US3904368A

US3904368A - Burning and collection apparatus for combustion gases

Info

Publication number: US3904368A
Application number: US338194A
Authority: US
Inventors: Kenichi Takeyama; Takayoshi Morimoto; Fumiya Konishi
Original assignee: Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Holdings Corp
Priority date: 1972-03-07
Filing date: 1973-03-05
Publication date: 1975-09-09
Anticipated expiration: 1992-09-09
Also published as: DE2310811B2; GB1423232A; DE2310811A1; FR2175483A5; AU5301873A; CA977181A; AU463559B2

Abstract

A burning and collection apparatus for combustion gases, comprising a combustion unit having a combustion chamber in which a sample material is to be burned and an electric heating furnace, a gas supply unit for introducing air or gas at an optionally adjusted predetermined rate, a piston-cylinder type gas collection unit for collecting the combustion gases generated in said combustion chamber, and a driving unit for operating said piston at an optionally adjusted predetermined speed, whereby a sample material such as plastics can be burned under an optional temperature and an optional supply rate of air, and the resulting combustion gases can be collected without substantially diluting them and hence the composition of the combustion gases can be analyzed with high accuracy.

Description

United States Patent [191 Takeyama et a1.

[ 51 Sept. 9, 1975 BURNING AND COLLECTION APPARATUS FOR COMBUSTION GASES [73] Assignee: Matsushita Electric Industrial Co.,

Ltd., Kadoma, Japan [22] Filed: Mar. 5, 1973 [21] Appl. No.: 338,194

3,529,937 9/1970 Ihara ct al 23/253 PC 3,542,121 11/1970 Koartinen 23/253 PC UX 3,811,839 5/1974 DiPietro et al. 23/253 PC Primary Examiner.loseph Scovronek Attorney, Agent, or Firm-Stevens, Davis, Miller & Mosher [5 7] ABSTRACT A burning and collection apparatus for combustion gases, comprising a combustion unit having a combustion chamber in which a sample material is to be burned and an electric heating furnace, a gas supply unit for introducing air or gas at an optionally adjusted predetermined rate, a piston-cylinder type gas collection unit for collecting the combustion gases generated in said combustion chamber, and a driving unit for operating said piston at an optionally adjusted predetermined speed, whereby a sample material such as plastics can be burned under an optional temperature and an optional supply rate of air, and the resulting combustion gases can be collected without substantially diluting them and hence the composition of the combustion gases can be analyzed with high accuracy.

4 Claims, 4 Drawing Figures BURNING AND COLLECTION APPARATUS FOR COMBUSTION GASES This invention relates to a burning and collection apparatus for combustion gases, which is used in analyzing the composition of the combustion gases generating upon burning a sample material such as plastics, by burning the sample material and collecting the combustion gases.

In recent years, building fire in which many human lives are lost is one of the social problems. It is said that such casualty is caused by, among others, the toxic gases generating by the combustion of plastic materials, such as carbon monoxide, hydrogen cyanide, hydrogen chloride, phosgene, carbonyl sulfide, etc. It is, therefore, desired to selectively use plastic materials for particular applications while taking into account the composition of the combustion gases which each plastic material will generate at the time of fire. The combustion gases generated when a material is burned contain gases which are generated by the burning of the material with flames and gases which are generated by the thermal decomposition of the material without accompanying flames. Thus, it is necessary, in determining the composition of the combustion gases generating from a plastic material at the time of fire, to determine the compositions of both types of gases, Many reports huVC been made concerning the composition of the gases which are generated when plastic materials are subjected to thermal cracking in an inert gas atmosphere or under reduced pressure, but few reports have been made concerning the composition of the gases which are generated when plastic materials are burned or subjected to chemical change accompanying light and heat.

Conventional burning and collection apparatus used for the composition analysis of combustion gases are classified broadly into the following types:

I. A type in which a sample material is burned in the atmosphere and the resulting combustion gases are collected in a large container disposed above the sample material by taking advantage of the ascending and dissipation of the combustion gases.

