JP4153411B2 - Firing system for papermaking sludge waste - Google Patents

Description

  The present invention relates to a firing system for firing this papermaking sludge waste when recovering inorganic materials such as calcium carbonate from the papermaking sludge waste discharged in the papermaking process.

  In the papermaking industry, papermaking sludge waste (also called papermaking sludge) is generated mainly in the papermaking process using wastepaper as a raw material. This papermaking sludge waste includes organic materials such as fiber materials, adhesives, printing inks, and white inorganic materials such as calcium carbonate, kaolin, and metakaolin. If a white inorganic material can be recovered from this papermaking sludge waste, it can be reused as a papermaking material such as an internal filler and a coating pigment.

  As a means for recovering a white inorganic material, particularly calcium carbonate, from papermaking sludge waste, a technique is known in which the papermaking sludge waste is dried, carbonized and fired, and the inorganic material is recovered as a fired product. In this way, by firing paper sludge waste, attempts have been made to produce a fired product with high whiteness and reuse it as a papermaking raw material.

  However, the currently proposed method for recovering calcium carbonate has a complicated structure, a high equipment cost and a running cost, and has problems such as decomposition of calcium carbonate. Therefore, a papermaking sludge waste firing system that can be put into practical use has not been established yet.

For example, the present applicant has proposed a recovery method for obtaining predetermined calcium carbonate (baked product) by drying and carbonizing paper sludge waste, followed by primary firing and then secondary firing (patent application). 2003-53508). This recovery method is for firing paper sludge waste in an oxidizing atmosphere containing CO ₂ (carbon dioxide) having a partial pressure of about 5 to 30% in addition to oxygen. Such an atmosphere containing CO ₂ suppresses decomposition of calcium carbonate into calcium oxide, and an inorganic material having high whiteness (whiteness of 80% or more) can be recovered.

  Moreover, in this collection method, the vapor | steam and dry distillation gas which generate | occur | produce in a drying apparatus and a carbonization apparatus are detoxified in a smoke-extinguishing chamber. By using this detoxified gas as a heating gas for drying or carbonization, heat energy is effectively utilized.

However, according to the proposed method described above, (1) two calcining apparatuses for calcining the paper sludge waste after carbonization are necessary for primary calcining and secondary calcining, and drying is performed. Equipment is also required for carbonization and carbonization, resulting in high equipment costs. Further, (2) for using the number of CO ₂ gas in firing, it takes running cost for ensuring the CO _2. (3) Even if the heat energy of the gas detoxified in the smoke evacuation chamber is used for drying and carbonization heating, the heat of the relatively high-temperature gas after being used as the heating gas is further used. To do this, equipment costs and running costs are required.

  Then, an object of this invention is to provide the baking system of papermaking sludge waste material which can reduce an installation cost and a running cost.

  The baking system of the present invention that solves the above-mentioned problems is a pre-drying device for heating papermaking sludge waste to be treated to evaporate water, sucking steam generated from the pre-drying device, and Separation device for separating a part, drying carbonization device for drying and carbonizing the papermaking sludge waste having reduced water content in the preliminary drying device, and papermaking sludge disposal carbonized in the drying carbonization device A firing device for firing an object, and a smoke eliminator for burning and detoxifying the generated gas generated in at least one of the dry carbonization device and the firing device, and harmless in the smoke eliminator The gas is used to heat the calcining device, then used to heat the drying carbonization device, and further to heat the preliminary drying device Characterized in that it is needed.

  According to this invention, the papermaking sludge waste containing about 50 to 60% of water can be preliminarily dried to about 20 to 40% by the predrying device provided in the firing system. Therefore, a preliminary drying apparatus having a simple configuration capable of evaporating moisture (for example, the stirrer may be a simple paddle type and may be an apparatus that can be heated to a relatively low temperature of about 100 to 300 ° C.). Thus, in the downstream of the preliminary drying device, drying and carbonization are performed by one drying carbonization device, and firing is performed by one firing device, whereby an appropriate fired product can be obtained from the papermaking sludge waste. As a result, from the conventionally proposed firing system consisting of four devices, namely a drying device, a carbonizing device, a primary firing device and a secondary firing device, a firing comprising three devices: a preliminary drying device, a drying carbonization device and a firing device. By setting it as a system, an installation can be simplified and an installation cost can be reduced.

