overview of rotating equipment.pdf

© John Crane

Overview of Rotating EquipmentSpeaker’s name

Speaker’s role

date

John Crane CopyrightThe information contained in, or attached to, this document, contain confidential information that is proprietary to John Crane.

This document cannot be copied for any purpose, or be disclosed, in part or whole, to third party without the prior approval of John Crane.

© John Crane

Session Agenda:

1. An Overview of Rotating Equipment 2. Prime Movers – Drivers3. Rotating Equipment – Driven4. Connectors – Modifiers & CouplingsFurther Rotating Equipment:5. Centrifugal Pumps6. Positive Displacement Pumps7. Summary and Conclusions

An Overview of Rotating Equipment

© John Crane

Introductory Exercise

Driver DrivenCompressors

MixersWind Turbines

Hydraulic MotorsFans

Steam TurbinesScrew Pumps

Reciprocating PumpsDiesel EnginesElectric Motors

Can you already identify the machineslisted below as Drivers or Driven Equipment?

© John Crane

1. An Overview of Rotating Equipment

In most cases energy is transferred into rotating equipment, from a driving equipment (known as the Prime Mover) to the driven equipment (known as Rotating Equipmentor the Functional Machine).

Examples of Prime Movers include:

Turbines – Steam, Gas, Water & WindInternal Combustion EnginesElectric Motors

Examples of Rotating Equipment include:

Centrifugal and Positive Displacement PumpsCompressorsAgitators/Mixers/ReactorsElectric Generators and AlternatorsFans and Blowers

PrimeMover

(Driver)

Rotating Equipment

(Driven)

© John Crane

Typical rotating equipment fitted with mechanical seals includes:• centrifugal and positive displacement pumps• centrifugal gas compressors and refrigeration compressors• turbines (steam, gas, water, wind)• agitators / mixers / reactors• anywhere a rotating shaft passes through a stationary housing where

product has to be contained

1. An Overview of Rotating Equipment

© John Crane

The term turbomachinery describes machines that transfer energy between a rotor and a fluid, including both turbines and compressors.

A turbine transfers energy from a fluid to a rotor.

A compressor transfers energy from a rotor to a fluid.

2. Prime Movers – Turbomachinery

Typical Steam Turbine Typical Centrifugal Gas Compressor

© John Crane

2. Prime Movers – Steam Turbines

Steam turbines work on the principle of using pressurised steam to rotate turbine blades.

This rotation is then used to drive other equipment, in a similar way as an electric motor but utilising the heat and pressure of the steam rather than electricity as the driving energy.

© John Crane

2. Prime Movers – Gas Turbines

Gas turbines work on the principle of using pressurised fuels to rotate turbine blades, they can produce a great amount of energy for their footprint size and weight. Their smaller footprint, low weight and multiple fuel applications make them the ideal power plant for offshore use.The rotation is used to drive other equipment, in a similar way as the steam turbine utilising the heat and pressure of the fuel as the driving energy. Hot exhaust gases can be used for steam generation, heat transfer, heating and cooling purposes.

© John Crane

2. Prime Movers – Water Turbines

The water turbine converts energy in the form of falling water into rotating shaft power. The amount of power which can be obtained depends upon the amount of water available i.e. the flow rate, and the head or fall through which it depends.

The rotating element (`runner') of a reaction turbine is fully immersed in water and is enclosed in a pressure casing. The runner blades are profiled so that pressure differences across them impose a lifting force (the wings on an aircraft), which cause the runner to rotate.

Francis Reaction Turbine Runner Typical Francis Reaction Turbine Typical Kaplan Reaction Turbine

© John Crane

An impulse turbine runner operates in air, driven by a jet (or jets) of water. Here the water remains at atmospheric pressure before and after making contact with the runner blades.In this case a nozzle converts the pressurised low velocity water into a high speed jet. The runner blades deflect the jet so as to maximise the change of momentum of the water and thus maximising the force on the blades.

Typical Pelton Wheel Turbines Typical Turgo ImpulseTurbine


© John Crane


This type of water turbine operates in a similar manner as a wind turbine but exploits underwater currents rather than air, based on the principle that all fluids behave the same way.

