DE2904321A1 - Pressurised screw feeder for fine grained bulk material - where feeder drives material into pneumatic conveyor duct via swivel shutter used as non-return valve - Google Patents

Abstract

Material is driven into the top end of a vertical pipe contg. a rotary screw feeder driving the material downwards into a pressurised chamber, which also forms a conveyor duct. On the bottom end of the pipe is a non-return valve formed by a swivel shutter. In the chamber is a compressed air nozzle used to blow air underneath the shutter irrespective of the angle of the latter; and the air conveys the material along the duct. Shutter is pref. fitted on one or two levers projecting out of the chamber and connected to a mechanical-, hydraulic-, or pneumatic- device, e.g. a work cylinder, used to adjust the angle of the shutter. A graduated scale indicates the position of the shutter. Used e.g. to inject milled solid fuel into pressurised gasification reactors.

Description

DESCRIPTION

for patent application, designation: Pressure screw conveyor for introduction of fine-grain bulk materials due to higher gas pressures Bulky goods in pressurized gas spaces are of great importance for pneumatics High performance conveyor systems. In recent times this process has become increasingly important for the introduction of ground solid fuel into pressurized gasification reactors.

For the introduction of bulk materials to be conveyed into the delivery pipe intermittent and continuously operating injection methods are common. the intermittently working methods are the well-known pressure vessel conveyors where a pressure vessel is initially filled without pressure and then sealed pressure-tight after filling, under a gas pressure, usually air pressure, and by opening the delivery line valve is blown out.

This method is suitable for very high counter pressures from the delivery line however, it has several disadvantages. The intermittent Operation reduces the pumping capacity possible according to the pipeline design, double vessel systems require a great deal of effort in terms of valve and control technology, with higher outputs and bulk goods with low bulk densities are very large vessels and volumes necessary.

For larger services and especially if no high construction costs are involved pressure screw conveyors with a horizontal screw are still used today the most powerful machines.

The best known of these is the fuller pump.

With increasing funding routes, i. H. increasing length of the delivery pipeline, the counter pressure increases sharply. The most economical promotion of the anyway very energy-consuming pneumatic conveying is with the highest possible dust load of the conveying air, which also increases the back pressure. Many recurring Conveying problems therefore require the absorption of back pressures of 1.5 to 5.0 bar or more.

This back pressure must be absorbed by the screw conveyor.

The necessary sealing against the bulk material feed space one tries to achieve through various measures, as well as from numerous Patent specifications. Once is through a compression screw at the end Tried a plug formation before the introduction. A high speed of the screw should continue to give the bulk material a high mechanical acceleration to it to be introduced into the pressure chamber against the backflowing conveying air. These measures are very unsatisfactory and only allow very limited counter pressures to be absorbed less than 2.0 bar, although the energy expenditure is already above 0.5 bar counter pressure the screw and the wear increase sharply.

In the case of the horizontally mounted pressure screws, which are mounted on one side so that a flying screw in the screw conveyor tube transports the material, one often does not have due to the unavoidable snail oscillations, especially with achievable largest possible filling a high stress in the Stonfuctlse and the worm shaft bearing.

The non-return flap then brought a significant improvement Counterweight. which achieve a better seal through the formation of a material plug leaves. However, this method also has some disadvantages that prevent it from taking Dominant operating and wear conditions counter pressures of considerably more can be recorded as 2, o bar. The cause is that it is the screw outlet The fuller pump's non-return flap is supported by the one pushed out by the screw Bulk material is pressed upwards and the introduced compressed air in a fluidic very unfavorable compressed air conveying material mixing space from conveying nozzles arranged below collides against the falling material flow, is deflected and the conveying air flow is at least to a large extent pressed directly against the screw conveyor. at Unfavorable material introduction conditions can lead to such a high air countercurrent flow in the screw conveyor lead to the fact that the inward flow is either greatly reduced will or may collapse completely.

The invention described below avoids these disadvantages, in which various improvements to a new pressure screw conveyor become one lead to considerably higher counterpressure absorption.

For the smuggling of the bulk material to be conveyed, a right is given bearing screw used. Opposite the horizontally mounted screw is with this vertical arrangement ensures a more even filling level of the screw tube reached, so that the infiltration with a higher degree of filling and significantly lower Speed is reached.

Such a screw arrangement is not new. The first suggestion was already described in 1908 in the imperial patent 211946. Similar proposals are in U.S. Patent 1925 No. 1,617,959, in French Patent from 1965 No. 1.431.597 - B 65 g and in the German patent No. 849 .520 from 1952 been. However, try all of these suggestions taking pressure using the methods previously described, in the case of the French Font with an intermittent compressed air controlled odenmembrane in a pressure vessel-like room. The absorption of higher counter pressures with an optimal Dust pollution of the compressed air is therefore not possible. The present invention optimally solves the problem of counter pressure absorption by means of a non-return valve a good fluidic> Iisching section. It is crucial that before a material guide deflected in the conveying direction, the compressed air jet of the The main feed nozzle is kept away from the bulk material flow by the non-return valve, so that at the end of the flap pushed down at an angle, the horizontal acceleration path immediately occurs starts.

