US2899188A - Bjegenerating air heater system - Google Patents

Description

Aug. 11, 1959 G. BENDER ETAL AREGENEMTING AIR HEATER SYSTEM 'Filed Nw. 15, 1955 e e Q) a N p n M S S S r w A/ r m m w w M aM vH a o /Z L k m v.

z. A j m .A 1 T T United Sttaes PaterA REGENERATING AIR HEATER SYSTEM Georg Benjdvery,leuna,r Kreis -Merseburg, and Alfred Krauthakel, Bad Durrenberg, KreisMerseburg, Germany, assignors Vto VEB Leuna-Werke Walter Ul'- b'iclrt, Leuna, Kreis" Merseburg, Germany Application November 15, 1955, Serial No.- 546,926

This invention relates to arrangements for use in connection with blast furnaces, low shaft blast furnaces, and apparatus for the manufacture of1 city gas or synthetic gas, especially to the systems of regenerating air heaters and regenerating gas heaters of the type also known as Cfowpersstoves` for use in connection with blast furnaces. y

Hitherto customary multi-regenerating air heater systems comprising a plurality of regenerating air heaters of thetype also knownas Cowpers stoves are fitted and lined with refractory stonework. When such customary multi-regenerating air heater systems are used for the operationv of blast furnaces, the ue gases and the blow air or blow gas enter the places of action in the blast furnaceewith-heavy periodiciluctuations of the temperature, which may amount up to 3'50 C. in systems having two Cowpers stoves. At the start of a period of blowing the blow air or blow gas -is heated to a maximum temperature by the very hot stones of the lining. Then, during the period-of blowing a portion of the accumulated h eat is transferred to the blow air or blow gas whereby the temperature ofV the stones of the lining is reduced to aigreat extent so that the blow air or blow gas leaves the Cowpers stove .at a. lower temperature at the end of the period of lblowing'. During the period` of heating similar phenomena occur, i.e.V at the start lof the period of heati-ngithe-ue gases leave the Cowpers stove ati acomparatively' low temperature and atV the end of `the period of heating at. a higher temperature. These fluctuations ofthe temperature disturb very much conditions for a uniformoperation at the .place of action in -the, blast furnace. A

In ordertoovercome said disadvantages it has been proposed to add a third Cowpers Astove to such` a system. Although the fluctuations `of the temperature are less in suchsys't'ems comprising three Cowpers stoves,v they still range up to 260 C. depending on the methodv of operation,

For the operation of blast furnaces it also has been proposed to control automatically these disadvantageous uctuations of the temperature of thehot blow air or blow gas leaving the Cowpers stove by adding cold` air bythe so-called coldblast valve so that ablast temperature as uniform as possible is' maintained from the beginning to the end of the period of blowing. This is done customarilyin'ts'ucha way that `the* cold blast valve` is t'urnedofvperiodically, so that it is closed attheend of the period of. blowing.` with the result that the blowf air or blow gas reaches the blast furnace at the exit temperature ofthe Cowpers stove,rwhile at the start of the period of blowing so much cold air is added that, prior to the entry ofthe air or gas into the blast furnace, the exit ternperature of the Cowpers stove, being at this `time much highenis reduced to a temperature substantially equal to the exit temperature :of the Cowpers stove at the end ofthe period of blowing.

An object of the invention isto vovercome the disad- 2,899,188 kPatented Aug. ,11, `1959 ICC vantages of the hitherto customary multi-Cowpers stove systems. l K

According. to the present invention, means are provided to produce a substantially constant temperature of the hot gases which enter-the place of action ofl the reactorfrom the Cowpers.,y Such means comprise a heat accumulator through which the hot gases pass on their way to the-reactor. The heat accumulator acts as Va heat equalizer,- collectingV and-storing heat from the hot gases at vthe beginning 4of the operating.periodfofl theCowper, and later transferring the stored heat to'V the cooler gases which leave `theCowper at the endofthe operating period.- Thus, the gases are fedv to thereactor at a substantially constant temperature `over the entire period fof operation-of the Cowper; Thisisfparticulrly useful in blastl furnace operation,.,where=the gases fed to the blast furnaceshould be as hot as possible an'd at the Asalme time as uniform7 in temperature as possible; ln addition, it is useful in production: of-city gas from .low temperature carbonization gas, synthetic-gas production, andthe-like'.-

Another `objectoffthe present' invention isV to provide al multi-Cowpers stove system ofthe Vcharacter described, bymeans of which1undesired uctations intlie temperature of' the gas emitted thereby may be avoided. This is done-without unduly decreasing thepover-all temperature'of the gas, as results-from the cold blastvalve method previously des -:ribed.