  Moreover, the vapor | steam in the predrying apparatus discharged | emitted from this baking system does not contain tar which arises in carbonization processing. As a result, with respect to the steam in the preliminary drying device, the water separated by the separation device can be easily subjected to water treatment, and the equipment cost for the water treatment does not increase greatly.

  Furthermore, since the moisture in the paper sludge waste is reduced by the pre-drying device, when the gas generated from the paper sludge waste in the drying carbonization device and the calcining device is burned in the smoke eliminator and made harmless, The energy for heating can be reduced.

  Furthermore, the thermal energy can be effectively used by sequentially using the high-temperature gas burned in the smoke eliminator for heating the calcining device, the drying carbonization device, and the preliminary drying device. In particular, by using a gas of about 400 ° C. used for heating in the drying carbonization apparatus in the preliminary drying apparatus, the thermal energy can be used more effectively than in the prior art. As a result, the heating device and auxiliary fuel used for heating each device become unnecessary, or a small-scale heating device and a small auxiliary fuel may be used. Can be reduced.

  In the firing system of the present invention, the separating device sends a gas from which a part of moisture has been separated to the smoke eliminating device.

  According to this invention, by sending a gas (gas) from which a part of moisture has been separated from the vapor in the preliminary drying device to the smoke eliminator, this gas can also be made non-brominated and harmless in the smoke eliminator. . Therefore, in a smoke eliminator for detoxifying the generated gas in a dry carbonization apparatus or a baking apparatus, the exhaust gas in the preliminary drying apparatus can be treated together, so it is necessary to provide an additional apparatus for this exhaust gas treatment. There is no significant increase in equipment costs.

  In addition, since a part of the moisture of the steam generated in the preliminary drying device is removed by the separation device, the energy for heating the water vapor is large when the gas sent from the separation device is burned in the smoke eliminator. There is no increase.

  Further, the exhaust gas in this firing system can be only the gas used for heating the pre-drying device and the like, and the exhaust gas treatment can be performed easily, thereby reducing the equipment cost for the exhaust gas treatment. be able to.

In the calcination system of the present invention, the gas that has been rendered harmless in the smoke eliminator and used for heating in the calcination apparatus and the dry carbonization apparatus is introduced with outside air, and the partial pressure of CO ₂ is 5 to 30%. And the oxygen concentration is increased and is used for firing the paper sludge waste in the firing apparatus.

According to this invention, the gas containing CO ₂ generated from papermaking sludge waste in the drying carbonization apparatus and the baking apparatus, which are in the system of the baking system, is burned by the smoke eliminator and heated the baking apparatus and the dry carbonization apparatus. Later, a part will flow into the firing apparatus. Therefore, by introducing this CO ₂ into the baking apparatus, the calcium carbonate in the papermaking sludge waste is hardly decomposed into calcium oxide, and an appropriate baking product can be obtained. As a result, the amount of CO ₂ introduced from the outside of the firing system is reduced or no longer required, the CO ₂ basic unit is reduced, and the running cost required for supplying CO ₂ is reduced. Or since it becomes unnecessary, the running cost as the whole system can be reduced.

In addition, by introducing outside air into the generated gas in the firing system system, the partial pressure of the CO ₂ gas can be controlled within the above-mentioned range, and the gas with an increased oxygen concentration can be used for the paper sludge waste in the firing device. It can be used for baking. Therefore, by providing a simple facility for introducing the outside air, the firing process in the firing apparatus can be efficiently advanced without incurring a large facility cost or running cost.

According to the paper sludge waste firing system of the present invention, the number of devices constituting the system can be reduced, and the equipment cost can be reduced. In addition, since moisture is reduced by the pre-drying device, there is little water vapor in the gas generated from the paper sludge waste in the dry carbonization device and baking device, and energy for heating the water vapor in the smoke eliminator is reduced. Can do. Furthermore, since CO ₂ used for firing can be generated in the system of the firing system, the running cost for securing CO ₂ can be reduced. Furthermore, the heat energy of the gas detoxified in the smoke eliminator can be used for heating at each stage of calcination, dry carbonization, and preliminary drying, and the running cost for heating at each stage can be reduced. it can. As described above, according to the present invention, it is possible to provide a system capable of reducing the facility cost and the running cost when baking paper sludge waste.

