US3497192A

US3497192A - Particle circulation vertical furnace

Info

Publication number: US3497192A
Application number: US730114A
Authority: US
Inventors: Michel Tamalet
Original assignee: Heurtey SA
Current assignee: Heurtey SA
Priority date: 1967-05-22
Filing date: 1968-05-17
Publication date: 1970-02-24
Anticipated expiration: 1987-02-24
Also published as: ES354124A1; DE1758386C3; BE715115A; LU56068A1; FR1547417A; DE1758386B2; DE1758386A1; SE340466B; NL6807175A; GB1189242A

Description

Feb. 24, 1970 M. TAMALET 3,497,192

PARIICLE CIRCULATION VERTICAL FURNACE Filed May 17 1968 v 3 Sheets-Sheet 1 A LIL,

Feb. 24, 1970 M. TAMALET PARTICLE CIRCULATION VERTICAL FURNACE 3 Sheets-Shee'fl 2 Filed May 1'? 1968 H l. -HHHHHII U ,M -..'...WNH -il U r2 ,/,4 w w w L. z f M roo M i M d w/ /NMU 7M um w I NWCHH. TAMALET, :ummm

Feb. 24, 1970 M. TAMALET n 3,497,192

PARTICLE CIRCULATION VERTICAL FURNACE Filed May 17 1968 5 Sheets-Sheet 3 MICHEL ml/ENTDU..

United States Patent O im. ci. F2711) 11700,- Fzsd 13/00 U.S. Cl. 263-40 10 Claims ABSTRACT oF THE DISCLOSURE This vertical furnace for applying thermal treatments to relatively long pieces held in a vertical position comprises a carefully heat-insulated mufile in which said pieces are suspended, and at the bottom of the furnace iiuidized beds for heating and cooling a heat-transfer medium consisting of solid particles injected into said mufe by means of siphons so that the particles fall by gravity and contact the pieces, and valve means for adjusting the output of said heat-transfer medium; the furnace is pivotally mounted on a hollow shaft also acting as a duct for returning the solid particles to said fluidized beds, whereby said furnace can be tilted -to a horizontal position for horizontally loading said muflle with the pieces to be treated, and chambers are provided at the top of the furnace for receiving solid particles of which the direc-t fall by gravity through shoot means into said muie is adapted to cause when necessary the rapid cooling of the pieces disposed therein.

The present invention relates to improvement in or relating to vertical furnaces of the type operated by causing therein a continuous circulation of solid particles, and its essential object consists in solving the problems arising when it is desired to apply a heat treatment such as annealing, maintaining at a predetermined temperature, hardening, etc., to pieces of relatively great length which have to be treated in the vertical position.

A furnace according to this invention comprises essentiallyz a vertical, carefully heat-insulated mufiie in which the pieces to be treated are suspended in the vertical position; means for heating and cooling a heat-transfer medium consisting of solid particles; means for raising said heated or cooled particles to the upper portion of the furnace and subsequently inject same into the muflie in which they move downwards by gravity while contacting :the pieces -to be treated, and means for adjusting the heattransfer uid output.

According to this invention the solid particles are heated or cooled in fluidized beds disposed at the bottom of said muie, said particles being raised to the upper portion and injected into the furnace by using a Siphon.

According to a specific feature of this invention, the heat-transfer fluid output is regulated by means of mechanical or pneumatic valves disposed at the lower portion of the furnace in the duets provided for returning the particles to the heating and cooling means.

According to this invention the pieces to be treated are charged into the muie from the top thereof, said'pieces being hoisted by a gantry and lowered into the furnace. According to a modified form of embodiment the loading is performed horizontally, and in this case the mule is adapted -to pivot about a hollow shaft acting at the same time as a duct for returning the particles to the heating and cooling means.

According to another feature characterising this invention, one or more chambers are provided at the upper portion of the furnace and filled with particles at the desired temperatures which are poured directly into the ice muflie in order to produce a sudden temperature drop in the pieces disposed therein, by using shoots or like devices and filling same instantaneously.

In a specific form of embodiment of the furnace of this invention, the furnace is used for performing treatments in special atmospheres; to this end, the means for heating or cooling the heat-transfer medium are constructed in a fluid-tight manner and the fluid is carried along by the atmosphere-forming gas which is constantly drawn from from the upper portion of the furnace, scrubbed and recycled,

Other features and advantages of this invention will appear as the following description -proceeds with reference to the accompanying drawing illustrating diagrammatically by way of example and not of limitation typical forms of embodiment of the invention.

