Apparatus for separating dust, dirt and the like from particulate material

The invention relates to a device for separating heavier grains of bulk material from lighter grains and dust by means of at least one grate arranged in a housing, which is fed by an inlet opening out above its edge with the bulk material and by an upward, circulating within the housing that flows through lighter grains and the dust-entraining airflow of such throughput, that the heavier grains fall through the rust. Devices of this type are known. They require constant supervision and occasional adjustment, u m with high efficiency to be able to separate the heavier grains.

The object of the invention is in contrast to keep the separation efficiency in such a device without constant supervision and adjustment of the device automatically at a high level.

The solution of this problem is specified in the characterizing part of claim 1.

In the apparatus according to the invention, it is possible to set a relatively strong inlet flow to the grate and thus a relatively high throughput. The heavier grains, which do not fall through the rust, and all grains in the border area get into the collecting container and then into the ascending sifter. Here is an exact separation of heavy grains and grains in the border area. The level sensor ensures that the sump is not overfilled. In order to coordinate the loading of the grate through the inlet and the feeder of the riser sifter, the device is preferably dadu characterized in that the outlet cross sections of the inlet to the grate and the sump to the riser are variable and coupled together with increasing amount of befindlichem in the inlet

so to increase bulk. With an increase in the supply of the grate is thus accompanied by an increase in the load of the riser sifter.

So that the bulk material is evenly distributed over the grate, the grate preferably runs obliquely downwards from the inlet to the collecting container.

In order to be able to adjust the proportion of the bulk material which enters the collecting container, the collecting container preferably has a height-adjustable side wall facing the inlet.

To set, control and coordination of the air flow to each other various measures can be taken. It has proven particularly useful that downstream of the grate and the climber adjustable flaps for adjusting the passage cross-section and control of the Lu ftstroms are arranged.

To the separated lighter grains and the

To be able to remove dust, the device is preferably characterized in that downstream

of the grate and the sifter one after the other a separator space for the lighter grains and a separator for the dust are arranged.

The separator can be used functionally to produce at least the major part of the circulating air flow. To achieve this, the apparatus is characterized in that the separator is formed as a pneumatic centrifugal separator, which is connected with a clean air outlet to a first air fan generating the first fan assembly and is connected via a dust-collecting nozzle with a second fan assembly.

In order to adjust the air flow in such a design and optionally be able to control, the device is preferably characterized in that in the Re inluftausgang and / or at least one adjustable flap for adjusting the passage cross-section of the air flow is arranged between the clean air outlet and the underside of the grate.

As stated above, it is essential that the sump does not overflow. In order to carry out a corresponding automatic control, the device in the described embodiment is preferably characterized in that the filling level sensor controls the delivery rate of at least one of the fan assemblies and / or the position of at least one of the flaps lying in the main air flow.

In order to prevent that the air flow immediately starts with maximum strength during start-up of the device, the filling level sensor in the collecting container is preferably associated with a time delay element delays its effect to delay its action.

The invention will be described in more detail below with reference to an exemplary embodiment with reference to the drawing.

1 shows a longitudinal section through a preferred embodiment,

F i g. FIG. 2 shows a section through the device according to FIG. 1 along the line H-II in FIG. 1.

The device according to the embodiment has a housing 2 with an outwardly open inlet 4 for the bulk material. At the inlet 4 is followed at the bottom of a distribution container 6, on which the bulk material can escape to a slanting downwardly directed grate 8. At the lower end of the distribution container 6, a feed flap 10 is provided, which is urged by a counterweight 12 in the closed position. Due to the opening cross-section, which is limited by the feed flap 10 and automatically changed with varying feed amount, the bulk material passes from the distribution box 6 on the grate 8 and is there viewed through a grate 8 from bottom to top flowing airflow. The heavier grains fall through the grate down onto a sieve assembly 14. Lighter grains and dust are taken up by the air flow. Because of the inclination of the grate 8, a fanning of the bulk material, which also has the consequence that heavier grains are carried along by the air flow upwards, especially when the supply of bulk material is strong. These heavier grains entrained by the airstream pass with the majority of boundary grains into a collecting container 16, which is arranged above the lower end of the grate. The supply flap 10 facing boundary wall 18 of the collecting container is adjustable in height, whereby the proportion of reaching into the collecting container 16 bulk material is roughly adjustable. The proportion in the collecting container depends on the air setting and the position of the boundary wall 18. From the collecting container 16, the bulk material located there passes into a riser sifter 20, which is flowed through by a portion of the air flow from bottom to top. At the lower end of the collecting container 16 is a feed flap 22, which determines the inlet cross section of the collecting container 16 in the riser 20. The two feed flaps 10 and 22 are connected to each other by a coupling rod 24 for simultaneously changing the outlet cross-sections of the distribution container 6 and the collecting container 16 in the same direction.

The space 26 above the grate 8 is closed by two regulating flaps 28, 30, between which a baffle 32 is located. The ascending sifter 20 is closed by a corresponding regulating flap 34.

Downstream of the regulating flaps 28, 30, 34 there is a separator chamber 36 for the lighter grains. A baffle 38 directs the flow of air carrying the lighter grains and dust into the separator chamber 36. The separated lighter grains are discharged by a screw 40.

Downstream of the Separatorraums a pneumatic centrifugal separator 42 is provided, which essentially only the dust with absorbs carrying airflow. The centrifugal separator 42 guides the air flow on the way of an inwardly narrowing screw, with the result that the dust is concentrated in the manner of a layer in the region of the outer wall 44 of the centrifugal separator 42. The dust enters in this way in a nozzle 46, the mouth 47 is arranged tangentially to the inside of the wall. To the nozzle 46, a fan 48 is connected, which removes the dust from the nozzle 46 and conveys into a dust collector, not shown. This also creates a low negative pressure compared to the environment (dust-free!). The Zentrifugalabscheider 42 is operated with two fans 50,52, which are driven by both sides of the housing attached motors 54, 56. The clean air outlet 58 of the centrifugal separator 42 opens into a space 60 below the separator chamber 36, through which the air flow reaches the bottom of the grate 8.

In the clean air outlet 58 is located and a regulating flap 66. Another regulating flap 64 is located in the space 60 below the separator chamber 36.

In the collecting container 16, a level sensor 62 is arranged, preferably a capacitive filling level sensor, which emits a signal corresponding to the level in the collecting container 16. With this signal, the air flow through the grate 8 is controlled. For example, the signal is given to a frequency controller, which regulates the frequency and thus the speed of a fan 48 operating drive motor 68. The control is carried out such that with increasing level in the reservoir 16, the speed of the fan 48 decreases. With decreasing level in the reservoir 16 so the speed of the fan 48 is increased. Accordingly, the air flow that passes through the grate 8 from bottom to top, reduced or increased and thus the fanning of the goods. The coarse adjustment of the circulating air flow can be by hand Adjustment of the flaps 28, 30, 34, 64 and 66 take place, but optionally also be controlled automatically.

Instead of the feeders 10 and 22 and feed wheels coupled to each other variable speed can be provided or coupled feeders adjustable vibrating frequency.

With the level sensor 62, the fans 50, 52 could be controlled or the flaps 64 and 66th

For this 2 sheets of drawings