Title:
SYSTEM FOR CONTROLLING THE BURNING OR STOCK PILING OF REFUSE ACCORDING TO OPERATING CONDITIONS OF AN INCINERATOR
United States Patent 3702594


Abstract:
An automatic monitoring system for burning or stock piling refuse implemented by controlling the operation of an improved incinerator according to its operating conditions at any given point of time.



Inventors:
HOWES LESLIE D
Application Number:
05/181672
Publication Date:
11/14/1972
Filing Date:
09/20/1971
Assignee:
LESLIE D. HOWES
GARLAND STEEL CO.
Primary Class:
Other Classes:
110/186, 110/190, 110/192, 110/193, 110/257
International Classes:
F23D14/72; F23G5/32; F23G5/50; (IPC1-7): F23G5/12
Field of Search:
110/7R,8R,8C,18R
View Patent Images:
US Patent References:
3460489INCINERATOR1969-08-12Ehrenzeller et al.
3354847Incinerator1967-11-28Clement et al.
3286666Combustion apparatus1966-11-22Ohlssen
3225721Dumping refractory hearth furnace1965-12-28Rowley



Primary Examiner:
Sprague, Kenneth W.
Claims:
I claim

1. A refuse burner comprising:

2. The refuse burner set forth in claim 1 wherein:

3. The refuse burner set forth in claim 2 in further combination with a natural gas burner mounted in said conduit for igniting the refuse before it is injected into said combustion chamber.

4. The refuse burner set forth in claim 3 in further combination with pneumatic means for driving the refuse on a stream of air through said conduit.

5. The refuse burner set forth in claim 4 wherein said means comprises a blower.

6. A refuse burning system comprising:

7. The refuse burning system set forth in claim 6 in further combination with:

8. The refuse burning system set forth in claim 6 in further combination with:

9. The refuse burning system set forth in claim 6 in further combination with:

10. The refuse burning system set forth in claim 7 in further combination with:

11. The refuse burning system set forth in claim 8 in further combination with:

12. The refuse burning system set forth in claim 11 wherein said second sensor, upon sensing that gas under pressure flowing through said nozzle is not ignited, actuating said valve means to cause the refuse to flow through said discharge conduit.

13. The refuse burning system set forth in claim 12 in further combination with:

14. The refuse burning system set forth in claim 13 in further combination with:

Description:
BACKGROUND OF THE INVENTION

This invention is directed to the disposal of waste material of a combustible nature, and more particularly to a method and system for handling refuse of a varying amount through the burning or stock piling of it according to the momentary operating conditions of an associated incinerator.

1. Field of the Invention

This invention relates to the monitoring and regulating of an improved incinerator by the constant sensing of the operating conditions of the incinerator under conditions of varying refuse imput.

2. Description of the Prior Art

Disposal of waste materials of a combustible nature is a problem since land fill methods now used are expensive and burning structures now used do not provide complete combustion without the production of excessive soot and smoke. Waste disposal is particularly difficult at sawmills where large amounts of sawdust are produced by the sawmill but in varying amounts according to the mill activity.

In view of the irregular amount of sawdust produced over the work day of the sawmill, the mill owner usually stock piled the sawdust and then removes it from the mill site before burning to avoid noxious ordors and ash due to incomplete combustion.

SUMMARY OF THE INVENTION

In accordance with the invention claimed a method of monitoring and controlling the burning of an uneven stream of refuse is provided where the stream of refuse is either burned or stock piled according to the operating condition of a new incinerator.

It is, therefore, one object of this invention to provide a new and improved system for burning refuse.

Another object of this invention is to provide an improved system for wither burning or stock piling an uneven flow of refuse according to the operating conditions of an associated incinerator.

A further object of this invention is to provide an improved incinerator.

A still further object of this invention is to provide an improved, inexpensive incinerator and method for operating it that monitors and handles an uneven stream of refuse by burning or stock piling it repeatedly with little or no need for maintenance.

A still further object of this invention is to provide an improved incinerator employing a controlled swirling burning action which completely consumes the refuse.

A still further object of this invention is to provide an incinerator control system handling a variable refuse imput which is modular in configuration permitting easy repair and replacement of system components.

Further objects and advantages of the invention will become apparent as the following description proceeds and the features of novelty which characterize this invention will be pointed out with particularity in the claims annexed to and forming part of this specification.

