JP5403677B2 - Incineration main ash desalination system - Google Patents

Description

The present invention relates to desalting incineration main ash generated in an incinerator, such as municipal solid waste into the system for effectively utilized as a cement raw material.

  From incinerators such as municipal waste, incineration main ash from the hearth (hereinafter abbreviated as “main ash” as appropriate) and flue gas fly ash are generated. The main ash is landfilled as a general waste in a managed landfill. However, in recent years, since the remaining capacity of the final landfill site has decreased, various alternative processing methods have been studied and implemented.

  Fly ash with a high chlorine content and fine particle size is desalted by washing with water and used as a raw material for cement. On the other hand, the main ash having a low chlorine content and a coarse particle size has a low chlorine removal effect by washing with water compared to fly ash. Therefore, a large amount of water is required to obtain a sufficient removal rate as a desalting raw material. For this reason, a large amount of wastewater is generated, a large wastewater treatment facility is required, and it is difficult to perform desalting at a low cost.

  Therefore, in Patent Document 1, a plurality of mechanical wet classifiers of two or more stages are arranged in series, incineration ash is added to the former classifier, washing water is added to the latter classifier, and washing dehydration action Incinerated ash was moved counter-currently from the former stage to the latter stage and water was countercurrently moved from the latter stage to the former stage, and the coarse incinerated ash was taken out of the system from the latter stage and contained fine incinerated ash. A method is described in which the cleaning liquid is taken out from the previous stage, and then the cleaning liquid and fine particles are separated to obtain desalted incineration ash and a salt-containing cleaning liquid.

JP 2003-80199 A

  However, in the treatment method described in Patent Document 1, it is necessary to install two screw-type Akins classifiers, and in addition to the increase in equipment cost, moisture is required to sufficiently stir ash particles in a stirring tank. It is necessary to adjust the amount and adjust the viscosity to be suitable for agitation, so that the operation cost becomes high. As a result, it is difficult to reduce the main ash treatment cost.

  Therefore, in practice, the main ash is put into the cement kiln without being desalted, and the chlorine content is concentrated and discharged in the firing process, and is desalted. However, in this main ash treatment method, chlorine is volatilized by heating in the firing step, and the volatilized chlorine is discharged out of the system from the high-temperature part, so that the calorific intensity is deteriorated.

  Then, this invention is made | formed in view of the problem in the said prior art, Comprising: It aims at processing main ash at low cost, without causing deterioration of the calorific value basic unit in a cement baking process. .

To achieve the above object, the present invention includes a pit eluting the submerged baked却主ash salts, demineralized water containing the salts discharged from the pit, 200 ° C. discharged from the cement manufacturing facility Demineralization treatment of incinerated main ash comprising a concentrating device for concentrating with the following gas, a condensing device for condensing water vapor generated in the concentrating device, and a circulating device for returning condensed water generated in the condensing device to the pit The concentrator includes a preheating pipe in which an outer surface is in contact with the gas flow of 200 ° C. or less and the demineralized water flows therein, and an upstream side of the preheating pipe in the gas flow of 200 ° C. or less. And an evaporating and concentrating tube in which an outer surface is in contact with the gas flow of 200 ° C. or less and demineralized water preheated by the preheating tube flows therein.

And according to the present invention, the desalinated water of the incinerated main ash is concentrated by the concentrating device, and the condensed water obtained by condensing the water vapor generated by the concentration is circulated to reduce the size of the wastewater treatment facility for the desalted water. In addition, since the gas of 200 ° C. or less discharged from the cement production facility that has not been used for the concentration of demineralized water is used, the processing cost of the incinerated main ash can be greatly reduced. It does not cause deterioration of the caloric intensity. Also, with this configuration, the gas flow of 200 ° C. or less and the desalted waste water can be brought into countercurrent contact, and the desalted waste water can be efficiently concentrated by evaporation.

  In the above-described incineration main ash desalination system, the concentrating device can be disposed in the chimney upstream of the chimney that releases the cement kiln exhaust gas of the cement production facility to the atmosphere.

  As described above, according to the present invention, the wastewater treatment facility for incinerated main ash demineralized water is miniaturized, and exhaust gas from a cement production facility that has not been conventionally used is used to reduce the calorific value in the cement firing process. Incineration main ash can be processed at low cost without causing it.

It is a whole block diagram which shows the cement manufacturing equipment which installed the desalination processing system of the incineration main ash concerning this invention. It is a figure which shows the concentration apparatus of the desalination processing system of the incineration main ash concerning this invention, and its vicinity, Comprising: (a) is a top view, (b) is a front view. It is operation | movement explanatory drawing of the desalination processing system of the incineration main ash concerning this invention.

