Evaluation equipment, processing system, evaluation method, and evaluation program for waste plastics

Abstract

To provide an apparatus for evaluating a waste plastic, a processing system, an evaluation method, and an evaluation program, capable of determining whether or not the waste plastic can be used as a pre-kiln fuel based on properties and shapes of the waste plastic.SOLUTION: An apparatus for evaluating a waste plastic to determine whether or not the waste plastic can be used as a pre-kiln fuel includes: a data acquisition part 330 for acquiring a set of data equivalent to a density of an aggregate of waste plastic pieces to be evaluated, a volume and a surface area of each waste plastic piece included in the aggregate; a determination part 360 for determining, based on the set of data, whether or not the aggregate can be used as a pre-kiln fuel for a cement kiln; and a control part 370 for controlling the feeding of the aggregate to a pre-kiln part of the cement kiln if it is determined that the aggregate can be used as the pre-kiln fuel for the cement kiln.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] This invention relates to an evaluation apparatus, processing system, evaluation method, and evaluation program for waste plastics to determine their suitability as fuel for use in kilns. [Background technology]

[0002] In addition to China's import restrictions, the impact of the Basel Convention amendments has accelerated acceptance restrictions in various countries, and a further increase in the amount of waste plastic to be processed domestically is expected in the future. On the other hand, waste plastic has enough heat to be used as fuel for firing. Therefore, the use of waste plastic is being promoted as an alternative fuel (auxiliary fuel) to pulverized coal, which is the main fuel used for firing cement clinker in cement kilns (see Patent Documents 1-6).

[0003] Traditionally, when using combustible solid waste such as waste plastics as fuel for cement kilns, it has been used in the kiln's tail section or calcination furnace, where it has minimal impact on the quality and manufacturing process of the cement clinker. However, as the amount of combustible waste used in the kiln tail section and calcination furnace is approaching saturation, the use of combustible waste in the main burner located at the front of the kiln is being considered. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2001-191658 [Patent Document 2] Patent No. 5014519 [Patent Document 3] Patent No. 6261518 [Patent Document 4] Patent No. 5655485 [Patent Document 5] Japanese Patent Publication No. 2012-202618 [Patent Document 6] Japanese Patent Publication No. 2000-319049 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, when combustible solid waste such as waste plastics is used as auxiliary fuel in the main burner of a cement kiln, the combustible solid waste ejected from the main burner may land on the cement clinker inside the cement kiln and continue burning on its surface (hereinafter referred to as "landing combustion"). When this landing combustion occurs, the cement clinker around the landing point of the combustible waste undergoes reduction firing, causing changes in the color of the cement clinker, which is undesirable.

[0006] As mentioned above, given the expected increase in the use of waste plastics, there is a possibility of accepting waste plastics that have not been used in factories before as cement fuel. Therefore, from the perspective of flammability, it is preferable to pre-set criteria for determining whether the waste plastics in question can be put into the front of the furnace and the conditions for doing so.

[0007] One indicator for determining whether waste plastic can be introduced into the front of the kiln is its particle size. Generally, waste plastic with large particle sizes is more likely to undergo the aforementioned "landing combustion" rather than complete combustion in the airflow within the cement kiln. Therefore, it is advisable to introduce waste plastic into the front of the kiln only if its particle size is smaller than a standard value.

[0008] However, depending on the properties and shape of the waste plastic, even if the particle size is nearly the same, there may be differences in burning time. Therefore, if the acceptance of waste plastic into the kiln front is determined based on particle size, some waste plastics may undergo on-site combustion, potentially degrading the quality of the cement clinker. From another perspective, excessive crushing or sorting to meet the particle size criteria can lead to increased equipment and operating costs, as well as a decrease in the yield of waste plastic usable as kiln front fuel. Furthermore, for example, the method described in Patent Document 4 defines the range of plastic particles to be blown into the burner based on industrial analysis values, component analysis values, and flammability tests by thermogravimetric analysis of the waste plastic, but these analyses take time, making it impossible to respond immediately to changes in the properties of the waste plastic.

[0009] This invention has been made in view of these circumstances, and aims to provide an evaluation device, processing system, evaluation method, and evaluation program for waste plastics that can determine whether or not they can be used as fuel in front of a kiln, taking into account the properties and shape of the waste plastics. [Means for solving the problem]

[0010] (1) In order to achieve the above objective, the waste plastic evaluation device of the present invention is a waste plastic evaluation device for determining whether it can be used as pre-fuel for a cement kiln, and is characterized by comprising: a data acquisition unit that acquires a set of data equivalent to the density of an aggregate of waste plastic pieces to be evaluated, the volume of each individual waste plastic piece contained in the aggregate, and the surface area; a determination unit that determines whether the aggregate can be used as pre-fuel for a cement kiln based on the set of data; and a control unit that controls sending the aggregate to the front of the cement kiln if it is determined that the aggregate can be used as pre-fuel for a cement kiln.

