US3577939A

US3577939A - Incinerators

Info

Publication number: US3577939A
Application number: US822977A
Authority: US
Inventors: Duncan Ronald Muirhead
Original assignee: Rose Downs and Thompson Ltd
Current assignee: SUPERBURN SYSTEMS Ltd; Rose Downs and Thompson Ltd
Priority date: 1968-05-10
Filing date: 1969-05-08
Publication date: 1971-05-11
Anticipated expiration: 1988-05-11
Also published as: GB1212887A

Abstract

In a method of disposing of town refuse, the refuse is burnt whilst supported in an incinerator by a fluidized bed of refractory granular material and the bed is separated from an outlet of the incinerator container by a mass of refractory granular material which is periodically fluidized to allow the noncombustible content of the refuse to pass therethrough and be removed from the incinerator through the outlet. The mass of refractory granular material may form an extension of the bed which supports the refuse whilst it is burnt with the mass of granular material positioned between the part of the bed which supports the refuse and an outlet from the incinerator container.

Description

References Cited UNITED STATES PATENTS United States Patent [72] Inventor Duncan Ronald Muirhead Narrow Lane, near Ferrby, England L. m e GST 7008 666 999 lll 2.18 l 0057 965 54,6, 217 01.9 3,4,3 333 .M .m L n m P m m l& 97 s 69n w1 w 9 9 nyym SWWR o. e N m e ,Wd ma@ P mm AFPA 11:1] |253 224-/ r..[[[

Primary Examiner--Kenneth W. Sprague Kingston-upon-Hull, Yorkshire, England rNcrNEruiroRs This invention relates to a method of disposing of town refuse by burning it in an incinerator and to incinerators suitable for burning town refuse.

Until recently town refuse has been disposed of mainly by tipping into worked-out quarries and mineshafts. As the number of sites suitable for tipping has gradually diminished and the quantity of refuse to be disposed of has increased, the disposal of town refuse has become an increasingly important problem to Local Authorities. The calorific value of town refuse has however increased due mainly to an increase in the use of disposable combustible materials for packaging purposes and a number of proposals have been put forward for burning the refuse in incinerators. Conventional incinerators usually have some form of travelling grate which supports the refuse and keeps it moving in the incinerator so that the combustible material can be completely burnt. Town refuse contains some noncombustible material and unless care is taken, this noncombustible material can quickly build up and clog the travelling grate and also prevent an adequate air supply from reaching the combustible material from beneath the grate.

According to the first aspect of the present invention in a method of disposing of town refuse, the refuse is deposited into an incinerator and the combustible content of the refuse is burnt whilst supported by a fluidized bed of refractory granular material, and a mass of refractory granular material separating said fluidized bed from an outlet of the container is periodically fluidized to allow the noncombustible content of the refuse to pass therethrough and be removed from said incinerator through said outlet.

The refractory granular material is conveniently fluidized by passing air therethrough.

When the mass of granular material is fluidized the noncombustible content of the refuse is flushed out through the outlet by the flow of said granular material therethrough. The mass of refractory granular material in the bed then has to be restored to its original mass by adding granular material into the incinerator.

According to a second aspect of the present invention an incinerator for burning town refuse comprises an elongate container arranged with its longitudinal axis substantially horizontal, said container defining a first opening at one end thereof through which town refuse is introducible into the container and defining a second opening at the other end thereof, a bed of granular refractory material in the container extending between said ends with the surface of the bed positioned below the first opening and above the second opening, means for passing a gaseous medium through a part of said bed extending from the end of the container adjacent to the first opening along the greater part of the length of the container to fluidize that part of the bed, and separate means for passing a gaseous medium through the remaining part of the bed to fluidize that part of the bed.

Since there are no moving parts in the incinerator which correspond to the travelling grate in a conventional incinerator, the noncombustible content of the refuse cannot clog the moving parts and when the noncombustible content of the refuse has built up in the incinerator the mass of refractory granular material is fluidized to flush out the noncombustible content from the container.

When the incinerator is in use, heat developed from the y burning refuse may be used to dry and burn slurries, for examl ple of sewage sludge, injected into the incinerator. Alternatively, or in addition, some of the heat developed in the incinerator may be absorbed by waste heat recovery equipment such as a boiler or heat exchanger.

The town refuse is deposited onto the bed the greater part of the length of which is fluidized and the combustible material in the refuse either forms part of and burns in the fluidized bed or floats on the surface ofthe bed while it burns. lf the combustible material burns while forming part of the bed, the `bed must be fluidized by an oxidizing gaseous medium such as air. Further air or oxygen may be provided above the surface of the bed. lf the combustible material is burnt while it floats on the surface of the bed, the bed is fluidized by a gaseous medium or steam and a further supply of oxidizing gaseous medium may have to be provided above the surface of the bed. Any part of the refuse which is not readily combustible eventually sinks through the bed and due to the action of the bed moves towards the end of the bed adjacent the nonfluidized mass of refractory granular material. This nonfluidized mass prevents the granular material which is fluidized from leaving the container through the outlet thereof. When it is desired to remove the noncombustible content of the refuse from the incinerator, the part of the `bed adjacent the outlet from the container is fluidized allowing the granular material forming at least that part of the bed to flow out through the outlet from the container bringing much of the noncombustible material with it.

