Patent GB-861756-A (GB)
Title: Improvements in or relating to regenerative heat exchangers
Inventor: HODGE JAMES
IPC: F28D17/04
Filed: 1957-07-26
Abstract: 861,756. Valves. POWER JETS (RESEARCH & DEVELOPMENT) Ltd. July 25, 1958 [July 26, 1957], No. 23787/57. Class 135. [Also in Group XXVI]  In a gas turbine plant comprising a regenerative type heat exchanger having two matrix portions, each matrix being positioned alternately in the path of the hot exhaust gases from the turbine and in the path of cooler fluid from the compressor and simultaneously in a different path from the other, a fuel supply control arrangement is provided which comprises a valve in the supply to the combustion system, a mechanism for changing over the matrices and a control interconnection between the mechanism and the fuel valve whereby the fuel supply is reduced after the change-over and is subsequently increased. The plant shown in Fig. 5 comprises a compressor 33, air preheater 30, combustion chamber 35 and turbine 34. The air preheater comprises two matrices A, B mounted on a sleeve 32 which is movable axially on a hollow sleeve 38. The matrices are disposed within a casing which affords chambers 30A, 30B, 30C, 30D, the sleeve and matrices being movable axially by moans of fluid-operated rams 37, 37A. In the position shown, air from the compressor flows through duct 33A to inlet 41, through matrix A where it is preheated, into chamber 30B and then through duct 34A to combustion equipment 35. Exhaust gases from the turbine flow through duct 34B to inlet 42, through matrix B thereby heating it, thence to chamber 30D finally discharging to atmosphere. In the alternative position of the matrices A and B the matrix A is heated by the turbine exhaust gases and air from the compressor is pre-heated in passing through matrix B. A rod 36 is attached to the sleeve 32 and is connected to an arm 3 which is pivoted at 3A, links 1 and 2 being connected to the ends of the arm 3. When the sleeve 32 and so rod 36 are moved to the left, the link is moved to the dotted position shown in Fig. 1, so that the lever 4 is moved to the dotted position 4A. This causes the cam 6 to move in a clockwise direction so that the lobe 6D moves to the position previously occupied by lobe 6A. The lobe engages the spindle 10 of the fuel valve 9 so that the valve is moved to its flow-restricting position against the action of spring 13. The valve is returned gradually to its open position by spring 13, fluid forced into the chamber 14 through the non-return valve 15 during downward movement of the piston 11 leaking gradually back through the restriction 16. When the sleeve 32 is moved in the opposite direction, the link 2 is moved to the right so that the lever 5 is moved from the dotted position 5A to the full-line position 5. This again causes the cam to move clockwise through 90 degrees so that another lobe on the cam actuates the fuel valve to restrict the fuel supply to the combustion chamber. In the embodiment shown in Fig. 2, the fluid that actuates, the matrix structure flows either through duct 19 or duct 20 through non-return valve 19A or 20A to the duct 18, thence through restriction 21 to act on piston 11, so operating the fuel restricting valve 9. The valve is gradually opened by means of spring 13, fluid passing back through restriction 21 and through lead-off valve 29. In the similar arrangement shown in Fig. 3, a cyclic shut-off valve 22 is provided between the conduits 19, 20. The fuel restricting valve 9 is operated similarly to that in Fig. 2. When the pressure of the operating fluid has built up to a certain value dependent on the strength of the springs 25, 26 disposed at either side of the piston 24, the piston will be displaced to one side, thereby closing the valve 27 or 28 so cutting off the supply of operating fluid to the conduit 19 or 20. The valve 9 will then gradually return to its upper position, operating fluid escaping through the leak-off valve 29 as in Fig. 2. This arrangement is used when the operating fluid supply to the pistons 37, 37A is maintained from one changeover to another. In a further embodiment, the changeover mechanism for the heat exchanger is operated electromechanically and the fuel restricting valve is similarly actuated.