US3595540A

US3595540A - Ball heater-equilibrator system

Info

Publication number: US3595540A
Application number: US870378A
Authority: US
Inventors: John A Whitcombe
Original assignee: Oil Shale Corp
Current assignee: Oil Shale Corp
Priority date: 1969-09-02
Filing date: 1969-09-02
Publication date: 1971-07-27
Anticipated expiration: 1988-07-27
Also published as: ZA705856B

Abstract

A ball heater and ball temperature equilibrator system wherein the balls to be heated and the hot flue gas heating medium are cocurrently flowed through the ball heater to raise the temperature of the balls to varying higher ball temperatures and wherein the balls having varying higher ball temperatures have their temperature brought to substantial equilibrium by flowing, preferably cocurrently, the nonuniformly heated balls and flue gas from the ball heater through the ball temperature equilibration chamber having ball intermixing means therein.

Description

United States Patent 2,949,347 8/1960 Van Pooi 23/288 FOREIGN PATENTS 212,671 3/1924 Great Britain 263/19 Primary Examiner- Edward G. Favors Attorney-Brumbaugh Graves, Donohue & Raymond ABSTRACT: A ball heater and ball temperature equilibrator system wherein the balls to be heated and the hot flue gas heating medium are cocurrentiy flowed through the ball heater to raise the temperature of the balls to varying higher bail temperatures and wherein the balls having varying higher ball temperatures have their temperature brought to substantial equilibrium by flowing, preferably cocurrently, the nonuniformly heated balls and flue gas from the ball heater through the ball temperature equilibration chamber having ball intermixing means therein.

BALLS PATENTED JUL2 7:971

BALLS BALLS VENT GAS FLUE GAS q com o, Weed do 0 FLUE GAS INVENTOR. 1 A. WHITCOMBE his A T TORNEYS.

BALL HEATER-EQUILIBRATOR SYSTEM The present invention relates to a ball heater'and ball temperature equilibration system.

Solid heat exchange bodies, such as metallic or ceramic balls or pebbles, are used in a variety of processes for heating material to be processed.

Exemplary of such processes are those wherein oil shale or other solid hydrocarbonaceous materials are pyrolyzed by means of hotter heat exchange bodies to extract hydrocarbonaceous material therefrom. After the heat exchange bodies have exchanged their heat by contact with the material to be heated thereby, the heat exchange bodies must have their temperature brought back to an elevated temperature so that they can be economically reused or recycled for the processing of further material.

A variety of heaters have been proposed heretofore for reheating and/or regenerating solid heat-carrying bodies such as balls, pebbles, catalyst and the like. The typical of such devices are those disclosed in US. Pat. Nos. 2,534,625; 2,609,332; 2,626,794; 2,735,880; and 2,851,403. These known heaters, however, are deficient in a number of respects. For example, in those prior devices utilizing countercurrent heating techniques, the pebbles are reheated by passing a flue gas in countercurrent flow to the pebbles. Such cduntercurrent heating apparatus does not efficiently utilize the flue gases mainly because of temperature restrictions imposed thereon on account of the materials of construction. Both cocurrent and countercurrent heaters require extensive internal devices located in the bottom zone of the heater to obtain relatively uniform cross-sectional distribution of flue gas flow and pebble flow. With cocurrent flow the internal devices are not exposed to the hot flue gases brought into the heater to heat the pebbles. Thus, the internal devices can be of relatively inexpensive construction while still utilizing very high temperature flue gas without significantly increasing the cost of the heater. However, I have found that even with well designed internal devices to obtain good distribution of pebble and gas flow, such apparatus still fails to provide heat-carrying bodies that are heated to relatively uniform temperatures. In the cocurrent type heater there are invariably nonuniformly heated bodies, primarily because of varying residence times of the solid bodies on the upper surface of the bed. It is the nonuniformity of heating that the present invention seeks to alleviate.