© John Crane

2. Prime Movers – Wind Turbines

A Wind turbine is a machine that converts kinetic energy from the wind into mechanical energy, and this energy can be used to produce electricity e.g. wind generators / farms, or used to drive other machinery to do useful work e.g. windmills.

© John Crane

2. Prime Movers – Internal Combustion Engines

Reciprocating or Hydraulic• Diesel / Gas Engines• Hydraulic Motors

A Reciprocating Engine, also often known as a piston engine, is a heat engine that

uses one or more reciprocating pistons to convert pressure into a rotating motion.

Diesel Engines

A Hydraulic Motor is a mechanical actuator that converts hydraulic pressure

and flow into torque and angular displacement (rotation).

© John Crane

2. Prime Movers – Electric Motors

Electric Motors• Direct on line (DOL)• Star Delta• Variable speed/variable

frequency

An Electric Motor converts electrical energy into mechanical energy. Most electric motors operate through interacting magnetic fields and current-carrying conductors to generate force.

Electric motors are commonly started Direct On Line (DOL) where the full line voltage is applied to the motor terminals. This is the simplest type of motor starter.

For Softer starts – Star Delta is preferred where the start is controlled in two phases'

Variable Speed/ Variable Frequency allows full control of the start up and operation.

Electric Motor

© John Crane

3. Rotating Equipment (Driven)– Centrifugal Pumps

Centrifugal• Pumps• Compressors• Mixers• Fans • Propellers

Centrifugal Driven machines are similar to a turbine but operating in reverse. Centrifugal force is defined as moving, or pulling away from a centre or axis.

Typically a Centrifugal Pump uses a rotating impeller to increase the pressure of a fluid.Centrifugal pumps are commonly used to move liquids through a piping system.The fluid enters the pump impeller along or near to the rotating axis and is accelerated by the impeller, flowing radially outward into volute chamber (casing), from where it exits into the downstream piping system.

Centrifugal Pump

© John Crane

3. Rotating Equipment (Driven)– Positive Displacement Pumps

Reciprocatingor Hydraulic

• Gear Pumps• Screw Pumps• Piston Pumps• Reciprocating Pumps

All Positive Displacement pumps deliver a constant amount of fluid for each revolution or stroke.

Gear Pumps use the meshing of gears to pump fluid by displacement. They are one of the most common types of pumps for hydraulic fluid power applications. Gear pumps are also widely used in chemical installations to pump fluid with a certain viscosity. Screw Pumps use one or several screws to move fluids or solids along the screw(s) axis. In its simplest form (the Archimedes' screw pump), a single screw rotates in a cylindrical cavity, thereby moving the material along the screw's spindle. A Piston Pump is where the high-pressure seal reciprocates with the piston. Piston pumps can be used to move liquids or compress gases.A Reciprocating Pump is a plunger pump. It is often used where relatively small quantity of liquid is to be handled and where delivery pressure is quite large.

Archimedes' screw pump

© John Crane

A centrifugal gas compressor is a mechanical devise that increases the pressure of a gas by reducing its volume.

As with a pump for liquids, a compressor increases the fluid pressure, and can transport the fluid through a pipe.

However, as gases are compressible, the compressor also reduces the gas volume whereas the main result of a pump is to increase the pressure of a liquid to allow it to be transported.

3. Rotating Equipment (Driven)– Compressors

© John Crane

Centrifugal Gas Compressor ConstructionComprises a casing containing rotating shaft, on which is mounted a cylindrical assembly of compressor blades.Each blade on the compressor produces apressure variation, similar to an aircraft propeller airfoil.Centrifugal compressors also do work on the flow by rotating (thus accelerating) the flow radially.

