US1690048A - Rotary kiln and furnace - Google Patents

Description

Oct. 30, 1928.

J. H. BENTLEY v ROTARY KILN AND FURNACE 2 Sheets-Sheet Filed- Sept. 9, 1926 J. H. BENTLEY ROTARY KILN AND FURNACE Oct. 30, 1928.

Filed Sept. .9, 1926 ZSheetS-Sheet' 6 R. O w w m Patented Oct. 30, 1928.

UNITED STATES JOHN HENRY BENTLEY, 0F MISTERTON, ENGLAND.

ROTARY KILIN' AND Application filed September 9, 1926, Serial No'.

This invention relates to rotary kilns and furnaces of the type in which the heat extracted in cooling the material is used to preheat the air and fuel supplied to the combustion zone of the kiln or furnace, the object of the invention being to provide improved means for obtaining this recuperatorefi'ect and to increase the output and reduce the fuel consumption.

In kilns used for burning cement materials there is usually a drying or preheating zone at the feed end followed by a calcining zone and a sintering zone where combustion of the fuel takes place adjacent to the discharge end. It is known to provide a preliminary cooling chamber of greater diameter than the sintering zone between that zone and a central discharge orifice and according to the present invention lifting ducts are fitted at the end of such a cooling chamber and formed with scoop-like openings. at its circumference. A delivery cone, provided by a conical or inclined guide closes the inner ends ofrthe lifting ducts to the interior of the kiln and opens them to the exterior, and a recuperator chamber is furnished below the discharge orifice connected thereto by a pipe or cowl having a packed joint around the orifice. Cascaders may be provided in the cooling chamber.

The recuperator chamber preferably contains an inner cellsurmounted by a conical spreader (which may be fitted with spikes) and the chamber is formed with a hopper-like base. Cooling air is supplied to the cell and issues therefrom through ports into an annular passage between cell and chamber, and if desired an encased. conveyor may be provided below the base of the recuperator chamber, cooling air being supplied to the chamber also through the conveyor casing.

Fuel is preferably blown into the kiln by a fan or blower deriving its air from the recuperator chamber and connected to a pipe extending co-axially through the delivery cone and through the preliminary cooling chamber. Secondary combustion air passes into the kiln from the recuperator chamber through the lifting ducts which may be provided with apertures through their inner walls to deliver this air nearer to the centre of the preliminary cooling chamber. A renewable sleeve is conveniently fitted on the fuel pipe adjacent to the delivery cone to protect it from damage by the falling clinker.

In the accompanying drawing I other by radial fins 11 of the being a continuation of one or 134,545, and in Great Britain J'anuai'y 8, 1926.

Figure 1 is a longitudinal section elevation of the delivery end of a rotary kiln or furnace. according to the present invention.

Flgure 2 is a half end view and transverse section of Figure 1.

Like reference numerals indicate like parts throughout the drawing.

The drying or preheating and calcining zones of the kiln are not illustrated, Figure 1 showing the end of the sintering zone 3. Beyond this zone the kiln is continued with a somewhat greater diameter to provide a prehminary cooling chamber-4 which is closed at the end by a suitable cover 5 having a central discharge orifice as shown in Figure 1 and being fitted with a circular track 6 supported on rollers 7.

Gascaders 8 are shown inside the preliminary cooling chamber 4 arranged to lift the material therein as they revolve with the kiln, preferably only to such a height that the view of the operator is notobscured through the upper portion. The cascaders 8 do not extend to the extreme end of the preliminary cooling chamber 4, and in this cylindrical end portion thereof is arranged a series of hollow lifting ducts 9 rotating with the chamber. The lifting ducts 9 are formed with scoop-like openings at the circumference of the chamber 4 and extend therefrom to a delivery cone 10 at the central discharge orifice, the delivery cone 10 comprising conical or inclined guides closing the inner ends of the lifting ducts 9 to the interior of the kiln and opening them to the exterior.

The hollow lifting ducts 9 may be radial to the cooling chamber 4 as shown in the sectional half of Figure 2 or they may be curved at their outer ends as shown in dotted lines in the left-hand half of Figure 2. They may either be radial or tangential or otherwise disposed in relation to the delivery cone 10. The openings of the lifting ducts 9 to the delivery cone 10 are separated from one ane, these fins 1 both of the side walls of the lifting ducts or separate therefrom as may be desired.

A stationary recuperator chamber 12 is disposed at a lower level than the preliminary 106 cooling chamber 4, below its central discharge orifice, and is connected to the latter by a suitable -ipe or cowl 13 having a packed joint as in icated at 14 around the delivery orifice, the packing being such as to allow for the 1 expansion and contraction of the kiln as well as for its rotation.

The recuperator chamber 12 contains an inner cell 15 carried by girders 16 and surmounted by a conical spreader 17 which may be fitted with pointed spikes 18, the spreader being disposed in the path of material falling from the delivery cone 10 through the connecting pipe 13. Below the cell 15 the recuperator chamber is formed with a hopperlike base 19 by means of which the material is delivered through a suitable valve or damper 20 to a conveyor 21 or to an elevator, wagons or other suitable means of transport.

