Power Consuming Turbo-machines P M V Subbarao Professor Mechanical Engineering Department I I T Delhi An expenditure of earnings….

Major equipment in A Power Plant

Structure of A Modern Power Plant

Pump services in Main Steam Cycle Turbogenerator and auxiliaries Condenser circulating pumps Screen wash-water pumps Cooling tower make-up pumps Steam generator equipment Condensate pumps Condensate booster pumps Boiler-feed pumps Boiler-feed booster pumps Deaerator make-up pumps Heater drain pumps (low and high pressure)

Thermodynamic Cycle of air & Gas and flow diagram

Cross-section, single 65,000 hp boiler feed pump, 1300 MW fossil power plant

Expectations from A CondensatePump Duty: Generate Required Open Feed water Heater Conditions ! Condensate Pump Hot Well Rhyd,1 Rhyd,2 Rhyd,n pOFWH+ploss OFWH

Expectations from A Boiler Feed Pump To Generate Required Live Steam Conditions ! plive steam Steam Turbine Rhyd,1 Rhyd,SG Rhyd,n ploss+plive water BF Pump OFWH

Expectations from ID&FD Fan System

Layout of A General Pump

Basic Erection of A Pump STATIC SUCTION HEAD

Basics of A fan

Water Flow Path in A Pump                                                                         

Variation of Absolute Pressure inside A Pump pabsolute Flow Path

Cavitation As the liquid flows onto the impeller of the pump it is accelerated and initially its pressure falls (Bernoulli). The pressure subsequently increases as the fluid leaves the impeller and as the kinetic energy is recovered in the volute chamber. If the pressure of the liquid falls below the vapour pressure, pv, the liquid boils, generating vapour bubbles or cavities-cavitation. The bubbles are swept into higher pressure regions by the liquid flow, where they collapse creating pressure waves and cause mechanical damage to solid surfaces. Moreover, pump discharge head is reduced at flow rates above the cavitation point. Operation under these conditions is not desirable and damages the equipment.

NPSH NPSH

Loss of NPSH

Available NPSH At Site Kinetic power mVs2/2 Frictional loss in suction piping

Classification of Pumps

Machine-Fluid Matching Parameter: For fans For Pumps

DIMENSIONAL ANALYSIS Scale model to prototype design and analysis. Used to select proper turbo-machine (axial, radial or mixed flow,…) Used to define performance parameters

Matching of a Pump/Fan to A Need Speed: N (rpm) or n (rps) This is named as Specific Speed, Ns

Popular Definitions for Pumps The specific speed, usually represented by Ns, also denominated absolute specific speed or specific angular speed.

SELECTION OF SPEED A pump/fan with a given flow geometry and momentum transfer principle

Selection of Geometry Vs Specific Speed

Speed Vs Size : Constant Head & Flow Rate Demand Speed nf = 492 rps N=1000 rpm N=1500 rpm N=3000 rpm

Performance Parameters Differential head of pump:

Non-dimensional Performance Parameters , CH = head coefficient , CQ = flow coefficient , Re = Reynolds number

A similar analysis may be carried out for the power consumption of the pump, P: