JP2010167369A - System and method for drying water-containing organic waste - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively dry a water-containing organic waste without a bad influence on cement manufacturing. <P>SOLUTION: The system 1 for drying the water-containing organic waste includes a probe 5 for extracting a part of combustion gas from a kiln exhaust gas passage extending from the chimney part of a cement kiln 4 to a final cyclone in order to remove chlorine, a high-temperature bag filter 8 for solid-gas separation of the extracted gas at temperatures ranging from 300 to 700°C which has been extracted by the probe 5 and for recovering a dust D2 containing the chlorine, a superheated steam generator 13 for heating steam using an exhaust gas G3 from the high-temperature bag filter 8 to produce superheated steam S, and a crushing air flow dryer 14 for drying and crushing the water-containing organic waste W while bringing the water-containing organic waste W into direct contact with the superheated gas S supplied by the superheated steam generator 13. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a system and method for drying water-containing organic waste such as high water content organic sludge.

  With the spread of sewerage and the implementation of advanced wastewater treatment, the amount of sludge generated from sewage treatment facilities has been increasing year by year, and the treatment method has become a problem. Most of the sludge is disposed of by landfill, but the landfill site is tight and it is extremely difficult to secure a new disposal site.

  In recent years, in order to solve these problems, a method has been adopted in which sewage sludge such as sewage sludge is brought into a cement manufacturing plant for treatment. This method not only makes it unnecessary to secure a landfill site, but also can treat a large amount of sludge, and thus has attracted a great deal of attention.

  As one of the above-mentioned methods, for example, Patent Document 1 describes a treatment method in which water-containing sludge brought into a cement manufacturing factory is dried and used as a fuel for cement firing. In this processing method, as shown in FIG. 2, the heat exchanger 31 performs heat exchange between the exhaust gas separated from the second cyclone 32b of the preheater 32 and the superheated steam, and dries the high-temperature superheated steam after the heat exchange. A step of introducing into the machine 33, drying the hydrous sludge to dry sludge, heat-exchanging the superheated steam after drying again in the heat exchanger 32, and recycling the sludge for drying, and the obtained drying And supplying the sludge as a fuel to the calciner 34 and burning it.

JP 2008-114173 A

  In the treatment method described in Patent Document 1, the water-containing sludge is efficiently dried by drying the water-containing sludge with a high-temperature superheated steam. However, when the superheated steam is generated, the preheater 32 is extracted. Since the steam is heated using the exhaust gas, the thermal efficiency in the raw material preheating process is lowered, and there is a risk of insufficient preheating of the cement raw material.

  Further, in the cement manufacturing facility, there is a case where a waste heat power generation facility that generates power using the exhaust gas of the preheater 32 is provided, but when the exhaust gas is separated from the preheater 32 for heating the steam as in the above-described processing method. Moreover, there is a possibility that the power generation amount on the power generation facility side is reduced.

  Accordingly, the present invention has been made in view of the problems in the conventional technology described above, and provides a drying system and the like that can efficiently dry water-containing organic waste without adversely affecting cement production. The purpose is to do.

  In order to achieve the above-mentioned object, the present invention is a water-containing organic waste drying system for extracting a part of combustion gas from a kiln exhaust gas flow path from a kiln bottom of a cement kiln to a lowermost cyclone. A high-temperature solid-gas separation device that separates solid gas from the extraction gas extracted by the extraction device at a temperature of 300 ° C. to 700 ° C. and collects dust containing chlorine, and an exhaust gas from the high-temperature solid-gas separation device. The apparatus includes a superheated steam generator that uses the heated superheated steam to generate superheated steam, and a dryer that dries the hydrated organic waste with the superheated steam supplied from the superheated steam generator.

  And according to this invention, since a water-containing organic waste is dried using chlorine bypass exhaust, it becomes possible to dry a water-containing organic waste, without having a bad influence on cement manufacture. Further, since the superheated steam is used for drying the water-containing organic waste, it can be efficiently dried. Furthermore, since a high-temperature solid-gas separation device is installed so that high-temperature exhaust gas can be obtained and the exhaust gas is used for heating steam in the superheated steam generator, superheated steam can be generated efficiently. In addition, the generation of dioxins can be suppressed by solid-gas separation of the extracted gas using a high-temperature solid-gas separation device.

  In the water-containing organic waste drying system, the dryer is crushed air-flow drying for crushing and drying the water-containing organic waste while bringing the superheated steam supplied from the superheated steam generator into direct contact with the water-containing organic waste. Can be a machine. According to this, it is possible to efficiently dry the hydrous organic waste while greatly increasing the contact area between the hydrous organic waste and the superheated steam. Therefore, it is possible to reduce the size of the dryer, and it is possible to keep the apparatus and operation costs low.

  The water-containing organic waste drying system may include a circulation route for returning the steam discharged from the dryer to the superheated steam generator. As a result, the steam whose temperature has been reduced by the dryer can be introduced into the superheated steam generator and reheated.

  The water-containing organic waste drying system may include a discharge unit that discharges excess steam from the circulation route, and unnecessary steam can be discharged out of the system.

  In the water-containing organic waste drying system, the high-temperature solid-gas separation device may be a solid-gas separation device including a ceramic filter. According to this, even if the extraction gas extracted by the extraction device is allowed to flow as it is, the high-temperature exhaust gas can be appropriately obtained without causing a failure of the solid-gas separation device.

  In the water-containing organic waste drying system, the high-temperature solid-gas separation device includes a classifier for separating coarse powder from the extracted gas extracted by the extraction device, and the extracted gas containing fine powder discharged from the classifier Can be supplied to.

  Further, the present invention is a method for drying a water-containing organic waste, wherein a part of combustion gas is extracted from a kiln exhaust gas passage from a kiln bottom of a cement kiln to a lowermost cyclone, and the extracted gas extracted is Solid-gas separation is performed at a temperature of 300 ° C. or higher and 700 ° C. or lower to recover dust containing chlorine, steam is heated using the exhaust gas after the dust is recovered, and superheated steam is generated. The water-containing organic waste is dried.

  According to the present invention, the water-containing organic waste can be efficiently dried in addition to drying the water-containing organic waste without adversely affecting the cement production, as in the case of the above invention. Furthermore, superheated steam can be efficiently generated, and at the same time, generation of dioxins can be suppressed.

  As described above, according to the present invention, it is possible to efficiently dry water-containing organic waste without adversely affecting cement production.

It is a block diagram which shows one Embodiment of the drying system concerning this invention. It is a block diagram which shows the processing equipment of the conventional water-containing organic sludge.

  Next, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows an embodiment of a water-containing organic waste drying system according to the present invention. The drying system 1 is roughly divided from a kiln bottom of a cement kiln 4 to a lowermost cyclone (not shown) of a preheater. From the kiln exhaust gas flow path, the chlorine bypass facility 2 that extracts a portion of the combustion gas and removes chlorine, and drying to dry water-containing organic waste such as water-containing organic sludge (hereinafter referred to as “waste” as appropriate) The facility 3 is configured.

  The chlorine bypass facility 2 includes an extraction probe 5 for extracting a part of the combustion gas from the kiln exhaust gas passage, a cooling fan 6 for supplying cold air to the probe 5, and coarse powder contained in the extraction gas G1 extracted by the probe 5. Cyclone 7 as a classifier for separating D1, high-temperature bag filter 8 for solid-gas separation of exhaust gas G2 containing fine powder D2 discharged from cyclone 7, and fine powder (chlorine bypass dust) collected by high-temperature bag filter 8 Are comprised of a dust tank 9 that collects the exhaust gas and an exhaust fan 10 that attracts the exhaust gas G3 of the high-temperature bag filter 8.

  Of the above configuration, the high-temperature bag filter 8 is, for example, a bag filter including a ceramic filter, and is a high heat-resistant solid-gas separation device having heat resistance up to about 900 ° C. Various types of bug filters have been developed, such as those in which a plurality of rod-shaped ceramic tubes (ceramic filters) formed into honeycomb cells are arranged, and those using sheet-like ceramic filters. The type of filter is not particularly limited as long as fine particles of 0.1 μm or more can be collected from the inside.

  In general, the temperature of the extraction gas G1 immediately after extraction from the probe 5 is 300 to 700 ° C., and therefore the high-temperature bag filter 8 does not necessarily have heat resistance up to 900 ° C. The temperature of the extraction gas G1 It is enough if it has heat resistance that can withstand.

