Patent GB-822012-A (GB)
Title: Improvements relating to fluid pressure reducing apparatus
IPC: F01K3/00
Filed: 1955-11-23
Abstract: 822,012. Elastic-fluid turbines. GENERAL ELECTRIC CO. Nov. 23, 1956 [Nov. 26, 1954], No. 33616/55. Class 110 (3). [Also in Group XXIX] In fluid pressure reducing apparatus comprising a plurality of pressure reducing units 9a-9g, Fig. 1, in at least two series, each unit consisting of a vortex chamber, and an inlet connected to a supply manifold, there is provided a by-pass conduit with a valve therein for admitting fluid from the manifold to an auxiliary inlet discharging tangentially into the vortex chamber of a unit of one series downstream from the first unit of the other series. General arrangement.-During normal operation steam at a super critical pressure and temperature from the steam generator shown as a " single-pass " heat exchanger 1a and a fuel burner 1b flows to a turbine 2 via a conduit 1c with a stop valve 1e and throttling or control gear 2a; from the turbine the steam traverses a condenser 3, hot-well pump 4 and a conduit 4a before entering a " de-aerating heater " 6 that is connected by a conduit 6a to the electricallydriven boiler feed-pump 5 which leads to the boiler 1 through a conduit 5c. An extraction valve 2c enables steam to be admitted to the heater 6 from a lower pressure turbine stage. A number of heaters may be provided each heated by steam from various points in the flow path through the turbines. Steam may be by-passed around the turbine at starting by apparatus comprising a valve assembly 8, the series-arranged pressure reducing vortex-chambers 9a-9g which exhaust into a de-superheater 10 that is connected to gas-liquid separators 11, 12. The steam pressure is controlled by a pressure regulator 13 whilst a master control 14 is electrically or hydraulically connected to the stop valve 1e, control gear 2a, pressure regulator 13, fuel burner 1b and, if desired, to the feed-pump speed-selector 5b. The low-pressure steam entering the de-superheater 10 from the chamber 9g is sprayed with water from a nozzle 10a at a rate determined by an automatic valve 10b and responsive to a detector 10c sensing temperature in the steam flowing in a conduit 12a to the condenser 3. From the de-superheater 10 the steam and entrained water droplets pass to the centrifugal separator wherein the liquid passes to the second separator 12; the water level in the first separator is maintained by a throttling valve 11c under the control of a level-sensing apparatus 11d; the water passing the valve flashes into steam because of the lower pressure in the steam separator. Steam from the top of the first separator 11 is conducted to the heater 6 and from the second separator enters the condenser 3 via the conduit 12a whilst water from the second separator 12 is forced by a pump 12b into a conduit 4a also connected to the heater 6. All the fluid discharged from pressure reducing chambers 9a-9g is thus returned to the boiler 1 by way of heater 6 and pump 5. Pressure reducing apparatus.-Each vortex chamber, such as 15a, Fig. 2, is cylindrical and with the exception of chamber 9a has an inlet 16 from the previous chamber which is straight and of constant cross-section; the inlet discharges tangentially into the chamber 15a having a conical end or flat end wall 15c whilst each of the chambers 9a-9e also has a conduit 17a-17e, respectively, from the valve assembly 8 opening tangentially thereinto, at right angles to the inlet 16 and downstream but in the same plane as the latter. The chambers 9a-9c are identical except that the discharge 21a from chamber 9c is larger than that of the other two chambers. The size of chambers 9d-9g progressively increases whilst the discharge passages from each is larger than the inlet conduit thereof. The length of each chamber approximates to its diameter and the length of the passages interconnecting the chambers may be between five and ten times the passage diameter. When the by-passed medium is liquid it enters the chambers via conduit 17a but as the nature of the medium changes from liquid to a mixture of liquid and gas the conduits 17a, 16b, 19a and 21b are progressively by-passed by admitting the mediums through the inlets 17b, 17c and 17d. Valve assembly.-A housing 8a, Fig. 1, has an inlet chamber 8b and a shut-off valve 24 for admitting fluid to an intermediate chamber 8c from which a number of valves 25a-25e admit fluid to the conduits 17a-17e. Each valve is actuated by a separate cam 28 and lever 29, only one of each of which is shown; the cam-shaft (not shown), is operated by a rack 31 on a piston device 32 controlled by means 13b associated with the regulator 13. The stop valve 24 is opened first and remains in this position throughout the subsequent operation of the by-pass system; the values 25a- 25e then open in succession each reaching and remaining at its maximum opening before the next one commences to open ; the valve 25e will only open in abnormal circumstances. Operation.-With the stop valve 1e closed and the boiler inoperative the speed of the feed pump 5 is increased to produce the rated discharge pressure of 300 atmospheres and a manual adjusting device 13a on the regulator 13 is set to maintain the pressure at this value. Upon increasing the feed-pump speed the regulator 13 causes the valve 24 to fully open and valve 25a to partially open so that water enters the chamber 9a and then each of the other chambers in turn with a pressure reduction in each chamber, most of the energy in the water being dissipated in the first three chambers 9a-9c; the final temperature at the entry to the de-superheater may be of the order of 7 atmospheres. When the flow rate is a given proportion of that obtained when the boiler is functioning, e.g. one-third to one-quarter the master control 14 permits fuel to be supplied to the burner 1b so that the water temperature rises and the pressure of fluid in the chambers increases thereby causing the inlet pressure to rise above the set 300 atmospheres and valve 25a to open further. The boiler fuel supply is increased until the boiler is supplying steam at the supercritical conditions of 300 atrnosspheres and 621‹ C. under which circumstances the requisite number of valves 25 are completely or partially opened by the piston device 32. The master control 14 now opens the stop valve 1e and actuates the valve gear 2a to admit fluid to the turbine 2; as the flow rate through the turbine increases the control 14 causes the regulator 13 to close the valves 24 and 25a-25e, thus putting valve assembly 8 and pressure reducing chamber 9 out of action; the shutting down of the by-pass system may be effected by the manual device 13a. In either case the object is to maintain constant the total flow from the boiler during transistion from by-pass to turbine operations.