CC

==

RR

==


© John Crane

Centrifugal Gas Compressor Applications

They are used throughout industry because they:have few moving partsare very energy efficientgive higher airflow that a similarly sized reciprocating compressor


© John Crane

Refrigerant Compressors

Designed specifically for air conditioning, heat pumping and refrigeration applications. They are integral components of the refrigeration cycle, in which refrigerant gases are cyclically evaporated and condensed, absorbing heat from the load to be cooled, and delivering it to an open environment where it is dissipated.There are 3 main types of refrigerant compressors:ScrewPistonScroll


© John Crane

Agitators / Mixers / Reactors are machines for mixing or agitating a product within a pressure vessel. They are installed in process plants in industries such as chemical processing, pharmaceuticals, pulp and paper processing etc.

Applications include:blendingdissolvingheat transfersolids dispersionsolids suspensioncomplete chemical reactionspolymerisationcrystallisationneutralisation

3. Rotating Equipment (Driven)– Agitators / Mixers / Reactors

© John Crane

Most equipment can be classified into three types of configurations:

Top Entry – the mixer is mounted through an entry port at the top of the vessel.Bottom Entry – the mixer is mounted through an entry port at the bottom of thevessel.Side Entry – the mixer is normally mounted through a nozzle on the side of the vessel (normally mounted near the bottom of the vessel, to allow mixing at low liquid levels, and during filling and emptying).


© John Crane

Most agitators and mixers operate at low shaft speeds typically around 100 – 500 RPM. The deflection on a long overhung shaft will affect the design of the vessel and the sealing device. They will have to tolerate any run-out or misalignment due to shaft deflection.


© John Crane

Electrical An Electric Generator is a device that converts mechanical energy to electrical energy. The reverse conversion of electrical energy into mechanical energy is done by a motor; motors and generators have many similarities.

The source of mechanical energy may be a reciprocating or turbine steam engine, water falling through a turbine or waterwheel, an internal combustion engine, a wind turbine, a hand crank, compressed air or any other source of mechanical energy.

An Alternator is an electromechanical device that converts mechanical energy to electrical energy in the form of alternating current. Alternators in power stations driven by steam turbines are called Turbo-Alternators.

3. Rotating Equipment (Driven)– Electric Generators & Alternators

© John Crane

Industrial fans and blowers consist of shaft mounted rotor blades contained within a casing, and are used for creating a flow of gas (air).

Fans and blowers have diverse applications in many industries for the following typical processes:ExtractionVentilationCoolingAerationDrying etc.

Power Station Fly Ash BlowerTypical Industrial Fan

3. Rotating Equipment (Driven)– Fans & Blowers

© John Crane

4. Connectors – Modifiers and Couplings

Whenever two pieces of rotating machinery such as a pump and a motor need to be connected together, there is the possibility of a direct or indirect connection.

Equipment can be indirectly connected by belts or chains – for example think of a bicycle as the chain transfers pedal power to the wheel:

However indirectly coupled equipment is usually inefficient, due to frictional losses when the belts or chains slip during power transmission.

© John Crane

4. Connectors- Modifiers and Couplings

The alternative solution is a direct connection between the 2 machines:

Motor (Driver) Pump (Driven)

Prime Mover

(Driver)

Rotating Equipment

(Driven)Connector

© John Crane


ModifiersCouplings

With a Direct Drive between the driver and the driven equipment, some form of connector device is needed:

The types of driving and driven equipments being driven will affect the choice of the suitable connector device.There are various types of connector devices commonly in use in process industries.

Prime Mover

(Driver)

Rotating Equipment

(Driven)Connector

© John Crane


Modifiers are connectors and are so described as they ‘Modify’“ or ‘Change the input to output transmission properties such as:

Speed TorqueRotational Direction

Examples of Modifiers include:

Fluid couplingGearboxBeltsChains

© John Crane


Modifier

A Fluid Coupling is a hydrodynamic device used totransmit rotating mechanical power.

It also has widespread application in marine and industrial machine drives, where variable speed operation and/or controlled start-up without shock loading of the power transmission system is essential.

© John Crane


Modifier

A Transmission or Gearbox provides speed and torqueconversions from a rotating power source to another device using gear ratios.

© John Crane


Modifier

A Belt is a loop of flexible material used tolink two or more rotating shafts mechanically.

Belts may be used as a source of motion, to transmit power efficiently.