BRIEF DESCRIPTION OF THE DRAWING

The present invention may be more readily described by reference to the accompanying drawing in which:

FIG. 1 is a front view, partially in section, of an incinerator and embodying the invention;

FIG. 2 is a cross sectional view of FIG. 1 taken along the line 2 -- 2;

FIG. 3 illustrates schematically the apparatus and controls for monitoring and operation of the incinerator shown in FIGS. 1 and 2; and

FIG. 4 is a block diagram of a system for handling an uneven stream of refuse and particularly the monitoring and control of the operation of the incinerator shown in FIGS. 1 and 2 under optimum conditions.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring more particularly to the drawing by characters of reference, FIGS. 1 and 2 disclose a refuse burning furnace or incinerator 10 comprising a combustion chamber 11 concentrically arranged within a housing 12 and having a smoke-stack 13 forming an exhaust outlet 14.

The combustion chamber is preferably cylindrical in shape as shown, having a wall 15 which may be metal such as iron with an inner lining of an insulating material such as fire brick 16. The vertically extending wall 15 of the combustion chamber 11 is symmetrical about a vertically extending central axis 17. Noncircular combustion chambers can be used although it is preferred to have a circular wall to increase swirling action within the chamber as hereinafter described.

Although not shown in FIGS. 1 and 2, a door may be provided in housing 12 to admit service people, if needed, to examine and or repair the combustion chamber 11.

The material to be burned is admitted tangentially of the fire brick of the combustion chamber 11 through an opening 18 extending through wall 15 and fire brick 16.

The waste material or refuse may be continuously admitted through a pipe line or stock piled away from the incinerator according to the operating conditions of the incinerator as hereinafter described. Although the flow of refuse to the incinerator may be reduced or stopped during its continuous operation, it is a continuous operating system rather than batch operation as used in the prior art.

The wall of the combustion chamber formed by the metal wall 15 and fire brick 16 is provided with at least one or more horizontal rows of tubular vents 19. The tubular vents 19 are preferably identical to each other although their dimensions and shape can vary. In the embodiment illustrated nine identical rectangular vents are used in each of the three rows. These vents are spaced uniform distances apart about the perimeter of the chamber and each having a central axis 20 arranged at an angle X of less than 90° to a radius R extending in a horizontal plane from the center of the combustion chamber. Preferably angle X is 45° and the central axis of each vent lies in a plane perpendicular to vertical axis 17. Thus, the passageways formed by each tubular vent in the rows are inclined or tangential to the circle formed by wall 15 and permit entrance of airflow in the direction of arrows 21 to create a swirling action as illustrated by arrow 22 at each level of each row. This action provides a centrifuge-like action to burning particles, causing them to swirl about the incinerator and to be completely exposed to the air entering from the tubular vents.

As the gases and particles rise from the bottom row to the top row, they are constantly moved in a swirling action to provide for complete exposure to entering air carrying oxygen and therefore complete burning.

Although the vents 19 are shown to provide counterclockwise motion of the burning gases these vents could readily be directed in the opposite direction to provide clockwise movement of the burning particles.

The upper row of vents 19 supply air to complete combustion and to dilute the gases leaving through stack 13 and exhaust outlet 14.

Each vent 19 can be provided with a conventional damper or adjustable cover plate (not shown) at their outer ends for permitting complete opening of the passageway of each vent, partial opening or complete closing thereof to adjust the amount of environmental air admitted to the burner as desired.

Preferably a funnel shaped section 23 connects the combustion chamber 11 with the smokestack 13.

As shown in FIG. 1 the air under pressure to vents 19 is provided through pipe line 25 which is controlled by a damper or motor controlled butterfly valve 26. This air is directed tangentially along the space 27 between the inside surface of housing 12 and the outside surface of wall 15. Since this space is enclosed by the funnel section 23 at the top and a footing or concrete slab 28 at the bottom on which the incinerator is mounted, the only outlet for this air under pressure is through vents 19.

During operation of the incinerator the rows or tiers of vents 19 provide, in addition to the air moving the refuse into the incinerator enough air to provide for substantially complete burning of the refuse particles. The refuse is directed into the incinerator 10 by air under pressure in pipe line 30 through refuse opening 18.

Air from pipe line 25 through vents 19 is injected varying velocity into the combustion chamber augmenting the circular motion of the refuse and oxidizing the particulate matter in the plane of each row of vents until the refuse material is completely consumed with substantially only hot gases rising up through the stack carrying little or no ash.

In order to control and retard the movement of the cyclone burning action of the refuse through the incinerator a ridge or ledge 31 is arranged to protrude inwardly from the fire brick 16 as shown in FIGS. 1 and 2. This ledge is arranged between the two lower tiers of vents 19 but above the refuse opening 18. This ledge retards the movement of the refuse material until the heavier mass of burning particles has been consumed thus assuring that the mass of burning particles does not move through the incinerator until it has been consumed.

In order to burn material such as sawdust or other like material evenly and throughly this refuse material is transmitted into the incinerator on or with a stream of air under pressure.