The requirements for uniformly heated heat-carrying bodies is of significant economic importance because of the mechanical stresses placed on the body resulting from alternate heating and cooling operations. in particular, when using ceramic heat-carrying bodies, each ceramic composition possesses certain definite thermal shock limits. When the limits are exceeded, particularly on cooling, the ceramic body rapidly disintegrates. For example, I have found in the processing of oil shale that for a ceramic ball of a particular composition and size, the maximum allowable thermal shock upon cooling was a temperature differential of about 850 F. That is, for example, when balls having an average mean temperature of about l,250 F. are contacted with oil shale preheated to about 500 F., the balls are subjected to a temperature differential of about 750 F. upon cooling. This thermal shock level of 750 F. will not be destructive if all of the balls are initially at a temperature of about l,250 F. lf, however, the balls were not heated uniformly, that portion of the balls above l,350 F. will receive a shock of greater than 850 F. and will be subject to fracture and breaking. It is then imperative that the ceramic bodies be brought to a relatively uniform temperature so as to avoid high-breakage rates which result in unfeasible economics.

Some of the prior ball heating apparatus, while equipped with a ball temperature equilibration chamber, effect ball temperature equilibration either by allowing the balls of uneven higher temperature to move in contact with one another in a ball bed or by the passage of an additional heating gas through the ball temperature equilibration chamber. However, the use of an additional heating gas to effect ball temperature equilibration requires substantial expenditures for equipment to heat and control the temperature and pressure of the additional heating gas. Moreover, it is difficult to regulate the temperature and pressure of the additional heating gas to insure effective temperature equilibration and flow of the heating gas through the ball temperature equilibration chamber.

It is, therefore, an object of the present invention to provide a ball heater and ball temperature equilibrator system which will not suffer from the above disadvantages of the prior apparatus.

it is further object of the present invention to provide a ball heater and ball temperature equilibrator system which is more efficient and economical to construct and operate.

A still further object of the invention is to provide a ball heater and ball temperature equilibrator system which can be used satisfactorily for the heating of ceramic balls withou causing undue thermal stresses therein.

A still further object of the present invention is to provide a method of equalizing the temperatures of heat exchange bodies which initially possessed substantial divergent temperatures.

in general, a method and apparatus is provided for equalizing the temperature of heat-carrying bodies previously heated to temperatures which vary significantly. Broadly, the method involves introducing solid heat-carrying bodies of varying or nonuniform temperatures into a temperature equalization chamber, introducing flue gas having the average mean temperature of the heated heat-carrying bodies into the temperature equalization chamber, intimately intermixing the heatcarrying bodies and the temperature equilizing gas while gravitating the heat-carrying bodies through the temperature equalization chamber to provide flue gas and heat-carrying bodies at a substantially uniform temperature, and thereafter withdrawing the flue gas and heat-carrying bodies from the equilibration chamber. The uniformly heated bodies may thereafter be passed to a retort or other reaction chamber for use therein. The solid heat-carrying body heater and solid heat-carrying body temperature equilibrator system of the present invention comprises means for the cocurrent, rather than countercurrent, flow of hot flue gas and solid heat-carrying bodies through the heater and means for flowing, preferably cocurrently, the heated solid heat-carrying bodies and discharge flue gas from the heater through the solid heatcarrying body temperature equilibrator.

The system or apparatus of the invention will be further described in connection with the accompanying drawing which is a cross-sectional elevational view of the preferred embodiment thereof.

Referring now to the drawing, the ball heater-ball temperature equilibrator system comprises a gravity fed, cocurrently fired, ball heater 1 and a ball temperature equilibration chamber 2. The equilibration chamber units are four in number spaced horizontally from one another at approximately (only two of each of these units are shown in the drawing).

The ball heater 1 comprises a combustion chamber 3 having at the top thereof a fuel line 5 and an air line 6 connected to a burner 7 for the generation of the hot flue gases. Four hot flue gas outlets 8 are at the base thereof and at right angles to one another (only two are shown in the drawing). Each of the four flue gas outlets 8 is connected respectively to the ball-heating chamber 9.

The ball-heating chamber 9 is provided thereabove will a ball surge vessel 10 of annular design for the receipt of balls to be reheated. The ball surge vessel 10 is connected at the base thereof to the top of the ball heating chamber 9 by a plurality of ball conduits 11. The lower portion of the ball surge vessel 10 has vent gas outlets 12 therein beneath vent gas collector channels 13.

