CN114397323A - Device and method for measuring shortest natural ignition period of coal - Google Patents
Device and method for measuring shortest natural ignition period of coal Download PDFInfo
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- CN114397323A CN114397323A CN202111524031.3A CN202111524031A CN114397323A CN 114397323 A CN114397323 A CN 114397323A CN 202111524031 A CN202111524031 A CN 202111524031A CN 114397323 A CN114397323 A CN 114397323A
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Abstract
The invention belongs to the technical field of coal spontaneous combustion period determination, and particularly provides a laboratory determination device and a laboratory determination method for the shortest spontaneous combustion period of coal. A device for measuring the shortest natural ignition period of coal mainly comprises a dry gas source, an oil storage tank, an oil pump, an oxidation furnace, a gas guide pipe, an oil guide pipe, a temperature sensor, a data acquisition unit and a computer; the method for measuring the shortest spontaneous combustion period of the coal comprises the following steps: sampling coal bed coal; preparing and managing a coal sample; measuring the ignition temperature of the coal sample; checking the equipment state, and loading a coal sample in the checking process; starting a gas circuit and an oil circuit of the equipment, and measuring and collecting air temperature, oil temperature and coal temperature data; and performing operation processing on the recorded data to obtain the shortest natural ignition period result of the coal sample. The heat balance system of the coal oxidation self-heating process is constructed by adopting vacuum heat insulation, circulating oil bath and self-adaptive heating modes, the problem that heat dissipation and environment temperature are uncontrollable is solved, and the experimental process has repeatability and high reliability.
Description
Technical Field
The invention belongs to the technical field of coal spontaneous combustion period determination, and particularly provides a laboratory determination device and a laboratory determination method for the shortest spontaneous combustion period of coal.
Background
The time from the time the coal body contacts the air to the time spontaneous combustion begins to occur is called the natural ignition period of the coal. The coal natural ignition period is a measurement of coal spontaneous combustion risk in time, is an important index for evaluating the coal natural ignition risk and is an important parameter for guiding the field production of a coal mine.
The prediction of the earliest natural fire period is roughly estimated mainly by experience and field statistics, and generally takes months as a unit, so that the field work cannot be effectively guided. Therefore, natural ignition experiment tables are adopted by various countries to simulate the natural ignition process of coal, the natural ignition period of the coal is further predicted, basic data are provided for the fire prevention and extinguishing work of a coal mine site, and a good effect is obtained.
The traditional coal spontaneous combustion experiment table approximately simulates the field heat dissipation condition, the air leakage condition and the float coal thickness, takes the room temperature as the experiment starting temperature, utilizes the coal oxidation heat release to cause the natural temperature rise, and continuously monitors the temperature of each characteristic point in the coal body and the change condition of gas components, thereby researching the oxidation heat release characteristic of the coal and predicting the spontaneous combustion period of the coal. Since the natural ignition period of coal is several months and ten or more days, and the experimental process has a possibility of failure, there is a problem that the time and economic cost are too high in both the measurement work for research and the measurement work for experimental analysis. Therefore, a laboratory measuring scheme for the natural ignition period of the coal, which has the advantages of short experimental period, repeatability and high reliability and can truly restore the natural ignition process, is needed.
Disclosure of Invention
In order to solve the problems, the invention provides a laboratory measuring device and a measuring method for the shortest spontaneous combustion period of coal.
In order to achieve the purpose, the invention adopts the technical scheme that: the utility model provides a survey device of shortest spontaneous combustion period of coal, including dry air supply, the batch oil tank, the oil pump, the oxidation furnace, the air duct, lead oil pipe, a weighing sensor and a temperature sensor, data collection station, a computer, dry air supply passes through the air duct to be connected with the gas circuit of batch oil tank, the gas circuit of batch oil tank is connected through the air duct and is connected with the gas circuit of oxidation furnace, the oil circuit of batch oil tank is connected through the oil duct that leads with the oil circuit of oxidation furnace, the oil pump sets up in the middle part of leading oil pipe, the inside of oxidation furnace is provided with temperature sensor, temperature sensor passes through data collection station and computer electric connection, the computer pass through the data line respectively with the batch oil tank, oil pump electric connection.