FIG. 3 illustrates schematically the devices for controlling the operation of the incinerator and protecting it from overheating and malfunctioning.

As shown in FIG. 3 refuse such as sawdust is disposed in a hopper 33 by any suitable means such as a conveyor belt or truck, not shown, which then is withdrawn therefrom by a blower 34 which transmits it with a given supply of air under pressure through pipe line 30 and opening 18 to the interior of the incinerator.

A suitable valve means 37 is provided in pipe line 30 between blower 34 and opening 18 for directing the sawdust and air under pressure to opening 18 and the interior of the incinerator or to a stock pile (not shown) through a pipe line 38. Valve means 37 is electrically controlled by a sensor 39 mounted in a suitable place in the smoke stack 13 or a sensor 40 mounted in pipe line 30 near opening 18, both later described in more detail.

INCINERATOR IGNITION SUB-SYSTEM

In order to ignite the refuse as it enters the incinerator and to later deenergize the igniting means when the flame in the incinerator can support itself, a gas fuel supply and ignition means 41 is connected to the refuse inlet pipe 30. The gas fuel supply and ignition means comprises a pipe line 42 connected to a suitable natural gas supply under pressure (not shown).

Pipe line 42 is then connected through a natural gas shutoff valve 43, pressure regulator 44 and automatic gas shutoff valve 45 to a natural gas and atmospheric air mixing blower 46. From blower 46 the mixture of air and gas is piped to the gas burner nozzle 47 which is directed through opening 18 into the incinerator.

At a point between the natural gas shutoff valve 43 and the pressure regulator 44, a pilot gas supply line 48 is provided which pipes a limited supply of natural gas through an automatic gas pilot shutoff valve 49 to the gas burner nozzle 47.

The gas burner nozzle 47 is positioned in the refuse conveyor duct or pipe line 30. As heretofore mentioned in this embodiment, wood waste is the refuse. The wood particles flow around and past the burner nozzle and are ignited by the burner flame as they pass into the incinerator combustion chamber through opening 18.

Natural gas entering the gas burner nozzle 47 through gas pilot shutoff valve 49 is ignited by a suitable spark plug 50. A flame sensor 51 is mounted in the gas burner nozzle 47 to generate electrical signals for transmission to a protective relay 52 hereinafter described. Contacts 53 within relay 52 are normally closed to supply power to automatic gas shutoff valve 45, causing it to open, allowing natural gas to flow through blower 46 to the burner nozzle 47 where it is ignited by the pilot flame.

A time delay device 54 in the electrical circuit 55 connecting contacts 53 of relay 52 to the pilot gas shutoff valve 49 interrupts the circuit after a predetermined time causing valve 49 to close and thereby stopping the flow of gas through pipe line 48 to the pilot light or flame.

In the event the pilot flame is not ignited, a signal from the flame sensor 51 is transmitted to the protective relay 52 and after a short delay the protective relay 52 operates to interrupt electric circuit 55 to pilot gas shutoff valve 49 causing it to close. The pilot ignition sequence may be repeated by depressing a reset button on the protective relay, as well known in the art. If gas flowing through the gas burner nozzle is interrupted causing interruption of the gas flame, flame sensor 51 will generate a signal which will be transmitted through conductor 56 to protective relay 52 which will interrupt the electric circuit to the automatic gas shutoff valve 45 to stop the gas flow.

Shutoff of the gas burner nozzle 47 when the gas emitted from the smoke stack 13 reach a given temperature is accomplished by a chromel-alumel thermocouple probe type sinsor 57 mounted in the incinerator smoke stack. At a pre-selected temperature (approximately 850 degrees F) a signal from the sensor is transmitted through conductor 58 to a temperature controller 59 and to protective relay 52 which in turn causes the automatic gas shutoff valve 45 to close and shut down the gas burner nozzle action. If the exhaust gas temperature in smoke stack 13 falls below the selected temperature (850 degrees F) electric power is restored to the protective relay 52 and gas shutoff valve 45 is automatically opened and the gas flowing out of gas burner nozzle 47 is reignited.

Sensors 51 and 57 prove safeguards for causing shut down of the incinerator and particularly extinguishing of the flame out of gas burner nozzle 47 during automatic relighting should a malfunction occur.

WASTE WOOD FLOW CONTROL SUB-SYSTEM

In order to protect the system disclosed against the filling of the incinerator with unignited waste in the event the gas burner system fails during start up of the incinerator the thermocouple probe or sensor 40 is located in the waste conveyor pipe line 30 in a position exposed to the flame emitted from the gas burner nozzle 47. A temperature controller 62 receives an electrical signal from sensor 40. When the gas emitted by gas burner nozzle 47 is ignited and the sensor is heated, the temperature controller 62 at a preselected temperature of approximately 400 degrees F transmits a signal through conductors 63 and 64 to energize blower 34 and open valve means 37, respectively, to initiate waste wood flow through the pneumatic conveyor duct or pipe line 30 and into the incinerator.

