Patent GB-131183-A (GB)
Title: Improvements in and relating to Centrifugal Compressors.
IPC: F04D27/02
Filed: 1918-09-05
Abstract: 131,183. British Thomson - Houston Co., (General Electric Co.). Sept. 5, 1918. Regulating.-A centrifugal air-compressor having a constant volume governor mechanism set by a motor is provided with means whereby the motor is controlled from a distance together with means for indicating at the distant point the setting of the governor. An automatic arrangement for controlling the operation of pulsation-preventing mechanism of the by-pass valve type is also described. The figure shows diagrammatically. the apparatus applied for the supply of air from a compressor 12 driven by a turbine 13 to a converter 1 for metal smelting through a pipe 5. The governor mechanism is of a known kind comprising a float 20 in the compressor inlet connected to a pivoted beam 16 along which a weight 18 is moved by turning a screw 19. The beam is connected to the ordinary centrifugal governor 26 through links, and also to ordinary supply valve mechanism 29 for the turbine through links, and works in a known manner to control the, fluid supply to the turbine, and therefore the compressor output, according to the setting of the weight 18 in relation to the beam 16. The turbine and compressor are located away from the converter, and it is desirable for the operator at the converter to control the compressor output according to conditions at the converter, and also to receive indications of the setting of the governor mechanism. This is accomplished by providing a motor 34 carried by the beam 16 and having two separate field windings for moving the weight 18 in either direction by rotating the screw 19 through worm gearing. A magnetic brake 37 stops the motor when both field windings are out of circuit. Leads 39, 40 connect the two field windings to a switch 44 located in the converter house so that a power lead 43 may be connected to either field winding at will. Contacts 45, 46 in the leads 39, 40 are opened at the ends of the travel of the weight 18 by insulated fingers 48, 49 carried by the weight to prevent overtravel of the weight in either direction. A contact arm 47 on the weight travels over a contact bar 50 and over a series of insulated contacts 53 to complete indicating circuits of a series of lamps 55 in the converter house showing the position of the weight 18 on the balance beam. If desired, an indication of the corresponding volume of flow may be marked adjacent to each lamp 55. In some cases where the output is required to increase to a definite amount in a given time, the motor may be regulated to work continuously and move the weight on the balance beam through the necessary distance in the given time. For this purpose, a simple rheostat or other suitable means may be used with the switch 44 for controlling the motor speed. An automatic electric control means for pulsation-preventing apparatus of the by pass-valve type to be worked in combination with the means for setting the weight 18 on the balance 'beam comprises two electric contact controllers 63, 70 and a double field wound motor 59 which actuates the by pass valve 58 through worm gearing. The controller 63 comprises a pivoted arm 64 rotated by the valve stem 60 of the by-pass valve 58 and the controller 70 comprises a pivoted arm 71 rotated by the engagement with it of one of two stops 74, 75 on another pivoted arm 73 when the weight 18 on the balance beam is in a position to push the bar 77. When the weight 18 is moved so far to the right that the compressor output is so small that pulsations are likely to occur, the weight 18 moves the rod 77 to the right and tilts the, arm 73 so that the contact pin 75 is moved into contact with the arm 71. A circuit is thus closed from the power lead 71<a> through the arm 71, pin 75, lead 80, contact strip 70, the upper insulated portion of the arm 71, contact segment 85<a>, lead 85 to the controller 63 at the contact segment 85b, upper insulated portion of the arm 64, contact strip 67, and lead 66 to one field winding of the motor 59 which then rotates in a direction to open the bypass valve 58 and so stop the pulsations. The rotation of the valve stem 60 during this process moves the contact arm 64 out of contact with the segment 85b on to segment 86b. This breaks the circuit of the motor 59 just described and stops the motor, the valve 58 remaining slightly open. If the weight 18 is moved further to the right the contact arm 71 of the controller 70 is moved over further into contact with the segment 86a and a circuit similar to that already described is closed to cause the motor 59 to open the valve 58 further, and the same applies to a further movement of the controller arms 64 and 71 on to contact segments 87b, 87a respectively. If the weight 18 on the balanced lever 16 moves to the left to increase the compressor output the pulsation-preventing valve 58 is gradually closed as follows :- The rod 77 moves to the left and the spring 76 acting on the arm 73 moves the pin 74 into contact with the arm 71. Assuming that the arm 71 is then in a position touching contact segemnt 84<a>, and the arm 64 is in a position touching the contact segment 84b, a circuit is closed from the power lead 71<a> through the arm 71, the pin 74, lead 78, contact strip 79, intermediate part of the arm 71, contact segment 84<a>, lead 84 to the controller 63 at the segment 84b, intermediate part of the arm 64, contact strip 69, and lead 68 to the reverse winding of the motor 59 which rotates to close the valve 58 in stages similar to the opening stages.