EP0417288B1

EP0417288B1 - Drying and combustion apparatus of high moisture content solid inflammable matters

Info

Publication number: EP0417288B1
Application number: EP89911098A
Authority: EP
Inventors: Takashi 10-30 Wakabayashi Kikuchi; Shoji 105-1 Aza-Shinkawamukai Sakurai; Ikurou 2-16 Nishitaga 3-Chome Shisido; Touru 8-8 Kongou-Zawa Taihaku-Ku Yoshida; Hideo 6-5 Honcho Seki; Shinya 14-28 Kaigamori 3-Chome Aoba-Ku Watanabe
Original assignee: Takahashi Syokuhin Kogyo KK; Kameyama Tekkosho KK
Current assignee: MIYAGI KEN; Takahashi Syokuhin Kogyo KK; Kameyama Tekkosho KK
Priority date: 1989-03-30
Filing date: 1989-10-04
Publication date: 1994-06-15
Anticipated expiration: 2009-10-04
Also published as: KR920700378A; WO1990012250A1; EP0417288A1; DE68916245D1; KR940010659B1; DE68916245T2; EP0417288A4

Abstract

This invention relates to a drying and combustion apparatus of high moisture content solid inflammable matters which includes a hopper (20) for storing high moisture content solid inflammable matters, a dryer (1) for drying the high moisture content solid inflammable matters charged from the hopper (20) and an incinerator (23) for receiving the dried solid matters dried by the dryer (1) through a transfer pipe (22) and burning them, and which introduces the exhaust gas from the incinerator (23) into the dryer (1) and uses it as a drying gas. After the high moisture content solid inflammable matters are dried by the dryer (1), they are immediately transferred to and burnt in the incinerator (23). The exhaust gas from the incinerator (23) is used as the drying gas of the dryer (1).

Description

The present invention relates to an apparatus for drying and burning high-hydrous combustible solids or wet wastes, and more particularly to an improvement in or relating to a drying and burning system in which high-hydrous combustible solids such as bean-curd refuse, are put in and dried in an associated drier; the dried solids are brought and burnt in an associated furnace; and the hot waste gas is fed from the furnace to the drier to dry the wet waste.
As is well known, high-hydrous combustible solids or wet wastes such as bean-curd refuse, sewage or raw sewage are treated by dewatering, drying and burning. Specifically, wet waste is subjected to these treatments sequentially in a dehydrator, drier and furnace. These equipments were separate or independent from each other, not making up a composite or integrated system. In an attempt to meet energy-saving demand or reduce public nuisance the drier and furnace were combined to provide an integrated system.
Specifically, in such integrated system, the hot waste gas which is produced when drying the wet waste in the drier, is fed to the furnace to be burnt and deodorized. A part of so deodorized gas is fed to the drier, and is used as drying gas. This system constitutes a closed deodorizing system, and is advantageous from the energy saving point of view.
The conventional system, however, dries the wet waste in its drier, and burns the odor gas in its furnace for the sake of deodorizing rather than burning. Therefore, the conventional system requires another furnace for burning the deodorized material to ash. Accordingly, the whole size disadvantageously increases. The deodorizing furnace cannot be used to burn the dried waste because it is connected to the drier by a pipe whose size is large enough to allow the odor gas to pass to the furnace, preventing the dried waste from passing to the furnace.
It is known from JP-A-60-221613 to provide apparatus for drying and burning up high-hydrous combustible solids comprising: a hopper for receiving said high-hydrous combustible solids; a drier for drying said high-hydrous combustible solids with a heating gas circulating therein for forming dried combustible solids of low water content; a feeding means for feeding the dried combustible solids from said drier; a furnace connected to an end of said feeding means for receiving said dried combustible solids fed from said drier and for burning said dried combustible solids; and a combustion gas feedback passage disposed between said furnace and said drier for feeding back high temperature combustion exhaust gas from said furnace into said drier to be used as said heating gas. However, this document fails to teach any means for dealing with the offensive odor which is generated in the hopper.
Accordingly, the present invention is characterised in that air inlet means is incorporated in said hopper for introducing fresh air into said hopper for forming a mixture of a gas generated from said high hydrous combustible solids and air within said hopper, and in that a duct and a blower are provided for supplying the mixture as a carrier gas for said dried combustible solids to a solid-gas separator provided in said feeding means between said drier and said furnace.
An embodiment of the invention will now be described by way of example and with reference to the accompanying drawings, in which:-

Fig. 1 is a front view of the drier, partly broken to show internal parts of the drier;
Fig. 2 shows how circular wind motion is used for drying and fracturing;
Fig. 3 is a plane view of a perforated distribution plate;
Fig. 4 is a side view of the perforated distribution plate;
Fig. 5 is a plane view of a screw;
Fig. 6 is a side view of the screw;
Fig. 7 is a plane view of the blade;
Fig. 8 is a side view of the blade;
Fig. 9 is a plane view of an obstacle plate;
Fig. 10 is a side view of the obstacle plate;
Fig. 11 is a plane view of a fracturing blade;
Fig. 12 is a side view of the fracturing blade; and
Fig. 13 is a diagrammatic view of the drying-and-burning apparatus.

