Wood-bamboo dust cloud minimum ignition temperature testing device

Abstract

The utility model provides a device for testing the lowest ignition temperature of wood-bamboo dust cloud, which can form uniform and stable dust cloud, truly simulate the states of flammable dust cloud with different particle sizes under various process conditions, and is convenient to observe and accurate and reliable in test result. The testing device comprises a compressed air inlet pipe, a heat-resistant glass pipeline, a heating furnace, a funnel-shaped dust storage device and an electric control feeding valve, the heating furnace comprises a transparent quartz tube with a horizontal tube section and a vertical tube section which are communicated, and a horizontal tube section heating unit and a vertical tube section heating unit which are used for heating the horizontal tube section and the vertical tube section respectively; the horizontal thermocouple and the vertical thermocouple respectively extend into the horizontal pipe section and the vertical pipe section; the compressed air inlet pipe, the heat-resistant glass pipeline and the horizontal pipe section are communicated in sequence; and a bottom outlet of the funnel-shaped dust storage device is communicated with a dust inlet in the pipe wall of the heat-resistant glass pipeline through an electric control charging valve.

Description

TECHNICAL FIELD

[0001] The utility model relates to the combustible dust cloud combustion and explosion technology research field in the wood -bamboo industrial production and processing process, and specifically is a kind of wood -bamboo quality product production and processing process wood -bamboo quality dust cloud minimum ignition temperature testing device and testing method. BACKGROUND

[0002] Wood -bamboo product production and processing process often accompanied by a large amount of wood powder, bamboo powder and other combustible dust. Combustible dust is concentrated by dust removal facilities. Since the dust removal pipeline conveying process is mostly in dry state, friction and collision heating occurs during conveying, and reaches the ignition point under certain temperature conditions, instantaneously burns and releases a large amount of energy, forms explosion wave and explosion flame and causes pressure to rise sharply, induces dust explosion accident, causes serious personnel injury and economic loss. Therefore, dust explosion prevention has become an important research topic for wood -bamboo processing industry to prevent and control major accidents.

[0003] At present, domestic and foreign research institutes and enterprises about dust cloud combustion and explosion parameter test research are mostly carried out by using industry-related standard requirements. Dust cloud minimum ignition temperature is the main index to evaluate the ignition difficulty of wood -bamboo dust, and is the core parameter to characterize the combustible dust combustion and explosion risk, which can help us understand the ignition mechanism of dust cloud. The testing method and device of dust cloud minimum ignition temperature are mainly based on "Determination of Dust Cloud Minimum Ignition Temperature" (GB / T 16429-1996). The testing device described in the standard is mainly to blow a certain mass of dust from the dust storage into the furnace tube of the heating furnace by compressed air to form a dust cloud, so that the combustible dust is uniformly distributed in the furnace tube, and the dust cloud minimum ignition temperature is determined by controlling the step temperature in the furnace tube to observe whether the flame is formed in the dust cloud in the furnace tube within the specified time.

[0004] However, wood -bamboo materials are of various types, and their physical properties such as density and microstructure differ greatly. In addition, dust is formed under various product processing techniques and different cutting parameters, and the particle size composition and geometric shape of dust particles differ greatly, and dust particles easily affect each other and aggregate, making it difficult to form a dust cloud instantaneously during falling. Moreover, since it is transported into the furnace tube by compressed air from top to bottom, it is easy to form turbulent flow in the furnace tube, resulting in uneven distribution of dust during falling, poor dust cloud effect, and affecting the accuracy of dust minimum ignition temperature determination and the reliability of explosion prevention.

[0005] In addition, combustible dust is usually generated by multiple workstations in actual production, and is transported to the dust collector through the conveying pipeline of the dust suction device for collection and treatment. In this process, the combustible dust is not transported in a single horizontal or vertical direction, nor is it uniformly distributed in space. The concentration and particle size distribution of the dust cloud are basically constant in the test conditions, which not only increases the complexity of the raw material screening process during testing, but also makes the data obtained not reflect the actual situation in the production process, and the research results still cannot prevent the occurrence of dust explosion accidents in actual production.

