Waste plastic conveying device and waste plastic storage hopper

Abstract

The storage hopper (21) of the waste plastic conveying device has a pyramidal or conical portion. This conical or conical portion is provided with: a vertical stress Pv (kgf / m²) applied from the storage hopper (21) containing waste plastic (12) to the opening (56) at its lower end; a hopper angle θ (°); a cross-sectional area s (m²) of the opening (56); a perimeter length LO (m) of the opening (56); and a perimeter length L (m) of the upright main body at the upper end of the storage hopper. By observing the actual discharge result index G, and setting the aforementioned Pv, s, LO, and θ as variables, a formula representing the actual discharge result index G is derived. The calculated result of the formula is at or above a predetermined value, and the value of (s / LO) / L is at or above a predetermined value. This allows recycled waste plastic to be directly or with only light treatment loaded into the carbonization chamber.

Description

Technical Field

[0001] This invention relates to a waste plastic conveying device, and more particularly to a waste plastic conveying device and a waste plastic storage hopper for conveying waste plastic to be loaded into the carbonization chamber of a coke oven. Prior Technology

[0002] Background of the Invention The disposal of large quantities of waste plastics discharged as industrial and general plastic waste has historically involved landfilling most of it or incinerating a portion. However, waste plastics are difficult to decompose in landfills by soil microorganisms or bacteria, and incineration causes significant damage to incinerators due to the heat generated. Furthermore, the presence of chlorine in the waste plastics makes chlorine treatment in the exhaust gases problematic. Given the anticipated future shortage of landfill space and the rising environmental issues, promoting waste plastic recycling remains highly anticipated. In addition to reusing the plastics themselves, recycling methods include utilizing the heat from combustion, or using the gases or oils obtained from the thermal decomposition during heating as fuel or chemical feedstocks.

[0003] For example, document 1 (Japanese Patent Application Publication No. 2001-49261) discloses a method in which plastic granules formed at 100-160°C are mixed with coal and then dry-distilled in a coke oven to reuse waste plastic. On the other hand, document 2 (Japanese Patent Application Publication No. 2019-135278) describes that when a large amount of plastic is mixed, the strength of the resulting coke decreases. In order to keep the decrease in coke strength at around a few percent, the mass ratio of plastic to coal must be set to less than 1%. The amount that can be reused is limited by the target coke strength level.

[0004] As a method for processing waste plastics by adding them to a coke oven, there is a known method of loading waste plastics into a space above the coal already loaded into the carbonization chamber (hereinafter referred to as the "top space").

[0005] Reference 2 discloses the following method: After loading coke raw material, in which a blend of non-caking coal or slightly caking coal is made at a ratio of 30% or more by mass, into the carbonization chamber of a coke oven, waste plastic is loaded into the top space above the coke raw material for thermal decomposition and recovery. It is suggested that the waste plastic can be pre-formed into granules with a ratio of less than 20% by mass of sieve apertures smaller than 10 mm and a specific surface area of ​​less than 500 mm² / g. These granules are then loaded into the carbonization chamber to suppress rapid gas generation and recover a large amount of waste plastic. In the pre-forming of waste plastic, extrusion molding machines or twin-roll molding machines can be used.

[0006] According to document 3 (Japanese Patent Application Publication No. 2002-47494), in a method where coke raw material is first loaded into the carbonization chamber of a coke oven, and then waste plastic is loaded into the space at the top of the oven, most of the waste plastic can be thermally decomposed in the high-temperature coke oven. As a result, high-calorie thermally decomposed gases containing hydrogen, methane, ethane, propane, etc., can be obtained. These gases can be recovered by including them in the coke oven gases generated in the carbonization chamber of the coke oven through the thermal decomposition of coal, and can be reused as an energy source. In document 3, it is preferable to use waste plastic in a volume-reducing solidification process, employing waste plastic in a high-density block form. In an embodiment of the same document, a mixture of waste plastic is volume-reduced and solidified, using a composition with an average particle size of approximately 20 mm.

[0007] Document 4 (Japanese Patent Application Publication No. 4-41588) discloses a method in which waste plastic is loaded into the upper space of the carbonization chamber after the coal is dry distilled in a coking oven to produce coke. The same document also describes a method in which a hopper is installed in a loading vehicle and a cylindrical chute is set at the coking oven's feed port for loading of polymer waste in an atmosphere-isolated manner (see Figure 5 of the same document).

[0008] Document 5 (Japanese Patent Application Publication No. 10-237454) discloses a method in which a carbonization chamber in a coke oven is not loaded with coal. While heating this carbonization chamber to a predetermined temperature, waste plastic is loaded into the carbonization chamber for thermal decomposition, and the thermal decomposition gases are recovered together with the coke oven gases. According to Figure 1 of the same document, the waste plastic is loaded through a loading hopper and its lower damper in a carbon loading vehicle, and further through a charge hopper and its lower damper, before being loaded into the loading inlet.

