JPS5947296A - Preparation of solid fuel from organic sludge - Google Patents

Abstract

PURPOSE:To prepare solid fuel without the need of any binder and without generation of harmful gas, by granulating dehydrated organic sludge, molding the dried granules by extrusion molding at a temperature and under a pressure which cause plasticization and then drying cut pieces by forced draft. CONSTITUTION:Organic sludge (e.g. those produced in pulp and fermentation industries) is dehydrated and crushed into small granules. The granules are dried to a water content of 5-25wt%. The dried granules are molded by extrusion molding. The formed product is cut and the cut pieces are cooled by forced draft into pellets of solid fuel. It has been a general practice to mix dehydrated and dried organic sludge with a binder (e.g. coal, tar, pitch or waste oil) for molding, but the method has a demerit in that it requires a large amount of binder which generates harmful gas in combustion. This invention eliminates such disadvantages.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing solid fuel from organic sludge.

In fields such as the pulp industry and the brewing industry, a large amount of sludge mainly composed of organic matter is generated. Most of these organic sludges are disposed of by incineration, ocean dumping, landfilling, etc., but these disposal methods not only require a large amount of cost but also cause environmental destruction. Recovery of organic sludge as a resource through anaerobic digestion, composting, thermal decomposition, etc. has been partially put into practical use, but efficiency and
It is not carried out on a large scale due to cost constraints.

Organic sludge is also converted into solid fuel and reused. Conventionally, in order to solidify organic sludge, the organic sludge was dehydrated and dried, and then kneaded with a binder (coal, tar, pitch, heavy oil, waste oil, etc.) and molded. However, this conventional method for producing solid fuel from organic sludge has the disadvantage of requiring a large amount of binder, and the binder generates harmful gases during combustion, making it difficult to use solidified fuel. It had the disadvantage of being restricted.

The present invention was made by focusing on the above-mentioned problems in the conventional method for producing solid fuel from organic sludge. Dry the raw material to reduce the moisture content to 5 to 25 (
% by weight as a dry raw material, extrusion molded at a temperature and pressure that plasticizes the dry raw material, cut the extruded molded product, and cooled the cut molded product with forced ventilation to form solid fuel pellets I. The purpose of this is to solve the above problems.

Hereinafter, the present invention will be explained based on the accompanying drawings.

The drawings show the steps of the method of the invention.

First, sludge whose main component is organic matter is dehydrated using a dehydrator to form a mass of organic sludge. If a high-performance dehydrator that is currently in practical use is used, it is possible to dehydrate to a water content of about 45 to 55% (by weight).

Next, the dehydrated organic sludge mass is crushed into small particles with a diameter of 10 mm or less using a crusher, and these are dried using a dryer (for example, a rotating drum dryer). This drying brings the moisture content of the small particulate raw material to 5 to 25% (by weight). It should be noted that if the moisture content of the dry raw material is less than 5%, it will not be plasticized in the die described below and will become powder-like and cannot be molded. Furthermore, if the moisture content of the dry raw material is 25% or more, it will be difficult to mold it because the specified pressure will not be reached in the die, and even if it can be molded, the pellets will be soft and lack compactness. becomes. A part of the dry raw material obtained by this process is used as a heat source for the dryer.

Dry raw materials are sent to a raw material storage tank by a conveyor and stored there. The dry raw material in the raw material storage tank is sent to a mixer by a quantitative feeder, stirred in the mixer, and then quantitatively fed to a continuous compression molding machine. The mixer has the function of uniformizing the particle size and properties of the dry raw material supplied to the continuous compression molding machine, thereby equalizing the load on the continuous compression molding machine and stabilizing the quality of the molded product.

