Centrifugaal Pompen Versie 2015 (Armfield)

Thema 5 CT

Procestechnologie

MODULE

Centrifugaal pompen (Armfield)

Versie 15-06-15

Inhoudsopgave

1 Centrifugal Pump(s)......................................................................................31.1 Equipment: Armfield Pumps Instruction Manual......................................31.2 Description..............................................................................................31.3 Instructional Capabilities Reference Manual.........................................31.4 Literature.................................................................................................41.5 Theory.....................................................................................................41.6 Practical Training Exercises.....................................................................5

FM21 1 Using engineering units: wordt niet uitgevoerd...........................5FM21 2 Pump inherent characteristics....................................................5FM21 3 Pump constant speed characteristics.........................................6FM21 4 Introduction to scaling: use results of experiment no. 3..............6FM21 5 Pump suction: wordt niet uitgevoerd..........................................6FM21 6 System characteristic-duty point................................................7FM21 7 Series pumps operation: wordt niet uitgevoerd...........................7FM21 8 Parallel pumps operation...........................................................7

Pompen, Practicumhandleiding, Thema 5 CT Procestechnologie 1

1 Centrifugal Pump(s)

The centrifugal pump is the machine most commonly used to move liquids from one place to another. As such, the Armfield FM21 demonstration unit is particularly instructive to the subject of rotodynamic fluid machines. Discovering the relationship between head, flow, rotational speed and power, provides a framework of general applicability.Centrifugal pumps are often used together to enhance either the flow rate or the delivery pressure beyond that available from a single pump. The unit is designed to demonstrate the operational advantages of parallel or serie operation, depending on the required duty.

1.1 Equipment: Armfield Pumps Instruction Manual- Series and Parallel Pumps Unit FM21- Two SWA1 Integrating Wattmeters- IFD4 Interface Console IFD4- PC with Windows Software

1.2 Description

The bench-top unit is self-contained and includes a reservoir and pipework for continuous water circulation. Ball valves at the pump inlets and outlets allow the configuration to be selected. A manually operated valve controls the flow, which is monitored by a single orifice plate. The maximum head of each of the motor driven two single-stagepumps is 10 mWG, and maximum flow (each pump) is 1 litre/s.Measurements sensors are included in the supply. They monitor:- pressure head across each of the pump;- ΔP across the orifice plate (hence flow rate);- water temperature at the inlet;- rotational speed of the impellers.

1.3 Instructional Capabilities Reference Manual

- Demonstration of either series, parallel FM21 or single pump operation;- Comparison of head-flow characteristics with single

pump operation;- Comparative measurement of power and overall efficiency at different speeds.


1.4 Literature

1. A. Nouwen, Pompen, 4e druk, Educaboek (2002).

1.5 Theory

Consult the instruction manual and the literature.

keywords: discharge (flow rate or capacity) Φv;head (ned.: opvoerhoogte);discharge pressure;power input and efficiencies;pump speed N [rpm of Hz]]centrifugal pump operating characteristics:- discharge pressure or head against Φv curve- overall efficiency against Φv curve- electrical power of pump against Φv curve; cavitation and `net positive suction head' (NPSH);dimensionless head-discarge characteristic of a centrifugal pump;head-discharge curves for a pumping installation;operating characteristics of two pumps running in a series and in a parallel pumping installation;


1.6 Practical Training Exercises

In dit hoofdstuk worden de uit te voeren onderdelen kort behandeld. Voor een uitvoerige beschrijving van deze experimenten (achtergrond, benodigde handelingen etc) zie Instruction Manual Armfield FM21.

FM21 1 Using engineering units: wordt niet uitgevoerd

The objective of this exercise is to ensure that users fully understand the conversion of measured units of quantity to those of the variables necessary to calculate pump performance.

FM21 2 Pump inherent characteristics

The objective is to obtain a head-flow curve for centrifugal pump operating at inherent speed. The best way to describe the operating characteristics of an centrifugal pump is through the use of characteristic curves showing the interrelation of discharge pressure or head H, capacity Φv and efficiency Egr , and power input Pgr for a given pump at inherent speed (maximum power).

Let op: Wat doet het toerental. Geef ook dit aan in het logboek.

Maak een figuur zoals onderstaand weergegeven (zie ook Instruction Manual Armfield FM21). In Excel vraagt het weergeven van de Pump Efficiency en Power input twee aparte grafieken.


FM21 3 Pump constant speed characteristics

To obtain the head-flow curves for a centrifugal pump at a range of pump speeds, and to relate these parameters to pump efficiency, the procedure of exercise 2 is repeated with relatively low pump speeds e.g. 30 ,35, 40, 45 Hz (note: check feasibility of these speeds).

FM21 4 Introduction to scaling: use results of experiment no. 3

It is not practical to test the performance of every size of pump in a manufacturer’s range at all speeds at which it may be designed to run. Hence a mathematical solution is required whereby assumptions can be made as to the operating characteristics of a pump running at one speed, impeller size, etc., from experimental results taken at another.

The objective is to predict the head-flow characteristic at one pump speed fromthose measured at another speed.

Note:As indicated, there is no need to perform test runs to gain all pumpcharacteristics. Instead, one set of results of Experiment 3 is used to predict the other ones as they are to test the ‘scaling laws’ (zie [1] en Instruction Manual Armfield FM21).

Doel: Laat zien dat de opschalingregels van toepassing zijn voor de pompcurves verkregen bij de verschillende toerentallen (experiment 3). Neem hierbij één basis toerental en vertaal deze naar de curven voor de andere toerentallen. Vergelijk experimenteel en model.

FM21 5 Pump suction: wordt niet uitgevoerd

In both the design and operation of a rotodynamic machine, careful attention has to be paid to the fluid conditions on the suction side. In particular, it is important to check the minimum pressure that can arise at any point to ensure that cavitation does not place.

In this exercise the effect on pump performance of different suction conditions at the pump inlet is investigated.Warning:Continue the restriction of the inlet, taking data samples at the same constant speed, until the pump no longer draws any water from the feed tank. Then stop the pump operation immediately to prevent damage.


FM21 6 System characteristic-duty point

System analysis for a pumping installation is conducted to select the most suitable pumping units and to define their operating points (or duty points, Dutch: werkpunt). The operating point is found by plotting the pump head-discharge curve with system head-discharge curve. The intersection of these curves represents the head and the discharge that the pump will produce if operated in the given piping system. The system (valves, pipes, fittings etc.) – head curve is obtained by measuring the head against which the fluid must be pumped relative to atmospheric pressure. Zie ook Instruction Manual Armfield FM21 pagina PE6-2 en raadpleeg vooraf de docentDuring measurement the outlet discharge valve is partly closed forming a significant resistance to flow.

FM21 7 Series pumps operation: wordt niet uitgevoerd

Should the head of a single pump not be sufficient for an application, pumps can be combined in series to obtain an increase in head. The objective of this exercise is to demonstrate the operating characteristics of two pumps in a running series pumping installation.

FM21 8 Parallel pumps operation

Should the flow of a single pump not be sufficient for an application, pumps can be combined in parallel configuration to obtain an increase in flow. The objective of this exercise is to demonstrate the operating characteristics of two pumps in a running parallel pumping installation.Let op: Selecteer in de software Parallel Pumps Operation.


Centrifugaal Pompen Versie 2015 (Armfield)

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