A method for establishing a section combustion model of straw pellet fuel and a detection device thereof

Abstract

A method for establishing a section combustion model of straw molded fuel and a detection device thereof, relating to the technical field of establishing a section combustion model of biomass molded fuel. To solve the problem that there are few existing section distribution diagrams of the combustion characteristics of biomass molded fuel beds and the establishment method is unclear. The present application adopts a temperature differential method or a temperature gas phase method, first using a detection device to collect and record the actual parameters of the existing biomass molded fuel bed, and obtain a large number of distribution diagrams of the combustion characteristics, and then according to the temperature differential method or the temperature gas phase method proposed in the present application, the combustion characteristics section distribution diagram of each region is analyzed, thereby achieving the establishment of a section combustion model of straw molded fuel. The present invention is applicable to the technical field of establishing a section combustion model of biomass molded fuel.

Description

Technical Field

[0001] The invention relates to the technical field of establishing a biomass briquette fuel section combustion model, and in particular to an establishing method for a straw briquette fuel section combustion model and a detection device thereof. Background Art

[0002] At present, my country's biomass fuel molding technology is relatively mature, but the type of biomass fuel molding special combustion equipment is single, the combustion effect is poor, and the energy efficiency is low. The main reason is that the research on the combustion mechanism and combustion characteristics of biomass molding fuel is not in-depth enough. Although biomass molding fuel and coal are both solid carbon and hydrogen fuels, the elemental analysis and industrial analysis of the composition are different. The volatile matter of biomass molding fuel is generally above 60%, and the ash content is generally around 10%, which leads to a large difference in the combustion characteristics of biomass and coal.

[0003] my country has abundant straw reserves, and in recent years, direct combustion technology of biomass briquette fuel has been widely used in my country. However, the composition and stacking state of straw briquette fuel are quite different from those of wide-screened coal, and there are differences in the design and operation of straw briquette fuel industrial boilers and wide-screened coal. At present, the combustion process of straw briquette fuel is unclear, and the design and operation of most industrial boilers refer to wide-screened coal furnaces, which makes the boilers have low thermal efficiency, uneven boiler air distribution, high pollutant and particulate matter emissions, and coking of heating surfaces and grates. Summary of the invention

[0004] In order to solve the problems that the existing biomass briquette fuel bed combustion characteristic section distribution diagrams are few and the establishment method is unclear, the present invention proposes a method for establishing a straw briquette fuel section combustion model and a detection device thereof.

[0005] The method for establishing a straw briquette fuel section combustion model of the present invention includes a temperature differential method or a temperature gas phase method;

[0006] The specific steps of the temperature differential method are as follows:

[0007] Step 1: Measure the temperature curve of each position of the bed layer by a straw briquette fuel detection device: Draw the temperature curve of each position of the bed layer according to the temperature data measured by the straw briquette fuel combustion detection device, and differentiate the temperature curve of each position of the bed layer to obtain a heating rate curve;

[0008] Step 2: Mark the time nodes of the preheating and drying stage at each position of the bed layer in the coordinate system to determine the preheating and drying area;

[0009] Step 3: Mark the time nodes of the volatile combustion stage at each position of the bed layer in the coordinate system to determine the combustion zone of the volatile analysis;

[0010] Step 4: Find out the time nodes of the mixed combustion stage at each position of the bed layer and mark them in the coordinate system to determine the mixed combustion zone;

[0011] Step 5: Find out the time nodes of the coke combustion stage at each position of the bed layer and mark them in the coordinate system to determine the coke combustion zone;

[0012] Step 6: Find out the time nodes of the burnout stage at each position of the bed layer and mark them in the coordinate system to determine the burnout zone;

[0013] Step 7: With time as the horizontal axis and the thickness direction of the material layer as the vertical axis, mark the temperature and heating rate nodes at each position of the bed layer on the coordinate axis, and establish a section combustion characteristic model of straw briquette fuel based on each bed layer node dividing the combustion zone;

[0014] Furthermore, in the step 1, the temperature curve and the heating rate curve at each location of the bed layer are analyzed according to the data measured by the detection device to divide the combustion stage of the straw briquette fuel;

[0015] Furthermore, the specific method for determining the preheating and drying zone in the step 2 is as follows: the 0N1 area with a slower heating rate at each position of the bed is defined as the preheating and drying stage of the straw pellet fuel, the time nodes of the preheating and drying stage at each position of the bed are determined and marked in the coordinate system, and the curve N1L1 is obtained by connecting each node, and the area enclosed by the curve is the preheating and drying zone;

