US1316086A - Heat-recuperating process and apparatus for blast-furnaces - Google Patents

Description

l. P..DOVEL.

HEAT RECUPERATING PROCESS AND APPRATUS FOR BLAST FURNACES.

y APPLICATION FILED DEC. 21. |918. 1,316,086. .Patented sept. 16, 1919.

l A if JAMES I? Dove.

THE COLUMBIA PLANouR/wn cn., wASHlNnToN. n. c,

JAMES P. DOVEL, OF BIRMINGHAM, ALABAMA.

HEAT-RECUPERATING PROCESS AND APPARATUS FOR BLAST-FURNACES.

Specicationof Letters Patent.

Patented Sept. 16, 1919.

Application led December 27, 1918.` Serial No. 268,536.

T 0 all lwhom 'it may concern.'

Be it .known that I, Janus P. DovEL, a citizen of the United States of America, residing at Birmingham, in the county of Jefferson and State of Alabama, have invented certain new and useful Improvements in Heat Recuperating Processes and Apparatus for Blast-Furnaces, of which the following is a specification.

My invention relates to a heat recuperating process and apparatus for blast furnaces, my object being to devise means whereby the equivalent of a closed circuit may be established for the heat units that have heretofore escaped from the furnace stoves through the stack toy the end that by an extremely simple and practicable means the temperature of hot blast may be maintained vhigher without fuel expense than normal or may be maintained at normal temperature by the use of a less number of stoves.

A further object of my invention relates to its use in connection with a stack induced draft wherein an automatic agency is provided to( permit the escape from the closed heat circuit of just suflicient heat units to maintain a uniform stack draft, this being accomplished preferably by means `of an automaticvalve responsive to stack temperatures and adjustable to control the voluniey of cold air which is shunted through the recuperating agency. By thus maintaining my stack induced draft substantially uniform in the stoves, the volume of air and gas canbe so proportioned as to produce perfect combustion and highest eiliciency from the gas consumed, this not being` possible with the irregular, variable draft which is obtained from stacks under the present practice. The air and gases are not admitted to the stoves under the same conditions, the gas being under pressure,

and the air not being under pressure, and the saine volumes of air and gas are different, and when it is considered that the variable stack induced draft will affect the entering volume of gas and air to an indefinite degree it will be apparent that the stove valves cannot be adjusted to maintain approximately perfect combustion conditions in the stoves. My invention will greatly assist in this respect by eliminating the variable draft and to that extent will simplify the control of the stove valves and improve their operation and stove efficiency.

in section and recuperating coils in side elevation.

Fig. 2 is a plan view of the recuperating coils; and

Fig. 3 is a detail view of the automatic valve and its thermostatic regulator.

Similar reference numerals refer to similar parts throughout the drawings.

In the embodiment of my invention illustrated, 1 is the hot main leading from the stoves 2 to the blast furnace, not shown, and 3 is the stack flue having a manifold connection controlled by the valves 4 with the several stoves at one end and at the other end being connected to the stack 5 or equivalent draft agency. This stack flue is provided with an enlarged recuperating chamber 6 at some intermediate point between the stoves and stack and in this chamber is disposed an air heating arrangement of any suitable character such as the coils 7 connected tothe header pipes 8 at each end which inl turn have connection by pipes 9 with the cold air main 10 to the stoves. Valves 11 and 12 are provided in the pipes 9 and between the points of connection of said pipes with the cold air main I interpose a valve fitting 13 having therein as typical of anyvsuitable valve a vertically adjustable gate valve 14:, the stem 15 of which is connected lto a bell crank 16 pivotally mounted on a standard 17a on the pipe 10 and having its vertically disposed crank arm connected to the free rend of a brass bar 17 forming a thermostat, the other end of which is caused to pass slidably through a stufling box' 18 at one side' of the stackand to traverse the stack diametrically and be anchored by plates 19 in the opposite wall of the stack. The bell crank is given adjustable connection to the stem of the valveby providing the bell crank with a yoke end 20 which works between the nuts 21 screwed on the valve stem'.