  On the other hand, the drying facility 3 includes a waste storage tank 12 for storing water-containing organic waste (hereinafter referred to as “waste” as appropriate) W such as water-containing organic sludge, a superheated steam generator 13 for generating superheated steam S, While the waste W and the superheated steam S are in direct contact with each other, the crushing air dryer 14 that crushes and drys the waste W, the supply device 15 that supplies the waste W to the crushing air dryer 14, and the superheated steam S is crushed. A blower 16 to be supplied to the air dryer 14, a cyclone 17 that separates the exhaust gas from the crushed air dryer 14, a bag filter 18 that collects dust contained in the steam discharged from the cyclone 17, the cyclone 17 and the bug The dry waste storage tank 19 for storing the dry organic waste W ′ recovered from the filter 18 and the superheated steam S ′ discharged from the crushing air dryer 14 are passed through the circulation duct 20. A circulation blower 21 back to the steam generator 13, and the surplus steam discharge portion 22 or the like for discharging the excess steam S ".

  The waste storage tank 12 is provided for storing the received waste W. The waste W may be a high water content organic sludge containing water of 40% by mass or more, and may be papermaking sludge, sewage sludge, bill pit sludge, food sludge and the like. A supply device 15 such as a screw feeder for supplying the waste W to the crushing air dryer 14 is attached to the waste storage tank 12 at the bottom.

  The superheated steam generator 13 is provided to generate the superheated steam S, and generates heat from the exhaust gas G3 from the chlorine bypass facility 2 and the steam flowing in the superheated steam generator 13 to generate the superheated steam S. In this superheated steam generator 13, a pipe for circulating the steam and a pipe for circulating the exhaust gas G3 from the chlorine bypass facility 2 are provided separately, and the steam and the exhaust gas G3 are not in direct contact with each other. Heat the steam (indirect heating). As the superheated steam generator 13, for example, a waste heat boiler, various heat exchangers capable of exchanging heat between gases, and the like can be used.

  The crushing air dryer 14 is provided to dry the waste W with the superheated steam S supplied from the superheated steam generator 13 through the blower 16 while crushing the waste W. This crushing air dryer 14 is a chain blow type dryer, and is provided with a supply port for waste W at the top and a supply port for superheated steam S from the superheated steam generator 13 at the bottom. And superheated steam S are brought into contact with each other in countercurrent. In addition, a rotation shaft 14a and a striking chain 14b that is fixed to the rotation shaft 14a, extends in the horizontal direction by centrifugal force and rotates with the rotation of the rotation shaft 14a, and crushes the waste W are provided inside.

  It should be noted that, instead of the chain blow type crushing air dryer 14, a rod hitting type, cage mill type or swivel type dryer in which round bars or the like are horizontally attached instead of the chain can be used. A cage mill type crushing air dryer is a drier equipped with crushing cages that are reversed to each other, and a swirling crushing air dryer is a crushing air dryer using a swirling air current.

  The cyclone 17 is provided for recovering the dry organic waste W ′ obtained by the crushing drying in the crushing air dryer 14, and the bag filter 18 is provided for recovering the dust in the exhaust gas of the cyclone 17. .

  The surplus steam discharge unit 22 is provided to discharge the surplus steam S ″ from the drying equipment 3, and the deodorizing process is performed on the surplus steam S ″ discharged from the surplus steam discharge unit 22 at the subsequent stage of the surplus steam discharge unit 22. A combustion furnace or the like (not shown) is disposed.

  Next, operation | movement of the drying system 1 which has the said structure is demonstrated, referring FIG.

  First, in the chlorine bypass facility 2, a part of the combustion gas is extracted by the probe 5 from the kiln exhaust gas passage from the kiln bottom of the cement kiln 4 to the lowermost cyclone, and at the same time, the cold air from the cooling fan 6 Rapid cooling to 700 ° C. or lower, which is the melting point of the compound. Next, in the cyclone 7, the extracted gas G1 exhausted from the probe 5 is separated into the coarse powder D1 and the exhaust gas G2 containing the fine powder D2, and the coarse powder D1 is returned to the cement kiln system.

  On the other hand, in the high temperature bag filter 8, the fine powder D2 in the exhaust gas G2 is collected and collected in the dust tank 9, and the exhaust fan 10 attracts the exhaust gas G3 of the high temperature bag filter 8 to overheat the drying equipment 3. It introduces into the steam generator 13. Since the high temperature bag filter 8 has heat resistance up to 900 ° C., the exhaust gas G2 supplied from the cyclone 7 can be solid-gas separated at the same temperature without cooling. G3 can be obtained.