Furthermore, the oil storage tank comprises a tank body, a stirrer, a spiral heating pipe, an oil return pipe, an oil outlet pipe and an electric heater, the stirrer is assembled in the middle of the top cover of the tank body, and the blades of the stirrer extend to the bottom of the inner cavity of the box body, the spiral heating pipe is assembled in the box body, and the inlet end and the end of giving vent to anger of spiral heating pipe extend to the box outside, return oil pipe, go out the top cap that oil pipe runs through the box, the end that returns oil pipe extends to the top of box inner chamber, the end that goes out oil pipe extends to the bottom of box inner chamber, electric heater assembles in the inside of box, dry air supply and the inlet end intercommunication of spiral heating pipe, the gas circuit of oxidation oven and the end intercommunication of giving vent to anger of spiral heating pipe, return oil pipe is through the oil pipe and the oil return pipeline intercommunication of oxidation oven, go out oil pipe and the oil inlet pipeline intercommunication of oxidation oven, and the oil pump sets up in the oil inlet pipeline of oxidation oven, electric heater and computer electric connection.
Further, the oxidation furnace comprises a furnace body, a vacuum cavity, an oil bath cavity, a reaction chamber, support nets, an air inlet pipe interface, a spiral air guide pipe, an air outlet pipe interface, an oil return pipe interface and an oil inlet pipe interface, wherein the vacuum cavity and the oil bath cavity are both arranged in the furnace wall of the furnace body, the vacuum cavity is wrapped outside the oil bath cavity, the reaction chamber is a furnace chamber in the furnace body, the two support nets are respectively assembled at the top and the bottom of the reaction chamber, the air inlet pipe interface and the air outlet pipe interface are arranged on the top cover of the furnace body, the spiral air guide pipe is arranged in the reaction chamber, the air inlet end of the spiral air guide pipe is communicated with the air inlet pipe interface, the air outlet end of the spiral air guide pipe extends to the bottom of the reaction chamber, the air outlet pipe interface is communicated with the reaction chamber, the oil return pipe interface is arranged at the top of the side wall of the furnace body, the oil inlet pipe interface is arranged at the bottom wall of the furnace body, the oil return pipe interface and the oil return pipe interface are communicated with the oil return pipe through an oil guide pipe, the oil inlet pipe interface is communicated with an oil inlet pipeline through an oil guide pipe.
Furthermore, the temperature sensor comprises an oil bath cavity platinum resistor I, an oil bath cavity platinum resistor II, an oil bath cavity platinum resistor III, an oil bath cavity platinum resistor IV, an oil bath cavity platinum resistor V, a reaction chamber platinum resistor and a reaction chamber platinum resistor II, the oil bath cavity platinum resistor I and the oil bath cavity platinum resistor II are respectively arranged at the opposite side positions of the middle part of the inner side wall of the oil bath cavity, the oil bath cavity platinum resistor III is arranged at the inner wall of the oil inlet pipe interface, the oil bath cavity platinum resistor IV and the oil bath cavity platinum resistor V are respectively arranged at the inner wall positions of the two oil return pipe interfaces, the reaction chamber platinum resistor I and the reaction chamber platinum resistor II are respectively arranged at the opposite side positions of the middle part of the inner side wall of the reaction chamber, the reaction chamber platinum resistor III is arranged at the middle part of the bottom wall of the reaction chamber, the reaction chamber platinum resistor IV is arranged at the inner wall position of the air outlet pipe interface, and the nine platinum resistors are electrically connected with the data collector.
The device further comprises a liquid flow meter, stop valves, a pressure reducing valve, a pressure stabilizing valve and a flow controller, wherein the liquid flow meter is assembled in an oil inlet pipeline of the oxidation furnace, the two stop valves are respectively assembled at the external interfaces of the oil return pipe and the oil outlet pipe, the pressure reducing valve, the pressure stabilizing valve and the flow controller are sequentially assembled on an air guide pipe outside a dry air source, and the stop valves and the flow controller are respectively and electrically connected with a computer.
A method for measuring the shortest spontaneous combustion period of coal comprises the following steps:
step 1, taking a coal bed coal sample;
step 3, measuring the ignition temperature of the coal sample;
and 6, performing operation processing on the recorded data to obtain the shortest natural ignition period result of the coal sample.
Furthermore, in step 2, the processing flow of the preparation and management of the coal sample is based on the regulation related to GB474, and should meet the following requirements:
1) when the water content of the coal sample is high and the subsequent experiment is influenced, the coal sample is naturally dried, and then all the coal samples are crushed to be less than 10 mm;
2) dividing the coal sample to 300-350 g by a cone stacking quartering method for preparing and analyzing the coal sample, and sealing the rest coal samples according to the original package to serve as the stored and searched coal sample;
3) the pulverized coal sample was stored in a jar under sealed conditions and each measurement was completed within 30 days.