The ball-heating chamber has a plurality of ball outlet conduits 1Q at-the base'the reof whichextend downwardly from ball bed support plates 15 having orifices corresponding with the ball outlet conduits 14. Within the ball-heating chamber 9 is a plurality of circumferential flue gas collector channels 16 for withdrawing the hot flue gas from the ball-heating chamber 9 via a plurality of flue gas conduits 17 which extend from beneath the channels 16 to orifices in the ball bed support plates 15.

The four ball temperature equilibration chambers 2 (only two are shown in the drawing) are arranged horizontally at right angles to one another. Each ball temperature equilibration chambers 2 has beneath the ball inlet conduits 14 a plurality of baffle plates 18 for commingling the downwardly flowing heated balls. The tapered base 19 of each ball temperature equilibration chamber 2 is provided with a reheated ball outlet conduit 20 connected to a common ball transport conduit 21 for passage of the reheated balls to a heat exchanger, such as an oil shale pyrolyzer or retort.

The flue gas flowing downwardly through flue gas conduits l7 flows out of the heating apparatus through flue gas outlet zone 22 and thence to the flue gas collection zone 23, and by flowing downward through the equilibration chambers 2 for ball temperature equilibration purposes therein and thence under downwardly extending circumferential right angle channel members 24 mounted on the walls of each of the ball temperature equilibration chambers 2 for disengaging the flue gas therefrom, and thence to flue gas outlet conduits 25. The relative amount of the gases that leave the heating apparatus through conduit 26 compared to that leaving through the equilibration chamber exit pipes 25 is controlled by control of the pressures at these two points. The flue gas collection zone 23 is connected to a major flue gas outlet conduit 26 for withdrawing most of the flue gas for other use, such as in a raw oil shale preheat lift pipe.

The balls or pebbles flow through the apparatus in the following manner. Balls to be reheated are fed into the top of the ball surge vessel 10. The balls then pass by gravity from the base thereof through ball outlet conduits l1 and into ballheating chamber 9. The balls gradually pass downwardly through the ball-heating chamber 9 and exit therefrom through the plurality of ball outlet conduits 14 and then into ball temperature equilibration chambers 2. Therein the balls are intermixed by baffle plates 18 before passing from the tapered base 19 of the ball temperature equilibrators 2 through outlet conduits 20 and common ball transport conduit 21.

The passage of the flue gas through the preferred embodiment of the apparatus of the invention shown in the drawing occurs in the following manner. Fuel and air fed from lines and 6 respectively are burned in burner 7 to produce hot flue gas. The hot flue gas passes from the combustion chamber 3 via the hot flue gas outlet 8 into the top of ball-heating chamber 9. The hot flue gas descends in contact with the balls within the ball-heating chamber 9 and then passes via flue gas collector channels 16, flue gas outlet conduits l7 and flue gas outlet zone 22 partly into the ball temperature equilibration chambers 2 and partly into the flue gas collection zone 23. (A small portion of the flue gas escapes from the ball-heating chamber 9 by ascending through the ball conduits 11 and out of the ball surge vessel via vent gas collector channels 13 and vent gas outlets 12.)The flue gas is withdrawn from the flue gas collection zone 23 via major flue gas outlet conduit 26. After passage through the balls within the ball temperature equilibration chambers 2, the flue gas exits therefrom via the channel members 24 and the flue gas outlet conduits 25.

ln operation of the apparatus of the invention, balls or pebbles having a temperature of from about 850 F. to about 950 F. are fed into the ball surge vessel 10. The balls pass downwardly therefrom via conduits 11 and into the ball-heating chamber 9.

Fuel and air are fed via

lines

5 and 6 respectively into the burner 7 within combustion chamber 3 where the fuel is burned to produce hot flue gas having a temperature of from about 2,300 F. to about 3,000 F. The hot flue gas is passed from the combustion chamber 3 via outlets 8 and into the ballheating chamber 9. The hot flue gas in contact with the balls in the ball-heating chamber 9 raises the temperature of the balls to varying temperatures such that the coldest balls generally have a temperature of about 950 F. and the hottest balls generally have a temperature of about l,800 F.

The nonuniformly heated balls are withdrawn from the ballheating chamber 9 via ball outlet conduits 14 and fed intothe ball temperature equilibration chambers 2. The flue gas withdrawn from the ball-heating chamber 9 via flue gas collector channels 16 and flue gas outlet conduits 17 and into the flue gas collection zone 23 has a temperature generally of about l,275 F. in view of the heat exchange between the hot flue gas and the balls in the ball-heating chamber 9.

