US3585946A

US3585946A - Incinerator air supply and loading means

Info

Publication number: US3585946A
Application number: US866710A
Authority: US
Inventors: Ervin L Dahlund
Original assignee: US Department of Navy
Current assignee: US Department of Navy
Priority date: 1969-10-15
Filing date: 1969-10-15
Publication date: 1971-06-22
Anticipated expiration: 1988-06-22

Abstract

An incinerator capable of burning a large volume of all types of combustible rubbish and waste material within a combustion chamber at a pressure slightly below atmospheric thereby lowering exhaust stack temperatures and effectively reducing air pollution to a minimum.

Description

United States Patent Erwin L. Dahluad Long Beach, Calit.

Oct. 15, 1969 June 22, 1971 The United States of America as represented by the Secretary of the Navy Inventor Appl. No. Filed Patented Assignec INCINERATOR AIR SUPPLY AND LOADING MEANS 1 CIIImZDrawing Figs.

u.s.c1 110/8 R, 110/160 1111. c1 r23; s/os Field 01m 110/1, 8, 1a, 160

[56] References Cited UNITED STATES PATENTS 2,015,052 9/1935 Hartley 110/8 2,294,242 8/ 1942 Rohrer 1 10/7 2,397,870 4/1946 Kneags, Jr. 110/160 2,929,342 3/ 1960 Young 1 10/8 2,961,977 ll/1960 Coleman 1 10/8 Primary Examiner-Kenneth W. Sprague Attorneys-L. A. Miller, Q. E. Hodges, A. Sopp and W. F.

McCarthy ABSTRACT: An incinerator capable of burning a large volume of all types of combustible rubbish and waste material within a combustion chamber at a pressure slightly below atmospheric thereby lowering exhaust stack temperatures and effectively reducing air pollution to a minimum.

MOTOR PATENTED JUN22 19H INVENTOR. ERV/N L. DAHLUND w-f .h

A TTORNEYS INCINERATOR AIR SUPPLY AND LOADING MEANS The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

BACKGROUND OF THE INVENTION The present invention relates broadly to incinerators and particularly to incinerators adapted to be used on board ships for the purpose of treating sewage, rubbish, and other waste products.

In general, conventional incinerators are designed to burn waste at the bottom of a waste holding chamber. The gases resulting from the burning flow upwardly through the added waste and subsequently out through an exhaust stack. In such conventional incinerators the entire waste is eventually burning and the resulting effect is that a considerable amount of smoke and ashes are produced along with other malodorous and high temperature gases.

The high concentration of smoke and other obnoxious matter discharged through the stack combined with the high internal temperatures of the conventional incinerator quite often creates a breakdown in the stack structure and increases the hazard of fire within the stack. To combat these particular problems, special refractory stack liners had to be included to withstand the high temperatures. Moreover, additional burning zones in the stack had to be provided in an attempt to reduce the amount of unburned gas and ash that would be finally discharged into the atmosphere.

OBJECTS OF THE INVENTION An object of the present invention is to provide an incinerator which overcomes or considerably minimizes the foregoing disadvantages of a conventional incinerator.

Another object of the present invention is to provide air for the incineration of waste materials within a combustion chamber at a pressure slightly below atmospheric to eliminate the possibility of malodorous fumes escaping from the chamber into the surrounding atmosphere.

A still further object of the present invention is to reduce the exhaust temperature of the gases leaving the combustion chamber to a lower valve thus reducing the amount and/or quality of thermal insulation required to lower the exterior temperature of the exhaust stack.

Another important object of the present invention is to reduce the exhaust temperature of the gases in the exhaust stack so as to permit the use of common materials for stack construction.

A further object of the present invention is to provide a supply of combustion air independent of thermal gradients in the exhaust stack, thus permitting greater variations in the length of stack without affecting incinerator performance.

Still another object of the present invention is to provide for cooling the waste inlet passage to the incineration chamber to permit loading the incinerator without interposing a valve in the waste supply passage.

