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Stage Separation of Gas-Condensate

Stage separation of gas-condensate is a process in which hydrocarbon mixtures are separated into vapor and liquid phases by flashing to low pressure in several steps. Main purposes of stage separation are:

  1. To obtain a more stable stock-tank liquid
  2. To increase liquid recovery

Figure below shows typical stage separation process.

Stage Separation Process

I want to share to you some terminology that I also just knew about stage separation. A two-stage separation requires one separator and one storage tank, and a three-stage separation requires two separators and one storage tank. I never thought before that the storage tank is always counted as final stage of vapor-liquid separation. Read More

Design of Shell and Tube Heat Exchanger – Tube Side Construction

In my previous post, design of shell and tube heat exchanger – layout design, I shared how to select fluid allocation, which one should be in tube side and which one should be shell side, general rule for allowable fluid velocity, pressure drop, and temperature approach. This post will be the continuation of design of shell and tube heat exchanger series, which specifically explain about construction detail in tube side.

Want to learn from the beginning?
Read my first post about step-by-step design of shell and tube heat exchanger. Still curious? Read my second about about layout design of shell and tube heat exchanger.


This is mind map of this topic.

Design of shell and tube heat exchanger - tube design
Design of shell and tube heat exchanger – tube design

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Design of Shell and Tube Heat Exchanger

It’s been quite a long time since the last time I saw and designed shell and tube heat exchanger. Recently, I got opportunity to dig and refresh knowledge that type of heat exchanger. In this post, I want to share you about design of shell and tube heat exchanger.

This figure shows you general step-by-step method of design of shell and tube heat exchanger.

Design of shell and tube heat exchanger
Design of shell and tube heat exchanger

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Application Range of Variety of Compressors and Compressor Selection

When I was involved in pre-FEED of well production and gas treatment, one of key deliverable is compressor studyIn this post, I want to share you about application range of variety of compressors (reciprocating, compressor, and axial-flow). In addition, I will also share the differences between those compressors.

Application Range of Variety of Compressors

Figure below can estimate application range of variety of compressors. It is a function of inlet flow in actual cubic feet per minute and discharge pressure in psia. 

Application range of variety of compressors
Application range of variety of compressors (source: Rules of Thumb of Chemical Engineers, Branan)

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How to Calculate NSPH of Pump with Examples and Illustrations

NPSH of pump (net positive suction head) should be calculated/predicted in the beginning of pump sizing. The purpose is to check if the pump will work appropriately. Liquid pressure will lower right in inlet of pump impeller. If pressure reduction is lower than vapor pressure, liquid phase will change to vapor phase. The impeller rapidly collapses vapor bubbles which cause cavitation and damage.

In this post I will share you how to calculate NPSH available, which is net positive suction head calculated based on system arrangement. The value of NPSH available (NPSHA) shall be greater than NPSH required (NPSHR), which is a function of pump and to be specified by pump manufacturer.

NSPH of pump is calculated as follow:

NPSH available (ft, m) = absolute pressure (ft, m)vapor pressure (ft, m) –  line loss (ft, m) ± elevation difference (ft, m) Read More

Centrifugal Compressor Power Calculation

In this post I want to share you how to calculate centrifugal compressor power since there are so many process engineers are looking for it (and I also don’t know how).

To calculate centrifugal compressor power, we need these gas properties: compressibility factor (Z), molecular weight (MW), inlet gas temperature, inlet gas pressure, outlet gas pressure, adiabatic component (Cp/Cv), and mass flow rate.

Let’s start with an example while I show you step-by-step of the calculation method. In this example, we have these gas properties (I use US units).

Compressibility factor (Z) = 0.9972

Molecular weight (MW) = 18.15

Gas constant (R) = 1544/molecular weight

Inlet temperature (T1)  = 546 deg R

Inlet pressure (P1) = 15 psia (don’t forget to use absolute pressure)

Outlet pressure (P2) = 60 psia

K (Cp/Cv) = 1,274

Flow (W) = 0,184 lb/min

The required data to calculate centrifugal compressor power is head. We can use either adiabatic head or polytropic head as long as we use adiabatic efficiency and polytropic efficiency in companion. Read More

Centrifugal Pump Sizing Spreadsheet

Since past two days, people still celebrate new year, so office activity has not started yet. That means I actually still in holiday too. But I want to update this blog while enjoying my holiday. I cannot (or in a mood) to create full article. So, instead sharing full article, in this post, I want to share you centrifugal pump sizing spreadsheet.

I created pump sizing spreadsheet for my first LNG project. The inspiration came from Pump Sizing Calculation from CheCalc. But I made it better.

I think you should download this spreadsheet because it offers better features that online calculation fro CheCalc. 

  • The spreadsheet is simple. You just input the data in dark yellow highlight
  • Pump sizing is calculated based on rated flow rate. If you want to size based on normal flow rate, input 0 in percentage of rated flow rate
  • Pressure drop components is comprehensive, including pipe loss, fitting loss, and equipment loss
  • Pump data results is comprehensive, including:
    • Suction pressure
    • Discharge pressure
    • Differential pressure
    • Differential head
    • Hydraulic power
    • Pump BHP
    • Rated power (calculated)
    • Rated power (selected) : based on commercial output motor power
    • NPSHA
    • NPSHR
    • Shut in pressure

Stop reading! Start downloading! Hope you find this useful!

[button style=”btn-default btn-sm” icon=”glyphicon glyphicon-save” align=”left” iconcolor=”#4285bf” type=”link” target=”false” title=”Download Pump Sizing” link=”″]


How to Properly Size Discharge Pressure of Pump

When sizing discharge pressure of pump, we need to consider at least two things: target pressure at destination point and pressure loss from source point to destination point. How if we have two different destination points? How do we properly size pump discharge pressure?

In this post I want to share you simple method to size discharge pressure of pump when you have more than one destination point. Read More