[0016] Furthermore, the specific method for determining the volatile analysis combustion zone in the step three is as follows: according to the N2 point where the heating rate curve falls back after the first peak appears, the N1N2 area can be considered as the volatile analysis combustion stage in the combustion process of the straw briquette fuel; the same method is used to find the time nodes of the volatile combustion stage at each position in the bed layer and mark them in the coordinate system, and the curve N2L2 is connected to obtain the area surrounded by N1L1 and N2L2 as the volatile analysis combustion zone; the curve RK is the ignition isotherm of the biomass briquette fuel, and the ignition delay time can be determined according to the Semenov thermal explosion theory to determine the ignition isotherm of the straw briquette fuel;

[0017] Further, the specific method for determining the mixed combustion zone according to step 4 is as follows: the heating rate of the region between N2 and N3 in the coordinate system reaches the second peak value, and the peak rate lasts for a period of time, at which time the coke ignites and burns, and there is still a small amount of volatile matter in the straw molding fuel, so the N2N3 region is the mixed combustion stage, the time nodes of the mixed combustion stage at each position in the bed are found and marked in the coordinate system, and the nodes are connected to obtain the curve N3L2, the area surrounded by N2L2 and N3L2 is the mixed combustion zone, and N2L2 is the coke ignition isotherm;

[0018] Further, the specific method for determining the coke combustion zone in the step 5 is as follows: the coordinate system shows that the coke combustion is relatively stable, and the heating rate will not fluctuate greatly. In the late stage of combustion, due to the influence of the ash shell, the heating rate will fluctuate, but the temperature is still rising, so the N3N4 area can be determined as the coke combustion stage; the time nodes of the coke combustion stage at each position in the bed are found and marked in the coordinate system, and the curve N4L3 is obtained by connecting each node. The area surrounded by N3L2 and N4L3 is the coke combustion zone;

[0019] Furthermore, the specific method for determining the burnout zone in step 6 is as follows: N5 is the highest temperature point, and the temperature starts to decrease from N5 to reach the burnout temperature (600°C) at N6, so the N5N6 area can be determined as the burnout stage; the time nodes of the burnout stage at each position in the bed are found and marked in the coordinate system, and the curve N5L4 is obtained by connecting each node. The area surrounded by N4L3 and N5L4 is the burnout zone;

[0020] Further, the specific method of the temperature gas phase method is as follows:

[0021] Step 1: Using a straw briquette fuel combustion detection device to measure the temperature curve and gas phase component curve at different bed positions;

[0022] Step 2: Find the time node corresponding to the combustion temperature at each position of the bed reaching 100°C and mark it in the coordinate system to determine the preheating and drying area;

[0023] Step 3: Find the time nodes corresponding to the combustion temperature reaching 320°C at different bed layers and mark them in the coordinate system to determine the volatile analysis zone;

[0024] Step 4: Find the time node corresponding to the first concentration inflection point of CO concentration at different beds and mark it in the coordinate system to determine the volatile combustion zone;

[0025] Step 5, find out the time nodes corresponding to the second peak temperature inflection point at the combustion temperature in different bed layers and mark them in the coordinate system to determine the coke combustion zone;

[0026] Step 6: Find out the time nodes corresponding to the sudden increase of O2 concentration at different beds and mark them in the coordinate system, dividing the coke combustion zone into a coke reduction zone and a coke oxidation zone;

[0027] Step 7: Find the time nodes corresponding to the combustion temperature reaching 600°C at different bed layers and mark them in the coordinate system to determine the burnout zone;

[0028] Step 8: With time as the horizontal axis and the thickness direction of the material layer as the vertical axis, mark the temperature and gas phase component nodes on each bed coordinate axis, and establish a straw briquette fuel section combustion characteristic model based on each bed node dividing the combustion zone;

[0029] Further, according to the data measured by the detection device in step 1, the temperature curve and gas phase component curve at each location of the bed are analyzed to divide the straw briquette fuel combustion stage;

[0030] Furthermore, the specific method for determining the preheating and drying zone 1 in the step 2 is as follows: With the horizontal axis as the time scale and the vertical axis as the bed height scale, the time points corresponding to the combustion temperature reaching 100°C at 200mm, 150mm, 100mm and 50mm from the grate are connected as isotherms A1B1 to form Fig. 9 The area shown is the preheat drying zone;

[0031] Furthermore, the specific method for determining the volatile analysis zone 10 in step 3 is as follows: connect the time points corresponding to the combustion temperature reaching 320° C. at different bed layers (200 mm, 150 mm, 100 mm, 50 mm) as the ignition isotherm A2B2 to form the following: Fig.10 The area shown is the volatile analysis zone;