Further, in step 4, the flow of equipment state inspection and coal sample loading is as follows:
1) checking the air tightness of the air passage, the oil passage and the vacuum cavity of the oxidation furnace, wherein the vacuum degree of the vacuum cavity of the oxidation furnace is not lower than 100 kPa;
2) checking the running states of the temperature sensor, the gas flow controller, the liquid flowmeter and the data acquisition unit, and debugging the existing problems;
3) after the air tightness is confirmed and various related instruments run normally, 100 +/-0.1 g of coal sample to be detected is loaded into the reaction chamber;
4) after the sample is filled, the air tightness of the instrument is checked again.
Further, in step 5, the gas circuit and the oil circuit of the equipment are started, and the flow of collecting the air temperature, the oil temperature and the coal temperature data is measured as follows:
1) introducing dry air into the reaction chamber at a stable flow of 300mL/min, setting the temperature of the oil bath cavity at 40 ℃, and stabilizing the flow of the heat transfer oil at 10L/min;
2) when the temperature of the coal sample is stable, recording and calculating the temperature of the coal sample at 40 ℃ of the oil bath cavity
Temperature difference between oil inlet and oil return
Temperature difference with air inlet and outlet
3) Setting the temperature of the oil bath cavity to 1.0 ℃/min for temperature programming, starting a data acquisition unit to acquire data such as air flow, air temperature of inlet and outlet air, heat conduction oil flow, oil inlet and return temperature, oil bath temperature, coal sample temperature and the like;
4) when the temperature of the coal sample collected by the data collector exceeds the temperature of the inlet of the oil bath cavity, setting the temperature of the oil bath cavity to be maintained at the current temperature;
5) stopping data acquisition after the temperature of the coal sample is stable, recording and calculating the temperature of the coal sample
Temperature difference between oil inlet and oil return
Temperature difference with air inlet and outlet
Further, in step 6, the data processing operation steps are as follows:
calculating step of shortest natural ignition period of coal
1) Calculating the coal chemical reaction rate parameter ka
2) Calculating the shortest spontaneous combustion period tau of the coal, wherein the unit is day (d):
shortest spontaneous combustion period of coal τ:
the beneficial effects of the invention are as follows:
1. the measuring device adopts a vacuum heat insulation, circulating oil bath and self-adaptive heating mode to construct a heat balance system in the coal oxidation self-heating process, solves the problem of uncontrollable heat dissipation and environmental temperature, and ensures that the experimental process has repeatability and high reliability;
2. in the process that a worker measures the natural ignition period of coal by using a device for measuring the shortest natural ignition period of coal, a system detects the temperature of oil in an oil bath cavity and the temperature of coal in a reaction chamber in real time through a temperature sensor;
a feedback mechanism is applied in the temperature adjusting process, when the temperature rise rate of the temperature in the reaction chamber is increased along with the increase of the temperature rise rate of the coal sample, the system can synchronously adjust the temperature rise rate of the oil temperature, and the effect of dynamic balance of the temperature and the oil temperature is realized; in the experimental coal sample heating process, the system records the temperature data of each characteristic point through a temperature sensor; when the temperature of the experimental coal sample rises to the coal ignition temperature, substituting the data into a mathematical model established by long-term experimental observation to calculate the natural ignition period of the coal sample; the effect of stabilizing and improving the temperature rise process of the coal body is achieved, and the experimental period is shortened.
Drawings
FIG. 1 is a schematic structural view of the present invention as a whole;
FIG. 2 is a diagram of the connection relationship of the electronic components of the present invention.
The reference numerals include: 1-drying the air source; 2-an oil storage tank; 201-a box body; 202-a stirrer; 203-spiral heating pipe; 204-oil return pipe; 205-an oil outlet pipe; 206-an electric heater; 3-an oil pump; 4-oxidation furnace; 401-furnace body; 402-a vacuum chamber; 403-oil bath cavity; 404-a reaction chamber; 405-a supporting net; 406-inlet pipe interface; 407-helical airway; 408-an outlet pipe interface; 409-oil return pipe interface; 410-oil inlet pipe interface; 5, an air guide pipe; 6-oil guide pipe; 701-oil bath cavity platinum resistor I; 702-oil bath cavity platinum resistor II; 703-oil bath cavity platinum resistor III; 704-oil bath cavity platinum resistor IV; 705-oil bath cavity platinum resistance five; 706-reaction chamber platinum resistor one; 707-reaction chamber platinum resistance two; 708-reaction chamber platinum resistor III; 709-reaction chamber platinum resistance four; 8-a liquid flow meter; 9-a stop valve; 10-a pressure reducing valve; 11-a pressure maintaining valve; 12-a flow controller; 13-a data collector; 14-computer.