[0009] Document 6 (Japanese Patent Application Publication No. 09-132780) discloses a method for loading coal and waste plastic into a coke oven as follows: waste plastic is fed into the feed hopper of a coke oven loading vehicle, followed by coal, and the loaded material is then extracted from the bottom of the feed hopper and loaded into the carbonization chamber. According to Figure 1 of the same document, a storage tank for waste plastic is located near the coal tower, and a metering hopper is located below it. First, waste plastic is fed from the metering hopper into the feed hopper of the coke oven loading vehicle. Then, a predetermined amount of coal is loaded from the coal tower 30 onto the waste plastic already loaded into the feed hopper using normal operation. Next, as shown in Figure 4, the material in the feed hopper, which contains waste plastic at the bottom and coal on top of it, is extracted and loaded into the carbonization chamber using the same operation as during normal material loading.

[0010] Document 7 (Japanese Patent Application Publication No. 2001-115163) discloses a method in which coal, waste plastic, and coal are fed into the feed hopper of a coal loading vehicle from below, and then the coal and waste plastic are loaded from the feed hopper into the carbonization chamber of a coke oven. Figure 1 shows a waste plastic trough for feeding waste plastic into the feed hopper and a coal trough for feeding coal. Summary of the Invention

[0011] Invention Summary In the method of processing waste plastic by loading it into the furnace top space 5 above the carbon 11 in the carbonization chamber 2 of the coke oven 1 (see Figure 10), a conveying device is required to transport the waste plastic 12 to be loaded into the carbonization chamber 2 to the furnace top of the coke oven. Typically, as shown in Figure 10, the waste plastic 12 is transported to the vicinity of the coke oven by a truck 45 or similar means, and the waste plastic 12 is fed from the truck 45 into the ground hopper 22. A furnace top hopper 23 for waste plastic can be installed on the furnace top of the coke oven. The number of furnace top hoppers 23 is the same as the number of loading inlets 4 arranged along the length of the carbonization chamber 2. Regarding the conveying of waste plastic 12 from the ground hopper 22 to the furnace hopper 23, the waste plastic 12 is taken out from the removal device 24 located at the bottom of the ground hopper 22, and then raised to the top of the coke oven by a flight conveyor 25, etc., and the necessary amount of waste plastic is removed to each furnace hopper 23 by the distribution removal device 26.

[0012] As a hopper for feeding waste plastic 12 through the loading inlet 4 of the carbonization chamber, a coal loading hopper already installed on the carbonization cart 41 can be used directly (see references 2, 6, 7), or a dedicated waste plastic loading hopper can be installed on the same carbonization cart 41 or on a movable trolley that is separately installed from the carbonization cart 41 and can move along the length of the furnace group (see references 4, 5). The number of both the feeding hopper and the loading hopper is the same as the number of loading inlets 4 along the length of the carbonization chamber.

[0013] Regarding the shape of the waste plastic to be loaded into the carbonization chamber, in Reference 2, the waste plastic is pre-formed into granules with a ratio of less than 20% by mass of particles smaller than 10 mm and a specific surface area of ​​less than 500 mm² / g before being loaded into the carbonization chamber. In Reference 3, it is preferable to use waste plastic that has undergone volume reduction and solidification, and to use waste plastic in the form of high-density lumps. In the embodiment of the same reference, the mixture of waste plastic is volume-reduced and solidified, and a composition with an average particle size of about 20 mm is used.

[0014] To pre-form or reduce the volume of recycled waste plastics, a processing device for volume reduction and curing becomes necessary. This increases processing costs. However, recycled waste plastics in their original state come in various sizes, have low volumetric density, and contain film-like substances. It is known that if waste plastics are pre-formed or reduced in volume, or even directly or with only slight treatment before being loaded into the carbonization chamber, conventional conveying devices often experience blockages. For example, in the waste plastic loading hopper (11) shown in Figure 1 of Document 5, the gate (13a) at its lower end experiences blockage due to its small opening. Furthermore, if the waste plastic storage tank (20) is shaped as shown in Figure 1 of Document 6, waste plastic accumulates at the bottom of the storage tank (20). The troughs or hoppers described in Figures 1 and 3 of Reference 7 have the following characteristics: the portion below the upright main body of the hopper with a narrowed cross-sectional area becomes a so-called "bridging" state, and the proper sequential descent of the material (plastic) is delayed, creating space in the lower part, resulting in a stagnation phenomenon in the continuous discharge.

[0015] The purpose of this invention is to provide a waste plastic conveying device, particularly a waste plastic conveying device and a waste plastic storage hopper: in the waste plastic conveying device used to convey waste plastic to be loaded into the carbonization chamber of a coke oven, even if the recycled waste plastic has been pre-shaped and volume-reduced, or even if it is loaded into the carbonization chamber directly or with only slight treatment, there will be no problem of the waste plastic blocking the conveying device.

[0016] That is, the essence of the present invention is as described below. [1] A waste plastic conveying device is used to supply waste plastic from an inlet located at the top of the carbonization chamber of a coke oven to the waste plastic inside the carbonization chamber. The aforementioned waste plastic conveying device has a waste plastic storage hopper midway through the conveying path. A portion of this storage hopper has a pyramidal, cylindrical, conical, or cylindrical surface that contacts the waste plastic. An opening is formed at the lower end of the aforementioned storage hopper. Let: the vertical stress Pv (kgf / m2) applied to the lower end of the aforementioned storage hopper containing waste plastic, tanθ calculated from the hopper angle θ (°), the cross-sectional area s (m2) of the aforementioned opening, the perimeter length LO (m) of the aforementioned opening, and the perimeter length L (m) of the upper end of the aforementioned storage hopper. The calculated result X, which is the actual result of tanθ, is above the predetermined value after substituting the actual result of tanθ into the formula representing the actual result of excretion. The value of (s / LO) / L is above the predetermined value. The actual result of excretion is obtained by observing the actual result of excretion.