[0032] Furthermore, the specific method for determining the volatile combustion zone 11 in step 4 is as follows: according to the time points corresponding to the first concentration inflection point of the CO concentration at different bed layers, the gas phase component line A3B3 formed by connecting the time points is enclosed as follows: Fig.11 The area shown is the fire zone identified by volatile analysis;

[0033] Furthermore, the specific method for determining the coke combustion zone 6 in step 5 is as follows: connect the time points corresponding to the second peak temperature inflection point at the combustion temperature at different beds to form isotherms A4B4, enclosing Fig.12 The area shown is the coke burning zone;

[0034] Furthermore, the specific method of dividing the coke reduction zone and the coke oxidation zone in step 6 is as follows: the time points corresponding to the sudden increase of O2 concentration at different beds are connected to form A4B5, and the coke combustion zone is divided into the coke reduction zone and the coke oxidation zone;

[0035] Furthermore, the specific method for determining the burnout zone in step 7 is as follows: connect the time points corresponding to the combustion temperature reaching 600° C. at different beds to form an A5B6 burnout isotherm, and the enclosed area is the burnout zone;

[0036] The detection device used in the method for establishing a straw briquette fuel section combustion model of the present invention comprises a high-temperature flue gas sampling gun, a filtering unit, a flue gas component analysis unit and a flue gas data acquisition unit;

[0037] The input end of the filtering unit is connected to the output end of the high-temperature flue gas sampling gun, the output end of the filtering unit is connected to the input end of the flue gas component analysis unit, and the analysis data output end of the flue gas component analysis unit is connected to the analysis data input end of the flue gas data acquisition unit;

[0038] Furthermore, the high-temperature flue gas sampling gun includes a sampling tube, a connecting nut and a water-cooling sleeve; the water-cooling sleeve is a pipe with one end open and the other end closed, a through hole is provided in the middle of the end surface of the closed end of the water-cooling sleeve, and one end of the sampling tube passes through the through hole on the closed end surface of the water-cooling sleeve, a thread is processed on the outer cylindrical surface of the open end of the water-cooling sleeve, and the open end of the water-cooling sleeve is threadedly connected to the connecting nut, and a water inlet is provided on the outer surface of one end of the water-cooling sleeve, and a water outlet is provided on the outer surface of the other end of the water-cooling sleeve;

[0039] Furthermore, the inner diameter of the sampling tube is smaller than the inner diameter of the water-cooling jacket;

[0040] Furthermore, when in use, the flue gas sampling point and the water-cooled sampling gun are connected by nuts, and the sampling tube needs to be inserted into the straw molding fuel combustion detection device; the flue gas collected by the flue gas sampling point and the water-cooled sampling gun passes through the filtration system to remove impurities such as moisture, particulate matter, tar, etc. in the flue gas; the filtered flue gas enters the flue gas component analysis system to analyze the components in the flue gas, and finally the flue gas data acquisition system records the data, and records the data every 10 seconds. Each flue gas sampling point is equidistant, and the number of sampling points and the distance between each sampling point can be determined according to the specific structure of the test bench and the test requirements. Then use the existing temperature data acquisition system, the temperature measurement point is composed of a K-type thermocouple and a temperature transmitter, and the data is recorded every 1 minute. Each thermocouple is equidistant, and the number of thermocouples and the distance between each thermocouple can be determined according to the specific structure of the straw molding fuel combustion detection device and the test requirements.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] The present invention overcomes the shortcomings of the prior art and adopts the temperature differential method or the temperature gas phase method. First, the actual parameters of the existing biomass molded fuel bed are collected and recorded by a detection device, and a large number of combustion characteristic distribution diagrams are obtained. Then, the combustion characteristic segment distribution diagram of each region is analyzed according to the temperature differential method or the temperature gas phase method proposed in this application, thereby realizing the establishment of a straw molded fuel segment combustion model. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1The temperature and heating rate curve of straw briquette fuel

[0044] Figure 2 This is the temperature differential method preheating drying section characteristic diagram

[0045] Figure 3 The temperature differential method is used to analyze the combustion section characteristics.