[0011] This allows for the determination of whether waste plastics can be used as fuel in the kiln, taking into account their properties and shape. In other words, it becomes possible to make judgments based on the burning time of not only spherical particles but also plate-shaped particles and low-density polystyrene foam particles. As a result, it is possible to increase the amount of waste plastic that can be converted into fuel without causing ground combustion.

[0012] (2) Furthermore, the waste plastic evaluation apparatus described in (1) above is characterized in that the determination unit determines whether or not the aggregate can be used as pre-fuel for a cement kiln using an index based on the numerical value An = ρ·Vn / Sn, where the density of the aggregate is ρ, the volume of each individual waste plastic piece contained in the aggregate is Vn, and the surface area is Sn. This makes it possible to determine the length of the burning time according to the index, regardless of the shape or material of the waste plastic pieces. The index may be a burning time equivalent to the numerical value An or a burning time using the burning time of fine particles.

[0013] (3) Furthermore, the waste plastic evaluation apparatus described in (2) above is characterized in that the determination unit determines that the aggregate can be used as pre-fuel for a cement kiln when a predetermined proportion or more of waste plastic fragments with a numerical value An of 1 or less than the first threshold are included. In this way, the composition ratio of easily combustible waste plastic fragments is also taken into consideration, and it is possible to flexibly determine whether or not it can be used as pre-fuel for a cement kiln while tolerating the presence of particles that do not meet the standards.

[0014] (4) Furthermore, in the waste plastic evaluation apparatus described in (2) above, the determination unit determines that the aggregate can be used as pre-fuel for a cement kiln if the numerical value An obtained from the representative value of the aggregate or the representative value of the numerical value An is less than or equal to the second threshold. In this way, the numerical value An can be easily calculated by using the representative value of each parameter of a set of data, and it is possible to determine whether or not it can be used as pre-fuel for a cement kiln. The representative value includes the mean and the median.

[0015] (5) Furthermore, the waste plastic evaluation apparatus described in any of (1) to (4) above is further equipped with an image processing unit that calculates the volume and surface area of ​​each waste plastic piece constituting the aggregate based on the image data of the aggregate, and the data acquisition unit is characterized in that it acquires the set of data based on the volume and surface area of ​​each waste plastic piece. In this way, the necessary parameters are calculated by image processing, making it possible to evaluate each waste plastic piece according to its shape.

[0016] (6) Furthermore, the waste plastic processing system of the present invention is characterized by comprising processing equipment that includes a weight measuring unit for measuring the weight of a portion sampled from the aggregate, an image data acquisition unit for acquiring image data of a portion of the aggregate, and a switching unit for switching the destination of the aggregate to the front of the kiln, and a waste plastic evaluation device as described in any of (1) to (5) above. This makes it possible to take data from the supplied waste plastic pieces and transport the waste plastic pieces according to the determination of whether or not they can be used as fuel in front of the cement kiln.

[0017] (7) Furthermore, the present invention provides a method for evaluating waste plastics to determine whether they can be used as pre-fuel for a cement kiln, and is characterized by comprising the steps of: acquiring a set of data equivalent to the density of an aggregate of waste plastic pieces to be evaluated, the volume of each individual waste plastic piece contained in the aggregate, and the surface area; determining whether the aggregate can be used as pre-fuel for a cement kiln based on the set of data; and, if it is determined that the aggregate can be used as pre-fuel for a cement kiln, controlling the assembly to be sent to the front of the cement kiln. This makes it possible to determine whether the waste plastics can be used as pre-fuel for a cement kiln, taking into account the properties and shape of the waste plastics.

[0018] (8) Further, the waste plastic evaluation program of the present invention is an evaluation program for the usability of waste plastic as pre-kiln fuel, which includes a process of acquiring a set of data equivalent to the density of an aggregate of waste plastic pieces to be evaluated, the volume and surface area of each of the waste plastic pieces included in the aggregate, a process of determining whether the aggregate can be used as pre-kiln fuel for a cement kiln based on the set of data, and a process of performing control to send out the aggregate to the pre-kiln part of the cement kiln when it is determined that the aggregate can be used as pre-kiln fuel for the cement kiln, and is characterized by causing a computer to execute these processes. Thereby, it is possible to determine the usability as pre-kiln fuel taking into account the properties and shape of the waste plastic.

