in the primary adsorption tube is completed in this manner, the primary adsorption tube is removed from the primary adsorption unit, and the headspace sampler 3 is turned upside down.
0 into the insertion recess 31, the secondary adsorption pipe 2 wound with the ferromagnetic metal foil 3 is also inserted into the insertion recess 32, and the upper end of the primary adsorption pipe is closed with the lid 36 having the ventilation pipe 37. A lid 45 closes the upper end of the insertion recess 32. And the heater 3 for heating
3, the primary adsorption tube is heated to 280 ° C., the combustion gas adsorbed by the adsorbent 1 ′ in the tube is desorbed from the adsorbent, and the cooler 35 brings the secondary adsorption tube 2 to −100 ° C. It cools, and at the same time, the valve body of the switching valve 50 is set to the first rotation position and the first
The flow channel 41 and the second flow channel 42 are connected to each other, and a purge gas such as high-purity nitrogen gas is supplied into the first adsorption pipe through the ventilation pipe 37,
The combustion gas desorbed from the adsorbent 1'is sent from the lower end into the second adsorption pipe by the purge gas, and is adsorbed by a small amount of the adsorbent 2'in the pipe whose adsorption capacity is enhanced by cooling.
The purge gas is supplied from the upper end of the insertion recess 32 to the communication passage 4
4, then discharged through the third valve passage 53 and the gas discharge passage 39.

When the adsorption by the adsorbent 2'in the secondary adsorption tube is completed, the heater 33 for heating is energized, the cooler 35 is cooled,
The supply of the purge gas from the ventilation pipe 37 is stopped, the valve body 50 ′ of the switching valve is set to the second rotation position, and the high frequency power supply 46 is applied to the high frequency coil 35 for the time controlled by the timer 46. Blow the carrier gas into the passage 38. As a result, the ferromagnetic metal foil 3 wound outside the secondary adsorption tube is instantly (about 0.2 seconds) 235 of the Curie point.
The secondary adsorption tube 2 is heated by heating to ℃ and the adsorbent 2'in the tube is heated.
The combustion gas adsorbed on the exhaust gas is desorbed from the adsorbent, and the carrier gas is supplied from the supply passage 38 to the second valve passage 52 and the communication passage 44.
The combustion gas that has entered the second adsorption pipe from the upper end via the above and is desorbed from the adsorbent 2 ′ is sent to the capillary column 40 of the gas chromatograph via the second flow passage 42 and the third valve passage 53, so that analysis can be performed. it can.

The combustion gas desorbed from the adsorbent 1'of the primary adsorption pipe is moved into the second adsorption pipe from the lower end by moving the valve body 50 'of the switching valve to the first rotation position and adsorbed inside the pipe. Adsorb to agent 2 '. As a result, the combustion gas is concentrated to a higher concentration toward the lower end of the adsorbent in the second adsorption pipe. When the combustion gas adsorbed by the adsorbent 2'of the second adsorption pipe is desorbed and is fed into the capillary column 40 by the carrier gas, the valve body of the switching valve is reversed to the second rotation position, and the carrier gas is discharged to the second position. Since it is supplied from the upper end into the adsorption tube, the recovery efficiency of the combustion gas supplied to the capillary column is high. The thickness of the ferromagnetic metal foil that surrounds the outer periphery of the second adsorption tube is, for example, about 50 μ and has a small heat capacity, so that the cooling is performed immediately after the heating by the high-frequency coil 34 is finished, so that the analysis time is shortened.

FIG. 5 is a gas chromatogram obtained by analyzing the combustion gas component of polystyrene by the method of the present invention, and FIG. 6 is a gas chromatogram obtained by analyzing the combustion gas component of the same polystyrene by the conventional method. . The gas chromatogram obtained by the method of the present invention in FIG. 5 can detect a large number of high-boiling components that are difficult or undetectable by the conventional method, and the analysis accuracy is remarkably improved.

[0017]

According to the method of the present invention, since the pyrolysis process and the combustion process are separated, the gas generation condition becomes constant, and accordingly, the combustion process becomes stable and the data is reproducible. Become. On the other hand, in the conventional example, the thermal decomposition and the combustion process coexisted, and thus the reproducibility was not obtained. In addition, a component having a large molecular weight is adsorbed on the inner surface of a nylon-based laminate bag for collection and cannot be subjected to analysis, and according to the method of the present invention, the sample to be analyzed for combustion is The yield of the target component can be improved by using an adsorbent that can efficiently adsorb and concentrate only the combustion gas and efficiently desorb. Furthermore, because the adsorption process is divided into two stages, 1
Since the required amount of adsorbent can be prepared for the next adsorption, a high concentration effect can be achieved even for extremely low-concentration combustion gas, and as a result, it is possible to use a narrow high-concentration bandwidth on the gas chromatograph, which is the final measurement means. Introduction and separation analysis can be performed, and analysis with much higher sensitivity than before becomes possible. Further, it is possible to remove moisture and combustion-supporting gas contained in the combustion gas, which has hindered the analysis in the past, to enable concentration of the organic gas component, and to introduce this gas into a gas chromatograph for separation analysis.