© John Crane


Modifier

A Chain Drive is a way of transmitting mechanical power.

By varying the diameter of the input and output sprockets with respect to each other, the gear ratio can be altered.

© John Crane


DiscGearGridChainDiaphragmElastomericRubber BlockUniversal JointRigidHosePin & Bush

All the above connectors transmit torque and speed without change to the drive characteristics seen with modifiers.Couplings can be used in conjunction with modifiers - they are not in direct competition.

The other types of connector devices are known as couplings:

© John Crane


A coupling is a device used to connect twoshafts together at their ends for the

purpose of transmitting torque.

© John Crane

Modifier Coupling

Universal JointGear BoxBelt Drive

ChainPin & BushChain DriveElastomeric

Fluid Coupling

Can you identify if the Connectors listed beloware Modifiers or Couplings?

Exercise

© John Crane

Pump types are generally classified according to how they transfer energy to the fluid, and the combination of pressure and flow which they are designed to generate:

• pumps which pass kinetic energy to the fluid by means of a rapidly rotating impeller are known as kinetic or dynamic or centrifugal pumps

• pumps in which the fluid is mechanically displaced are termed positive displacement pumps

Classification of pumps:

5. Further Rotating Equipment - Pumps

© John Crane

The Application Data Sheet will usually indicate the ‘Type’ of pump:


© John Crane


A pump data sheet or manufacturer’s rating plate should at least contain the following information:

• Manufacturer• Pump serial No• Pump Direction of Rotation• Duty Generated Head• Duty Flowrate• Pump Absorbed Power at Duty Point• Pump Running Speed• Pump Casing Design Pressure

© John Crane


The following data relevant to seal selection should also be included: • Shaft Size• Pumped Process Fluid (including temperature)• Barrier Fluid (including temperature)• Suction Pressure• Discharge Pressure• Chamber pressure• API Piping Plan

© John Crane

API 610 / ISO 13709 provides a code to classify the various types:

5. Centrifugal Pumps

© John Crane

5. Centrifugal Pumps – OH1

Centrifugal Pump- Horizontal, overhung,

flexibly coupled, foot-mounted (OH1)

Seal Chamber

Semi-open Impeller

© John Crane


Seal Chamber Pressure (OH1)Influenced by:

• Size of the impeller for a given shaft• Type of Seal Chamber

1. Traditional cylindrical with throat bushing2. Cylindrical with open throat3. Conical or Tapered bore

• Diameter of the seal chamber bore adjacent to back of the impellerThe radially smaller the back vane ‘sweep’ the lower its effectiveness

• The larger the bore diameter the higher the chamber pressure• The smaller the impeller size the higher the chamber pressure

Seal Chamber Pressure = Suction + K x (Differential Pressure) where K is a relative % value

K = 10% for Chamber type 1K = 10% to 30% for Chamber type 2 depending on impeller sizeK = <= 80% for Chamber type 3 depending on impeller size and bore diameter

adjacent to back of the impeller

© John Crane

Many single-stage pumps are known as back pull-out designs, because of the way that the bearing frame assembly is pulled out from the back of the pump volute:

5. Centrifugal Pumps

© John Crane


Typical OH2 Process PumpClosed impellerBalance holes

Image: Sulzer Pumps

Seal Chamber

Typical pumping applicationsfrom petroleum, petrochemical and gas processing industries

© John Crane

Image: Flowserve Pumps


Typical pumping applications includePetroleum, petrochemical andGas processing industries

© John Crane


Seal Chamber Pressure for OH2 pumpsStrongly influenced by the position of the balance hole in relation to the impeller bladeTypically holes in front of the bladeChamber pressure very close to Suction pressure conditions.Suggest the formula (Suction + 10% Differential Pressure) is usedBe careful!

• If within the blade curvature this can be below suction pressure.• Some ‘Circulator’ pumps have no rear wear rings or balance holes. These

pumps typically operate at significant suction pressures and the ‘head’ or differential pressure is low (2 to 3 bar). Seal chamber is at DP.

• Check if it is 2 stage. In ‘Pump language’, ‘Multistage’ means 3 stages or more!