Effect of the Invention

[0019] According to the present invention, it is possible to determine the usability as pre-kiln fuel taking into account the properties and shape of the waste plastic.

Brief Description of the Drawings

[0020] [Figure 1] It is a schematic diagram showing a waste plastic treatment system. [Figure 2] It is an example of a block diagram showing waste plastic treatment equipment. [Figure 3] It is a block diagram showing a waste plastic evaluation device. [Figure 4] It is a flowchart showing the operation of a waste plastic evaluation device. [Figure 5] (a) and (b) are respectively a schematic diagram showing image processing and a table showing image processing results. [Figure 6] It is a side cross-sectional view showing a combustion test device for plastic pieces. [Figure 7] It is a graph showing combustion test results. [Figure 8] It is a graph showing the relationship between the numerical value An of plastic pieces and the combustion time. [Figure 9] It is a graph showing the distribution of the particle size and numerical value An of each sample. [Figure 10]This is a flowchart of the experiment leading up to the calculation of the estimated burn time. [Figure 11] This is a schematic diagram showing a combustion test apparatus for fine particles. [Figure 12] This graph shows the estimated burning time for each sample. [Modes for carrying out the invention]

[0021] Embodiments of the present invention will be described below with reference to the drawings.

[0022] [Waste plastic processing system] Figure 1 is a schematic diagram showing a waste plastic processing system 100. The waste plastic processing system 100 comprises a waste plastic processing facility 200 and an evaluation device 300. The processing facility 200 is installed within a cement manufacturing plant 400. The processing facility 200 and the evaluation device 300 are connected by wired or wireless means and transmit and receive information from each other.

[0023] The processing equipment 200 sorts and crushes miscellaneous waste plastics, separates a portion of the processed material, measures its weight, volume (Vn), and surface area (Sn). The evaluation device 300 then determines the density (ρ) from the measured weight and volume, and based on the resulting value An (=ρ × Vn / Sn), performs additional sorting as needed. The evaluation device 300 controls the processing equipment 200 to feed the material into the kiln only if it meets the criteria of value A. This allows data to be collected from the supplied waste plastic pieces, and the waste plastic pieces can be transported according to a determination of whether or not they are usable as fuel in front of the cement kiln.

[0024] [Waste plastic processing facilities] Figure 2 is an example of a block diagram showing a waste plastic processing facility 200. The processing facility 200 includes a coarse crusher 201, a mechanical sorter 202, a secondary crusher 211, measuring units 215 and 225, an air sorter 221, and switching units 218 and 228. Measuring unit 215 includes a weight measuring unit 216 and an image data acquisition unit 217, and measuring unit 225 includes a weight measuring unit 226 and an image data acquisition unit 227. Combustible waste (waste plastic) is first fed into the coarse crusher 201.

[0025] The coarse crusher 201 roughly crushes the input waste plastic into fragments of 100 to 500 mm in size by rotating, for example, a metal cutter with high strength, onto the input waste plastic. The mechanical sorter 202 is a sorter that uses a vibrating screen or air power, and sorts the coarsely crushed waste plastic fragments into light, fine, and heavy materials by mechanical sorting using, for example, the inclination angle, rotation speed, airflow adjustment, number of elements, and screen holes. Preferably, the mechanical sorter 202 is adjusted (inclination, airflow, etc.) by a computer such as the evaluation device 300.

[0026] The secondary crusher 211 is placed in the transport path for the waste plastic pieces that have been sorted as lightweight materials, and further crushes the waste plastic pieces into pieces of 30-50 mm size. The crushed waste plastic pieces are managed in aggregates, and a portion of each aggregate is separated and sent to the measuring unit 215. The measuring unit 215 measures the weight and shape data of the separated portion of waste plastic pieces. This measurement is preferably performed automatically.

[0027] The weight measuring unit 216 measures the total weight of a portion of the waste plastic pieces separated from the aggregate. The image data acquisition unit 217 photographs the portion of the waste plastic pieces separated from the aggregate with a camera and acquires image data. The measurement unit 215 transmits the measurement data to the evaluation device 300.

[0028] The switching unit 218 switches the destination for each aggregate of waste plastic fragments according to the evaluation result of the measurement data from the measurement unit 215. When an aggregate of waste plastic fragments is determined to be usable as fuel in front of the cement kiln, the aggregate is sent to the front of the kiln; when it is not determined to be usable as fuel in front of the kiln, the aggregate is sent to the transport route for fine-grained materials.

[0029] The air separator 221 is placed in the transport path for waste plastic fragments separated as fine particles, and separates the fine particles into light and heavy particles using a constant airflow. The fine particles separated as light particles remain in the transport path for the fine particles as air-separated light particles. The waste plastic fragments that are air-separated light particles are managed in aggregates, and a portion of each aggregate is separated and sent to the measuring unit 225. Preferably, the airflow and other parameters of the air separator 221 are adjusted by a computer such as an evaluation device 300.