In some cases it is necessary to open the non-return valve for infiltration just open a small crack. In this case, the inclination surface for the Material injection must be too small.

In such an operating state, compressed air nozzles end up of the screw tube, controlled by the angle of inclination of the flap, the inlet of the Material to be conveyed is supported in the pressure mixing chamber.

In some cases it is also necessary, in the event of pressure fluctuations, z. B. because different conveying path lengths have to be controlled via transfer tubes, to throttle the material supply and for other reasons the contact pressure of the non-return valve to change. This then takes place in accordance with the back pressure from the delivery pipeline via a pneumatic, hydraulically or mechanically controlled pressure cylinder. which engages the end of the external lever of the non-return valve.

The material feed must be with a vertically arranged pressure screw done laterally. The previously known methods of lateral feeding can be used with poorly flowing bulk materials or with unfavorable structural conditions Cause supply blockages or even supply interruptions. For those according to the invention In such cases, the new pressure screw conveyor is the side Intake through a sloping tube with an inserted tubular, fine-pored loosening surface made of gas-permeable wire, sintered metal or steel wire. Through the The incoming bulk material is connected to the compressed air through the entire wall surface a finely divided gas fluid fluidizes, so that even with a slight inclination of the Inlet pipe a safer material supply achieved in a good flowable state is what immediately causes a uniform space filling of the screw conveyor tube.

This new pressure screw conveyor is described as follows.

The screw conveyor (2) mounted vertically in a pipe (1) is at the top stored in a sturdy bearing housing (3). The drive (4) can be via V-belts by a motor mounted on the side or directly by an overlying motor take place. The worm shaft passes through the worm tube (1) a stuffing box (5). The material inlet on the side is connected to a fluidizing tube Compressed air connection (6) carried out. The end of the screw tube is on the housing of the pressure chamber (7), which is also used as the bulk material conveying air mixing chamber and acceleration distance is used. The non-return valve (8) arranged below with an outwardly going shaft has one or two levers (9), which either with Counterweights, a pressure spring or a pressure cylinder (10). The position of the lever end, which at the same time the opening space and thus the inclination of the The flap in the housing is equipped with a registering mark t11).

The feed nozzle (12) is arranged below the flap so that When the flap is fully open, the compressed air is only behind after exiting the nozzle the flap hits the flow of bulk material in the conveying direction. The compressed air nozzles (13) are connected to the compressed air supply line via a solenoid valve (14) with a small amount of conveying air is only supplied when the position of the non-return valve on the registration (11) indicates a certain angle of inclination. Will this limit position exceeded, d. H. If the inclination of the flap increases, this compressed air supply is automatically activated switched off.

The back pressure manometer (15) registers the back pressure and can through an electro-pneumatic control applies the pressure to the non-return valve via a Control the pressure cylinder set at (10) in such a way that with increasing back pressure the contact pressure of the flap is increased.

in the event of an increase in back pressure in the danger zone of a pipe disruption the flap pressure is increased so that the bulk material supply is reduced so that the risk of clogging in the delivery line is eliminated.

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Claims (5)

Patent address: 1. Pressure screw conveyor for feeding in fine-grained Bulk goods against higher gas pressures, characterized in that the to be introduced Bulk material with a vertically mounted pressure screw (2) over a non-return valve (8) is pressed into a pressure chamber (7) in which the horizontally arranged compressed air delivery nozzle (12) in every position of the non-return valve, the conveying air below the valve passes through and only behind the flap in the conveying direction to the bulk material to be conveyed blows. 2. Pressure screw conveyor according to claim 1, characterized in that that the non-return flap (8) on the shaft outside with a lever (9) - for larger ones Aggregates with two levers on both sides - provided with a registering one at the end Display (11) of the lever position and a mechanical, hydraulic or pneumatic Contact pressure load (10) is equipped. 3. Pressure screw conveyor according to claim 1, characterized in that that at the end of the screw housing (1) immediately above the non-return valve (8) Conveying nozzles (13) are arranged through which compressed air via a solenoid valve (14) controlled by the position of the non-return valve (8) is introduced. 4. Pressure screw conveyor according to claim 1, characterized in that that the contact pressure of the non-return valve (8) mechanically, hydraulically or pneumatically according to the level of the back pressure registered via a corresponding pressure measuring device (15) is set. 5. Druckachneckenförderer according to claim 1, characterized in that that the bulk material feed takes place laterally via a pipe or a channel (6), in A tubular or channel-shaped, fine-pored fluidizing surface with cover connections the feed material is fluidized in such a way that a material feed also occurs when the pipe is inclined of less than 45 degrees.