[0017] The aforementioned relation is derived by taking the aforementioned Pv, (s / LO) based on the aforementioned s and LO, and the aforementioned tanθ as variables.

[0018] Furthermore, when the surface in contact with the waste plastic is the aforementioned pyramidal shape, the aforementioned hopper angle θ refers to the angle formed by the intersection of the face perpendicular to both the face and the horizontal plane with the horizontal plane. When the surface is the aforementioned conical shape, the aforementioned hopper angle θ refers to the angle formed by the intersection of the arbitrary face orthogonal to the aforementioned orthogonal plane with the horizontal plane when an arbitrary face (hereinafter referred to as "orthogonal face") is conceived. In the case of the aforementioned cylindrical or triangular shape, the aforementioned hopper angle θ is set to 90°.

[0019] [2] The waste plastic conveying device described in [1] is, wherein the aforementioned relationship is the following formula (1), and the value of X in formula (1) is 2.00 or more, and the value of (s / LO) / L is 0.025 or more. X=1123907·(Pv)-1.55·(s / LO)2·(tanθ)0.46(1)

[0020] [3] The waste plastic conveying device as described in [1] or [2] is characterized in that: the aforementioned storage hopper includes one or more of the following: ground hopper, furnace hopper, feeding hopper, and feed hopper.

[0021] [4] The waste plastic conveying device described in [3] is characterized in that: a waste plastic feeder is provided at the lower end of one or more of the above-ground hopper, furnace hopper, input hopper and feed hopper, wherein the waste plastic feeder is any one of screw feeder, circle feeder, table feeder, rake feeder and apron feeder.

[0022] [5] A waste plastic storage hopper for use in the waste plastic conveying device described in any one of [1] to [4].

[0023] This invention relates to a storage hopper used in a conveying device for supplying waste plastics from an inlet located at the top of the carbonization chamber of a coke oven. By designing a hopper with a pyramidal or conical portion on the surface in contact with the waste plastic, and satisfying an arbitrary discharge shape defined by a predetermined angle θ and a discharge outlet cross-sectional area s / discharge outlet perimeter length LO, it becomes possible to load recycled waste plastics into the carbonization chamber even after pre-forming and volume reduction treatment, or even directly or with only mild treatment. Simple Explanation of the Diagram

[0024] Figure 1A is a plan view showing an example of a storage hopper. Figure 1B shows an example of a storage hopper, and is a front cross-sectional view from the perspective of arrow BB in Figure 1A. Figure 2A is a plan view showing one example of a storage hopper. Figure 2B shows an example of a storage hopper, and is a front cross-sectional view from the perspective of arrow BB in Figure 2A. Figure 3A is a plan view showing an example of a storage hopper equipped with a screw feeder. Figure 3B shows an example of a storage hopper equipped with a screw feeder, and is a front cross-sectional view from the perspective of arrow BB in Figure 3A. Figure 4A is a plan view showing an example of a storage hopper equipped with a circular feeder. Figure 4B shows an example of a storage hopper equipped with a circular feeder, and is a front cross-sectional view from the perspective of arrow BB in Figure 4A. Figure 5A is a plan view showing an example of a storage hopper equipped with a benchtop feeder. Figure 5B shows an example of a storage hopper equipped with a benchtop feeder, and is a front cross-sectional view from the perspective of arrow BB in Figure 5A. Figure 6 is a front cross-sectional view showing an example of a storage hopper equipped with a rake feeder. Figure 7 is a front cross-sectional view showing an example of a storage hopper equipped with a skirted feeder. Figure 8 is a diagram showing an example of a conveying device for waste plastic in a coke oven. Figure 9 is a diagram showing an example of a conveying device for waste plastics in a coke oven. Figure 10 is a diagram showing an example of a conveying device for waste plastic in a coke oven. Figure 11 is a perspective view showing an example of a storage hopper. Figure 12 is a graph showing the relationship between the calculated value of the discharge index X and the actual discharge result index G. Figure 13 is a graph showing the relationship between the hopper angle θ and the actual discharge result index G. Figure 14 is a graph showing the relationship between (s / LO) / L and the actual excretion result index G. Implementation

[0025] Implementation form of the invention This invention relates to a waste plastic conveying device (see Figure 10) and a waste plastic storage hopper used in the aforementioned waste plastic conveying device. The waste plastic conveying device is used to supply waste plastic 12 from the loading inlet 4 at the top of the carbonization chamber 2, which is installed in the coke oven 1. The conveying device of this invention has a storage hopper capable of temporarily storing various types of waste plastic, and a feeder that efficiently discharges / supplyes waste plastic from the storage hopper to the next step. As for the shape of the waste plastic 12 to be loaded into the carbonization chamber 2, conventionally, as mentioned above, it is mostly constructed by pre-forming or volume-reducing and solidifying recycled waste plastic. However, as a new waste plastic processing method to be established in the future, there are also processes being explored such as breaking it into irregular shapes of about 30 mm to simplify pre-processing as much as possible. To avoid pre-forming and volume-reducing curing processes using extruders and twin-roll molding machines, the waste plastic, even after crushing, retains its original shape. It is known that if waste plastic has undergone pre-forming and volume-reducing processes, or is directly or only lightly processed before being loaded into the carbonization chamber, conventional conveying systems often experience blockages due to the waste plastic.