[0030] The measuring unit 225 measures the weight and shape data of some of the separated waste plastic pieces. This measurement is preferably performed automatically. Meanwhile, the fine granules that have been sorted as heavy materials are sent to the heavy material transport route.

[0031] The weight measurement unit 226 measures the total weight of a portion of the waste plastic pieces separated from the aggregate of air-selected lightweight materials. The image data acquisition unit 227 photographs the portion of the waste plastic pieces separated from the aggregate of air-selected lightweight materials with a camera and saves it as image data. The measurement unit 225 transmits the measurement data to the evaluation device 300.

[0032] The switching unit 228 switches the destination for each aggregate of waste plastic fragments according to the evaluation result of the measurement data from the measurement unit 225. When an aggregate of waste plastic fragments is determined to be usable as fuel in front of the cement kiln, the aggregate is sent to the front of the kiln; when it is not determined to be usable as fuel in front of the kiln, the aggregate is sent to the heavy transport route.

[0033] The aggregate of waste plastic fragments sorted as heavy material by the mechanical sorting machine 202 is transported through the heavy material transport route and sent directly to the kiln end. Alternatively, the waste plastic fragments sent to the kiln end may undergo additional processing, such as gasification, before being sent to the kiln front or end.

[0034] [Evaluation device for waste plastics] Figure 3 is a block diagram showing the waste plastic evaluation device 300. The waste plastic evaluation device 300 acquires data for each aggregate of waste plastic from the processing facility 200 and evaluates whether the aggregate of waste plastic can be used as pre-fuel fuel.

[0035] The evaluation device 300 is a computer, such as a PC, and consists of a processor that performs processing and memory or a hard disk that stores programs and data. The evaluation device 300 may also be a server device located on the cloud. Furthermore, from the standpoint of reducing processing load, the function of processing measurement data and the function of controlling the operation of the processing equipment 200 may be separated, with control performed on a PC installed on-site and data processing performed on the server device. The evaluation device 300 may also accept input such as judgment conditions from an input device 380 such as a keyboard or mouse, and display the judgment results on an output device 390 such as a display.

[0036] As shown in Figure 3, the evaluation device 300 comprises a transmitting / receiving unit 310, an image processing unit 320, a data acquisition unit 330, a numerical calculation unit 340, an index calculation unit 350, a determination unit 360, and a control unit 370, and the functions of each unit are realized by executing a program.

[0037] The transmitting / receiving unit 310 receives measurement data and image data from the processing equipment 200. It also transmits control information based on the judgment result to the processing equipment 200. The image processing unit 320 calculates the volume and surface area of ​​each waste plastic piece constituting the aggregate based on the image data of the aggregate. The image processing unit can also perform automatic measurements inline. Because the necessary parameters are calculated through image processing in this way, it becomes possible to evaluate each waste plastic piece according to its shape.

[0038] The data acquisition unit 330 acquires a set of data equivalent to the density, volume, and surface area of ​​the aggregate of waste plastic fragments to be evaluated. "Equivalent" means a set of data from which the same result can be obtained, for example, a set of data for "weight, volume, and surface area."

[0039] The numerical calculation unit 340 calculates a numerical value An = ρ·Vn / Sn, where ρ is the density of the aggregate, Vn is the volume of each individual particle contained in the aggregate, and Sn is the surface area. The index calculation unit 350 calculates an index based on the numerical value An = ρ·Vn / Sn of the aggregate. For example, the estimated burning time of the waste plastic fragments constituting the aggregate can be calculated from the numerical value An and the measured burning time of the fine particles. The numerical value An itself may also be used as the index. In that case, the numerical value An obtained from representative values ​​or representative values ​​of the numerical value An can also be used. Representative values ​​include the mean and median.

[0040] The determination unit 360 uses an index based on the numerical value An to determine whether the aggregate can be used as pre-fuel for a cement kiln. This allows for the determination of the burning time according to the index, regardless of the shape or material of the waste plastic fragments. In other words, it becomes possible to determine the burning time not only for spherical particles but also for plate-shaped particles and low-density polystyrene foam particles.

[0041] For example, if a certain proportion or more of waste plastic fragments with a numerical value An below the first threshold are included, the aggregate can be determined to be usable as pre-fuel for a cement kiln. The first threshold is 0.5 × 10⁻⁶. -3 [g / mm 2 ], with 80% being a predetermined proportion. By considering the composition ratio of easily combustible waste plastic fragments in this way, it is possible to flexibly determine whether or not it can be used as pre-fuel fuel while tolerating the presence of non-standard particles.

