RU134650U1 - COMPLEX FOR RESEARCH OF PROCESSES OF THERMAL DECOMPOSITION OF NON-METAL MATERIAL - Google Patents

Abstract

1. A complex for studying the processes of thermal decomposition of non-metallic material, comprising a furnace for decomposing a sample of material with a temperature unit for monitoring and programmable task of changing the temperature inside the furnace, a sampler for collecting gaseous decomposition products and units of apparatus for controlling gas flows and analysis of decomposition products, characterized in that it additionally contains a thermal analyzer and a condensate decomposition products capture unit installed between the furnace and the sampler lump for collecting gaseous decomposition products, while the condensed decomposition products collection unit consists of sequentially installed separators for collecting high-temperature and low-temperature condensed fractions with the possibility of controlling the thermostat temperature of the separators, and at least two sensors are installed inside the furnace for measuring temperature inside and outside the sample sample or on its surface. 2. The complex according to claim 1, characterized in that for determining the specific thermal effect of thermal decomposition, it additionally contains a calorimeter. The complex according to claim 1, characterized in that it is equipped with a sensor for monitoring pressure inside the furnace and the working chamber. The complex according to claim 1, characterized in that it is equipped with means for regulating the atmosphere inside the furnace and the working chamber.

Description

The utility model relates to test equipment. In particular, it is intended for studying thermal decomposition processes occurring at elevated (from room temperature to 1000 ° C) temperatures by measuring the composition and quantity of thermal decomposition products. By non-metallic material in this utility model is meant polymer or composite (polymer-based) materials. The utility model can also be used to assess the degree of fire safety of products from non-metallic structural and heat-insulating materials used in everyday life, industry and construction, and to establish standards for their use (operation).

Currently, in many industries, as well as in everyday life, products from a variety of non-metallic materials are widely used. In modern construction, these materials are very widely used as thermal insulation, finishing materials and coatings. In emergency conditions (in case of fire), they can undergo heating up to a temperature of 800 ° С and higher, as a result of which gases are released into the environment - products of thermal decomposition of these materials. These gaseous products, primarily hydrogen, methane, ethane, ethylene and many other organic compounds, as well as carbon and nitrogen oxides, are toxic and explosive. The death of people during fires (according to the Ministry of Emergencies, in Russia the annual losses are ~ 13 thousand (!) People) is due, for the most part, to the poisoning by gaseous products of thermal decomposition and burning of materials.

Thus, the study of these processes is of great importance in assessing the degree of safety of products from non-metallic materials, polymers and polymer composites.

In order to conduct computational and experimental assessments of the behavior of structures containing non-metallic, polymer and composite materials, as well as to develop standards that ensure fire safety when using these materials in industry and in everyday life, it is necessary to study how these materials will behave at high temperatures. It is important to note that in order to develop and test theoretical and theoretical models describing the behavior of large samples of polymer materials, it is necessary to measure the temperature distribution in the sample volume under conditions of thermal decomposition.

Currently available standard research thermoanalytical complexes of various foreign companies, such as SETARAM, Mettler Toledo, Perkin Elmer and others, designed to study the processes occurring when heating samples of materials, can provide valuable information about the temperature at which intensive thermal decomposition (thermal decomposition) begins, about composition and mass of gases released, gas evolution rates depending on temperature (http://www.setaram.com, e-mail: sales@setaram.com; http://www.mtrus.com/ta, e-mail: inforus @ mt.com).

At the same time, the aforementioned thermoanalytical complexes have a significant drawback: they cannot be used to answer many questions that arise, first of all, due to the small mass of the samples under study (usually less than 1 g) and, accordingly, their size too small . This results in the impossibility of obtaining the temperature distribution corresponding to a sufficiently large sample on the above equipment, and this is necessary when modeling processes that are closer to reality. In addition, with this equipment it is not possible to achieve the required pressure values or the composition of the gas phase in the heating chamber with the sample, and to measure the pressure in the chamber during heating. The combination of these factors leads to the fact that the data obtained on a commercially available equipment are quite different from those that we would have in conditions closer to real, and therefore the information received is incomplete.

