WO2004070300A1

WO2004070300A1 - Duplex rotary kiln and mobile waste treatment system comprising the same

Info

Publication number: WO2004070300A1
Application number: PCT/KR2004/000217
Authority: WO
Inventors: Young-Ill Hwang; Kook-Chan Ahn
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-02-05
Filing date: 2004-02-05
Publication date: 2004-08-19
Anticipated expiration: 2005-08-05

Abstract

A duplex rotary kiln, for use in separately drying or incinerating wastes according to sizes to increase treatment efficiencies of the wastes, includes an outer rotary kiln having a cylindrical body, an inner rotary kiln having a cylindrical body sized differently from that of the outer rotary kiln and formed of meshes to transfer wastes smaller than predetermined sizes to the outer rotary kiln, and spiral blades attached to internal walls of the outer and inner rotary kilns to transfer the wastes. Further, a mobile treatment system using the duplex rotary kiln is provided for onsite recycling of wastes, such as waste shells, composed of a waste-feeding unit, a rotary-type sorting unit, a duplex rotary kiln, a three-staged air cooling unit, a multi-staged pressure sorting unit, and a storing hopper, sequentially connected on a base frame to be mounted to movable vehicles.

Description

DUPLEX ROTARY KILN AND MOBILE WASTE TREATMENT SYSTEM

COMPRISING THE SAME

Technical Field

The present invention relates to a duplex rotary kiln having high treatment efficiencies of wastes, by transferring wastes of small sizes into an inner rotary kiln of the duplex rotary kiln and wastes of large sizes into an outer rotary kiln thereof to separately dry or incinerate the wastes according to sizes, and a mobile waste treatment system including the duplex rotary kiln, for use in onsite recycling of wastes, for example, waste shells .

Background Art

Typically, there have been used rotary kilns to dry or incinerate waste solids, in which the rotary kiln is classified into hot air type and direct-fired burner type. As such, quantities of fuel required to dry the waste solids, and drying efficiencies of the waste solids, depend on temperatures of hot air, and fire directions and jetting radii of the burner, in the kiln.

However, the conventional rotary kiln using direct- fired burner is disadvantageous in terms of low heat efficiencies . This is because the waste solids are dried by radiant heat in the kiln while being exposed to direct heat of the burner for a short time, upon jetting fire of the burner to be parallel with the kiln-disposed direction or toward a lower portion of the kiln.

Therefore, as the jetting radius of the burner increases, the radiant heat has higher temperatures and f el consumption increases . When waste solids having different sizes are dried, the temperature of the radiant heat in the kiln acts as an important factor determining the dry state of the waste solids . Accordingly, with the aim of drying the waste solids, there are proposed methods of increasing dry temperatures or extending dry time in the kiln, that is, a long kiln is manufactured to generate sufficient radiant heat. However, these methods suffer from high fuel consumption, thus negating economic benefits. Further, the conventional rotary kiln has a large volume and is long, and thus, equipment costs relatively increase and heat efficiency decreases. On the other hand, a recycling method of waste solids includes a series of processes of firstly sorting, drying, cooling, crushing by use of a hammer crusher, secondly sorting through a vibrating sieve, firstly transferring by- use of a conveyer or bucket elevator, secondly transferring into a storage bath, and packaging. However, the above recycling method suffers from high costs for waste disposal, fuel, transfer equipment and entire equipment. After all, price competitiveness of recycled products decreases, which negatively affects sales, and thus, recycling plants become in the state of discontinuance or shutdown.

Particularly, in cases where waste shells are treated to prepare feedstuffs or manures by use of treatment equipment provided in the plant site for mass production, the equipment may be blocked, attributable to properties of shell particles, upon sorting the waste shells into feedstuff usage and manure usage according to particle sizes. Therefore, a crusher and a sieve are additionally mounted in a double or triple type, and the treatment equipment becomes large-sized and requires high maintenance costs .