I]. A type in which a sample material is heated by an electric heater in a flask having air or an inert gas such as nitrogen gas sealed therein, and the resulting gases are collected in the flask and a balloon connected to said flask for relieving the pressure building up in said flask.

III. A type in which a sample material placed in a magnetic boat with an iron piece attached thereto is inserted in a combustion tube, located at a heating por tion in said combustion tube by shifting said magnetic boat externally by means of a magnet and burned at said heating portion in air or an inert gas, such as nitrogen gas, introduced into said combustion tube at a pre' determined rate, and the resulting combustion gases are collected in a flask which has previously been reduced in pressure.

However, the apparatus of the type I has had the disadvantages that the composition analysis cannot be achieved with high accuracy since the combustion gases are diluted with a large quantity of air, and that the combustion is possible only in air and the atmospheric gas cannot be changed optionally. The apparatus of the type II has suffered the disadvantage that when the material is burned in the flask in which is sealed air, the oxygen concentration in the flask decreases as the burning proceeds and pressure is built up in said flask by generated gases though the balloon is inflated, so that it is impossible to burn the material under the same conditions from the start to end of the burning. The apparatus of the type III has had the disadvantages that the regulation of the supply rate of air or inert gas relative to the decreasing pressure in the flask is difficult and hence the combustion conditions can hardly be maintained constant, namely if the supply rate of air or inert gas is too high, combustion under pressurized state will result while conversely, if the supply rate is too low, combustion under reduced pressure state will result, and that, therefore, the combustion conditions vary between the start and end of combustion though not to such a large degree as in the apparatus of the type II.

An object of the present invention is to provide a burning and collection apparatus for combustion gases in which a sample material can be burned under the same conditions from the start to end of the combustion and the resulting combustion gases can be collected without substantially diluting them.

Another object of the invention is to provide a burning and collection apparatus for combustion gases, in which the temperature of a combustion chamber and the supply rate of air or inert gas to said combustion chamber can optionally be adjusted, and various combustion conditions can be reproduced.

Still another object of the invention is to provide a burning and collection apparatus for combustion gases, in which, in the event when the combustion gases generated are soluble in water, the combustion gases can be collected substantially entirely in the gaseous state without dissolving them in water, such as moisture.

A further object of the invention is to provide a burning and collection apparatus for combustion gases, in which an air having an oxygen concentration different from the atmospheric air, or an inert gas, such as nitrogen gas, is used in lieu of the atmospheric air, whereby combustion gases in different atmospheres can be collected.

Namely, the burning and collection apparatus according to the invention is characterized in that it comprises a combustion unit consisting of a combustion chamber in which a sample material is to be placed and a heating furnace for heating said combustion chamber, a gas supply unit for introducing a predetermined rate of air or other gas into said combustion chamber, and a piston-cylinder type gas collection unit for sucking the combustion gases generated in said combustion chamber.

The combustion chamber is made preferably of materials which do not react with combustion gases and highly resistive to heat, e.g. quartz. The heating furnace may be of electric heater type or gas burning type, but the electric heater type is preferred in view of stability and ease in adjustment of the heating temperature, and sanitation. As the gas supply unit, an air pump of the like is used when air in the atmosphere is to be supplied, or means for mixing nitrogen or oxygen gas in air is used when an air of oxygen concentration different from that of the atmospheric air is to be used, or a bomb containing an inert gas, such as nitrogen gas, is used when such inert gas is to be used. However, the atmospheric air is generally used in the operation of the subject apparatus and, therefore, the apparatus will be described hereunder as comprising an air supply unit.

