JPH0153213B2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention is aimed at uniformly converting coal ash and sewage sludge incineration ash into granular combustible materials piled up in the sintering cart of a downward suction sintering furnace. The present invention relates to a method for igniting a fire.

(Prior technology) Combustible materials such as pulverized coal are added to coal ash, garbage, sewage sludge incineration ash, etc. and granulated, and this granular combustible material is sintered to produce lightweight aggregate using a downward suction method. The use of a sintering furnace is widely known, for example from Japanese Patent Publication No. 58-3989, but conventionally an ignition lid equipped with multiple burners was placed on top of a sintering cart loaded with granular combustible materials. At the same time as the lid was closed, air was sucked in from below the sintering cart to ignite it.
Normally, combustion started from the center of the particulate combustible material inside the sintering cart and sintering progressed as the combustion part gradually moved outward. However, with this combustion method, the particulate combustible material in the center of the sintering cart tends to reach an excessively high temperature and form clinker, while the temperature in the periphery does not rise sufficiently and sintering tends to be insufficient. There were flaws. Also, attempts have been made to directly ignite the granular combustible materials in the sintering truck with a burner, but this method has the disadvantage that ignition becomes even more uneven.

(Objective of the Invention) The present invention solves these conventional drawbacks, and uniformly ignites the entire surface layer of the granular combustibles in the sintering cart, thereby making the combustion temperature and combustion time of the granular combustibles uniform. This was completed with the aim of creating a method for igniting granular combustible materials in a downward suction sintering furnace, which allows for the production of homogeneous lightweight aggregates.

(Structure of the Invention) The present invention involves piling up granular combustible material, which is made by adding combustible material to incinerated ash such as coal ash or sewage sludge incineration ash, in a sintering cart of a downward suction sintering furnace, and sintering the combustible material. An ignition lid is placed on the top of the sintering cart to fill the upper space of the sintering cart with volatile gas generated from the combustible particles. It is characterized by uniformly igniting the entire surface layer of a combustible material, and will be described in detail below with reference to illustrated embodiments.

1 is a hopper for storing powder raw materials such as coal ash, garbage, sewage sludge incineration ash, etc. to which combustible materials such as pulverized coal and dried sludge powder are added; 2 is a hopper for storing powder raw materials supplied from the hopper 1; A humidifying kneader adds an appropriate amount of moisture and kneads the mixture, and 3 is a pan-type granulator. The granular combustible material granulated to a particle size of 1 to 15 mm by the pan-type granulator 3 is moved intermittently over a large number of wind boxes 6 by a box-shaped sintering cart 5 having a grate 4 at the bottom. The materials are stacked in the sintering cart 5 of the downward suction sintering furnace 7 so as to have a thickness of 200 to 400 mm. An ignition lid 8 equipped with a large number of burners is provided at the rear of the granular combustible material charging position of the downward suction type sintering furnace 7, and is movable up and down.As shown in FIG. The high temperature ignition lid 8 is closed. During this time, the damper 9 of the wind box 6 directly below the ignition lid 8 is closed, so if this state is maintained for 30 to 90 seconds, volatile gas will be generated from the combustible particles heated by the ignition lid 8, and the sintering cart 5 will be heated. Upper space 1
At the same time, a dry region 20 is formed on the surface layer of the combustible particles. The actual measured value of this gas concentration is
CO1000~1500ppm, _CH4 200~400ppm, _H2200
~400ppm, but if there are few volatile components in the particulate combustible material, the combustible gas concentration will be at least
Gas may be injected from the outside until a reducing atmosphere of 1000 ppm is achieved. Next, as shown in FIG. 3, if the damper 9 of the wind box 6 is opened with the ignition lid 8 closed, the air inside the sintering cart 5 will be sucked downward, and the ignition lid 8 and the sintering cart will be sucked downward. Outside air is introduced through the gap with the sintering cart 5, and the volatile gas filling the upper space 10 of the sintering cart 5 is explosively combusted in an instant. Since this combustion occurs throughout the interior of the upper space 10, the entire surface layer of the granular combustibles piled up on the sintering cart 5 is ignited uniformly, and then the ignition lid 8 is raised and the wind box 6 sucks it downward. If the sintering cart 5 is sequentially moved rearward while continuing, the combustion surface 11 will move downward while maintaining an almost horizontal state, as shown in FIG. A homogeneously sintered lightweight aggregate 21 with a uniform combustion temperature is obtained. Note that this combustion temperature and combustion time can be arbitrarily changed by changing the downward suction air volume by adjusting the opening degree of each damper 9. If the air volume is large, the cooling effect due to outside air suction will be large. As a result, the combustion temperature does not rise sufficiently and unburned materials tend to remain. Conversely, if the air volume is low, heat transfer is slow,
Since the heat retention effect becomes large and clinker is likely to occur, it is necessary to adjust the air volume to an optimum value between these two. In this way, the granular combustible material is homogeneously sintered into lightweight aggregate, which is separated by particle size by a classifier 12 provided at the rear end of the downward suction sintering furnace 7 and shipped.

(Effects of the Invention) As is clear from the above description, the present invention covers the ignition lid on the top of the sintering cart stacked with granular combustible materials to fill the upper space of the sintering cart with volatile gas. After that, outside air is introduced by suction from below to cause explosive combustion, which uniformly ignites the entire surface layer of the granular combustible material.
As a result, the entire particulate combustible material in the sintering cart can be sintered at a uniform temperature and for a uniform time, and lightweight aggregate with uniform properties can be obtained.
This method will greatly contribute to the development of industry by eliminating the drawbacks of the conventional method of igniting combustible particles in the downward suction sintering furnace.

[Brief explanation of drawings]

FIG. 1 is a flow sheet of a downward suction sintering furnace used for carrying out the present invention, and FIGS. 2, 3, and 4 are process explanatory diagrams of the present invention.

Claims (1)

[Claims] 1 Pile up granular combustibles made by adding combustible materials to incinerated ash such as coal ash or sewage sludge incineration ash in the sintering cart of a downward suction sintering furnace, and place an ignition lid on the top of the sintering cart. After closing the lid and filling the upper space of the sintering cart with volatile gas generated from granular combustible materials, outside air is introduced by suction from below to cause explosive combustion.
A method for igniting granular combustible material in a downward suction sintering furnace characterized by uniformly igniting the entire surface layer of the granular combustible material.