METHOD AND APPARATUS FOR TREATING COMBUSTIBLE SUBSTANCE

Abstract

A treatment method and apparatus is provided to effectively use a combustible waste such as waste plastic, waste tires, rice husk, wood shavings, PKS, RDF and sludge while maintaining stable operation; to improve the combustion efficiency of a fossil fuel such as coal and coke; and furthermore to reduce the NOx concentration in a cement kiln exhaust gas. An apparatus 1 for treating a combustible, the apparatus comprising: a mixer 3 for mixing a combustible C with a preheated raw material R2, which has a temperature of 600° C. or higher and 900° C. or lower and which is drawn from a preheater cyclone of a cement burning device 10, to gasify the combustible; and a feeder 5 for feeding the gasified combustible and the preheated raw material (mixed raw material M) to a region from an inlet end 13a of the cement burning device to a calciner 12. When the combustible and the preheated raw material are mixed, moisture may be added to cause water gas shift reaction, and the resultant water gas and the preheated raw material may be introduced to the region from the inlet end of the cement burning device to the calciner.

Claims

1. A combustible treatment method comprising the steps of: mixing a combustible with a preheated raw material, which has a temperature of 600° C. or higher and 900° C. or lower and which is drawn from a raw material chute of a preheater cyclone of a cement burning device, to gasify the combustible; and feeding the gasified combustible and the preheated raw material to a region from an inlet end of the cement burning device to a calciner.

2. The combustible treatment method as claimed in claim 1, wherein when the combustible and the preheated raw material are mixed, moisture is added to cause water gas shift reaction, and the resultant water gas and the preheated raw material are introduced to the region from the inlet end of the cement burning device to the calciner.

3. A combustible treatment apparatus comprising: a mixer for mixing a combustible with a preheated raw material, which has a temperature of 600° C. or higher and 900° C. or lower and which is drawn from a raw material chute of a preheater cyclone of a cement burning device, to gasify the combustible; and a feeder for feeding the gasified combustible and the preheated raw material to a region from an inlet end of the cement burning device to a calciner.

4. The combustible treatment apparatus as claimed in claim 3, further comprising a moisture adding device for adding moisture to the mixer to cause water gas shift reaction.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0019] FIG. 1 is a schematic view showing a combustible treatment apparatus according to an embodiment of the present invention.

DETAILED DESCRIPTION

[0020] FIG. 1 shows a combustible treatment apparatus according to an embodiment of the present invention, and the treatment apparatus 1 is provided with a hopper 2 for receiving a combustible C, a mixer 3 for gasifying the combustible C supplied from the hopper 2 by mixing the combustible C with a preheated raw material R2 of 600° C. or higher and 900° C. or lower, which is drawn from a cyclone 11B in the second stage from the bottom of a preheater 11 of a cement burning device 10, and a feeder 5 for suppling the gasified combustible C and the preheated raw material R2 (including a non-gasified combustible C, hereinafter referred to as “mixed raw material M”) to a region from an inlet end 13a of a cement kiln 13 to a calciner 12 of the cement burning device 10. Although two cyclones 11B are drawn in FIG. 1 for the convenience of explanation, they are the same.

[0021] The combustible C to be treated includes a combustible waste such as waste plastic, waste tires, rice husk, wood shavings, PKS, RDF and sludge, and a fossil fuel such as coal and coke.

[0022] The mixer 3 is a pug mill or the like in which many blades 3b are attached to a horizontal shaft 3a, and rotating the horizontal shaft 3a allows the blades 3b to be rotated also, and mixes the combustible C with the preheated raw material R2 to gasify the combustible C.

[0023] A water spray device (not shown) is provided above the mixer 3, and sprays water into the mixer 3 (moisture W is supplied) to carry out water gas shift reaction. The mixer 3 is provided with a hood 3c in order to prevent scattering dust from increasing due to the sudden generation of water vapor.

[0024] A shut damper 4 is installed below the mixer 3, and introducing a mixed raw material M to the region from the inlet end 13a of the cement kiln 13 to the calciner 12 of the cement burning device 10 via the feeder 5 while maintaining airtightness. Further, an exhaust duct 6 for discharging the gasified gas G is provided, and the gas G discharged from the exhaust duct 6 merges with the mixed raw material M below the shut damper 4, and is introduced into the region from the inlet end 13a of the cement kiln 13 to the calciner 12 of the cement burning device 10 via the feeder 5. As the feeder 5, a chute, a duct or a transporter is used.

