GB2190485A - Heat exchanger - Google Patents

Abstract

A heat exchanger for heating fluid particulate material comprising a heating chamber (11), heating means associated with the heating chamber, a hopper (14) mounted above the heating chamber, a delivery chamber (17) located below the heating chamber, a set of flow passageways (16) extending through the heating chamber between the hopper and delivery chamber, said delivery chamber (17) having an outlet (18) at its lower portion.The heat exchanger can used in calcining, drying, effecting endothermic reactions. <IMAGE>

Description

SPECIFICATION Heat exchanger This invention relates to a heat exchanger and in particular a heat exchanger which can be used to treat materials forthe purpose of calcining, drying, effecting endothermic reactions and the like.

It is an object of the invention to ensure that material while undergoing the desired heating action is substantially isolated from the atmosphere.

In one form the invention resides in a heat exchanger for heating particulate material comprising a heating chamber, heating means associated with the heating chamber, a hopper mounted above the heating chamber, a delivery chamber located belowthe heating chamber, a set of flow passageways extending through the heating chamber between the hopper and delivery chamber, said delivery chamber having an outlet at its lower portion.

According to a further preferred feature of the invention cooling means are provided between the heating chamberandthe hopper.

According to a further preferred feature ofthe invention an injection means is provided at said outlet, said injection means being connected to a source of cooling fluid for providing a metered flow of cooling fluidto the material flowing from the delivery chamber.

According to afurther preferredfeature ofthe invention said passageways comprise tubes sealingly received in the iowerwall ofthe hopper.

According to a preferred feature of the invention means are provided for injecting a gaseous fluid into the contents ofthe hopper.

According to a preferred feature of the previous feature the gaseous fluid is at ambienttemperature.

The invention will be morefullyunderstood inthe light of the following description of one specific embodiment. The description is made with reference to the accompanying drawings ofwhich: Figure lisa part sectional elevation of a heat exchanger according to the embodiment; Figure2 is a plan view ofthe heat exchanger of Figure 1 along line 2-2; Figure 3 is an illustrationoftheform of mounting forthe heat exchangertubes in the hopper; and Figure4is an enlarged sectional elevation of the cooling fluid injection means in the outlet ofthe heat exchanger.

The embodiment ofthe invention is particularly directed to a heat exchangerforthe drying and reactivation of carbon used in the carbon-in-pulp processing of ores. Such carbon is usually delivered to the heat exchanger with a very high water content for reactivation and dewatering. In addition it is necessary that during the reactivation process that the carbon when being heated is isolated from the atmosphere to prevent oxidation.

The heat exchanger ofthe embodiment comprises a substantially cylindrical heating chamber 11 having insulatedsidewalls 12anda burner nozzle directed tangentially into the heating chamber through a port 13 provided towards the lower end of the combustion chamber. Aflue pipe 1Sforthe combustion chamber 11 is mounted in the sidewall ofthe heating chamberatthe upperend.A cylindrical hopper 14 is supported above the upper end of the heating chamber 11 such that the lower wall of the hopperandthe upper end ofthe combustion chamber are spaced apart. The hopper may be associated with an upper extension (not shown) to increase the capacity of the hopper.

A plurality of tubes 16 (only one is shown in Figure 1) are mounted between the upper hopper 14andthe combustion chamber 11 to extend between the lower wall of the hopper and the lower face ofthe heating chamber. The tubes open at their lower end into a delivery chamber 17 which is ofsubstantially inverted conical configuration and which is mounted to the lower end of the heating chamber 11. The lower end of the delivery chamber 17 is formed with an outlet 18which may be associated with a suitable gate control to control the flow of material from the delivery chamber 17.The mounting of the tube 16to the lowerwall of the hopper 14 is effected by (see Figure 3) a flange 19formed on the outerface ofthe upper end of the tubes 16 which is engaged with the upperface ofthe lowerwall ofthe hopper 14to prevent downward movement of the tube 16 past the flange 19. A ceramic washer or seal is located between the flange 19 and the plate ofthe hopper 14 to effectively seal the opening accommodating the tube 17.

