US1977617A - Heating system - Google Patents

Description

Oct. 23, 1934.

E. BLANCKENBURG HEATING SYSTEM Filed 001;. 17 1930 f Fig.1

2 Sheets-Sheet l INVENTOR Km/YB/MC/renfiurq.

Oct. 23, 1934.

.E. BLANCKENBURG HEATING SYSTEM Filed 001;. 1'7 1930 2 Sheets-Sheet 2 INVENTOR fm/w/mc/re/rburq ATTORN Y Patented Oct. 23, 1934 UNITED STATES HEATING SYSTEM Emil Blanckenburg, San Francisco, Calif., as- Signor to Petroleum Conversion Corporation, New York, N. Y., a corporation of Delaware Application October 17, 1930, Serial No. 489,284

Claims.

in systemsof heating which comprise aplurality of heaters of the regenerative type, particularly those commonly designated hot blast stoves.

5 The system of heating to'which my invention relates is one which is adapted to supply heated combustible gas for use in the cracking of hydrocarbon oils in which the heated gas is relied upon to accomplish the cracking of the hydrocarbon material with which it is mingled. The source of such gas is commonly the cracking system itself since such gas is produced in the cracking operation and contains hydrogen, methane and other hydrocarbons and some carbon ,monoxide and may have a fuel value of around 600 B. t. u. per cubic foot. Usually it is also used as fuel for the stoves. The heating of this gas and its combustion give rise toproblems which do not occur when the blast stoves are used for ,heating air, as in the blast furnace industry. In the first place, unless proper precautions are taken, the introduction of air into the stove for commencing the firing period following the heat yielding or so-called blast period, may result .in serious explosion by reason of the presence of combustible gas in the stove; in the second place, the combustion of so rich a gas as distinguished from the low calorific blast furnace gas presents the difficulty that the combustion temperatures produced are too high.

I have undertaken to solve these difliculties while employing a pluralityof stoves as a unit,

by using the combustion gases delivered from a' Figure 1 is a View in vertical section of a.

blast furnace and stack containing an illustrative embodiment of the invention; and

Figure 2 is a plan view of a battery of three of such units.

Referring to Figure 1, 10 denotes a regenerative heater of the blast furnace type of standard construction, which is provided with a burner 13, a vertically extended combustion .chamber'15 and checker-work l'lproviding downwardly extending vertical flues, as shown. Communicating with said flues-is a collecting flue 19 which has therein a chimney valve 21 and communicates with a stack 23 by means of duct 55- 25. Duct 25 has therein a slide valve 2'7 while My present invention relates to improvements stack 23 has a valve or damper 29. For the purpose of recovering heat in the flue gases, I preferably provide an air heater or recuperator 31 which is connectedwith the stack by means of a pipe 33. Accordingly, by 'me'ansof the 69* damper 29 or valve 27, the proportion of flue gases passing through the air heater may be varied as desired. Air under the requisite pres-- sure for combustion is admitted to the air heater thru aconduit indicated at 36, passes through the heater and out thru a duct 37 shown in dotted lines and thence to burner 13. Gas to be burned is supplied from' a main 39 to burner 13 thru a connecting pipe 41.

For the purpose'of employing aportion of the 7 spent flue gases in anycombustionspace, the ducts '25 of the stoves are joined by connectingpipe 42 by means of short lengths ofpipe 43,- eaoh having therein a valve 44. Pipe 42 is connected with a cross pipe 45 and this in turn is 7 joined to a distributor pipe 49 which connects each stove by means preferably of both a pipe 51 having therein a valve 53 leading directly to the combustion space of each stove 10 and also a valved branch pipe 52 leading to burner 13. By thismeans of this supply of flue gas tothe burner, the combustion temperature occurring therein is suitably reduced. In order to provide for circulating the gas as required, a motor driven fan 54 is provided at the inlet of pipe 45. For conducting the purge directly to the stack when this is desired a by-pass 57 is pro-' vided, having a valve 58 and leading from outlet 1'9'to pipe 33. j

Inthe operation of the system it will be understood that a given stove of the system is first brought up to temperature by firing with gas from the main 39 during which operation airis supplied through duct 3'7 which has been preheated in heater 31. Also a portion of the flue gases from duct 25 is recirculated by means 7 of fan 54, conduit 45 and connection 52 to burner 13 and connections 51 to combustion space 15. Since the firing-period is longer than the blasting period, two stoves of the three shown will be heated simultaneously, for a considerable part of .the firing period of each and up to 50% or more of the flue gases will be drawn from the stacks of the stoves on fire and returned through V manifold 45 to the'combustion zone or the burn- 5 er fordiluting the high B. t. u. fuel gas. When a stove has reached the proper temperature, the combustion is stopped by shutting ofi the gas through pipe 41 and the air through duct 37 by means of a valve 38. The next step is to 119 insure that no excess of air is present in the stove, and accordingly the stove is purged by continuing the admission of flue gases from manifold 49 either through the burner 13 or 5 through a side connection 53 for a brief period after the air is shut off. The course of the purging gas is through the stove and then out through the stove and then out through by-pass pipe 57, valve 58 and pipe 33 to the stack. When the stove has been thus freed of air, the gas to be heated, which may be termed the heatcarrier gas, is admitted through valve 56' from,

