Fluid Pumps PDF

TRANSPORTATION AND METERING OF FLUIDS PUMPS Week # 9 Dr. Zohaib Atiq Khan Assistant Professor [email protected] Department of Chemical, Polymer & Composite Materials Engineering...

TRANSPORTATION AND METERING OF FLUIDS PUMPS Week # 9 Dr. Zohaib Atiq Khan Assistant Professor [email protected] Department of Chemical, Polymer & Composite Materials Engineering (New Campus) 1 CHAPTER 8 Week 8 Summary 1. PIPE AND TUBING 2. JOINTS AND FITTINGS 3. PREVENTION OF LEAKAGE AROUND MOVING PARTS 4. VALVES Book W. L. McCabe, J. C. Smith, and P. Harriott, Unit Operations of Chemical Engineering, 5th Ed, McGraw-Hill: 2004. UET 2 LAHORE Copyright ® Dr Zohaib Atiq Khan CHAPTER 8 TRANSPORTATION AND METERING OF FLUIDS 1. ABOUT PUMPS 2. BASIC COMPONENTS OF PUMPS 3. HOW PUMP WORKS 4. PUMP OPERATION 5. PUMP MAINTENANCE Book W. L. McCabe, J. C. Smith, and P. Harriott, Unit Operations of Chemical Engineering, 5th Ed, McGraw-Hill: 2004. UET 3 LAHORE Copyright ® Dr Zohaib Atiq Khan TRANSPORTATION AND METERING OF FLUIDS PUMPS “Pump is a machine that imparts energy to the liquid”. Why are Pumps Required? Move liquids from lower elevation to higher elevation Move liquids from lower pressure areas to areas of higher pressure Increase the flow rate of a liquid UET 4 LAHORE Copyright ® Dr Zohaib Atiq Khan TRANSPORTATION AND METERING OF FLUIDS PUMPS CLASSIFICATION CENTRIFUGAL KINETIC PUMPS AXIAL FLOW TRIBINE PUMP PUMPS RECEPROCATING POSITIVE DISPLACEMET PUMPS ROTARY METERING UET 5 LAHORE Copyright ® Dr Zohaib Atiq Khan TRANSPORTATION AND METERING OF FLUIDS CENTRIFUGAL PUMP Employ centrifugal force and velocity to create pressure. The inlet flow to the pump is directed into the center of the spinning impeller Centrifugal force throws the liquid at high velocity into the surrounding casing or “ volute.” The special shape of the volute converts high velocity into pressure. UET 6 LAHORE Copyright ® Dr Zohaib Atiq Khan TRANSPORTATION AND METERING OF FLUIDS AXIAL FLOW PUMP The rotating element is a simple propeller mounted in a pipe or open tank. The inlet flow to the pump is directed into the center of the spinning impeller The pitched blades of the propeller move liquid axially, in the same way that a ceiling fan moves air. Produce very high volumes but low head pressure. UET 7 LAHORE Copyright ® Dr Zohaib Atiq Khan TRANSPORTATION AND METERING OF FLUIDS TURBINE PUMP Suction flow enters the channel at the inlet point and is picked up by the buckets to start the journey around the channel. As the liquid travels through the channel, a spiral action is set up that compounds the pressure. Pressure rapidly builds until the liquid is diverted from the channel at the discharge. UET 8 LAHORE Copyright ® Dr Zohaib Atiq Khan TRANSPORTATION AND METERING OF FLUIDS RECIPROCATING PUMPS Piston Pumps Reciprocating Pumps Plunger Pumps Diaphragm Pumps UET 9 LAHORE Copyright ® Dr Zohaib Atiq Khan TRANSPORTATION AND METERING OF FLUIDS RECIPROCATING PUMPS F:\EPCL Data\TTS\Pumps HTML\pump1_4testfix_bold.jpg Alternately takes in a quantity of liquid and then displace it to build pressure in pulsating cycles. Pumping element is either a piston, a plunger, or a diaphragm that travels in a back-and-forth motion. Used to build high pressure up to 1500 atm. Double acting pumps are used to avoid pulsation Simplex/duplex arrangement is used in industries UET 10 LAHORE Copyright ® Dr Zohaib Atiq Khan TRANSPORTATION AND METERING OF FLUIDS DIAPHRGAM PUMPS Uses a