  The firing system of the present invention will be specifically described below with reference to the drawings.

  FIG. 1 is a schematic view showing an example of a firing system of the present invention.

  As shown in FIG. 1, the baking system 100 of the present invention sucks steam generated from the preliminary drying device 10 for heating the paper sludge waste X to be treated and evaporating the moisture. In the separation device 20 for separating a part of the moisture from the steam, the dry carbonization device 30 for drying and carbonizing the papermaking sludge waste X whose moisture has been reduced in the preliminary drying device 10, and the drying carbonization device 30 A calciner 40 for calcining the carbonized paper sludge waste X, and a smoke eliminator 50 for burning and detoxifying the gas generated in at least one of the dry carbonizer 30 and the calciner 40; . Further, the detoxified gas in the smoke eliminator 50 is used to heat the baking apparatus 40, then used to heat the dry carbonization apparatus 30, and further used to heat the preliminary drying apparatus 10. . In FIG. 1, the flow of the papermaking sludge waste X and the moisture W is indicated by solid lines, and the flow of gas (generated gas or the like) is indicated by broken lines. Below, each apparatus etc. which comprise the baking system 100 are demonstrated.

  First, the papermaking sludge waste X to be processed will be described.

  In the present embodiment, papermaking sludge waste X generated mainly in a papermaking process using wastepaper as a raw material is a processing target. This paper sludge waste X contains about 50 to 60% of water even after the water is squeezed out by a so-called screw press or the like.

  Next, the preliminary drying apparatus 10 will be described.

  The preliminary drying device 10 heats the papermaking sludge waste X to be processed to evaporate the water. Specifically, the preliminary drying apparatus 10 is provided on the outer periphery in order to heat, for example, the preliminary drying chamber 11 that heats the paper sludge waste X and conveys the moisture while evaporating the papermaking sludge waste X. A heating chamber 12.

  The preliminary drying chamber 11 is provided with a stirring member (not shown) so that the papermaking sludge waste X can be efficiently heated. Although the kind of this stirring member is not specifically limited, For example, the paddle type stirring member 13 as shown in FIG. 2 is provided.

  This paddle type stirring member is provided with a plurality of thick sector disks 13B perpendicular to the central axis 13A, and each disk 13B is provided with stirring blades 13C. Further, the fan-shaped surface 13D of each disk 13B is a surface cut so as to send the papermaking sludge waste X downstream, and the surface 13E provided in parallel to the central axis 13A of each disk 13B is a papermaking sludge. The surface is cut to return the waste X to the upstream. The paddle type stirring member does not have to be provided with a mechanism for transporting the paper sludge waste X, and is pushed out when the paper sludge waste X is newly introduced into the preliminary drying chamber 11. The papermaking sludge waste X that has already been introduced to the vehicle will be transported.

  In the preliminary drying chamber 11, heating is performed to such an extent that tar is not generated from the papermaking sludge waste X. Specifically, the papermaking sludge waste X is heated to about 100 to 300 ° C. For this purpose, the gas used for heating in the dry carbonization apparatus 30 described later is introduced into the heating chamber 12. In this way, the thermal energy of the gas used for heating in the dry carbonization apparatus 30 can be used effectively.

  In addition, since the function of evaporating and reducing a part of the water content of the papermaking sludge waste X is important for the preliminary drying apparatus 10, the type of the apparatus is not limited to the above-described one. For example, the conventional rotary kiln type An apparatus using the heat transfer tube may be used.

  Further, the preliminary drying chamber 11 is connected to a separation device 20 described later, and the vapor generated from the papermaking sludge waste X is sucked into the separation device 20.