Cold air is supplied to the inner cell 15 by means of a blower or fan 22 through a pipe 23 and passes through ports or holes 24 in the lower portion of the cell into anannular space 25 between the cell 15 and walls of the recuperator chamber 12 which is preferably covered with a suitable heat insulating material (not illustrated). If desired a branch 26 from the fan pipe 23 may be connected to a casing 27 enclosing the conveyor 21 transporting the material from the base of the recu rator chamber 12, such air passing into the chamber through the valve 20.

The coal dust or other fuel is supplied through a pipe 28 and is blown into the kiln by a fan or blower 29 deriving its air supply from the recuperator chamber 12 and connected to a pipe 30 which extends across the connecting pipe 13, through the delivery cone 10 with which it is co-axial and through the centre of the preliminary cooling chamber 4 so that the fuel is burnt in the sintering zone 3. A renewable sleeve 31 is referably fitted on the pipe 30 adjacent to t e delivery cone 10 to protect it from damage due tothe material falling thereon.

In operation the material may be treated in the rotary kiln as usual, but preferably its passage therethrough is retarded by conical portions as described in my specification No. 591 of 1926. On leaving the sintering zone 3 the material is cascaded in the preliminary cooling chamber 4 and gives up a portion of its heat to the air passing therethrough. On arrivin at the extreme end it is lifted by the hol ow ducts 9 and delivered on to the discharge cone 10 whence it passes into the recuperator chamber 12 falling through the annular passage 25 provided by the inner cell 15 and being broken by the spikes 18 and the spreader 17. During this fall it is meeting the upward stream of air from the interior of the cell 15 and from the base 19, and this air is thus heated and delivered into the preliminary cooling chamber 4 through the hollow lifting ducts 9 whence it passes into the kiln to 'provide the secondary air for the combustion of the fuel, primary combustion air, of course, being derived also from the coolin chamber 12 and the amounts being contro ed by dampers or throttle valves 32.

If desired the hollow lifting ducts 9 may be formed with apertures 33 for delivering the air nearer to the centre of the preliminary cooling chamber 4;.

WVhat I claim is 1. In a rotary kiln or furnace having a preliminary cooling chamber between the sintering zone and a central discharge orifice the combination with lifting duct-s at the end of the cooling chamber having scoop-like openings at its circumference, of a delivery cone provided by a conical or inclined guide closing their inner ends to the interior of the kiln and opening them to the exterior, substantially as specified.

2. In a rotary kiln or furnace having a preliminary cooling chamber between the sintering zone and a central discharge orifice the combination with cascaders in the cooling chamber, of lifting ducts at the end of the cooling chamber having scoop-like openings at its circumference, and a delivery cone provided by a conical or inclined guide closing their inner ends to the interior of the kiln and opening them to the exterior, substantially as specified.

3. In a rotary kiln or furnace having a preliminary cooling chamber between the sintering zone and a central discharge orifice the combination with lifting ducts at the end of the cooling chamber having scoop-lilac openings at its circumference, of a delivery cone provided by a conical or inclined guide closing their inner ends to the interior of the kiln and opening them to the exterior and a recuperator chamber below the discharge orifice connected thereto by a pipe or cowl having a packed joint around the discharge orifice, substantially as specified.

4. The combination with a rotary kiln or furnace having a central discharge orifice of a recuperator chamber below such orifice connected thereto by a substantially gas tight passage and containing an inner hollow cell surmounted by a conical spreader with an annular passage between cell and chamber extending to a hopper-like base of the chamber, means for supplying cooling air to the cell and ports putting the interior of the cell into communication with such annular passage, substantially as specified.

5. The combination with a rotary kiln or furnace having a central discharge orifice of a recuperator chamber below such orifice connected thereto by a substantially gas tight passage and containing an inner hollow cell surmounted by a conical spreader with an annular passage between cell and chamber extending to a hopper-like base of the chamber, means for supplying cooling air to the cell, ports putting the interior of the cell into communication with such annular passage, an encased conveyor below the base of the chamber, a valve providing communication between the said base and the conveyor an means for supplying cooling air to the chamber through the conveyor casing, substantially as specified.

6. In a rotary kiln oriurnace having a preliminary cooling chamber between the sinterin zone and a central discharge orifice, the coin ination with cascaders in the cooling chamber, lifting ducts at the end of the cooling chamber having scoop-like openings at its circumference, a delivery cone provided by a conical or inclined guide closing their inner ends to the interior of the kiln and opening them to the exterior, a r'ecuperator chamber below the discharge orifice connected thereto by a pipe or cowl having a acked joint around the dischar e orifice, a ollow cell surmounted by a conical spreader inside the chamber with an annular passage between cell and chamber extendingtoahopperlike base of the chamber, means for suppl ing coolin air to the cell, ports putting t e interior 0 the cell into communication with such annular p e, an encased conveyor below the base of the chamber, a valve providin communication between the said base and e conveyor, means for supplying cooling air to the chamber through the conveyor casin a fan deriving air from the recuperator c amber, a pipe connected to the fan and extendin co-axially through the delivery cone an through the preliminary cooling chamber and a renewable sleeve on such pipe adjacent to the delivery cone, substantially as specified.

In testimony whereof I hereunto afiix my signature.

JOHN HENRY BENTLY.

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