Closest to the claimed complex for studying the process of thermal decomposition of non-metallic materials is a gas analytical complex based on a quadrupole mass spectrometer and pyrolytic prefixes AGKSh-01 manufactured by SHIBBOLET (Ryazan, pr-zd Yablochkova, 5, building 19, http: / /www.shibbolet.ru).

The furnace in the form of a pyrolytic prefix for sample decomposition is equipped with temperature control units inside the furnace, carrier gas flows (2 channels), a gas distribution and regulation (metering) valve in a quadrupole mass spectrometer. The temperature range of the heating furnace is 20-1000 ° C. The complex contains a module for the preparation and inlet of gas samples with an autonomous vacuum system based on a turbomolecular pump, with a thermostat, with the task and control of temperature and pressure in the inlet volumes and regulation (dosing) of the gas sample flow into the mass spectrometer.

The AGKSh-01 complex is intended only for gas-analytical measurements, and there are no possibilities for conducting thermogravimetric and differential thermal analysis in it. It allows you to work with samples larger than in standard thermoanalytic equipment (with a volume of about 100 cm ³ ), however, the system does not provide for measuring the temperature distribution in the sample volume, which is extremely necessary for the calculation and experimental estimates of the behavior of structures containing large-sized samples non-metallic material. In addition, the condensed phase of thermal decomposition products is excluded from the analysis in the well-known gas analysis complex AGKS-01, which significantly limits the possibilities of analysis and reduces its accuracy. In addition, the condensed phase can contaminate the measuring sensors of the system, which also affects the accuracy of the analysis results.

The objective of this utility model is to expand the functionality of existing equipment and increase the accuracy of analysis results.

When using the claimed utility model, the following technical result is achieved:

- conduct on a CETARAM thermal analyzer and a DSK-500 calorimeter, which are part of the inventive complex, a thermal analysis of samples of the studied materials with a volume of up to 1 cm ³ to determine specific heat, rate of thermal decomposition, gas evolution, and characteristic temperature ranges of physicochemical transformations;

- conduct experiments on large-scale samples (up to 4000 cm ³ ), which is unattainable on standard equipment;

- programmable heating to a temperature of 1000 ° C of a reactor previously pumped out or filled with gas of a given initial composition at a pressure of up to 3 atm, and containing a large sample of the material while maintaining the tightness of this vessel and gas pipelines;

- to conduct repeated sampling of gas samples from the working chamber (reactor) during heating and to analyze these samples;

- to divide into fractions by boiling point the condensed thermal decomposition products of polymer materials and to carry out their further research, while condensed thermal decomposition products do not get into the measuring elements of gas analyzers, which eliminates their pollution;

- measure the pressure and temperature of the gas in the reactor with the sample;

- carry out temperature measurements on the surface and inside the sample in order to test calculation methods and simulate thermal processes in large samples;

- to extract a sample of the test material at any time to determine its mass, density, heat capacity, thermal conductivity, mechanical properties.

To solve this problem and achieve a technical result, a complex for studying the processes of thermal decomposition of non-metallic material, containing a furnace for decomposing a sample of material with a temperature unit for monitoring and programmable task of changing the temperature inside the furnace, a sampler for collecting gaseous decomposition products and units of equipment for gas flow control and analysis decomposition products, according to this utility model, the complex additionally contains a thermal analyzer and a capture unit anija condensed decomposition products, mounted between the furnace and the sampler for collecting gaseous decomposition products. The condensed decomposition products recovery unit consists of sequentially installed separators for collecting high-temperature and low-temperature condensed fractions, with the possibility of controlling the temperature of the thermostats of the separators. At least two sensors are installed inside the furnace for measuring temperature inside the sample and outside the sample or on its surface. To determine the specific thermal effect of thermal decomposition, the complex contains a calorimeter. The complex can be equipped with a sensor for monitoring pressure and means for regulating the atmosphere inside the furnace and the working chamber.

The introduction of the condensed decomposition products collection unit installed between the furnace and the sampler into the complex allows the maximum collection of gaseous decomposition products of the analyzed sample and reliable data on the composition of the material from which it is made. The capture unit consists of sequentially installed separators for collecting high-temperature (with a boiling point of 150 ° C and above) and low-temperature (with a boiling point of 50-150 ° C) condensed fractions. After the separators, a sampler of products with a boiling point below 50 ° C is installed. The temperature of the separators is set and controlled using a meter-controller and thermocouples. The presence in the inventive complex of separators with a predetermined temperature thermostating allows you to separate into fractions according to the boiling temperature lying in the selected temperature range, condensed products of thermal decomposition of non-metallic materials and to carry out their further research. This makes it possible to analyze the sample material most fully, without loss of decomposition products. At the same time, the problem of eliminating the ingress of condensed thermal decomposition products into the measuring elements of gas analyzers (as it was in the prototype) is solved, which eliminates the pollution of the system and extends the life of the entire complex. The installation in the working chamber of the furnace of sensors designed to measure the temperature inside the sample and outside the sample or on its surface allows you to measure and control the temperature in order to test calculation methods and simulate thermal processes in large samples. The complex is equipped with a sensor for monitoring pressure and means for regulating the atmosphere inside the furnace and the working chamber, and to determine the specific thermal effect of thermal decomposition, it additionally contains a calorimeter. In the claimed utility model, by combining individual devices (units) into a single measuring complex, we have gained the ability to analyze and study non-metallic materials that are unattainable on standard equipment manufactured in our country and abroad. First of all, this concerns the possibility of working on sufficiently large samples, including the possibility of measuring the temperature distribution inside the sample and controlling the pressure and atmosphere inside the working chamber in which the thermal decomposition process takes place. The information obtained in this case is necessary for testing calculation methods and subsequent forecasting and modeling of the development of combustion on a large scale.

To carry out experimental studies of the behavior of macro samples of polymeric materials in a fire condition, the available standard equipment, including a SETARAM thermal analyzer, a DSK-500 differential scanning calorimeter, various gas analyzers, an analytical balance, etc., was supplemented by a specialized stand, which was specially designed and manufactured.

The resulting complex for studying the processes of thermal decomposition of non-metallic material KITNM (see Figure 1, Figure 2) is designed to study the processes of thermal decomposition under controlled high-temperature effects on both small-scale and rather large-sized samples of polymeric materials and even fragments of products from non-metallic material .

Figure 1 shows a schematic diagram of the claimed complex, and figure 2 is an external view of the central part of the complex, including a furnace, a gas module with gas analyzers and a control panel of the complex.

One of the main elements of the claimed complex is a working chamber (reactor) 1 made of stainless steel with a volume of ~ 5 l, in which the process of thermal decomposition of material samples takes place. A sample of the test material preliminarily weighed on the scales is placed on a special substrate 2, after which the reactor is placed in the furnace 3, where it is heated to a given temperature at a given rate. The “Ceramics” resistance electric furnace used for heating provides programmable heating up to 1000 ° C with a heating rate that can be set in the range of 1-100 ° C / min.

Three thermocouples are installed in the reactor. One of the thermocouples 4 is located directly on the surface of the sample, the other 5 inside it, to measure the temperature distribution in the sample, and with the help of the third thermocouple 6 the temperature is measured in the reactor volume outside the sample, as shown in Fig. 1. Such measurements are necessary, in particular, for testing and testing methods for calculating unsteady temperature fields inside large-scale polymer samples when they are heated.

A pressure sensor 7 is connected to the reactor via a cooled pipeline. As a result, the temperature and pressure are continuously recorded inside the reactor, providing constant monitoring of thermal decomposition of materials.

The design of the complex allows experiments in vacuum, an atmosphere of air or an inert gas, as well as mixing gases in various proportions, obtaining an atmosphere of a given initial composition. For this, air is pumped out of the reactor using a vacuum pump 8. Then the reactor is filled with the required gas from the cylinders 9 using electro-pneumatic valves 10, rotameters 11 and the mixer 12. When mixing two different gases, their concentration at the inlet to the reactor 1 is controlled using a gas chromatograph 13.

