Compressor and Pump Curves
-
Upload
syed-muzamil-ahmed -
Category
Documents
-
view
226 -
download
0
Transcript of Compressor and Pump Curves
-
7/21/2019 Compressor and Pump Curves
1/14
Compressor and Pump Curves 1
1
Compressor and Pump Curves
1999 - AEA Technology plc - All Rights Reserved.
ADV 1_2.pdf
-
7/21/2019 Compressor and Pump Curves
2/14
2 Compressor and Pump Curves
2
WorkshopIn this module, compressor and pump curves will be used to model the
behaviour of simulated compressors and pumps. Using curves to
model these unit operations allows HYSYS to accurately simulate actual
plant equipment.
Learning ObjectivesOnce you have completed this module, you will be able to:
Specify and attach head and efficiency curves to compressors
Use single and multiple curves to model compressors
Attach head curves to pumps
Accurately model existing plant equipment with HYSYS
PrerequisitesBefore beginning this module, you need to know how to:
Define and import a fluid package
Add streams and unit operations to the PFD
-
7/21/2019 Compressor and Pump Curves
3/14
Compressor and Pump Curves 3
3
Compressor CurvesUsing compressor curves in your HYSYS simulation allows you to
accurately model existing plant equipment. You can determine if an
existing compressor is able to meet the specifications of your process.
Using compressor curves allows HYSYS to calculate heads and
efficiencies that are dependant on the flow rate. If the flow rate through
the compressor is known to be constant, a single flow rate and
efficiency can be supplied. If, however, the flow rate is expected to
change, using a compressor curve will allow HYSYS to calculate new
heads and efficiencies based on the current flow rate.
This results in greater accuracy in the simulation, and allows HYSYS to
more closely model actual plant equipment.
Defining the Fluid Package
Before we begin any simulation in HYSYS, we must first define the
appropriate fluid package.
1. Start a New Case and add a Fluid Package.
2. Select the Sour PREOS package
3. Add the following components: H2O, H2S, CO2, C1, C2, C3, i-C4,and n-C4.
-
7/21/2019 Compressor and Pump Curves
4/14
4 Compressor and Pump Curves
4
Installing a Stream1. Add a Material Steam to the PFD with the following data:
In This Cell... Enter...
Name Feed
Temperature 70 oC (160 oF)
Pressure 130 kPa (19 psia)
Molar Flow 500 kgmole/hr (1100 lbmole/hr)
Mole Fraction [H2O] 0.24
Mole Fraction [H2S] 0.07
Mole Fraction [CO2] 0.06
Mole Fraction [C1] 0.04
Mole Fraction [C2] 0.11
Mole Fraction [C3] 0.25
Mole Fraction [i-C4] 0.08
Mole Fraction [n-C4] 0.15
-
7/21/2019 Compressor and Pump Curves
5/14
Compressor and Pump Curves 5
5
Adding the Compressor1. Add a Compressorto the PFD.
2. Enter the following information on the Connectionspage:
3. On the Parameterspage, ensure that the Polytropic and Adiabaticefficiency boxes both read .
These values must read because the efficiencies will be
calculated from the compressor curves, and defining the same value in
two places will alwaysresult in a consistency error.
In This Cell... Enter...
Inlet Stream Feed
Outlet Stream Outlet
Energy Stream Comp Duty
Compressor button
-
7/21/2019 Compressor and Pump Curves
6/14
6 Compressor and Pump Curves
6
4. On the Curvepage, select theAdiabaticradio button in theEfficiencygroup. Press theAdd Curvebutton, and enter the dataas shown here:
5. Close the above view and activate Curve-1 on the Curvespage.Ensure that the Enable Curves box on the Curves page ischecked.
Be sure to use the correct unitsfor the curve.
We do not need to enter acompressor speed because weare only entering one curve.However, multiple curves withdifferent speeds can be used.
-
7/21/2019 Compressor and Pump Curves
7/14
Compressor and Pump Curves 7
7
6. The pressure of the outlet stream can be seen on theWork Sheetpage, or you can choose Show Tablewhen object-inspecting theoutlet stream on the PFD. The compressors efficiencies can befound on the Resultspage.
Optional ExerciseIt is desired to have an outlet pressure of300 kPa (44 psia).
Use an Adjust operation with the following information:
What is the Outlet Pressure of the compressor? __________
What is the Adiabatic Efficiency? __________
The Polytropic Efficiency?___________
In This Cell... Enter...
Adjusted Variable Feed - Molar Flow
Target Variable Outlet - Pressure
Specified Target Value 300 kPa (44 psia)
Step Size 5 kgmole/hr (10 lbmole/hr)
Iterations 50
What is the Molar Flow rate if the Outlet Pressure is set at300 kPa (44 psia)? __________
Can you think of an easier way of doing this? __________
How? __________
Save your case!
-
7/21/2019 Compressor and Pump Curves
8/14
8 Compressor and Pump Curves
8
Multiple CurvesTypically, industrial compressors are able to run at multiple speeds
depending on the current demand. HYSYS allows users to enter
multiple compressor curves that each represent a specified speed.