© John Crane


Horizontal, overhung, flexibly coupled, centreline-mounted – OH2- 2-stage design

Sulzer Ahlstom APP

Seal chamber pressure =

1st Stage DP + (10% 2nd Stage Differential Pressure)

Typical pumping applications include pulp & paper and general applications.

© John Crane


Overhung, Vertical, In-Line, bearing frame Pump (OH3)

Sulzer OHV Pump

Typical pumping applications include refineries, oil & gas production, pipeline boosting and offshore applications.

© John Crane


Seal Chamber Pressure as for OH2Often fitted with Plan 13 which may reduce the pressure even closer to Suction pressureBe careful of 2 stage designs

© John Crane


Overhung, Vertical, In-Line, Rigidly Coupled Pump (OH4)- Not commonly used

Flowserve OH4 PumpDouble Suction impeller

Typical pumping applications includeflammable liquids, fuel, petroleum, petrochemicals,light oils, hydrocarbonbooster, water and general applications.

© John Crane


Overhung, In-Line, Vertical, Close-coupled Pump (OH5)

A Shell preference DEP pump

© John Crane


Overhung, In-Line, Vertical, Close-coupled Pump (OH5)Seal Chamber Pressure as for OH2Often fitted with Plan 13 which may reduce the pressure even closer to Suction pressureBe careful of 2 stage designs!

Flowserve OH5 Pump

Seal Chamber Pressure

= Suction + (50% Differential Pressure)

© John Crane

Multistage pumps - a ‘between bearings’ configuration:

A multistage pump is an example of a between bearings design, where the shaft and impellers are supported on 2 sets of bearings, one at either end of the pump:

This is in contrast to an overhung design commonly used on many single-stage pumps, where the shaft and impeller are supported on only one side, and overhang as a cantilever. However with multiple impellers a shaft support is needed at both ends.The 2 ends of a multistage pump are generally referred to as the drive end DE (i.e. the motor & coupling end of the shaft) and the non-drive end NDE respectively.

bearings multiple impellers

shaft supports (bearings)

5. Centrifugal Pumps - Multistage

© John Crane

Horizontal split casing pumps:Horizontal split casing pumps are versatile designs, found in a wide variety of applications such as:

• water supply schemes• irrigation• industrial water supply• oil refineries• chemical and fertilizer plants• electricity boards• mining etc.

5. Centrifugal Pumps – Horizontally Split

© John Crane

Horizontal split casing pumps:

large axially split pumps used on a hydropower project

(India)

hot water circulation pumps in a district heating system

(China)

Examples of industrial applications for horizontal split casing pumps include:

5. Centrifugal Pumps – Horizontally Split

© John Crane

Between Bearing, single stage, axially split (BB1) PumpNearly always supplied with a double suction (low NPSH with high Q)

Seal ChamberSeal Chamber

Seal chamber pressure = Suction

pressure

Flowserve BB1 single stage Pump

5. Centrifugal Pumps – Axially Split BB1

© John Crane

Between Bearing, 2 stage, axially split (BB1) Pump

Flowserve BB1 2 stage Pump

Chamber Balance Line

Seal Chamber

Seal Chamber


© John Crane

Seal Chamber Pressure (2-stage BB1)

Seal chamber on Suction end (Drive End) = Suction Pressure

Seal chamber on Non-Drive end = Suction + (50% Differential Pressure)?

Is a ‘balance line’ connected from the NDE Chamber back to the suction pressure? If so both ends = Suction Pressure

Not always done on a 2 stage pump, particularly those without a double suction inlet impeller (already balanced axial thrust)!

The existence of a ‘balance line’ is NOT clear from the Pump Data Sheet

Recommend always assume NO balance line fitted. i.e.