In the drawing:

FIGURE l is a first fragmentary sectional diagrammatic view (upper portion) showing a first form of embodiment of the furnace of this invention;

FIGURE 2 is another fragmentary sectional diagrammatic view (lower portion) of the same furnace, this FIGURE 2 constituting the lower extension of FIGURE l when the two figures are assembled along the line AB, and

FIGURE 3 is a diagrammatic comprehensive view of the furnace according to this invention, shown only by its external contour and showing at mid-height fthe line AB along which the fragmentary FIGURES l and 2 are to be assembled.

Referring to the fragmentary FIGURES l and 2 illustrating the upper and lower portions respectively of the furnace which are adapted to be assembled along said line AB, i-t will be seen that the furnace according to this invention comprises a vertical muie 10 surrounded by a sheath 12 of heat-insulating material. In this vertical muie the pieces to be treated are disposed vertically. The drawing shows only one piece 14 but of course several pieces may be treated concurrently if desired. To avoid any distortion :these pieces 14 are suspended in the furnace through any suitable means; thus, these pieces may comprise an axial bore through which a cross member may be disposed with its ends engaging recesses formed in the walls of the muflie. At its upper portion the mufe 10 has an extension consisting of a movable sleeve 2-6 connecting the muflie to

particle delivering shoots

24, 24.

At its lower portion the furnace comprises a number of apparatus for heating or cooling a heat-transfer fluid consisting of solid particles such as sand. In the specific form of embodiment illustrated in the drawing the furnace comprises a particle heating apparatus 16 and a particle cooling apparatus 18.

Of course, the furnace according to this invention mav com-prise a plurality of heating and cooling apparatus -16 and 18. in case the pieces to be treated have to be successively heated, annealed and tempered or hardened.

The solid particles may advantageously be heated and cooled in fiudized beds.

The heated or cooled particles are raised by means of

siphons

20, 20' to the upper portion of the furnace through ducts 22, 22' respectively. Duct 22 designed for supplying heaed particles to the treatment furnace is carefully heat-insulated. The particles are injected into the furnace through the

aforesaid shoots

24, 24 and fall by gravity into the muie so as to fill same. The particle output is adjusted according to any suitable means, such as pneumaticallyor mechanically operated

valves

28, 28 disposed at the lower portion of the furnace in the ducts provided for returning the particles to the heating and

cooling apparatus

16 and 18, respectively.

According to a-modified form of embodiment, one or more chambers adapted to be filled with particles at the desired temperature may be provided in the upper portion of the furnace; those particles are introduced into the mufle directly, by gravity, in order to being about for example a sudden drop in the temperature of the pieces to be treated.

If desired, the pieces to be treated may be introduced into the mufe from the top of the furnace by removing the mufe cap; in this case the pieces are hoisted by a gantry crane and lowered into the furnace in which they are properly suspended. In the form of embodiment illustrated in the drawing the furnace is provided with means permitting the horizontal loading thereof. To this end the furnace is pivotally mounted by means of a hollow shaft 30 journalled in xed bearings carried by the base of the furnace. This hollow shaft 30 acts at the same time as a duct for exhausting the hot and cold particles and comprises to this end adequate shaft packings or rotary seals 32. The sleeve 26 is adapted to slide by using any suitable mechanical means therefor, in order to free the top portion of the muiile and permit its rotation about the hollow shaft 30 so that the muffle can be loaded in the horizontal position with the pieces to be treated.

During the heating period of the treatment cycle the particles circulate in closed-circuit conditions, with the valve 28 in its open position, from the heating apparatus 16 to the furnace proper.

To keep the pieces under constant temperature conditions, the particle circulation is stopped by closing the valve 28 so that the pieces to be treated are maintained at the temperature prevailing in the mufe, i.e. in the medium consituted by the hot particles.

To obtain an accelerated cooling the hot particles are discharged from the mufe and a stream of cold particles 18 is created..

It will be noted that the adjustment temperature of the furnace is the temperature of the particles introduced into it. It is thus clear that with the device according to this invention it is possible to perform in the same furnace, without displacing the pieces to be treated, a heating step followed or not by the maintaining of the same temperature and by a hardening step or .other heat treatment. The number of particle cooling and heating apparatus, as well as the number of apparatus for feeding these particles to the mule, may be increased at will, for example if the pieces to be treated have to be submitted to a cronsiderable number of successive heating, annealing, isothermal, hardening steps and the like.

It is likewise relatively easy to perform an isothermal hardening treatment since it is only necessary to this end to complete the device with a separate particle heating apparatus adjusted at the selected temperature.

The furnace according to this invention is also suitable for performing treatments in a given atmosphere. In this case the apparatus for heating and cooling the particles are constructed in a gas-tight manner and the particles are entrained through the siphons or like means by a gas constituting the desired atmosphere. This gas is then sucked at 34 from the upper portion of the furnace, scrubbed and recycled.

