EP0031559B1 - Apparatus for heating sand, gravel or similar granular materials - Google Patents

Abstract

1. Apparatus for heating sand, gravel or similar granular material, comprising arcuately profiled channels (22) arranged in a receptacle (1) containing the material to be heated for feeding a heating gas into the material, and further arcuately profiled channels (22) for discharging the heating gas from the material, characterized in that the arcuately profiled channels (22) which serve to feed the gas into the material as well as the arcuately profiled channels (22) which serve to evacuate the gas from the material are grouped in alternately laterally adjacent batteries (2, 3) each comprising several vertically superposed arcuately profiled channels and forming vertical partition walls between which the material to be heated is arranged in relatively thin layers (5).

Description

This invention relates to a device for heating sand, gravel or similar granular material, which comprises arched profile channels arranged in a silo for the material to be heated, for introducing the heating gas into the material and for discharging it therefrom.

A device for heating concrete aggregates is already known, in which a warm air blower is connected to the lower part of the silo and in the silo vault channels, which have the shape of an inverted V in cross section, are arranged one above the other, via which the air is introduced into the silo, and either run crosswise or parallel to each other, in the former case lying directly on top of each other (DE-A-2 355 253), while in the latter case short spacers are arranged between them. The parallel vaulted troughs are arranged so that their ends in the middle of the silo form a zigzag line, while with the crossed vaulted troughs every second ends near an intersection.

The disadvantage of these devices is that the curved profile channels make it difficult for the filling material to flow and do not ensure a sufficiently effective, uniform distribution of the heating gas over the filling material.

Grain dryers are also known in which the vaulted profile channels with a V cross-section are arranged in such a manner that they overlap in such a way that every second channel is connected to the supply air duct and every second channel is connected to the exhaust air duct (DE-A-1 948 099). As a result of the mutual overhang of the channels, vigorous mixing takes place in the dryer, so that the grain consumes heat of vaporization during drying and there is a lot of dust formation. This is a disadvantage if the material to be dried is sand or gravel and the task is to heat it up.

The present invention is therefore based on the object to provide a device for heating sand, gravel or similar granular material device of the aforementioned type, in which the heating extends only to a precisely limited spatial area, even if it is in a storage or Intermediate silo takes place, the volume of which considerably exceeds the required heating space, so that the heating takes place so intensively that it may be in a continuous process, ie can be done continuously.

The device according to the invention is characterized in that both the vaulted profile channels serving for supplying the heating gas and the vaulted profile channels serving for discharging the heating gas are combined to form alternately arranged batteries which comprise several vaulted profile channels located one above the other and form vertical partition walls, between which there are relatively thin layers of the to warming goods.

As a result of these relatively thin layers of material, the heating can take place by blowing heating gas, for example hot air or flue gas, through the layers within such a period of time that the desired average temperature of the layer is reached before the temperature of the layer on the heating gas discharge side is significantly higher their initial value has risen. This has the advantage that, on the one hand, the moisture contained in the material to be heated, for example the moisture contained in concrete aggregates, cannot cause energy losses in the form of heat of vaporization with the exhaust gas, since the moisture evaporating on the inlet side condenses in the cold layers of the outlet side, and that on the other hand, the dust released on the blow-in side, entrained by the heating gas, is bound again in the moist layers on the blow-out side, so that despite the high flow rate of the heating gas, no dust separation devices are required.

In the device according to the invention, the flow of the material to be heated is designed such that no mixing takes place, and the flow of the heating gas is such that the end face is very large over the entire flow length and the flow path is short. Because of this and because of the small heating zone volume, the device works at high speed, and the need for thermal insulation between the environment and the heating system is completely insignificant, not least because the heating zone is more or less completely in the middle of the material to be heated, depending on the size of the silo.

According to an advantageous embodiment of the device according to the invention, the one end of each vaulted profile gutter battery used for introducing heating gas is connected to a heating gas distribution chamber, which in turn is connected to the heating gas supply line. Also in the case of the vault profile channel batteries used to discharge the heating gas, one end is either connected to a collecting chamber, which in turn opens into the discharge duct, or the individual vault profile channel battery is connected to its own fume cupboard, which in turn is in its own, with the Throttle valve provided for regulating the heating gas flow opens the discharge shaft.

