US 2282496 A
Description (OCR text may contain errors)
May l2, i942. w RYAN 2,282,496
' FURNACE Filed Feb. 19, 1941 7b Sigg-k ATTORNEY Patented May 12, 1942 iJNiTED SATES ZZAtl TENT OFICE 4 Claims.
This invention relates to improvements in furnaces and in particular to such improvements which materially increase the eiciency of the furnace.
In furnaces of conventional design the gases of combustion are transferred immediately from the combustion zone to the heating zone wherein they give up by heat exchange their contained heat and are immediately expelled to the atmosphere. The gases from the combustion Zone contain a substantial proportion of unburned constituents which are passed out unchanged through the nues and stack and thereby decrease the eiiiciency of the furnace.
It is therefore the object of my inventionY to provide a furnace which will permit the maximum fuel utilization and which will give increased fuel efficiency.
It is a further object of my invention to provide a furnace which will permit the recirculation of the gases of combustion to the combustion zone until lall of the combustible constituents thereof are substantially completely utilized before the same are passed to the atmosphere.
Other objects of my invention will become apparent from my description thereof read in conjunction with the accompanying drawing which forms a part f this specification and which is a sectional elevation of an embodiment of my invention.
I have discovered that substantially complete fuel utilization can be attained mixing the gases of combustion with air and recirculating the mixture together with additional air and steam into the combustion zone and impinge the tot-al mixture onto a heated surface, such as a baille. When the mixture of recirculated combustion gases, air and steam contact the heated baiile substantially complete combustion of the unburned gases in the recirculated gases of combustion is effected.
A means of carrying out my invention is illustrated by the following description of a preferred embodiment thereof. The single figure is a longitudinal section through a furnace embodying my invention.
Referring to the drawing, a furnace It is provided with a fire door II, a suitable grate I2, and a clean-out or ash door I3. The furnace is provided with a jacket I4 adapted to receive a heat transfer medium, such as water, having a valved line inlet I5 and a valved line outlet I6. A hollow partition I'I extending transversely across the upper portion of the furnace and communicating with the jacket I4 forms, with the top of the furnace I8, a mixing chamber IS. The furnace is provided at the rear thereof and in the upper portion of the combustion Zone 2t with a stack 2I, provided with suitable damping means 22.
The mixing chamber I9 communicates with the combustion zone 20 through an opening 23 in thefforward portion thereof, and through the conduit 24 in the rear portion thereof, extending upwardly into the mixing chamber I9, and downwardly into 'the combustion zone 26' to a point below the stack 2I.
A valved conduit 25 extends downwardly through the opening 23 to a point in the combustion zone 20 slightly below thel partition I1 which provides means for introducing air or other. oxygen-containing gases into the combustion zone 2U. Concentric with the conduit 25, a steam pipe 26, provided with suitable valve means 21, directs steam into the conduit 25.
Located in the combustion zone 26 directly beneath the conduit 25 is a baflie 28 provided with aiplurality of openings 29, and suspended by suitable adjustable suspension means 32B, adjustable from the exterior of the furnace, such as by a cam lever. The baie 28 is fabricated of heat resistant material, preferably fire-brick or similar heat resistant ceramic material.
A valved conduit 3|, extends into the mixing chamber I9 to the rear portion thereof, and provides a means of introducing air or other oxygen-containing gases into the mixing chamber I9.
The advantages of employing a furnace embodying my above-described invention may be readily comprehended from the following description of the operation and function thereof.
I-Iot gases resulting from the combustion of the fuel in the combustion zone 20, rise in the combustion zone 2i) and ascend through the conduit 24 into the mixing chamber i9 wherein it is commingled with air introduced through the conduit 3|. As the hot gases in the mixing chamber I9 give up some of their heat te the body of water in the adjacent jacket I4 and the jacket forming the partition Il, the cool air-gas mixture descends to the combustion zone 28 through the passageway 23.
Air, introduced through the conduit 25, and steam, introduced through the steam line 2E,
are -admixed with the recirculating gas-air mixture from the mixing chamber I9. The steam may be that from any source and may be taken directly from the furnace after sufficient steam has been generated. The admixture of air, steam, and recirculating gases of combustion impinge upon the hot perforated baffle 29, and the unburned constituents of the recirculated combustion gases burned. The baffle 29 attains a 5 tion zone pass up the stack 2l. These gases are Y substantially completely consumed gases, so that substantially no smoke is emitted from the stack 2l. The volume of gases permitted to escape up the stack 2l may be controlled by the damper 22.
My invention materially increases the efciency of the furnace and provides greater fuel economy, since by the recyclingof the hot gases from the combustion zone to the mixing zone and back to the combustion zone adrnixed with oxygen and/or an oxygen-containing gas and steam, I obtain substantially complete utilization of the gases of combustion which would otherwise pass up the stack and not be utilized for useful heating. By providing a baffle, such as baffle 29, in the combustion zone, upon which the returning gases may impinge and be substantially completely combusted, I avoid the necessity of returning those gases to the re pot, where they would become ignited and raise the temperature adjacent the re grate to a point where it is burned out.
While I have shown in a preferred embodiment of my invention a furnace in which the mixing chamber is an integral part of the same, I may modify the described arrangement by providing a mixing chamber external of, but adjacent to the furnace structure, such as a mixing chamber superimposed upon the furnace proper.
While I have illustrated and described certain particular embodiments of my invention, I do not wish to be understood as intending to limit the same thereto, as the same may be variously modified and altered without departing from the spirit of the invention, which is defined by the following claims.
1. In a furnace, the combination with a combustion zone adapted to be occupied by hot gases of combustion produced by the ignition of fuel in said furnace, a stack, a mixing chamber, spaced conduits opening at their upper ends in said mixing chamber and at their lower ends into said combustion zone, the upper end of said conduits extending into the mixing chamber above the upper end of the other conduit, and the lower end thereof extending into the combustion zone below the stack, means for introducing air into the mixing chamber, means for introducing air and steam into the admixed air and gases of combustion from the combustion zone, and a baflie in the combustion zone located below the conduit conducting gases from the mixing chamber to the combustion zone.
2. In a furnace as described in claim 1 in which the baffle is vertically adjustable.
3. In a furnace, the combustion with a combustion zone adapted to be occupied by hot gases of combustion produced by the ignition of fuel in said furnace, a mixing chamber, a stack, a conduit extending into the mixing chamber to the upper portion thereof, and extending into the combustion zone to a point below the stack, a second conduit spaced from said rst conduit, extending into the mixing chamber to a point below the upper end of said rst conduit, and extending into the combustion zone to a point above the lower end of said rst conduit, means for introducing air into said mixing chamber, means for introducing air and steam into said second conduit, and a fire resistant baffle suspended in the combustion zone at a point immediately below said second conduit.
4. In a furnace as described in claim 3 in which the fire resistant bafe is vertically adjustable.