[0025] The cement burning device 10 to which the processing device 1 is attached is provided with the preheater 11 for preheating the cement raw material R1, the calciner 12 for calcining the preheated raw material R2 from the cyclone 11B in the second stage from the bottom of the preheater 11, the cement kiln 13 for firing the raw material R3 from the lowermost cyclone 11A of the preheater 11 with the fuel F blown from the main burner 15, a clinker cooler 14 for cooling cement clinker fired in the cement kiln 13, and the like, and these components are identical to the conventional ones. It is preferable that at the supply position of the mixed raw material M with the feeder 5, the powder or granular material dispersion device of Japan Patent No. 6396433 by the present applicant is installed, and the gasified combustible C and the preheated powdery raw material are effectively dispersed into the gas.

[0026] Next, a method for treating combustible with the treatment device 1 will be described with reference to FIG. 1.

[0027] During the operation of the cement burning device 10, the combustible C received in the hopper 2 is supplied to the mixer 3, and a part of the preheated raw material R2 discharged from the cyclone 11B of the preheater 11 is drawn, and the drawn raw material R2 is introduced into the mixer 3. The preheated raw material R2 that is not drawn is decarbonated in the calciner 5 and the lowermost cyclone 11A as usual, and then fired in the cement kiln 13 to generate cement clinker.

[0028] In the mixer 3, the combustible C and the preheated raw material R2 are conveyed while being mixed and stirred, and the combustible C is heated and gasified with the separated preheated raw material R2, and water is sprayed from the water spray device to carry out water gas shift reaction. Mixing the combustible C with the preheated raw material R2 avoids adhesion trouble due to tar generated during gasification. Further, acid gas generated from the combustible C can be fixed to the preheated raw material R2. In addition, since combustion time can be shortened through gasification, it can be effectively burned even in the conventional calciner 12 for coal combustion, and the amount of coal used and the amount of CO generated can be reduced.

[0029] The mixing ratio of the combustible C and the preheated raw material R2 is not particularly limited, but when the combustible C adheres to the inside of the mixer 3 or the transport path, the mixing ratio of the preheated raw material R2 is increased. Further, when treating waste plastic or the like, it is preferable to crush it to approximately 200 mm or less in advance in the front stage of the mixer 3. Further, it is preferable that the residence time of the combustible C in the mixer 3 is 5 to 15 minutes, the rotation speed of the horizontal axis 3a of the mixer 3 is variable, and the residence time can be adjusted.

[0030] Further, since the mixer 3 is sealed with water vapor without introducing oxygen, there is no danger of explosion, and a reducing agent H2 is generated though water gas shift reaction, and since Fe2O3 in the preheated raw material R2 is also reduced to FeO, the amount of reducing agent increases dramatically.

[0031] The mixed raw material M discharged from the mixer 3 is supplied to the region from the inlet end 13a of the cement kiln 13 to the calciner 12 of the cement burning device 10 with the feeder 5 via the shut damper 4. As described above, since the amount of reducing agent is dramatically increased, NOx in the cement kiln combustion gas can be effectively reduced. Further, among the mixed raw materials M, the non-gasified combustible C is used as a fuel substitute in the calciner 12, and the preheated raw material R2 drawn is decarbonated in the calciner 12 and the lowermost cyclone 11A and is fired in the cement kiln 13 to produce cement clinker.

[0032] In the above embodiment, the preheated raw material R2 is drawn from the cyclone 11B of the preheater 11, but it may be drawn from other parts if the temperature of the cement raw material to be drawn is 600° C. or more and 900° C. or less.

[0033] Further, a water spray device is provided and water is sprayed into the mixer 3 to carry out water gas shift reaction in the above embodiment. Without spraying water, simply mixing the combustible C with the drawn preheated raw material R2 for gasification avoids adhesion trouble due to tar generated during gasification, and there are effects such as shortening combustion time by gasification, and the combustible C can be effectively used and the NOx concentration in the cement kiln exhaust gas can be reduced while maintaining the stable operations of the treatment apparatus 1 and the cement burning device 10.

[0034] The configuration of the mixer 3 is not limited to the above, and if the combustible C can be mixed with the drawn preheated raw material R2 and gasified, and if water is further added to carry out water gas shift reaction, it can also be adopted in other types of devices.

DESCRIPTION OF THE REFERENCE NUMERALS

[0035] 1 combustible treatment apparatus [0036] 2 hopper [0037] 3 mixer [0038] 4 shut damper [0039] 5 feeder [0040] 6 exhaust gas duct [0041] 10 cement burning device [0042] 11 preheater [0043] 12 calciner [0044] 13 cement kiln [0045] 14 clinker cooler [0046] 15 main burner