Detailed Description
The present invention is described in detail below with reference to the attached drawings.
Referring to fig. 1-2, a device for measuring the shortest natural ignition period of coal comprises a dry gas source 1, an oil storage tank 2, an oil pump 3, an oxidation furnace 4, a gas guide tube 5, an oil guide tube 6, a temperature sensor, a data collector 13 and a computer 14, wherein the dry gas source 1 is connected with a gas circuit of the oil storage tank 2 through the gas guide tube 5, the gas circuit of the oil storage tank 2 is connected with a gas circuit of the oxidation furnace 4 through the gas guide tube 5, the oil circuit of the oil storage tank 2 is connected with a gas circuit of the oxidation furnace 4 through the oil guide tube 6, the oil pump 3 is arranged in the middle of the oil guide tube 6, the temperature sensor is arranged in the oxidation furnace 4, the temperature sensor is electrically connected with the computer 14 through the data collector 13, and the computer 14 is electrically connected with the oil storage tank 2 and the oil pump 3 through data lines respectively.
The oil storage tank 2 comprises a tank body 201, a stirrer 202, a spiral heating pipe 203, an oil return pipe 204, an oil outlet pipe 205 and an electric heater 206, wherein the stirrer 202 is assembled in the middle of a top cover of the tank body 201, blades of the stirrer 202 extend to the bottom of an inner cavity of the tank body 201, the spiral heating pipe 203 is assembled in the tank body 201, an air inlet end and an air outlet end of the spiral heating pipe 203 extend to the outside of the tank body 201, the oil return pipe 204 and the oil outlet pipe 205 penetrate through the top cover of the tank body 201, the tail end of the oil return pipe 204 extends to the top of the inner cavity of the tank body 201, the tail end of the oil outlet pipe 205 extends to the bottom of the inner cavity of the tank body 201, the electric heater 206 is assembled in the tank body 201, a drying air source 1 is communicated with the air inlet end of the spiral heating pipe 203, an air passage of the oxidation furnace 4 is communicated with the air outlet end of the spiral heating pipe 203, the oil return pipe 204 is communicated with an oil return pipeline of the oxidation furnace 4 through an oil guide pipe 6, the oil outlet pipe 205 is communicated with an oil inlet pipeline of the oxidation furnace 4, the oil pump 3 is disposed in the oil inlet pipeline of the oxidation furnace 4, and the electric heater 206 is electrically connected to the computer 14.
Preferably, the mode of monitoring the temperature in the oil storage tank 2 is as follows: the electric heater 206 in the oil storage tank 2 is provided with a matched temperature detection component for detecting the temperature in the oil storage tank 2; or a separate temperature sensor may be provided in the oil reservoir 2 for monitoring the internal temperature thereof.
The electric heater 206 controls the heating rate of heat conducting oil in the box 201, and the heat conducting oil simultaneously heats air circulating in the spiral heating pipe 203.
The oxidation furnace 4 comprises a furnace body 401, a vacuum cavity 402, an oil bath cavity 403, a reaction chamber 404, supporting nets 405, an air inlet pipe connector 406, a spiral air guide pipe 407, an air outlet pipe connector 408, an oil return pipe connector 409 and an oil inlet pipe connector 410, wherein the vacuum cavity 402 and the oil bath cavity 403 are both arranged in the furnace wall of the furnace body 401, the vacuum cavity 402 is wrapped outside the oil bath cavity 403, the reaction chamber 404 is a furnace chamber in the furnace body 401, the two supporting nets 405 are respectively assembled at the top and the bottom of the reaction chamber 404, the air inlet pipe connector 406 and the air outlet pipe connector 408 are arranged on the top cover of the furnace body 401, the spiral air guide pipe 407 is arranged in the reaction chamber 404, the air inlet end of the spiral air guide pipe 407 is communicated with the air inlet pipe connector 406, the air outlet end of the spiral air guide pipe 407 extends to the bottom of the reaction chamber 404, the air outlet pipe connector 408 is communicated with the reaction chamber 404, the oil return pipe connector is arranged at the top of the side wall of the furnace body 401, the oil inlet pipe connector 410 is arranged at the bottom wall of the furnace body 401, and the oil return pipe interface 409 and the oil inlet pipe interface 410 are both communicated with the oil bath cavity 403, the oil return pipe interface 409 is communicated with an oil return pipeline through an oil guide pipe 6, and the oil inlet pipe interface 410 is communicated with an oil inlet pipeline through the oil guide pipe 6.
