JP4958855B2 - Organic waste disposal methods - Google Patents

Description

  The present invention relates to a method for treating organic waste, and more particularly, to a method for drying or carbonizing organic waste using a combustion gas of a cement firing facility. Furthermore, the present invention relates to a method for treating organic waste that can supply dried or carbonized organic waste as a fuel or raw material to a cement firing process.

  In recent years, as a method for treating a large amount of industrial waste, a cement manufacturing facility has been used to treat these industrial waste. In addition, in addition to slag and coal ash that have been conventionally used as cement raw materials, the use of organic waste, which has been difficult to treat, is being studied and implemented in cement manufacturing facilities.

  In the rotary kiln of a cement baking apparatus, combustible waste is used as an alternative to some of these organic wastes. In particular, waste tires and waste plastics that have been cut or pulverized are directly put into a rotary kiln and burned to be used as part of the calorific value.

FIG. 2 is an overall configuration diagram of a conventional kiln with a new suspension preheater (NSP kiln). 1 is a rotary kiln which is a firing furnace, 2 is a suspension preheater, 3 is a clinker cooler, 4 is a calcining furnace, and 5 is a kiln bottom.
For example, waste tires or the like, which have been directly or shredded without pretreatment, are thrown into the kiln bottom part 5. In addition, waste plastics are usually crushed or pulverized to 20 to 30 mm or less and blown and combusted from the outlet of the kiln 1 or directly put into the calcining furnace 4 and combusted.

Recently, an organic waste that can be combusted but contains a lot of water is directly put into a rotary kiln and incinerated.
For example, as in Patent Document 1 below, a method of incinerating water-containing sludge directly into a kiln bottom portion of a rotary kiln or a calcining furnace without drying and without pretreatment with an additive There is.
Since most of the organic water-containing sludge is water and organic components, the amount of ash remaining after incineration is very small, and normal operation can be performed without affecting the quality of cement clinker.
Japanese Patent Laid-Open No. 2002-52397

  FIG. 3 is a diagram schematically showing a processing means for putting the water-containing sludge 6, which is an organic waste, into the rotary kiln kiln bottom 5 and performing an incineration process in the rotary kiln 1. As shown in FIG. 3, when the sludge is thrown into the rotary kiln kiln bottom 5, the charged high water content sludge is instantly evaporated and dehydrated in the rotary kiln 1, and the organic matter in the sludge is burned and incinerated. 7 is a pump for supplying the hydrous sludge 6 to the rotary kiln kiln bottom 5. The hydrous sludge can also be supplied to the calcining furnace 4.

  However, in the use or treatment of organic waste that contains a lot of moisture, the method of directly feeding these wastes into the rotary kiln is the same as the temperature of the raw material at the bottom of the rotary kiln kiln as the moisture in the waste evaporates. There is a risk that the quality of the fired cement clinker may deteriorate due to a decrease, a decrease in latent heat of the raw material, or a decrease in the temperature of a zone where the cement raw material is sintered in a clinker shape (kiln firing zone).

  For this reason, it is necessary to limit the input amount of organic waste, and in the case of combustible waste such as waste tires and plastics, the direct input amount is less than 10% of the fuel consumption used in the rotary kiln. On the other hand, organic waste with a high water content is limited to several weight percent with respect to the clinker firing amount.

In order to increase the amount of organic waste used, in Patent Document 2 below, a suspension preheater equipped with a calciner is connected to the raw material input side of the rotary kiln, and a cooler is connected to the clinker discharge side of the rotary kiln. In the cement raw material firing apparatus, in the duct for introducing the high temperature air generated in the cooler into the calcining furnace, the combustible industrial waste is carbonized using a part of the high temperature air, and the combustible carbonization gas There is disclosed a cement raw material calcining apparatus in which a gas generating device for generating the gas is provided and a burner for calcining the cement raw material using the dry distillation gas as fuel is provided in the duct.
With this configuration, combustible waste, in particular, waste tires are not put directly into the rotary kiln, but the waste tires are carbonized outside the cement firing facility, and the carbonized gas is used in a calcining furnace to make combustible. It is intended to increase the amount of waste used.
JP-A-11-292580

In addition, in the following Patent Document 3, incineration of waste combustible material is performed in order to prevent a blockage of the flow path even if a large amount of industrial waste is processed and industrial waste containing chlorine is supplied to the NSP kiln. There is disclosed a waste treatment apparatus for cement firing including an incineration apparatus including a burner and an ash supply apparatus that supplies only incineration ash generated by incineration to a cement firing facility.
JP 11-294960 A

However, in the combustible waste treatment apparatus installed outside the cement burning facilities of Patent Documents 2 and 3, not all of the combustion heat of the combustible waste is used effectively, and a separate burner is provided. It is necessary to burn the fuel, which results in extra fuel consumption.
Moreover, in patent document 2, there exists a problem that processing efficiency is inferior because dry distillation is indirect heating, and it is not generalized to the actual cement baking equipment.