[0046] Figure 4 This is the temperature differential method mixed combustion section characteristic diagram

[0047] Figure 5 This is the temperature differential method coke combustion section characteristic diagram

[0048] Figure 6 The burnout section characteristic diagram of the temperature differential method

[0049] Figure 7 is the temperature curve of each position of the straw briquette fuel bed

[0050] Figure 8 The gas phase composition curve of straw briquette fuel

[0051] Fig. 9 Temperature gas phase preheating drying section characteristic diagram

[0052] Fig.10 The temperature gas phase volatilization analysis shows the section characteristics diagram

[0053] Fig.11 The characteristic diagram of the ignition section is obtained by temperature vapor phase method volatilization analysis

[0054] Fig.12 Temperature gas phase coke combustion section characteristic diagram

[0055] Fig.13 Temperature gas phase coke oxidation and coke reduction section characteristic diagram

[0056] Fig.14 The temperature gas phase burnout section characteristic diagram

[0057] Fig.15 This is the smoke sampling system diagram of straw pellet fuel

[0058] Fig.16 This is the temperature measurement system diagram of straw molding fuel

[0059] Fig.17 The structure diagram of the high temperature flue gas sampling gun

[0060] Explanation of the reference numerals: preheating and drying zone 1, volatile analysis and combustion zone 2, ignition isotherm 3, coke ignition isotherm 4, mixed combustion zone 5, coke combustion zone 6, burnout zone 7, temperature curve 8, heating rate curve 9, volatile analysis zone 10, volatile combustion zone 11, coke reduction zone 12, coke oxidation zone 13, flue gas sampling point 14, high-temperature flue gas sampling gun 15, filtration system 16, flue gas component analysis system 17, flue gas data acquisition system 18, temperature measuring point 19, temperature data acquisition system 20, sampling tube 21, connecting nut 22, water cooling jacket 23, water inlet 24, water outlet 25. DETAILED DESCRIPTION

[0061] Specific implementation method 1: Combination Figures 1 to 6 The present embodiment is described. The method for establishing a straw briquette fuel section combustion model described in the present embodiment includes a temperature differential method or a temperature gas phase method;

[0062] The specific steps of the temperature differential method are as follows:

[0063] Step 1: Measure the temperature curve 8 at each position of the bed layer by the straw briquette fuel detection device: Draw the temperature curve 8 at each position of the bed layer according to the temperature data measured by the straw briquette fuel combustion detection device, and differentiate the temperature curve 8 at each position of the bed layer to obtain the heating rate curve 9;

[0064] Step 2: Mark the time nodes of the preheating and drying stage at each position of the bed layer in the coordinate system to determine the preheating and drying zone 1;

[0065] Step 3, mark the time nodes of the volatile combustion stage at each position of the bed layer in the coordinate system, and determine the combustion zone 2 by volatile analysis;

[0066] Step 4: Find out the time nodes of the mixed combustion stage at each position of the bed layer and mark them in the coordinate system to determine the mixed combustion zone 5;

[0067] Step 5, find out the time nodes of the coke combustion stage at each position of the bed layer and mark them in the coordinate system to determine the coke combustion zone 6;

[0068] Step 6: Find out the time nodes of the burnout stage at each position of the bed layer and mark them in the coordinate system to determine the burnout zone 7;

[0069] Step 7: With time as the horizontal axis and the thickness of the material layer as the vertical axis, mark the temperature and heating rate nodes at each position of the bed layer on the coordinate axis, and establish a straw briquette fuel section combustion characteristic model based on each bed node that divides the combustion zone.

[0070] Specific implementation method 2: Combination Figure 1To explain this embodiment, this embodiment is a further limitation of the establishment method described in the specific embodiment one. This embodiment describes a method for establishing a straw-shaped fuel segment combustion model. In the step one, the temperature curve 8 and the heating rate curve 9 at various locations of the bed are analyzed according to the data measured by the detection device to divide the combustion stages of the straw-shaped fuel.

[0071] Specific implementation method three: Combination Figure 2 To explain this embodiment, this embodiment is a further limitation of the establishment method described in the specific embodiment one. The method for establishing a straw molded fuel segment combustion model described in this embodiment, the specific method for determining the preheating and drying zone 1 in the step 2 is as follows: the 0N1 area with a slower heating rate at each position of the bed is defined as the preheating and drying stage of the straw molded fuel, the time nodes of the preheating and drying stage at each position of the bed are determined and marked in the coordinate system, and the nodes are connected to obtain the curve N1L1, and the area enclosed by it is the preheating and drying zone 1.