[0026] As mentioned above, the conveying device that transports the waste plastic to be loaded into the carbonization chamber 2 to the furnace of the coke oven 1 and further loads the waste plastic into the carbonization chamber is configured as shown in Figures 8-10, including a ground hopper 22, a furnace hopper 23, a feeding hopper 43, and a feed hopper 42. The aforementioned ground hopper 22 is the hopper on the ground (initially supplied with waste plastic from the outside via trucks, etc.), and the aforementioned furnace hopper 23 is the hopper at the top of the coke oven (initially supplied with waste plastic to be loaded into the coke oven). The waste plastic storage hopper 43 (which is separate from the coal and dedicated to waste plastic, used to prepare and store the amount of waste plastic required for each predetermined loading inlet, and fed into the carbonization chamber through the loading inlet 4) and the feed hopper 42 (which is shared with the coal and, like the waste plastic storage hopper 43, used to prepare and store waste plastic, and fed into the carbonization chamber through the loading inlet 4) are collectively referred to as the waste plastic storage hopper 21. That is, the waste plastic conveying device of the present invention has a waste plastic storage hopper 21 midway along the conveying path.

[0027] The storage hopper 21 has the following shape: a cylindrical portion at the top, and a pyramidal, cylindrical, conical, or cylindrical portion at the bottom. That is, the storage hopper has a portion where the surface in contact with the waste plastic is pyramidal, cylindrical, conical, or cylindrical. Since the cross-sectional area of ​​a pyramid or cone decreases towards the bottom, and it has a flat portion at the bottom, strictly speaking, a pyramid can be called a truncated pyramid, and a cone can be called a truncated cone.

[0028] Secondly, the angle of inclination (hopper angle θ) of the surface constituting the pyramid or cone is defined. Furthermore, in the case of a cylindrical or triangular shape, the hopper angle θ will be 90°. Also, the hopper angle θ is defined as exceeding 90° when the surface 51 being the object is overhanging.

[0029] Figures 1A and 1B illustrate the pyramidal form. In the case of a quadrangular pyramid, there are four faces 51 constituting the pyramid. Figure 1A shows the hopper from below (from the lower end 55 of the pyramid), with dotted lines representing the opening 56 of the lower end 55 of the pyramid. In this invention, the angle formed by the line 54 of the intersection of the face perpendicular to both the face (face 51 in Figure 1) and the horizontal plane 52 with the horizontal plane 52 is defined as the hopper angle θ. In the example of Figure 1, the faces 51 are the left face 51A, the right face 51B, the upper face 51C, and the lower face 51D of Figure 1A. In the following description, the left face 51A will be used. In Figure 1, the plane perpendicular to both surface 51A and horizontal surface 52 is designated as orthogonal surface 53. The intersection line 54 of orthogonal surface 53 and surface 51A is determined, and the angle between intersection line 54 and horizontal surface 52 becomes the hopper angle θA. Section BB represents the orthogonal surface 53 of surface 51. In Figure 1B, horizontal surface 52 is shown as a straight line. In Figure 1B, the hopper angle θ of surface 51B is θB. The hopper angles θC and θD can be calculated similarly for surfaces 51C and 51D.

[0030] The conical shape will be explained using Figures 2A and 2B. Figure 2A is a view of the hopper from below (from the lower end 55 of the cone), and the opening 56 of the lower end 55 of the cone is indicated by dotted lines. The surface 51 constituting the cone is formed by a curved surface. In this invention, when a surface (orthogonal surface 53) is envisioned that is orthogonal to any part of the surface constituting the cone and perpendicular to the horizontal plane 52, the angle formed by the line of intersection of this arbitrary surface and the orthogonal surface 53 and the horizontal plane is defined as the hopper angle θ. In the example shown in Figure 2, a portion of surface 51 (surface 51A, which includes the intersection line 54 in Figure 2) is used as an arbitrary surface. This surface 51A is taken as surface 51. An orthogonal surface 53 is imagined to be perpendicular to surface 51A and the horizontal surface 52. The intersection line 54 of surface 51A and the orthogonal surface 53 is determined, and the angle between the intersection line 54 and the horizontal surface 52 is set as the hopper angle θ (θA). In Figure 2, section BB represents the orthogonal surface 53 of surface 51. In Figure 2B, the horizontal surface 52 is shown as a straight line. In the example shown in Figure 2, the hopper angle θA of surface 51A in the left direction of the circumference of the cone in Figure 2A is explained. The hopper angle θ can be calculated similarly for any direction on the circumference of the cone. Furthermore, in the plan view, when the centroid of the opening shape of the upper end 57 of the inverted truncated cone is different from that of the opening shape of the lower end 55, the hopper angle θ will be the smallest when the length of the intersection line 54 is longest when projected onto the plan view in the circumferential direction. Therefore, to find the minimum value of the hopper angle θ, it is only necessary to calculate the hopper angle θ at the position where the length of the intersection line 54 is longest when projected onto the plan view.