[0042] Furthermore, if the numerical value An obtained from the representative value of the aggregate, or the representative value of numerical value An, is less than or equal to the second threshold, the aggregate may be determined to be usable as pre-fuel for a cement kiln. For example, the second threshold may be 1.0 × 10⁻⁶.-3 [g / mm 2 ] are examples. In this way, by using the average value of each parameter in a set of data, the numerical value An can be easily calculated, and it is possible to determine whether or not it can be used as fuel in front of the kiln.

[0043] The determination unit 360 may have AI functions, such as a machine learning model. For example, a machine learning model consisting of a neural network with an input layer, a hidden layer, and an output layer can be used. When the density of a waste plastic fragment aggregate, a set of data equivalent to the volume and surface area of ​​individual particles contained in the aggregate, and whether or not to send it to the kiln are known, these are associated and used as training data to train the machine learning model. That is, a set of data equivalent to the density of a waste plastic fragment aggregate, the volume and surface area of ​​individual particles contained in the aggregate are input, and the weights of each neuron in the hidden layer are tuned by repeatedly training the model so that it outputs the correct determination result regarding whether or not to send it to the kiln with a high probability in the output layer. In this case, a convolutional neural network may be used to roughly recognize the target. This makes it possible to evaluate whether or not the aggregate can be used as fuel in front of the cement kiln using accumulated data as training data, without using an index.

[0044] If the control unit 370 determines that the aggregate can be used as pre-fuel for the cement kiln, it controls the sending of the aggregate to the front of the cement kiln. This allows the waste plastic to be used as pre-fuel, taking into account its properties and shape. As a result, the amount of waste plastic that can be converted into fuel can be increased without causing ground combustion.

[0045] [Methods for evaluating waste plastics] (General operation of the evaluation device) Figure 4 is a flowchart showing the operation of the waste plastic evaluation device 300. As shown in Figure 4, first, measurement data is received from the processing equipment 200 (step S1). The measurement data includes weight data and image data.

[0046] Next, the received image data is processed (step S2). This allows for the estimation of the volume and surface area of ​​each sampled waste plastic piece. Details of the volume and surface area estimation will be described later.

[0047] The obtained measurement data and image processing data are acquired as data for calculating the numerical value An (Step S3). Based on the acquired data, the numerical value An = ρ·Vn / Sn is calculated (Step S4). Then, the index is calculated using the numerical value An (Step S5). The index may be the numerical value An itself.

[0048] Next, it is determined whether the aggregate of waste plastic fragments can be used as pre-fuel for the cement kiln (step S6). From an efficiency standpoint, the determination is made based on a set of data, and it is preferable to use an index based on the numerical value An.

[0049] If it is determined that the waste plastic fragments can be used as fuel in front of the kiln, the switching units 218 and 228 of the processing equipment 200 are controlled to send the aggregate of waste plastic fragments to the front of the kiln. On the other hand, if it is determined that the waste plastic fragments cannot be used as fuel in front of the kiln, the switching units 218 and 228 of the processing equipment 200 are controlled to send the aggregate of waste plastic fragments to a location other than the front of the kiln.

[0050] (Image processing) Figures 5(a) and 5(b) are schematic diagrams illustrating the image processing and tables showing the image processing results, respectively. As shown in Figure 5(a), a portion separated from the aggregate of waste plastic fragments is photographed from vertically above, and the image data is received by the evaluation device 300.

[0051] By applying image processing to this image data, each piece of waste plastic is recognized, and the surface area and volume of each piece of waste plastic are calculated. For example, if the total number of separated pieces of waste plastic is N, the area of ​​the main surface Qn, the perimeter Pn, and the thickness tn of the nth flat piece of waste plastic can be estimated by image recognition. If the total weight of the N separated pieces of waste plastic is represented by G, the surface area Sn, volume Vn, and average density of the separated pieces of waste plastic can be obtained from the nth flat piece of waste plastic using the following equation (1).

[0052]

number

[0053] (Calculation of indicators) For example, the numerical value An = ρ·Vn / Sn can be calculated using the average density, surface area, and volume mentioned above as ρ, Sn, and Vn. Alternatively, the estimated burning time Tp = Tf·Anp / Anf of the waste plastic fragments can be used as an indicator for each material. Here, Tf represents the burning time of the fine particles, Anf represents the numerical value An of the fine particles, and Anp represents the numerical value An of the waste plastic fragments.

