18 Questions
What happens if the LPG plant is not available?
Gas flow is sent to users via the LPG plant bypass
How many pressure control valves are configured in the LPG plant bypass?
2 x 100% pressure control valves
What type of metering system is used in the Feed Gas Metering Skid B-00301?
Custody transfer metering system
How is the opening of pressure control valves manipulated in the bypass systems?
By a reverse acting pressure controller downstream of the valve
Where is the Mirbat pipeline bypass located?
On the line going to Mirbat
What is the purpose of the pressure control valve settings in the bypass systems?
Set slightly below the normal pipeline pressure at that location
What is the purpose of the Inlet Gas Filter and Inlet Gas Separator in the plant facilities?
To remove black powder from the feed gas
What technology is used for Gas Dehydration in the plant facilities?
Molecular Sieve
Which system is involved in LPG Recovery in the plant facilities?
Ortloff Score Turbo-Expander technology
What is the function of the Residual Gas Metering system in the plant facilities?
Measure and monitor the flow rate of residual gas
Which system is involved in Sulfur Treatment Unit for LPG in the plant facilities?
Sulfur / Mercaptan Removal Bed
What is the primary function of the Gas Metering Skid in the plant facilities?
Accurately measure and control gas flow rates
What is the purpose of the Inlet Gas Separator V-11010?
To separate liquid hydrocarbons from the feed gas
What is the purpose of the pressure control valves (110-PCV-001A/004, 110-PIC-001A, 110-PIC-001B, and 110-PIC-004) on the Inlet Gas Separator?
To maintain a constant pressure in the separator
What is the purpose of the pressure protection systems (110-PIZ-003A/B/C and 110-PIZ-005A/B/C) on the Inlet Gas Separator?
To prevent excessive pressure buildup in the separator
What is the function of the Gas Chromatograph analysers (55AT-814 and 66-AI-815) in the feed gas system?
To analyze the composition and quality of the feed gas
What is the purpose of the Mercaptans and Water dew point analyser (121-AI-066C/121-AI-007) in the feed gas system?
To monitor the presence of mercaptans and water dew point
What is the purpose of the high-high H2S protection system (121-AIZ-006A/B) in the feed gas system?
To protect against excessive levels of hydrogen sulfide (H2S)
Study Notes
LPG Plant Bypass System
- If the LPG plant is unavailable, gas flow is sent to users via the LPG plant bypass, which has two systems: one at the LPG plant inlet and one on the line to Mirbat.
- Both bypass systems operate on bypass pressure control valve downstream pressure control.
- The bypass pressure controllers are set at a set point slightly below the normal pipeline pressure.
Feed Gas Metering Skid
- The Feed Gas Metering Skid B-00301 measures gas quantity from the 24” Salalah Gas Pipeline into Salalah LPG Plant.
- It includes a custody transfer metering system using feed gas flow meters 55-FI-780 and 55-FI-781.
Plant Facilities
- The plant facilities include:
- Black Powder Removal
- Feed Gas Fiscal Metering
- Free water removal and disposal
- Mercury removal using a sacrificial bed of metallic oxide
- Gas Dehydration Using Molecular Sieve
- LPG Recovery using proprietary “Ortloff Score” Turbo-Expander technology
- Sulfur / Mercaptan Removal Bed
- LPG Fractionation
- Recompression of residual gas from Deethanizer Column
- Condensate (C5+) stabilization, rundown storage, pumping, and loading
- Residual Gas Fiscal Metering
- Separate propane and butane, rundown, storage, loading, and fiscal grade flow measurement
- Domestic LPG blending using 10% of total C3 & C4 product
Inlet Gas Filter and Separator
- Inlet Gas Filter Unit F-00201/F-00202 receives gas from the Gas Transportation Facilities (GTF) through the 24” Salalah Gas Pipeline, with an expected pressure range of 50 barg to 90 barg.
- Gas Chromatograph analysers 55AT-814 and 66-AI-815 analyse feed gas quality.
- Mercaptans and Water dew point analyser 121-AI-066C/121-AI-007 analyse Mercaptans and Water dew point.
- High-High H2S contents in feed gas flows are protected by 121-AIZ-006A/B.
Inlet Gas Separator
- Inlet Gas Separator V-11010 maintains a pressure range of 50 barg to 60 barg using pressure control valves 110-PCV-001A/004.
- The separator has a reverse acting pressure control pressure valve 110-PIC-001A installed on the separator inlet line with a set point of 60 barg.
- A second pressure control valve 110-PIC-001B provides direct acting control with a set point of 62 barg.
- The third pressure control 110-PIC-004 is reverse acting with a set point 2 barg lesser than the set point of 110-PIC-001A as a redundant system.
Explore the operation of LPG plant bypass systems when the plant is unavailable due to maintenance or other reasons. Understand the use of bypass pressure control valves to regulate gas flow to users via the bypass systems.
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