JP4596768B2 - Method of manufacturing cement raw material from sewage sludge using carbide - Google Patents

Description

  The present invention relates to a method for improving the efficiency of sewage sludge cement recycling equipment using carbides, and more specifically, cement from sewage sludge using carbides produced by carbonizing garbage, refuse solid fuel (RDF), sludge, etc. The present invention relates to a method capable of producing a raw material at a low running cost. Note that RDF is an abbreviation for “fused derived fuel”, which is a solid waste fuel obtained by drying, solidifying, and molding waste.

Conventionally, as a manufacturing method of raw materials for cement production from sewage sludge, sewage sludge is dehydrated and dried to dry sludge, and raw lime is mixed with dry lime to obtain dry powder. In the manufacturing method, a configuration is known in which the moisture content of the dried sludge is always automatically measured, and the amount of quicklime added to the dried sludge is automatically adjusted based on the measured value (for example, Patent Document 1). reference).
Japanese Patent Laid-Open No. 11-35351 (second page, FIG. 1)

  The problem to be solved is that, in the method as described in Patent Document 1, the dry powder produced from the facility for converting raw lime into cement raw material contains about 44% as quick lime and about 58% as slaked lime. In addition to having to purchase, the amount to be carried out of the field is about half of the actual amount carried out, and the running cost is increased.

  In order to reduce the running cost in a sewage sludge cement recycling facility, the present invention accepts a carbide in a sewage treatment plant having a cement recycling facility, and a dehydrator located upstream of the sewage sludge cement recycling facility. The main feature is the use of carbide as a dehydrating aid. The reduction in drying load due to the dehydration aid effect is adjusted by reducing the amount of quicklime used.

  Moreover, in the method of the present invention, the amount of dehydrated sludge generated can be reduced by about 3 to 20% by adding carbide, and the water content of the dehydrated sludge is reduced. In the dryer or / and the aging machine, the amount of fuel used in the steam generator, such as kerosene or / and quicklime, can be reduced. In addition, the sewage treatment plant can obtain income from receiving the carbide, and can reduce the running cost by reducing the amount of fuel (for example, kerosene) and / or chemicals used.

  The method of producing cement raw material from sewage sludge using the carbide of the present invention, after introducing the concentrated sludge from the drainage / sludge treatment facility for treating sewage into a dehydrator and dewatering it into dehydrated sludge, This dehydrated sludge is introduced into a dryer and dried, and then the dried sludge is introduced into a aging machine together with quick lime and aged to be used as a cement raw material. The use of carbide as a dehydrating aid is characterized by the above.

Since this invention is comprised as mentioned above, there exist the following effects.
(1) The amount of quicklime used in cement recycling facilities for sewage sludge can be reduced. It is possible to reduce about 31% by trial calculation. Moreover, the amount of cement raw material carried out of the field does not change. From these things, the running cost in the cement resource conversion equipment of sewage sludge can be reduced significantly.
(2) Addition of carbide increases the silica content, but this is not a problem because it is a component used as a cement raw material. In addition, if the disposal cost of carbide can be collected, the economic advantage will be greater.

  Concentrated sludge and carbide are supplied to the dehydrator located upstream of the sewage sludge cement recycling facility, and the carbide is used as a dehydrating aid, with the aim of reducing running costs in the sewage sludge cement recycling facility. It was realized by doing.

  Embodiments of the present invention will be described below, but the present invention is not limited to the following embodiments, and can be implemented with appropriate modifications. FIG. 1 shows an apparatus for carrying out a method for producing a cement raw material from sewage sludge using carbide according to the first embodiment of the present invention. Reference numeral 10 denotes a sewage treatment plant, and a cement recycling facility 12 is installed in the sewage treatment plant 10. 14 is a wastewater / sludge treatment facility for treating sewage, 16 is a dehydrator (for example, belt press dehydrator, screw press dehydrator, centrifugal dehydrator, rotary press dehydrator, filter press dehydrator, (Multiple disk type dehydrator), 18 is a dryer (for example, a steam indirect heating type dryer), and 20 is an aging machine (for example, a single screw paddle type mixer or a twin screw paddle type mixer).