In operation, having determined the desired stack temperature necessar to maintain the proper draft, say 400 ahrenheit, the adjustable connections for the automatic CII QBEST AVALABLE COPY valve are regulated so as to leave this valve fully open when the stack temperature stands at 400o Fahrenheiufthe valves -11 Pandit 12 being keptopen, under which conditions the entering" cold.` air willV be' `shunted pastl the heating coils on its way to the stoves and J`vvillf therefore not be `preheated beforereaching the stoves. As-the, stack temperature rises above the predetermined maXimumof say `400O-Fahrenheit aneXpansion ofthe thermostatic bar results, which in. turnfproduces a gradual closing of the` automatic valve in the `cold air main, thereby' shuntinga por-tion of the cold air through the' heating lcoils, thus preheating the air' and reducing the staclctemperature. As the stack temperature y'tends yto vary the automatic valve functions tofcontrol the volu-n` metric flow of. air through thev recuperating f f coils, so proportioning the latter as to eX- y tract all. surplus' heat units Ifrom the `furnace gases above the predetermineduninr, mum fondraft purposes,- these heat units are passed backl without -appreciable loss into 4the stoves, thuscreating a closed circuitfor the heat units from which only a predetermined amountis ermrtted to escape If anarti- Aicial force draft is employed, the minimum` stack temperaturey may be -reduced -tothe point. wherethe `heat `units are practically j in a closed circuit.,

There are many important advantages-.-y which flow from--this extremely simple and c. practical idea forthewrecuperation of heat, f such 1forinstance, as: the highly desirable condition ofva uniform draft, thev reduction f? in thefnumber .fof stovesfby reason of the greater-lengthof timefwhichf the stoves can be useddue-,to the preheated condition of the air supplied; the factthe furnace temperatures can-,be run to `abnormal points heretofore'considered impractical by reason f ofthe excessiveheat .'losses, known as stack losses; and-fthe reduction-'in the amount of fuelrequired for-,the-.blast furnace burden. by reason of the=higher temperatures of the air blast. f"

Iny my pending" application September-- 21st, 1915, `Serial No. 51,882, I have heretoforeproposed to pass the hot gases iowing from .blast furnace stoves through boilers topartially recover-the waste heat, but it is not possible by such agency to obtain thel contemplated closed circuit for the waste heat lunits,l nor to exercise reliable control over the draft, orto lmodify'the functioning ofitheistoves or-the blast furnace practice as it hasiheretofore prevailed, -all of which are made possible bythe utilization of the waste heat for -preheating'the-cold air supply to i the stove-in a shunted circuit, and I desire to claim such method and the means for practising it broadly and without restrictionsto .the specific! agencies shown.

Having described my invention, what I claim=asnew and-desire to secure by Letters Patent, is

1. The'hereindescribed heat recuperating process for blast furnaces, which consists in transferring heat from the waste gases leaving the blast furnace stovesto-the cold'air blast for1 the furnace, thereby setting up a closed circuit for the heat units, and withdrawing Asuiiicient heat units from said closed circuit to maintain. a substantially uniform temperature in the gases at their point of discharge.`

2. In combination, blast furnace stoves, a main for the waste gasesconducted therefrom, a heat vrecuperating yagencyr exposed to waste gases, and automatic means responsiveto thev temperature of the gases leaving said .agency to ,pass a predetermined volume of the ccoldairy supplied fto the stoves through'zsaid agency.v

3. In combination, blast furnace stoves, a main l for the waste gases conducted therefrom, i a heat Yrecuperating agency exposed tol waste gases, :a cold air main `for the stoves, a shunt,circuit-from'fsaid main which4 includes said agency, valve means to control the volume of air shunted through said agency, andthermostatic means responsive to .stack f temperature to `automatically adjustsaid valve means.

4. In'combination, blast furnace stoves, a stack fiue leading therefrom, `a cold air main for` the stoves, a heat recuperating agency in said flue, .pipe means to shunt cold air from said main through said agency, a valve inrthe cold air main between the points of diversion and return of'saidshunt air circuit, and a thermostat in the sta-ck for automatically vkadjusting said valve.

5. In combination, blast `furnace stoves, a stackl flue leading therefrom, a cold air main forthe stoves,a heatfrecuperating agency in saidflue, pipe meansy to shunt cold air from said main through said agency, a valve inthe,` coldair mainfbetween the-points of diversion and returnof said shunt air circuit,landra thermostat in the stack for automatically adjusting said valve comprising a metal bar which traverses: the stack being anchored thereto at its inner end and connected to the valveat its outer end, substantially -as described.

Intestimony -whereof I afix my signature.

JAMES P. DOV'EL.

Witness NoMm WELSH. i l

Uopieliof thiLpatentmay-be obtained for ve cents each,lha/'addressing'.the #Commissioner of Patents, Washington, D, GHF.

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