[0006] Therefore, it is of great significance to develop a combustible dust combustion and explosion performance testing device that can meet the actual process conditions and truly simulate and characterize the minimum ignition temperature of the combustible dust cloud under the actual process conditions. Practical new type content

[0007] The wood-bamboo dust cloud minimum ignition temperature testing device can prevent dust accumulation, form a uniform and stable dust cloud, truly simulate the state of combustible dust clouds of different particle sizes under actual process conditions, has strong adaptability, is easy to observe, can perform real-time characterization of the minimum ignition temperature of the combustible dust cloud, and the test results are more accurate and reliable, thereby providing technical support for revealing the combustion and explosion mechanism of combustible dust and improving the technical level of on-site prevention and control equipment.

[0008] To achieve the above-mentioned purpose, the wood-bamboo dust cloud minimum ignition temperature testing device adopts the following technical solutions:

[0009] A wood-bamboo dust cloud minimum ignition temperature testing device, comprising a compressed air inlet pipe, a heat-resistant glass pipeline, a heating furnace, a funnel-shaped dust storage device, and an electrically controlled feeding valve. The heating furnace comprises a transparent quartz tube with a horizontal tube section and a vertical tube section, a horizontal tube section heating unit and a vertical tube section heating unit for heating the horizontal tube section and the vertical tube section respectively, and a horizontal thermocouple and a vertical thermocouple respectively inserted into the horizontal tube section and the vertical tube section. The compressed air inlet pipe, the heat-resistant glass pipeline, and the horizontal tube section are sequentially connected. The bottom outlet of the funnel-shaped dust storage device is communicated with the dust inlet on the wall of the heat-resistant glass pipeline through the electrically controlled feeding valve.

[0010] As a further improvement of the wood-bamboo dust cloud minimum ignition temperature testing device, an orifice rectifier plate is arranged inside the heat-resistant glass pipeline, so that the compressed air after passing through the rectifier plate forms a uniformly distributed conveying airflow. The rectifier plate is located between the air inlet end of the heat-resistant glass pipeline and the dust inlet.

[0011] As further improvement of the wood bamboo quality dust cloud minimum ignition temperature testing device, the straightening plate includes multiple blocks, the multiple blocks are arranged in the heat-resistant glass pipeline inside the air inlet end and the dust inlet, and the opening rate of each straightening plate increases from the air inlet end to the dust inlet.

[0012] As further improvement of the wood bamboo quality dust cloud minimum ignition temperature testing device, the straightening plate has three blocks, namely the straightening large hole plate, the straightening medium hole plate and the straightening small hole plate with opening rates of 60%, 75% and 90% respectively.

[0013] As further improvement of the wood bamboo quality dust cloud minimum ignition temperature testing device, the horizontal pipe section heating unit and the vertical pipe section heating unit include resistance wires wound on the outer walls of the horizontal pipe section and the vertical pipe section.

[0014] As further improvement of the wood bamboo quality dust cloud minimum ignition temperature testing device, the controller, the horizontal pipe section heating unit, the vertical pipe section heating unit, the horizontal direction thermocouple, the vertical direction thermocouple and the electric control feeding valve are connected with the controller.

[0015] As further improvement of the wood bamboo quality dust cloud minimum ignition temperature testing device, the wind speed meter inserted into the horizontal pipe section for measuring the wind speed in the horizontal pipe section and the differential pressure meter for measuring the pressure difference before and after the straightening plate are included, and the wind speed meter and the differential pressure meter are connected with the controller.

[0016] As further improvement of the wood bamboo quality dust cloud minimum ignition temperature testing device, the data acquisition card and the USB interface connected with the controller are included, the data acquisition card is electrically connected with the wind speed meter, the differential pressure meter, the horizontal direction thermocouple and the vertical direction thermocouple, and is used for collecting wind speed, pressure and temperature data.