[0072] Specific implementation method four: Combination Figure 3 The present embodiment is described. The present embodiment is a further limitation on the establishment method described in the specific embodiment 1. The present embodiment describes a method for establishing a segment combustion model of a straw molded fuel. The specific method for determining the volatile analysis combustion zone 2 in the step 3 is as follows: According to the N2 point where the heating rate curve 9 falls back after the first peak, the N1N2 region can be considered as the volatile analysis combustion stage in the combustion process of the straw molded fuel; the same method is used to find the time nodes of the volatile combustion stage at each position in the bed and mark them in the coordinate system, and the nodes are connected to obtain the curve N2L2. The area surrounded by N1L1 and N2L2 is the volatile analysis combustion zone 2; the curve RK is the ignition isotherm 3 of the biomass molded fuel, and the ignition delay time can be determined according to the Semenov thermal explosion theory to determine the ignition isotherm 3 of the straw molded fuel.

[0073] Specific implementation method five: Combination Figure 4 The present embodiment is described. The present embodiment is a further limitation on the establishment method described in the specific embodiment one. The present embodiment describes a method for establishing a straw-shaped fuel segment combustion model. The specific method for determining the mixed combustion zone 5 according to step four is as follows: the heating rate of the region between N2 and N3 in the coordinate system reaches a second peak value, and the peak rate lasts for a period of time. At this time, the coke ignites and burns, and there are still a small amount of volatile matter in the straw-shaped fuel. Therefore, the N2N3 region is the mixed combustion stage. The time nodes of the mixed combustion stage at each position in the bed are found and marked in the coordinate system. The nodes are connected to obtain the curve N3L2. The region enclosed by N2L2 and N3L2 is the mixed combustion zone 5, and N2L2 is the coke ignition isotherm 4.

[0074] Specific implementation method six: Combination Figure 5 To explain this embodiment, this embodiment is a further limitation of the establishment method described in the specific embodiment one. The method for establishing a straw-shaped fuel section combustion model described in this embodiment, the specific method for determining the coke combustion zone 6 in the step five is as follows: the coordinate system shows that the coke combustion is relatively stable, and the heating rate will not fluctuate greatly. In the later stage of combustion, due to the influence of the ash shell, the heating rate will fluctuate, but the temperature is still rising. Therefore, the N3N4 area can be determined as the coke combustion stage; the time nodes of the coke combustion stage at each position in the bed are found and marked in the coordinate system, and the nodes are connected to obtain the curve N4L3. The area surrounded by N3L2 and N4L3 is the coke combustion zone 6.

[0075] Specific implementation method seven: Combination Figure 6 To explain this embodiment, this embodiment is a further limitation of the establishment method described in the specific embodiment one. The method for establishing a straw-shaped fuel segment combustion model described in this embodiment, the specific method for determining the burnout zone 7 in step six is ​​as follows: N5 is the highest temperature point, and the temperature begins to drop from N5 to reach the burnout temperature (600°C) at N6, so the N5N6 area can be determined as the burnout stage; the time nodes of the burnout stage at each position in the bed are found and marked in the coordinate system, and the nodes are connected to obtain the curve N5L4, and the area surrounded by N4L3 and N5L4 is the burnout zone 7.

[0076] Specific implementation method eight: Combination Figures 7 to 14 This embodiment is described. This embodiment is a further limitation of the establishment method described in the specific embodiment 1. The establishment method of a straw briquette fuel section combustion model described in this embodiment, the specific method of the temperature gas phase method is as follows:

[0077] Step 1: Using a straw briquette fuel combustion detection device to measure the temperature curve and gas phase component curve at different bed positions;

[0078] Step 2: Find the time node corresponding to the combustion temperature at each position of the bed reaching 100°C and mark it in the coordinate system to determine the preheating and drying zone 1;

[0079] Step 3, find out the time nodes corresponding to the combustion temperature reaching 320°C at different bed layers and mark them in the coordinate system to determine the volatile analysis zone 10;

[0080] Step 4: Find the time node corresponding to the first concentration inflection point of CO concentration at different bed layers and mark it in the coordinate system to determine the volatile combustion zone 11;

[0081] Step 5, find out the time nodes corresponding to the second peak temperature inflection point at the combustion temperature of different bed layers and mark them in the coordinate system to determine the coke combustion zone 6;

[0082] Step 6: Find out the time nodes corresponding to the sudden increase of O2 concentration at different beds and mark them in the coordinate system, and divide the coke combustion zone into a coke reduction zone 12 and a coke oxidation zone 13;

[0083] Step 7, find out the time nodes corresponding to the combustion temperature reaching 600°C at different bed layers and mark them in the coordinate system to determine the burnout zone 7;

[0084] Step 8: With time as the horizontal axis and the thickness of the material layer as the vertical axis, mark the temperature and gas phase component nodes on each bed coordinate axis, and establish a straw briquette fuel section combustion characteristic model based on each bed node that divides the combustion zone.

