HU195676B - Fluidizing apparatus first of all for heat treating metal pieces - Google Patents

Abstract

The present invention relates to a fluidized bed apparatus, in particular for the heat treatment of metal parts, comprising a melting shell (1) of a heat-resistant particle forming a fluid bed, a grate (3) having a fluid-gas inlet opening (1) from the bottom (1), and an electric heating element (7) provided with a protective cover (9), preferably provided with a protective device arranged in the interior of the jacket (1). According to the invention, there are fluid-resistant heat-resistant particles inside the protective device of the electric heater (7), preferably within its protective cover (9), and there are inlets (12,13) for introducing and removing the fluidizing gas, preferably the protective cap (9). -1-

Description

BACKGROUND OF THE INVENTION The present invention relates to fluid bed apparatus, in particular to heat treatment of metal parts.

Fluidized bed units having a casing made of a heat-resistant material that receives the fluidized bed granules, a grid with fluidized gas inlets to seal the casing from below, and electric REYNEDs with a protective casing, such as RW, are provided in the jacket. Fisidised Bcds for Heat Trcatment of Metals, Heat Treatment of Metals, 1976. 4, pp. 92-100). The disadvantage of these devices is that the casing (which protects the radiators against mechanical influences by mechanical tubes) reduces the heat transfer and greatly increases the heating time.

The cited publication also mentions the use of so-called mineral-insulated metal jacketed heating elements, adding that even fluidization is extremely important in these cases, since overheating in stagnant areas can lead to equipment failure. Thus, this solution can be used only to a limited extent and only at lower temperatures (up to about 500 ° C). a very significant disadvantage of this is the long rise time.

It is an object of the present invention to overcome these drawbacks. It is therefore an object of the present invention to provide a fluidized bed apparatus having good heat transfer between electric radiators and the working space, short heating up time, local overheating and consequent damage, and increased operating temperature.

The object of the present invention is to heat a fluidized bed apparatus, in particular metal parts, having a jacket made of a heat-resistant material that receives the fluidized bed granules, a grid with fluidized gas inlets to seal the mantle from below, and an electric heater body wherein, in accordance with the present invention, there are fluidizable heat-resistant particles within the housing of the electric heater, and the housing having inlets and outlets for fluidizing gas.

In a preferred embodiment of the apparatus according to the invention, the protective housing of the electric heater is an open tube at both ends, the longitudinal axis of which is parallel to the main flow direction of the fluidizing gas introduced into the interior of the jacket.

In another preferred embodiment, the fluid heater inlet of the electric heater housing is connected to an air duct connected to a separate gas source. Preferably, the apparatus of the invention has a duct for supplying additional air to the upper portion of the jacket. It is further preferred that the grate is provided with an air-cooled heat exchanger and that the supply air supply duct is connected to the outlet of the heat exchanger.

Finally, it is advantageous to have a screen, preferably a screen, between the electric heater and the working space of the unit.

The invention will now be further described with reference to the embodiments outlined in the accompanying drawings. The

Figure 1 is a longitudinal sectional view of the apparatus of the first example, a

Figure 2 is a plan view of the apparatus of Figure 1, a

Figure 3 is a longitudinal sectional view of the apparatus of the second example, and

Figure 4 is a longitudinal section through the apparatus of the third example.

I

1-2. The apparatus according to Figs. The grate 3 is provided with openings g (preferably formed from so-called sponge ceramic) for fluidizing gas. The gas is introduced under the grate 3 through a tubular tube 4 inserted into the central bore of the base plate 2.

Between the lower edge of the jacket 1 and the base plate 2, a toroidal heat exchanger 6 is provided, the internal passage of which is connected via an air source 5 (not shown), e.g. compressor).

Inside the housing 1, electric radiators 7 are arranged vertically evenly spaced along its longitudinal axis coaxially dividing. Each heater 7 is provided with a cylindrical tubular protective device made of heat-resistant steel, preferably a protective case 9. the upper end of the lower tube forming an inlet 12 a drain outlet 13.

A coaxial, cylindrical rain shield 8 is thus arranged from the protective cases 9 to the longitudinal axis of the sheath 1. Within this, there are actually 15 working units of the equipment.

During the operation of the apparatus of Fig. 12, the heat / desired workpieces are placed on the grate 3 and the space inside the jacket 1 is filled with approximately 2/3 of 25 parts of refractory particles (e.g., corundum particles). The electric radiators 7 are then switched on and a fluidizing gas is introduced through the nozzle 4 and cooling air is introduced through the connection 5. The grain bed system (fluid bed) suspended by the upwardly fluidizing gas provides a rapid and efficient heat transfer between the radiators 7 and the workpieces 15 in the working space.

The air flowing in the heat exchanger 6, which protects the grate 3 from overheating, partially discharges its heat content into the outside space. The protective grille 8 protects the radiators 7 from mechanical impact 35 and damage.

The protective means, preferably the protective cases 9, which may be completely closed or perforated, prevent local overheating of the radiators 7. The inner space of the protective cases 9 is also filled with refractory particles 40, which are held in motion by the fluidizing gas entering through the openings 2 and leaving the openings 13.

In the apparatus of Fig. 3, the lower ends of the protective sleeves 9 are annularly connected to the jacket 1 by a coaxial duct 10 which is connected to a separate gas source 45 (not shown) via a duct 11. In this case, the fluidization in the working space 15 and the protective housing 9 can be independently regulated, while avoiding that the gas used in the working space will damage the radiators 7.

The guard grille 8 is not shown in Figure 3, but of course can be used here.

In the apparatus of Fig. 4, the radiators 7 are surrounded by a protective casing 8 formed by the sheath 1, in which refractory particles are suspended by means of a fluidizing gas introduced through the spout 4, which enters the annular opening 12 and it passes through an annular opening 13.

Another difference is that the heated air exiting the heat exchanger 6 is led via a duct 14 to the upper part 50 of the jacket 1, which enters around it to supply combustion of flammable fluidizing gases, thereby making the unit more heated, improving its efficiency and reducing environmental pollution. Auxiliary air is introduced above the upper level of the fluidized medium at about 3/4 of the height of the jacket 1 at 55.

-2195,676

The apparatus according to the invention has a significantly shorter heating time than known, better thermal efficiency, a lower risk of damage to electric heaters and a higher allowable operating temperature.

Claims (6)

1. A fluid bed apparatus, in particular for heat treatment of metal parts, having a jacket of heat-resistant material receiving the fluid bed granules, a grate having a vent opening for sealing the jacket from below, and an electric heater having a protective device arranged inside the jacket. that the protective means of the electric heater (7) preferably has fluidizable heatable particles within its protective casing (9) and that the protective means, preferably the protective casing (9), have fluid inlet and outlet openings (12,13). Apparatus according to claim 1, characterized in that the protective means, preferably the protective casing (9) of the electric heater (7) is an open tube at both ends, the longitudinal axis of which is parallel to the main flow direction of the fluidizing gas introduced into the inner space of the jacket . Apparatus according to Claim 1, characterized in that the protective element, preferably the protective casing (9) of the electric heater (7), is connected to an air duct (q) connected to a separate gas source. 4. Apparatus according to any one of claims 1 to 4, characterized in that it has a duct (14) for supplying additional air to the upper part of the jacket (1). Apparatus according to claim 4, characterized in that the grate (3) is provided with an air-cooled heat exchanger (b) and the supply air supply duct (14) is connected to the outlet of the heat exchanger (6). 6. Device according to any one of claims 1 to 3, characterized in that the protective device is formed as a protective wall between the electric heater (7) and the working space (15) of the device, preferably as a protective grid (8).