These and other objects and advantages of the present invention will appear more fully in the following specification, claims, and drawings in which:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional side elevation on a median line of an incinerator constructed according to the invention;

FIG. 2 is a section on the line 2-2 of FIG. 1.

DETAILED DESCRIPTION Referring in detail to the drawings, and in particular to FIG. I, combustible waste is dumped or otherwise placed into a collecting bin through a bin opening 12. The bin 10 is generally of such size as to permit the collection of sufficient waste to allow for possible continuous operation of the incinerator. Moreover, the collecting bin may include a sloping wall 14 to facilitate a downward movement of the waste material toward a feeding device comprising a helical screw conveyor 16.

The screw conveyor extends from a position at the bottom of bin 10 to a point above a waste passage 18 leading into a combustion chamber 20 and is driven by a motor 36. The conveyor may be so arranged that at least one full pitch of the screw is contained between the collecting bin 10 and the passage 18. Residual waste material remaining between the screw leads of the conveyor will provide an obstruction to air flow from the collecting bin downward through the passage 18. For reasons hereinafter to be described, excessive air flow to the combustion chamber from the collecting bin will disrupt the pressure balance within the incinerator.

In a like manner, residual waste remaining between leads of the screw conveyor in the area between the collecting bin and the waste passage will prevent the high temperature gases of combustion from igniting the waste material in the collecting bin. This construction therefor obviates the need for a valve in the waste passage and permits the addition of quantities of waste material to the collecting bin at any time. In particular, waste material may be added during those times when the combustion chamber is in full operation.

As waste material is deposited in the combustion chamber, it is first dried by heat supplied by the oil burner 22. Combustion air for the oil burner is provided through an opening or openings 24 located in the manner shown in FIG. 1.

Subsequent to a short drying period, the waste material ignites and burns without additional heat being supplied from the oil burner.

Suitable controls (not shown) shut off the supply of fuel to the oil burner at this stage of the process.

Exhaust gases resultingfrom the burning waste are removed from the combustion chamber by an eductor arrangement.

An eductor nozzle 26 is supplied with high-pressure air from a compressor 28. The high velocity of the air issuing from the nozzle 26 into a reduced diameter section 30 of exhaust stack 32 not only removes the exhaust gases from the combustion chamber but also produces an extremely low-pressure condition within the chamber.

Since the pressure within the combustion chamber is low as compared with the atmospheric pressure existing outside of the incinerator air is therefore forced into the reduced pressure zone within the incinerator through the opening 24 thereby increasing the efficiency of the combustion process.

Maintaining the pressure within the incinerator at a lower value than that of the surrounding atmosphere also prevents the escape from the incinerator of any noxious odors resulting from the combustion of the waste materials.

Gas temperatures at the stack entrance 34 are of a sufficiently high value to destroy all odors in the gases issuing from the stack 32.

More specifically, the temperatures at the stack entrance 34 will range from l,200 F. to 2,000 F. This range of high temperatures makes it necessary to use temperature resistant materials for the lower portion of the exhaust stack from the entrance 34 through to the reduced section 30.

Conventional thermal materials, capable of withstanding high temperatures, must be used to cover the area of the lower stack portion, as described above, for the purpose of protecting personnel who may unintentionally come into contact with this area of the incinerator.

Above the reduced section 30, however, the high-pressure air issuing from the nozzle 26 dilutes the exhaust and reduces the gas temperature substantially so that the portion of the stack above the reduced diameter section may be made of conventional low cost material such as mild steel. Furthermore, the thermal insulation that would be required in the stack above the reduced diameter section is also less expensive and of a lesser thickness than is usually required in conventional exhaust stack constructions.

The inlet 38 of the compressor 28 may be connected to spaces within the incinerator wherein ventilation is necessary or desirablejlFor example, as shown in H6. 1, a pipe 40 is connected at 42 to the collecting bin and the air being drawn in through the opening 12 will therefore provide ventilation for the bin and prevent odors from escaping back into the atmosphere.