According to an advantageous embodiment of the device according to the invention, the vault profile channel batteries are arranged loosely on stationary guide pairs, which lead from the distribution chamber to the vault profile channel batteries used for introducing heating gas and from the vault profile channel batteries serving to discharge the heating gas to the collection chamber or to have openings leading to the discharge channels.

The arch profile channel batteries are preferably formed by two or more arch profile cassettes located one above the other, which in turn consist of several arch profile channels located one above the other. In this way, these parts exposed to wear and tear cannot be replaced. All you have to do is lift out the worn cassette and insert a new one.

To balance the heating gas flow and of the flow of the material to be heated, each of the vault profile trough batteries used for introducing heating gas can be provided with its own throttle valve for regulating the gas flow, or between the vault profile channel batteries, limiting plates can be used to reduce the heating gas flow in the areas of the material layers in which the flow of the material to be heated is restricted or prevented, are used and / or obstacles which slow down the flow of material can be arranged between the arch profile channel batteries and serve to compensate for the flow rate of the material to be heated in the individual material layers.

The invention will be described in more detail below with reference to the exemplary embodiment of the device according to the invention shown in the accompanying drawings.

• Fig. 1 einen Zuschlagstoff-Silo mit eingebauter erfindungsgemässer Aufheizvorrichtung im Vertikalschnitt;
• Fig. 2 den gleichen Silo im Vertikalschnitt, der rechtwinklig zum Schnitt von Fig. 1 geführt ist;
• Fig. 3 die Vorrichtung nach Fig. 1 und 2 im Horizontalschnitt längs der in Fig. 1 angedeuteten Geraden 111-111;
• Fig. 4 eine einzelne Wölbprofilkassette seitlich betrachtet;
• Fig. 5 die gleiche Kassette stirnseitig betrachtet, wobei in letzterer Figur punktgestrichelt die zur gleichen Wölbprofilrinnen-Batterie gehörende obere und untere Kassette dargestellt sind;
• Fig. 6 einen Teil der Aufheizgas-Verteilerkammer mit Montageführungen und Einblasöffnungen für die Wölbprofilrinnen-Batterien;
• Fig. 7 einen Schnitt längs der in Fig. 6 angedeuteten Geraden VII-VII;
• Fig. 8 und 9 eine modifizierte Ausführungsform der erfindungsgemässen Vorrichtung in entsprechender Darstellung wie in Fig. 1 und 2.

Show it:

• Figure 1 shows an aggregate silo with built-in heating device according to the invention in vertical section.
• Figure 2 shows the same silo in vertical section, which is guided at right angles to the section of Figure 1;
• 3 shows the device according to FIGS. 1 and 2 in horizontal section along the straight line 111-111 indicated in FIG. 1;
• 4 shows a single arch profile cassette viewed from the side;
• 5 shows the same cassette on the end face, the upper and lower cassette belonging to the same arch profile channel battery being shown in broken lines in the latter figure;
• 6 shows a part of the heating gas distribution chamber with mounting guides and injection openings for the arch profile channel batteries;
• 7 shows a section along the line VII-VII indicated in FIG. 6;
• 8 and 9 a modified embodiment of the device according to the invention in a corresponding representation as in FIGS. 1 and 2.

The heating device according to the invention shown in FIGS. 1 to 3 comprises a plurality of batteries 2, 3 of arched channels arranged in the aggregate silo 1 or in a corresponding container, which are inserted at short intervals parallel to one another between guide pairs 4, by means of which they are supported at both ends . Vertical layers 5 of the aggregate to be heated are formed between the arch profile channel batteries 2, 3, which can flow freely downward inside the cone 15 (FIG. 8) to the removal hatch 6 of the silo. The guides 4 are fastened on one side of the arch profile channel batteries 2, 3 to a heating medium distribution chamber 7 which has an inlet opening 8 in every second arch profile channel battery 2. A supply pipe 14 connected to the heating gas source is connected to the distribution chamber 7, via which the heating gas is passed to the distribution chamber 7 and from there via the arch profile channel batteries 2 into the additive to be heated. On the opposite side, the guides 4 are fastened to the discharge channels 11, each of which has a discharge opening 10 in the case of the arch profile channel batteries 3 which are not connected to the distribution chamber 7 via inlet openings 8.

