A method for modifying a belt with a blend of temperature-sensitive materials and a fire warning system for a conveyor belt

Abstract

The present invention relates to the field of coal mine safety, and particularly to a method for modifying a belt with a blended thermosensitive material and a fire warning system for a conveyor belt. During the production process of the conveyor belt, different types of thermosensitive substances are blended with rubber to form a belt covering layer. When the belt is abnormally friction-heated to the pyrolysis temperature of the thermosensitive material, different thermosensitive materials release different characteristic gases. The gas detector monitors the gas concentration and the change in production rate, and transmits the signal to the data processor. The development of the belt fire is judged through the warning model, and different warning messages are issued. The present invention can effectively monitor the conveyor belt in the coal mine underground, timely detect the abnormality of the belt operation, and thus avoid possible fire accidents.

Description

Technical Field

[0001] The present invention relates to the field of coal mine safety, and particularly to a method for modifying a belt with a blended thermosensitive material and a fire warning system for a conveyor belt. Background Art

[0002] Among coal mine external fire accidents, fires caused by conveyor belt ignition account for the vast majority. According to different disaster-causing reasons, belt fires are divided into the following two types: fires caused by belt friction and fires caused by non-belt friction. The former is mainly caused by the belt being stuck, resulting in the active roller slipping completely, and then the belt and the roller rub against each other to catch fire, as well as high-speed friction between the belt conveyor roller and the idler and the belt after mechanical failure; the latter is mainly caused by the overheating of the faulty equipment in a short time after the electrical equipment failure of the belt conveyor, resulting in the belt catching fire, and the spontaneous combustion of the coal on the belt igniting the belt, causing a fire in the belt conveyor.

[0003] In the current belt fire warning systems for monitoring in China, mainly sensing technologies such as CO sensors, smoke sensors, and temperature sensors are used to achieve the monitoring and warning of belt fires. However, due to the influence of the installation position, the temperature sensor cannot achieve the purpose of early prediction of belt fires; CO is also generated during the low-temperature oxidation of coal, resulting in the inability of CO detection to accurately warn of belt fires; when the smoke detection issues an alarm message, the belt has already entered the initial combustion stage. Therefore, the above-mentioned belt fire warning systems cannot accurately warn of the occurrence of belt fires. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for modifying a belt with a blended thermosensitive material and a fire warning system for a conveyor belt, blending different types of thermosensitive substances in the cover layer of the mine conveyor belt on the basis of the original manufacturing process to obtain a belt with a new component cover layer, and at the same time providing a fire warning system including such a belt to solve at least one technical problem in the background art. The adopted technical solution is as follows:

[0005] A method for modifying a belt with a blended thermosensitive material, in which a thermosensitive material is blended in a mine conveyor belt. When the rubber is heated to a molten state, different types of reversibly decomposable thermosensitive materials are added for blending, and then the blended rubber is extruded into the upper and lower cover layers of the belt, and a belt containing thermosensitive substances is formed during the extrusion and cooling process.

[0006] Preferably, the different types of reversibly decomposable thermosensitive materials are one or more solid thermosensitive materials, and the thermosensitive characteristic gas generated by decomposition is a gas that does not exist in the mine.

[0007] Preferably, the thermosensitive materials are ammonium bicarbonate with a decomposition temperature of 50 - 60 °C and iodine bromide with a decomposition temperature of 110 - 120 °C.

[0008] Preferably, the specific method for blending ammonium bicarbonate, iodine bromide with rubber is as follows: ammonium bicarbonate and iodine bromide are separately heated and decomposed. Ammonium bicarbonate decomposes into ammonia, water vapor and carbon dioxide, and iodine bromide decomposes into bromine gas and iodine when heated. Then, the above decomposition products are added into the molten rubber under a pressure of 1 - 3 Mpa and a temperature of 120 - 150 °C, and stirred and blended until uniform. Ammonia, water vapor and carbon dioxide will generate ammonium bicarbonate during the extrusion and cooling process, and bromine gas and iodine will generate iodine bromide during the extrusion and cooling process, which are blended in the upper and lower covering layers of the belt.

[0009] Preferably, the total amount of ammonium bicarbonate and iodine bromide added is 0.1% - 1% of the mass fraction of the rubber in the belt covering layer.

[0010] A fire warning system for a conveyor belt includes a belt prepared by the method of blending a temperature - sensitive material - modified belt as described above, and also includes a characteristic gas detector, a data receiving and processing unit, a zone alarm device, a zone display, a signal bus and a power bus. The characteristic gas detector is connected to the data receiving and processing unit, the data receiving and processing unit is connected to the zone alarm device and the zone display, and the zone alarm device and the zone display are connected to the mine central control system; a warning model is set inside the data receiving and processing unit.

[0011] Preferably, several characteristic gas detectors are included, and one is installed every 30 - 50 meters; each of the characteristic gas detectors can detect the gas generated by the thermal decomposition of the temperature - sensitive material and its concentration change. They are installed on the downwind side of the incoming air in the mine roadway, and are vertically suspended at intervals along the incoming air direction above the head of the belt, 0.3 meters away from the roof of the roadway and 0.2 meters away from the side wall of the roadway in a straight line, and each detector is equipped with a different code.

[0012] Preferably, the warning model is determined according to the decomposition temperature of the temperature - sensitive material, the types and concentration changes of different gases generated by the belt when heated, and is divided into four warning levels, which are: the first level, ammonia is detected, and the temperature range is 50 - 90 °C; the second level, on the basis of the first level, the ratio of CO2 / CO is detected to be 3, and the temperature range is 90 - 110 °C; the third level, on the basis of the first and second levels, bromine or C2H4 is detected, and the temperature range is 110 - 150 °C; the fourth level, on the basis of the first three levels, a rapid increase in C2H4 or soot is detected, and the temperature range is above 150 °C;

[0013] The data receiving and processing unit processes the data transmitted by the characteristic gas detector based on the internal warning model, judges the level of the conveyor - belt fire, and transmits the alarm information to the zone alarm device and the zone display.

[0014] Preferably, after receiving the transmitted alarm information, the area alarm device can display the corresponding belt temperature and gas concentration information, and transmit the early warning information to the mine central control system; the area display is connected to the area alarm device, and the detector code detecting the characteristic gas can be displayed on the area display, so as to accurately locate the abnormal area.

[0015] Preferably, a fire protection module is also provided on the signal bus, which is connected to the mine central control system for input, output, and feedback signals; a bus isolator is provided between the power supply bus and the signal bus.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] The present invention provides a method for modifying a belt with a blend of temperature-sensitive materials, blending different types of temperature-sensitive materials in the cover layer of the mine conveyor belt, and making the temperature-sensitive materials evenly mixed with the upper and lower cover layers of the belt. The belt prepared by this method is applied to the conveyor belt fire early warning system. When the belt temperature is too high, the temperature-sensitive materials in the belt immediately release gas due to the temperature effect, so as to promote an earlier fire early warning time for the belt and a higher prediction accuracy. The system can provide an effective way to accurately judge the location of the fire source and the development of the fire situation for the mine belt fire, thereby reducing the possibility of belt fire caused by abnormal belt operation and greatly improving the safety of the mine. Description of the Drawings

[0018] Figure 1 is a schematic structural diagram of the blending of two temperature-sensitive materials with the belt cover layer;

[0019] Figure 2 is a graph showing the relationship between the concentration of gas released by heating two temperature-sensitive materials of the present invention and the temperature rise;

[0020] Figure 3 is a structural diagram of a conveyor belt fire early warning system of the present invention.

[0021] In the figure: 1, belt; 2, characteristic gas detector; 3, data receiving and processing unit; 4, area alarm device; 5, area display; 6, fire protection module; 7, bus isolator; 8, power supply bus; 9, signal bus. Detailed Embodiments

[0022] The drawings are only for illustrative purposes; it should be understood that the following cases are only used to explain the present invention, which is for the convenience of describing the present invention and simplifying the description. Therefore, it cannot be construed as a limitation of the present invention.

[0023] The principles and features of the present invention will be described below in conjunction with embodiments. The embodiments are only used to explain the present invention and are not intended to limit the scope of the present invention. For those conditions not specified in the embodiments, they shall be carried out according to conventional conditions or the conditions recommended by the manufacturer. For the reagents or instruments whose manufacturers are not indicated, they are all conventional products that can be obtained through commercial purchase.

[0024] The present invention will be further described below in conjunction with embodiments and the accompanying drawings.

[0025] Example 1

[0026] Implementation background: A certain mine plans to install a conveyor belt with a transportation capacity requirement of 1200 t / h. The main motor with a power of 4 * 200 kw is used as the driving device. The conveyor belt has a width of 1200 mm and a strength of 1000 KN / mm. A method of modifying the belt with a blend of thermosensitive materials in the present invention is proposed to prepare the belt and apply it to the fire warning system of the conveyor belt. The specific steps are as follows:

[0027] As Figure 1 shown, the covering layer components of the PVG1250S type conveyor belt used in this roadway are improved, and a thermoplastic elastomer is selected as the rubber for the covering layer. First, the thermosensitive materials ammonium bicarbonate and iodine bromide are heated and decomposed respectively. Ammonium bicarbonate decomposes into ammonia, water vapor and carbon dioxide, and iodine bromide decomposes into bromine gas and iodine when heated. Then, the above decomposition products are added to the molten rubber under a pressure of 3 Mpa and a temperature of 120 °C, and stirred and blended. It is mixed at room temperature for 5 min at a mixing speed of 375 r / min to make it evenly mixed. Ammonia, water vapor and carbon dioxide will form ammonium bicarbonate during the extrusion and cooling process, and bromine gas and iodine will form iodine bromide during the extrusion and cooling process. Among them, the total amount of ammonium bicarbonate and iodine bromide added is 0.5% of the mass fraction of the rubber in the belt covering layer.

[0028] Finally, the covering layer is bonded to the plasticized belt core to make the improved new mine conveyor belt of the present invention.

[0029] Furthermore, a drum friction test is carried out on the new component mine conveyor belt with the improved composition to determine the gas release rate at different actual temperature stages, and then an early warning model is established. As Figure 2 shown in the figure of the relationship between the concentration of the gas released by heating the two thermosensitive materials and the temperature rise, it can be seen from the figure that ammonia is released when the temperature is about 60 °C, and bromine gas is released when the temperature is about 110 °C, indicating that the belt prepared by the method of blending thermosensitive materials meets the requirements of releasing gas at different temperatures.

[0030] As Figure 3As shown in the figure, a belt prepared by the method of blending temperature-sensitive materials is used in the mine roadway, and a fire warning system for the conveyor belt is established. The system uses the belt 1 prepared by the method of blending temperature-sensitive materials, and also includes a characteristic gas detector 2, a data receiving and processing unit 3, a regional alarm device 4, a regional display 5, a signal bus 9 and a power bus 8. The characteristic gas detector 2 is connected to the data receiving and processing unit 3, the data receiving and processing unit 3 is connected to the regional alarm device 4 and the regional display 5, and the regional alarm device 4 and the regional display 5 are connected to the mine central control system; an early warning model is set inside the data receiving and processing unit 3. In the connection of this application, according to actual needs, some are connected by connecting wires, and some are connected by wireless data signals.

[0031] One characteristic gas detector 2 is set every 30 meters, and they are respectively installed on the downwind side of the incoming air in the mine roadway. They are vertically suspended at intervals along the incoming air direction above the head of the belt, 0.3 meters from the top of the roadway and 0.2 meters from the side wall of the roadway in a straight line. Each detector is equipped with a different code, and the signal sent by which characteristic gas detector 2 can be displayed and processed on the regional display 5, and finally the mine central control system can also receive it.

[0032] The early warning model is determined according to the decomposition temperature of the temperature-sensitive material, the types and concentration changes of different gases generated by the belt when heated, and is divided into four levels of early warning, namely: the first level, ammonia is detected, and the temperature range is 50-90 °C; the second level, on the basis of the first level, the ratio of CO2 / CO is detected to be 3, and the temperature range is 90-110 °C; the third level, on the basis of the first and second levels, bromine or C2H4 is detected, and the temperature range is 110-150 °C; the fourth level, on the basis of the first three levels, a rapid increase in C2H4 is detected or soot is detected, and the temperature range is above 150 °C;

[0033] The data receiving and processing unit 3 processes the data transmitted by the characteristic gas detector based on the internal early warning model, judges the level of the conveyor belt fire, and transmits the alarm information to the regional alarm device 4 and the regional display 5.

[0034] After receiving the transmitted alarm information, the regional alarm device 4 can display the corresponding temperature of the belt 1 and gas concentration information, and transmit the early warning information to the mine central control system; the regional display 5 is connected to the regional alarm device 4, and the code of the detected characteristic gas detector 2 can be displayed on the regional display 5, so as to accurately locate the abnormal area.

[0035] For greater safety, a fire protection module 6 is also provided on the signal bus 9, which is connected to the mine central control system for input, output and feedback signals; a bus isolator 7 is provided between the power bus 8 and the signal bus 9 to avoid line crossing and sticking.