Once the curves are entered, any compressor speed can be specified
and the head and efficiency are calculated automatically.
In this exercise, a Natural Gas compressor will be examined to
determine the outlet pressure of a multi-speed compressor.
1. Begin a new case and import the fluid package Nat-Gas.fpkfrom
the diskette provide with this course.
2. Add a new stream to the PFD with the following data:
3. Add a Compressorto the PFD with this data:
4. Delete the default Adiabatic Efficiency value on theParameterspage. Again, the efficiency will be calculated from the compressorcurves.
In This Cell... Enter...
Name LP Gas
Temperature 10 oC (50 oF)
Pressure 1700 kPa (245 psia)
Molar Flow Rate 1500 kgmole/hr (3300 lbmole/hr)
Comp. Mole Fraction - C1 0.99
Comp. Mole Fraction - C2 0.002
Comp. Mole Fraction - C3 0.0005
Comp. Mole Fraction - N2 0.005
Comp. Mole Fraction - CO2 0.0025
In This Cell... Enter...
Inlet LP Gas
Outlet HP Gas
Energy Comp Duty
-
7/21/2019 Compressor and Pump Curves
9/14
Compressor and Pump Curves 9
9
5. Add the four curves shown below to the compressor. Note thatthe curves have been supplied in Field units. (If you are using SIunits, you must change the Flow and Head units to those shownhere beforeyou enter the curve data).
Note that compressor speedsmust be entered here asmultiple curves are beingused.
-
7/21/2019 Compressor and Pump Curves
10/14
10 Compressor and Pump Curves
10
The plots for efficiency andhead versus flow can be seenby pressing the Plot Curvesbutton on the Curvespage.
-
7/21/2019 Compressor and Pump Curves
11/14
Compressor and Pump Curves 11
11
6. Ensure that all of the curves are activated, and the Enable Curvesbox is checked. These curves are polytropic curves, therefore thePolytropicradio button must be checked in the Efficiencygroupon the Curves page.
7. On the Curvespage, enter a speed of 11 000 per min.
Optional Exercise
1. Delete the specified compressor speed of 11 000 per minute.
2. Enter a pressure of 5000 kPa (725 psia)for the HP Gasstream.
3. HYSYS will automatically calculate the compressor speed neededto meet this outlet pressure.
What is the pressure of the HP Gas stream? __________
What is the compressor speed needed to achieve thespecified outlet pressure? __________
What are the Adiabatic and Polytropic efficiencies of thecompressor under these conditions? __________
What is the temperature of the HP Gas? __________
Instead of entering all of thecurve data, open the HYSYScase Comp_Shortcut.hsconthe disk supplied with thismodule, and begin on step 6.
Save your case!
-
7/21/2019 Compressor and Pump Curves
12/14
12 Compressor and Pump Curves
12
Pump CurvesAs with compressor curves, pump curves are used to allow HYSYS to
accurately model existing pumps. Pump curves allow the pressure rise
across the pump to be dependent on the flow rate of liquid.
The pump curves are entered into HYSYS using a form different than
the form used for compressor curves. With pump curves the
coefficients of an expression, up to the fifth order, are entered into
HYSYS rather than the actual data points.
Defining the Fluid Package
1. Begin a new case and select the Peng RobinsonEOS package.
2. Add the components n-Hexane, n-Heptane, andn-Octane.
Installing a Stream
Add a new stream to the PFD and enter the following information:
The coefficients can beobtained from a spreadsheetprogram capable of nonlinearregression, such as EXCEL, or
may be supplied by the pumpsmanufacturer.
In This Cell... Enter...
Name LP Mixture
Temperature 25 oC (77 oF)
Pressure 120 kPa (18 psia)
Liquid Volume Flow 500 m3/hr (76,000 BPD)
Comp. Mass Fraction [Hexane] 0.60
Comp. Mass Fraction [Heptane] 0.30
Comp. Mass Fraction [Octane] 0.10
-
7/21/2019 Compressor and Pump Curves
13/14
Compressor and Pump Curves 13
13
Adding the Pump1. Add aPumpto the PFD and enter the following information:
2. On the Curvespage, enter the following data:
In This Cell... Enter...
Inlet LP Mixture
Outlet HP Mixture
Energy Pump Duty
Efficiency (ParametersPage) 75 %
Pump button
In This Cell... Enter...
Coefficient A 3000
Coefficient B -2.0
Coefficient C -0.005
All Other Coefficients 0
Units for Head m
Flow Basis Act. Vol. Flow
Units for Flow m3/hr
-
7/21/2019 Compressor and Pump Curves
14/14
14 Compressor and Pump Curves
14
3. Ensure that theActivate Curvesbox is checked.
4. The pressure of the product stream can be seen on theWorksheettab.
What is the outlet pressure of the pump? __________
The pump sales representative, who supplied the curvedata, guaranteed an outlet pressure of 5000 kPa (725 psia)at the specified flow rate. Should you fill out the purchaseorder? __________
Save your case!