The air supply unit is preferably of a type by which the supply rate of air per unit time can optionally be adjusted and which is capable of supplying air at a stable rate. Such type of air supply unit includes an air pump. a blower and a bomb. Further, when the atmospheric air is to be supplied, it is desirable to provide dehumidization means in the air supply line on the downstream side of the combustion chamber so that water-soluble gases in the combustion gases resulting from combustion may not dissolve in water contained in air. The piston-cylinder type gas collection unit may be of a type in which a piston is moved or a cylinder is moved with the piston fixed, for sucking the combustion gases generated in the combustion chamber. The piston or cylinder may be operated either manually of by an operating device. It is essential, however, that the quantity of air supplied per unit time by the air supply unit and the quantity of gases sucked per unit time by the gas collection unit be substantially equal so as not to create a pressurized condition or reduced pressure condition in the combustion chamber, or to maintain said combustion chamber at normal pressure condition. To this end, an Operating device, such as a motor, is generally used to operate the piston or cylinder at a constant speed. The piston or cylinder operating device, similar to the air supply unit, is preferably of a type by which the suction rate of gas can optionally be adjusted. However, even with such operating device, it is extremely difficult to make exactly equal the supply rate of air and suction rate of gas. Therefore, the dimensions of the piston and cylinder are selected preferably so as to provide therebetween sealing effect to such a degree that, when a pressure differential has occurred between the interior and exterior of the cylinder upon displacement of either the piston or cylinder relative to each other, air may move into the cylinder to eliminate the pressure differential, whereas when a pressure differential has not occurred, the movement of air may be blocked, and thereby to maintain the suction rate of gas slightly larger than the supply rate of air. If the suction rate of gas is simply made slightly larger than the supply rate of air, a reduced pressure condition will appear in the combustion chamber. However, by selecting the dimensions of the piston and cylinder as described above, a slight amount of air flows into the cylinder as the internal pressure of the cylinder tends to decrease below the atmospheric pressure at the time of suction operation, whereby the development of sub-atmospheric pressure in the cylinder and combustion chamber can be prevented and substantial dilution of the collected gases can be avoided, and further the adjustment of the operating speed of the operating device can be facilitated. The inner walls of the cylinder and piston which are contacted by the combustion gases should be coated with materials little reactive with the gases, e.g. fluorine-containing resin and polyethylene, or the cylinder and piston should be made of such materials, so that said inner Walls may not be attacked by the combustion gases. Water-soluble combustion gases may be generated occasionally depending upon the type of sample material burned. If the aqueous vapour generated in the combustion chamber on such occasion are collected in the cylinder along with other combustion gases, the water-soluble gases will be dissolved in the water formed in the cylinder upon cooling of the aqueous vapour. Thus, the gases insoluble in water will be collected in the gaseous state and the gases soluble in water in the form of solutions in water, so that the subsequent analysis of gas composition cannot be completed at once. It is, therefore, recommended to provide between the combustion chamber and gas collection unit cooling means for cooling the gases to be collected and liquefying the aqueous vapour entrained therein, and thereby to remove the water from the gases so as not to be collected in the gas collection unit. As the cooling means, a conduit connecting the combustion chamber with the cylinder may be elongated so that the aqueous vapour may be cooled and condensed by the external air during passage in said elongate eonduit. It is possible to contact cold water with the outer surface of the conduit to forcibly cool and condense the aqueous vapour. Further, it is advantageous, for enhancing the accuracy of analysis, to provide filter means in the conduit between the combustion chamber and cylinder to remove smoke and soot from the combustion gases before they are collected in the cylinder.

FIG. I is a diagram showing the layout of an embodiment of the burning and collection apparatus for combustion gases, according to the invention;

FIG. 2 is a sectional view of the combustion unit of the apparatus, showing the arrangement to measure the temperature of said combustion chamber;

FIG. 3 is a sectional view of the piston-cylinder type gas collection unit; and

FIG. 4 is an end view of the gas collection unit.

Now, an embodiment of the present invention will be described with reference to the drawings.

In the drawings, reference numeral 1 designates a combustion unit in which sample materials such as plastics are to be burned. The combustion unit 1 includes a quartz cylindrical combustion chamber 2 and a heating furnace 3 surrounding said combustion chamber '2 externally. The combustion chamber 2 has an inner diameter of 46 mm and a height of 220 mm, and is provided at its bottom with a gas inlet port 4 extending outwardly through the heating furnace 3 and at its top with a gas outlet port 5 and a sample supply port 7 which is opened and closed by a cap 6. Quartz beads 8 are filled in the combustion chamber 2 up to a level 75 mm from the bottom of said chamber. The heating furnace 3 has an inner diameter of 60 mm and a height of 200 mm, and is provided with an electric heater therein. Namely, the heating furnace 3 is of so-called electric heating type. Reference numeral 9 designates an air supply unit for supplying air to the inlet port 4 of the combustion chamber 2. This air supply unit 9 consists of an air pump of a type in which the supply rate of air per unit time is adjustable, and is connected to the inlet port 4 by a gas supply passage 10. Reference numeral 11 designates a dehumidization unit provided in the gas supply passage 10 and consists of a tank 12 with desiceants such as silica gel 13 disposed therein. A section of the gas supply passage 10 leading from the air pump 9 is opened in the bed of silica gel 13 and another section of said gas supply passage 10 leading to the combustion chamber 2 is extended from the top of the tank 12 spaced above the bed of silica gel 13. In the gas supply passage 10 on the downstream side of the dehumidization unit 11 is provided a flow meter 14 which indicates the quantity of air supplied to the combustion chamber 2 in a unit time. Reference numeral 15 designates a piston-cylinder type gas collection unit for collecting the combustion gases generating in the combustion chamber 2. This gas collection unit consists of a cylindrical cylinder 17 communieating with the gas outlet port 5 of the combustion chamber 2 through a gas exhaust passage 16, and a piston 18 disposed in said cylinder 17 for sliding movement therein. The cylinder 17 has a cross-sectional area of 177 cm' and an internal volume of 4 l, and is made of stainless steel. The inner wall of the cylinder 17 is lined with a coating film 19 of a material little reactive with the combustion gases collected, e.g. poly tetrafluoroethylene or polyethylene. The piston 18 is provided with a rope-shaped seal ring 20 which is made of a tetrafluoroethylene having a Shore hardness of 50-65 and mounted on the outer peripheral surface thereof in light contact with the inner surface of the cylinder 17. The seal ring 20 provides a sealing effect between the piston 18 and the cylinder 17 to such a degree that, when a pressure differential has occurred between the interior and exterior of the cylinder 17 upon displacement of the piston 18 relative to said cylinder, air is permitted to flow into the cylinder through between the seal ring 20 and the inner wall of the cylinder 17 to eliminate said pressure differential, but when the piston 18 is held stationary, air flow between the interior and exterior of the cylinder 17 is blocked. The inner wall of the piston 18 which will be contacted by the combustion gases collected in the cylinder 17 is coated with a coating film 19' of the same material as the coating film 19. The gas exhaust passage 16 is formed of a polytetrafluoroethylene tube having an inner diameter of 8 mm and a length of 1.5 In, said tube consisting of a plurality of sections detachably coupled together by means of couplings 21. In the gas exhaust passage 16 is provided filter means 22 which consists of a cylindrical casing communicating with said gas exhaust passage 16 and packed with glass wool 23. A driving device 24 is provided to cause displacement of the'piston 18 within the cylinder 17, which comprises a motor 25, a stepless speed change gear 26 connected with said motor 25 and a guide structure 28 interconnecting said stepless speed change gear 26 and a piston rod 27 of the piston 18. The guide structure 28 is composed of opposed fixed

support plates

30, 31, an externally threaded rod 29 connected with the stepless speed change gear 26 and rotatably supported by said

support plates

30, 31, a guide rod 32 extending across said

support plates

30, 31 with the opposite ends secured thereto respectively, and a movable plate 33 slidably mounted on said guide rod 32 at one end with said threaded rod 29 threadably extending therethrough and having the piston rod 27 connected to the other end thereof.