A cylindrical drier is indicated at 1, and this drier has a gas supplying vent 2 at its lower part; a dried waste exhaust opening 3 at its upper part; and a wet waste inlet opening 4 at a somewhat higher level than the intermediate level of the cylinder. These openings and vent are arranged longitudinally. Cylindrical drier 1 has a rotating shaft 5 along its longitudinal central axis, and electric motor 6 is used to rotate shaft 5. Perforated distribution plate 7 is laid adjacent to gas vent 2 at the bottom level of cylindrical drier 1 for distributing hot air. Screw 9 is fixed to rotating shaft 5 above perforated distribution plate 7. Screw 9 is adapted to be rotated by shaft 5. Blade 10 is provided at a higher level than screw 9. The screw 9 and blade 10 are arranged in such positions that dried waste may be brought upward by screw 9, and then may be made to fly by spiral wind motion, which is caused by blade 10.
An obstacle plate 11 is fixed to rotating shaft 5 at a higher level than blade 10. Obstacle plate 11 has small apertures 12 and pins 13 on its opposite surfaces. There is an annular gap between the circumference 16 of obstacle plate 11 and inside surface 17 of cylindrical drier 1. The gap is broad enough to allow pieces of dried waste solid to pass therethrough. Circular wind motion zone 18 is defined between obstacle plate 11 and blade 10.
In this particular embodiment there are another combination of obstacle plate 11 and blade 10 and another circular wind motion zone 18 at a higher level. Also, there is still another blade 10 at a still higher level. Inlet 4 for pieces of wet waste opens at the second circular wind motion zone 18, in which fracturing cross blade 14 having fracturing pins 15, is fixed to rotating shaft 5.
Now, referring to Fig. 13, the whole structure of drying-and-burning system is described below.
A hopper for containing wet waste is indicated at 20. Hopper 20 communicates with inlet 4 of drier 1 via screw conveyer 21. Exit 3 for discharging fragments of dried waste solid, communicates with furnace 23 via transportation conduit 22. More specifically, exit 3 communicates with the circular wind motion zone 25 of burner 24 in furnace 23 via transportation conduit 22. A solid-gas separator 26 is situated in transportation conduit 22. Specifically, solid-gas separator 26 has transportation conduit 22 at its upper level, and ejector 27 at its lower level. Ejector 27 is connected on its primary side to gas chamber 29, which is provided to side wall 28 of solid-gas separator 26, and ejector 27 is connected on its secondary side to the circular wind motion zone 25 of furnace 23.
Exhaust duct 31 extends from the upper part of the separating space 30 to the funnel-shaped solid-gas separator 26, thus permitting ejection of the gas from solid-gas separator 26 through cyclone 32, drawing fan 33 and exhaust duct 34. Dust box 35 is attached to the bottom of cyclone 32.
Hopper 20 is designed to contain high-hydrous combustible solids or wet waste such as bean-curd refuse, and it has inlet 35' for wet waste on its ceiling, and air inlet 36 on its side. An outlet 37 of hopper 20 is connected to inlet 40 of solid-gas separator 26 via air duct 39, which has a blower 38.
Wastegas outlet 41 of furnace 23 is connected to gas inlet 2 of drier 1 by wastegas return tube 42. Air duct 39 has a secondary air inlet tube 44 extending therefrom in the form of branch 43 downstream of blower 38, and connected to secondary air nozzle 45, which opens in combustion chamber 53. This combustion chamber 53 has a steam jacket 46 surrounding therearound, and water supply tank 48 having water softener 47 associated therewith, is connected to steam jacket 46 by water supply tube 49. The steam generated by steam jacket 46 may be used in producing related products. Wasteoil tank 51 is connected to burner 24 by wasteoil supply pipe 52.
The operation of the drying-and-burning system is described below.
High-hydrous combustible solids or wet wastes such as bean-curd refuse are put in hopper 20 from its inlet 35'. Then, wet waste is transported to inlet 4 of drier 1 by screw conveyor 21, and bulks of wet waste are thrown in drier 1 where they are broken into fragments by pins 15 of fracturing blade 14. The fragments of wet waste fall downward. In the course of descent by gravity the fragments of wet waste are struck and sprung upwards by rotating blade 10 on the second stage. While this takes place, the fragments of wet waste are brought in counter contact with rising flow of hot gas, thereby expediting the drying of wet waste. At the outset the fragments of wet waste have relatively high water content, and therefore they are relatively heavy. Thus, they are likely to fall on obstacle plate 11 as indicated by arrows A in Fig. 2 instead of being carried upwards by the rising gas. Rotating obstacle plate 11 has pins 13 thereon, and falling fragments are struck and sprung as indicated by arrow B in Fig. 2 so that they are struck against the inside surface 17 of drier 1, and they fall down along the inside surface 17 of drier 1 in the annular space between the circumference 16 of rotating blade 11 and the inside surface 17 of drier 1. During this process fragments of waste are in contact with hot wind, and accordingly they are being dried all the time. Finally, they fall on rotating screw 9, and then they are sprung up and carried upwards by rising gas. Thanks to rotating screw 9, gas supply inlet 2 and the apertures of distribution plate 7 cannot be blocked with fragments.
As indicated by arrow E in Fig. 2, fragments of waste are transferred to rotating blade 10, and as indicated by arrow F in Fig. 2, again they are sprung up by rotating blade 10. Then, smaller fragments of waste are carried upwards by circular wind motion, which is caused by rotating blade 10. During the process described so far fragment size is reduced gradually, and accordingly the proportionate surface area of each fragment increases, thus increasing the efficiency with which fragments of waste are brought in contact with gas. Also, as indicated by arrow G, fragments of waste are struck and sprung against the inner surface 17 of drier 1 by pins 13 on the lower surface of obstacle plate 11. Again, fragments of waste are broken and reduced in size. Then, they fall down along the inner surface 17 of drier 1.
Thus, pieces of wet waste material are brought by circular wind motion in zone 18 as indicated by arrows C-D-E-F-G-C until they are broken to small fragments, accordingly increasing the proportionate surface area of each fragment and expediting the drying of wet waste. Particles of dried solid are carried by hot wind which blows upwards from the apertures 12 of obstacle plate 11. In this particular embodiment particles of dried solid are subjected to the same treatment in circular wind motion zone 18 at the second stage, where solid particles are reduced in size, and dried even more. In this second stage the temperature of heated gas lowers somewhat, and the heated gas comes to contain water. Therefore, heat and water will be deprived with an extremely high efficiency.
Dried particles are struck and strung by final blade 10, and are carried away by hot air, leaving exhaust outlet 3.
When blower 38 is driven, air is supplied to the solid-gas separating space 40 of solid-gas separator 26 via outlet 37 of hopper 20 and air duct 39, thus collecting the odor from the inside of hopper 20.
The supplying of air to solid-gas separator permits separation of dried particles into solid and gas, and solid particles are reduced in size. The gas is discharged through air duct 31, cyclone 32 and exhaust duct 34. On the other hand, a part of supplied air is led to ejector 27 via air chamber 29, and pulverized solid is drawn and brought to circular wind motion zone 25 of furnace 23, where it is burnt by burner 24. The pulverized solid can be burnt well because of its minute particle size. This combustion is effected by using the air which carries the pulverized solid. In addition the combustion uses the secondary air which is drawn into combustion chamber 53 through secondary air supply conduit 44 branching downstream of blower 38.
Dried particles are burnt there, and the waste gas flows back to gas inlet 2 of drier 1 via gas return pipe 42 to be used in the drying process.
As may be understood from the above, in the drying-and-burning system according to the present invention the wet waste is dried in drier 1, and then the dried solid is brought to furnace 23, where it is burnt. This permits reduction of the size of the wet waste disposing system. Also, the waste gas from furnace 23 is made to return to drier 1 to be used as drying gas, and accordingly energy is saved. A single blower 38 is used to effect transportation of waste solid from drier 1 to furnace 23, reduction of dried waste solid in size, supply of air for combustion and collection of the odor from the wet waste in hopper 20.