  As described above, the preliminary drying apparatus 10 introduces the papermaking sludge waste X from the introduction port 11A of the preliminary drying chamber 11, evaporates the moisture while stirring the papermaking sludge waste X, and discharges it from the discharge port 11B. The steam generated at this time is sucked into the separation device 20 from a steam discharge port 11C connected to the separation device 20 described later.

  In addition, the paper-making sludge waste X stirred while being heated in the preliminary drying chamber 11 has a water content of about 50 to 60% before being introduced into the preliminary drying chamber 11, but a water content of about 20 to 40%. And discharged.

  On the other hand, the pre-drying apparatus 10 introduces hot air from the hot air inlet 12A provided near the outlet 11B in the heating chamber 12 and uses it to heat the paper sludge waste X. Hot air is discharged from 12B. For example, as shown in FIG. 1, the hot air discharged from the preliminary drying apparatus 10 is sucked by the induction fan 62 and discharged from the exhaust pipe 63 after the dust collector 61 collects the dust.

  Thus, by providing the preliminary drying device 10 in the firing system 100, the paper sludge waste X can be appropriately dried. As described later, three units including the drying carbonization device 30 and the firing device 40 are provided. Thus, it is possible to obtain the fired product Z from the papermaking sludge waste X. Therefore, the facilities are simplified compared to the conventionally proposed firing system comprising four units of drying, carbonization, primary firing, and secondary firing.

  Moreover, by not drying the papermaking sludge waste X too much by the preliminary drying apparatus 10, dust, carbonization gas, and tar are not generated from the papermaking sludge waste X, and only moisture is discharged. This eliminates the need for a special water treatment facility for the water removed by the separation device, facilitates maintenance of the separation device, and does not significantly increase facility costs and running costs.

  Furthermore, the temperature of the gas discharged from the hot air outlet 12B in the heating chamber 12 of the preliminary drying apparatus 10 is lower than that of the gas discharged from the conventional drying apparatus, and heat is effectively used, and the environment is improved. Can be reduced.

  Next, the separation device 20 will be described.

  The separation device 20 sucks the steam generated from the preliminary drying device 10 and separates a part of the moisture from the steam. Specifically, the separation device 20 includes a condenser 21 and an exhaust fan 22 provided downstream thereof.

  The exhaust blower 22 sends the gas G from which the moisture W is separated in the condenser 21 to the smoke eliminator 50 described later. In this way, the gas sent into the smoke eliminator 50 is made non-brominated and harmless by the smoke eliminator 50.

  Next, the dry carbonization apparatus 30 will be described.

  The dry carbonization device 30 dries and carbonizes the papermaking sludge waste X whose moisture has been reduced in the preliminary drying device 10. Specifically, the dry carbonization apparatus 30 includes, for example, a dry carbonization chamber 31 that heats the papermaking sludge waste X to dry the moisture and conveys the carbonization while performing carbonization, and an outer periphery for heating the dry carbonization chamber 31. And a heating chamber 32 provided in.

  The dry carbonization chamber 31 is provided with a stirring and conveying member (not shown) so that the paper sludge waste X can be efficiently heated and conveyed. The stirring / conveying member has a function of stirring and conveying, and a screw or the like that allows gas to pass through the inside of the dry carbonization chamber 31 is preferably used.

  As this screw, the screw etc. which provided the ribbon-shaped ribbon screw member helically in the cage which consists of a several rod-shaped member proposed by the present applicant, for example are used.

  Such a screw as a stirring and conveying member is connected to the drive device 33 and is driven to rotate about an axis. The introduction port 31A for introducing the papermaking sludge waste X in the dry carbonization chamber 31 may be provided with an on-off valve T.

  In the dry carbonization chamber 31, the papermaking sludge waste X is dried and heated to such an extent that it can be carbonized. Specifically, the papermaking sludge waste X is heated at about 350 to 700 ° C. For this purpose, the gas used for heating in the baking apparatus 40 described later is introduced into the heating chamber 32. In this way, the thermal energy of the gas used for heating in the baking apparatus 40 can be used effectively. As shown in FIG. 1, the gas sent into the heating chamber 32 may be mixed with hot air generated in the auxiliary hot air generating furnace 64 to raise the gas temperature. The auxiliary hot air generating furnace 64 is provided with a burner B. The burner B burns auxiliary combustion fuel to generate hot air in the auxiliary hot air generating furnace 64.