  The present invention solves the various problems described above and can treat not only flammable waste such as waste tires and waste plastics, which can easily use heat, but also sludge containing a large amount of moisture, An object of the present invention is to provide a method for treating organic waste with improved treatment capacity.

  In order to solve the above-mentioned problem, the invention according to claim 1 is provided with a device for drying or carbonizing organic waste with a high-temperature gas discharged in a cement firing step, and a dried product after being processed by the device. Or it is the processing method of the organic waste characterized by utilizing a carbide | carbonized_material for a cement baking process.

  In particular, the invention according to claim 1 is characterized in that the high-temperature gas is a mixture of kiln bottom exhaust gas extracted directly from a cement rotary kiln bottom and suspension preheater exhaust gas.

  The invention according to claim 2 is characterized in that in the organic waste treatment method according to claim 1, the oxygen concentration contained in the high-temperature gas is 10% or less.

  Moreover, in the invention which concerns on Claim 3, in the processing method of the organic waste of Claim 1 or 2, the said apparatus to dry or carbonize is a rotary kiln, Comprising: Hot gas and organic waste Are characterized in that they are processed in parallel.

According to the first aspect of the invention, in order to dry or carbonize organic waste with the high temperature gas discharged in the cement firing process, organic waste is obtained using the high temperature gas obtained by separately burning conventional fuel. Compared with the method of processing a thing, it becomes possible to aim at the effective utilization of the thermal energy which generate | occur | produced in the cement baking equipment.
In addition, the organic waste used in the cement firing process is a dried or carbonized product after drying or carbonization, so it is compared with the conventional treatment method that is put directly into the cement firing equipment without pretreatment. Since the influence on the cement baking process can be suppressed, the amount of organic waste that can be processed can be increased.

In addition, the high temperature gas is a mixture of kiln bottom exhaust gas extracted directly from the cement rotary kiln bottom and suspension preheater exhaust gas. It can also be used. Thereby, carbonization suitable as a fuel becomes possible corresponding to the characteristics of the organic waste, and the utilization efficiency in the cement firing process is increased. Moreover, by changing the mixing ratio of the kiln bottom exhaust gas of the cement rotary kiln and the exhaust gas of the suspension preheater, the gas temperature can be freely changed while maintaining a low oxygen concentration.
Furthermore, the kiln exhaust gas contains a large amount of calcium oxide powder generated from the cement raw material, and it is decomposed even when chlorinated organic substances such as vinyl chloride are present in the organic waste to be dried or carbonized. Acidic gases such as hydrogen chloride gas are immediately neutralized to form calcium salts such as calcium chloride. For this reason, discharge | release to the exterior of acidic gas can be suppressed.

  According to the invention of claim 2, since the oxygen concentration contained in the high-temperature gas is 10% or less, the treatment by direct contact between the organic waste and the high-temperature gas becomes possible, and the treatment capacity for drying or carbonization is increased. Can do.

  According to the invention of claim 3, since the apparatus used for the drying process or the carbonization process is a rotary kiln, the high-temperature gas and the organic waste can be processed in parallel, and the organic waste is disposed in the treatment apparatus. There is no problem such as burning, and the amount of carbonization is improved.

Embodiments of the present invention will be described below.
FIG. 1 shows a schematic diagram of a cement baking apparatus used in the organic waste processing method according to the present invention. In the present invention, the embodiment shown in FIG. 1 is not particularly limited as long as the organic waste is dried or carbonized using the high-temperature exhaust gas from the cement firing facility.

  In the present invention, the organic waste is dehydrated to a state where it can be easily pulverized and converted into fuel. Preferably, it is dried or carbonized until it can be handled in the same manner as the solid fuel for cement firing, and burned as a powdered fuel from the burner of the cement firing facility.

Hereinafter, with reference to FIG. 1, the embodiment of the processing method of the organic waste which concerns on this invention is demonstrated.
In FIG. 1, a system for drying or carbonizing organic waste includes a drying / carbonizing device 12 for drying or carbonizing the organic waste 6 and supplying the organic waste 6 to the drying / carbonizing device 12. A high temperature exhaust gas is extracted from the supply device and the cement firing equipment and sent to the drying / carbonization device, the gas line 14 returns the exhaust gas discharged to the cement firing device, and the dried or carbonized organic waste is coal. It is comprised from the apparatus etc. which supply to the mill 21.

The apparatus for supplying the dried or carbonized organic waste to the coal mill 21 separates the fine dust contained in the exhaust gas of the drying / carbonizing apparatus 12 by the cyclone 13, and the dried or carbonized organic waste is separated from the fine dust. Supply together with things.
However, when the dust collected in the cyclone 13 contains a large amount of a calcined material of cement material generated as dust in a cement rotary kiln, other inorganic materials such as other volatile components of chlorine and metals, It is preferable to perform a separate process without supplying to the coal mill 21.

  Further, depending on the properties of the dried or carbonized organic waste, the dried or carbonized material may be directly put into the calcining furnace 4 and combusted without being pulverized.