  In addition, the extraction gas G1 from the kiln exhaust gas flow path may contain residual organic pollutants (POPs) such as dioxins (PCDD, PCDF, co-PCB). Thus, the generation of dioxins can also be suppressed.

  That is, dioxins have the property of being recombined when exposed to a temperature range of about 300 ° C., even if they are completely burned at a high temperature of 800 ° C. or higher and thermally decomposed. Since it functions as a catalyst for the resynthesis reaction, when the exhaust gas G2 of the cyclone 7 is cooled and solid-gas separated, resynthesis of dioxins thermally decomposed by the cement kiln 4 may be promoted. On the other hand, when the high temperature bag filter 8 is used, the exhaust gas G2 can be solid-gas separated while maintaining the temperature when discharged from the cyclone 7, so the fine powder D2 is removed by the high temperature bag filter 8. In the meantime, the temperature condition above the resynthesis temperature of dioxins can be maintained. For this reason, resynthesis of dioxins can be suppressed, and generation of organic pollutants can be suppressed.

  When the exhaust gas G3 from the high temperature bag filter 8 is supplied to the superheated steam generator 13 of the drying facility 3, the superheated steam generator 13 indirectly heats the steam using the exhaust gas G3 of the high temperature bag filter 8. , About 230 to 500 ° C., preferably about 250 to 400 ° C. is generated. At this time, exhaust gas G3 ′ after heat exchange with steam is generated, but this exhaust gas G3 ′ is generated in a state where it does not come into contact with steam, so even if harmful substances are mixed in the steam, exhaust gas G3 ′ is generated. G3 ′ is not contaminated. Therefore, the exhaust gas G3 'can be returned to the cement kiln system as it is or used in other cement manufacturing processes.

  Next, the waste W from the waste storage tank 12 is supplied to the upper part of the crushing air dryer 14 via the supply device 15, and the superheated steam from the superheated steam generator 13 is supplied from the lower part of the crushing air dryer 14. S is introduced through the blower 16. Since the temperature of the superheated steam S is about 230 to 500 ° C., the retained heat amount per unit volume is large, and the heat amount is sufficient to dry the waste W.

  In the crushing air dryer 14, the waste W and the superheated steam S are in direct contact with each other and are dried while crushing the waste W by the striking chain 14b provided inside the crushing air dryer 14. . Thereby, it can dry from the surface, increasing the specific surface area of the waste W. As a result, in addition to improving the drying efficiency by increasing the specific surface area, the crushing efficiency is also improved by the surface drying of the waste W, and the overall drying efficiency can be drastically improved compared to the conventional case. It becomes possible. Moreover, since the superheated steam S not containing oxygen is used, there is no possibility of explosion of the crushed air dryer 14 or the like.

  Here, when the outlet gas temperature of the crushing air dryer 14 is too high, such as when the supply amount of the waste W to the crushing air dryer 14 is temporarily reduced, the front stage of the crushing air dryer 14 The cooling air C can be introduced.

  Next, the dried organic waste W ′ crushed and dried by the crushing air dryer 14 is collected by the cyclone 17 and the bag filter 18, and the collected dried organic waste W ′ is stored in the dried waste storage tank 19. It can be used as fuel for cement firing equipment. Further, the recovered dry organic waste W ′ can be transported to a device or the like different from the cement baking device via a blower (not shown). Further, the recovered dried organic waste W 'and raw sludge can be introduced into a kneader to form a granular material, and then used as a fuel.

  On the other hand, the dried superheated steam S ′ discharged from the crushing air dryer 14 is returned to the superheated steam generator 13 through the circulation duct 20 by the circulation blower 21. As a result, the steam whose temperature has been reduced by the crushed air dryer 14 is introduced into the superheated steam generator 13 and reheated.

  The surplus steam S ″ staying in the drying facility 3 can be appropriately discharged to the outside via the surplus steam discharge unit 22 and heated in a combustion furnace or the like (not shown) to perform the deodorization process. "" Can also be discharged into sewage after condensation without heating in a combustion furnace or the like.

  As described above, according to the present embodiment, since the waste W is dried using the chlorine bypass exhaust, the waste W can be dried without adversely affecting cement production. That is, the chlorine bypass facility 2 is a facility that has been installed for the purpose of removing chlorine, and in this embodiment, the waste W is dried using the exhaust gas G3, so that a new one is used from the cement firing facility. The combustion gas is not extracted. For this reason, the cement kiln 4 and the preheater are not accompanied by deterioration of thermal efficiency, and even when a waste heat power generation facility (not shown) is provided, the power generation amount is not reduced.