[0036] The working process of the above-mentioned conveyor belt fire warning system is as follows: When the abnormal working condition of belt 1 causes the belt to heat up, the temperature-sensitive solid materials ammonium bicarbonate and iodine bromide in belt 1 are decomposed by heat respectively. When the temperature is about 60°C, ammonia gas is released. When the temperature is about 110°C, bromine gas is released. The characteristic gas detector 2 detects the gas and the change of gas concentration, and transmits the data to the data acquisition and processing center. Then, the occurrence and development of belt fire are judged through the built-in warning model, and different alarm levels are issued according to the actual situation, so as to ensure the safety of the mine.

[0037] Example 2

[0038] Improve the composition of the cover layer of the PVG1250S type conveyor belt used in this roadway, and select thermoplastic elastomer as the rubber of the cover layer. First, heat and decompose the temperature-sensitive materials ammonium bicarbonate and iodine bromide respectively. Among them, ammonium bicarbonate decomposes into ammonia gas, water vapor and carbon dioxide, and iodine bromide decomposes into bromine gas and iodine when heated. Then, add the above decomposition products into the molten rubber under the pressure of 2 Mpa and the temperature of 130°C, stir and blend, and mix at normal temperature for 10 min with a mixing speed of 400 r / min to make it evenly mixed. Ammonia gas, water vapor and carbon dioxide will generate ammonium bicarbonate during the extrusion and cooling process, and bromine gas and iodine will generate iodine bromide during the extrusion and cooling process. Among them, the total amount of ammonium bicarbonate and iodine bromide added is 1% of the mass fraction of the belt cover layer rubber.

[0039] One characteristic gas detector 2 is set at intervals of 50 meters, and they are respectively installed on the downwind side of the incoming air in the mine roadway. They are vertically suspended at intervals along the incoming air direction above the head of the belt, 0.3 meters away from the roof of the roadway and 0.2 meters away from the side wall of the roadway in a straight line. Each detector is equipped with a different code, and the signal sent by which characteristic gas detector 2 can be displayed and processed on the area display, and finally the mine central control system can also receive it.

[0040] Other places not mentioned are the same as in Example 1.

[0041] Example 3

[0042] Improve the composition of the covering layer of the PVG1250S type conveyor belt used in this roadway, and select thermoplastic elastomer as the rubber for the covering layer. First, heat and decompose the temperature-sensitive materials ammonium bicarbonate and iodine bromide respectively. Among them, ammonium bicarbonate decomposes into ammonia, water vapor and carbon dioxide, and iodine bromide decomposes into bromine gas and iodine when heated. Then, add the above decomposition products into the molten rubber under the pressure of 2 Mpa and the temperature of 140 °C, stir and blend, mix at room temperature for 8 min, and the mixing speed is 390 r / min to make it evenly mixed. Ammonia, water vapor and carbon dioxide will generate ammonium bicarbonate during the extrusion and cooling process, and bromine gas and iodine will generate iodine bromide during the extrusion and cooling process. Among them, the total amount of ammonium bicarbonate and iodine bromide added is 0.8% of the mass fraction of the rubber in the belt covering layer.

[0043] One characteristic gas detector 2 is set every 40 meters, and they are respectively installed on the downwind side of the incoming air of the mine roadway. They are vertically suspended at intervals along the incoming air direction from above the machine head, 0.3 meters away from the roof of the roadway and 0.2 meters away from the side wall of the roadway in a straight line. And each detector is equipped with a different code. The signal sent by which characteristic gas detector 2 can be displayed and processed on the area display 5, and finally the mine central control system can also receive it.

[0044] Other places not mentioned are the same as in Embodiment 1.

[0045] Embodiment 4

[0046] Improve the composition of the covering layer of the PVG1250S type conveyor belt used in this roadway, and select thermoplastic elastomer as the rubber for the covering layer. First, heat and decompose the temperature-sensitive materials ammonium bicarbonate and iodine bromide respectively. Among them, ammonium bicarbonate decomposes into ammonia, water vapor and carbon dioxide, and iodine bromide decomposes into bromine gas and iodine when heated. Then, add the above decomposition products into the molten rubber under the pressure of 1 Mpa and the temperature of 150 °C, stir and blend, mix at room temperature for 5 min, and the mixing speed is 380 r / min to make it evenly mixed. Ammonia, water vapor and carbon dioxide will generate ammonium bicarbonate during the extrusion and cooling process, and bromine gas and iodine will generate iodine bromide during the extrusion and cooling process. Among them, the total amount of ammonium bicarbonate and iodine bromide added is 0.8% of the mass fraction of the rubber in the belt covering layer.