The drying / carbonizing apparatus 12 in this configuration is not limited to the rotary kiln system. However, for example, when the rotary kiln system is employed, the drying / carbonizing apparatus 12 has the following advantages.
In the rotary kiln system, the extracted high-temperature exhaust gas and organic waste can be processed in parallel . By co-currently processing the gas and the organic waste, the high temperature gas in the rotary kiln is preferentially used as the evaporation of moisture and volatile components contained in the organic waste or the volatile latent heat. For this reason, the organic waste does not reach an unnecessarily high temperature, and reburning of the dried or carbonized organic matter can be prevented.

In the rotary kiln system, the gas temperature at the entrance can be adjusted in accordance with the degree of drying or carbonization required for organic waste.
As a method for adjusting the temperature of the gas supplied to the inlet, the temperature of the high temperature exhaust gas from the cement rotary kiln kiln bottom 5 is adjusted by adjusting the mixing ratio of the exhaust gas in the suspension preheater 2. Reference numeral 15 denotes an exhaust gas extraction line from the suspension preheater.

  Usually, the kiln bottom exhaust gas of a cement rotary kiln is 900-1000 degreeC, and oxygen concentration is 3% or less. In the exhaust gas of the suspension preheater, the temperature is 300 to 370 ° C. and the oxygen concentration is 5% or less. As described above, by changing the mixing ratio of the kiln bottom exhaust gas of the cement rotary kiln and the exhaust gas of the suspension preheater, the gas temperature can be freely changed while maintaining the low oxygen concentration.

In general, a large amount of exhaust gas extracted from the cement rotary kiln kiln bottom 5 reduces the cement clinker bake-out ability in the cement firing facility and deteriorates the thermal efficiency.
However, when organic waste such as waste wood is used, heat that exceeds the amount of heat reduced by exhaust gas extraction is generated by supplying dried or carbonized organic waste as fuel to cement firing equipment. It is also possible to make it.

If high-temperature exhaust gas is required without increasing the amount of extracted gas from the bottom of the cement rotary kiln, install a separate combustion device and heat the extracted gas before introducing the extracted gas into the drying / carbonizing device. This can also be achieved.
That is, in the organic waste processing method of the present invention, the degree of drying or carbonization of the organic waste is determined according to the properties of the organic waste to be processed. In order to obtain the supply amount and temperature of the gas necessary for the determined drying or carbonization treatment, or the gas component, the position and amount of extraction from the cement firing facility are determined. Further, an appropriate device such as the above-described combustion device is selected as necessary.

The organic waste applicable to the present invention is not limited to waste tires and waste plastics, and waste wood, organic municipal waste, paper sludge, sewage sludge, and the like can be used.
In organic waste such as waste wood having a relatively low water content, it is preferable to increase the amount of extracted gas from the bottom of the cement rotary kiln and carbonize it at a high temperature. The obtained carbide is preferably pulverized by a coal mill, mixed with other powdered fuel from a burner of a cement firing furnace, and used for combustion.

On the other hand, in the case of sludge, it usually contains more than 80% of moisture, and the treatment in the organic waste treatment equipment can only evaporate the moisture contained in the sludge, and the dried organic matter can be directly fed into the cement rotary kiln. Is possible.
Thereby, in the state of the high water content sludge performed conventionally, compared with the method of throwing in and directly processing to a cement rotary kiln kiln bottom, the amount which can be processed increases remarkably.

  As described above, according to the method for treating organic waste according to the present invention, not only combustible waste such as waste tires and waste plastics, which can easily use heat, but also sludge containing a large amount of moisture, etc. Therefore, it is possible to provide a method for treating organic waste with improved treatment capacity.

It is a figure which shows embodiment of the processing method of the organic waste of this invention. It is a figure which shows the whole structure of the conventional NSP kiln. It is a schematic diagram which throws in sludge organic waste to a NSP kiln.

Explanation of symbols

1 Firing furnace (rotary kiln)
2 Suspension preheater 3 Clinker cooler 4 Calciner 5 Kiln bottom 6 Organic waste 7 Sludge supply pump 11 Kiln bottom gas extraction line 12 Drying or carbonization device (rotary kiln method)
13 Cyclone 14 Exhaust gas line 15 of drying or carbonization equipment Suspension preheater exhaust gas extraction line 16 Drying or carbide transport line 21 Coal mill

Claims (3)

  In the cement firing process, a device for drying or carbonizing organic waste with high-temperature gas discharged is provided, and the organic waste is treated using the dried or carbonized material in the cement firing process after being treated in the device. A method for treating organic waste, characterized in that the high-temperature gas is a mixture of kiln bottom exhaust gas extracted directly from a cement rotary kiln bottom and suspension preheater exhaust gas.   2. The method for treating organic waste according to claim 1, wherein the oxygen concentration contained in the high-temperature gas is 10% or less.   The organic waste processing method according to claim 1 or 2, wherein the drying or carbonizing apparatus is a rotary kiln, wherein the high-temperature gas and the organic waste are processed in parallel flow. To treat organic waste.

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