The hopper 14 is provided with a plurality oftubes 20 (only one is shown in Figure 1) which extend substantially verticallyfrom the space between the heating chamber and hopperto a position clear of the material accommoated within the hopper 14.

While the space between the heating chamber and hopper serves in cooling the upper end oftheflow passageways the tubes 20 serve in heating the contents ofthe hopper using the heat extracted from the space.

The outlet 18 is provided with a water injection means (see Figure 1) comprising a nozzle extending into the chamber 17 and connected to a source of water to provide for a metered supply ofwaterto the outlet 18 whereby the amount of water provided is sufficientto effect cooling of the carbon passing from the outlet 18, to a temperature below that at which oxidation is likely to occur, but is insufficient to retard the fluid flow ofthe carbon passing from the outlet 18.

As a result of the embodiment a heat exchanger is provided for reactivating carbon whereby the carbon can be heated in isolation from the atmosphere. The injection of a metered supply of cooling watertothe outlet of the heat exchanger not only serves in cooling the material flowing from the heat exchanger to a temperature below that at which substantial oxidation can take place but also serves in isolating the interior of the delivery chamber and heat exchangertubes from the atmosphere.

Furthermore the airspace created between the combustion chamber 11 and the hopper 14 serves in cooling the hopper 14 and whilethetubes 20servein providing convectional airflow th rough the space and tube 20to enhancethecooling ofthe hopperand its contents.

If desired the hopper may be provided with means for injecting air or any suitable gas of ambient temperature into the contents ofthe hopper towards the base thereof. The percolation of the airthrough the contents which are usually heated assists in the removal of water prior to being heated further in the heating chamber.

It should be appreciated that the scope of the present invention need not be limited to the particular scope of the embodiment described above.

Claims (13)

1. A heat exchanger for heating fluid particulate material comprising a heating chamber, heating means associated with the heating chamber, a hopper mounted above the heating chamber, a delivery chamber located belowthe heating chamber, a set of flow passageways extending through the heating chamber between the hopper and delivery chamber, said delivery chamber having an outlet at its lower portion.

2. A heat exchanger as claimed in claim 1 wherein cooling means is provided between the heating chamber and the hopper.

3. A heat exchanger as claimed in claim 2 wherein the cooling means comprises spacing the base ofthe hopperfrom the heating chamber.

4. A heat exchanger as shown at claim 3wherein a plurality of airflow flow passageways extend through the hopper between the base and the upper end thereof and which open into the space attheir lower ends.

5. A heat exchanger as claimed at any one ofthe preceeding claims wherein said flow passageways comprise tubes sealingly supported by the base of the hopper.

6. A heat exchanger as claimed at any one of the preceeding claims wherein an injection means is provided at the outlet, said injection means being connected to a source of cooling fluid for providing a metered flow of cooling fluid to the material flowing from the delivery chamber.

7. A heat exchanger as claimed at claim 6 wherein the cooling fluid is water.

8. Aheatexchangerasclaimedatclaim 6 or7 wherein the metered flow of cooling fluid is sufficient to cool the fluid particulate material to a temperature below that at which substantial oxidation occurs.

9. A heat exchanger as claimed at any one of the preceeding claims wherein the fluid particulate means comprises carbon discharged from the carbon-in-pulp processing of mineral ores.

10. A heat exchanger as claimed at any one ofthe preceeding claims wherein means are provided for injecting a gaseous fluid into the contents of the hopper.

11. A heat exchanger as claimed at claim 10 wherein the gaseousfluid is air.

12. Aheat exchanger as claimed at claim 10 or 11 wherein the gaseous fluid is at ambienttemperature.

13. A heat exchanger substantially as herein described with reference to the accompanying drawings.