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Category: Energy

Cargo Emergency Shut Down System in Liquefied Gas Carrier

Rifka Aisyah Leave a comment

I am interested in designing ship-to-shore link and ESD arrangement in LNG vessel. I have involved in about three LNG projects, but I did not design or paid more attention in this field (because all the projects were front-end engineering design). In this post, I want to share you practical information about ESD arrangement as suggested by SIGTTO (Society of International Gas Tanker and Terminal Operators).

Function of Emergency Shut Down System

Function of cargo ESD system is to stop cargo liquid and vapor flow in the event of emergency and to bring the cargo handling system to safe condition. Read More

Methane number empirical models

Understanding Methane Number

Rifka Aisyah 1 Comment

In my previous LNG project, we need to supply gas with specified minimum methane number and specified higher heating value.

What is methane number?

It is the measure of resistance of fuel gases to engine knock, known as detonation. Detonation is produced by the auto-ignition of fuel/air mixture ahead of the propagating flame. Detonation must be immediately stopped to avoid increase of wear and tear and engine damage.

If MN is too low, the detonation can reduce engine efficiency and increases the quantity of harmful engine emissions.

MN Calculation

I searched if there is formula for the calculation, but I cannot find it. MN is not gas thermodynamic property, so no equation of state can be used to calculate it. I found there are several online methane number calculators. I tested three of them, Cummin, Wartsilla, and DNV MN calculator, respectively by using LNG Tangguh composition. These are the results.

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Natural Gas Quality Designation Parameters

Rifka Aisyah Leave a comment

When I was working on my second EPC project in Senoro, which was gas processing facility, I read that there are several natural gas quality that shall be complied. In the project, we also had to guarantee that the facilities can process gas from wells so that it met requirement as stated in contract. In this post, I want to share you the quality designation parameters for natural gas. To understand more about this area, please check ISO 13686: Natural Gas – Quality Designation.

Natural gas quality designation parameter
Natural gas quality designation parameter

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Regulating Sector

Regulating Sector at City Gas Distribution System – Understanding

Rifka Aisyah Leave a comment

This is the forth post of city gas series. Check my previous post about how to calculate city gas flow rate, city gas network part 1, and understanding metering and regulating station. In this post, I want to share you about regulating sector. 

Before being distributed to house, gas pressure and gas flow from tapping point will be monitored in metering and regulation station (MRS). After leaving MRS, gas will be distributed via distribution pipeline which is usually MDPE pipe.

In my project we use 63 mm pipe or 90 mm pipe for distribution pipeline.

Gas distribution is usually grouped. Each group covers several houses, which can be as low as 900 houses to 2000 houses. In each group, we installed regulating sector.  Read More

Example metering and regulation station

Understanding Metering and Regulating Stations and Its Part

Rifka Aisyah Leave a comment

This is the third post of city gas series. Please check the first post about how to calculate city gas requirement and the second post about city gas distribution network part 1. 

In previous post, I share you one important part of city gas distribution equipment which is Metering and Regulating Stations (MRS). For review, the function of MRS is to monitor flow rate of gas and to reduce gas pressure thus it meets requirement. Gas pressure is reduced from more than 16 bar to 5-15 bar in MRS. I checked in “City Gas Network Handbook” published by Indonesian Government, maximum pressure of city gas distribution system is 7 bar, although in reality, gas operating pressure is not that high. Read More

City gas network

City Gas Distribution Network (Part 1)

Rifka Aisyah Leave a comment

This is second post of city gas network series. For the first post, please check “City Gas Flowrate Requirement”.

City gas distribution is one of Indonesia national priority program which purpose is to diversify energy, to reduce energy subsidiary, to provide clean and cheap energy, and as complementary program to convert cerosene into Liquified Petroleum Gas (LPG).

The total installed city gas until now is 56,888 house connection. It will be increased year by year. For example in 2013, the government planned to installed 16,000 connection. Read More

Economic of comparison vacuum insulated tank and flat bottom tank

Comparison of LNG Flat Bottom Tank and Vacuum Insulated Tank

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In previous post (typical process flow diagram of small scale LNG regasification facility), I explained that LNG storage tank played important part in the facility. It is used to stored LNG for certain duration (usually in term of round trip). In small scale LNG regasification facilities, vacuum insulated tank is usually used because the capacity if small. But when the capacity is high, LNG flat bottom tank is used.

In this post I want to share you difference and comparison between LNG flat bottom tank and vacuum insulated tank and give some advice what to choose.

Table below shows comparison of flat bottom storage tank and vacuum insulated tank. Read More

Schematic of LNG single containment flat bottom tank part 2 (EN 1473)

Flat Bottom Storage Tank – Different Types and Its Features

Rifka Aisyah 1 Comment

In my third LNG project, I had a chance to meet two different LNG storage tank vendors. One vendor produce vacuum insulated  storage tank (pressurized type) and the other one produce flat bottom storage tank (atmospheric type).

During the meeting I got several terms of  LNG flat bottom storage tank types, such as single containment tank, double containment tank, and full containment tank. What was that?

In this post I want to share you different types of LNG flat bottom storage tank and its special features. Read More