combination of the reciprocating action of a rubber or Teflon diaphragm and suitable non- return check valves to pump a fluid. Used for corrosive fluids and highly viscous fluids Generates high pressure up to 1200 bar High efficiency up to 97% UET 11 LAHORE Copyright ® Dr Zohaib Atiq Khan TRANSPORTATION AND METERING OF FLUIDS ROTARY PUMPS GEAR PUMP Trap and displace liquid as the pumping element rotates. Liquid may be trapped between the teeth of gears (in a gear pump); or, between vanes (in a vane pump); or, around a cam (in a cam pump). UET 12 LAHORE Copyright ® Dr Zohaib Atiq Khan TRANSPORTATION AND METERING OF FLUIDS ROTARY PUMPS F:\EPCL Data\TTS\Pumps HTML\pump1_6_thru_9_testfix_bold.jpg F:\EPCL Data\TTS\Pumps HTML\pump1_6_thru_9_testfix_bold.jpg UET 13 LAHORE Copyright ® Dr Zohaib Atiq Khan TRANSPORTATION AND METERING OF FLUIDS VANE PUMP http://www.hammer-alleviators.com/images/vane-pump.gif UET 14 LAHORE Copyright ® Dr Zohaib Atiq Khan TRANSPORTATION AND METERING OF FLUIDS PLUNGER PUMP http://www.hammer-alleviators.com/images/packed-plunger-efficiency.gif UET 15 LAHORE Copyright ® Dr Zohaib Atiq Khan TRANSPORTATION AND METERING OF FLUIDS LOBE PUMP http://www.hammer-alleviators.com/images/lobe-rotary-piston.gif UET 16 LAHORE Copyright ® Dr Zohaib Atiq Khan TRANSPORTATION AND METERING OF FLUIDS METERING PUMPS Used to meter precise quantities of liquid flow A metering pump is usually used to add chemical additives to a process in precise proportions. Capability of maintaining an accuracy of flow without the use of flow control valves UET 17 LAHORE Copyright ® Dr Zohaib Atiq Khan TRANSPORTATION AND METERING OF FLUIDS Parts of Centrifugal Pumps UET 18 LAHORE Copyright ® Dr Zohaib Atiq Khan TRANSPORTATION AND METERING OF FLUIDS Impeller Impeller is the heart of Centrifugal Pump It rotates the liquid mass with the peripheral speed of its vane tips. The whirling movement of Impeller imparts centrifugal force to the liquid and increases the velocity head. Impeller does not increase liquid pressure. High velocity head is converted to pressure head in the volute. Increase in velocity is directly proportional to Impeller diameter & Pump speed. UET 19 LAHORE Copyright ® Dr Zohaib Atiq Khan TRANSPORTATION AND METERING OF FLUIDS Parts of Impeller Impeller Hub Wear Rings Suction Eye Impeller shroud Impeller Vanes UET 20 LAHORE Copyright ® Dr Zohaib Atiq Khan TRANSPORTATION AND METERING OF FLUIDS Impeller Types based on construction ❖ Consisting of Vanes only ❖ Shroud on one side only ❖ Shroud on both sides ❖ No shrouds or sidewalls ❖ Liquid slippage exists but ❖ Least Liquid slippage less than in open type ❖ Liquid slippage exists ❖ Greater liquid velocity ❖ Greater liquid velocity than other types ❖ Relatively less liquid than open type velocity ❖ Applied in pumps ❖ Applied in pumps handling handling clear liquids ❖ Impeller has structural abrasive liquids weakness ❖ Applied in pumps handling slurries & mud UET 21 LAHORE Copyright ® Dr Zohaib Atiq Khan TRANSPORTATION AND METERING OF FLUIDS Impeller Types based on suction UET 22 LAHORE Copyright ® Dr Zohaib Atiq Khan TRANSPORTATION AND METERING OF FLUIDS Pump Casing Enclosed space where the impeller rotates with the shaft Converts velocity of liquid into pressure Has close clearance with the impeller Has two ends, Suction & Discharge Casing Types: Single Volute Case Double Volute Case UET 23 LAHORE Copyright ® Dr Zohaib Atiq Khan TRANSPORTATION AND METERING OF FLUIDS