[0017] As further improvement of the wood bamboo quality dust cloud minimum ignition temperature testing device, the heat-resistant glass pipeline is a Z-shaped transparent glass pipe.

[0018] As further improvement of the wood bamboo quality dust cloud minimum ignition temperature testing device, the heat-resistant glass pipeline is connected with the horizontal pipe section through a connecting flange.

[0019] The wood bamboo quality dust cloud minimum ignition temperature testing method is simple to operate, can be applied to dusts with different particle sizes, can truly reflect the specific application scene in the actual production process, has good repeatability, and the test result is accurate and reliable.

[0020] The wood bamboo quality dust cloud minimum ignition temperature testing method uses the wood bamboo quality dust cloud minimum ignition temperature testing device, and includes the following steps:

[0021] S1, test device installation and debugging: ensure that each part is connected perfectly and ensure normal operation;

[0022] S2, according to the set test requirements to control the temperature stability;

[0023] S3, according to the concentration requirements to weigh a certain mass of dust sample after particle size screening, and put into the hopper type dust storage for use;

[0024] S4, adjust the conveying gas flow in the heat-resistant glass pipeline to the set pressure;

[0025] S5, open the electric control feeding valve, the dust in the hopper type dust storage is sprayed into the heat-resistant glass pipeline, forms the dust cloud and enters the quartz tube in the heating furnace;

[0026] S6, according to the determination method in GB / T 16429-1996, the ignition conditions of the horizontal pipe section and the vertical pipe section in the quartz tube are observed respectively, the heating temperature is adjusted repeatedly according to whether ignition occurs, the corresponding temperature data are recorded, and the minimum dust cloud ignition temperature is finally determined.

[0027] As a further improvement of the above-mentioned wood bamboo dust cloud minimum ignition temperature test method, the temperature, pressure and wind speed in the horizontal pipe section and the vertical pipe section during the experiment are collected, and the data are transmitted to the U disk or computer through the USB interface for storage.

[0028] As a further improvement of the above-mentioned wood bamboo dust cloud minimum ignition temperature test method, after step S6, there is a step:

[0029] S8, close and clean the test device: the horizontal pipe section heating unit and the vertical pipe section heating unit stop heating, after the quartz tube cools down, the compressed air stops supplying, and the dust or combustion dust residue in the heat-resistant glass pipeline and the quartz tube is cleaned.

[0030] Compared with the prior art, the utility model has the advantages that:

[0031] 1, the pipeline heating part of the test device is provided with horizontal direction and vertical direction, the particle size requirement of the dust is relatively loose, the dust cloud state formed in the horizontal direction and the vertical direction pipeline can truly reflect the specific application scene in the actual production process, the repeated operation is simple, and the test data result is more accurate and reliable.

[0032] The quartz tube has at least a horizontal pipe section and a vertical pipe section, and the compressed air enters from the horizontal pipe section and then enters the vertical pipe section from bottom to top, the dust cloud is stable and uniform in the quartz tube, the dust does not gather, the adaptability to different dust particles is good, the test accuracy is improved, and explosion is avoided.

[0033] The transparent quartz tube is adopted, so that the tester can directly observe the real state of the dust cloud under different conditions, auxiliary devices for indirect observation are omitted, the structure is simplified, and the accuracy and reliability of test data are improved.

[0034] 2、 The heat-resistant glass pipeline of the testing device is provided with rectifier plates, in particular, the rectifier hole plates with different opening rates are arranged at intervals, which can effectively avoid the formation of turbulent flow of compressed air, and is more convenient for the uniform dispersion of dust, the dust cloud effect in the pipeline is good, and the testing precision of the device is improved.

[0035] The heat-resistant glass pipeline adopts a Z-shaped transparent glass tube with two horizontal sections and one vertical section, and the rectifier large hole plate, the rectifier medium hole plate and the rectifier small hole plate with opening rates of 60%, 75% and 90% are arranged in the horizontal section connected with the compressed air inlet pipe for rectification, so that the dust cloud diffusion effect in the heat-resistant glass pipeline and the quartz tube is best, and the dust cloud is uniformly dispersed.