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

  FIG. 1 shows a cement production facility in which a desalination treatment system for incinerated main ash according to the present invention (hereinafter abbreviated as “demineralization treatment system”) is installed. This cement production facility 1 grinds cement raw materials. The raw material pulverizer 3, the preheater 7 for preheating the cement raw material R crushed by the raw material pulverizer 3, the calcining furnace 8 for calcining the preheated cement raw material R, and the calcined cement raw material R are fired. Cement kiln 9, clinker cooler 11 for cooling cement clinker obtained by firing, waste heat power generation facility 2 for generating power using sensible heat of combustion exhaust gas G1 discharged from preheater 7, and raw material crusher 3 is configured by a bag filter 4 for collecting the exhaust gas G2, a fan 5 for sucking the exhaust gas, a chimney 6 for discharging the exhaust gas G3 from the fan 5 to the atmosphere, and the like. Cal desalination system 21 is arranged in the flue 51 and the vicinity thereof between the fan 5 and the chimney 6.

  The desalination treatment system 21 uses the pit 22 for adding water W to the main ash A, submerging the main ash A to elute the salts, and the desalted water W1 discharged from the pit 22 using the exhaust gas G3 from the fan 5. The condensing device 23 for condensing the water vapor S generated by the concentrating device 23 and the condensing water 24 generated by the condensing device 24 are returned to the pit 22.

  As shown in FIG. 2, the concentrating device 23 evaporates by heating the demineralized water W <b> 1 from the pit 22 and the demineralized water W <b> 1 conveyed by the pump 31 by the exhaust gas G <b> 3 flowing in the flue 51. Therefore, the preheating pipe 32 and the evaporative concentration pipe 33 arranged in the flue 51, the first storage tank 34 storing the heated demineralized water W1, and the demineralized water W1 stored in the first storage tank 34 are evaporated and concentrated. The pump 35 transported to the pipe 33, the second storage tank 36 storing the concentrated water W2 concentrated in the evaporative concentration pipe 33, and the concentrated water W2 stored in the second storage tank 36 are transported to a wastewater treatment facility (not shown). It is composed of a pump 37 and the like.

  A plurality of preheating pipes 32 and evaporative concentrating pipes 33 are each extended in the vertical direction in the flue 51, and the preheating pipes 32 are arranged on the downstream side of the exhaust gas G3 flow and the evaporating and concentrating pipes 33 are arranged on the upstream side. The preheating pipe 32 and the evaporative concentration pipe 33 heat the demineralized water W1 supplied above each pipe by heat exchange without directly contacting the exhaust gas G3. The evaporating and concentrating tube 33 is configured to perform thin film flow distillation, and conveys the evaporated water vapor S to the condensing device 24 via the vapor conveying tube 38.

  The condensing device 24 is disposed on the downstream side of the concentrating device 23, and condenses the water vapor S by the vacuum pump 41 that sucks the water vapor S conveyed through the vapor conveying pipe 38 and the cooling water supplied to the condensing device 24. A pump (circulation device) 42 for returning the condensed water W4 generated in this way to the pit 22 is provided.

  Next, a method for desalting incinerated main ash using the desalination processing system 21 having the above-described configuration will be described. First, refer to FIG. 1 for the flow of the cement manufacturing facility 1 in which the desalination processing system 21 is arranged. While explaining.

  The cement raw material R pulverized by the raw material pulverizer 3 and supplied to the preheater 7 is preheated by the preheater 7, calcined by the calcining furnace 8, and then baked by the cement kiln 9 to generate clinker. . The clinker discharged from the cement kiln 9 is cooled by a clinker cooler 11 and pulverized with gypsum etc. in a subsequent cement pulverizing mill (not shown) to produce cement.

  On the other hand, the combustion exhaust gas G1 discharged from the preheater 7 is introduced into the waste heat power generation facility 2, and the heat held in the combustion exhaust gas G1 is recovered by the waste heat boiler of the waste heat power generation facility 2, and is generated in the waste heat boiler. Electricity is generated using steam. Then, the exhaust gas G2 having a temperature of about 150 ° C. discharged from the waste heat power generation facility 2 and passed through the raw material crushing device 3 is collected by the bag filter 4. The collected dust D is returned to the cement manufacturing process. On the other hand, about 150 ° C. exhaust gas G3 discharged from the bag filter 4 and passing through the fan 5 is used in the desalination treatment system 21 and then released from the chimney 6 to the atmosphere.

  Next, a method for desalting incinerated main ash using the desalination processing system 21 will be described with reference to FIG.

  As shown in the upper left cross-sectional view of FIG. 3, main ash A having a chlorine concentration of about 1% is introduced into the pit 22, and water W having the same weight as the main ash A is added, and the salts contained in the main ash A Is eluted in water W. At this time, the water temperature is preferably 30 ° C. or more, and the elution time is preferably 6 hours or more. After elution of the salts, the demineralized water W1 containing the salts is extracted from the pit 22. Thereby, desalted main ash A 'can be obtained. Here, the chlorine concentration of the desalted water W1 is about 0.4%.

  Next, the demineralized water W1 is concentrated using the concentrating device 23 shown in FIG. 2, and the concentrated water W2 containing about 2% of the chlorine content (1/5 of W1) and the water vapor containing almost no chlorine. Separated into S (4/5 of W1).