[0047] One characteristic gas detector 2 is set every 30 meters, and they are respectively installed on the downwind side of the incoming air of the mine roadway. They are vertically suspended at intervals along the incoming air direction from above the machine head, 0.3 meters away from the roof of the roadway and 0.2 meters away from the side wall of the roadway in a straight line. And each detector is equipped with a different code. The signal sent by which characteristic gas detector 2 can be displayed and processed on the area display 5, and finally the mine central control system can also receive it.

[0048] Other places not mentioned are the same as in Embodiment 1.

[0049] Those of ordinary skill in the art will realize that the experimental examples shown here are for helping readers understand the principles of the present invention, and it should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those of ordinary skill in the art can make various other deformations in other aspects that do not deviate from the essence of the present invention according to these technical revelations disclosed by the present invention, and these deformations are still within the protection scope of the present invention.

Claims

1. A method for modifying a belt with a blended thermosensitive material, which involves blending the thermosensitive material in a mine transportation belt, characterized in that, Heat the rubber to a molten state, add different types of thermosensitive materials that can reversibly decompose for blending, and then extrude the blended rubber into the upper and lower cover layers of the belt. During the extrusion and cooling process, a belt containing thermosensitive substances is formed. The thermosensitive materials are ammonium bicarbonate with a decomposition temperature of 50 - 60 °C and iodine bromide with a decomposition temperature of 110 - 120 °C. The specific method of blending ammonium bicarbonate, iodine bromide with rubber is as follows: Heat and decompose ammonium bicarbonate and iodine bromide respectively. Ammonium bicarbonate decomposes into ammonia, water vapor and carbon dioxide, and iodine bromide decomposes into bromine gas and iodine when heated. Then, add the above decomposition products into the molten rubber under a pressure of 1 - 3 Mpa and a temperature of 120 - 150 °C, and stir and blend until uniform. Ammonia, water vapor and carbon dioxide will form ammonium bicarbonate during the extrusion and cooling process, and bromine gas and iodine will form iodine bromide during the extrusion and cooling process, which are blended in the upper and lower cover layers of the belt.

2. The method for modifying a belt with a blended thermosensitive material according to claim 1, characterized in that, The total amount of ammonium bicarbonate and iodine bromide added is 0.1% - 1% of the mass fraction of the rubber in the belt cover layer.

3. A fire warning system for a transportation belt, characterized in that, It includes a belt prepared by the method of modifying a belt with a blended thermosensitive material according to any one of claims 1 or 2, and also includes a characteristic gas detector, a data receiving and processing unit, a regional alarm device, a regional display, a signal bus and a power bus. The characteristic gas detector is connected to the data receiving and processing unit, the data receiving and processing unit is connected to the regional alarm device and the regional display, and the regional alarm device and the regional display are connected to the mine central control system; a warning model is set inside the data receiving and processing unit.

4. The fire warning system for a transportation belt according to claim 3, characterized in that, There are several characteristic gas detectors, one is installed every 30 - 50 meters; each of the characteristic gas detectors can detect the gases generated by the thermal decomposition of the thermosensitive material and their concentration changes. They are installed on the downwind side of the incoming air in the mine roadway, and are vertically suspended at intervals along the incoming air direction above the head of the belt, 0.3 meters away from the roof of the roadway and 0.2 meters away from the side wall of the roadway in a straight line, and each detector is equipped with a different code.

5. The fire warning system for a transportation belt according to claim 3, characterized in that, The warning model is determined according to the decomposition temperature of the thermosensitive material, the types and concentration changes of different gases generated by the belt when heated, and is divided into four levels of warning grades, which are: The first level, ammonia is detected, and the temperature range is 50 - 90 °C; The second level, on the basis of the first level, the ratio of CO2 / CO is detected to be 3, and the temperature range is 90 - 110 °C; The third level, on the basis of the first and second levels, bromine or C2H4 is detected, and the temperature range is 110 - 150 °C; The fourth level, on the basis of the first three levels, a rapid increase in C2H4 is detected or soot is detected, and the temperature range is above 150 °C. The data receiving and processing unit processes the data transmitted by the characteristic gas detector based on the internal warning model, judges the grade of the belt fire, and transmits the alarm information to the regional alarm device and the regional display.

6. The fire warning system for a transportation belt according to claim 5, characterized in that, After receiving the transmitted alarm information, the regional alarm device can display the corresponding belt temperature and gas concentration information, and transmit the warning information to the mine central control system; the regional display is connected to the regional alarm device, and the code of the characteristic gas detector that detects the characteristic gas can be displayed on the regional display.

7. The fire warning system for a transportation belt according to claim 3, characterized in that, A fire protection module is also provided on the signal bus; a bus isolator is provided between the power bus and the signal bus.

Images