[0036] 3、 The utility model is improved according to the requirements of GB / T 16429-1996, supports remote process control, and greatly improves operability and safety, and can completely provide technical support for revealing combustible dust explosion mechanism, improving on-site prevention and control equipment technology level. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the technical scheme or embodiment of the utility model, the following describes the drawings, and obviously, the drawings in the following description are only one embodiment of the utility model, and other drawings can be obtained according to the drawings for the ordinary skilled in the art without creating creative labor.

[0038] Figure 1 It is a whole schematic view of a wood bamboo quality dust cloud minimum ignition temperature testing device.

[0039] Figure 2 It is Figure 1 It is an enlarged view of the local part A.

[0040] Figure 3 It is a front view of a control box in a control unit of a wood bamboo quality dust cloud minimum ignition temperature testing device.

[0041] Figure 4 It is a back view of a control box in a control unit of a wood bamboo quality dust cloud minimum ignition temperature testing device.

[0042] : 1, compressed air inlet pipe; 2, pressure regulating switch; 3, funnel type dust storage; 4, electric control feeding valve; 5, differential pressure gauge; 6, heat-resistant glass pipeline; 61, rectifier large hole plate; 62, rectifier medium hole plate; 63, rectifier small hole plate; 7, anemometer; 8, connecting flange; 9, heating furnace; 91, Z-shaped quartz tube, 92, horizontal pipe section heating unit; 93, horizontal thermocouple; 94, heating furnace body, 95, vertical thermocouple; 96, vertical pipe section heating unit; 10, purification filter device; 11, control cabinet; 1101, cabinet body; 1102, touch display screen; 1103, total power switch button; 1104, horizontal pipe section heating unit switch button; 1105, vertical pipe section heating unit switch button; 1106, electric control feeding valve switch button; 1107, differential pressure gauge interface; 1108, anemometer interface; 1109, USB interface; 1110, horizontal pipe section heating unit temperature control interface; 1111, vertical pipe section heating unit temperature control interface; 1112, horizontal thermocouple temperature display interface; 1113, vertical thermocouple temperature display interface. DETAILED DESCRIPTION

[0043] The utility model discloses through the content in GB / T 16429-1996 in -depth study, the testing device structure in the standard is improved and optimized, the purpose is real simulation reality process condition combustible dust cloud state, and the real -time representation of the minimum ignition temperature of combustible dust cloud is carried out, and the technical support is provided for the combustible dust explosion mechanism reveals, the scene prevention and control equipment technical level promotion.

[0044] The utility model discloses through the content in GB / T 16429-1996 in -depth study, the testing device structure in the standard is improved and optimized, the purpose is real simulation reality process condition combustible dust cloud state, and the real -time representation of the minimum ignition temperature of combustible dust cloud is carried out, and the technical support is provided for the combustible dust explosion mechanism reveals, the scene prevention and control equipment technical level promotion.

[0045] EMBODIMENT

[0046] Referring to the accompanying drawings, Figure 1 The utility model provides a kind of wood bamboo quality dust cloud minimum ignition temperature testing device, including compressed air inlet pipe 1, pressure regulating switch 2, funnel type dust storage 3, electric control feeding valve 4, differential pressure gauge 5, heat-resistant glass pipeline 6, anemometer 7, connecting flange 8, heating furnace 9, purification filter device 10 and control cabinet 11 etc.

[0047] Referring to the accompanying drawings, Figure 1 , Figure 2 Preferably, the heat-resistant glass pipeline 6 is a Z-shaped transparent glass tube, with a longer end connected to compressed air through the pressure regulating switch 2 and a shorter end connected to the Z-shaped quartz tube 91 in the heating furnace 9. The heat-resistant glass pipeline 6 is internally fitted with a rectifier large hole plate 61, a rectifier medium hole plate 62, and a rectifier small hole plate 63 from the air inlet end. A funnel type dust storage 3 is externally installed on the side of the rectifier small hole plate, and the heat-resistant glass pipeline 6 and the funnel type dust storage 3 are connected through the electric control feeding valve 4.