Pump Shaft The basic function of a centrifugal Pump shaft is to transmit the torques encountered in starting and during operation. It also supports the impeller and other rotating parts. Impeller Gland Packing / Mech Coupling Seal O/B Bearing I/B Bearing SHAFT SLEEVE: The basic function of the sleeve is to protect shaft from erosion, corrosion and wear at stuffing boxes, leakage joints & internal bearing areas. UET 24 LAHORE Copyright ® Dr Zohaib Atiq Khan TRANSPORTATION AND METERING OF FLUIDS Pump Bearings Allow the shaft to rotate with practically negligible friction. Hold the rotating element in its proper position relative to the stationary parts of the pump, both radially and axially, so that the rubbing cannot occur. Be able to absorb forces that are transmitted to them from the impeller. Give trouble free service for long periods of time UET 25 LAHORE Copyright ® Dr Zohaib Atiq Khan TRANSPORTATION AND METERING OF FLUIDS Axial or thrust load Radial Load Angular Load UET 26 LAHORE Copyright ® Dr Zohaib Atiq Khan TRANSPORTATION AND METERING OF FLUIDS Balancing Drum UET 27 LAHORE Copyright ® Dr Zohaib Atiq Khan TRANSPORTATION AND METERING OF FLUIDS Balance Drum In any centrifugal pump, each impeller tends to produces some amount of thrust because of different pressures and different geometries on the two sides of the impeller. In a high pressure multi-stage pump (such as BFW) the number of impellers is high, thus the net thrust would be large unless something is done to balance it out. The two main ways to reduce the net thrust are to oppose the impellers or to use a balance drum. UET 28 LAHORE Copyright ® Dr Zohaib Atiq Khan TRANSPORTATION AND METERING OF FLUIDS Couplings Flexible Coupling A Flexible coupling is a device that connects two shafts while allowing for the minor misalignment (angular, parallel or a Rigid Coupling combination) A coupling that permits neither radial nor axial relative motion A flexible coupling must also permit some lateral float of the shafts so that the two between the driving and driven shaft ends may move closer or farther apart shaft is called Rigid Coupling under the influence of thermal expansion UET 29 LAHORE Copyright ® Dr Zohaib Atiq Khan TRANSPORTATION AND METERING OF FLUIDS Pump Basic Principle Head is the height of liquid Suction Lift exists when the source of supply is below the center line of the pump. Static Suction Lift is the vertical distance in feet from the centerline of the pump to the free level of the liquid to be pumped. Suction head exists when the source of supply is above the centerline of the pump. Static suction head is the vertical distance in feet from the centerline of the pump to the free level of the liquid to be pumped. UET 30 LAHORE Copyright ® Dr Zohaib Atiq Khan TRANSPORTATION AND METERING OF FLUIDS Pump Head Static discharge head is the vertical distance in feet between the pump centerline and the point of free discharge or the surface of the liquid in the discharge tank. Total static head is the vertical distance in feet between the free level of the source of supply and the point of free discharge or the free surface of the discharge liquid. UET 31 LAHORE Copyright ® Dr Zohaib Atiq Khan TRANSPORTATION AND METERING OF FLUIDS LIFT & HEAD CONCEPT UET 32 LAHORE Copyright ® Dr Zohaib Atiq Khan TRANSPORTATION AND METERING OF FLUIDS Question: Will Different Density Liquids Pump to the Same Level (As Shown Here) or: ? S.G.- 1.2 S.G.- 1.0 S.G.