If in the reactor during the experiment the pressure is reached above the limit, then it is released through the safety valve 14. The gas generated and released during heating of the sample through pipelines enters the gas module, designed for sampling liquid and gaseous samples for subsequent analysis on a gas chromatograph 13 or using gas analyzers 15, 16, 17. The module consists of two separators 18 and 18 '(high-temperature and low-temperature), designed for condensation and collection of reaction products, with adjustable and using a meter-controller (TPM) 19 thermostating temperatures, which allows you to separate the products of thermal decomposition into fractions having different boiling points.

One of the separators 18 provides the collection of thermal decomposition products having a boiling point of 150 ° C and above, and the other 18 '- the collection of products with a boiling point of 50-150 ° C. The temperature of the separators is set and controlled using a meter-controller (TPM) 19 and thermocouples 20, 21. The gas sampler 23 located after the filter 22 ensures the collection of products with a boiling point below 50 ° C.

In addition to gas chromatograph 13, it is possible to use the available API M200A 15 chemiluminescent gas oxides analyzer, API M101 16 fluorescence gas analyzer and Bruel & Kjer 17 multi-gas monitor to analyze the gas phase. You can take samples for gas analysis at any time during the heating process. Depending on the requirements of the customer (the goals of researching materials), it is possible to analyze products immediately after their isolation, using the data of thermogravimetric analysis previously carried out on a thermal analyzer 24 or after cooling, thereby simulating the gas environment inside a non-metallic material product after a fire and subsequent cooling. Through the discharge system 25, gaseous products are released into the environment.

At any time, the test sample can also be removed from the furnace to determine changes in its mass, density, heat capacity, and mechanical properties. The operation of the complex is controlled from the remote control 26, all data through the controller 27 is sent to a computer, where it is processed and analyzed.

Examples of the implementation of the claimed utility model.

Example 1. The study of the thermal decomposition of a sample of polystyrene. First, a thermogravimetric experiment with a small (~ 38 mg) sample was carried out on a SETARAM thermal analyzer to determine the temperature limits of thermal decomposition. Experience showed that the decomposition of the sample began at a temperature of ~ 293 ° C, at a temperature of 402 ° C 50% of the mass evaporated. sample, and thermal decomposition was almost completed at 445 ° C. A large sample was taken for further experiments. A large-scale sample of polystyrene was a flat opaque cylinder with a diameter of 100 mm and a height of 50 mm. Heating was carried out in an air atmosphere at a rate of 5 ° C / min from room temperature to 450 ° C. The temperature was continuously recorded in the working chamber (reactor), on the surface of the sample and in its volume, for which a thermocouple was introduced into the region coinciding with the geometric center of the sample.

After heating, at the bottom of the low-temperature separator 18 '(thermostating temperature was 50 ° C), condensate formed - a viscous, bright and transparent liquid. Chromatographic analysis of the resulting condensate (liquid) showed that it is 95% of the mass. consists of styrene. The remaining 5% of the mass. accounted for oxygen (10.5% vol.), nitrogen (41% vol.), carbon dioxide and lower hydrocarbons (methane, ethylene, etc.).

Example 2. The study of the thermal decomposition of a sample of polypropylene. Initially, a combined thermogravimetric and differential thermal analysis (TG-DTA experiment) was conducted on a SETARAM thermal analyzer with a small (~ 21 mg) sample. Heating was carried out in a stream of air to a temperature of 700 ° C. Intensive thermal decomposition and the associated decrease in the mass of the sample began at a temperature of 320 ° C and reached a maximum intensity at a temperature of 406 ° C. Thermal decomposition almost ended when the temperature reached ~ 500 ° C. The mass of the ash residue was 9% of the mass. During the heating process, a melting of polypropylene was observed on the DTA curve, proceeding in the range from 154 ° C to 185 ° C, while the mass of the sample did not change, and the measured specific heat of fusion was 67 J / g. With further heating, the processes of thermal degradation and thermal decomposition associated with oxidation (combustion) and heat generation were observed. The total measured heat of the processes is 3.25 kJ / g.