[0085] Specific implementation method nine: Combination Figure 7 and Figure 8 To explain this embodiment, this embodiment is a further limitation of the establishment method described in Specific Embodiment 8. This embodiment describes a method for establishing a straw-shaped fuel segment combustion model. According to the data obtained by using the detection device in step one to analyze the temperature curve and gas phase component curve at various locations in the bed layer, the straw-shaped fuel combustion stage is divided.

[0086] Specific implementation method ten: Combination Fig. 9 This embodiment is described. This embodiment is a further limitation of the establishment method described in the specific embodiment eight. The method for establishing a straw briquette fuel section combustion model described in this embodiment, the specific method for determining the preheating and drying zone 1 in the step 2 is as follows: the horizontal axis is the time scale, the vertical axis is the bed height scale, and the time points corresponding to the combustion temperature reaching 100°C at 200mm, 150mm, 100mm and 50mm from the grate are connected as isotherms A1B1 to form a Fig. 9 The area shown is the preheat drying zone 1.

[0087] Specific implementation method eleven: Combination Fig.10 This embodiment is described. This embodiment is a further limitation of the establishment method described in the specific embodiment eight. The establishment method of a straw briquette fuel section combustion model described in this embodiment, the specific method of determining the volatile analysis zone 10 in the step three is as follows: connect the time points corresponding to the combustion temperature reaching 320°C at different bed layers (200mm, 150mm, 100mm, 50mm) as the ignition isotherm A2B2, forming a Fig.10 The area shown is the volatile analysis zone 10 .

[0088] Specific implementation method 12: Combination Fig.11 This embodiment is described. This embodiment is a further limitation of the establishment method described in the specific embodiment eight. The method for establishing a straw briquette fuel section combustion model described in this embodiment, the specific method for determining the volatile combustion zone 11 in the step four is as follows: according to the time point corresponding to the first concentration inflection point of the CO concentration at different bed layers, the gas phase component line A3B3 formed by connecting the time points is enclosed as follows Fig.11 The area shown is the volatile analysis fire zone 11.

[0089] Specific implementation method 13: Combination Fig.12 This embodiment is described. This embodiment is a further limitation of the establishment method described in the specific embodiment eight. The method for establishing a straw briquette fuel section combustion model described in this embodiment, the specific method for determining the coke combustion zone 6 in the step five is as follows: connect the time points corresponding to the second peak temperature inflection point at the combustion temperature at different bed layers to form an isotherm A4B4, enclosing Fig.12 The area shown is the coke combustion zone 6 .

[0090] Specific implementation method 14: Combination Fig.13 To explain this embodiment, this embodiment is a further limitation of the establishment method described in specific embodiment eight. The method for establishing a straw molded fuel section combustion model described in this embodiment, the specific method of dividing the coke reduction zone 12 and the coke oxidation zone 13 in step six is ​​as follows: the time points corresponding to the sudden increase of O2 concentration in different bed layers are connected to form A4B5, and the coke combustion zone 4 is divided into the coke reduction zone 12 and the coke oxidation zone 13.

[0091] Specific implementation method 15: Combination Fig.14 To explain this embodiment, this embodiment is a further limitation of the establishment method described in specific embodiment eight. The method for establishing a straw molded fuel segment combustion model described in this embodiment, the specific method for determining the burnout zone 7 in step seven is as follows: connect the time points corresponding to the combustion temperature reaching 600°C at different bed layers to form the A5B6 burnout isotherm, and the enclosed area is the burnout zone 7.

[0092] Specific implementation method 16: Combination Figures 15 to 17 The present embodiment is described. The detection device used in the method for establishing a straw briquette fuel section combustion model described in the present embodiment includes a high-temperature flue gas sampling gun 15, a filtering unit 16, a flue gas component analysis unit 17 and a flue gas data acquisition unit 18;

[0093] The input end of the filtering unit 16 is connected to the output end of the high-temperature flue gas sampling gun 15, the output end of the filtering unit 16 is connected to the input end of the flue gas component analysis unit 17, and the analysis data output end of the flue gas component analysis unit 17 is connected to the analysis data input end of the flue gas data acquisition unit 18;

[0094] In this specific implementation mode, when in use, the flue gas sampling point 14 and the water-cooled sampling gun 15 are connected by nuts, and the sampling tube 21 needs to be inserted into the straw molding fuel combustion detection device; the flue gas collected by the flue gas sampling point 14 and the water-cooled sampling gun 15 passes through the filtering system 16 to remove impurities such as moisture, particulate matter, tar, etc. in the flue gas; the filtered flue gas enters the flue gas component analysis system 17 to analyze the components in the flue gas, and finally the flue gas data acquisition system 18 records the data, and records the data every 10 seconds. Each flue gas sampling point 14 is equidistant, and the number of sampling points and the distance between each sampling point can be determined according to the specific structure of the test bench and the test requirements. Then use the existing temperature data acquisition system 20, the temperature measurement point 19 is composed of a K-type thermocouple and a temperature transmitter, and the data is recorded every 1 minute. Each thermocouple is equidistant, and the number of thermocouples and the distance between each thermocouple can be determined according to the specific structure of the straw molding fuel combustion detection device and the test requirements.