The burning and collection apparatus for combustion gases, of the construction described above is operated in the following sequence: Namely, the combustion.

chamber 2 is heated by the electric type heating furnace 3 at first and then the air pump 9 is set in motion to feed air into the combustion chamber 2, after open ing the sample material supply port 7 of said combustion chamber. The air supplied from the air pump 2 is dehumidized during passage through the dehumidization unit 11 by the silica gel 13 disposed in said dehumidization unit. The dry air leaving the dehumidization unit 11 after passage through the silica gel 13 passes in the flow meter 14 and enters the combustion chamber 2 from the gas supply port 4. The flow rate of air from the air pump 9 is regulated to a desired value, e.g. lOO l/hr. on the flow meter 14. The air entering the combustion chamber 2 is heated therein and discharged to the outside from the sample material supply port 7. The temperature of the combustion chamber 2 or, more specifically, the temperatures of the surface of the quartz beads 8 and the inner wall of the combustion chamber 2 which are heated most, are measured by means of a thermocouple 34 inserted into the combus tion chamber 2 from the sample material supply port 7, to adjust the temperature of said combustion chamber 2 to a desired value, e.g. 700C., by controlling the current being supplied to the electric heating furnace 3. The stepless speed change gear 26 is previously adjusted such that the quantity of gases sucked in a unit time will be slightly larger than the quantity of air supplied in a unit time by the air pump 9, and then the motor 25 is set in motion to operate the piston 18 for suction stroke. In this case, the externally threaded rod 29 rotates and the moving plate 33 in threadable engagement with said rod 29 displaces towards the motor 25 along the rod 29 and the guide rod 28, whereby the piston 18 is pulled for suction stroke. Simultaneously with starting the suction stroke, a predetermined weight of a sample material is placed in the combustion chamber 2 from the sample material supply port 7 and then said supply port 7 is closed by the cap 6. The sample material placed in the combustion chamber 2 burns therein generating a variety of combustion gases. The combustion gases in most cases contain aqueous vapour. The combustion gases thus generated ascend in the combustion chamber 2 and are collected in the cylinder 17 through the gas exhaust passage 16. The aqueous vapour entrained in the combustion gases is cooled and condensed while the combustion gases are passing in the gas exhaust passage 16 which is considerably long, and the resulting water attaches to the inner wall of the exhaust passage 16 and to the glass wool in the filter means 22, in the form of water droplets. The smoke and soot resulting from the combustion are removed from the combustion gases by the filter means 22 during passage of the combustion gases in said filter means, and little of them reach the cylinder 17. A subatmospheric pressure condition tends to occur in the cylinder 17 and combustion chamber 2 in the suction stroke of the piston 18 since the suction rate of gases into the gas collection unit is slightly larger than the supply rate of air from the air pump 9. In practice, however, such condition does not occur and the cylinder 17 and combustion chamber 2 are maintained at substantially normal pressure, because the external air flows into the cylinder 17 through between the seal ring 20 mounted on the piston 18 and the inner wall of the cylinder 17. Therefore, in'no case will the rate of air supplied into the combustion chamber 2 vary due to the pressure reduction otherwise occurring in said combustion chamber, and hence the combustion conditions can be maintained constant. The combustion gases are collected in the cylinder 17 at high concentrations in a short period of time, e.g. l 2 minutes, after the piston 18 has ceased its movement without substantially being allowed to leak to the outside, though they are diluted slightly with air. Thus, the combustion gases generating in the combustion chamber 2 are introduced entirely into the cylinder 17. In this case, the distance of displacement of the piston 18 for suction is measured to know the total volume of the gases collected. In the experiment conducted by the present inventors, however, the piston was pulled over a constant distance so that the total volume of the gases collected might be constant. It was confirmed that the combustion gases remaining in the combustion chamber 2 could be collected entirely in the cylinder 17, by pulling the piston 18 further over 5 cm continuously after the completion of combustion of the sample material. Immediately after the combustion gases have been collected in the cylinder 17 in the manner described, the piston rod 27 is removed from the moving plate 33, the section of the gas exhaust passage 16 leading to the cylinder 17 is disconnected from the remaining section at the coupling 21, a cylindrical gas cell for infrared absorption spectrum, having an internal volume of 250 cc, a light path length of cm and a reduced pressure below 0.5 torr is connected to the disconnected end of said section of the gas exhaust passage 16, and the combustion gases in the cylinder 17 are forced into said gas cell with pressure by pushing the piston 18 by hand. In the experiment, the pressure of the combustiongases was returned to the atmospheric pressure just before the measurement. It was also confirmed that the combustion gases collected in the cylinder 17 are dissipated sufficiently within said cylinder even right after the collec tion and segregation of gases is not seen anywhere in the cylinder.