Seal chamber on Second stage end = Suction + (50% Differential Pressure)

5. Centrifugal Pumps – BB1

© John Crane

Reducing axial thrust across the pump:

Balance line:Another way of equalising pressure and balancing axial loading across the pump casing is to use a balance line. This type of design is also used in multi-stage pumps.The balance line consists of an external pipe, connecting the high (discharge) side of the pump back to the low (suction) side.

balance line

5. Centrifugal Pumps – Balance Lines

© John Crane

Between Bearing, single stage, radially split (BB2) PumpNearly always supplied with a double suction

Seal Chamber

Seal Chamber

Sulzer BB2 Pump

Seal chamber pressure = Suction pressure

5. Centrifugal Pumps – Radially Split BB2

Typical pumping applications include hydrocarbon processing.

© John Crane

Between Bearing, 2 stage, radially split (BB2) Pump

Balance Line

Seal chamber pressure = Suction pressure

Sulzer BB2 2 stage pump


© John Crane

Between Bearing, 2 stage, radially split (BB2) PumpFace to Face impellersAxial Force balancedNo rear wear rings or balance holesBalance Line?Seal Chamber Pressure?Be very careful of BB1 & BB2 seal chamber pressure predictions


Typical pumping applications include heavy oil, boiler feed, oil / shale sands, hydraulic press (metal), hydrocracking, hydrotreating, acid transfer, industrial gases, catalytic cracking, caustic and chor-alkali.


© John Crane

Multistage, axially split Pumps (BB3)4 stage back-to-back impellers

Sulzer BB3 Pump

Diffuser

Seal Chamber


Typical pumping applicationsinclude refineries, petro-chemicals, pipelines, waterinjection and power generationapplications.

© John Crane

Multistage, axially split Pumps (BB3)9 stage ‘opposed’ or ‘back-to-back’ impellersSeal chamber pressure = Suction pressure on both ends

Sulzer BB3 Pump Balance Line

SuctionDischarge


© John Crane

Radially split / stage casing pumps:Some pump designs have the pump body radially split (vertically split) into individual stages. Each stage is fitted with a diffuser guiding the flow into the next stage, thereby increasing the pressure by the head generated in each individual impeller.These designs are sometimes also known as stage casing pumps.Pumps of this design normally have a very robust construction, for use on high pressure services. The pump casings are held together by tie-bolts, and all impellers are dynamically balanced.

tie-bolts

5. Centrifugal Pumps – Radially Split

Typical pumping applications includewater booster pumps, boiler feed pumps and building services

© John Crane

Multistage, radially split Pumps, single casing (BB4)

Sometimes called ‘Ring Section’ or ‘Segmental Ring’ PumpsNon preferred by API 610/ISO 13709Seal Chamber pressure = Suction pressure if balance drum used to manage shaft axial thrustBe careful if design uses a balance disc to manage shaft axial thrust

• Suction end seal chamber = Suction pressure• Other end seal chamber = Suction pressure + ?% Differential Pressure


© John Crane


Balance Drum

Seal chamber pressure (NDE & DE) = Suctionpressure


Typical pumping applicationsinclude desalination,descaling, water supply /distribution, crude, productand CO2 pipelines, ground-water development /distribution, irrigation and water treatment.


© John Crane



Balance Disc

Seal chamber pressure (DE) = Suction pressureSeal chamber pressure (NDE) = Suction pressure + ?%Pressure

Typical pumping applicationsinclude water supply / distribution, desalination, mining dewatering / supply, groundwater developmentand irrigation applications.


© John Crane

Multistage, radially split Pumps, double casing (BB5)Sometimes referred to as, ‘Barrel Casing’ PumpsEliminates the potential leak path between each stage segment

Balance Drum

Sulzer BB5 Pump

Typical pumping applicationsinclude oil production, refining,and boiler feed applications.


© John Crane

Shaft axial thrust imbalance designs as for single casing BB4 pumpsNote the Pump Data Sheet rarely indicates the use of a throat bushing, balance drum or discNormally suction inlet on DE & Seal Chamber pressure = Suction pressureNDE Seal Chamber pressure with balance drum = Suction pressureNDE Seal Chamber pressure with balance disc = Suction pressure + ?%Differential PressureWear of drum and disc increases NDE Seal Chamber pressure; discuss with OEM the tolerance range.