[0095] Specific implementation method 17: Combination Fig.17 The present embodiment is described. The present embodiment is a further limitation on the detection device described in the sixteenth embodiment. The detection device used in the method for establishing a straw-shaped fuel section combustion model described in the present embodiment, the high-temperature flue gas sampling gun 15 comprises a sampling tube 21, a connecting nut 22 and a water-cooling sleeve 23; the water-cooling sleeve 23 is a pipe with one end open and the other end closed, a through hole is provided in the middle of the end surface of the closed end of the water-cooling sleeve 23, and one end of the sampling tube 21 passes through the through hole on the closed end surface of the water-cooling sleeve 23, the outer cylindrical surface of the open end of the water-cooling sleeve 23 is processed with threads, and the open end of the water-cooling sleeve 23 is threadedly connected to the connecting nut 22, and a water inlet 24 is provided on the outer surface of one end of the water-cooling sleeve 23, and a water outlet 25 is provided on the outer surface of the other end of the water-cooling sleeve 23.

[0096] Specific implementation method 18: Combination Fig.17 To explain this embodiment, this embodiment is a further limitation of the detection device described in Specific Embodiment 17. In the detection device used in the method for establishing a straw molded fuel section combustion model described in this embodiment, the inner diameter of the sampling tube 21 is smaller than the inner diameter of the water-cooling sleeve 23.