The major portion of the flue gas is withdrawn from the flue gas collection zone 23 via flue gas outlet conduit 26 for further use, such as in a raw oil shale preheat lift pipe. The remainder of the flue gas having a temperature of about 1,275 F. passes through the balls in the ball temperature equilibration chambers 2 in a cocurrent manner to effect ball temperature equilibration. The flue gas is withdrawn from the ball temperature equilibration chambers 2 via channel members 24 and flue gas outlet conduits 25 wherein the flue gas has a temperature of about l,275 F.

The balls within the ball temperature equilibration chambers 2 have their temperature substantially equalized so that the hottest balls have a temperature of approximately l,400 F. with the average temperature of the balls being about l,275 F. The substantially uniformly heated balls are withdrawn from the ball temperature equilibrators 2 via

conduits

20 and 21 and used as heat exchange media in any desired process, such as in the pyrolysis of oil shale.

The apparatus of the invention can be modified, where desired, so as to feed the flue gas from the ball heater through the ball temperature equilibrator in countercurrent flow to the descending balls within the ball temperature equilibrator by providing each bail temperature equilibrator 2 with a horizontal plate over the top thereof having perforations therein only for the entry of ball conduits 14, by providing a line from flue gas outlet 26 to connect with conduits 25 which then become flue gas inlet pipes, and adding flue gas outlet conduits located just below the aforesaid added horizontal plate.

In view of the above discussion of the apparatus of the invention, it will be clear that it provides a ball heater and ball temperature equilibrator system which is highly efficient and economical to construct and operate. Moreover, in view of the cocurrent flow of the balls and flue gas, the system utilizes the flue gas very efficiently. For example, in a similar but countercurrent ball heater, fuel gas enters the heater at l,800 F. to raise the cold ball temperature from 900 F. (gas out) to l,275 F. resulting in a net gas temperature differential of 900 F whereas, in the cocurrent ball heater of the invention, gas enters at 2,700 F. to raise the cold ball temperature from 900 F. (gas out) resulting in a net gas temperature differential of l,425 F. In order to operate at the lower prior art countercurrent ball temperatures, temperature, substantially more flue gas is required, thereby increasing the size of the ball heater itself as well as the attendant equipment.

As noted above, the cocurrent ball heater system of the invention makes it possible to utilize efficiently the higher flue gas temperature of 2,700 F. or greater without damaging either the ceramic balls or the internal parts of the ball heater. For example, in a countercurrent type ball heater the flue gas usually enters the bottom of the ball heater in the area where the balls are discharged, which is also the region of maximum overheating. Consequently, the flue gas inlet temperature must be limited to approximately the hot ball temperature, otherwise, some of the balls will be heated to the flame temperature while others will remain underheated. Under such conditions, a uniformly heated ball stream is not readily obtainable. FUrthermore, because of the hot gas inlet location, extreme caution must be exercised in the design, construction and operation of any countercurrent ball heater which has baffles or gas distribution devices located in that vicinity to prevent serious thermal damage thereto. However, as located in that pointed out, in the eocurrent ball heater system of the invention, substantial economies are realized since it is possible to locate the baffle arrangement down in the ball bed at a point of lower temperature. It will be noted that the circumferential flue gas collector channels 16 serve as baffles for intermittently mixing the balls. The hottest flame temperature is above the ball bed. The balls that are overheated have the entire length of the ball heater to soak and mix. Since the ball heater flue gas outlet temperature is approximately that of the average mean hot ball temperature, i.e., 1 ,275 F. difficult ball heater and baffle designs which incorporate exotic materials are not required.

It will also be noted that the ball heater and ball temperature equilibrator of the invention does not utilize any additional heating gas in the ball temperature equilibrator but rather the ball temperature equilibrator utilizes the flue gas from the ball heater. Therefore, the flue gas is available in the ball temperature equilibrator at precisely the proper temperature and pressure to insure effective temperature equilibration and flow of flue gas through the bed. Moreover, the utilization of the flue gas from the ball heater in the ball temperature equilibrator, rather than using an additional heating gas in the ball temperature equilibrator, eliminates the requirement for a substantial expenditure for equipment to heat and control the temperature and pressure of additional heating gas.