  In the apparatus configured as described above, after the concentrated sludge from the drainage / sludge treatment facility 14 for treating sewage is introduced into the dehydrator 16 and dehydrated to obtain dehydrated sludge, the dehydrated sludge is dried into the dryer 18. And then dried indirectly with steam, and then the dried sludge is introduced into the aging machine 20 together with quick lime to evaporate and age the moisture using the reaction heat when quick lime changes to slaked lime. Manufacturing. In this cement raw material manufacturing method, the concentrated sludge is introduced into the dehydrator 16 together with carbides, and the carbides are used as a dehydrating aid. The carbide is produced by carbonizing waste, solid waste fuel (RDF), sludge, and the like. Although this carbide is supplied from outside the sewage treatment plant 10, it is also possible to provide a carbide production device in the sewage treatment plant.

Next, the mass balance in the dryer 18 and the aging machine 20 was calculated. FIG. 2 shows a conventional case in which no carbide is used, for example, the mass balance by the method shown in the above-mentioned Patent Document 1, and FIG. 3 shows a case in which carbide by the method of the present invention is used. A steam indirect heating twin disk dryer was used as the dryer 18, and a uniaxial paddle type mixer was used as the aging machine 20. The amount of heat # 1 indicates the amount of heat retained on a 0 ° C. basis.
The trial calculation conditions are as follows. Due to the effect of the dehydration aid, the water content of the dewatered sludge is reduced. For this reason, the amount of quicklime required for drying of the sludge with an aging machine can be reduced. Furthermore, in order to reduce the amount of quicklime used, it is assumed that the amount of dry (dry powder) to be carried out does not change.
Moreover, although the original amount of sludge solids is the same, the moisture of the same weight as the added amount of carbide can be dehydrated by the effect of the dehydration aid. The amount of quicklime used in the aging machine was investigated under the condition that the heat load of the dryer was almost unchanged.

  As a result, in the conventional example of FIG. 2, the quicklime requirement is 9.6 t / d, but in the case of the present invention in FIG. 3, the quicklime requirement is 6.6 t / d, and the quicklime requirement can be reduced by about 31%. . The amount of dry (dry powder) generated was 22.0 t / d and was not changed.

  In the end, I will consider about the dry powder. Table 1 summarizes the composition of sludge, carbide, and lime for each component content in the dry state.

  Moreover, when the components of the camp (dry powder) in each case are compared and the camp is evaluated, Table 2 is obtained. In addition, most of the water is accompanied by slaked lime in which quick lime has changed.

  In addition, the ash content of dry powder in each case is evaluated. The organic component contained in the camp is burned during cement production, and the remaining ash becomes the cement itself. Table 3 shows the ash content in the conventional case, and Table 4 shows the ash content in the case of the present invention.

It is a schematic block diagram of the apparatus which enforces the method of manufacturing a cement raw material from sewage sludge using the carbide | carbonized_material of this invention. It is explanatory drawing which shows the material balance in the dryer and aging machine in a prior art example. It is explanatory drawing which shows the material balance in the dryer and aging machine in the method of this invention.

Explanation of symbols

10 Sewage Treatment Plant 12 Cement Resource Recycling Equipment 14 Wastewater / Sludge Treatment Equipment 16 Dehydrator 18 Dryer 20 Aging Machine

Claims (1)

Concentrated sludge from the wastewater / sludge treatment facility for treating sewage is introduced into a dehydrator and dehydrated to obtain dehydrated sludge. Then, the dehydrated sludge is introduced into a dryer and dried. In the method for producing a cement raw material which is introduced into an aging machine and aged to be a cement raw material, the concentrated sludge is disposed of, and introduced into a dehydrator together with a carbide produced by carbonizing at least one of the solid waste fuel and sludge , A method for producing a cement raw material from sewage sludge using a carbide, characterized in that the carbide is used as a dehydrating aid in producing the cement raw material.