In order to evaluate the accuracy of the subject apparatus in its combustion gas generation and collection operation, 0.1 g of nylon 66 was burned six times each under such combustion conditions that the combustion temperature was 700C, and the supply rate of air was 100 l/hr, and the quantitative analysis of the components of the combustion gases in each run was conducted by the infrared absorption spectrum method, with the results shown in the table provided below:

In the above table numerical values are expressed in ml/g, Y represents the mean value and C.V.(7() represents the standard deviation percentage.

It was found that the quantities of the components other than ammonia can be determined with the standard deviation within 10%, as shown in the above table. The accuracy in determination of ammonia is poor probably because ammonia is generated in a small quantity in case of nylon 66 and also because the quantity of ammonia generated is influenced even by a slight change in the combustion conditions. The accuracy in determination of acetylene was also somewhat poor because the quantity of acetylene formed is varied by a slight change in combustion conditions, particularly in the supply rate of air. It was confirmed that the quantitative analysis of other plastics can be achieved with the same accuracy as in the case of nylon 66. Since the accuracies depicted above include the error inherent to the determination by the infrared absorption spectrum, it is assumed that the actual accuracies is the formation and collection of combustion gases by the subject apparatus would be better than those shown in the table provided above.

The present inventors conducted another experiment to determine the proportion in which a water-soluble gas is collected in the cylinder 17 in the gaseous state when such water-soluble gas is generated in the combustion chamber 2. In the experiment, 0.1 g of polyethylene which generates a large quantity of water when burned was placed in the combustion chamber 2 and burned therein under the same conditions under which it is normally burned, i.e. at a temperature of 700C. and with air supplied at the rate of 100 I/hr. In collecting the resulting combustion gases in the cylinder 17, the aqueous vapour present therein was removed therefrom by condensing it in the gas exhaust passage 16. Concurrently with the completion of combustion, 6.06 cc of ammonia gas was introduced into the combustion chamber from the supply port 4 along with 100 l/hr or air. The ammonia gas was collected in the cylinder 17 through the gas exhaust passage 16. The quantity of ammonia gas collected in the cylinder 17 was of that introduced from the supply port 4. Thus, it will be understood that only 10% of the ammonia gas had been dissolved in water before the ammonia gas reached the cylinder 17. It is generally known that plastics or other materials which will generate water-soluble gases when burned, produce less amounts of water than the aforesaid polyethylene and that plastics generate all of the water-soluble gases which are to be generated therefrom, in the initial stage of combustion in which the quantity of water produced is relatively small. In view of the above, it is assumed that the proportion of the water-soluble gas actually collected in the cylinder 17 would be more than The present invention has been described herein in terms of an embodiment in which the atmospheric air is introduced into the combustion chamber. It should be understood, however, that according to the invention combustion under a variety of conditions can be reproduced in the apparatus by introducing into the combustion chamber airs having oxygen concentrations different from that in the atmospheric air, and other oxygen-containing gases. It should also be understood that gases resulting from thermal decomposition can be formed and collected in the apparatus by introducing inert gases, such as nitrogen gas, in lieu of air.

As may be understood from the foregoing description, the apparatus of the invention is advantageous in that the supply rate of air or other gas introduced into the combustion chamber and the flow rate of the gases generated in said combustion chamber and being led to the gas collection unit can be balanced and in that the conditions under which the combustion or thermal decomposition is carried out can be maintained unchanged from the start to end of the combustion or thermal decomposition, without allowing superor subatmospheric pressure to develop in the combustion chamber. The apparatus is also advantageous in that the gases generated in the combustion chamber can be collected in the gas collection unit without substantially diluting them, and hence the analysis of gas composition can be achieved with high accuracy.