It will be appreciated that various modifications and changes can be made in the apparatus of the invention in addition to those suggested above by those skilled in the art without departing from the essence of the invention. Therefore, the invention is to be limited only within the scope of the appended claims.

What I claim is:

1. In an apparatus for the heating of solid heat-carrying bodies to a substantially uniform temperature having a combustion chamber for the generation of hot flue gas, a heater chamber connected to said combustion chamber for the heating of cool solid heat-carrying bodies fed gravitationally therethrough by said hot flue gas to varying higher temperatures and a solid heat-carrying body temperature equilibration chamber containing solid heat-carrying body intermixing means therein and connected to said heater chamber, the improvement which comprises means for cocurrently flowing flue gas and solid heat-carrying bodies through said heater and means for flowing said heater discharge flue gas and solid heat-carrying bodies through said solid heat-carrying body temperature equilibration chamber.

2. In an apparatus for the heating of heat-carrying bodies to a substantially uniform temperature having a combustion chamber for the generation of hot flue gas, a heater chamber connected to said combustion chamber for the heating of cool solid heat-carrying bodies fed gravitationally therethrough by said hot flue gas to varying higher temperatures and a solid heat-carrying body temperature equilibration chamber containing solid heat-carrying body intermixing means therein and connected to said heater chamber, the improvement which comprises means for cocurrently flowing flue gas and solid heat-carrying bodies through said heater and means for cocurrently flowing said heater discharge flue gas and solid heat-carrying bodies through said solid heat-carrying body temperature equilibration chamber.

, 3. In a process for heating solid heat-carrying bodies wherein said bodies are introduced into a heating chamber and gravitated downwardly therethrough while contacting hot flue gas therein to heat said bodies to varying higher temperatures, and wherein the nonuniformly heated bodies are withdrawn from said heating chamber and fed to a solid heatcarrying body temperature equalization chamber, the improvement which comprises intimately intermixing said nonuniformly heated bodies while contacting said bodies with the discharge flue gas from said heating chamber, withdrawing substantially uniformly heated solid heat-carryin bodies from said temperature equalization chamber, and wit drawing flue gas from said temperature equalization chamber at a temperature which is substantially that of said uniformly heated bodies.

2 3 5 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,595,5 Dated y 7, 97

John A. Whitcombe Inventor(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

fi Column 1, line 53, "the" should be these --5 line 69,

"high-breakage" should be high breakage Column 2,

line 1 after the word "is" and before "further" insert a --3 line 67, "will" should be with Column line 56, after "F." and before "(gas out)", insert to 1275F. line 58, after 'ball" insert heater --5 line 58, delete 'temperature," Column 5,

lines

2 and 3, delete "located in that" and insert previously Signed and sealed this 8th day of February 1972.

(SEAL) Attest: WM

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents

Claims

1. In an apparatus for the heating of solid heat-carrying bodies to a substantially uniform temperature having a combustion chamber for the generation of hot flue gas, a heater chamber connected to said combustion chamber for the heating of cool solid heat-carrying bodies fed gravitationally therethrough by said hot flue gas to varying higher temperatures and a solid heat-carrying body temperature equilibration chamber containing solid heat-carrying body intermixing means therein and connected to said heater chamber, the improvement which comprises means for cocurrently flowing flue gas and solid heat-carrying bodies through said heater and means for flowing said heater discharge flue gas and solid heat-carrying bodies through said solid heatcarrying body temperature equilibration chamber.

3. In a process for heating solid heat-carrying bodies wherein said bodies are introduced into a heating chamber and gravitated downwardly therethrough while contacting hot flue gas therein to heat said bodies to varying higher temperatures, and wherein the nonuniformly heated bodies are withdrawn from said heating chamber and fed to a solid heat-carrying body temperature equalization chamber, the improvement which comprises intimately intermixing said nonuniformly heated bodies while contacting said bodies with the discharge flue gas from said heating chamber, withdrawing substantially uniformly heated solid heat-carrying bodies from said temperature equalization chamber, and withdrawing flue gas from said temperature equalization chamber at a temperature which is substantially that of said uniformly heated bodies.