[0048] Referring to the accompanying drawings Figure 2 Further, the rectifier large-hole plate 61, the rectifier medium-hole plate 62 and the rectifier small-hole plate 63 installed in the heat-resistant glass pipeline 6 have an opening rate of 60%, 75% and 90% respectively, and are arranged in the order of increasing opening rate along the direction of air inlet, so as to make the compressed air form a uniform air flow.

[0049] Referring to the accompanying drawings Figure 1 Preferably, the heating furnace 9 comprises a Z-shaped quartz tube 91, a horizontal tube segment heating unit 92, a horizontal thermocouple 93, a heating furnace body 94, a vertical thermocouple 95, a vertical tube segment heating unit 96 and the like. The Z-shaped quartz tube 91 and the heating furnace body 94 are both made of transparent material. The horizontal end of the Z-shaped quartz tube 91 is connected to the heat-resistant glass pipeline 6 through the connecting flange 8, and the vertical end is connected to the dust or ash purification filter device 10 for collecting dust or ash after spraying.

[0050] Referring to the accompanying drawings Figure 1 , Figure 3 , Figure 4 The control cabinet 11 comprises a cabinet body 1101, a touch display screen 1102, a total power switch 1103, a horizontal tube segment heating unit switch button 1104, a vertical tube segment heating unit switch button 1105, an electrically controlled feeding valve switch button 1106, a differential pressure gauge interface 1107, an anemometer interface 1108, a USB interface 1109, a horizontal tube segment heating unit temperature control interface 1110, a vertical tube segment heating unit temperature control interface 1111, a horizontal thermocouple temperature display interface 1112, a vertical thermocouple temperature display interface 1113, a data acquisition card (not shown in the figure) and the like, all of which are existing mature technologies and can be directly selected from the market. The front side of the control box is provided with the total power switch 1103, the horizontal tube segment heating unit switch button 1104, the vertical tube segment heating unit switch button 1105, the electrically controlled feeding valve switch button 1106 and the like, and the back side of the control box is provided with the differential pressure gauge interface 1107, the anemometer interface 1108, the USB interface 1109, the horizontal tube segment heating unit temperature control interface 1110, the vertical tube segment heating unit temperature control interface 1111, the horizontal thermocouple temperature display interface 1112 and the vertical thermocouple temperature display interface 1113, which are respectively connected to the data acquisition card (not shown in the figure) installed inside the control cabinet 11.

[0051] Referring to the accompanying drawings Figure 1 , Figure 2 The other features, such as the compressed air inlet pipe 1, the pressure regulating switch 2, the funnel-shaped dust storage 3, the electrically controlled feeding valve 4, the differential pressure gauge 5, the anemometer 7, the connecting flange 8, the purification filter device 10 and the like, are all existing mature technologies and can be directly selected from the market or entrusted to process.

[0052] The utility model discloses a kind of wood bamboo quality dust cloud minimum ignition temperature testing methods, which are simple and easy to operate, can be applied to dust of different particle sizes, truly reflect the specific application scenarios in practical production process, and have good repeatability, accurate and reliable test results.

[0053] S1, install and debug the testing device: connect the compressed air, connect each unit in the testing device with the control cabinet 11 using a data cable, turn on the main power supply of the control cabinet 11, and debug each part to ensure that each system is connected properly and can operate normally.

[0054] S2, turn on the device main power switch 1103, start the horizontal pipe section heating unit switch button 1104 and the vertical pipe section heating unit switch button 1105, and control the temperature to be stable according to the set test requirements, and start the data acquisition system to make it in normal working condition.

[0055] S3, weigh a certain amount of dust sample after particle size screening according to the concentration requirement, and place it in the hopper-type dust storage 3 for use.

[0056] S4, turn on the pressure regulating switch 2 to adjust the conveying airflow in the heat-resistant glass pipeline 6 to the set pressure.