Still another--objectof-the invention isk the Vprovision of a multi-Cowpers stovef systemof the character. described -Which may i be incorporated. into existing.T regericrafting` air heater or gas heater systems. I

Av further object-ofthe .invention is-the provision of Aa multi-Cowpers stove system. ofthe character described in` which-.a -heat accumulator is provided'` for Vequaliing the temperature ofl the vairvor gas emittedbyeach Cowper during-,the blowing-period, and a second heat vaccumulator is provided for equalizing the-'temperature of-the burnedheatinggases emitted from .ea-cli Cowper during the-burni-ng-period.. d l

Other objects and structuraldetails of thevinvention will `be` apparent frornthe following. description When read-)in` conjunctionI l.with the accompanying drawings forming. part of-this specification, whereirl:V

l is adia-grammatical illustration-.ofastwo- Cowpers stove system according to the invention,ancl

Figs. 2-4 -areigraphsi'llustrating the'uctuations ofthe temperature of. various `Cowpers -stove systems.

Referringv now to 1?ig..l,VA l-tgenerallyindicates a: rst Cowpers-stove op regeneratinga-ir heater or regenerating gas heater, and Z-generally indicates a secondy Cowpers stove--v or regeneratingI air heater orV regenerating gas heajter.- l* I A The heating gases introduced into the system' through alinei lenter Vthe-Cowpers stove-flrthrough theconduit 18ct` a control valvel 4 vand the lineZtl, whenthe control valve .4l isinfthe position shown-in full lines. The heating gases are burned andi leave the Cowpers stove I as iiue gases passing'through thez line-ZZQ-andV theV conduit .241 of another control valve 5 when the latter is in the position shown in` full lines.r After VIpassing thel control vvalve 5, theflue gases reach the l-ine'ad, vwhichfYco-nductsl same through a heat accumulator 7` to the place or chamber 8 of actionwof a reactor, such as. aA blast furnace for exampler The blow lairy or blow gases introduced into the syst'em during the sam'e time (first period.) through a line 9 enter the other Cowpers stove-ithrough the conduit 26 of thecontroll val've 5 and the line 28, when said control valve 5l is in the positionshown. inthe-.full lines.- Said blow air or blow gases b eing discharged froml the Cowpers stoveflf` throughY the line .30" reaches arline I0 through the conduit 32 of the control valve 4, when the latter is in the position shown in full lines. The line leads the blow air or blow gases through another heat accumulator 11 to the place or chamber 12 of action of a reactor, such as a blast furnace for example. The blow air or the blow gas passes through the heat accumulator 11 and the flue gas passes through the heat accumulator 7 at all times in the same direction.

Upon moving the control valves 4 and 5 into the position shown in dash lines for the performance of the second period, the heating gases or flue gases respectively pass through the Cowpers stove 2 and line 6 to the place 8 of action, while the blow air or blow gas passes through the Cowpers stove 1 and the line 10 to the place 12 of action.

Each heat accumulator 7 and 11 contains the usual means for collecting, storing, and transferring heat of the gases passing therethrough, as for example heat refractory stones or other material. As the blow air or gases leave the respective Cowpers stoves 1 and 2 during the blowing period thereof, they pass through the heat accumulator 11. During the beginning of the blowing period, the refractory material within the Cowpers stove has just been heated by the burning gas and is relatively hot. The blow gases passing therethrough are heated to a relatively high temperature, but lose some of their heat in heating the refractory material of the heat accumulator 11. As the blowing period progresses, the refractory material in the Cowpers stove loses some of its heat and the blow air or gases becomes relatively cooler, upon leaving the Cowpers stove. This loss of heat is however compensated by heat obtained when the gases pass through the heated refractory material of the accumulator 11. Thus, the gases arriving at the place of action 12 of the reactor are maintained at a substantially constant temperature over the entire blowing period. Similarly the burned flue gases entering the place of action 8 of a reactor are maintained at a substantially constant temperature by the accumulator 7.

In Figs. 2-4 the ordinate represents the temperature in degrees centigrade whereas the abscissa represents the time in hours. 'Ihe curve 13 of Fig. 2 illustrates the periodic fluctuations of the temperature of a hitherto customary two-Cowpers stove system and the curve 14 of Fig. 3 illustrates the reduced uctuations of the temperature of a hitherto customary three-Cowpers stove system. Curve 15 of Fig. 4, however, clearly indicates the largely reduced uctuations of the temperature of a two- Cowpers stove system according to the invention.

As may be readily gathered from the graphs of Fig. 2-4, the two-Cowpers stove system according to the invention (see Fig. 4), including the arrangement of the heat accumulators 7 and 11, is much superior to the hitherto customary two-Cowpers stove system (see Fig. 2) and to the much more complicated three-Cowpers stove system in so far as the fluctuations of temperature are concerned.