[0031] A retrieval device is provided at the lower end 55 of the storage hopper 21. An opening 56 is formed at the lower end 55 of the storage hopper 21. The dotted shaded areas in Figures 1A and 2A represent the opening 56. In conventional devices, the opening 56 at the lower end 55 of the storage hopper 21 is smaller due to the smaller cross-sectional area of ​​the retrieval device connection. A pyramidal or conical shape is provided at the lower part of the storage hopper 21. For this purpose, a pyramidal or conical shape is provided. Regarding the aforementioned hopper angle θ, an angle of approximately 60 to 90° has been conventionally used. When using conventionally pre-molded or volume-reduced cured waste plastic as waste plastic 12, such a pyramidal or conical shaped storage hopper is used. In response, when using pre-molded, volume-reduced, and cured waste plastics, or even when using waste plastics directly or with only mild treatment, there are instances where waste plastics clog the storage hoppers in conventionally shaped containers.

[0032] Therefore, it was conceivable that the above problem could be solved if the vertical stress Pv applied to the lower end 55 of the storage hopper 21 containing waste plastic, the hopper angle θ, and the shape of the opening 56 of the lower end 55, all within the conical or pyramidal shape of the storage hopper 21, met predetermined relationships. Therefore, it was decided to quantify the influence of these factors through model experiments. Model experiments were conducted with various changes to Pv, θ, and the discharge outlet size, and differences in discharge performance were observed. Furthermore, experiments were performed in both the model and the actual machine to confirm discharge performance while changing the discharge outlet size.

[0033] Here, the discharge performance index G is defined for the discharge status from the storage hopper in the following manner. G=1: Immediately block and eliminate delay. Although some waste plastic is discharged, it remains in the hopper and the zero discharge rate continues, so the total amount is not discharged. G=2: Even with the interaction of stagnation and discharge, discharge still occurs in some way. Even if a zero discharge rate is temporarily observed, the total amount will eventually be discharged naturally. G=3: Although the drainage process may sometimes be slightly slower, there is no blockage. While changes in discharge speed can be observed, there is no continuous zero discharge speed for a certain period of time, resulting in almost continuous discharge of the entire volume. G=4: Stable discharge continues The discharge rate is achieved continuously and steadily in a free-fall manner without any delay, ensuring the discharge of the entire volume.

[0034] As long as the actual excretion result index G is above 2, it can be judged as good excretion.

[0035] The vertical stress Pv (unit: kgf / m2) applied to the lower end 55 of the storage hopper 21 can be obtained by the following formula (2), which is derived from Jansen's formula (refer to reference 8 (Chemical Engineering Handbook, revised 5th edition, published on March 18, 1963, pp. 868-869)). Imagine the storage hopper 21 shown in Figure 11, and set the cross-sectional area of ​​the upper end 57 of the storage hopper 21 (c×d in the example of Figure 11) as the cross-sectional area A (m2) of the upright main body, and set the perimeter length of the upper end 57 (2(c+d) in the example of Figure 11) as the perimeter length L (m) of the upright main body. Also, set the total height of the storage hopper 21 (hs+hc in the example of Figure 11) as the total height h (m), and set ρ as the filling density of waste plastic (kg / m3) and k as the coefficient (kg / kgf). Pv=ρ·((A / L) / k)·(1-exp(-1 / ((A / L) / k)‧h))) (2)

[0036] While changing the height h of the waste plastic layered in the mold hopper, the vertical stress applied to the lower surface is measured, and the coefficient k is determined according to the above formula. That is, k = 0.07 kg / kgf.

[0037] Furthermore, the cross-sectional area of ​​the lower end 55 of the storage hopper 21 shown in Figure 11 (a×b in the example of Figure 11) is set as the opening cross-sectional area s (m2), and the perimeter length of the lower end 55 (2(a+b) in the example of Figure 11) is set as the opening perimeter length LO (m). Regarding the shape of the opening 56 of the lower end 55 of the storage hopper 21, the index s / LO is set based on the cross-sectional area s and the perimeter length LO of the opening 56. Moreover, the hopper angle is set as the index tanθ. Then, the actual discharge result index G obtained through the above model experiment is regressed using Pv, s / LO, and tanθ, resulting in a strong correlation, and a regression formula representing G is obtained. G=f·(Pv)p·(s / LO)q·(tanθ)r(3) f, p, q, and r are regression coefficients.

[0038] Then, the results of the experiment showed that when the vertical stress Pv applied to the opening at the lower end of the storage hopper, the tanθ calculated from the hopper angle θ, and the cross-sectional area s of the aforementioned opening / the perimeter length LO of the aforementioned opening are determined to satisfy a predetermined relationship, even if pre-forming and volume reduction curing treatment is performed, and even if waste plastic with an irregular shape of about 30mm is used without pre-forming and volume reduction curing treatment, the blockage and bridging of waste plastic 12 in the storage hopper 21 can be prevented.

[0039] Preferably, the aforementioned predetermined method is determined by considering the discharge limit indicators that can stably discharge waste plastics.

