DK168319B1 - Appliance for heating food material - Google Patents

Abstract

In an apparatus for continuous heat treatment, a mechanically fluidized stream of material consisting preferably of a granular or highly viscous material is heated in a rotating chamber in co-current with heat energy originating from a burner (1), in which solid, liquid or gaseous fuel is burned. A portion of the energy liberated by the combustion heats the internal part of a thin-walled chamber (5), the external part of which at the material inlet (10) transfers energy to said stream of material in the form of radiant heat. The remaining portion of the energy liberated by the combustion, bound in the exhaust gases from the combustion process, are subjected to heat exchange in a primary convective heat exchanger (7) and one or more secondary heat exchangers (8) in counter-current with a gaseous process medium, preferably atmospheric air, said process medium transferring further energy to said stream of material in the form of convective energy.

Description

DK 168319 B1

The invention relates to an apparatus for heating food material which is of the kind specified in the preamble of claim 1.

An apparatus of this kind is known from U.S. Patent No. 1,547,655. This known apparatus thus comprises a container - in the example shown a rotating drum - wherein the material intended for heating, e.g. coffee beans are heated by means of a chamber closed with respect to the drum through which hot gas or steam is conducted. This design has the advantage that the material intended for heating does not come into contact with the hot gas or steam, so that the pollution of the material is avoided, but on the other hand the apparatus has a poor heat economy, partly because the hot gas or steam which must supply heat to the material, supplied through pipes of not insignificant length, with consequent loss of heat, partly because the "spent" gas or steam is discharged to a chimney without utilizing its residual heat content.

US Patent No. 3,343,584 discloses an apparatus intended for heating bulk material in the form of a fluidized bed of particulate material. In the apparatus thus known, the combustion gases are discharged from the chamber in which the burner is placed and which gives off heat to the space in which the masses intended for heating are located, and the combustion gases thus come into contact with the masses, which in part entails the advantage that very little of the heat is lost, partly the disadvantage of heating sensitive materials, e.g. cereals, 30 which must constitute or be included in foodstuffs, that the contents of the combustion gases, e.g. Nitrogen oxides can greatly degrade the heating material intended for heating.

Accordingly, it is the object of the invention to provide an apparatus of the kind mentioned above, in which the aforementioned disadvantages are avoided while retaining the advantages obtained, and this object is achieved by an apparatus which also exhibits the features which is characterized in the characteristic part of claim 1. First, it is achieved that the loss in heat transfer, which results from the fact that heat is not delivered to the bulk material through the combustion gases, is offset by using a special heat transfer fluid, preferably in the form of air or an inert gas, to transfer it. 10 heat which is not radiant heat from the chamber, and thus from the combustion gases, to the bulk goods, and secondly, that the heat economy on the heat supply side is improved, as heat is generated in the chamber itself and losses from long supply lines are avoided.

In the embodiment of claim 2, it is prevented that any leaks allow combustion gases to flow into the compartments or channels in which the heat transfer fluid flows.

The invention will be explained in more detail below with reference to the exemplary embodiment of an apparatus according to the invention shown in the drawing.

In a burner 1, solid, liquid or gaseous fuel is burned with an excess of air, so that the combustion zone 2 (the flame) has an average temperature in the range of 400 ° C-1200 ° C, preferably 600 ° C-1000 ° C.

The combustion takes place in a burner pipe 3, which is insulated internally with a refractory material, so that heat transmission from the interior wall of the burner pipe to the outer wall is minimized.

Thus, the energy released by the combustion will essentially be conveyed to the mouth of the burner tube and into the inner part 4 of a thin-walled chamber 5.

The chamber 5 can, as shown, be shaped like a cylinder with a bottom with a shape as a ball surface section and consist of a high-refractory material (metal or ceramic).

The chamber 5 will be heated in the range of 400 ° C to 1200 ° C / 5, preferably 600 ° C-10000C, and emit heat radiation from the outside of the chamber.