[0057] S5, open the electric control feeding valve 4 to spray the dust in the hopper-type dust storage 3 into the conveying pipeline, form a dust cloud, and then enter the Z-shaped quartz tube 91 in the heating furnace 9.

[0058] S6, observe the ignition conditions of the horizontal pipe section and the vertical pipe section in the Z-shaped quartz tube 91 according to the determination method in GB / T 16429-1996, adjust the heating temperature repeatedly according to whether it ignites or not, record the corresponding temperature data, and finally determine the dust cloud minimum ignition temperature.

[0059] S7, data acquisition: through the data acquisition card, the temperature, pressure and wind speed changes in the pipeline during the experiment can be monitored, and the data can be transmitted to the U disk or computer through the USB interface 1109 for storage, so as to further analyze later.

[0060] S8, turn off and clean the testing device: turn off the heating element and the data acquisition system, turn off the compressed air pressure regulating switch 2 and the main power switch button 1103 after the quartz tube 91 cools down, and clean the dust or burning dust residue inside the heat-resistant glass pipeline 6 and the Z-shaped quartz tube 91.

Claims

1. A minimum ignition temperature testing device for wood and bamboo dust clouds, comprising a compressed air inlet pipe, a heat-resistant glass pipe, a heating furnace, a funnel-shaped dust storage device, and an electrically controlled feeding valve, characterized in that: The heating furnace comprises a transparent quartz tube with communicating horizontal and vertical tube sections, horizontal and vertical tube section heating units for heating the horizontal and vertical tube sections respectively, horizontal and vertical thermal couples respectively extending into the horizontal and vertical tube sections, a compressed air inlet pipe, a heat-resistant glass pipe and a horizontal tube section in sequence communication, and a funnel-shaped dust storage device.

2. The wood-bamboo dust cloud minimum ignition temperature test apparatus according to claim 1, characterized in that: A rectifying plate with openings is arranged inside the heat-resistant glass pipe to make the compressed air form a uniform distribution of conveying air flow after passing through the rectifying plate.

3. The wood-bamboo dust cloud minimum ignition temperature test apparatus according to claim 2, characterized in that: The rectifying plate is arranged between the air inlet end of the heat-resistant glass pipe and the dust inlet.

4. The wood-bamboo dust cloud minimum ignition temperature test apparatus according to claim 3, characterized in that: The rectifying plate comprises a plurality of rectifying plates arranged in the heat-resistant glass pipe between the air inlet end and the dust inlet, and the opening rate of each rectifying plate increases from the air inlet end to the dust inlet.

5. The minimum ignition temperature testing device for wood and bamboo dust clouds as described in claim 1, characterized in that: The rectifying plate comprises three rectifying plates with opening rates of 60%, 75% and 90% respectively.

6. The wood-bamboo dust cloud minimum ignition temperature test apparatus according to any one of claims 1-5, characterized in that: The horizontal and vertical tube section heating units comprise resistance wires wound on the outer walls of the horizontal and vertical tube sections.

7. The wood-bamboo dust cloud minimum ignition temperature test apparatus according to claim 6, characterized in that: The controller is connected with the horizontal and vertical tube section heating units, the horizontal and vertical thermal couples and the electrically-controlled feeding valve. The wind speed meter and the pressure difference meter are connected with the controller.

8. The wood-bamboo dust cloud minimum ignition temperature test apparatus according to claim 7, characterized in that: The data acquisition card and the USB interface are connected with the controller, and the data acquisition card is electrically connected with the wind speed meter, the pressure difference meter, the horizontal and vertical thermal couples for collecting wind speed, pressure and temperature data.

9. The wood-bamboo dust cloud minimum ignition temperature test apparatus of claim 1, wherein: the ignition source is a hot wire; and the hot wire is a 1.6 mm diameter nichrome wire. 9 The heat-resistant glass pipe is a Z-shaped transparent glass pipe.

10. The wood-bamboo dust cloud minimum ignition temperature test apparatus of claim 1, wherein: The heat-resistant glass pipe and the horizontal tube section are connected by a connecting flange.

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