The vacuum chamber 402 can reduce the speed of heat dissipation inside, reduce the influence of environmental factors on the temperature of the furnace body, and provide buffer time for oil temperature adjustment. The oil bath cavity 403 is a ring of a heat conduction oil circulation path, and the heat conduction oil is used as a medium to adjust the external temperature of the reaction chamber 404, so that the external temperature of the reaction chamber 404 continuously tracks up the internal temperature of the reaction chamber 404 with a very small temperature difference, and a slightly lagging feedback type adjustment stable state is formed. By simultaneously increasing the external temperature, the heat generated spontaneously by the coal in the reaction chamber 404 is prevented from dissipating in a manner that eliminates the temperature difference.
Circulating an oil path: the oil pump comprises a box body 201, an oil outlet pipe 205, an oil pump 3, an oil inlet pipe interface 410, an oil bath cavity 403, an oil return pipe interface 409, an oil guide pipe 6, an oil return pipe 204 and the box body 201.
Gas circuit: the dry gas source 1-gas guide tube 5-spiral heating tube 203-gas inlet tube interface 406-spiral gas guide tube 407-reaction chamber 404-gas outlet tube interface 408-outside.
The temperature of the gas in the gas path is adjusted at the spiral heating pipe 203 and is controlled by the temperature of the heat conducting oil in the box 201, and the temperature of the heat conducting oil is obtained by the system and is measured in the reaction chamber 404, and then the electric heater 206 is controlled to heat and adjust.
Dry air is introduced into the reaction chamber 404 through the air passage, thereby providing an oxidizing environment for the coal sample in the reaction chamber 404. The air in the air path is heated, so that the temperature of the air can be kept consistent with that of the reaction chamber, and the heat of the coal sample is prevented from being taken away in the process of discharging the coal sample by the air, so that the heat loss of the coal sample is avoided.
The temperature sensor comprises an oil bath cavity platinum resistor I701, an oil bath cavity platinum resistor II 702, an oil bath cavity platinum resistor III 703, an oil bath cavity platinum resistor IV 704, an oil bath cavity platinum resistor V705, a reaction chamber platinum resistor I706, a reaction chamber platinum resistor II 707, a reaction chamber platinum resistor III 708 and a reaction chamber platinum resistor IV 709, wherein the oil bath cavity platinum resistor I701 and the oil bath cavity platinum resistor II 702 are respectively arranged at opposite sides of the middle part of the inner side wall of the oil bath cavity 403, the oil bath cavity platinum resistor III 703 is arranged at the inner wall of the oil inlet pipe interface 410, the oil bath cavity platinum resistor IV 704 and the oil bath cavity platinum resistor V705 are respectively arranged at the inner walls of the two oil return pipe interfaces 409, the reaction chamber platinum resistor I706 and the reaction chamber platinum resistor II 707 are respectively arranged at opposite sides of the middle part of the inner side wall of the reaction chamber 404, the reaction chamber platinum resistor III is arranged at the middle part of the bottom wall of the reaction chamber 404, the reaction chamber platinum resistor IV 709 is arranged at the inner wall of the oil outlet pipe interface 408, the nine platinum resistors are all electrically connected with the data acquisition unit 13.
The platinum resistor is a platinum thermal resistor for short, and its resistance value changes with the temperature change, and is a common thermal sensor.
The platinum resistor is arranged at multiple points on the inner wall of the container, so that the effect of multipoint detection of the temperature in the cavity is achieved. The temperature data in the cavity is obtained after comprehensive evaluation and calculation of the temperature data measured by the plurality of detection points, and the data deviation rate caused by the point selection problem is reduced.
The measuring device further comprises a liquid flow meter 8, stop valves 9, a pressure reducing valve 10, a pressure stabilizing valve 11 and a flow controller 12, wherein the liquid flow meter 8 is assembled in an oil inlet pipeline of the oxidation furnace 4, the two stop valves 9 are respectively assembled at the external interfaces of the oil return pipe 204 and the oil outlet pipe 205, the pressure reducing valve 10, the pressure stabilizing valve 11 and the flow controller 12 are sequentially assembled on the air guide pipe 5 outside the dry air source 1, and the stop valves 9 and the flow controller 12 are respectively electrically connected with the computer 14.
Preferably, the optimal shape of the reaction chamber 404 is a cylindrical cylinder with a diameter of 60mm and a height of 60mm, as deduced from lumped parameter theory. The reaction chamber 404 may hold 90g to 120g of a coal sample.