The exhaust gases, after staying in the interior space 4 of the chamber 5, will pass in a space 6 between the outside of the burner tube and the for example cylindrical part of the chamber 5, hereinafter called the primary convective heat exchanger 7.

At the above passage, the exhaust gases can ensure a turbulent flow process by means of baffles or the like, so that contact with the primary convective heat exchanger 7 is maximized.

The exhaust gases leave the primary convective heat exchanger 7 upon suction, and may be further cooled in one or more external secondary convective heat exchangers 8b and 8a, respectively.

After cooling and suction using the fan 16 20, the exhaust gases leave the system at 17.

The gaseous process medium, for example atmospheric air, is sucked in at 19 by the fan 18 and heated in one or more convective heat exchangers 8a and 8b, respectively, before the process medium passes between the refractory 25 primary convective heat exchanger 7 and a manifold 21 and enters the process chamber 11 .

In the above passage, the process medium can ensure a turbulent flow process by means of baffles or the like, so that contact with the primary convective heat exchanger 7 is maximized.

DK 168319 B1 4

The material to be treated according to the invention is fed into an inlet slit 10 in the rotating process chamber 11.

5 The material is held by means of vanes or the like according to known principles in a mechanically fluidized state and is moved from the inlet slide 10 to the ejection housing 12.

The material is subjected at the inlet end of the rotating chamber 11 to an intense heat effect, partly in the form of heat radiation emitted by the chamber 5, and partly in the form of convective energy transfer, supplied from the heated gaseous process medium.

The intensity of the heat effect of the material decreases as the material moves from the inlet end, at the inlet slide 10, towards the outlet end at the outlet housing 12.

When heating granular material, the heat transmission from the chamber 5 to the material flow decreases as the particles shade for each other and their temperature increases.

The heat transmission from the heated gaseous process medium to the material flow decreases as the process medium cools and, for example, the temperature of the particles increases.

After a given predetermined heat effect time, the material and process medium are separated according to known principles in the exhaust housing 12 and the material is discharged through the airtight lock 13.

The cooled process medium is passed through the tube 14 to the cyclone 15, where possible. dusty parts according to known principles 30 are separated, and then, possibly, together with the exhaust gases, to be further cooled in the lower secondary DK 168319 B1 heat exchanger 8a.

Possibly. condensate from the further cooling of the process medium as well as any. the exhaust gases are drained at 20.

Claims (2)

1. Apparatus for heating liquid or rubbish capable food material and of the type comprising: (a) a chamber (5), the interior of which is adapted to receive heat in the form of hot gas and whose wall or walls are arranged for transferring the heat thus received to the food material, this heat being emitted from the outside of the chamber wall or walls by radiation and conduit, and b) degassing means (6, 17) to conduct spent hot gas from the chamber (5), c) the degassing means (6, 17) are arranged to direct the spent hot gas from the chamber (5) outside the heating area or areas where the food material intended for heating is characterized, d) the apparatus comprises a burner (1, 2, 3), whose combustion products constitute the hot gas, and which is so arranged in the chamber (5) that it also emits heat by direct radiation with the inner wall of the chamber (5), and e) the apparatus comprises fluid conductors (19, 8a). , 8b, 21. to lead a fluid capable of absorbing and supplying heat by conduction, separated from the spent hot gas and in heat conductive contact, first with the outside of the chamber (5), and then with the food material intended for heating, the fluid conducting means comprising at least one heat exchanger (8a ) if one side 30 enters the passage between the inlet point (19) of the fluid and the space (2) around the outer wall of the chamber (5) and the other side enters the passage between the area (11) where the fluid delivers heat to the food material and that of the fluid. outlet location (17). 35 Apparatus according to claim 1, characterized in that the static gas pressure in the fluid (in claim 1, item DK 168319 B1 7 e) is constantly maintained higher than the static gas pressure in the combustion gases.