  Specifically, in FIG. 2, demineralized water W <b> 1 is introduced into the preheating pipe 32 by the pump 31 and heated by the exhaust gas G <b> 3 at about 150 ° C. passing through the flue 51. As a result, the demineralized water W1 is preheated to about 80 ° C., and the water vapor S generated at this time is taken into the condensing device 24 via the vapor transport pipe 38, and the unevaporated portion is temporarily stored in the first storage tank 34. After being stored, it is injected into the evaporative concentration pipe 33 on the upstream side by the pump 34. The demineralized water W1 is heated by the exhaust gas G3 in the evaporative concentration pipe 33, and the generated water vapor S is taken into the condensing device 24 via the vapor transport pipe 38, and the unevaporated portion (concentrated water W2) is discharged into the wastewater treatment facility by the pump 37. It is conveyed to.

  Next, the water vapor S obtained in the concentration step is sucked by the vacuum pump 41, the water vapor S is condensed by the cooling water supplied to the condensing device 24, and the generated condensed water W4 is conveyed to the pit 22 by the pump 42, Reuse for cleaning main ash A. On the other hand, since the concentrated water W2 includes heavy metals, it is discharged after being chelated in the wastewater treatment process. Concentrated water W3 from which heavy metals have been removed contains about 2% of chlorine, but since this concentration is similar to that of salt in seawater, it can be discharged as it is.

  As described above, in the present embodiment, the desalinated water W1 is concentrated by the concentrating device 23, and the condensed water W4 obtained by condensing the water vapor S generated by the concentration is circulated and used, so that only the concentrated water W2 is drained. In this case, the amount of the concentrated water W2 is 1/5 of the demineralized water W1, so that the waste water treatment facility can be greatly downsized.

Further, in condensing the desalted water W1, an exhaust gas G3 that has not been conventionally used is used. The exhaust gas G3 has a temperature of about 150 ° C. and an air volume of 2.0 Nm ³ / kg-cem (cement production facility 1 in order to have a large amount of heat of 2.0 Nm ³ occurs) approximately in fabricating 1kg of cement, it is possible to effectively utilize the waste heat, the exhaust gas G3 is not involved in the cement burning Therefore, it does not cause deterioration of the calorific value in cement firing.

  Moreover, in the said embodiment, since it uses the preheating pipe | tube 32 and the evaporative concentration pipe | tube 33, since it is the indirect heating using only the heat | fever which the waste gas G3 does not contact the waste gas G3 directly to the desalinated water W1, the desalted water There is no problem that fine dust in the exhaust gas G3 is mixed into W1.

  In the above embodiment, the case where the raw material crushing device 3 is arranged on the downstream side of the waste heat power generation facility 2 of the cement manufacturing facility 1 is illustrated, but a raw material drying device or the like is arranged instead of the raw material crushing device 3. The present invention can be applied even when an electric dust collector is arranged in place of the bag filter 4.

  In addition, the installation position of the desalination treatment system 21 in the cement manufacturing facility 1 is not limited between the fan 5 and the chimney 6, and may be between the bag filter 4 and the fan 5 and is discharged from the cement manufacturing facility 1. It is sufficient that a gas of 200 ° C. or lower can be used. Therefore, not only the combustion exhaust gas of the cement kiln 9 but also the exhaust from the clinker cooler 11 can be used.

  Further, in the above embodiment, the preheating pipe 32 of the concentrating device 23 is arranged on the downstream side of the flow of the exhaust gas G3, and the evaporation concentrating pipe 33 is arranged on the upstream side. On the contrary, the preheating pipe 32 is arranged on the upstream side. The evaporative concentration tube 33 can also be arranged on the downstream side.

DESCRIPTION OF SYMBOLS 1 Cement production facility 2 Waste heat power generation facility 3 Raw material crusher 4 Bag filter 5 Fan 6 Chimney 7 Preheater 8 Calciner 9 Cement kiln 11 Clinker cooler 21 Desalination processing system 22 Pit 23 Concentrator 24 Condenser 31 Pump 32 Preheating Pipe 33 Evaporative concentration pipe 34 First storage tank 35 Pump 36 Second storage tank 37 Pump 38 Steam transport pipe 41 Vacuum pump 42 Pump 51 Flue A Main ash A 'Desalination main ash G1 Combustion exhaust gas G2, G3 Exhaust gas S Water vapor R Cement raw material W Water W1 Demineralized water W2, W3 Concentrated water W4 Condensed water

Claims (2)

A pit for leaching the incinerated main ash to elute the salt, a concentration device for concentrating demineralized water containing the salt discharged from the pit with a gas of 200 ° C. or less discharged from the cement production facility, and the concentration a condensing device for condensing water vapor generated in the apparatus, a desalination system of baked却主ash that a circulating device for returning the condensed water generated by the condenser to the pit,
The concentrator is
A preheating pipe in which an outer surface is in contact with the gas flow of 200 ° C. or less and the demineralized water flows therein, and is disposed upstream of the preheating pipe in the gas flow of 200 ° C. or less, and the gas flow of 200 ° C. or less A desalination treatment system for incinerated main ash, comprising: an evaporative concentration pipe in which demineralized water preliminarily heated by the preheating pipe flows . The desalination treatment system for incinerated main ash according to claim 1, wherein the concentrating device is disposed in a flue upstream of a chimney that discharges cement kiln exhaust gas from the cement manufacturing facility to the atmosphere.

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