Claims

1. A method for establishing a straw briquette fuel section combustion model, characterized in that: It includes the temperature differential method or the temperature gas phase method; The specific steps of the temperature differential method are as follows: Step 1: Measure the temperature curve (8) at each position of the bed layer by using a straw briquette fuel detection device: Draw the temperature curve (8) at each position of the bed layer according to the temperature data measured by the straw briquette fuel combustion detection device, and differentiate the temperature curve (8) at each position of the bed layer to obtain a heating rate curve (9); Step 2: Mark the time nodes of the preheating and drying stage at each position of the bed layer in the coordinate system to determine the preheating and drying area (1); Step 3, mark the time nodes of the volatile combustion stage at each position of the bed layer in the coordinate system, and determine the combustion zone (2) by volatile analysis; Step 4: Find the time nodes of the mixed combustion stage at each position of the bed layer and mark them in the coordinate system to determine the mixed combustion zone (5); Step 5, find out the time nodes of the coke combustion stage at each position of the bed layer and mark them in the coordinate system to determine the coke combustion zone (6); Step 6: Find the time nodes of the burnout stage at each position of the bed layer and mark them in the coordinate system to determine the burnout zone (7); Step 7: With time as the horizontal axis and the thickness direction of the material layer as the vertical axis, mark the temperature and heating rate nodes at each position of the bed layer on the coordinate axis, and establish a section combustion characteristic model of straw briquette fuel based on each bed layer node dividing the combustion zone; In step 1 of the temperature differential method, the temperature curve (8) and the heating rate curve (9) at each location of the bed layer are analyzed according to the data measured by the detection device to divide the combustion stage of the straw briquette fuel; The specific method for determining the preheating and drying zone (1) in step 2 of the temperature differential method is as follows: the 0N1 area where the heating rate at each position of the bed is relatively slow is defined as the preheating and drying stage of the straw briquette fuel, the time nodes of the preheating and drying stage at each position of the bed are determined and marked in the coordinate system, and the curve N1L1 is obtained by connecting each node, and the area enclosed by the curve is the preheating and drying zone (1); The specific method for determining the volatile analysis combustion zone (2) in step 3 of the temperature differential method is as follows: according to the N2 point where the heating rate curve (9) falls back after the first peak appears, the N1N2 area at this time can be considered as the volatile analysis combustion stage in the combustion process of the straw briquette fuel; using the same method to find the time nodes of the volatile combustion stage at each position in the bed layer and mark them in the coordinate system, connecting each node to obtain the curve N2L2, and the area surrounded by N1L1 and N2L2 is the volatile analysis combustion zone (2); the curve RK is the ignition isotherm (3) of the biomass briquette fuel, and the ignition delay time can be determined according to the Semenov thermal explosion theory to determine the ignition isotherm (3) of the straw briquette fuel; The specific method for determining the mixed combustion zone (5) according to step 4 in the temperature differential method is as follows: the heating rate of the region between N2 and N3 in the coordinate system reaches the second peak value, and the peak rate lasts for a period of time, at which time the coke ignites and burns, and there is still a small amount of volatile matter in the straw pellet fuel, so the N2N3 region is the mixed combustion stage, the time nodes of the mixed combustion stage at each position in the bed are found and marked in the coordinate system, and the nodes are connected to obtain the curve N3L2, the region surrounded by N2L2 and N3L2 is the mixed combustion zone (5), and N2L2 is the coke ignition isotherm (4); The specific method for determining the coke combustion zone (6) in step 5 of the temperature differential method is as follows: the coordinate system shows that the coke combustion is relatively stable, and the heating rate will not fluctuate greatly. In the late stage of combustion, due to the influence of the ash shell, the heating rate will fluctuate, but the temperature is still rising. Therefore, the N3N4 area can be determined as the coke combustion stage; the time nodes of the coke combustion stage at each position in the bed are found and marked in the coordinate system, and the curve N4L3 is obtained by connecting each node. The area surrounded by N3L2 and N4L3 is the coke combustion zone (6); The specific method for determining the burnout zone (7) in step 6 of the temperature differential method is as follows: N5 is the highest temperature point, and the temperature starts to decrease from N5 to N6, reaching the burnout temperature of 600°C, so the N5N6 area can be determined as the burnout stage; the time nodes of the burnout stage at each position in the bed are found and marked in the coordinate system, and the curves N5L4, N4L3 and N5L4 are connected to obtain the burnout zone (7); The specific method of the temperature gas phase method is as follows: Step 1: Using a straw briquette fuel combustion detection device to measure the temperature curve and gas phase component curve at different bed positions; Step 2: Find the time node corresponding to the combustion temperature at each position of the bed reaching 100°C and mark it in the coordinate system to determine the preheating and drying area (1); Step 3, find out the time nodes corresponding to the combustion temperature reaching 320°C at different bed layers and mark them in the coordinate system to determine the volatile analysis zone (10); Step 4: Find the time node corresponding to the first concentration inflection point of CO concentration at different bed layers and mark it in the coordinate system to determine the volatile combustion zone (11); Step 5, find out the time nodes corresponding to the second peak temperature inflection point at the combustion temperature in different bed layers and mark them in the coordinate system to determine the coke combustion zone (6); Step 6: Find the time nodes corresponding to the sudden increase of O2 concentration in different beds and mark them in the coordinate system, and divide the coke combustion zone into a coke reduction zone (12) and a coke oxidation zone (13); Step 7, find out the time nodes corresponding to the combustion temperature reaching 600°C at different bed layers and mark them in the coordinate system to determine the burnout zone (7); Step 8: With time as the horizontal axis and the thickness of the material layer as the vertical axis, mark the temperature and gas phase component nodes on each bed coordinate axis, and establish a straw briquette fuel section combustion characteristic model based on each bed node that divides the combustion zone.

2. The detection device used in the method for establishing a straw briquette fuel section combustion model according to claim 1 is characterized in that: It includes a high-temperature flue gas sampling gun (15), a filtering unit (16), a flue gas component analysis unit (17) and a flue gas data acquisition unit (18); The input end of the filtering unit (16) is connected to the output end of the high-temperature flue gas sampling gun (15), the output end of the filtering unit (16) is connected to the input end of the flue gas component analysis unit (17), and the analysis data output end of the flue gas component analysis unit (17) is connected to the analysis data input end of the flue gas data acquisition unit (18).

3. The detection device used in the method for establishing a straw briquette fuel section combustion model according to claim 2 is characterized in that: The high-temperature flue gas sampling gun (15) comprises a sampling tube (21), a connecting nut (22) and a water-cooling sleeve (23); The water cooling sleeve (23) is a pipe with one end open and the other end closed. A through hole is provided in the middle of the end surface of the closed end of the water cooling sleeve (23), and one end of the sampling tube (21) passes through the through hole on the closed end surface of the water cooling sleeve (23). The outer cylindrical surface of the open end of the water cooling sleeve (23) is threaded, and the open end of the water cooling sleeve (23) is threadedly connected to the connecting nut (22). A water inlet (24) is provided on the outer surface of one end of the water cooling sleeve (23), and a water outlet (25) is provided on the outer surface of the other end of the water cooling sleeve (23).

Images