JP5207475B2 - How to use resin waste - Google Patents

Description

  The present invention relates to a method for utilizing resinous waste, and in particular, while using resinous waste as a fuel for burning cement, residual organic pollutants such as dioxins (DXNs) contained in cement kiln combustion exhaust gas ( The present invention relates to a method of keeping the amount of POPs) low.

  In recent years, recycling of wastes into cement raw materials and fuels has been promoted, and as the amount of waste processing increases, harmful substances such as POPs such as DXNs and volatile organic compounds (VOC) in cement kiln combustion exhaust gas There is concern about an increase in the amount of emissions.

  However, it is extremely difficult to remove harmful substances contained in cement kiln exhaust gas at a low concentration from a large amount of exhaust gas. If the concentration of harmful substances in cement kiln exhaust gas increases, it may cause air pollution. In addition, there is a risk that it may become an obstacle to the expansion of the use of recycled resources such as fly ash.

  Therefore, for example, the combustion exhaust gas treatment method described in Patent Document 1 is not yet effective for reducing the concentration of harmful substances such as mercury and dioxins in combustion exhaust gas such as cement kiln exhaust gas while effectively using coal ash. While selecting coal ash having a fuel carbon content of 1% by mass or more, blowing the coal ash into the combustion exhaust gas, adsorbing the harmful substances in the combustion exhaust gas, recovering the coal ash adsorbing the harmful substances, The temperature of the combustion exhaust gas at the ash blowing position is set to 160 ° C. or less to prevent resorption of mercury adsorbed on unburned carbon and resynthesis of dioxins.

  In addition, in Patent Document 2, when manufacturing cement, in order to prevent accumulation of harmful substances such as mercury and dioxin in the facility, piping from the preheater to the chimney or A method is disclosed in which a part of an exhaust gas having a temperature of 350 ° C. or higher circulating in the apparatus is extracted, and harmful substances such as mercury and dioxin contained in the gas are condensed and removed.

JP 2008-237959 A JP 2005-097005 A

  As described above, various measures for reducing POPs in cement kiln combustion exhaust gas have been proposed in the past, but there is no measure in relation to resin waste such as waste plastic that has been used effectively as a fuel for conventional cement firing. It was not applied and there was room for improvement.

  Therefore, the present invention has been made from the above viewpoint, and it is possible to keep the amount of POPs contained in cement kiln combustion exhaust gas low while using resin waste such as waste plastic as a fuel for cement firing. Let it be an issue.

  In order to solve the above-mentioned problems, the present inventors have conducted intensive research, and as a result, conventionally, resin-based waste received in cement factories is mainly used in terms of ease of combustion due to its size. Reviewing the current situation of selecting the use position in Japan, focusing on the fact that various resin wastes have different degradability, the use position in cement manufacturing equipment based on the decomposability of resin waste As a result, it was found that the above-mentioned problems can be solved, and the present invention has been made.

  That is, the present invention is a method for utilizing resinous waste, in which waste plastic containing 50% by mass or more of aromatic resin is blown from a burner in front of a kiln of a cement kiln, and waste containing 90% by mass or more of aliphatic resin. The plastic is put into a kiln bottom of a cement kiln or / and a calcining furnace.

  According to the present invention, incomplete combustion can be prevented by burning waste plastic containing an aromatic resin having a hardly-decomposable monocyclic / polycyclic aromatic structure in the front part of the cement kiln kiln. Therefore, recombination of DXNs due to incomplete combustion can be avoided in advance. Thereby, the generation amount of POPs can be reduced as compared with the conventional case where the use position is not selected depending on the type of resin.

  The present invention also relates to a method for using resinous waste, wherein the received resinous waste is separated into waste plastic containing an aromatic resin and waste plastic containing an aliphatic resin. Waste plastic containing 50 mass% or more of aliphatic resin is blown from the burner in front of the kiln of the cement kiln, and waste plastic containing 90 mass% or more of the sorted aliphatic resin is put into the kiln bottom or / and calcining furnace of the cement kiln. It is characterized by doing. According to the present invention, by separating the received various resin wastes into waste plastics containing aromatic resins and waste plastics containing aliphatic resins, a cement manufacturing apparatus is provided for each resin waste. Can be used at a suitable position.

  Furthermore, in the method of using the resin waste, the waste plastic containing the aromatic resin and the waste plastic containing the aliphatic resin can be separated using near infrared spectroscopy. Separation can be easily performed by using a portable sorting apparatus using near infrared spectroscopy.

  Further, in the above-mentioned method of using resin waste, waste plastic containing 50% by mass or more of the aromatic resin can be crushed, adjusted to a particle size of 3 mm or more and 20 mm or less, and blown from a burner in front of a cement kiln. Thereby, incomplete combustion can be prevented and the generation amount of POPs can be reduced more effectively.