To produce a slow heating of the pieces to be treated in the furnace, a relatively small quantity of particles are injected into the muifle but these particles are removed immediately thereafter so that they contact only rapidly the pieces to be treated.

The furnace according to this invention is characterized inter alia by the following advantageous features:

A high rate of heat transfer between the particles and the pieces to be treated; by using a particle circulation the heating time is reduced significantly and very rapid hardening treatments can be performed.

The temperature is distributed throughout the furnace with a gerat homogeneity, since the heat-transfer particles constitute a mass of great heat capacity with respect to the assembly consisting of the furnace proper and the pieces to be treated therein.

The possibility of performing successively, in the same furnace, and without displacing the pieces to be treated, a heating step followed by a hardening step, and possibly by other treatments, possibly in a special atmosphere.

The furnace according to this invention may be used for applying not only heat treatments to any pieces requiring a vertical position in the furnace during their treatment, but also continuous heat treatments to vertically fed products such as sheet metals, strips, tapes, wires or rods.

Although the present invention has been described in conjunction with preferred embodiments, it is to be understood that modifications and variaitons may be resorted to without departing from the spirit and scope of the invention, as those skilled in the art will readily understand.

What is claimed is:

1. A vertical furnace of the particle-circulation type, which comprises a carefully heat-insulated vertical muffle, means for suspending in a vertical position the pieces to be treated in said mufe, fluidized bed means in the lower portion of said furnace for heating and cooling a heat transfer medium consisting of solid particles, siphon means for producing an ascending stream of said particles in the heated or cooled state towards the top of the furnace and injecting said particles into said muifle by gravity so that they contact the pieces to be treated during their fall, and means for adjusting the output of said heat-transfer medium.

2. A vertical furnace of the particle-circulation type, which comprises a carefully heat-insulated vertical muie, means for suspending in a vertical position the pieces to be treated in said muflie, fluidized bed means in the lower portion of said furnace for heating and cooling a heat transfer medium consisting of solid particles, Siphon means for producing an ascending stream of said particles in the heated or cooled state towards the top of the furnace and injecting said particles into said muffle by gravity so that they contact the pieces to be treated during their fall, and pneumatically operated valve means for adjusting the output of said medium7 which are disposed at the lower portion of the furnace, in ducts arranged for returning said particles to said heating and coolin g means.

3. A vertical furnace of the particle-circulation type, which comprises a carefully heat-insulated vertical muflie, means for suspending in a vertical position the pieces to be treated in said muffle, uidized bed means 1n the lower portion of said furnace for heating and cooling a heat transfer medium consisting of solid particles, siphon means for producing an ascending stream Of said particles in the heated or cooled state towards the top of the furnace and injecting said particles into said muifle by gravity so that they contact the pieces to be treated during their fall, and mechanically operated valve means for adjusting the output of said medium, which are disposed at the lower portion of the furnace in ducts arranged for returning said particles to Said heating and cooling means.

4. A vertical furnace as set forth in claim 3, wherein the pieces to be treated are adapted to be introduced into said muie from the top thereof.

5. A vertical furnace as set forth in claim 3, wherein the pieces to be treated are adapted to be introduced into said mufe from the top thereof.

6. A vertical furnace as set forth in claim 3, wherein said furnace is pivotally mounted on a horizontal hollow shaft permitting on the one hand of tilting the furnace to a horizontal position for introducing the pieces to be treated in a horizontal position and on the other hand of acting as a duct for returning the solid particles constituting said heat-transfer medium to said heating and cooling means.

7. A vertical furnace as set forth in claim 3, which comprises at its upper portion a chamber adapted to be filled with solid particles at the desired temperature, and shoot means connecting said chamber directly to said mufe, whereby the temperature of the pieces to be treated can be reduced very rapidly by allowing said par ticles to fall into said muflle.

8. A vertical furnace as set forth in claim 3, which comprises at its upper portion a plurality of chambers adapted to be filled with solid :particles at the desired temperature, and shoot means connecting said chambers directly to said mue, whereby the temperature of the pieces to be treated can be reduced very rapidly by allowing said particles to fall into said mule.

9. A furnace as set forth in claim 6, wherein rotary seals are provided at suitable locations on said horizontal hollow shaft for imparting the necessary fluid-tightness to said duct-forming shaft.

References Cited UNITED STATES PATENTS 3,350,915 11/1967 Stafn 165--104 FOREIGN PATENTS 842,505 7/ 1960 Great Britain.

JOHN J. CAMBY, Primary Examiner U.S. C1. X.R. 165-104