After the noncombustible part of the refuse has been flushed out of the container it is necessary to add more granular material to the bed to restore it to its original depth and if desired the granular material and the noncombustible content of the refuse may pass onto a screw when it leaves the container so that the granular material passes through the screen and is collected and returned to the container at the end thereof to which the town refuse is added.

ln order that the invention may be more readily understood it will now be described, by way of example only, with reference to the accompanying drawing in which:

The FIGURE is a sectional side elevation of an incinerator in accordance with one embodiment of the invention.

An incinerator for burning town refuse comprises an elongate container 3l arranged with its longitudinal axis substantially horizontal and having a lining 32 of solid refractory material. Alternatively the walls can be constructed of forcecooled material. The base 33 of the container is apertured and below the base there are two hollow boxes k34 and 35 together extending the length of the container with the box 34 extending for the greater part of the length. The base 33 forms one wall of each box. At one end of the container there is an opening 36 through which town refuse is introduced into the incinerator and if desired the refuse may be shredded in a shredder 37 prior to being introduced into the container. A second opening 38 at the other end of the container is positioned adjacent the base thereof. The roof 39 of the container is inclined to the base so that the height of the container is a minimum at the end adjacent the opening 38 and the roof leads into a smoke stack 40 which may include a gas-cleaning system (not shown). A bed 4l of granular refractory material, such as sand, pulverized ash or alumina is supported on the base of the container and extends along the length thereof. The surface of the bed is below the level of the opening 36 and above the level of the opening 38. The part of the bed located above the box 34 is fluidized by passing a gaseous medium such as air into the container through theapertures in the base 33 from the box 34. The gaseous medium is supplied to the box through a pipe 42 and is controlled by a valve 43 lfitted in the pipe. Similarly the part of the bed located above the air box 35 is fluidized by a gaseous medium such as air or steam passed into the bed from the box 35 through the apertures in the base 33. The gaseous medium is supplied to the box 35 through a pipe 44 and is controlled by a valve 45.

To start the incinerator, town refuse is supplied to the container through the opening 36 and is supported on lthe surface of the bed of granular refractory material. A suitable fuel is introduced into the incinerator with the first load of refuse in order to ignite the refuse and once the granular refractory material is up to working temperature the combustible material in the refuse will ignite spontaneously as it falls onto the bed and the supply of fuel to the incinerator can be stopped. A regulatable supply of air to the incinerator to assist combustion enters the incinerator through a plurality of nozzles some of which are indicated by reference numeral 46. 'The part of the bed above the box 34 is fluidized and the combustible content of the refuse is burnt in the fluidized bed or floats on the surface of the bed while it burns. lf the fluidizng gas is oxidizing, little or no air may be supplied through the nozzles 46. The fiuidized part of the bed is in the main prevented from leaving the container through the outlet 38 by the part of the bed above the box 35 which is not fluidized and this part of the bed forms a dam which prevents the mass of fluidized material from flowing out of the container. The noncombustible content of the town refuse, will sink through the fiuidized bed and collect on the base 33 of the container. The action of the gaseous medium supplied to the bed through the box 34 causes the noncombustible refuse to pass along the container until it reaches the nonfiuidized part of the bed above the box 35.

Periodically it is necessary to remove the noncombustible part of the refuse and to this end the part of the bed which forms the dam is then fiuidized and a large part of the granular material flows out of the outlet 38 flushing out the noncombustible content of the refuse with it. The gaseous medium supplied to the box 35 is then cut off and the part of the bcd above the box 35 is then rendered nonfluidized and forms a dam which prevents further granular material from leaving the container.

The granular material and the noncombustible content of the refuse leaving the container through the opening 38 falls onto a screen 47 which permits the granular material to pass therethrough while retaining the noncombustible material. lt is necessary to keep the surface of the bed in the container at a substantially constant level above the base 33 and to this end it is necessary to introduce granular refractory material into the container through the opening 36 from time to time. When the screen 47 is employed the granular material pass therethrough can be collected and returned into the container through the opening 36.

