FI96297C - Apparatus for dispensing a powdered substance from a tank - Google Patents

Description

96297

Apparatus for dispensing a powdered substance from a tank

The invention relates to an apparatus for lifting an powdery substance from a container. Such powdered substances include e.g. various constituents of concretes and mortars. These substances are practically very difficult to flow and do not want to come from their tank by gravity, and if they do, their outflow is quite uneven, 10 due to e.g. the tendency of the substance to vault into the outflow section of the tank. Such an outflow portion is a generally funnel-shaped lower portion of a cylindrical storage container having a substance outlet opening at a downwardly directed tip.

In order to provide a more even and secure flow of substance from such a funnel-like part, Finnish Patent No. 80430 proposes a structure for an outflow funnel in which elements are provided in the inner walls of the funnel (or bottom cone) through which pressurized air can be introduced. These elements are preferably made of perforated metal plates welded to the wall of the funnel in such a way that a flow channel for compressed air or other medium gas 25 remains between the plates and the wall. This medium is preferably guided through a perforation in the plate which directs the flow of medium in the desired direction of movement of the substance.

The material thus obtained in the fluidized state has been found to flow substantially evenly from the funnel and without vaulting problems. The flow is regulated by a control valve located in the outflow opening, which can be, for example, a rotary valve known per se. This valve has a flap corresponding to the cross-section of the flow orifice, which is rotatable about an axis of rotation 35 corresponding to the diameter of the cross-sectional plane of the flow orifice. At high fluid flow rates, this control valve has been found to operate quite satisfactorily. Also, the rapid shut-off of the flow 2 96297 with this valve is without major problems.

Instead, problems arise when the flows are strongly 5 choked. In such an adjustment situation, the flap of the rotary valve is twisted approximately to its closed position, leaving only narrow flow crescent-shaped flow slits on the two opposite edges of the flap. In this situation, the flow opening is above all very narrow at the tips of the crescent moon. These very narrow slits have the unfavorable effect under flow conditions that the powder coarser particles do not escape freely from this flow region in the same way as from the even looser central region of the slot. Coarse materials start to accumulate and quickly clog the entire flow opening.

Accumulations may also form in the narrow gap area with some substances, which further complicates the correct implementation of flow control.

20 There has been a substantial improvement in these problems. The invention is based on the realization that a second rotary flap valve with a diameter smaller than the main flap 25, which can be adjusted independently of the main flap, is placed in the rotary flap valve which regulates the flow from the outflow opening of the apparatus. With this arrangement, it is possible to avoid the formation of the above-mentioned crevice situation with strongly constricted flows. To control the throttled flow, 30 smaller diameter valves can be used, which can be in a substantially open position with a certain throttled flow, in which case the main flap would be in a position quite close to its closed position.

The invention will be explained in more detail with the aid of the accompanying drawing, in which 3 96297

Figure 1 is a cross-sectional view of the apparatus showing a funnel-shaped outflow section located at the bottom of the material container and the flow-promoting elements located therein.

Figure 2 is a top view of the corresponding apparatus, and a

Figure 3 shows a valve according to the invention placed in the outflow opening of the apparatus in three operating positions.

Figure 1 shows a funnel-shaped or conical outflow section at the bottom of a container 17 containing a powdered substance, indicated generally by reference 1. The bottom of the funnel has an outlet 3 from which the flow is controlled by a valve, the structure of which is explained in more detail below. In order to facilitate the flow of the powdered substance and to avoid vaults, elements 4 are provided in the inner walls of the hopper 1, through which, for example, pressurized air can be introduced into the substance to be removed. The air is introduced to such an extent that the substance to be removed is brought into a sensitive, fluidized state, but on the other hand the amount of air flow is controlled by suitable flow restrictor 11 so that air currents cannot escape strongly upwards through the material to be removed.

These members 4 consist, for example, of a torn metal plate welded to the inner surface of the hopper 1 so that a suitable flow channel for pressurized air remains between them and the wall 2 of the hopper. The air is suitably led to these ducts at different heights through the put-35 outlets 14, 15. As can be seen from Figure 2, there may be four elements 4 evenly spaced around the funnel, or their number may be smaller, 96297 4 such as three. It is also possible to place more than four elements.

A control valve located in the flow port 3 is shown in Fig. 3. The valve consists of a conventional rotary valve with a circulating flap 5 closing its flow port. According to the invention, a second, smaller diameter rotary flap valve 7 is arranged centrally in the rotary flap 5. The rotation shafts 6 and 8 of the flaps can be rotated independently of each other, whereby the operating positions shown in Figure 3 as different alternatives can be provided for the valve.

20 Contrary to the structure according to Figure 3, the operating mechanisms of the flaps 5 and 7 can also be placed on opposite sides of the valve. Likewise, a smaller flap can be placed on the main flap other than centrally if it is considered appropriate for some reason.

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Claims (2)

96297 Claim: Apparatus for dispensing a powdered substance from a container, the device comprising an upside down cone-shaped lower part (1) provided in the lower part 5 of the container containing the substance (17), the substance having an outlet (3) at its tip a recirculation valve located in the outlet 10 (3), characterized in that the main flap of the recirculation valve is provided with a smaller diameter, independently opening and closing recirculation valve for introducing other medium gas into the substance to be discharged and to facilitate its discharge. 15 Patenting: Anordning for the dosage of powdered material from the use of the same material (17), in which case the material is used, up to 20 orders per day (1) with the formulation up to and including (3) for material, and for use in the manufacture of raw materials (4) for use in the manufacture of gas or medium-sized material in the form of a medium for the purpose of utilization-25 Ning, as well as for utilization (3) anordnad vridklaff- valve, kännetecknad därav, att vridklaffventilens interesud-klaff är försedd med en till sin sin diameter mindre, själv-ständingt öppnings- och stängbar vridklaffventil.