A large sample was taken for further experiments. The sample was a flat opaque cylinder with a diameter of 80 mm and a height of 50 mm. Heating was carried out at a rate of ~ 5 ° C / min from room temperature to 500 ° C in an air atmosphere. The temperature was continuously recorded in the working chamber (reactor), on the surface of the sample and in its volume, for which a thermocouple was introduced into the region coinciding with the geometric center of the sample. Table 1 presents the results of temperature measurements at various points (in the furnace, in the reactor, on the surface and inside the sample).

Table 1. Temperature measurement results at various points The time from the start of the experiment, min Oven temperature, ° C Temperature in the working chamber (reactor), ° C Temperature on the surface of the sample, ° C Temperature in the center of the sample, ° C 0 27 26 25 27 5 38 27 25 26 10 56 32 31 29th fifteen 75 47 45 42 twenty 98 64 63 54 25 127 93 94 75 thirty 163 131 129 115 35 189 161 150 128 40 218 192 163 144 45 247 215 175 154 fifty 273 240 199 181 55 296 267 232 226 60 322 293 262 263 From the table we see a delay in the temperature increase on the sample, observed at temperatures of 150-180 ° C, which is explained by the melting of the sample.

Example 3. The study of the process of thermal decomposition of a sample of polymethyl methacrylate.

Preliminary thermogravimetric analysis on SETARAM showed that the thermal decomposition of polymethylmethacrylate begins at a temperature of 150 ° C, reaches a maximum intensity at 304 ° C, and ends at ~ 400 ° C. The large sample was a round plate with a diameter of 100 mm and a thickness of 20 mm. The sample was heated and kept at 400 ° C for 2 hours, and then the products of thermal decomposition were studied. Some of the decomposition products (16% wt.) Condensed at the bottom of the low-temperature separator 18 '(thermostating temperature was 50 ° C). The analysis showed that the studied condensate consists of methyl methacrylate, which is a monomer of polymethyl methacrylate, at 92%.

Table 2 presents the results of the analysis of the gas phase from gas samplers.

Table 2. The composition of the gas mixture resulting from the heating of polymethyl methacrylate No. p / p Gas phase component Content, vol.% one. Oxygen 37.1 2. Nitrogen 19.6 3. Carbon monoxide 1.4 four. Carbon dioxide 3.5 5. Methane 0.27 7. Ethylene 0.17 8. Propylene + Propane 0.03 9. Water 2.0 10. Methyl methacrylate and other components 35.9

Thus, one of the main components of the gas phase, as well as in the condensate, is the monomer methyl methacrylate.

The inventive complex is a powerful analytical complex for studying the thermal decomposition and thermal decomposition of non-metallic materials in conditions simulating a fire, and is a useful tool in the development of calculation methods, the development of standards and ensuring fire safety when using non-metallic materials in industry, construction and in everyday life.

Claims (4)

1. A complex for studying the processes of thermal decomposition of non-metallic material, comprising a furnace for decomposing a sample of material with a temperature unit for monitoring and programmable task of changing the temperature inside the furnace, a sampler for collecting gaseous decomposition products and units of apparatus for controlling gas flows and analysis of decomposition products, characterized in that it additionally contains a thermal analyzer and a condensate decomposition products capture unit installed between the furnace and the sampler lump for collecting gaseous decomposition products, while the condensed decomposition products collection unit consists of sequentially installed separators for collecting high-temperature and low-temperature condensed fractions with the possibility of controlling the thermostat temperature of the separators, and at least two sensors are installed inside the furnace for measuring temperature inside and outside the sample sample or on its surface. 2. The complex according to claim 1, characterized in that for determining the specific thermal effect of thermal decomposition, it further comprises a calorimeter. 3. The complex according to claim 1, characterized in that it is equipped with a sensor for monitoring pressure inside the furnace and the working chamber. 4. The complex according to claim 1, characterized in that it is equipped with means for regulating the atmosphere inside the furnace and the working chamber.

Images