Patent GB-740118-A (GB)
Title: Improvements in or relating to apparatus for storing and transporting powdered material
Inventor: ELLIS STANLEY PETER JOHN
IPC: B65G53/12
Filed: 1954-03-04
Abstract: 740,118. Pneumatic conveyers. BLAW KNOX, Ltd. March 4, 1954, No. 6389/54. Class 78 (1). Apparatus for storing and transporting powdered material comprises a blowing chamber 4 having an inlet 3 and an outlet 6, a storage chamber 1 in communication with the inlet 3 having a sloping bottom 5 composed of porous material through which low pressure air is blown to fluidize the material, a valve 7 for controlling the flow of material from the chamber 1 to the chamber 4, a valve 54 controlling the admission of air to the chamber 4 to blow the material through the outlet, means whereby the apparatus changes from filling to blowing after a predetermined delay period, means whereby the operation of the two valves will be reversed on an emptying of the chamber 4 to allow refilling, a master control valve 41 for the operation of the apparatus and means for ensuring that the apparatus will continue to operate until the chamber 4 is emptied irrespective of whether said master control is moved to the shut-off position either during filling or blowing of the chamber. The hollow valve head 7 has a perforated bottom 7A and is carried by a hollow stem 8 which opens at its upper end into a cylindrical chamber 12. This chamber is connected by a pipe 21 to a pipe 10 through which air is delivered to blow the material from the chamber 4. The chamber 12 communicates through an orifice 13 controlled by a valve 15 with a chamber 14 open to atmosphere. The valve 15 is urged downwards by a spiing 15A and its stem 16 is pivoted to the end 17A of a lever 17, the end 17B of which is pivotally connected to the piston-rod 19 of a pneumatic ram 20. The cylinder 22 of the ram is connected at its ends by a pipe 24 and pipes 26, 27 to the ports 28, 29 of a piston and cylinder type change-over valve 25. The cylinder has exhaust ports 30, 31 and an inlet port 32 for high pressure air. The valve has pistons 34, 35, 36 of the same diameter and a larger piston 37. The upper end of the valve communicates with an air reservoir 38 and the lower end is connected by pipe 39, diaphragmoperated valve 40, pipe 39A and a main air valve 41 with the high pressure air supply pipe 33. The valve 41 can be moved to connect pipe 39A with an exhaust port 41A instead of to the pipe 33. The valve 40 consists of a diaphragm 42 which forms one wall of a chamber 43 and is connected centrally to a valve member 44 for connecting the pipe 39 either to the pipe 39A or to an exhaust port 49. A pipe 46 connects the chamber 43 to the pipe 10. The pipe 39 is connected to the reservoir 38 by a pipe 47 and a bleed valve 48 which permits restricted flow of air into the reservoir when the pressure in pipe 39 is greater than the pressure in the reservoir and permits relatively, but not completely, unrestricted flow from the reservoir when the valve 40 is set to connect pipe 39 to exhaust port 49. A pipe 50 for the supply of low-pressure air is connected by a three-way valve 51 either to a pipe 52 or pipe 53. The pipe 52 communicates via a pneumaticallyoperated valve 54, operated in accordance with the pressure in the pipe 26, with the pipe 10. The valve 54 is opened only when the pipe 26 is connected to the pipe 33. The pipe 53 supplies air to the space below the porous bottom 5 and communicates with the pipe 52 via a pneumatically-controlled valve 55 which is opened only when the pressure in the pipe 24 is high. When the working parts are disposed as in the Figure, high-pressure air passes from the pipe 33 to the cylinder 22 to force down the piston 23 and 'maintain closed the inlet 3. Lowpressure air is supplied to the pipe 53 and the material in the container 1 is fluidized. The valve 54 is open since it is exposed to highpressure air. Automatic filling and discharging of the chamber 4 is initiated by opening the valve 41 and turning the valve 51 to admit low pressure air to the pipe 52. High-pressure air now passes through the pipes 47, 39, thereby causing the pressure in the reservoir 38 to build up relatively slowly and the pistons 34 ... 37 to move upwards whereby pipe 24 is put into communication with high pressure air supply and pipe 27 is connected to exhaust. In consequence the piston 23 rises and the valve 7 opens. When the hollow stem 8 moves down, the valve 15 disengages from its seating and the stem becomes supported by the spring 15A. The air displaced from the chamber 4 by the entry of material passes through the stem 8 and chambers 12, 14 to exhaust. When the chamber 4 is full and pressure in the reservoir 38 has risen sufficiently to cause downward movement of the pistons 34 ... 37, the pipe 24 is connected to exhaust and the pipe 27 to the high-pressure air supply. The piston 23 now moves down and the valve 7 closes the inlet. The valve 55 is closed and the valve 54 opened so that low-pressure air passes to the chamber 4 through the pipe 10 and stem 8 and discharges the material through the outlet 6. Pressure builds up in the pipe 10 and pressure in chamber 43 rises sufficiently to enable the diaphragm 42 to overcome the opposition of the spring 45 and change the position of the valve 40, so that the pipe 39 is connected to exhaust and the reservoir 38 is discharged. Air continues to pass into the chamber 4 until it is empty. The pressure in the chamber 43 then falls and the spring 45 moves the valve 40 to connect the pipes 39, 39A and the sequence of operations recommences.