  As described above, the drying carbonization apparatus 30 introduces the papermaking sludge waste X from the introduction port 31A of the drying carbonization chamber 31, evaporates the water while stirring the papermaking sludge waste X, and carbonizes it to discharge the discharge port 31B. To discharge from. The steam, dry distillation gas, and tar generated at this time are sent from the exhaust gas outlet 31C to the smoke eliminator 50 described later.

  On the other hand, the dry carbonization apparatus 30 introduces hot air from a hot air introduction port 32A of a heating chamber 32 provided near the above-described discharge port 31B and uses it to heat the paper sludge waste X, and then the hot air discharge port 32B. To discharge from.

  In addition, the hot air discharged | emitted from this dry carbonization apparatus 30 is sent to the heating chamber 12 of the preliminary drying apparatus 10 as mentioned above. Further, a part of the hot air is branched from that sent to the preliminary drying device 10 and sent into a firing chamber 41 of the firing device 40 described later.

  Next, the baking apparatus 40 will be described.

  The firing device 40 fires the papermaking sludge waste X carbonized in the dry carbonization device 30 to obtain a fired product Z. Specifically, the baking apparatus 40 includes, for example, a baking chamber 41 that conveys the papermaking sludge waste X while heating and baking, and a heating chamber 42 provided on the outer periphery to heat the baking chamber 41. It consists of.

  The baking chamber 41 is provided with a stirring and conveying member (not shown) so that the papermaking sludge waste X can be efficiently heated and conveyed. In addition, the present applicant has found that a fired product with high whiteness can be obtained by firing for a long time of 90 to 150 minutes, for example. Therefore, it is preferable that the firing chamber 41 includes a screw that can be stirred and transported over such a time. Such a screw is connected to the drive device 43 and rotates about an axis.

  In the firing chamber 41, the papermaking sludge waste X is heated to such an extent that it can be fired, and specifically, heated at about 650 to 800 ° C. For this purpose, a gas of about 800 ° C. that has been made non-brominated and harmless by the smoke eliminator 50 described later is introduced into the heating chamber 42. In this way, the thermal energy of the gas heated to a high temperature by the smoke eliminator 50 can be used effectively.

  Further, the firing gas generated in the firing chamber 41 is sent to a smoke eliminator 50 to be described later in order to make it non-brominated and harmless.

Moreover, a part of gas used for heating in the above-mentioned dry carbonization apparatus 30 is sent into the firing chamber 41. As described above, the gas used for heating in the dry carbonization apparatus 30 is mainly composed of the gas discharged in the dry carbonization chamber 31 and the firing chamber 41, and therefore contains a considerable amount of CO ₂ . . Therefore, by using this gas, the carbonized papermaking sludge waste X can be fired without decomposing calcium carbonate or the like. As shown in FIG. 1, this gas is mixed with outside air from the firing gas introduction port 65, and the partial pressure of CO ₂ becomes about 5 to 30%. The circulation blower 66 is used to enter the firing chamber from the introduction port 41 </ b> D. 41.

  From the above, the baking apparatus 40 introduces the papermaking sludge waste X from the introduction port 41A of the baking chamber 41, burns the papermaking sludge waste X while stirring, and discharges it as the fired product Z from the discharge port 41B. The firing gas generated at this time is sent from the exhaust gas outlet 41C to the smoke eliminator 50 described later.

  On the other hand, the baking apparatus 40 introduces hot air from the hot air introduction port 42A of the heating chamber 42 provided near the above-described discharge port 41B and uses it to heat the papermaking sludge waste X, and then from the hot air discharge port 42B. Discharge. In addition, the hot air discharged | emitted from this baking apparatus 40 is sent to the heating chamber 32 of the dry carbonization apparatus 30 as mentioned above.

  Finally, the smoke eliminator 50 will be described.