• Applies to both BB4 and BB5. Weir FK BB5 Pump

Multistage, radially split Pumps, double casing (BB5)

Typical pumping applications include sea water injection,produced water injection, main oil lines, condensateexport, boiler feed, power plant and refinery applications.


© John Crane

Vertically Suspended, Single Casing, Column DischargeDiffuser design (VS1)‘Wet Pit’ Pump

Flowserve VS1 Pump

5. Centrifugal Pumps– Vertically Suspended VS1

© John Crane

Vertically Suspended, Single Casing, Column Discharge- Diffuser design (VS1)

Seal Chamber pressure = Dischargepressure

Flowserve VS1 Pumps

Typical pumping applications include chemical / petrochemical, liquefied gas pipeline / transfer service, offshore crude oil loading, lubricating oil, condensate extraction, seawater lift,stormwater / drainwaterservices, recovered oil, and tank services.


© John Crane

Vertically Suspended, Single Casing, Column discharge- Volute design (VS2)

Limited number of stagesSeal Chamber pressure = Discharge pressure

Flowserve VS2 Pump

Typical pumping applications include raw water intake,freshwater supply / distribution, irrigation, fire protection,condensate extraction, heater drainage, transfer, loadingand unloading, steel mill cooling and quench services, mine dewatering and acid leaching, brine recirculation and MSF desalination blowdown.


© John Crane

Vertically Suspended, Single Casing, Column discharge- Axial Flow design (VS3)

Limited number of stagesSeal Chamber pressure = Discharge pressure

Flowserve VS3 Pump

Typical pumping applications include water treatment, agriculture, power plant cooling water, mine dewatering and supply and groundwater, development / irrigation.


© John Crane

Vertically Suspended, Single Casing, Sump discharge- VS4 & VS5

Liquid level in column same us sumpSeal Chamber in air or inert gas in sumpSeal Chamber at Atmospheric pressure

Typical pumping applications include flood control, groundwater development/irrigation, water supply/treatment for oil and gas, molten salt transfer, waste water treatment, heavy oil and oil sands and shale.

5. Centrifugal Pumps– Vertically Suspended VS4 & VS5

© John Crane

Vertically Suspended, Double Casing Pump- Diffuser design (VS6)

Low margin from VP at Suction (low NPSHA)Small footprint

Balance Chamber

Seal Chamber

Balance Drum

Typical pumping applications include hydrocarbon booster, transfer pipeline booster, chemical / petrochemical transfer, condensate, brine injection, crude oil loading, condensate extraction and cryogenic services.


© John Crane

Vertically Suspended, Double Casing Pump- Diffuser design (VS6)

Shaft in Discharge LineBe careful estimating Seal Chamber pressure!Seal chamber at Discharge Pressure (Plan13)

Or alternatively:• ‘Leak-off’ design from throat bushing to

lower Seal Chamber pressure• Balance drum design• Seal Chamber at Suction pressure• Plan 11 or 14

No clarity of design in Pump Data Sheet

Typical pumping applications include cryogenic applications handling such chemicals as ammonia, ethylene, propylene, LPG / LNG, methane and butane.


© John Crane

Positive Displacement Pumps

Gear Pump

Internal Gear

External Gear

Screw Pump

Screw Pump

Archimedian Screw Pump

Progressing Cavity Pump

Vane Pump

Flexible Vane Pump

Sliding Vane Pump

Liquid Ring Pump

Lobe Pump

Rotary Non-RotarySealless rotary PD

Pump designs

6. Positive Displacement Pumps

Classifications of positive displacement pumps include:

© John Crane

Seal Chamber Pressure in Rotary Positive Displacement Pumps:

Evaluate the pressure conditions at the process entrance to the Seal ChamberIs there a process flush to the seal (Plan 01, 11, 12, 14, 21, 22, 31, 32, 41)?Is there a process flow from the seal chamber (Plan 13, 14)?Is this flow liable to affect the seal chamber pressure?


© John Crane

A positive displacement pump has a cavity or cavities which are alternately filled and emptied by the pump action, causing fluid to move in a forward-only fashion. There is an expanding cavity on the suction side of the pump, and a decreasing cavity on the discharge side.Liquid is allowed to flow into the pump as the cavity on the suction side expands, and the liquid is then forced out of the discharge as the cavity collapses.