A measuring method using the device for measuring the shortest spontaneous combustion period of the coal comprises the following steps:
step 1, taking a coal bed coal sample;
the standard for sampling coal samples of coal beds is based on the regulation of GB/T482.
the processing flow of the preparation and management of the coal sample is based on the regulation related to GB474, and the following requirements are met at the same time:
1) when the water content of the coal sample is high and the subsequent experiment is influenced, the coal sample is naturally dried, all the coal samples are crushed to be below 10mm, and are reduced to 300-350 g by a stacking cone quartering method for preparing and analyzing the coal sample, and the rest coal samples are packaged and sealed as the stored and checked coal samples;
2) when a coal sample is crushed, 300 g-350 g of coal sample for analysis must be completely crushed to be less than 0.15mm, and the granularity of 0.10 mm-0.15 mm is required to be more than 70%;
3) sealing and storing the crushed coal sample in a wide-mouth bottle, and completing various measurements within 30 days;
4) the coal samples to be checked and the coal samples to be analyzed are stored for 6 months after the analysis report is sent out.
Step 3, measuring the ignition temperature of the coal sample;
the standard for measuring the ignition temperature of the coal sample is based on the regulation of GB/T18511.
the equipment state inspection and coal sample loading process comprises the following steps:
1) checking the air tightness of the air passage, the oil passage and the vacuum cavity of the oxidation furnace, wherein the vacuum degree of the vacuum cavity of the oxidation furnace is not lower than 100 kPa;
2) checking the running states of the temperature sensor, the gas flow controller, the liquid flowmeter and the data acquisition unit, and debugging the existing problems;
3) after the air tightness is confirmed and various related instruments run normally, 100 +/-0.1 g of coal sample to be detected is loaded into the reaction chamber;
4) after the sample is filled, the air tightness of the instrument is checked again.
wherein, the gas circuit and the oil circuit of starting equipment to survey the flow of collecting temperature, oil temperature and coal temperature data as follows:
1) introducing dry air into the reaction chamber at a stable flow of 300mL/min, setting the temperature of the oil bath cavity at 40 ℃, and stabilizing the flow of the heat transfer oil at 10L/min;
2) when the temperature of the coal sample (the unit of the temperature referred to in the text is centigrade (DEG C)) is stable, the temperature of the coal sample under the temperature of 40 ℃ of the oil bath cavity is recorded and calculated
Temperature difference between oil inlet and oil return
(the oil temperature at the oil inlet pipe joint 410 is
The oil temperature of the oil return pipe interface 409 is
) Temperature difference with air inlet and outlet
(air inlet pipe interface 406 temperature is
Outlet duct joint 408 has an air temperature of
)；
3) Setting the temperature of the oil bath cavity to 1.0 ℃/min for temperature programming, starting a data acquisition unit to acquire data such as air flow, air temperature of inlet and outlet air, heat conduction oil flow, oil inlet and return temperature, oil bath temperature, coal sample temperature and the like;
4) when the temperature of the coal sample collected by the data collector exceeds the temperature of the inlet of the oil bath cavity, setting the temperature of the oil bath cavity to be maintained at the current temperature;
5) stopping data acquisition after the temperature of the coal sample is stable, recording and calculating the temperature of the coal sample
Temperature difference between oil inlet and oil return
Temperature difference with air inlet and outlet
the data processing and operation steps are as follows:
calculating step of shortest natural ignition period of coal
1) Calculating the coal chemical reaction rate parameter ka
2) Calculating the shortest spontaneous combustion period tau of the coal, wherein the unit is day (d):
shortest spontaneous combustion period of coal τ:
the measuring device adopts vacuum heat insulation, circulating oil bath and self-adaptive heating modes to construct a heat balance system in the coal oxidation self-heating process.
In the process that a worker determines the natural ignition period of coal by using the shortest natural ignition period determination device of coal, the system detects the oil temperature T in the oil bath cavity 403 in real time through the temperature sensorOil bathThe temperature of the coal in the reaction chamber 404 is TReaction chamber(here two temperature values are obtained by the comprehensive consideration of the multi-point temperature data in each chamber respectively to reduce the data error);
the system adjusts T by controlling the electric heater 206 to adjust the oil temperatureOil bathIn the experimental process, the temperature difference between the oil bath cavity 403 and the reaction chamber 404 is ensured to be more than 0 ℃ and less than delta T and less than 2.5 ℃ (delta T is less than or equal to T)Oil bath-TReaction chamber). A feedback mechanism is applied in the temperature adjusting process, when the temperature rise rate of the temperature in the reaction chamber is increased along with the increase of the temperature rise rate of the coal sample, the system can synchronously adjust the temperature rise rate of the oil temperature, and the effect of dynamic balance of the temperature and the oil temperature is realized;
in the experimental coal sample heating process, the system records the temperature data of each characteristic point through a temperature sensor;
and when the temperature of the experimental coal sample rises to the coal ignition temperature, substituting the data into a mathematical model established by long-term experimental observation to calculate the natural ignition period of the coal sample.