  In the above-mentioned resin waste utilization method, waste plastic containing 90% by mass or more of the aliphatic resin is crushed, adjusted to a particle size of 5 mm to 50 mm, and put into a cement kiln bottom or / and calciner. can do. As a result, burnout is improved and heat energy can be efficiently recovered.

  As described above, according to the present invention, the amount of POPs contained in the cement kiln combustion exhaust gas can be kept low while using resin waste such as waste plastic as a fuel for cement firing.

It is a flowchart for demonstrating the utilization method of the resin waste concerning this invention.

  Next, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows an example of a cement baking apparatus that uses resin waste using the method according to the present invention. The cement baking apparatus 1 includes a preheater 2, a calcining furnace 3, a cement kiln 4, and a clinker. It consists of a cooler 5 and the like.

  Since the preheater 2 preheats the raw material with the high-temperature gas from the calcining furnace 3, the preheater 2 includes a plurality of cyclones 2a to 2d in multiple stages, between each cyclone, between the third-stage cyclone 2b and the calcining furnace 3, and at the top. Raw material chutes 7 to 11 are provided between the lower cyclone 2a and the cement kiln 4, and a main exhaust wind turbine 6 for discharging exhaust gas discharged from the uppermost cyclone 2d to the outside of the system is disposed.

  The calcining furnace 3 is provided with a burner 3a for blowing pulverized coal in order to calcine the raw material preheated by the preheater 2, and the calcination air from the clinker cooler 5 is introduced into the calcining furnace 3 through the cooler bleed duct 12. Is done. The calcining furnace 3 is connected to the cement kiln 4 via the rising duct 13.

  The cement kiln 4 includes a burner (burner before kiln) 4a for blowing pulverized coal in order to sinter the raw material calcined by the calcining furnace 3 to generate cement clinker. The clinker cooler 5 is disposed on the downstream side of the cement kiln 4 in order to cool the clinker fired as described above.

  In the cement baking apparatus 1, the exhaust gas of the cement kiln 4 includes POPs such as DXNs resulting from the use of waste as a cement raw material and fuel. The DXNs are re-synthesized by incomplete combustion of an aromatic resin having a hardly-decomposable monocyclic / polycyclic aromatic structure.

  Therefore, in the present invention, waste plastic containing 50% by mass or more of aromatic resin (hereinafter referred to as “waste plastic”) is blown from the kiln burner 4a of the cement kiln 4 so that the maximum temperature in the cement kiln 4 is 1450 ° C. Cement kiln waste plastic containing 90% by mass or more of an aliphatic resin that is easily decomposable and has little risk of re-synthesis of DXNs, while preventing incomplete combustion by burning under high temperatures 4 is put into the kiln bottom 14 or the calcining furnace 3, or both. The kiln bottom part 14 is a part of the cement kiln 4 on the upstream side in the raw material flow direction, and the kiln front part 15 is a part of the cement kiln 4 on the downstream side of the raw material flow direction. In addition, it refers to the part where the pre-burner burner 4a for firing the raw material is installed.

  Specifically, waste plastic containing 50% by mass or more of aromatic resin can be blown into the cement kiln 4 from the burner 4a before the kiln 4 or a burner provided separately. On the other hand, waste plastic containing 90% by mass or more of aliphatic resin may be introduced into the calcining furnace 3 from the burner 3a or a separately provided burner, and is introduced into the kiln bottom 14 via a nozzle or the like, or opened and closed. A possible charging port may be provided in the kiln butt part 14 and directly charged into the kiln butt part 14.

  Before putting the waste plastic containing the aromatic resin and the waste plastic containing the aliphatic resin into the cement kiln 4, the calcining furnace 3, etc., these can be crushed in advance to adjust the particle size.

  Waste plastic containing 50% by mass or more of aromatic resin can be crushed and adjusted in particle size to prevent incomplete combustion and reduce the amount of POPs generated more effectively. By adjusting, it can be injected from the cement kiln 4 as the main fuel for the burner before the kiln. If the particle size is less than 3 mm, the power required for crushing is excessive, which is not preferable. If it exceeds 20 mm, POPs may be generated due to incomplete combustion.

  In addition, waste plastic containing 90% by mass or more of aliphatic resin can be crushed and adjusted in particle size so that it can be burned out and heat energy can be recovered efficiently, and the particle size is adjusted to 5 mm to 50 mm. Then, it can be put into the kiln bottom 14 or the like. If the particle size is less than 5 mm, the amount of crushing treatment decreases and the power source unit increases, which is not preferable. If it exceeds 50 mm, the burnout is worsened and the heat is recovered at the top of the preheater and the heat energy recovery efficiency decreases. There is a problem that.