Positive displacement pumps all operate on similar working principles, but are generally classified into reciprocating and rotary designs. Types of positive displacement pump design include:

• rotary lobe• gear within a gear• reciprocating piston• screw• progressive cavity etc.

Unlike a centrifugal pump, a positive displacement pump will produce the same flow at a given speed, no matter what the discharge pressure is.


© John Crane

Rotary Positive displacement pump: Archimedian Screw Pump

Seal Chamber – atmospheric air• Seal required?

Image: math.nyu.edu

SeaWorld Adventure Park (San Diego, CA)

Typical pumping applications include raw and treated sewage effluent, land drainage and irrigation.


© John Crane

Rotary Positive displacement pump: Progressing Cavity Screw Pump

Mono Compact C

Seal Chamber

Seal Chamber = Suction Pressure• Can be Discharge Pressure if run

backwards!

Typical pumping applications include high viscosity lotions / pastes and sewage sludge etc.


© John Crane

Rotary Positive displacement pump: Screw Pump

Seal Chamber – Suction PressureWarren Imo Screw Pump

Typical pumping applications include lubrication oils and clean products.


© John Crane

Rotary Positive displacement pump: Internal Gear Pump

Albany HD Gear Pump

Seal Chamber= [Suction Pressure + (Differential

Pressure/2)]??

Typical pumping applications include lubrication oils and clean products.


© John Crane

Rotary Positive displacement pump: External Gear Pump

Seal Chamber

Seal Chamber– [Suction Pressure + (Differential

Pressure/2)]??Image: Viking Pump Inc


© John Crane

Rotary Positive displacement pump: Lobe Pump

OutletOutletInletInlet

Seal Chamber (2 off)

Typical pumping applications includehygienic materials, food productionand pharmaceutical applications


© John Crane

Seal

Seal Chamber

Seal Chamber Pressure= [Suction Pressure + (80%

Differential Pressure)]• Careful of pulsations!


Rotary Positive displacement pump: Lobe Pump

© John Crane

Rotary Positive displacement pump– Flexible & Sliding Vane Pump

Image: Viking Pump Inc

Clarksol Flexible Vane Pump

Seal Chamber– [Suction Pressure +

(Differential Pressure/2)]??

Image: Blackmer Sliding Vane PumpSeal Chamber

Typical pumping applications include liquids with poor lubricating qualities and food handling applications


© John Crane

Liquid for liquid ring (normally water) continually injected into the impeller cavity and the seal chamber (Plan 32)Injection pressure usually known but sourced from discharge separatorAssume seal chamber is discharge pressureStatically the chamber may be full vacuum

Typical pumping applications include forming pulp & paper products, e.g. egg boxes / packaging, petroleum refining, e.g. vacuum distillation.


Rotary Positive displacement pump: Liquid Ring Vacuum Pumps

© John Crane

True FalseFluid is mechanically displaced in a Kinetic or dynamic pump?An impeller will impart kinetic energy to a fluid?Centrifugal pump types are classified in API 610/ISO 13709?Impellers can be classed as open, semi-open and closed?A sliding vane pump is a type of dynamic pump?Progressing cavity pumps can be run in reverse?A screw pump is ideal for pumping raw sewage?A positive displacement pump will produce the same flow at a given speed, no matter what the discharge pressure is?

Can you answer the questions below?

Exercise

© John Crane

There is a huge range of rotating equipment used in process industries,e.g. pumps, compressors, turbines, mixers and fans etc.

Rotating equipment operates in different ways to do work to a liquid or gas, transferring energy from the driving to the driven machine

The equipment data sheet will identify the equipment type and its design / operating criteria

The equipment data sheet can also be used to aid seal selection

For effective and reliable performance the sealing solution must integrate with the equipment design

7. Summary / Conclusion

© John Crane

Further Information

Further learning on this topic can be found in the relevant Know-How curriculum:

Pump Principles

overview of rotating equipment.pdf

Documents