JPH11228979A - Production of finely powdered fuel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for producing a finely powdered fuel which exhibits a high combustion efficiency and is easily handled, mainly from org. dewatered sludge. SOLUTION: Dewatered sludge or dry sludge formed by drying dewatered sludge, plastic waste, and an additive are charged at a certain ratio into a twin-screw extruder and kneaded under heating to be converted into a solid contg. 10 wt.% or lower water. The solid is charged into a ball mill and pulverized, thus giving a finely powdered fuel having a particle size of 10-500 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a fine powder fuel from organic dehydrated sludge generated in a sewage treatment plant or a food production plant.

[0002]

2. Description of the Related Art Organic dewatered sludge generated in large quantities in sewage treatment plants and food manufacturing plants has a water content of 75 to 80%.
Since it is high in wt% and easily rotted, it is difficult to treat and is hardly used effectively. Most of them are landfilled as they are, or incinerated and disposed of in incinerated ash, and some are reused as fertilizer.

In recent years, there has been proposed a method for producing a solid fuel using the above-mentioned dewatered sludge as a main raw material. For example,
JP-A-8-176568 describes a method for producing a solid fuel by drying a dewatered sludge, adding a plastic waste to the sludge, and kneading the same.

(Problems of the Prior Art) The shape of the solid fuel produced by the above-mentioned method is a rod having a diameter of about 15 to 25 mm, or a granular or powder having a smaller size. In order to burn such a solid fuel, a dedicated boiler for a solid fuel or a powder fuel is generally used. However, there is a problem that the combustion efficiency is relatively low and the handling of the boiler is troublesome.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to use an organic dehydrated sludge as a main raw material to obtain a high combustion efficiency and a high handling efficiency. It is an object of the present invention to provide a method for producing a fine powder fuel which can be easily performed.

[0006]

According to the method for producing fine powder of the present invention, dehydrated sludge or dried sludge obtained by drying dehydrated sludge, plastic waste, and additives are charged into a twin screw extruder at a predetermined ratio, The mixture is kneaded with heating to change into a solid having a water content of 10% by weight or less. Then, the solid is put into a pulverizer and pulverized to a particle size of 10 μm or more.
It is characterized in that it is changed to a fine powder fuel of not more than 00 μm.

According to the method of the present invention, a fine powder fuel can be produced using dehydrated sludge as a main raw material. Further, the fine powder fuel obtained as a result has high combustion efficiency and is easy to handle, so that the reuse of the dehydrated sludge can be expanded.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an outline of a method for producing a fine powder fuel according to the present invention. Organic sludge generated from a sewage treatment plant is dehydrated by a centrifugal dehydrator and the
It becomes dewatered sludge of about 80 wt%, and is further dried by a dryer to become dry sludge having a water content of about 10 to 30 wt%. The dried sludge is put into a twin screw extruder together with the plastic waste, and further, an additive (described later) is added and kneaded while heating.

The plastic waste is (a) imparted to the input mixture fluidity to facilitate kneading, (b) functioning as a binder for molding into a solid, and (c) finally produced. It is added to dry sludge for the purpose of adjusting the calorific value of fuel. The mixing ratio between the dried sludge and the plastic waste is determined based on the target value of the calorific value of the finally produced fuel. As the above-mentioned plastic waste, it is desirable to reduce the volume of styrene foam generated as waste such as packaging materials, and other polyolefin-based plastic waste can also be used.

[0010] The additive performs a function of reducing the water content by chemically reacting with the residual water content in the dried sludge, thereby preventing rot and suppressing the generation of odor. As an additive having such a function, for example, quicklime is used.

The dried sludge and the plastic waste are kneaded while being heated in a twin-screw extruder, and most of the water contained in the dried sludge is released, and the water content is reduced to 10 wt%.
The following solids are discharged from the twin-screw extruder. The solid thus obtained is then charged into a ball mill and pulverized, and discharged from the ball mill as a fine powder fuel having a particle size of 10 μm to 500 μm. In addition, since the above-mentioned solid material has a fine powdery sludge as a main component, it can be relatively easily pulverized by loosely binding with a plastic (binder).

The fine powder fuel produced as described above is
Since the surface area of the fuel can be increased, the contact with the air is improved, and the fuel can be completely burned in a range where the excess air is small. Further, since the particle size is small, it can be burned into a furnace by a conventionally used burner for pulverized coal combustion. In addition, since the pneumatically-powder-type granular material carrier can be used for transportation, the transportation can be rationalized.

[0013] Instead of the dried sludge, the dewatered sludge before drying can be directly fed into a twin-screw extruder to dry the dewatered sludge in the twin-screw extruder. As the crusher, other rotary crushers such as a rod mill can be used in addition to the ball mill described above.

[0014]

According to the method for producing a fine powder fuel of the present invention, a fine powder fuel can be produced using organic dehydrated sludge as a main raw material. The resulting fine powder fuel has high combustion efficiency and is easy to handle, so that the reuse of the dewatered sludge can be expanded.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a method for producing a fine powder fuel according to the present invention.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Mitsuaki Serizawa 2068-3 Ooka, Numazu-shi, Shizuoka Toshiba Machine Co., Ltd. Numazu Office (72) Inventor Yoshiyoshi Katsuta 2068-3 Ooka, Numazu-shi, Shizuoka Toshiba Machine Numazu In business office

Claims (1)

[Claims] 1. A dewatered sludge or a dried sludge obtained by drying a dewatered sludge, a plastic waste, and an additive are charged into a twin-screw extruder at a predetermined ratio, and are kneaded with heating in the twin-screw extruder, whereby water content is 10 wt% or less. And then pulverize the solid by throwing it into a grinder,
A method for producing a fine powder fuel, wherein the fine powder fuel is changed to a fine powder fuel having a diameter of not less than m and not more than 500 μm.