the cold blast main 55 and allowed to bring the stove up to the pressure prevailing in the oil cracking system. As shown, cold blast main 55 has branches 55. The latter, which have valves 56 therein, are joined to the stovesthrough pipe 19. the cold gas through the stove and conducting t therefrom to the cracking system through a socalled hot blast main (not shown) having connections 59 to each stove. The blast period is continued until the temperature in the stove has dropped below the desired minimum. When this has occurred the supply of carrier gas is stopped and the pressure in the stove is. reduced to atmospheric by bleeding off the carrier gasfrom entering flue 25 andvalve 4A, which would admit the gas to the fan 54, and thus mingle ,this gas with the flue gas from the other stoves. If desired, by-pass 5'? may communicate with a gas holder not shown for storing the carrier gas blown down from the stove to nearly atmospheric pressure. In many instances it may be desired to use a fuel other than the gas produced in the cracking system for heating the stoves. fuel, particularly a gaseous fuel, is of low calorific value, the amount of flue gas returned to the combustion zone or to the burner for dilut- 59 ing the fuel gas will of course be less or may be omitted entirely during the firing period. It may be advantageous to use natural gas having a calorific value of 1,000 B. t. u. or more, in which event the flame temperature would be far in excess of the optimum and likely to damage the brickwork of the combustion chamber. It is desired thenio greatly dilute the fuel gas with the recycle flue gas within the burner, to- .gether with the preheated air for combustion. 0 It may also be desirable to have available steam which may be used to supplement the flue gas used for purging and for this purpose a source of steam 60, Figure 1, preferably superheated, is .provided. Many other changes may be made 5' in the method and apparatus described in detail without departing from the spirit of the invention or from the scope of the appended claims.

I claim: 1. In a system for supplying heated combustible gas suitable as an aid in the, cracking of Where a hydrocarbon oils, the method of operating a plurality of hot blast stoves which consists in heating a given stove by burning fuel therein, and then, when the stove has reached the desired temperature, discontinuing the heat, and passing through the stove products of combustion from another stove which is being heated, whereby to purge same of air.

2. In a system for supplying heated combustible gas suitable as an aid in the cracking of hydrocarbon oils, the method of operating a plurality of hot blast stoves, the steps which consist in first heating a given stove by burning fuel therein, then when the desired temperature is reachedybeginning the blast period by passing combustible gas therethrough, continuing the blast until the stove has cooled oif, discon- Ihe blast period is now begun by passing.

tinuing the flow of combustible gas and then purging the stove of said gas by passing through it flue gases from another stove on fire and leading the purge to a stack.

3. In an oil cracking system, an apparatus for heating a combustible gas, comprising a plurality of blast stoves, means for supplying same with a fuel for combustion therein, each of 1 said stoves communicating with a stack, a conduit for leading combustion gases from the stove to the stack communicating therewith, a second. conduit for leadingv a portion of .the produced, flue gas to the combustion zone of said stove and a separate pipe. from the outlet of said stove to said stack, valves in said pipe and said. conduits whereby, when the blasting period is completed, the flue gas from the system may traverse said stove for the purpose of purging same of combustible gases and the purged gas pass through said pipe to the stack and not enter said conduit leading from said blast stove to the stack.

.4. In a system for supplying heated combus 'llb tible gas suitable as an aid in the cracking of hydrocarbon oils, the method of operating a plurality of .hot blast stoves comprising the steps which consist in heating a given stove by burning a fuel of comparatively high calorific value while diluting the fuel as it is burned by combustion (flue) gas produced by the same or another stove in the series to thereby reduce the flame temperature, then when the stove has I reached the desired temperature, discontinuing PS the heating by cutting ofi the supply of fuel and air but continuing the admission of the flue gas until the stove is purged of free oxygen.

5. In the method according to the preceding claim, thefurther steps, when the said purging I'KO operation has been accomplished, of leading a combustible gas through said stove to heat said gas until the temperature of the stove has dropped to a predetermined temperature, discontinuing the fiow of the gas to be heated, leading off the excess combustible gas in the stove, then admitting a supply of flue gas from another stove in the series to purge the stove of combustible gas and conducting the mixture of flue and combustible gas from the stove by a separate route from that of the gases of combustion produced in the stove whereby no combustion gas ismixed with the supply of flue gas which is circulated in the other stoves.

' EMIL BLANCKEN'BURG. V5

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