The foregoing is only a preferred embodiment of the present invention, and many variations in the detailed description and the application range can be made by those skilled in the art without departing from the spirit of the present invention, and all changes that fall within the protective scope of the invention are therefore considered to be within the scope of the invention.
Claims (10)
1. A device for measuring the shortest spontaneous combustion period of coal is characterized in that: including dry air supply, the batch oil tank, the oil pump, the oxidation furnace, the air duct, lead oil pipe, temperature sensor, data collection station, the computer, dry air supply passes through the air circuit connection of air duct and batch oil tank, the air circuit connection of batch oil tank passes through the air duct and is connected with the gas circuit of oxidation furnace, the oil circuit connection of batch oil tank is through leading the oil circuit connection of oil pipe and oxidation furnace, the oil pump sets up in the middle part of leading oil pipe, the inside of oxidation furnace is provided with temperature sensor, temperature sensor passes through data collection station and computer electric connection, the computer pass through the data line respectively with the batch oil tank, oil pump electric connection.
2. The apparatus for determining the shortest spontaneous combustion period of coal according to claim 1, wherein: the oil storage tank comprises a tank body, a stirrer, a spiral heating pipe, an oil return pipe, an oil outlet pipe and an electric heater, wherein the stirrer is assembled in the middle of a top cover of the tank body, and the blades of the stirrer extend to the bottom of the inner cavity of the box body, the spiral heating pipe is assembled in the box body, and the inlet end and the end of giving vent to anger of spiral heating pipe extend to the box outside, return oil pipe, go out the top cap that oil pipe runs through the box, the end that returns oil pipe extends to the top of box inner chamber, the end that goes out oil pipe extends to the bottom of box inner chamber, electric heater assembles in the inside of box, dry air supply and the inlet end intercommunication of spiral heating pipe, the gas circuit of oxidation oven and the end intercommunication of giving vent to anger of spiral heating pipe, return oil pipe is through the oil pipe and the oil return pipeline intercommunication of oxidation oven, go out oil pipe and the oil inlet pipeline intercommunication of oxidation oven, and the oil pump sets up in the oil inlet pipeline of oxidation oven, electric heater and computer electric connection.
3. The apparatus for determining the shortest spontaneous combustion period of coal according to claim 1, wherein: the oxidation furnace comprises a furnace body, a vacuum cavity, an oil bath cavity, a reaction chamber, support nets, an air inlet pipe interface, a spiral air guide pipe, an air outlet pipe interface, an oil return pipe interface and an oil inlet pipe interface, wherein the vacuum cavity and the oil bath cavity are both arranged in the furnace wall of the furnace body, the vacuum cavity is wrapped outside the oil bath cavity, the reaction chamber is a furnace chamber in the furnace body, the two support nets are respectively assembled at the top and the bottom of the reaction chamber, the air inlet pipe interface and the air outlet pipe interface are arranged on the top cover of the furnace body, the spiral air guide pipe is arranged in the reaction chamber, the air inlet end of the spiral air guide pipe is communicated with the air inlet pipe interface, the air outlet end of the spiral air guide pipe extends to the bottom of the reaction chamber, the air outlet pipe interface is communicated with the reaction chamber, the oil return pipe interface is arranged at the top of the side wall of the furnace body, the oil inlet pipe interface is arranged at the bottom wall of the furnace body, the oil return pipe interface and the oil return pipe interface are communicated with the oil return pipe through an oil guide pipe, the oil inlet pipe interface is communicated with an oil inlet pipeline through an oil guide pipe.
4. The apparatus for determining the shortest spontaneous combustion period of coal according to claim 1, wherein: the temperature sensor comprises an oil bath cavity platinum resistor I, an oil bath cavity platinum resistor II, an oil bath cavity platinum resistor III, an oil bath cavity platinum resistor IV, an oil bath cavity platinum resistor V, a reaction chamber platinum resistor II, a reaction chamber platinum resistor III and a reaction chamber platinum resistor IV, the oil bath cavity platinum resistor I and the oil bath cavity platinum resistor II are respectively arranged at opposite side positions of the middle part of the inner side wall of the oil bath cavity, the oil bath cavity platinum resistor III is arranged at the inner wall of the oil inlet pipe joint, the oil bath cavity platinum resistor IV and the oil bath cavity platinum resistor V are respectively arranged at the inner wall positions of the two oil return pipe joints, the reaction chamber platinum resistor I and the reaction chamber platinum resistor II are respectively arranged at opposite side positions of the middle part of the inner side wall of the reaction chamber, the reaction chamber platinum resistor III is arranged at the middle part of the bottom wall of the reaction chamber, the reaction chamber platinum resistor IV is arranged at the inner wall position of the air outlet pipe joint, and the nine platinum resistors are all electrically connected with the data collector.
