EP0691927B1

EP0691927B1 - Flowable material discharge system

Info

Publication number: EP0691927B1
Application number: EP94913553A
Authority: EP
Inventors: Paulus Egidius Raas
Original assignee: Shell Internationale Research Maatschappij BV
Current assignee: Shell Internationale Research Maatschappij BV
Priority date: 1993-04-07
Filing date: 1994-04-06
Publication date: 1996-10-30
Anticipated expiration: 2014-04-06
Also published as: EP0691927A1; KR960701790A; DE69400823D1; CN1120830A; JPH08508227A; DE69400823T2; AU6566294A; WO1994022746A1; CA2160004A1; BR9406207A; AU674229B2; ES2094057T3

Abstract

A (liftable, vibratable) outlet member (2) in the outlet of a hopper, bunker, reactor or impregnation vessel and the like. In the closed position the said member rests with its lower edge onto a seat (4). The seat (4) can be moved in downward direction making a discharge gap between it and the outlet member (2) without lifting the member and the flowable material resting on the said member.

Description

The invention relates to a flowable material discharge system for controlling the discharge of flowable material such as pellets, viscous materials such as slurries, solids, powder or particles and the like from a store such as a bunker, hopper, reactor, impregnation vessel and the like. Material such as powder or particulate material and the like is often housed in bulk in a store such as a bunker and the like, from which it is to be discharged periodically.
Known bunkers or hoppers for discharging free flowing materials such as particulate or powdered materials are provided with vertically liftable cones at their outlet.
Such liftable cones open by vertically lifting the cone against the pressure of the flowable material to be discharged on the cone.
However, such known arrangements have several disadvantages.
For example, opening is not always possible in case of large vessels or completely filled vessels.
Further, such arrangements are suitable for discharging free flowing materials, but are subject to serious problems with respect to discharging cohesive or sintering materials due to bridging, sintering and clogging of the particles. In that case lifting and vibration of the cone can cause further densification and sintering of the solids and so making flow activation even worse.
It is therefore an object of the invention to provide a simple bunker discharge system, particularly suitable for discharging cohesive, sintering, bridging or free flowing solid materials with all kinds of particle sizes.
It is another object of the invention to provide a simple bunker discharge system which is suitable for discharge in case of large vessels or completely filled vessels.
The invention therefore provides a flowable material discharge system for a bunker which is provided at its outlet with an outlet member and a seat located underneath the said member, characterized in that the said seat is movable from a first (closed) position wherein no discharge gap between the seat and the said member exists, to a second (open) position thus making a discharge gap between the seat and the said member without lifting the member, and vice versa; and further comprising means for moving the said seat in the desired direction.
Advantageously, the outlet member is (vertically) liftable and has e.g. a conical or pyramidal shape.
The invention will now be described in more detail by way of example by reference to the accompanying drawings, in which:

fig. 1 represents schematically a longitudinal section of an advantageous embodiment of the invention; and
fig. 2 represents schematically a longitudinal section of another advantageous embodiment of the invention;
fig. 3a represents schematically a longitudinal section of still another advantageous embodiment of the invention; and
fig. 3b represents a top view of the embodiment of fig. 3a.

