SU438879A1 - Powder and bulk solids level alarm - Google Patents

Description

 one

The invention relates to instrumentation and can be used in various industries.

The level indicator of bulk materials is known, which contains a pneumatic reversing actuator probe with a spring-loaded plunger. However, when operating under conditions of sticky, lumpy and other materials, malfunction may occur or the limit switch associated with the probe may be jammed, which significantly reduces the reliability of the instrument. In addition, the presence of an additional node - a limit switch complicates the design of the device.

The proposed alarm device differs in that in the pneumatic cylinder of the plunger drive on the spring side there are two openings, the distance between which exceeds the height of the plunger, one of which is connected to the atmosphere, and the other through a series-connected throttle and a tank with a control chamber of a normally open pneumorel, the output which is connected with the control chambers of the pneumatic cylinder and the normally open valve, and through series-connected resistance and capacity - with the nozzle of the normally open valve and with the control boiling chamber normally closed pneumatic relay, the output of which is connected to a pressure indicator.

The drawing shows a schematic diagram of the detector.

The indicator consists of a mounting flange 1 and a pneumatic cylinder 2, inside which

a spring-loaded plunger 3 is located with a piston 4 and a rigid probe 5 at the end.

The control block of the plunger contains a normally open three-membrane pneumorel 6, an adjustable choke 7, capacity 8,

normally open two-membrane pneumatic valve 9, adjustable throttle 10, container 11 and normally closed three-membrane pneumorel 12. As a pressure indicator, for example,

a pressure gauge 13 connected by a remote transmission tube with an outlet of the pneumorel 12. The connection of the elements among themselves is shown in the diagram. The indicator works in the following sequence.

In the initial period, the air pressure signal Pi 1 is generated at the outlet of the pneumoregle 6, under the influence of which the lower valve nozzle 9 is closed, and the piston 4 with the plunger 3 and the probe 5 moves to the left as far as it goes in the absence of bulk material before the probe 5. In this case, the piston 4 takes the between two m. additional holes in the wall of the cylinder. Air under pressure

P (1 (for example, 1.4 kgf / cm2) through the choke

7 and the container 8 enters the lower chamber of the pneumatic discharge chamber 6 until the pressure in the lower chamber of the relay does not exceed the pressure in its upper chamber.

The adjustable choke 10 is adjusted to a lower conductivity of the chokes 7 (approximately 2-3 times), so that at the moment of switching the relay 6, the output of the relay 12 remains at atmospheric pressure. When the relay 6 is switched, its output signal, under the influence of the spring, the piston returns to the right in the initial state. Air from the control chamber of the relay 6 through the tank 8 and the throttle 7 and through the third hole in the wall of the pneumatic cylinder enters the atmosphere. The lower nozzle of the valve 9 is opened and in the upper control of the valve, the chamber of the relay 12 is set to atmospheric pressure, at the output of the relay .12 pressure Pt Q.

With a sufficient pressure drop in the lower chamber of the relay 6, pressure Pt reappears at its output, the cycle of movement of the probe 5 to the left repeats. The frequency of the strokes of the piston 4 and the probe 5 is determined by the setting of the throttles 7. If during the next course to the left the probe 5 encounters an obstacle in the form of syvuch material, the piston 4 stops in the position to the right of the hole in the wall of the cylinder connected to the throttle 7. At this time air under pressure PI through the throttle 10 enters the upper chamber of the relay 12. As soon as the pressure in this chamber exceeds the backpressure pressure, a pressure signal appears at the output of the relay, fixed by a pressure gauge 13. This pressure remains until the prep t probe before probe 5

and the powder will not reach the leftmost position. When this occurs, the change in Pt to Pt 0 in the order described above occurs. At the output of relay 12, a pressure is set at P0, the cyclic movements of the probe are restored.

Valve 9 prevents the accumulation of air pressure in the upper chamber of relay 12 and ensures a clearer operation of the entire circuit.

The detector can be installed both outside and inside the tank, in a horizontal, inclined and vertical position.

Subject invention

A powder level and bulk material level detector comprising a reversible pneumatic actuator with a spring-loaded plunger, characterized in that, in order to improve the reliability of the signaling device, two holes are provided in the pneumatic cylinder of the plunger drive, the distance between which exceeds the plunger height, one of them connected to the atmosphere, and the other through a series-connected choke and capacitor with a control chamber of a normally open pneumorele, the output of which is connected to the control chambers Pneumodyne and normally open valve, and through series resistance and capacitance - with the nozzle of the normally open valve and with the control chamber of the normally closed pneumoregle, the output of which is connected to the pressure indicator.

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