5. The apparatus for determining the shortest spontaneous combustion period of coal according to claim 1, wherein: the device is characterized by further comprising a liquid flow meter, stop valves, a pressure reducing valve, a pressure stabilizing valve and a flow controller, wherein the liquid flow meter is assembled in an oil inlet pipeline of the oxidation furnace, the two stop valves are respectively assembled at the external joints of the oil return pipe and the oil outlet pipe, the pressure reducing valve, the pressure stabilizing valve and the flow controller are sequentially assembled on an air guide pipe outside a dry air source, and the stop valves and the flow controller are respectively and electrically connected with a computer.
6. A method for measuring the shortest spontaneous combustion period of coal by using the measuring device comprises the following steps:
step 1, taking a coal bed coal sample;
step 2, preparing and managing a coal sample;
step 3, measuring the ignition temperature of the coal sample;
step 4, checking the equipment state, and loading a coal sample in the checking process;
step 5, starting a gas circuit and an oil circuit of the equipment, and measuring and collecting air temperature, oil temperature and coal temperature data;
and 6, performing operation processing on the recorded data to obtain the shortest natural ignition period result of the coal sample.
7. The method for determining the shortest spontaneous combustion period of coal according to claim 6, wherein: in step 2, the processing flow of the preparation and management of the coal sample is based on the regulation related to GB474, and the following requirements should be met:
1) when the water content of the coal sample is high and the subsequent experiment is influenced, the coal sample is naturally dried, and then all the coal samples are crushed to be less than 10 mm;
2) dividing the coal sample to 300-350 g by a cone stacking quartering method for preparing and analyzing the coal sample, and sealing the rest coal samples according to the original package to serve as the stored and searched coal sample;
3) the pulverized coal sample was stored in a jar under sealed conditions and each measurement was completed within 30 days.
8. The method for determining the shortest spontaneous combustion period of coal according to claim 6, wherein: in step 4, the flow of equipment state inspection and coal sample loading is as follows:
1) checking the air tightness of the air passage, the oil passage and the vacuum cavity of the oxidation furnace, wherein the vacuum degree of the vacuum cavity of the oxidation furnace is not lower than 100 kPa;
2) checking the running states of the temperature sensor, the gas flow controller, the liquid flowmeter and the data acquisition unit, and debugging the existing problems;
3) after the air tightness is confirmed and various related instruments run normally, 100 +/-0.1 g of coal sample to be detected is loaded into the reaction chamber;
4) after the sample is filled, the air tightness of the instrument is checked again.
9. The method for determining the shortest spontaneous combustion period of coal according to claim 6, wherein: in step 5, starting the gas circuit and the oil circuit of the equipment, and measuring and collecting the air temperature, the oil temperature and the coal temperature data as follows:
1) introducing dry air into the reaction chamber at a stable flow of 300mL/min, setting the temperature of the oil bath cavity at 40 ℃, and stabilizing the flow of the heat transfer oil at 10L/min;
2) when the temperature of the coal sample is stable, recording and calculating the temperature of the coal sample at 40 ℃ of the oil bath cavity
Temperature difference between oil inlet and oil return
Temperature difference with air inlet and outlet
3) Setting the temperature of the oil bath cavity to 1.0 ℃/min for temperature programming, starting a data acquisition unit to acquire data such as air flow, air temperature of inlet and outlet air, heat conduction oil flow, oil inlet and return temperature, oil bath temperature, coal sample temperature and the like;
4) when the temperature of the coal sample collected by the data collector exceeds the temperature of the inlet of the oil bath cavity, setting the temperature of the oil bath cavity to be maintained at the current temperature;
5) stopping data acquisition after the temperature of the coal sample is stable, recording and calculating the temperature of the coal sample
Temperature difference between oil inlet and oil return
Temperature difference with air inlet and outlet
10. The method for determining the shortest spontaneous combustion period of coal according to claim 6, wherein: in step 6, the data processing and operation steps are as follows:
calculating step of shortest natural ignition period of coal
1) Calculating the coal chemical reaction rate parameter ka
2) Calculating the shortest spontaneous combustion period tau of the coal, wherein the unit is day (d):
shortest spontaneous combustion period of coal τ:
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