[Brief description of drawings]

FIG. 1A is a schematic view showing a state in which a primary adsorption tube is attached to a primary adsorption unit to adsorb and concentrate a combustion gas of a sample, and at the same time, an inorganic gas such as water is purged.
(B) is a schematic diagram showing a state in which the secondary adsorption pipe of the headspace sampler is induction-heated, the secondary-adsorbed combustion gas is released, and is introduced into the gas chromatograph via a valve.

FIG. 2 is an enlarged view of FIG.

FIG. 3 is a schematic view showing a state in which a suction tube and a second suction tube are attached to a headspace sampler to perform secondary suction.

FIG. 4 is an enlarged view of FIG.

FIG. 5 is a gas chromatogram of combustion gas obtained by burning styrene obtained by the method of the present invention. Other than styrene, indene, naphthalene, etc. have been detected.

FIG. 6 is a gas chromatogram of the combustion gas obtained by burning the same sample obtained by the conventional method.

[Explanation of symbols]

 1 Primary adsorption tube 1'Adsorbent in primary adsorption tube 2 Secondary adsorption tube 2'Adsorption agent in secondary adsorption tube 3 Ferromagnetic metal foil 4 Glass wool 5 Liquid or solid plastic sample 6 Ferromagnetic metal foil 10 Heat Disassembly / combustion chamber 11 Holding base 12 Ignition device 13 High frequency coil 14 Switching valve 15 Insulation pipe 20 Primary adsorption unit 21 Cooler 30 Headspace sampler 31 Primary adsorption tube insertion recess 32 Secondary adsorption tube insertion recess 33 For heating Heater 34 Cooler 35 High frequency coil 36 Primary adsorption pipe lid 37 Purge gas vent pipe 38 Carrier gas supply flow passage 39 Gas discharge flow passage 40 Capillary column 41 First flow passage 42 Second flow passage 43 Analysis flow passage 44 Communication flow Channel 45 lid for insertion of secondary adsorption tube 46 auxiliary channel 47 high-frequency power source 48 timer 50 switching valve 50 'valve body 51st Benro 52 second Benro 53 third Benro 54 4 Benro

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G01N 30/88 C

Claims (2)

[Claims] 1. A plastic liquid or solid sample is wrapped in a ferromagnetic metal foil for pyrolysis and stored in a combustion chamber, the ferromagnetic metal foil is induction heated to pyrolyze the sample, and then placed in a decomposition combustion chamber. While injecting the combustion-supporting gas, the pyrolysis gas is ignited in the room to generate combustion gas, and the combustion-supporting gas also supplies the combustion gas to the primary adsorption pipe filled with a large amount of adsorbent to adsorb in the pipe. Combustion that is adsorbed by the adsorbent by adsorbing the adsorbent on the agent, and after the adsorption, supplying a purge gas into the primary adsorption tube to discharge the combustion-supporting gas adsorbed by the adsorbent and the moisture generated by the combustion to the outside of the tube. The gas was concentrated, then a small amount of the above-mentioned primary adsorption tube and an adsorbent were filled inside, and a ferromagnetic metal foil was wound on the outside.
A secondary adsorption tube is held in a headspace sampler, the secondary adsorption tube is cooled, and the primary adsorption tube is heated to introduce combustion gas adsorbed by the adsorbent into the secondary adsorption tube. Adsorb to a small amount of adsorbent in the adsorption tube, and after the adsorption, 2
Induction heating of a ferromagnetic metal foil outside the next adsorption tube to volatilize the combustion gas adsorbed by the adsorbent, and the volatile gas is introduced into a gas chromatograph. . 2. A high-frequency coil having a holding base for holding a ferromagnetic metal foil enclosing a plastic liquid or solid sample and an igniter therein, and for inductively heating the ferromagnetic metal foil enclosing the sample. Is wound outside, and with combustion-supporting gas,
The pyrolysis and combustion chambers that are switched to the purge gas and fed into the interior, the primary adsorption pipe that is removably connected to the pyrolysis and combustion chambers, and is filled with a large amount of adsorbent inside. A primary adsorption unit that removably holds and cools the adsorption tube, a secondary adsorption tube filled with a small amount of adsorbent inside and a ferromagnetic metal foil wound on the outside, and the primary adsorption tube is heated. Possibly equipped with a high-frequency coil for holding each of the secondary adsorption tubes in a coolable manner and inductively heating the ferromagnetic metal foil outside the secondary adsorption tubes, and the secondary adsorption tube with the primary adsorption tube and the gas chromatograph. A head space sampler having a switching valve that selectively communicates with a capillary column, and a combustion analysis apparatus for a plastic sample by a gas chromatograph.