[0040] The following is a detailed explanation.

[0041] A hopper experiment was conducted using a model of the storage hopper 21 shown in Figure 11. As shown in Table 1, waste plastic molded materials were filled with various modified hopper shapes, and the discharge performance of the waste plastic with the opening open was observed to determine the actual discharge performance index G. The experimental data are shown in Table 1. [Table 1]

[0042] In this regard, the variables (Pv) under each condition are calculated according to the aforementioned equation (2) and shown in Table 1. Furthermore, (s / LO) and (tanθ) are obtained. Using the combination of these multiple data, the actual results of excretion are observed as the aforementioned excretion actual result index G. Based on the aforementioned Pv, the aforementioned s, LO, (s / LO), and the aforementioned tanθ, the relationship representing the excretion actual result index G is derived as the following equation (3). G=f·(Pv)p·(s / LO)q·(tanθ)r(3)

[0043] Next, a complex regression calculation is performed on the above equation (3) to determine the coefficients f, p, q, and r. The coefficients are approximately f=1123907, p=-1.55, q=2, and r=0.46.

[0044] Therefore, the coefficients of the above complex regression calculation results are substituted into f, p, q, r on the right side of the above equation (3), and the left side of equation (3) is set as X to derive the following equation (1). X=1123907·(Pv)-1.55·(s / LO)2·(tanθ)0.46(1)

[0045] The analysis results are shown in Figure 12. The vertical axis of Figure 12 is the actual discharge performance index G determined by the experiment, and the horizontal axis X is the discharge index calculated on the right side of Equation (1) using the variables Pv, S / L, and tanθ determined by the coefficients of the above equation and the experimental conditions. The correlation coefficient between G and X is good, around 0.9. Then, it becomes possible to review the hopper shape that ensures discharge performance by adjusting each factor to X ≥ 2.00. Furthermore, it becomes possible to make a hopper shape with better discharge performance by adjusting each factor to X ≥ 2.50. It is better to set X ≥ 3.00. It is advisable to set the upper limit of X to 6.00.

[0046] Figure 13 is a graph extracting the relationship between the hopper angle θ and the actual discharge performance index G from the experimental data in Table 1. When θ < 60°, G = 1, which cannot guarantee discharge. Therefore, θ ≥ 60° is preferable to ensure discharge. Furthermore, θ ≤ 75° is even better.

[0047] Furthermore, the relationship between s / LO and discharge performance was explored in relation to the size of the discharge outlet. However, as the dimensions c and d of the upper end (upright main body) of the storage hopper increase from 1m for small, 2m for medium, and 4m for large, the s / LO required to ensure discharge tends to increase. This is because the vertical stress Pv applied to the discharge outlet proportional to the size of the hopper increases. To reflect this effect, Figure 14 shows a dimensionless relationship between s / LO and the perimeter length L of the upper end of the storage hopper. In Figure 14, for the size of the storage hopper, small is represented by ○, medium by ◇, and large by □. It is known that discharge cannot be ensured when (s / LO) / L < 0.025. Therefore, to ensure discharge, it is preferable that (s / LO) / L ≥ 0.025. The upper limit of (s / LO) / L should be set to 0.035.

[0048] A take-out device 24 for removing waste plastic is provided at the lower end 55 of the waste plastic storage hopper 21. The shape of the opening 56 at the lower end 55 of the storage hopper 21 is determined according to the size of the take-out device 24 and the size of the waste plastic being removed. Conventionally, shapes with ((s / LO) / L) less than 0.025 and the left-hand side X of formula (1) less than 2 are used. When waste plastic of irregular shape, broken into about 30 mm, is used without pre-forming and volume reduction curing treatment, it may contain film-like shapes, and these film-like shapes may expand and cause blockage at the opening 56 at the lower end of the storage hopper. In this invention, by specifying the value of (s / LO) / L and the left-hand side X of formula (1) as described above, even when using waste plastic of irregular shape, broken into about 30 mm, without pre-forming and volume reduction curing treatment, blockage at the lower end of the storage hopper can be ideally prevented.

[0049] As mentioned above, the storage hopper 21 of the present invention includes one or both of a ground hopper 22 for waste plastic and a furnace hopper 23 for waste plastic. Furthermore, the storage hopper 21 of the present invention can be used as a feeding hopper 42 or an input hopper 43 mounted on a carbon loading cart 41 or a movable trolley separately configured to move along the length of the furnace group (see Figures 8 and 9).

[0050] The storage hopper 21 of the present invention is designed with the following predetermined relationship between tanθ (calculated from the hopper angle θ of the pyramidal or conical portion), the cross-sectional area s of the opening, the perimeter length LO of the opening, the perimeter length L of the upper end of the storage hopper (i.e., (s / LO) / L), and the vertical stress Pv applied to the opening at the lower end, thereby achieving good results. Since the shape of the opening 56 at the lower end 55 of the storage hopper 21 is more stable than in the past, ensuring a stable discharge state, the extraction device 24 located below the lower end 55 of the storage hopper 21 must also be able to handle the size of the waste plastic discharged from such a large opening. In this invention, this problem can be solved by using any one of the following: a screw feeder 31, a circular feeder 32, a benchtop feeder 33, a rake feeder 34, or a skirt feeder 35 for the waste plastic removal device 24 located at the lower end of one or more of the waste plastic hoppers 22, 23, 43, and 42.