[0054] [Experiment 1] To investigate the influence of plastic particle size and shape on combustion behavior, combustion tests were conducted using single resin samples in two shapes: plate-shaped and spherical. Industrial analysis was performed on the single resin samples used in the tests, and quantitative values ​​of combustible components (volatile matter and fixed carbon) were used in the analysis of the combustion test results. Table 1 below shows the analysis items and methods. Table 2 shows the results of the industrial analysis of the single resin samples.

[0055] [Table 1]

[0056] [Table 2]

[0057] In the combustion test, an electrically heated batch-type vertical tubular furnace was used to simulate the rapid temperature rise during combustion. Figure 6 is a side cross-sectional view showing the combustion test apparatus for plastic pieces. The apparatus shown in Figure 6 is an isothermal thermogravimetric apparatus and is equipped with the vertical tubular furnace used in the combustion test. The apparatus consists of a heating section, a reaction tube, and a measurement section. The heating section and reaction tube are integrated and can move vertically up and down.

[0058] The measurement unit consists of a PC and an electronic balance. The electronic balance has a hook on its bottom so that the object to be measured can be suspended for weighing, and the sample, placed in a platinum basket, is suspended from this hook. The furnace temperature is measured by a thermocouple and controlled according to a program. The atmospheric gas supplied to the reaction tube flows in through a gas supply port located in the water-cooling jacket at the bottom of the reaction tube, and the flow rate is controlled by a mass flow controller. In addition, nitrogen, an inert gas, is supplied to the electronic balance as a sealing gas to protect it from combustion exhaust gases.

[0059] The sample was placed in a platinum cage and suspended from an electronic balance. The electric furnace, which had been preheated to the predetermined experimental temperature, was quickly raised to the position of the platinum cage, and the combustion test was started. This time was defined as the reaction start time (0 seconds), and the weight loss of the sample during the experiment was continuously measured using the electronic balance. The test was conducted under conditions simulating the furnace environment, at 1400°C and with an O2=21% atmosphere (air conditions).

[0060] The percentage of combustible material remaining in the sample at a given time, X[%] (hereinafter referred to as "remaining combustible material"), was defined by the following equation (2).

number

[0061] Here, in the above equation, m0 is the initial mass, m f m is the mass at the end of the reaction. t The θ represents the mass at time t, and the denominator represents the combustible content. Note that m f This is the weight at which the combustible components in the sample have completely combusted and the measurement on the electronic balance has become constant.

[0062] Figure 7 is a graph showing the results of the combustion test. The combustion behavior of waste plastics can be broadly divided into two stages: the release and combustion of volatile components due to thermal decomposition (hereinafter referred to as volatile component combustion) and char combustion, which results from the combustion of fixed carbon remaining after thermal decomposition. Since the sample used in the test consisted almost entirely of volatile components, only volatile component combustion was evaluated in this test. The volatile component combustion time was defined as the time determined by the following procedure.

[0063] (1) Draw an approximate straight line using plots where the remaining combustible material is in the range of 70-90%. (2) Calculate the proportion of volatile matter in the combustible material from the industrial analysis values. (3) Determine the elapsed time at which the approximate straight line reaches a weight reduction corresponding to the amount of volatile matter.

[0064] Strictly speaking, in this test method, volatile matter combustion and char combustion are thought to proceed almost simultaneously. However, since the rapid weight loss that occurs in the initial stages of a combustion reaction is generally primarily due to volatile matter combustion, the volatile matter combustion time was evaluated using the method described above.

[0065] In this way, the burning time of each sample was evaluated. Figure 8 is a graph showing the relationship between the numerical value An of the plastic piece and the burning time. As shown in Figure 8, we were able to demonstrate that there is a proportional relationship between the numerical value An and the burning time. Table 3 shows the numerical values ​​of An and the volatile content combustion time for each sample. [Table 3]

[0066] [Experiment 2] As shown in Table 2, we attempted to estimate the burning time of samples made by mixing plastic particles with different particle sizes and numerical values ​​(An) in different formulations. The characteristics of each sample are as follows, and the specific formulations are shown in Table 4. Figure 9 is a graph showing the distribution of particle size and numerical value (An) of the particles contained in each sample.

[0067] Sample A: Both particle size and numerical value An are distributed in a relatively small region. Sample B: The particle size is distributed in a relatively large range, but the numerical value An is distributed in a relatively small range. Sample C: The particle size is distributed in a relatively small range, but the numerical value An is distributed in a relatively large range. Sample D: The particle size and numerical value An are distributed within an intermediate range within the sample. Sample E: Both particle size and numerical value An are distributed in a relatively large region.

