Patent GB-691699-A (GB)
Title: Installation for the production of hot gases under pressure
IPC: C21B9/10
Filed: 1950-11-09
Abstract: 691,699. Gas turbine plant centrifugal compressors. SOC. ANON. J. COCKERILL. Nov. 9, 1950 [Nov. 10, 1949], No. 27447/50. Class 110(i) and 110(iii) In a plant for the production of hot compressed gas comprising a first circuit including a compressor, a heat exchanger, a turbine and a reheater connected in series by pipes, the turbines driving the compressor through a first shaft, and a second circuit including a compressor, a combustion chamber, heat exchangers and three turbines, one of the three turbines is arranged on the first shaft and the compressor and the remaining turbines are connected to a second shaft and one of the turbines on the second shaft receives the whole of the gas from the combustion chamber and the other two turbines receive equal portions of the exhaust gas from this turbine. All of the turbines and all of the compressors are of substantially identical construction. The blast of a blast furnace is compressed in a compressor C1, heated in a heat exchanger E by the exhaust combustion gases of two turbines T3, T4, further heated in a heat exchanger R1, by combustion gases from a combustion chamber Ch, then expanded in a turbine Tl to the blast pressure and finally heated in a heat exchanger R2 by the combustion gases from the combustion chamber. The combustion chamber is fed with fuel and air by two compressors C2, C3, which are driven by the turbines T2, T4. The plant is arranged so that under normal operation the output of blast and combustion products from the chamber Ch, the pressure at the discharge of the compressors Cl, C2, and the pressures at the exhaust of the turbines T1 and T2, are equal. It is stated that if the pressure at the exhaust of the turbines T1 and T2 is fixed at approximately two atmospheres and the pressure at the discharge of the compressors selected so that the volume of gas leaving the turbine T2 is twice that entering the turbine, then a common design of turbine may be used for the turbines T2, T3 and T4. Further, if the blast and the combustion gases have the same specific volume under the same conditions of temperature and pressure, this design of turbine may also be used for the tubine T1 The plant is started by rotating shaft II by means of a motor d, with the valve V1 closed. At a given speed, the fuel and air in the combustion chamber are ignited and the motor d uncoupled. When the shaft 11 reaches its normal speed, the valve V1 is opened and the shaft I rotated by the turbine T3. The rotational speed of the shaft I is controlled by a governor S1 which operates a valve VR1 so as to regulate the inlet temperature to the turbine T1. The rotational speed of the shaft II is controlled by a governor S2 controlling the fuel supply to the combustion chamber Ch. The temperature of the blast is controlled by a thermostat S3. which regulates a by-pass valve VR2 for the combustion gases passing through the heater R2. The pressure of the blast may be controlled by a non-return valve V2 in a by-pass connecting the discharge of the turbine T1 with the inlet to the turbine T3. An increase of pressure at the point 5 allows the blast to pass into the inlet of the turbine T3. The compressor C1 may be of the type having three double entry centrifugal wheels mounted on a single shaft, one of the two outer wheels being arranged to discharge into one side and the other into the other side of the central wheel. The compressors C2 and C3 may be combined into a single compressor similar to that described above but in this case the central wheel has a median wall which maintains the two flows separate. It is also stated that the wheels other than the central wheel can be of the single entry type and the number of these wheels is not limited to two. An embodiment in which compressors of this type are employed is described. In this embodiment the combustion temperature is controlled by diluting the fuel gas at entry to the compressor C3 with cooled combustion products from the exhaust of the turbines T3, T4. A valve in a conduit connecting these two points is controlled by the governor S2.