[0051] As shown in Figures 3A and 3B, the screw feeder 31 can handle situations where the lower end 55 of the storage hopper 21 has a large opening 56. Figures 3A and 3B show an example of the screw feeder 31 being configured as a take-out device 24 in the storage hopper 21, which is a furnace hopper 23 (see Figure 8). The waste plastic stored in the furnace hopper 23 is taken out by the screw feeder 31 and put into the feed hopper or the feed hopper located below the take-out outlet 28. As an example of satisfying the requirements of the present invention, the following can be exemplified: θ=70°, tanθ=2.8, Pv=433kgf / m2, s=0.25m2, LO=2m, (s / LO) / L=0.03, and X=2.3 on the left side of equation (1).

[0052] As shown in Figures 4A and 4B, the circular feeder 32 has a bottom panel 37 and blades 36 arranged around the opening 56 at the lower end 55 of the storage hopper 21. The blades 36 rotate with the rotation of the bottom panel 37, and the waste plastic is moved to the take-out outlet 28 by the blades 36 and fed vertically downward from the take-out outlet 28. This makes it possible to handle cases where the lower end of the storage hopper has a large opening. Figures 4A and 4B show an example of the circular feeder 32 being configured as a take-out device 24 in the storage hopper 21, which is a ground hopper 22 (refer to Figures 8 and 9). The circular feeder 32 takes out the waste plastic stored in the ground hopper 22 and transports it to the furnace of the coke oven via the ladder conveyor 25 shown in Figures 8 and 9 through the take-out outlet 28. Examples of fulfilling the requirements of the present invention include: θ=80°, tanθ=6.0, Pv=452kgf / m2, s=0.25m2, LO=2m, (s / LO) / L=0.03, and X=3.1 on the left side of equation (1).

[0053] As shown in Figures 5A and 5B, the benchtop feeder 33 has a rotating bottom plate 37 at the opening 56 of the lower end 55 of the storage hopper 21. The rotating bottom plate 37 causes the waste plastic to be thrown in a circumferential direction and fed parallel to the outlet 28 from the opening 38. This allows for handling situations where the lower end 55 of the storage hopper 21 has a large opening 56. Figures 5A and 5B show an example of the benchtop feeder 33 configured as a take-out device 24 in the storage hopper 21, which serves as the furnace hopper 23 (refer to Figure 9). The waste plastic stored in the furnace hopper 23 is taken out by the benchtop feeder 33 and fed into the feed hopper located below the outlet 28 or into the feed hopper. Examples of fulfilling the requirements of the present invention include: θ=73°, tanθ=3.3, Pv=373kgf / m2, s=0.25m2, LO=2m, (s / LO) / L=0.04, and X=3.1 on the left side of equation (1).

[0054] As shown in Figure 6, the rake feeder 34 is an opening 56 located at the lower end 55 of the storage hopper 21. An actuating cylinder is provided on one side of the opening 56, and a sliding plate 341 is attached to the cylinder. A scraper 342 is provided on the sliding plate, which is perpendicular to the forward direction of the sliding plate 341 and inclined to the backward direction. The sliding plate 341 slides in conjunction with the forward and backward movement of the cylinder, and feeds the waste plastic from the cylinder side of the opening 56 to the opposite side. This makes it possible to handle situations where the lower end 55 of the storage hopper has a large opening 56. Examples of satisfying the requirements of the present invention include: θ=85°, tanθ=12, Pv=1350kgf / m2, s=12.3m2, LO=14m, (s / LO) / L=0.055, and X>4 on the left side of equation (1).

[0055] As shown in Figure 7, the skirt-type feeder 35 is a feed conveyor 39 located at the opening 56 of the lower end 55 of the storage hopper 21. The waste plastic can be moved in conjunction with the movement of the feed conveyor 39. This makes it possible to handle situations where the lower end 55 of the storage hopper 21 has a large opening 56. Examples of fulfilling the requirements of the present invention include: θ = 76°, tanθ = 4, Pv = 784 kgf / m², s = 2.3 m², LO = 6 m, (s / LO) / L = 0.047, and X > 4 on the left side of equation (1).

[0056] In the examples shown in Figures 8 and 9, a circular feeder 32 is used as the device for removing waste plastic located at the lower end of the storage hopper 21, i.e., the above-ground hopper 22. Furthermore, as the device for removing waste plastic located at the lower end of the storage hopper 21, i.e., the furnace hopper 23, a screw feeder 31 is used in the example shown in Figure 8, and a benchtop feeder 33 is used in the example shown in Figure 9.

[0057] Waste plastic stored in the furnace hopper can be supplied to a hopper for feeding waste plastic into the carbonization chamber located in the carbonization car, and the waste plastic will be loaded into the carbonization chamber from the hopper through the carbonization chamber's loading inlet.

