Reciprocating Compressor - Cylinder/Equivalent Capability & Horsepower

This application uses a positive displacement compressor model to deliver gases at high pressures. With piston displacement reciprocating compressors, often final outlet temp could be a concern.
 
Piston Displacement
Single-Acting Piston Compression on the Outer End Only:
PTLB Compressors 2.5 Intro.png
 
Single-Acting Piston Compression on the Crank End Only:
PTLB Compressors 2.5 Intro 2.png
 
Double-Acting Piston Compression (Other than Tail Rod Type):
PTLB Compressors 2.5 Intro 3.png
 
Double-Acting Piston Compression (With a Tail Rod):
PTLB Compressors 2.5 Intro 4.png
𝑃𝐷 − Piston Displacement[ft3/min]
𝑠 – Stroke[𝑖𝑛]
𝑛 − Rotational Speed[rpm]
𝐷 − Cylinder Inside Diameter[in]
𝑑 − Piston Rod Diameter [in]
 
 
Reciprocating Compressor Volumetric Efficiency 
PTLB Compressors 2.5 Intro 5.png
𝑉𝐸−Volumetric Efficiency[%]
𝐴 − Effect of Leakage, Losses, etc.[%]
𝐿𝑢 − Effect due to Lack of Lubrication[%]
𝑟 − Compression Ratio[𝑃2/𝑃1]
𝐶−Cylinder Clearance as a Percent of Cylinder Volume[%]
𝑧𝑠 − Compressibility Factor at Suction Conditions
𝑧𝑑 − Compressibility Factor at Discharge Conditions
𝑘 − Adiabatic/Isentropic Exponent[𝑐𝑝/𝑐𝑣]
 
 
In practice for normal operation
PTLB Compressors 2.5 Intro 6.png
 
 
CNGA/GPSA Compressibility Factor Approximation
PTLB Compressors 2.2_Intro 2.png
𝑍 − Compressibility Factor
𝑃 − Pressure(psi)
𝑇𝑓 − Gas Flowing Temperature[°𝑅]
This approximation will produce results sufficiently accurate for preliminary calculations.
 
PTLB Compressors 2.5 Intro 7.png
 
 
Reciprocating Compressor Horsepower
PTLB Compressors 2.5 Intro 8.png
𝑄 − Suction Capacity[SCFM]
𝑃1 − Gas Suction Pressure(psi)
𝑛 − Compressor Efficiency
𝑘 = PTLB Compressors K Formula.png −Specific Heat Ratio
𝑟 − Compression Ratio [𝑃2/𝑃1]
 
 
 
Ideal Discharge Temperature
PTLB Compressors 2.5 Intro 9.png
𝑇2(𝑖𝑑𝑒𝑎𝑙− Ideal Discharge Temperature[°R]
𝑇− Suction Temperature[°R]
𝑟 − Compression Ratio [P2/P1]
𝑘 − 𝐴diabatic/Isentropic Exponent PTLB Compressors 2.5 Intro 10.png
 
 
Theoretical Discharge Temperature
PTLB Compressors 2.5 Intro 11.png
𝑇2 = 𝑇1 + ∆𝑇𝑖𝑑𝑒𝑎𝑙
𝑇2 − Theoretical Discharge Temperature[°R]
 
 
 
Actual Discharge Temperature
PTLB Compressors 2.5 Intro 12.png
𝑇= 𝑇1 + ∆𝑇𝑎𝑐𝑡𝑢𝑎𝑙
𝑇2 − Actual Discharge Temperature[°R]
𝑛𝑎 − Adiabatic (Isentropic)Efficiency

 

 

Input Parameters

  1. To create a new case, click the “Add Case” button
  2. Select the Reciprocating Compressor – Cylinder/Equivalent Capability & Horsepower application from the Pipeline Compressor module.
  3. Enter Case Name, Location, Date and any necessary notes.
  4. Fill out all required fields.
  5. Make sure the values you are inputting are in the correct units.
  6. Click the CALCULATE button.

 

  • Base Pressure(psi)
  • Base Temperature(°F)
  • Select Piston Acting Compressor Type
  • Bore/Cylinder Inside Diameter(in)
  • Stroke/Travel Length of Piston(in)
  • Rotational Speed(rpm)
  • Cylinder Clearance (%)
  • Piston Rod Diameter(in)
  • Suction Pressure(psi)
  • Suction Temperature(°F)
  • Discharge Pressure(psi)
  • Gas Specific Heat Ratio
  • Gas Specific Gravity (Relative to air)
  • Compressor Mechanical Efficiency (0.95 – 0.98)
  • Z1 – Compressibility Factor at Suction Conditions
  • Z2 – Compressibility Factor at Discharge Conditions

PLTB Compressors 2.5_Input Rev_090120.png

 

 

Outputs/Reports

  1. View the results.
  2. If an input parameter needs to be edited be sure to hit the CALCULATE button after the change.
  3. To SAVE, fill out all required case details then click the SAVE button.
  4. To rename an existing file, click the SAVE As button. Provide all case info then click SAVE.
  5. To generate a REPORT, click the REPORT button.
  6. The user may export the Case/Report by clicking the Export to Excel/PowerPoint icon.
  7. To delete a case, click the DELETE icon near the top of the widget.

 

  • Piston Displacement(ft³/min)
  • Discharge Temperature(°F)
  • Z1 – Compressibility Factor at Suction
  • Z2 – Compressibility Factor at Discharge
  • Volumetric Efficiency (%)
  • Cylinder Capacity(ft³/min)
  • Equivalent Capacity(MMSCFD)
  • Cylinder Brake Horsepower Required(HP)

PLTB Compressors 2.5_Output Rev_090120.png

 

 

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