  In addition, since various resin wastes are carried into the cement factory equipped with the cement baking apparatus 1, the received resin wastes are disposed of as waste plastics containing aromatic resins using a near-infrared spectrometer. And waste plastic containing an aliphatic resin are preferably used separately. Near-infrared spectroscopy is an electromagnetic wave having a wavelength of 720 to 2500 nm. When this is irradiated onto the surface of resin waste, a specific wavelength is absorbed, transmitted, or reflected depending on the type of resin waste. The above fractionation can be performed easily and non-destructively using the spectrum obtained in (1). Of course, when waste plastics containing aromatic resins and waste plastics containing aliphatic resins are not mixed and are brought into a cement factory, it can be easily managed by installing and managing a separate place. The use according to the kind becomes possible.

  Next, as an example of a method for using resin waste according to the present invention, a waste plastic containing an aromatic resin is 3 mm to 20 mm, 20 mm or more, and a waste plastic containing an aliphatic resin is 5 mm in a cement manufacturing factory. After adjusting the particle size to 50 mm or less and 50 mm or more, the waste plastic containing the aromatic resin is weighed with an auto feeder from the burner 4a in front of the kiln, and blown at 2 t / h with a roots blower. It measured to the kiln bottom part 14 with the auto feeder, and it injected | thrown-in at 2 t / h from the exclusive duct. On the other hand, a mixed waste plastic containing both aromatic resin and aliphatic resin, adjusted to 3 mm or more and 20 mm or less and 20 mm or more, is weighed with an auto feeder from the burner 4a in front of the kiln, and blown at 2 t / h with a roots blower. A waste plastic containing an aliphatic resin, the particle size of which was adjusted to 5 mm or more and 50 mm or less and 50 mm or more, was weighed into the kiln bottom part 14 by an auto feeder, and charged at 2 t / h from a dedicated duct. At each level, the DXNs concentration in the exhaust gas was measured at the outlet of the main exhaust wind turbine 6 of the cement baking apparatus 1 24 hours after the start of charging. In addition, the color tone (b value) of the cement clinker sampled at the time of introduction of each level was measured and compared with the normal control value (6.5). The DXNs in the exhaust gas was measured by a measuring method based on JIS-K-0311, and the color tone was measured by a spectral colorimetric method based on JIS-Z-8722.

  As described above, waste plastic containing aromatic resin is blown from the kiln burner 4a of the cement kiln, and waste plastic containing aliphatic resin is introduced into the kiln bottom 14 (or calcining furnace 3). It can be seen that the amount of DXNs produced in the combustion exhaust gas of the cement firing apparatus 1 is reduced compared to the conventional case where the use position is not selected depending on the type of resin, and the cement clinker prevents landing combustion by adjusting the particle size to be small. It was found that there was no adverse effect on the color tone and the amount of DXNs produced was reduced.

DESCRIPTION OF SYMBOLS 1 Cement baking apparatus 2 Preheater 2a Lowermost cyclone 2b 3rd stage cyclone 2c 2nd stage cyclone 2d Uppermost stage cyclone 3 Calciner 4 Cement kiln 4a Kiln front burner 5 Clinker cooler 6 Main exhaust windmill 7-11 Raw material chute 12 Cooler extraction Duct 13 Rising duct 14 Kiln bottom 15 Kiln front

Claims (5)

  Waste plastic containing 50 mass% or more of aromatic resin is blown from the burner in front of the kiln of the cement kiln, and waste plastic containing 90 mass% or more of aliphatic resin is introduced into the kiln bottom of the cement kiln or / and calcining furnace. A method for using resinous waste characterized by the above.   The received resin waste is separated into waste plastic containing aromatic resin and waste plastic containing aliphatic resin, and the waste plastic containing 50% by mass or more of the separated aromatic resin is placed in front of the kiln of the cement kiln. A method of using resinous waste, characterized in that waste plastic containing 90% by mass or more of an aliphatic resin blown and sorted from a burner is placed in a kiln bottom of a cement kiln or / and a calcining furnace.   The method for using resinous waste according to claim 2, wherein the waste plastic containing the aromatic resin and the waste plastic containing the aliphatic resin are separated using near-infrared spectroscopy. .   Resin according to claim 1, 2 or 3, characterized in that waste plastic containing 50% by mass or more of the aromatic resin is crushed, particle size is adjusted to 3 mm or more and 20 mm or less and blown from a burner in front of a kiln of a cement kiln. To use municipal waste.   The waste plastic containing 90% by mass or more of the aliphatic resin is crushed, adjusted to a particle size of 5 mm or more and 50 mm or less, and charged into a kiln bottom of a cement kiln or / and a calcining furnace. A method of using the resin waste according to 2 or 3.

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