Material or article handling – Static receptacle and means for charging or discharging – or... – With means to seal receptacle in vicinity of entrance for...
Reexamination Certificate
2001-12-26
2004-10-12
Dillon, Jr., Joe (Department: 3651)
Material or article handling
Static receptacle and means for charging or discharging, or...
With means to seal receptacle in vicinity of entrance for...
C222S442000, C406S132000
Reexamination Certificate
active
06802685
ABSTRACT:
The invention concerns a device and a method of transferring bulk material from a reservoir or a holding space through a lock space into a pneumatic conveyor line, wherein the lock space is closable in relation to the reservoir or holding space by a movable closure body and at least one counterpart sealing element in opposite relationship thereto in its path of movement.
Devices of that kind are to be found in EP 0 166 959 B1; at its intake side it has a conical closure body, in the center of which a vent opening surrounded by a resilient collar is cyclically closed and opened by a stepped cone of elastic material. The seal which is disposed in opposite relationship to the closure body is to be deformed by the conveyor air which is supplied thereto—through an annular passage disposed therebeneath—in such a way that the conveyor air issues uniformly directed on to the closure body and thus in the closure movement blows the closure body—seal contact line free of product. That is intended to ensure a pressure-tight sealing action for the inner lock space towards the supply reservoir. Release of the compressed air at the end of the conveyor cycle is effected directly by the now open central opening in the closure cone into the supply reservoir which is disposed thereabove and which is filled with the product to be transported. The air has to flow through the pores of the product.
It has been found that the distribution of air through the deformable seal is not so uniform that the closure body always closes against the sealing edge of the seal in pressure-tight relationship. In addition with strain gauge measurements made on the walls of the reservoir it was established that the discharge air which flows through the pores in the product, when the reservoirs are of considerable height—for example in silos—builds up pressures which make it necessary for those containers to be of a relatively great wall thickness, which thus involves higher cost levels.
That deficiency was overcome by the invention described in EP 0 270 012 B1, insofar as the air released from the lock space is passed through a tube portion at the closure cone with an opening arranged above the flow path of the bulk material, into an intake housing, and is discharged through a central opening in the intake housing. When the pressure in the lock space has fallen, the closure cone moves downwardly and the opening in the tube portion is closed in that position of the closure cone by a resilient cone tip. The opening is only open in the air release procedure; both in the conveyor mode of the apparatus and also when the bulk material is passing into the lock space, the opening is closed by the resilient cone tip. Therefore the air which is displaced by the bulk material as it flows into the lock space must be passed in counter-flow relationship through the inwardly flowing bulk material. That increases the length of the period of time required to fill the lock space.
A not inconsiderable duration for the filling operation is also involved in the arrangement of EP 0 166 951 B1. In that case, provided beneath the closure element for the outlet of the lock space is a feed line for conveyor air. The major part of the conveyor air enters here, at relatively high flow speed, due to the small cross-section involved. There is a pressure drop in the discharge housing, due to the flow being accelerated in the cross-section of the mouth opening. In a condition of co-operation with the product-air mixture which subsequently flows out of the lock space and which is discharged through the conveyor conduit, that produces an upward and downward movement of the discharge flap. As a result, the switch actuated by the discharge flap initiates vent operations before the lock container is completely emptied. Wear occurs in the discharge air lines and there is a loss in conveyor capacity due to the fact that the bulk material does not entirely discharge from the lock space. If the air feed is arranged about 3 meters downstream on the conveyor line, the described effect is eliminated, as can be seen from EP 0 270 012 B1. As in that case however the transport of product from the discharge housing to that air feed-in location only has to be overcome by the amount of air added at the closure head at the intake end, the conveyor capacity is reduced.
The conveyor capacity to be achieved depends on the duration of the cycle time. The cycle time is primarily composed of the emptying time and the filling time of the lock space. The emptying time is substantially dependent on the properties of the bulk material, the conveyor path, the conveyor cross-section, the conveyor air speed and the conveyor pressure. The filling time of the lock space is in turn substantially determined by the properties of the bulk material, the feed flow cross-section, the open cross-section of the closure head and the flow conditions in the opened closure head when the bulk material is flowing into the lock space. It has been found that the introduction of bulk material takes place reliably and quickly only with relatively grainy and heavy bulk materials, for example quartz sand and sugar in crystal form. In the case of light bulk materials in dust form the introduction thereof is uncertain and the introduction time is very long so that these devices do not achieve adequate conveyor capacities.
The device disclosed in EP 0 270 012 B1 also provides that light materials to be conveyed are fluidised in the intake housing by the air which rises in counter-flow relationship, and substantially fill the intake housing. Upon next venting of the lock space considerable amounts of the material to be conveyed are then discharged through the central opening of the intake housing. In practice those amounts of conveyor air in those apparatuses can be fixedly set by means of adjustable throttle valves; there is no regulation of the pressure and loading conditions of the conveyor flow. As a result it is not possible to make optimum use of the energy of the conveyor air which is introduced into the system. Sealing elements of elastic material are required in the known devices for permanently pressure-tightly closing off the lock space. The admissible temperature range is greatly restricted by the properties of those materials.
With knowledge of that state of the art the inventor set himself the aim of providing a simple device and a conveyor method for same, with which the levels of conveyor capacity can be increased and even light bulk materials in dust form can be transferred into a conveyor line. The invention further seeks to provide that the conveyor operation is more economical and even hot materials being conveyed can also be fed into a conveyor line.
The teaching of the independent claim provides for attainment of that object; the appendant claims set forth advantageous developments. The scope of the invention also embraces all combinations of at least two of the features disclosed in the description, the drawing and/or the claims.
In accordance with the invention the closure body has at least one vent opening which opens into an air discharge passage and is closable upon the upward closing movement of a stroke element with a sealing body; the downward opening movement thereof is also shorter than the downward movement of the stroke element with the sealing body. In that respect it has proven to be desirable for the closure body to be so designed that it enlarges from a narrow cross-section forming an inner sealing edge in a funnel-like configuration towards the sealing body and the narrow cross-section is an annular seat for the sealing body in the closure position.
In accordance with further features of the invention an air discharge passage is taken from the vent opening of the closure body to an aperture in an intake housing which is arranged upstream of the lock space, and the air discharge passage is connected to an air discharge line at the aperture in the operative condition. In addition the sealing body should be provided with a conical tip for the annular seat.
The closure bo
Bachman & LaPointe P.C.
Dillon, Jr. Joe
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