In order to maintain a constant pressure in the combustion chamber and to assure a reasonably constant flow of combustion air through the opening 24, a draft regulator 44 is provided in a draft regulator duct 46. The draft duct communicates with the exhaust stack in the proximity of the stack entrance 34. The draft regulator is of conventional design and comprises a freely pivoted and weighted flap member which will be automatically opened in varying degrees as the air pressure in the combustion chamber is decreased below a predetermined level.

The driving energy of the high-pressure air issuing from the nozzle 26 is sufficient to cause a continuous and an appreciable air flow through the passage 46. The waste passage 118 into the combustion chamber is so located in the air passage 46 that air moving through the air passage will flow around and cool the waste passage.

Cooling fins 48 as shown in FIGS. 1 and 2 may be applied to the exterior of the waste passage 1% to assist in the transfer of heat which might be conducted up the waste passage walls 49 from the combustion chamber.

.Since the waste passage 18 is cooled, moist waste materials may be exposed to the high temperature gases of combustion without the excessive drying or caking which usually occurs in conventional incinerators.

The objects and advantages of the present invention have been fully and effectively accomplished by the incinerator described above and illustrated in the drawings. It will be realized that various changes may be made to the specific embodiment shown and described without departing from the principles and spirit of the present invention.

What I claim is:

1. ln an incinerator for disposing of combustible waste material having:

an incinerator body including a combustion chamber, a

waste inlet for receiving waste material, heating means for initiating combustion of said material, and an outlet for permitting various gases of combustion to be extracted, the improvement comprising: a collecting bin for receiving and storing combustible waste material; a

feeding means for feeding portions of said stored waste material from said bin to a waste passage which is externally cooled by forced air; said waste passage being disposed above the waste inlet of said chamber whereby said portions are conducted through said passage and into said chamber; and r eductor means disposed at said combustion camber outlet for extracting gases of combustion.

2. The incinerator of claim ll further comprising:

an air intake opening in said combustion chamber disposed adjacent said heating means and for providing a source of combustion air for said heating means.

3. The incinerator of claim 1 wherein the feeding means further comprises a helical conveyor member and motor means for driving said conveyor.

4. The incinerator of claim 1 wherein the eductor means further comprises:

an exhaust stack connected to said combustion chamber outlet;

a nozzle disposed in said stack at a position adjacent said combustion chamber outlet; and

a compressor for supplying high-pressure air to said nozzle,

whereby air under pressure is directed up said stack away from said combustion chamber.

5. The incinerator as described in claim 4 wherein the stack portion containing said nozzle is of a redaced diameter.

6. The incinerator as described in claim 5 wherein said exhaust stack includes a draft regulator located between said reduced diameter portion and said combustion chamber outlet whereby the air pressure in the combustion chamber can be maintained at a predetermined level.

7. The incinerator as described in claim 6 wherein air passing through said draft regulator externally cools said waste passage.

Claims

1. In an incinerator for disposing of combustible waste material having: an incinerator body including a combustion chamber, a waste inlet for receiving waste material, heating means for initiating combustion of said material, and an outlet for permitting various gases of combustion to be extracted, the improvement comprising: a collecting bin for receiving and storing combustible waste material; feeding means for feeding portions of said stored waste material from said bin to a waste passage which is externally cooled by forced air; said waste passage being disposed above the waste inlet of said chamber whereby said portions are conducted through said passage and into said chamber; and eductor means disposed at said combustion camber outlet for extracting gases of combustion.

2. The incinerator of claim 1 further comprising: an air intake opening in said combustion chamber disposed adjacent said heating means and for providing a source of combustion air for said heating means.

4. The incinerator of claim 1 wherein the eductor means further comprises: an exhaust stack connected to said combustion chamber outlet; a nozzle disposed in said stack at a position adjacent said combustion chAmber outlet; and a compressor for supplying high-pressure air to said nozzle, whereby air under pressure is directed up said stack away from said combustion chamber.

5. The incinerator as described in claim 4 wherein the stack portion containing said nozzle is of a reduced diameter.