When the multi-Cowpers stove system according to the invention is used for the operation of a blast -furnace, the arrangement of the interposed heat accumulators renders possible the maintenance of a substantially uniform temperature of the blow air or blow gas prior to its entrance into the blast furnace, without necessitating a cooling off of the hot blow air or blow gas discharged from the Cowpers stove by subjecting the same to cold air by means of an automatically controlled valve. Owing to the arrangement of the heat accumulators according to the invention a mean temperature may be obtained which is between the two temperatures prevailing at the outlet of the Cowpers stove at the beginning and at the end of the period of blowing. If, however, a Cowpers stove system of hitherto customary arrangement is operated with a control of the temperature by a cold air valve, only the lower temperature prevailing during the end of the period at the outlet of the Cowpers stove may be adjusted. Thus, the arrangement of a heat accumulator according to the invention renders possible to obtain a considerably higher temperature of the blow air or blow gas in existing blast furnaces and to build new installation in a less complicated and more economical manner, if only the hitherto customary tempera ture of the hot blow air or blow gas shall be obtained.

In a plant for production of city gas from low temperature carbonization gas, in which the plant operated in two periods of one-half hour each, utilization of the invention herein permitted temperature variations of 415 to 819 C. in the flue gas to be adjusted to a medium temperature of 617 C. The low-carbonization gas temperature was adjusted from a temperature variance between 589 and 861 C. to a mean temperature of 725 C. This was accomplished by using two heat accumulators.

The arrangement of heat accumulators according to the invention is also of great importance for the operation of low shaft blast furnaces, as the volume of action of such a low shaft blast furnace is considerably smaller and, therefore, higher temperatures of the hot blow air or blow gas are more favorable.

We have described a preferred embodiment of our invention, but it is understood that this disclosure is for the purpose of illustration, and that various omissions and changes in shape, proportion and arrangement of parts, as well as the substitution of equivalent elements for the arrangements shown and described may be made without departing from the spirit and scope of the invention as set forth in the appended claims.

For example the arrangement of heat accumulators according to the invention may also be made in multi- Cowpers stove systems having more than two Cowpers stoves.

What we claim is:

1. In a regenerating air heater system, the combination including a first and second reactor, a first and second Cowper stove for alternately feeding heated gases and burned ilue gases respectively to said rst and second reactors respectively, means for feeding heating gases to each of said Cowpers for burning therein during a heating period, means for blowing gaseous medium through the heated Cowpers during a blowing period, whereby the gaseous medium is heated as it passes through the Cowpers interior, conduit means connecting said first Cowper to said rst reactor for transporting the gaseous medium to the latter, second conduit means connected to said second Cowper and said second reactor for transporting the burned flue gases to the latter, a heat accumulator in each of first and second conduit means between the associated Cowper and reactor, said heat accumulator being adapted to collect heat from the gaseous medium and flue gases at the beginning of the blowing period and to transfer the collected heat to the gaseous medium and ue gases at the end of the blowing period, whereby the gaseous medium and burned ue gases entering the reactor are maintained at a substantially constant temperature over the entire blowing and heating cycle.

2. A regenerating air heater system according to claim l, in which the heating gas feeding means and the gaseous medium blowing means includes valve means for the alternate feeding of heating gas and gaseous medium to be heated to each of said Cowpers, whereby one Cowper alternates respectively between a heating period and a blowing period, while the other Cowper simultaneously alternates respectively between a blowing period and a heating period.

3. In a regenerating air-heating system, the combination of a first and second Cowper stove, conduit means for connecting heating gases to one end of said first and second Cowper stoves, second conduit means for connecting burned flue gas to the opposite end of said first and second Cowper stoves, rst and second reactors, rst and second heat accumulators, means for connecting said rst reactor and said iirst accumulator in series to one end of said iirst and second Cowper stoves, means for connecting said second reactor and said second heat accumulator to the opposite end of said rst and second Cowper stoves, rst valve means at one end of Cowper stoves for alternately directing heating gases to said first Cowper while said second Cowper is connected to said first accumulator and said first reactor and for thereafter connecting said second Cowper to said heating gas conduit and said rst Cowper 10 to said first reactor and said accumulator, and second valve control means at the opposite end of said Cowpers for alternately connecting said first Cowper to said burned flue gas conduits and said second Cowper to said second reactor and said second accumulator and thereafter for connecting said second Cowper to said burned Hue gas conduit and said first Cowper to said second reactor and said second heat accumulator.

References Cited in the le of this patent UNITED STATES PATENTS 1,105,158 Pregarden July 28, 1914 1,924,936 Lehr Aug. 29, 1933 2,141,036 Daniels Dec. 20, 1938 FOREIGN PATENTS 593,692 France Sept. 21, 1926

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