It should also be noted that according to the invention the temperature of the combustion chamber and the supply rate of air to said combustion chamber can optionally be adjusted and a variety of combustion conditions can be reproduced. The mode of combustion of an inflammable material in the actual fire varies largely depending upon the state of fire. For instance, inflammable materials decompose at relatively low temperatures in the initial stage of combustion, generating gases which constitute smokes. By using the apparatus of the invention, the gas generating states under various conditions can be known by changing the temperature of the combustion chamber. In the case of fire in buildings, air is short in most cases, whereas in the case of fire of wooden houses air is supplied sufficiently in most cases. With the apparatus of the invention, the combustion under various conditions can be reproduced by changing the supply rate of air to the combustion chamber in the light of the foregoing facts.

It is an additional advantage of the invention that, since the gas exhaust passage is provided between the combustion chamber and cylinder, which has a cooling effect sufficient to condense aqueous vapour and by which water is prevented from being collected in the cylinder, water-soluble gases can be collected in said cylinder substantially entirely in the gaseous state even if such gases are generated in the combustion chamber, and therefore, the quantitative analysis of the watersoluble gases can be achieved simply by the same method as that for the quantitative analysis of other combustion gases or thermal decomposition gases.

It should also be noted that in the apparatus of the in- .vention the generation and collection of combustion gases and thermal decomposition gases in a variety of atmospheres are possible by supplying into the combustion chamber airs having oxygen concentrations different from that in the atmospheric air or inert gases such as nitrogen gas, besides the atmospheric air.

What is claimed is:

1. A burning and collection apparatus for combustion gases, comprising combustion means having a combustion chamber for placing sample material therein and an electric heating furnace capable of adjustably heating said combustion chamber, gas supply means for supplying air or other gas into the combustion chamber at an adjustable rate, piston-cylinder type gas collection means having a cylinder communicating with the combustion chamber by a gas exhaust passage having a cooling effect sufficient to condense aqueous vapor and a piston disposed slidably in said cylinder, the gas being collected in a collection chamber defined by said piston and the interior of said cylinder, driving means for creating relative movement between the piston and cylinder at an adjustable predetermined speed and in a direction causing suction of the combustion gases into the collection chamber so that said suction is at a rate corresponding to the supply rate of air or other gas into the combustion chamber, the dimensions of said cylinder and piston being such that sealing is created between said cylinder and piston wherein gas is allowed to flow into said collection chamber between said cylinder and said piston to eliminate the pressure differential between the interior and exterior of said cylinder caused by the sucking of said combustion gases by said piston, and when combustion gases are not being sucked, gas flow between said piston and said cylinder is prevented.

2. A burning and collection apparatus for combustion gases, comprising combustion means having a combustion chamber for burning a sample material received therein and a heating furnace for adjustably heating the sample material in said combustion chamber, gas supply means for leading to an inlet of said combustion chamber air or other gas at a predetermined and adjustable rate, dehumidizing means for removing moisture from the combustion gases exciting through an outlet of said combustion chamber by cooling said combustion gases and thus condensing an aqueous vapor contained therein, a cylinder for receiving the combustion gases from said dehumidizing means and a piston slidably fitted in said cylinder, said piston and said cylinder defining a collection chamber, driving means for displacing said piston at a predetermined and adjustable rate in a direction to cause suction of the combustion gases into said collection chamber, said piston being provided on its outer periphery with seal ring means which is in light contact with the inner surface of said cylinder, so that gas is allowed to flow past said ring into said collection chamber when a pressure differential is created across said ring due to the suction in said collection chamber caused by the displacement of said piston and flow of gas past said ring is prevented when said piston is stationary.

3. The apparatus of claim 2 wherein said cylinder is open to the atmosphere at one end, and said piston forms a single collection chamber with the inside and the other end of said cylinder for collecting said combustion gases by suction at a rate equal to the supply rate of air or other gas into said combustion chamber, said sealing ring allowing flow of gas into said collection chamber from the atmosphere when displacement of said piston causes suction in said collection chamber and preventing flow communication of gases between the atmosphere and the collection chamber between said cylinder walls and said piston when said piston is stationary.