[0058] The following describes the case where a dedicated feeding hopper 43 for loading waste plastic into the loading inlet 4 of the carbonization chamber 2 is provided. As shown in FIG8, the feeding hopper 43 is provided on the carbonization cart 41 or a movable trolley that is different from the carbonization cart 41 and can move along the length of the furnace group. The number of feeding hoppers 43 is the same as the number of loading inlets along the length of the carbonization chamber. Similar to the storage hopper 21 of the present invention described above, this feeding hopper 43 has a portion in which the surface in contact with the waste plastic is pyramidal or conical. The value of the left side X of the aforementioned equation (1) is set to a predetermined value or higher based on the relationship between the hopper angle θ, the vertical stress Pv applied to the opening, and the cross-sectional area S of the opening / the perimeter length L of the opening. This allows the effects of the present invention to be achieved. The predetermined value of the left side X of the equation is set to 2 or higher, preferably 2.5 or higher, and more preferably 3 or higher. This prevents the waste plastic from clogging or bridging in the feed hopper. In the example shown in Figure 8, a screw feeder 31 is used as the waste plastic removal device located at the lower end of the storage hopper 21, which is the feed hopper 43. Furthermore, even if the hopper angle θ formed by each surface of the storage hopper is different, as long as the value of X on the left side of the aforementioned equation (1) is within a favorable range at the position where the hopper angle θ is at its minimum.

[0059] As a hopper for feeding waste plastic into the carbonization chamber, the following explanation will focus on the case where the feed hopper 42 for loading coal, which is installed on the carbonization cart 41, is modified for use, as shown in FIG. 9. The storage hopper 21 of the feed hopper 42 should have the same conditions as the feed hopper 43 for loading waste plastic, which is installed on the carbonization cart 41. In the example shown in FIG. 9, a benchtop feeder 33 is used as the extraction device located at the lower end of the feed hopper 42.

[0060] 1: Coke oven 2: Carbonization Chamber 4: Fill the inlet 5: Furnace top space 11: Load carbon 12: Waste Plastic 21: Storage hopper 22: Ground hopper 23: Furnace hopper 24: Removal device 25: Ladder conveyor 26: Dispensing and dispensing device 28: Take the exit 31: Screw feeder 32: Circular feeder 33: Tabletop Feeder 34: Rake Feeder 341: Sliding plate 342: Scraper 35: Skirt-type feeder 36: Blade plate 37: Bottom panel 38: Opening 39: Feed Conveyor 41: Carbon loading vehicle 42: Feed hopper 43: Feed into the hopper 45: Truck 51, 51A, 51B, 51C, 51D: Face 52: Horizontal plane 53: Orthogonal plane 54: Intersection 55: Lower end 56: Opening 57: Upper end A: Cross-sectional area of ​​the upright main body BB: Section a, b, c, d: Length G: Excretory Actual Outcome Index h: Total height (height) hc, hs: height L: Perimeter length of the upper end LO: Perimeter length of the opening Pv: Vertical stress s: Cross-sectional area of ​​the opening X: Calculated value of emission index θ,θA,θB,θC,θD: Hopper angles

Claims

1. A waste plastic conveying device for supplying waste plastic from an inlet located at the top of a coke oven carbonization chamber to the carbonization chamber, wherein the waste plastic conveying device has a waste plastic storage hopper in the middle of the conveying path, wherein a portion of the storage hopper has a pyramidal or conical surface in contact with the waste plastic, and an opening is formed at the lower end of the storage hopper. The relationship between the vertical stress Pv (kgf / m2) applied to the lower end of the storage hopper containing the waste plastic, tanθ calculated from the hopper angle θ (°), the cross-sectional area s (m2) of the opening, the perimeter length LO (m) of the opening, and the perimeter length L (m) of the upper end of the storage hopper, representing the actual discharge result index obtained by observing the actual discharge result, is set as the following formula (1). Substituting the actual result of tanθ into equation (1), the calculated result X is 2.00 or more, and the value of (s / LO) / L is 0.025 or more. X = 1123907・(Pv)-1.55・(s / LO)2・(tanθ)0.46 (1) Furthermore, when the surface in contact with the waste plastic is the aforementioned pyramidal shape, the aforementioned hopper angle θ refers to the angle formed by the intersection of the face perpendicular to both the face and the horizontal plane and the horizontal plane. When it is the aforementioned conical shape, the aforementioned hopper angle θ refers to the angle formed by the intersection of the face perpendicular to both the face and the horizontal plane (hereinafter referred to as "orthogonal face") with the aforementioned orthogonal face when an orthogonal face (hereinafter referred to as "orthogonal face") is assumed. Also, the aforementioned hopper angle θ is the value used at the position where the hopper angle is the smallest among the surfaces in contact with the waste plastic.

2. The waste plastic conveying device as claimed in claim 1, wherein the aforementioned storage hopper includes one or more of the following: ground hopper, furnace hopper, feed hopper, and feeding hopper.

3. The waste plastic conveying device as claimed in claim 2, wherein a waste plastic feeder is provided at the lower end of one or more of the aforementioned ground hopper, furnace hopper, input hopper, and feed hopper, wherein the aforementioned waste plastic feeder is any one of a screw feeder, a circular feeder, a table feeder, a rake feeder, or a skirt feeder.

4. A waste plastic storage hopper, which can be used in the waste plastic conveying device as claimed in claim 1.

5. A waste plastic storage hopper, which can be used in the waste plastic conveying device as claimed in claim 2.

Images