The heating gas, for example hot air or a flue gas-air mixture, is introduced into the additive layers 5 via the pipe 14 and the distribution chamber 7 and also via the vault profile channel batteries 2 connected to it. The heating gas flows through the aggregate layers 5 into the vault profile channel batteries 3 connected to the extraction channels 11 and via these into the extraction channels 11. In the exemplary embodiment shown, the extraction channels are each connected to their own extraction duct 12, and each of these extraction ducts 12 is equipped with one Flow control valve 13 provided. With these control flaps 13, when using a continuously operating heating device, the heating gas flow through the individual material layers 5 can be regulated in such a way that it corresponds to the average flow rate of the aggregate in the individual aggregate layers 5. If, on the other hand, the aggregate is heated in batches and especially in a special container that is smaller than the actual silo and corresponds to the volume of the aggregate batch to be heated, the control flaps 13 are unnecessary, since the aggregate is then in the rooms 5 all the time remains between the arch profile channel batteries 2, 3.

4 and 5 show the curved profile cassettes used in the heating device according to the invention on a larger scale. Such a cassette consists of arched troughs 22 which are arranged at suitable intervals and are attached to vertical brackets 21 and which have the shape of an upside down V in cross section. The arch profile channels can be fastened to the brackets 21, for example by welding. In the embodiment shown in FIGS. 4 and 5, the individual cassette comprises four arch profile channels 22 arranged one above the other, and in the embodiment shown in FIGS. 1 and 2, the individual battery profile channel battery 2, 3 comprises three arch profile cassettes arranged one above the other.

7 and 8, the heating gas distribution chamber 7 is shown, which is supported on the silo structure 1 in a suitable manner, not shown. U-shaped guides 4 for the arch profile channel batteries 2, 3 are fastened to the distributor chamber 7. At every second guide 4 there is the opening 8, through which the heating gas can flow under the arched channels 22 of the battery channel 2. On the trigger channels 11, which are also supported on the silo structure, the guides 4 for the arch profile channel batteries 2, 3 are fastened at corresponding locations, and in the trigger channel wall there is an opening 10 in a corresponding manner with every second guide 4, but with the openings 10 are offset from the injection duct openings 8.

The heating gas is passed via the pipe 14 into the distribution chamber 7, from where it flows through the openings 8 under the arched channels of the curved channel batteries 2. As can be seen from FIG. 5, the cavities form under the arched profile channels 9, in which the heating medium flows almost unhindered over the entire length of the arch profile channels and thus spread over the aggregate layer 5 with a large end face and likewise flow through this with a large end face and reach the arch profile channel batteries 3 and continue through their cavities 9 the openings 10 can flow into the discharge channels 11.

The heating device according to the invention can be used either as a continuous or as a batch device. In continuous operation, the heater is placed inside the silo near the floor. With each removal, the amount of heat required to heat the amount of material to be removed from the silo in batches is blown into the heating device each time it is removed. In the case of batch operation, on the other hand, the net capacity of the heating container corresponds to the maximum batch.

When working with a continuous heating device, there is the disadvantage that the material to be heated is in the spaces between the arch profile channel batteries 2, 3, i.e. in the layers 5 may flow unevenly, with the result that the material may overheat at points of low flow velocity, which in turn means that the outlet temperature of the heating gas rises and the efficiency of the heating decreases.

Such an uneven flow of the goods can be prevented, for example, by applying motor vibrators 19 which are wear-resistant and encapsulated to the uppermost arch profile cassettes of the edge-side arch channel batteries, which promote the uniform flow of the material to be heated. As an alternative or in addition to the aforementioned measure, bars 17 can be arranged in the manner shown in FIG. 9 on the uppermost cassettes or below the lowermost cassettes in the areas of the fastest flow, which can be easily moved to the correct position experimentally. The rails 17 are preferably arranged freely on pins 18 located on the uppermost arch profile cassettes in relatively close succession.