Eventually, such waste shells may be illegally buried in landfills or dropped in the ocean to reduce the treatment costs thereof. Further, since there are proposed no other alternatives, in addition to conventional treatment methods, the above illegal methods have been performed with connivance, hence resulting in increased environmental pollution.

Disclosure of the Invention

Accordingly, the present invention has been made keeping in mind the above problems occurring in the related art, and an object of the present invention is to provide a duplex rotary kiln including inner and outer rotary kilns, characterized in that wastes are separately transferred according to sizes thereof, whereby wastes of small sizes and wastes of large sizes are dried or incinerated in the outer rotary kiln and the inner rotary kiln, respectively, thus drastically increasing treatment efficiencies of the wastes . Another object of the present invention is to provide a mobile waste treatment system including the duplex rotary kiln, for use in onsite recycling of waste shells, thereby decreasing waste-transferring costs, sizes and weights of equipment, and maintenance costs, while causing no environmental pollution.

To achieve the above objects, the present invention provides a duplex rotary kiln, including a duplex rotary kiln body, a supporting part to rotatably support the duplex rotary kiln body, a driving means for rotatably driving the duplex rotary kiln body, a burner to heat an inner rotary kiln of the duplex rotary kiln body, a feeding part to feed waste solids into the duplex rotary kiln body, and a discharging part provided at an opposite end of the feeding part, wherein the duplex rotary kiln body has an outer rotary kiln having a cylindrical body, an inner rotary kiln having a cylindrical body sized differently from that of the outer rotary kiln and formed of meshes to transfer waste solids smaller than predetermined sizes into the outer rotary kiln, and spiral blades attached to internal walls of the outer and inner rotary kilns to transfer the waste solids .

Brief Description of the Drawings

The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a perspective view showing a duplex rotary kiln according to the present invention;

FIG. 2 is a schematic view showing structures of inner and outer rotary kilns of the duplex rotary kiln according to the present invention;

FIG. 3 is a view showing a transferring process of waste solids by the duplex rotary kiln according to the present invention; and

FIG. 4 is a schematic view showing a mobile waste treatment system including the duplex rotary kiln according to the present invention; and

FIG. 5 is a view showing a treating process of waste solids by the mobile waste treatment system including the duplex rotary kiln according to the present invention; . Best Mode for Carrying Out the Invention

Reference should now be made to the drawings, in which the same reference numerals are used throughout the different drawings to designate the same or similar components .

FIG. 1 is a perspective view showing a duplex rotary kiln according to the present invention. FIG. 2 is a view showing structures of inner and outer rotary kilns of the duplex rotary kiln according to the present invention, and FIG. 3 is a view showing a state of waste solids being transferred by the duplex rotary kiln according to the present invention.

As shown in the above drawings, the duplex rotary kiln 10 of the present invention includes a duplex rotary kiln body 11, a supporting part to rotatably support the rotary kiln body 11, a driving means for rotatably driving the rotary kiln body 11, a burner 19 to heat an inner rotary kiln 12 of the rotary kiln body 11, and a feeding part to feed waste solids into the rotary kiln body 11. The duplex rotary kiln body 11 has inner and outer rotary kilns 12 and 13 which are concentrically arranged, each of which is formed in a cylinder shape. Further, the inner rotary kiln 12 has a smaller diameter than that of the outer rotary kiln 13 to form a predetermined space therebetween. Therefore, waste solids of small sizes passed through meshes of the inner rotary kiln are transferred into the above space defined by the inner and outer rotary kilns 12 and 13. In addition, spiral blades 14 and 14', serving to transfer the waste solids, are attached to internal walls of the inner and outer rotary kilns 12 and 13. As such, the inner rotary kiln 12 is preferably formed with a highly heat-conductive material, for example, stainless steel . Represented by the supporting part, a pair of supporting rollers 15 are mounted at both sides of a lower portion of the rotary kiln body 11, and thus, functions to allow the rotary kiln body 11 to be rotated while enduring a load of the rotary kiln body 11. The driving means includes a ring gear 16 mounted along an outer surface of the rotary kiln body 11, a driving gear engaged with the ring gear 16, and a driving motor 18 to rotate the driving gear 17. Alternatively, sprockets may be mounted to the outer surface of the rotary kiln body 11 and the shaft of the driving motor, respectively, and then connected to each other via chains to allow the rotary kiln body 11 to be rotatably driven.

Also, the burner 19 is installed at one end of the rotary kiln body 11 to heat an inside of the inner rotary kiln 12. The feeding part acts to feed the waste solids into the inner rotary kiln 12 of the rotary kiln body 11 by means of a transporting device, such as a chute using natural dropping or a screw conveyer.

Although being not illustrated in the above drawings, a discharging part and an exhaust port are opposite to the feeding part for the waste solids, in which the discharging part is used to discharge dried waste solids or incinerated ashes and the exhaust port is used to exhaust a combustion gas.

Meanwhile, as for operation of the duplex rotary kiln of the present invention, when the waste solids are fed into the inner rotary kiln 12 of the rotary kiln body 11 through the feeding part, they are transferred by means of the spiral blades 14 and 14' attached to the internal walls of the inner and outer rotary kilns while the rotary kiln body 11 is rotated through the driving motor 18 and the gears 16 and 17.

Upon transferring, since the inner rotary kiln 12 is formed of meshes, waste solids having small sizes are removed from the inner rotary kiln 12 and are then transferred into the outer rotary kiln 13.

In such cases, the inside of the inner rotary kiln 12 is heated at high temperatures by means of the burner 19. The waste solids of large sizes transferred into the inner rotary kiln 12, which require a long dry time, are dried or incinerated by direct heat of the burner 19. In contrast, the waste solids of small sizes transferred into the outer rotary kiln 13, which require a relative short dry time, are dried or incinerated by radiant heat emitted from the inner rotary kiln 12. Thus, the duplex rotary kiln of the present invention is advantageous in terms of remarkably increased drying efficiencies of waste solids, and also, uniform drying process, regardless of the sizes of the waste solids.

Moreover, the inner and outer rotary kilns 12 and 13 of the duplex rotary kiln body can be maintained at predetermined temperatures by each other. That is, the inner rotary kiln 12 can be maintained at a predetermined temperature by the outer rotary kiln 13 heated by the radiant heat, while the outer rotary kiln 13 can be maintained at a predetermined temperature by the heat of the inner rotary kiln 12.

The waste solids transferred by the above operation are dried or incinerated while passing through the inner and outer rotary kilns 12 and 13 of the duplex rotary kiln body, and are then discharged through the discharging part. In addition, gas generated upon drying or incinerating is exhausted by the exhaust port, or is completely combusted through a second combustion furnace and then exhausted. Further, waste heat emitted through the exhaust port is recovered and then introduced into an air feeder of the feeding part, whereby fuel can be saved and ashes can be prevented from emission. Turning now to FIG. 4, there is illustrated a view showing a structure of a mobile waste treatment system including the duplex rotary kiln according to the present invention. Also, FIG. 5 is a view showing a treating process by the mobile waste treatment system including the duplex rotary kiln according to the present invention.

As illustrated in the above drawings, the mobile waste treatment system including the duplex rotary kiln 10 has a feeding unit 20, a rotary-type sorting unit 30 having a low load, a duplex rotary kiln 10 having high efficiency, a three-staged air cooling unit 40 to decrease the generation of ashes, a crushing unit 50, a sorting unit 30 using multi-staged pressure by a blower, a storing hopper, and a packaging unit, all of which are sequentially connected by means of transfer devices . The above listed units are disposed on a base frame 70 so as to be mounted to movable vehicles, in which sizes of the vehicles become different according to treating quantities of the waste treatment system. To recycle waste solids, predetermined amounts of waste solids are fed into the waste treatment system through the feeding unit 20, among which large impurities or coating string are filtered off by use of the sorting unit 30. Like this, the sorted waste solids are discharged in quantitative amounts.