  Moreover, in the drying equipment 3, since the waste W is dried using the superheated steam S, the waste W can be efficiently dried. Furthermore, in the chlorine bypass facility 2, the high-temperature bag filter 8 is installed so that the high-temperature exhaust gas G3 can be obtained, and the exhaust gas G3 is used for heating the steam in the superheated steam generator 13. Can be generated. In particular, the amount of combustion gas extracted from the chlorine bypass facility 2 is relatively small, about 3 to 10% of the combustion gas flowing through the kiln exhaust gas passage from the bottom of the kiln 4 to the bottom cyclone. Since the temperature of the exhaust gas G3 of the high-temperature bag filter 8 is high, the steam can be appropriately heated even with a small amount of the exhaust gas G3.

  In the above embodiment, after the coarse powder D1 is classified by the cyclone 7, the exhaust gas G2 containing the fine powder D2 is introduced into the high-temperature bag filter 8, but the extracted gas extracted by the probe 5 without providing the cyclone 7. G1 may be directly introduced into the high-temperature bag filter 8.

  Further, the cyclone 17 on the drying equipment 3 side is not limited to one stage as shown in the figure, and can be multistage. In that case, in order to collect finer dust in the latter stage, Usually, the cyclone diameter is made smaller as the cyclone. However, in such a configuration, there is a possibility that a sufficient air volume may not be ensured, so a multi-cyclone can be employed. Furthermore, if the dust concentration of the fine dust at the outlet of the cyclone 17 is low enough not to adversely affect the drying system 1, the bag filter 18 can be omitted. If excess steam S ″ is discharged, a bag filter is required downstream of the excess steam discharge portion 22.

DESCRIPTION OF SYMBOLS 1 Drying system of water-containing organic waste 2 Chlorine bypass equipment 3 Drying equipment 4 Cement kiln 5 Probe 6 Cooling fan 7 Cyclone 8 High temperature bag filter 9 Dust tank 10 Exhaust fan 12 Waste storage tank 13 Superheated steam generator 14 Crushing air dryer 14a Rotating shaft 14b Strike chain 15 Supply device 16 Blower 17 Cyclone 18 Bag filter 19 Dry waste storage tank 20 Circulation duct 21 Circulation blower 22 Surplus steam discharge part

Claims (7)

An extraction device for extracting a part of the combustion gas from the kiln exhaust gas passage from the bottom of the kiln of the cement kiln to the lowermost cyclone;
A high-temperature solid-gas separation device that separates the gas extracted by the extraction device at a temperature of 300 ° C. or higher and 700 ° C. or lower and collects dust containing chlorine;
A superheated steam generator for generating superheated steam by heating steam using the exhaust gas of the high-temperature solid-gas separator;
A drying system for hydrous organic waste, comprising: a dryer for drying hydrous organic waste by superheated steam supplied from the superheated steam generator.   The dryer is a crushing air dryer that crushes and drys the hydrous organic waste while directly contacting the superheated steam supplied from the superheated steam generator with the hydrous organic waste. 2. The water-containing organic waste drying system according to 1.   The water-containing organic waste drying system according to claim 1, further comprising a circulation route for returning the steam discharged from the dryer to the superheated steam generator.   The water-containing organic waste drying system according to claim 3, further comprising a discharge unit that discharges surplus steam from the circulation route.   5. The water-containing organic waste drying system according to claim 1, wherein the high-temperature solid-gas separation device is a solid-gas separation device including a ceramic filter. Comprising a classifier for separating coarse powder from the extraction gas extracted by the extraction device;
6. The water-containing organic waste drying system according to any one of claims 1 to 5, wherein an extraction gas containing fine powder discharged from the classifier is supplied to the high-temperature solid-gas separation device. A part of the combustion gas is extracted from the kiln exhaust gas passage from the bottom of the kiln of the cement kiln to the bottom cyclone,
The extracted gas extracted is solid-gas separated at a temperature of 300 ° C. or higher and 700 ° C. or lower to recover dust containing chlorine,
Heating the steam using the exhaust gas after collecting the dust, generating superheated steam,
A method for drying water-containing organic waste, comprising drying the water-containing organic waste with the generated superheated steam.

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