If the temperature sensed by sensor 40 drops below the set temperature of 400° F the controller 62 either interrupts the electric circuit to blower 34 or closes valve means 37 and directs the wood waste flow out of pipe line 38 for stock piling purposes. If the temperature sensed by sensor 39 drops below the set temperature of 800° F. for example, the controller 69 also either interrupts the electric circuit to blower 34 or closes valve means 37 and directs the wood waste flow out of pipe line 38 for stock piling purposes.

INCINERATOR TEMPERATURE CONTROL SYSTEM

Normal operation of the incinerator results in exhaust gas temperatures in the range of 850° to 1400° F, for example. The incinerator temperature is controlled by sensor 39 which is installed in the incinerator smoke stack 13 and is electrically connected through a conductor 65, a temperature controller 66, conductor 67 to the motor controlled butterfly valve 26 in a duct line 25 connected to a blower 68. The temperature controller 66 is adjusted to set the temperature for actuating of the butterfly valve at any desired value such as 1,200° F.

As the thermocouple sensor 39 senses the preselected temperature it generates a signal which actuates the temperature controller 66 and initates a predetermined movement of the motor operated valve 26. When the temperature of the smoke stack 13 rises past a set temperature, the signal generated by sensor 39 moves the butterfly valve 26 toward its open position to admit more diluting air thereby lowering the exhaust gas temperature in smoke stack 13. When the temperature falls below a set value, the butterfly valve is driven toward a closed position to reduce the diluting air flow in the housing 12 of incinerator 10 to cause the exhaust gas temperature to increase.

Temperature controller 66 used herein incorporates a proportioning control function that causes it to drive the motor operated butterfly valve 26 in either direction from any position of valve travel. It is not necessary for the motor of butterfly valve 26 to move to a full travel limit before it can be reversed. This increases the temperature control responsiveness and increases the life of the system components.

OVER TEMPERATURE CONTROL SUB-SYSTEM

This sub-system partially described heretofore automatically stops wood flow to the incinerator in the event a malfunction occurs resulting in excessive exhaust gas temperature. Such malfunction could be due to failure of the air blower 34, valve means 37 or the temperature controller 66, among other things.

When the sensor 39 senses a predetermined temperature such as, for example, 1500° F the controller 69 transmits a signal through conductor 70 to blower 34 to interrupt current flow thereof, thereby stopping blower action and waste wood flow to the incinerator.

Simultaneously, an alarm 71 (which may be a light or bell) is actuated to alert an operator to the over-temperature condition. Controller 69 then requires manual reset before operation of the incinerator can be resumed. This helps assure that the malfunction will be corrected before operation of the incinerator is continued.

SYSTEM OPERATION

FIG. 4 illustrates in block diagram form the operation of the system disclosed.

This system is essentially mill operated and controlled from a panel 72, including thereon suitable start-stop buttons or switches controlling various sub-systems of the system. When it is desired to operate the system, an operator closes an air supply start-stop switch 73 which through conductor 74 electrically energizes blower 68 of the air supply sub-system furnishing secondary air to vents 19. At this time the start-stop switch 75 on panel 72 is closed and an electrical connection is made from a source of electric current through conductor 76 to the atmospheric air mixing blower 46. Simultaneously, current flows through conductor 77, a transformer 78 in the incinerator control to protective relay 52, a temperature controller 59 and ignition transformer 79 energizing spark plug 50. Transformer 78 also energizes controllers 66 and 69.

Upon the operation of the protective relay 52, the automatic pilot valve 49 and main valve 45 are controlled as heretofore described.

Upon operation of the automatic main valve 45, a main valve position light 80 on the mill control panel 72 is actuated to indicate the position of this valve.

In accordance with the above, a burner system is disclosed which is particularly adaptable for hogged wood particles or sawdust waste. The hogged wood and sawdust may be transported to the incinerator by a pneumatic conveyor. The incinerator's combustion zone, in addition to receiving wood waste and its carrying airflow, is also supplied with sufficient air to complete combustion of the waste within the confines of the combustion zone. The resulting products of combustion entering the stack are at a sufficiently elevated temperature to burn all resinous vapors and particulate matter.

Since proper combustion is a function of combustion product temperature and air to fuel ratio, automatic control of the combustion airflow is provided responsive to stack temperature. Once the burner reaches its normal operating temperature the automatic control modulates the airflow to maintain burning in a completely smokeless state.

The incinerator is shown in a vertical position although it could be arranged in a horizontal plane.

Although but one embodiment of the present invention has been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.