Patent GB-468933-A (GB)
Title: Improvements in and relating to elastic fluid turbines
IPC: F01K7/34
Filed: 1937-01-15
Abstract: 468,933. Turbine plant. BRITISH THOMSON-HOUSTON CO., Ltd. Jan. 15, 1937, No. 1279. Convention date, Jan. 15, 1936. [Class 110 (iii)] In a turbine plant consisting of a non - condensing turbine and a further turbine mounted on shafts coupled together, means for automatically supplying elastic fluid to the turbines in series or parallel according to the load conditions are provided. Means for governing the two machines are described. A non - condensing turbine 10 and an extraction turbine 11 coupled together are supplied with steam from conduit 30 through pipes 27, 28. A conduit 33 fitted with non - return valve 34 connects exhaust 13 of turbine 10 to inlet of turbine 11. In pipe 28 is a valve 32 controlled by lever 35 under the action of flow responsive device 37 and pressure responsive device 39. During normal operation the turbines are in parallel, if the flow in conduit 30 decreases the flowresponsive device 37 moves lever 35 downward, valve 32 closes, the pressure in line 29 falls and valve 34 automatically opens. If with the turbines in series more load is required, the shell pressure of turbine 11 rises and pressure responsive device 39 opens valve 32 which automatically closes valve 34. The extraction conduit 15 of turbine 11 is supplied with fluid by branches 16, 17, 18 controlled by valves 19, 20, 21 acting from lever 22 connected to different stages of the turbine. Downward movement of lever 22 opens valves 21, 20 and 19 successively. A governing mechanism for controlling the inlet valves 12, 14 of turbines 10 and 11 and extraction valves 19, 20, 21 is provided. During parallel operation, if demand for extraction fluid from turbine 11 increases, pressure in conduit 15 falls, causing clockwise movement of three-arm lever 57, 58, 59 through pressure responsive device 61. This lever opens valve 14 and valves 19, 20, 21 until the demand is satisfied; the increase in steam flow through the H.P. stages of turbine 11 counteracts the loss in power from the lower stages. A decrease in demand causes a reversal of the process. Increase in demand for elastic fluid from turbine 10 actuates the pressure responsive device 54 to effect clockwise movement of lever 51 about the pivot 52 by means of spring 49, and thus opens valve 12 to satisfy the demand. The resulting increase of power from turbine 10 is counteracted by the lever 51 acting through link 50 causing the lever 48 to move about the end of lever 46 and thus lower the three-arm lever 57, 58, 59 which closes valve 14 and opens valves 19, 20, 21, thus reducing the output of turbine 11 whilst maintaining the pressure in conduit 15. An increase in mechanical load causes the governor to raise lever 46 about pivot 47, move lever 48 and raise three-arm lever 57, 58, 59 in parallel upward movement, thus closing valves 19, 20, 21 and opening valve 14, and increasing the output of turbine 11. A decrease in load causes the reverse to happen until the valve 14 is shut. If the demand still falls, it is desirable to close valve 12. This is effected by placing under the common point 56 of the three-arm lever 57, 58, 59 and lever 48 a stop 63 such that the lever 48 engages stop 63 as soon as valve 14 is shut. The stop 63 then acts as fulcrum for lever 48 and downward movement of lever 46 causes upward movement of left-hand end of lever 48 so that lever 51 is turned counterclockwise to close valve 12. During series operation of the turbines, if the demand for extraction fluid from turbine 11 increases, the pressure in conduit 15 drops and the valves 14 and 19, 20, 21 are opened as before. This causes an increased steam flow from turbine 10 and a fall in pressure in conduit 13 which is compensated by increased opening of valve 10 by pressure responsive device 54. The increase in output of turbine 10 is balanced by the decrease of turbine 11, as the device 54 causes a drop of the lever 51 which causes lever 48 to move about pivot connection with lever 46 thus closing valve 14 and opening valves 19 to 21. The operation of the mechanism in response to changes in demand for fluid from turbine 10 is the same as when the turbines are operated in parallel. An increase in load on the machines causes the speed governor 45 to move lever 46 upwards, and this in turn causes the three-arm lever to move upward and open valve 14 and close valves 19 to 21. The increase in flow through turbine 11 increases its output. Opening of the valve 14 causes a decrease in pressure in conduit 13 which is compensated by an opening movement of valve 12 by the action of pressure governor 54. If the demand for load decreases below a certain value, it is no longer possible to satisfy the demand for extraction fluid from turbine 11, preference is then given to maintaining exhaust pressure of turbine 10. If the load decreases still further after valve 14 is shut and lever 48 is engaged by stop 63, the pressure in conduit 13 cannot be maintained as the valve 12 is closed by the governor 45. The governing movements described above can take place simultaneously.