The term "bunker" should not be understood in a restrictive manner, but also indicates e.g. hoppers, silos, containers, bins or solids process vessels like reactors, impregnation or washing vessels and the like.
Such bunkers etc. can e.g. have a conical, cylindrical, pyramidal, prismatic or spherical shape.
Referring to fig. 1 a flowable material discharge system with a(n) (inverted) cone type seat has been represented. The lower part of a bunker wall 1 with a cone type seat is represented. In the bottom of the bunker an outlet member e.g. in the form of a cone or pyramidal shaped body is provided in any suitable manner. In fig. 1 a liftable cone 2 is applied as outlet member.
The cone 2 can be moved up and down from a first (lower) position 2a to a second (lifted) position 2b and vice versa by any suitable cone actuating means 3 e.g. a pneumatic cylinder with a double piston rod and can be vibrated at any suitable frequency by any suitable cone vibrator 5. The bunker 1 is provided with a movable seat 4 located underneath the cone. The seat can be moved up and down by any suitable seat actuating means 6 from a first (upper) position (4a) to a second (lower) position (4b) and vice versa.
The shape of the bottom edge of the cone 2 needs to be such, that in its lower position (2a) it matches the shape of the seat 4 in upper position (4a) in such a way that no gap exists. Thus, in the lower position (2a) of the cone and the upper position (4a) of the seat the cone is pressed with its lower edge on the seat. In this situation there is no gap between seat and cone. Reference numeral 7 represents a support frame for supporting the cone actuating means and reference numeral 8 represents the discharge cone of the bunker.
The seat may be of any suitable shape, e.g. pyramidal, conical, spherical, flat or tore shape. The seat may consist of a single part as well as of more than one individual or collective moving parts e.g. moving flaps as will be described in connection with figs. 3a, 3b below in more detail.
In practice, there is a mechanism to prevent rotation of the liftable cone 2 and movable seat 4 (not shown for reasons of clarity).
Control mechanisms to position the cone 2 at positions between upper (2b) and lower (2a) position are useful (not shown for reasons of clarity).
Control mechanisms to position the seat 4 at positions between upper (4a) and lower (4b) position are useful (not shown for reasons of clarity).
Further, there can be a suitable mechanism to lock the seat 4 in its closed position to prevent opening due to gravity when the energy for lifting the seat might be broken down (not shown for reasons of clarity).
Further, a level sensor e.g. a capacitive level sensor underneath the seat to prevent overfilling of the space underneath the seat is useful (not shown for reasons of clarity).
In fig. 2 a flowable material discharge system with a tore seat 4', having a first (upper) position (4'a) and a second (lower) position (4'b), has been shown. The same reference numbers as in fig. 1 have been used for representing the same members of the system.
In fig. 3a a flowable material discharge system with a flap type seat 4'' is shown, wherein also the same reference numerals as in figs. 1 and 2 are used for representing the same members of the system. In this advantageous embodiment the seat is multi-sided and in particular 4-sided and comprises collective moving parts.
Further, the seat flaps 4'' are connected in any suitable manner to a hinge line 9. A bar mechanism with over centering provided with a drive shaft 10 has been shown and the said mechanism and flap are represented in open and closed position respectively (4''b, 4''a). It will be appreciated that any suitable mechanism for moving the seat flaps can be applied
In fig. 3b a top view of the flap type seat of fig. 3a is shown.
Hinge lines 9 and drive shafts 10 have been shown.
Reference numeral 6a represents a seat flaps actuating means and reference numeral 11 represents any suitable coupling mechanism such as e.g. (angular) gear boxes coupling the drive shafts 10.
Each of the sides hangs on a hinge line and is moved by bar mechanisms with over centering locking.
Advantageously, there is one common drive with a pneumatic actuator. More advantageously, the opening of the seat is adjusted with an adjustable stop in the actuator.
The operation of the system of the invention is as follows:
Upon request of flowable material the movable seat will be opened and solids can flow downwards via the gap between the outlet member and lowered seat. When required, the outlet member can be vibrated to activate and smoothen the flow. When due to bridging or sintering no flow takes place, the outlet member can be lifted and/or be vibrated to break the bridge. Vibration can be carried out at high frequencies or at a low frequency by repeatedly up and down movement of the outlet member. A very constant material flow during discharge can be achieved by vibration at high frequencies.
The flow will then be very much independent on the particle size and the internal friction. Material flow at very low throughput can be achieved by intermittently vibration of the outlet member. By selecting short successive pause vibration periods, a rather continuous flow can be achieved. During vibration periods relatively high flows outside the unstable flow - no flow region can be adjusted. In this way lifting forces do not need to be very high and flow of de-agglomerated solids is always possible.
As soon as the flowable material is activated the outlet member may be lowered again and normal discharge can take place.
When the level sensor underneath the seat is activated the seat may be closed or lifted in order to stop or reduce the flow to prevent overfilling below the seat.
Various modifications of the present invention will become apparent to those skilled in the art from the foregoing description. Such modifications are intended to fall within the scope of the appended claims.

Claims

A flowable material discharge system for a bunker which is provided at its discharge opening (8) with a separate outlet member (2) and a seat (4, 4', 4'') located underneath the said member (2), said outlet member (2) and seat (4, 4', 4'') being mounted internally of the said discharge opening (8), characterized in that the said seat (4, 4', 4'') is movable from a first closed position (4a, 4'a, 4''a) wherein no discharge gap between the seat (4, 4', 4'') and the said member (2) exists, to a second open position (4b, 4'b, 4''b) thus making a discharge gap between the seat (4, 4', 4'') and the said member (2) without lifting the member (2), and vice versa; and further comprising means (6, 6a) for moving the said seat (4, 4', 4'') in the desired direction.
The system as claimed in claim 1, characterized by means (5) for vibrating the outlet member (2).
The system as claimed in claim 1 or 2, characterized in that the outlet member (2) is vertically liftable.
The system as claimed in any one of claims 1-3, characterized in that the seat (4, 4') consists of a single movable part.
The system as claimed in any one of claims 1-3, characterized in that the seat (4'') consists of more than one movable part.
The system as claimed in any one of claims 1-5, characterized in that the seat (4, 4', 4'') has a pyramidal or conical or spherical or flat or tore shape.
The system as claimed in claim 5, characterized in that the seat (4'') is multi-sided and in particular 4-sided.
The system as claimed in any one of claims 3-7, characterized by means for preventing rotation of the liftable member (2) and seat (4).
The system as claimed in any one of claims 3-8, characterized by means (3) for moving the liftable member (2) in the desired direction.
The system as claimed in claim 9, characterized by control means to position the liftable member (2) at positions between a first, upper (2b) and second, lower (2a) position.
The system as claimed in any one of claims 1-10, characterized by control means to position the seat (4, 4', 4'') at positions between the first closed (4a, 4'a, 4''a) and the second open position (4b, 4'b, 4''b).
The system as claimed in any one of claims 1-11, characterized by means for locking the seat (4, 4', 4'') in its closed position.
The system as claimed in any one of claims 1-12, characterized by a level sensor underneath the seat (4, 4', 4'').
The system as claimed in claim 5 or 7, characterized in that each of the movable parts (4'') hangs on a hinge line (9).
The system as claimed in claim 14, characterized in that each of the movable parts (4'') is moved by a bar mechanism with over centering locking.
The system as claimed in claim 15, characterized in that the bars are driven by drive shafts (10).
The system as claimed in claim 16, characterized in that the drive shafts (10) are coupled with each other via gear boxes (11).
The system as claimed in any one of claims 14-17, characterized by one common drive with a pneumatic actuator.
The system as claimed in claim 18, characterized in that the opening of the seat (4, 4', 4'') is adjusted with an adjustable stop in the actuator (6).
The system as claimed in any one of claims 1-19, characterized in that the outlet member (2) has a conical or pyramidal shape.