Furthermore, the heating gas flow can be limited in the manner shown in FIGS. 8 and 9 by limiting plates 16, the task of which is, depending on whether the point in question is a passive supply of the material to be heated that remains completely in place or only below average weak material flow is, the flow of heating gas through the layer 5 either over the entire length, ie to prevent the entire height of the arch profile channel batteries 2, 3 or only over part of this length. 1 to 3 as well as 8 and 9, the reference numeral 20 denotes the passive supply remaining between the silo wall and the heating device according to the invention, which remains at the point and which acts as a thermal insulation layer between the heating device and the surroundings.

With regard to the intensity of the heat transfer, it is advantageous if the heating device according to the invention is operated with sufficiently hot heating gas. For example, in the concrete station of a precast plant, when heating up cold concrete aggregates to a temperature of 70 to 90 ° C, the heating gas can have a temperature of 200 to 500 ° C, whereby the heating up time and thus the start-up time of the cold heating system is only a few minutes.

The heating gas can be circulated in the heating device according to the invention either in the form of a closed or an open system. In the closed system, the gases from the discharge shaft 12 are again fed to the heat source and then fed into the pipe 14. If the flue gases of the heat source are mixed with the heating gas, only a quantity of gas corresponding to the quantity of flue gas has to be removed from the closed circuit. In the case of the open system, the heating gases in their entirety are conducted out of the exhaust duct.

Claims (10)

1. Apparatus for heating sand, gravel or similar granular material, comprising arcuately profiled channels (22) arranged in a receptacle (1) containing the material to be heatet for feeding a heating gas into the material, and further arcuately profiled channels (22) for discharging the heating gas from the material, characterised in that the arcuately profiled channels (22) which serve to feed the gas into the material as well as the arcuately profiled channels (22) which serve to evacuate the gas from the material are grouped in alternately laterally adjacent batteries (2, 3) each comprising several vertically superposed arcuately profiled channels and forming vertical partition walls between which the material to be heated is arranged in relatively thin lavers (5).

2. Apparatus according to Claim 1, characterised in that one end of each arcuately profiled channel battery (2) serving to feed the heating gas is in communication with the heating-gas distributor chamber (7) which latter is connected to the heating-gas supply pipe system (14).

3. Apparatus according to Claim 1 or 2, characterised in that one end of each of the arcuately profiled channel batteries (3) serving the discharge of heating gas is in communication with a collector chamber which latter is connected to a draft flue.

4. Apparatus according to Claim 1 or 2, characterised in that one end of each of the arcuately profiled channel-batteries (3) serving for heating-gas discharge is in communication with its individually associated discharge channel (11) which latter is in its turn connected to an individually associated draft flue (12) provided with a butterfly-valve (13) for the regulation of the heating-gas-flow.

5. Apparatus according to any of the preceding claims, characterised in that the arcuately-profiled channel-batteries (2, 3) are loosely arranged on fixed pairs of guides (4) which are provided with orifices (8) leading from the distributor chamber (7) to the gas-feed-batteries (2) of arcuately profiled channels and further orifices (10) leading from the gas-discharge batteries (3) of arcuately profiled channels to the collector chamber orto the discharge channels (11).

6. Apparatus according to claim 5, characterised in that each individual battery (2, 3) of arcuately profiled channels consists of two or more vertically stacked arcuately profiled cassettes, each individual cassette being formed by several vertically stacked arcuately profiled channels (22).

7. Apparatus according to any of claims 2 to 6, characterised in that each of the batteries (2) of arcuately profiled channels serving to feed the gas into the material is provided with an individually associated butterfly valve for regulating the flow of heating gas.

8. Apparatus according to any preceding claim, characterised by the provision, between the batteries (2, 3) of arcuately profiled channels, of gas- baffle sheets (16) for reducing gas flow in the regions of the layers of material (5) in which only a limited or nil flow of material occurs.

9. Apparatus according to any preceding claim, characterised by the provision of obstacles (17) arranged between the batteries (2, 3) of arcuately profiled channels which are designed to brake the flow of the material in the individual layers (5).

10. Apparatus according to any preceding claim, characterised in that, with the exception of the heating-gas supply pipe (14) and the gas-discharge flue or flues (12) it is arranged in its totality inside the receptacle (1) containing the material to be heated in such a manner that a stagnant layer (20) of material functioning as a thermal insulation layer remains between the outer circumferential wall of the container (1) and the heating apparatus.

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