Claims

Apparatus for drying and burning up high-hydrous combustible solids comprising: a hopper (20) for receiving said high-hydrous combustible solids; a drier (1) for drying said high-hydrous combustible solids with a heating gas circulating therein for forming dried combustible solids of low water content; a feeding means (22) for feeding the dried combustible solids from said drier; a furnace (23) connected to an end of said feeding means (22) for receiving said dried combustible solids fed from said drier and for burning said dried combustible solids; and a combustion gas feedback passage (42) disposed between said furnace (23) and said drier (1) for feeding back high temperature combustion exhaust gas from said furnace (23) into said drier (1) to be used as said heating gas;
characterised in that air inlet means (36) is incorporated in said hopper for introducing fresh air into said hopper (20) for forming a mixture of a gas generated from said high hydrous combustible solids and air within said hopper (20), and in that a duct (39) and a blower (38) are provided for supplying the mixture as a carrier gas for said dried combustible solids to a solid-gas separator (26) provided in said feeding means (22) between said drier (1) and said furnace (23).
Apparatus according to claim 1, wherein an ejector (27) is provided at the bottom of said solid-gas separator (26), into which ejector (27) the air and gas mixture is allowed to flow, making use of ejector effect to transport the separated solid to said furnace (23) and making use of the air carrying the separated solid as combustion air in said furnace (23).
Apparatus according to claim 1 or 2, wherein an exhaust tube (31), cyclone (32) and exhaust duct (34) are connected to said solid-gas separator (26).
Apparatus according to claim 1, 2 or 3, wherein said air duct (39) is divided into two branches downstream of said blower (38), one branch being connected to said solid-gas separator (26) and the other branch being connected to said furnace (23) to supply secondary air.
Apparatus according to any preceding claim, wherein said furnace (23) has a steam jacket (46) around its combustion chamber (53), the steam generated by said steam jacket (46) being used in producing a product.