A continuous compression molding machine consists of a cylindrical die that is rotationally driven by a motor, multiple rolls that are placed in contact with the inner diameter of the die, and a dry raw material that is evenly distributed between the inner diameter of the die and each roll. and a dispensing spreader. The die has a radial die hole extending from the inner diameter to the outer circumferential surface. The diameter of the die hole is 5-7 mm. The dry raw material supplied in a fixed amount to the inner diameter portion of the die is caught between the inner circumferential surface of the die and the outer circumferential surface of the roll, and is continuously extruded from the die hole. The dry raw material caught between the die and the roll is compressed, and when it passes through the die hole, it is heated at a temperature of 100 to 150°C and 400 to 8000 k.
A pressure of g / cm 2 is reached. Due to this high temperature and high pressure, the dried raw material is plasticized and becomes self-caking due to the oils, fats, lignin, etc. in the raw material, and also has high compactability. Also, when the raw material passes through the die holes,
Oil and fat in the raw materials ooze out to the surface, forming a hydrophobic film on the surface of the molded product. Therefore, the molded product has water resistance.

The cylindrical molded product extruded from the die hole is cut by a cutter knife provided close to the outer periphery of the die.
Cut into 20mm lengths. The pellets formed in this way are sent to a pellet storage container, where they are cooled by forced ventilation. This cooling significantly improves the mechanical strength of the pellets. Therefore, the pellets are prevented from being damaged during transportation, and handling as fuel is facilitated. Also, during cooling, part of the water in the pellets evaporates, reducing the water content by 2 to 3% (by weight), making the pellets more desirable as fuel.

Next, the material balance in a specific example in which the above method is implemented will be explained.

As a raw material, suspended solids (mainly composed of paper fibers and containing 14% (dry weight) of polyethylene) generated in the waste paper recycling process were used.

The calorific value of this suspended solid is 4960Kcal/k
g (dry weight). Wastewater containing the above suspended solids is dehydrated after sedimentation separation and contains 50% (by weight) of water 1
00 kg was used as the starting material. By crushing and drying this raw material, 39 kg of water was evaporated, but the remaining 61 kg
Of the 11.5 kg, 11.5 kg was used as fuel for drying.

Therefore, the dry raw material was 49.5 kg (in addition, the water content was reduced to 1
8% (by weight)) was obtained. This dried raw material was molded into pellets, cooled and dried by forced ventilation, resulting in a loss of 2 kg of water, resulting in a final product pellet weighing 47.7 kg (containing 15% (by weight) water). . That is, 47.7k from 100kg of starting material
g of product pellets could be obtained. In addition, the self-consumption rate of the dry raw material used for drying the starting raw material is (1
1,5/(11,5+49.5))X100=19%, and the total power consumption of Plan I is approximately 180KW.
H/l (product pellet).

As explained above, according to the present invention, dehydrated organic sludge, which is a raw material, is crushed into small particles, and this small particle-shaped raw material is dried to a moisture content of 5 to 25% (by weight). As a raw material, extrude it under the temperature and pressure that plasticizes the dry raw material, cut the extruded molded product,
Since the cut molded products are cooled with forced ventilation to form solid fuel pellets, it is now possible to use organic sludge, which was previously difficult to dispose of, as solid fuel. Since caking is utilized, no caking agent is required, and problems such as the cost of caking agent and the generation of malignant gas from the caking agent are eliminated.

In addition, Pellet I. has a diameter of 5 to 7 mm and a length of 15 to 2 mm.
It has a cylindrical shape with a diameter of 0 mm, and can be easily supplied automatically to combustion equipment and transported by air, and can be used as fuel in conventional coal boilers. It can be used with some modification. Furthermore, the equipment for implementing this method is a dehydrator, a crusher, a dryer, a molding machine, a cutting device (cutter knife), and a cooling device, and since the process is simple, the equipment is inexpensive.

[Brief explanation of the drawing]

The drawings are diagrams showing the steps of the present invention. Patent applicant: 1 Co., Ltd. Wooden Steel Works Agent: Patent attorney: Toshiyuki Miyauchi

Claims (1)

[Claims] The dehydrated organic sludge is crushed into small particles, this small particle material is dried to obtain a dry material with a water content of 5 to 25% (by weight), and this is heated at a temperature and pressure that plasticizes the dry material. extrusion molding, cutting the extruded molded product,
A method for producing solid fuel from organic sludge, in which cut molded products are cooled with forced ventilation to produce solid fuel pellets.