- 0.7 UET 33 LAHORE Copyright ® Dr Zohaib Atiq Khan TRANSPORTATION AND METERING OF FLUIDS Or Will They Pump to Different Levels as Shown Here? S.G.- 1.2 S.G.- 1.0 S.G.- 0.7 UET 34 LAHORE Copyright ® Dr Zohaib Atiq Khan TRANSPORTATION AND METERING OF FLUIDS Answer: They Will Pump to the Same Height (Head) but Will Show Different Pressure Gauge Readings. H=115ft H=115ft 60 psi 50 psi 35 psi S.G.- 1.2 S.G.- 1.0 S.G.- 0.7 UET 35 LAHORE Copyright ® Dr Zohaib Atiq Khan TRANSPORTATION AND METERING OF FLUIDS NPSH Liquids can flash into vapor near boiling point which depends on pressure. In the suction of the pump impeller eye, there may be lower pressure (or vacuum) Ps created due friction losses and sucking by the impeller. S If the liquid flashes, pump performance will be affected NPSH is a related subject to solve this problem. UET 36 LAHORE Copyright ® Dr Zohaib Atiq Khan TRANSPORTATION AND METERING OF FLUIDS Net Positive Suction Head (NPSH) NPSH Available: Absolute pressure at the pump suction, changed into head minus the vapor pressure of the liquid being pumped, changed to head. NPSH Required: Minimum head needed at the suction to get the liquid into the impeller without vaporizing NPSHa > NPSHr NPSH = Ha ± H – H – Hf + H Z v velocity Ha Absolute pressure head at reservoir surface Hz Elevation head/lift at pump suction Hv Vapor Pressure head of liquid at pump suction Hf Friction Head in inlet pipe UET 37 LAHORE Copyright ® Dr Zohaib Atiq Khan TRANSPORTATION AND METERING OF FLUIDS NPSH of Vacuum System In the vacuum system like surface Vacuum condensers, you will find either the level is high/the equipment is elevated and some cases the pump is S M under the ground to meet the required NPSH. Example: condensate pump UET 38 LAHORE Copyright ® Dr Zohaib Atiq Khan TRANSPORTATION AND METERING OF FLUIDS Net Positive Suction Head Available Case 1 Positive Suction from an open tank. UET 39 LAHORE Copyright ® Dr Zohaib Atiq Khan TRANSPORTATION AND METERING OF FLUIDS Net Positive Suction Head Available Case 2 Suction lift from a reservoir below pump UET 40 LAHORE Copyright ® Dr Zohaib Atiq Khan TRANSPORTATION AND METERING OF FLUIDS To Increase the NPSHa Raise the suction tank (or level in the tank). Lower the pump. Increase the pressure in the suction tank. Cool the liquid to reduce vapor pressure. Modify the suction piping. - Increase pipe diameter Reduce the length - change fittings - modify valve type - reduce number. UET 41 LAHORE Copyright ® Dr Zohaib Atiq Khan TRANSPORTATION AND METERING OF FLUIDS Power and Efficiency Brake horsepower (bhp) Actual horsepower delivered to the pump shaft Hydraulic horsepower (whp) The liquid horsepower delivered by the pump UET 42 LAHORE Copyright ® Dr Zohaib Atiq Khan TRANSPORTATION AND METERING OF FLUIDS Performance Curve/System Curves The performance curve is actually four curves resulting with each other on a common graph. These four curves are: The Head-Flow Curve The Efficiency Curve The Energy Curve The Pump’s Minimum Requirement Curve UET 43 LAHORE Copyright ® Dr Zohaib Atiq Khan TRANSPORTATION AND METERING OF FLUIDS Performance Curve/System Curves 265 mm 20% 60 40% 245mm 50 40% 225 mm Best Efficiency 20% 40 85% Head (m) 265mm 20 245 mm 15 225 mm 10 kW 6 NPSH 4 NPSHR 2 0 5 10 15 20 25 30 35 40 45 Capacity (m3/hr) UET 44 LAHORE Copyright ® Dr Zohaib Atiq Khan TRANSPORTATION AND METERING OF FLUIDS Performance Curve/System Curves UET 45 LAHORE Copyright ® Dr Zohaib Atiq Khan