The waste solids sorted and then quantitatively discharged, for example, waste shells, are dried by use of the duplex rotary kiln 10 of the present invention. Specifically, waste solids having small sizes are dried by direct heat by a burner 19 in an inner rotary kiln 12 of a duplex rotary kiln body 11 constituting the duplex rotary kiln of the present invention. On the other hand, waste solids having large sizes transferred from the inner rotary kiln 12 into an outer rotary kiln 13 are dried by radiant heat of the inner rotary kiln. Thereby, while high drying efficiencies are achieved by the duplex rotary kiln of the present invention, alkaline components to be floated are obtained

Thereafter, the dried waste shells are cooled by means of the cooling unit 40. In this case, the reason why the cooling process is required is that the waste shells are prevented from agglomeration due to water absorption at the following crushing process. The cooling unit 40 is preferably exemplified by a three-staged rotary cooling unit 40. Subsequently, the cooled waste shells are crushed by the crushing unit 50, controlled to powder sizes of 5-10 mm using a sieve, and then transferred to the sorting unit 60.

The crushed powders are sorted twice by the blower while passing through the sieve of the sorting unit 60, and hence, discharged and then packaged.

The waste treatment system of the present invention, which is manufactured to have a small size and a low weight, compared to conventional huge treatment equipment, can be mounted to 5-ton freight cars or special cars. Consequently, by use of the inventive waste treatment system, the waste shells can be treated at 3 ton per time and recycled at 1 ton per time, with 33% of production yield. Further, calcium can be obtained in the amount of 40% or more, along with 45% alkaline calcium for use in agricultures or industries .

Industrial Applicability

As described above, the present invention provides a duplex rotary kiln and a mobile waste treatment system including the same. The duplex rotary kiln of the present invention is characterized in that waste solids are separately dried according to sizes thereof. That is, waste solids of large sizes requiring a long dry time are transferred into an inner rotary kiln of the duplex rotary kiln, and then dried by direct heat of a burner, while waste solids of small sizes are transferred into an outer rotary kiln from the inner rotary kiln, and then dried by radiant heat, thereby increasing drying efficiencies. Thereby, the inventive duplex rotary kiln is advantageous in terms of low fuel costs, and can be small-sized, on account of improvement of performance thereof, thus generating economic benefits.

Further, the waste treatment system including the duplex rotary kiln can be mounted to movable freight cars or special cars. Thus, the waste solids, in particular, waste shells, can be onsite treated without the need of a separate transferring process, resulting in reduced treatment costs. Moreover, the above waste treatment system can be designed to be small and light while exhibiting high treatment performance, and hence, can be economically manufactured, and maintenance costs thereof can be saved. In addition, treatment of the waste solids using the inventive waste treatment system can be actively performed, instead of ocean dumping or burying treatment which has been conventionally carried out, and therefore, it is possible to treat waste solids not causing pollution.

Although the preferred embodiment of the present invention has been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims

1. A duplex rotary kiln, comprising: a duplex rotary kiln body; a supporting part to rotatably support the duplex rotary kiln body; a driving means for rotatably driving the duplex rotary kiln body; a burner to heat an inner rotary kiln of the duplex rotary kiln body; a feeding part to feed waste solids into the duplex rotary kiln body; and a discharging part provided at an opposite end of the feeding part, wherein the duplex rotary kiln body includes an outer rotary kiln having a cylindrical body, an inner rotary kiln having a cylindrical body sized differently from that of the outer rotary kiln and formed of meshes to transfer waste solids smaller than predetermined sizes into the outer rotary kiln, and spiral blades attached to internal walls of the outer and inner rotary kilns to transfer the waste solids .

2. A mobile waste treatment system comprising the duplex rotary kiln of claim 1, including: a waste-feeding unit; a rotary-type sorting unit having a low load; a duplex rotary kiln having high efficiency; a three-staged air cooling unit to reduce generation of ashes; a multi-staged pressure sorting unit using a blower; and a storing hopper, sequentially connected by means of transfer devices and disposed on a base frame so as to be mounted to movable vehicles