[0068] [Table 4]

[0069] Figure 10 shows the flowchart of the experiment to calculate the estimated burning time. It is difficult to conduct burning tests that simulate a kiln-like environment with typical laboratory-level testing equipment. Therefore, the burning time of the waste plastic in its original form was estimated by preparing the waste plastic in its original form (Step T1), crushing it (Step T2), measuring the burning time of the fine particles (Step T3), and applying a correction that takes into account the actual size and shape of the waste plastic (Step T4) (Step T5).

[0070] Figure 11 is a schematic diagram showing a combustion test apparatus for fine particles. First, using the test apparatus shown in Figure 11, fine particles of waste plastic were transported by airflow into a furnace simulating a kiln combustion environment, and the combustion time T1 of the fine particles was measured by taking photographs with a high-speed camera.

[0071] Although it is difficult to directly measure the burning time of large-particle waste plastics with the above test apparatus, it has been confirmed that the burning time of plastic particles is roughly proportional to the numerical value An, as shown in Figure 8. Based on this relationship, the burning time Tp of intact waste plastic particles was calculated using the following equation (3) with the burning time Tf of the fine particles and the respective numerical values ​​An, Anp and Anf.

[0072]

number

[0073] In its natural state, waste plastic is a mixture of various particles with different shapes and sizes. However, by analyzing the numerical value An of a large number of particles using image processing, for example, as described below, highly representative data can be extracted.

[0074] A portion of the waste plastic fragments is separated from the aggregate and photographed from vertically above. By processing the image data, each waste plastic fragment is recognized, and the area Qn of the main surface and the perimeter Pn of each waste plastic fragment can be estimated through image recognition. By considering the thickness tn of each individual waste plastic particle, the surface area Sn and volume Vn of a flat waste plastic fragment can be calculated. Furthermore, if the total number of separated waste plastic fragments is N, and the total weight of the N particles is represented by G, the average density of the waste plastic fragments can be obtained using equation (1), and the numerical value An = ρ·Vn / Sn can be calculated.

[0075] Using the method described above, the particles of waste plastic were analyzed to determine the index Ap. Next, the combustion time of the waste plastic particles was estimated for each particle using the procedure shown below. First, as shown in the table below, the combustion time of the fine particles of waste plastic was measured using the test apparatus shown in Figure 11.

[0076] [Table 5]

[0077] Then, based on the burning time of the fine particles, we performed a size correction and calculated the estimated burning time of the actual waste plastic particles as shown in the table below. [Table 6]

[0078] Figure 12 is a graph showing the estimated combustion time of each sample. Figure 12 shows the distribution (median and interquartile range) of the estimated combustion time of the particles contained in the test sample. When compared with the combustion time set as a reference, C and E, which contain many particles with a large numerical value An = ρ × Vn / Sn (0.51 × 10 -3 or more), have a long combustion time and are considered to have a high possibility of falling onto the firing surface. For sample D, in which particles with ρ × Vn / Sn > 0.50 × 10 -3 are generally 20% or less, it was within the reference value.

Explanation of symbols

[0079] 100 Processing system 200 Processing equipment 201 Coarse crusher 202 Mechanical separator 211 Secondary crusher 215, 225 Measuring unit 216, 226 Weight measuring unit 217 Image data acquisition unit 218, 228 Switching unit 221 Pneumatic separator 227 Image data acquisition unit 300 Evaluation device 310 Transceiver 320 Image processing unit 330 Data acquisition unit 340 Numerical calculation unit 350 Index calculation unit 360 Judgment unit 370 Control unit 380 Input device 390 Output device 400 Cement manufacturing plant

Claims

1. An evaluation device for waste plastics to determine whether they can be used as fuel in front of a kiln, A data acquisition unit that acquires a set of data equivalent to the density of an aggregate of waste plastic fragments to be evaluated, the volume of each individual waste plastic fragment contained in the aggregate, and the surface area of ​​each fragment, A determination unit that determines whether the assembly can be used as pre-fuel for a cement kiln based on the aforementioned set of data, The system includes a control unit that controls the sending of the assembly to the front of the cement kiln when it is determined that the assembly can be used as fuel in front of the cement kiln, The determination unit determines whether the aggregate can be used as pre-fuel for a cement kiln, using an index based on the numerical value An = ρ・Vn / Sn, where ρ is the density of the aggregate, Vn is the volume of each individual waste plastic piece contained in the aggregate, and Sn is the surface area. The waste plastic evaluation device is characterized in that the determination unit determines that the aggregate can be used as pre-fuel for a cement kiln when the numerical value An is less than or equal to a first threshold and a predetermined proportion or more of the waste plastic fragments are included.

2. The waste plastic evaluation apparatus according to claim 1, characterized in that the determination unit determines that the aggregate can be used as pre-fuel for a cement kiln when the numerical value An obtained from the representative value of the aggregate or the representative value of the numerical value An is less than or equal to a second threshold.