  In the smoke eliminator 50, the gas generated from the papermaking sludge waste X in the dry carbonization chamber 31 in the dry carbonization apparatus 30 and the gas generated from the papermaking sludge waste X in the baking chamber 41 in the baking apparatus 40 are introduced. In addition, the gas G separated from the capacitor 21 is introduced. Then, the smoke eliminator 50 burns the introduced gas using an auxiliary combustion fuel as necessary, at about 800 ° C. by the burner B, and renders it harmless. Thereafter, the smoke eliminator 50 sends the burned gas to the heating chamber 42 of the above-described baking apparatus 40, and this gas is used as a heat source for baking.

  In addition, the kind and system of the smoke eliminating apparatus 50 are not specifically limited, A conventionally well-known smoke eliminating apparatus can be used.

  As described above, by introducing the gas G from which the moisture W has been separated by the condenser 21 of the separation device 20, heat for heating the vapor in the smoke eliminator 50 becomes unnecessary, so the amount of fuel used for auxiliary combustion is reduced. Can be reduced.

  In addition, regarding the firing system 100 shown in FIG. 1, the processing temperature and the gas flow in each device are not limited to this, and further include other devices for processing the papermaking sludge waste X. You may go out.

  Moreover, the baking method demonstrated below is applicable to the baking system 100 of this invention. In addition, FIG. 3 is a flowchart which shows the flow of each process in the baking method of this papermaking sludge waste X.

  In this baking method, the papermaking sludge waste X to be treated is heated to evaporate moisture, and the steam generated in the preliminary drying process S1 is sucked, and the moisture W and the remaining gas G are sucked from the steam. A separation process S2 for separating the paper, a papermaking sludge waste X whose moisture has been reduced in the preliminary drying process S1, a drying carbonization process S3 for carbonization, and a papermaking sludge waste carbonized in the drying carbonization process S3. And a firing step S4 for firing X. This papermaking sludge waste X is obtained as a calcined product Z through the calcining step S4.

  Among these, the preliminary drying step S1 can be realized by the above-described preliminary drying device 10, and the separation step S2 can be realized by the above-described separation device 20. Further, the dry carbonization step S3 can be realized by the above-mentioned dry carbonization step, and the firing step S4 can be realized by the above-described firing device 40.

  As described above, the papermaking sludge waste X firing method can be realized by the papermaking sludge waste X firing system 100 of the present invention described above.

It is the schematic which shows an example of the baking system of this invention. It is a perspective view of the paddle with which the preliminary drying apparatus of the baking system shown in FIG. 1 is equipped. It is a flowchart which shows the flow of the baking method applied to the baking system of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Pre-drying device 11 ... Pre-drying chamber 12 ... Pre-drying heating chamber 13 ... Paddle used for pre-drying chamber 20 ... Separation device 21 ... Condenser 22 ... Exhaust blower 30 ... Drying carbonization device 31 ... Drying carbonization chamber 32 ... Drying Carbonization heating chamber 40 ... Baking device 41 ... Baking chamber 42 ... Baking heating chamber 50 ... Smoke eliminating device 100 ... Baking system X ... Paper sludge waste Z ... Baking product W ... Moisture G ... Gas

Claims (3)

A predrying device for heating the paper sludge waste to be treated to evaporate the water;
A separating device for sucking the steam generated from the preliminary drying device and separating a part of the moisture from the steam;
A drying carbonization device for drying and carbonizing the paper sludge waste having reduced moisture in the preliminary drying device;
A baking apparatus for baking the paper sludge waste carbonized in the dry carbonization apparatus;
A smoke eliminator for burning and detoxifying the generated gas generated in at least one of the dry carbonization device and the firing device,
The detoxified gas in the smoke eliminator is used to heat the calciner, then used to heat the dry carbonizer, and further used to heat the preliminary dryer. A characteristic paper baking sludge firing system.   The paper separator sludge firing system according to claim 1, wherein the separation device sends a gas from which a part of moisture has been separated to the smoke eliminating device. The gas detoxified in the smoke eliminator and used for heating in the calciner and the dry carbonizer is introduced with outside air, the partial pressure of CO ₂ is 5-30% and the oxygen concentration is increased, The papermaking sludge waste firing system according to claim 1 or 2, wherein the papermaking sludge waste is fired in the firing apparatus.

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