Sewage sludge can be sprayed into the incinerator through a plurality of nozzles positioned above the surface of the fiuidized bed. Such nozzles are indicated by reference numeral 48. The heat from the burning town refuse in the incinerator dries out the sludge and the sludge is burnt in the incinerator.

l claim:

l. An incinerator for burning town refuse comprising an elongate container arranged with its longitudinal axis substantially horizontal, said container defining a first opening at one end thereof through which town refuse is introducible into the container and defining a second opening at the other end thereof, a bed of granular refractory material in the container extending between said ends with the surface of the bed positioned below the first opening and above the second opening, means for passing a gaseous medium through a part of said bed extending from the end of the container adjacent to the first opening along the greater part of the length of the container to fludize that part of the bed, and separate means for passing a gaseous medium through the remaining part of the bed to fiuidize that part of the bed.

2. An incinerator as claimed in claim l in which the base of the container is apertured and forms one wall of each of a pair of hollow boxes extending end-to-end beneath the base, with one box positioned beneath that part of the bed which extends along the greater part of the length of the container and the other box positioned beneath the remaining part of the bed, and separate means associated with each box for supplying gaseous medium thereto.

3. An incinerator as claimed in claim l in which said refractory granular material is alumina.

4. An incinerator as claimed in claim 1 in which means are provided for shredding the town refuse prior to it being introduced into the container through said first opening.

5. An incinerator as claimed in claim l having means supported by the container above the level of the surface of the bed for spraying sewage sludge into the incinerator to be burnt therein.

6. An incinerator as claimed in claim l having means supported by the container above the level of the surface of the bed for introducing oxidizing gas into the container.

7. An incinerator for burning town refuse comprising an elongate container arranged with its longitudinal axis substantially horizontal and having a substantially horizontal apertured base, a first opening in the container adjacent one end thereof and a second opening in the container wall at the opposite end thereof, said second opening extending to the base of the container,

said base forming one wall of each of a pair of hollow boxes extending end-to-end beneath the base with one of the boxes extending from the end of the container adjacent said first opening along the greater part of the length of the base,

separate means associated with each box for supplying air thereto and a bed of alumina in the container extending between said ends with the surface of the bed positioned below the first opening and above the second opening.

8. A method of disposing of refuse which comprises the steps of providing first and second masses of refractory granular material in an incinerator defining a first opening positioned above the surface of the first mass and a second opening positioned below the surface of the second mass, fluidizng the first mass of material by passing a gaseous medium therethrough, depositing refuse through the first opening into the incinerator and burning said refuse while supported by said fiuidized first mass, periodically fiuidizing the second mass of refractory granular material by passing a gaseous medium therethrough to allow the noncombustible content of the refuse to pass therethrough and removing the noncombustible content of said refuse through said second opening.

Claims

1. An incinerator for burning town refuse comprising an elongate container arrangeD with its longitudinal axis substantially horizontal, said container defining a first opening at one end thereof through which town refuse is introducible into the container and defining a second opening at the other end thereof, a bed of granular refractory material in the container extending between said ends with the surface of the bed positioned below the first opening and above the second opening, means for passing a gaseous medium through a part of said bed extending from the end of the container adjacent to the first opening along the greater part of the length of the container to fluidize that part of the bed, and separate means for passing a gaseous medium through the remaining part of the bed to fluidize that part of the bed.

2. An incinerator as claimed in claim 1 in which the base of the container is apertured and forms one wall of each of a pair of hollow boxes extending end-to-end beneath the base, with one box positioned beneath that part of the bed which extends along the greater part of the length of the container and the other box positioned beneath the remaining part of the bed, and separate means associated with each box for supplying gaseous medium thereto.

3. An incinerator as claimed in claim 1 in which said refractory granular material is alumina.

5. An incinerator as claimed in claim 1 having means supported by the container above the level of the surface of the bed for spraying sewage sludge into the incinerator to be burnt therein.

6. An incinerator as claimed in claim 1 having means supported by the container above the level of the surface of the bed for introducing oxidizing gas into the container.

7. An incinerator for burning town refuse comprising an elongate container arranged with its longitudinal axis substantially horizontal and having a substantially horizontal apertured base, a first opening in the container adjacent one end thereof and a second opening in the container wall at the opposite end thereof, said second opening extending to the base of the container, said base forming one wall of each of a pair of hollow boxes extending end-to-end beneath the base with one of the boxes extending from the end of the container adjacent said first opening along the greater part of the length of the base, separate means associated with each box for supplying air thereto and a bed of alumina in the container extending between said ends with the surface of the bed positioned below the first opening and above the second opening.

8. A method of disposing of refuse which comprises the steps of providing first and second masses of refractory granular material in an incinerator defining a first opening positioned above the surface of the first mass and a second opening positioned below the surface of the second mass, fluidizing the first mass of material by passing a gaseous medium therethrough, depositing refuse through the first opening into the incinerator and burning said refuse while supported by said fluidized first mass, periodically fluidizing the second mass of refractory granular material by passing a gaseous medium therethrough to allow the noncombustible content of the refuse to pass therethrough and removing the noncombustible content of said refuse through said second opening.