3. The system further includes an image processing unit that calculates the volume and surface area of ​​each waste plastic piece constituting the aggregate based on the image data of the aggregate. The waste plastic evaluation apparatus according to claim 1 or 2, characterized in that the data acquisition unit acquires the set of data based on the volume and surface area of ​​each waste plastic piece.

4. An evaluation device for waste plastics to determine their suitability as fuel for use in kilns, Processing equipment and A waste plastic processing system comprising: The evaluation device is A data acquisition unit that acquires a set of data equivalent to the density of an aggregate of waste plastic fragments to be evaluated, the volume of each individual waste plastic fragment contained in the aggregate, and the surface area of ​​each fragment, A determination unit that determines whether the assembly can be used as pre-fuel for a cement kiln based on the aforementioned set of data, If it is determined that the assembly can be used as fuel in front of the cement kiln, the control unit controls the sending of the assembly to the front of the cement kiln, Equipped with, The aforementioned processing equipment is A weight measuring unit for measuring the weight of a portion sampled from the aforementioned aggregate, An image data acquisition unit that acquires image data of a portion of the aforementioned aggregate, A switching unit that switches the destination of the assembly to the front of the kiln, A waste plastic processing system characterized by comprising the following features.

5. A method for evaluating waste plastics to determine their suitability as fuel for use in kilns, The steps include obtaining a set of data equivalent to the density of an aggregate of waste plastic fragments to be evaluated, the volume of each individual waste plastic fragment contained in the aggregate, and the surface area of ​​each fragment, A step of determining whether the assembly can be used as pre-fuel for a cement kiln based on the aforementioned set of data, If it is determined that the assembly can be used as fuel in front of the cement kiln, the step of controlling the assembly to send it to the front of the cement kiln is included. A method for evaluating waste plastics, characterized in that, in the step of making the determination, when the density of the aggregate is expressed as ρ, the volume of each individual waste plastic piece contained in the aggregate as Vn, and the surface area as Sn, an index based on the numerical value An = ρ・Vn / Sn is used to determine if a predetermined proportion or more of the waste plastic pieces have a numerical value An of 0.1 or less than a first threshold, and the aggregate is deemed usable as pre-fuel for a cement kiln.

6. A method for disposing of waste plastics, The steps include measuring the weight of a portion of the waste plastic fragments sampled from the collection to be evaluated, The steps include: acquiring image data of a portion of the aforementioned collection; Based on the measurement results of the step of measuring the weight and the acquisition results of the step of acquiring the image data, a step of acquiring a set of data equivalent to the density of the aggregate, the volume of each individual piece of waste plastic contained in the aggregate, and the surface area, A step of determining whether the assembly can be used as pre-fuel for a cement kiln based on the aforementioned set of data, A method for processing waste plastics, characterized by including the step of switching the destination of the aggregate to the front of a cement kiln if it is determined that the aggregate can be used as fuel in front of a cement kiln.

7. This is an evaluation program for waste plastics to determine their suitability as fuel for use in kilns. A process to obtain a set of data equivalent to the density of an aggregate of waste plastic fragments to be evaluated, the volume of each individual waste plastic fragment contained in the aggregate, and the surface area; A process to determine whether the assembly can be used as pre-fuel for a cement kiln based on the aforementioned set of data, If it is determined that the assembly can be used as fuel in front of the cement kiln, the computer is instructed to perform a process to send the assembly to the front of the cement kiln. A waste plastic evaluation program characterized in that, in the process of making the determination, when the density of the aggregate is expressed as ρ, the volume of each individual waste plastic piece contained in the aggregate as Vn, and the surface area as Sn, an index based on the numerical value An = ρ・Vn / Sn is used to determine that the aggregate can be used as pre-fuel for a cement kiln if a predetermined proportion or more of the waste plastic pieces have a numerical value An of ρ・Vn / Sn or less than a first threshold.

8. A waste plastic processing program, A process to measure the weight of a portion of the waste plastic fragments sampled from the aggregate to be evaluated, A process for obtaining image data of a portion of the aforementioned collection, Based on the measurement results of the weight measurement process and the acquisition results of the image data acquisition process, a process is performed to acquire a set of data equivalent to the density of the aggregate, the volume of each individual waste plastic piece contained in the aggregate, and the surface area. A process to determine whether the assembly can be used as pre-fuel for a cement kiln based on the aforementioned set of data, A waste plastic processing program characterized by causing a computer to perform the following steps: when it is determined that the aggregate can be used as fuel in front of a cement kiln, the destination of the aggregate is switched to the front of a cement kiln.

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