4. A method of producing and collecting combustion gases comprising:

heating sample material in a combustion chamber;

supplying air or other gas at a predetermined and adjustable rate into said combustion chamber to burn the sample;

removing moisture from the combustion gases produced in said combustion chamber which gases have exited through an outlet of said combustion chamber; and

collecting said dehumidified combustion gases at substantially constant pressure and at a rate corresponding to the rate of supply of air or other gas into the combustion chamber, said collection taking place in a collection chamber defined by a movable piston and a cylinder having a seal between said piston and cylinder for maintaining substantially constant pressure in said collection chamber by allowing gases at atmospheric pressure to enter said collection chamber when suction is created therein by movement of said piston and preventing flow of gas past said seal when said piston is stationary.

Claims

1. A BURNING AND COLLECTION APPARTUS FOR COMBUSTION GASES, COMPRISING COMBUSTION MEANS HAVING A COMBUSTION CHAMBER FOR PLACING SAMPLE MATERIAL THEREIN AND AN ELECTRIC HEATING FURNACE CAPABLE OF ADJUSTABLY HEATING SAID COMBUSTION CHAMBER, GAS SUPPLY MEANS FOR SUPPLYING AIR OR OTHER GAS INTO THE COMBUSTION CHAMBER AT AN ADJUSTABLE RATE, PISTON-CYLINDER TYPE GAS COLLECTION MEANS HAVING A CYCLINDER COMMUNICATING WITH THE COMBUSTION CHAMBER BY A GAS EXHAUST PASSING HAVING A COOLING EFFECT SUFFICIENT TO CONDENSE AQUEOUS VAPOR AND A PISTION DISPOSED SLIDABLY IN SAID CYLINDER, THE GAS BEING COLLECTED IN A COLLECTION CHAMBER DEFINED BY SAID PISTON AND THE INTERIOR OF SAID CYLINDER, DRIVING MEANS FOR CREATING RELATIVE MOVEMENT BETWEEN THE PISTON AND CYLINDER AT AN ADJUSTALE PREDETERMINED SPEED AND IN A DIRECTION CAUSING SUCTION OF THE COMBUSTION GASES NTO THE COLLECTION CHAMBER SO THAT SAID SUCTON IS AT A RATE CORRESPONDING TO THE SUPPLY RATE OF AIR OR OTHER GAS INTO THE COMBUSTION CHAMBER THE DIMENSIONS OF SAID CYLINDER AND PISTON BEING SUCH THAT SEALING IS CREATED BETWEEN SAID CYLINDER AN PISTON WHEREIN GAS IS ALLOWED TO FLOW INTO SAID COLLECTION CHAMBER BETWEEN SAID CYLINDER AND SAID PISTON TO ELIMINATE THE PRESSURE DIFFERENTIAL BETWEEN THE INTERIOR AND EXTERIOR OF SAID CYCLINDER CAUSED BY THE SU KING OF SAID COMBUSTION GASES BY SAID PISTON, AND WHEN COMBUSTION GASES ARE NOT BEING SUCKED, GAS FLOW BETWEEN SAID PISTON AND SAID CYLINDER IS PREVENTED.

4. A method of producing and collecting combustion gases comprising: heating sample material in a combustion chamber; supplying air or other gas at a predetermined and adjustable rate into said combustion chamber to burn the sample; removing moisture from the combustion gases produced in said combustion chamber which gases have exited through an outlet of said combustion chamber; and collecting said dehumidified combustion gases at substantially constant pressure and at a rate corresponding to the rate of supply of air or other gas into the combustion chamber, said collection taking place in a collection chamber defined by a movable piston and a cylinder having a seal between said piston and cylinder for maintaining substantially constant pressure in said collection chamber by allowing gases at atmospheric pressure to enter said collection chamber when suction is created therein by movement of said piston and preventing flow Of gas past said seal when said piston is stationary.