Design and performance of main vacuum pumping system of SST-1 Tokamak

The first experiments in SST-1

“…Post re-assembly of SST-1 with refurbished and modified subsystems [10][11][12][13], elaborate engineering validations of various sub-systems of SST-1 were meticulously and systematically undertaken to ensure the functional readiness of SST-1 towards physics experiments. The primary objectives of the engineering validation were spread over a total duration of seven months, which focused on (a) establishing the leak tightness (<10 −8 mbar l s −1 ) of the 5 K circuit comprising of all superconducting TF and PF magnets and cold structures [14,15] including the distribution manifolds containing potential breakers and piping inside the cryostat under the envisaged operational scenarios; (b) establishing the leak tightness of the 80 K circuit [8,16] comprising all sections of the thermal shields including distribution manifolds and potential breakers inside the cryostat [17,18]; (c) validating the controlled cooling down of the 5 and 80 K cold masses within the allowable thermal stress without any 'thermal runaway' and with acceptable pressure drops of <200 mbar; (d) validating the high vacuum (<2.0 × 10 −5 mbar) compatibility of the cryostat space [17]; (e) validating the ultra-high vacuum (<1.0 × 10 −7 mbar) compatibility of the assembled vacuum vessel [18,19]; (f) validating the baking compatibility of the assembled vacuum vessel up to 130 ± 10 • C without any hot spots [7]; (g) quantifying the 'dc field errors' resulting from the assembly and alignment of the TF and PF magnet systems; (h) establishing the large number of synchronizations of the signals quantifying the machine parameters; (i) establishing unambiguously the assembled magnet 'quench detection thresholds' in off-normal operations and 'protection' protocols with power supplies in remote fashion; (j) validations and calibrations of essential sensors and diagnostics belonging to both machine control and plasma diagnostics along with their respective signal conditioning and S/N aspects; and (k) validating the machine control platforms with all essential subsystems and diagnostics interfaces and data storage protocols etc. The superconducting magnets being the most critical component to SST-1 have all been individually tested in cold conditions at 5 K in nominal currents of 10 kA in an exclusive test cryostat, together with their flow manifolds and potential breakers in a detailed and systematic fashion, either in supercritical flow or in two-phase flow cooled prior to the device assembly [20].…”

Energy efficiency analysis of steam ejector and electric vacuum pump for a turbine condenser air extraction system based on supervised machine learning modelling

“…Dennis et al [2] have analysed the SEPS by mathematical methods. The LRVP for Tokamak have analysed and designed by Khan et al [3]. Zhu et al [4] and Chong et al [5] proposed a 2D exponential model to predict the velocity distribution in ejector, however the pressure is still assumed to be uniform in the radial direction.…”

“…SCADA [7] contains more than 850 data groups on the operation of a CHP system in thermal power plant and are constantly recorded on an hourly basis 365 days a year. The data on the 2013/2014 inlet diffuser cross sectional area, m 2 c 1 steam speed at the exit from the Laval nozzle, m/s c 2 inlet diffuser mixed gas speed, m/s e in,LRVP amount of specific energy capable of work in the LRVP, kJ/kg e loss,p loss of specific energy capable of work in a specific part, kJ/kg h gas enthalpy, J/kg or kJ/kg h b boiler steam specific enthalpy, kJ/kg h in,p specific enthalpy of a gas mixture to a specific part, kJ/kg h out,p specific enthalpy of a gas mixture from a specific part, kJ/kg h 00 out turbine exhaust steam specific enthalpy, kJ/kg h 0 specific enthalpy of motive steam, J/kg h 1 specific enthalpy of steam Laval nozzle expansion, J/kg h 1s specific enthalpy of steam isentropic Laval nozzle expansion, J/kg h 3 diffuser outlet mixed gas specific enthalpy, J/kg h 3 0 isentropic specific enthalpy of diffuser outlet mixed gas, J/kg h 4 specific enthalpy of pumped gas, J/kg I c investment cost, EUR m non-in mass of the non-condensable gas entering the turbine condenser, kg m non-out mass of non-condensable gas pumped form the turbine condenser, kg m tot-c total mass of the non-condensable gas of the turbine condenser, kg n LRVP impeller speed, rpm p c pressure in the turbine condenser, Pa or MPa p in pressure on the suction side of the LRVP, Pa p out pressure of the pumped gas on the pressure side of the LRVP, Pa p 1, p 4 , p x pressure in the mixing section, Pa p 0 inlet motive steam pressure, Pa p 2 diffuser inlet mixed gas pressure, Pa p 3 exhaust ejector mixed gas pressure, Pa P gen generated power in the case of SEPS motive steam expansion in the turbine, kW P LRVP LRVP power consumption, kW qm non-in mass flow of non-condensable gas penetrating into the turbine condenser, kg/s qm non-out mass flow of the pumped non-condensable gas from the turbine condenser, kg/s qm H 2 O mass flow of the pumped condensable gas, kg/s qm O motive steam mass flow through the Laval nozzle, kg/s qm LRVP masni pretok črpane plinaste zmesi LRVP, kg/s qm 4 pumped gas mass flow, kg/s qV volumetric flow rate of the pumped out gas, m3/h qV non-gas volumetric flow rate of the pumped non-condensable gas, m 3 /h qV H 2 O volumetric flow rate of the pumped condensable gas, m 3 /h R 0 motive steam gas constant, J/(kg K) R mix2 gas constant of the gas mixture in the mixing section, J/(kg K) R n gas constant of the non-condensable gas, J/(kg K) s in,p specific entropy of a gas mixture to a specific part, J/(kg K) s out,p specific entropy of a gas mixture from a specific part, J/(kg K) t time, minute, second T temperature, K T a ambient temperature, K T c temperature in the turbine condenser, K T 0 inlet motive steam temperature, K T 2 diffuser inlet mixed gas temperature, K x 0 motive steam specific heat ratio x mix2 specific heat ratio of the gas mixture in the mixing section P E electric consumed or additionally generated energy at an annual level in case of 6000-h yearly operation heating season is used in the paper. Some other authors also used the SCADA in their research [8][9][10][11][12].…”