POWER PLANT:Gas Separators/Filters

 

power-plant

Gas Separators/Filters

i.  Skid mounted gas separator/filter unit shall be supplied to remove asphalt sand, wax material, and other gas bore contaminants (black powder) having a particle size of 3 microns and larger as well as liquid hydrocarbons and water, as per the applicable Saudi Aramco standards.

  The gas separator/filter unit shall consist of four (4) separators (three in service and one standby) complete with interconnecting piping, valves, and instruments.

 

The skid arrangement shall be designed to allow separators to normally run in parallel or independently when one or more separator/filter(s) is out of service for maintenance.

ii)   It is pertinent to note that the Owner is facing the problem of excessive black powder collected at the filtration units of some existing plants, so the bidders shall give special emphasis on the design of filter separators to cater to this problem.

iii.  In this regard, the bidders shall submit a detailed report with their proposals  about the remedial measures to be built in the design of the filter separators, in order to take care of the excessive black powder problem.

iv.   The salient design parameters shall be:
1)         Design Conditions:
1st       Pressure           Max.      -           1060 psi (73 bar)
                                    Min.         -           7.5 psi (vacuum)
)            (0.5 bar, vacuum)
2nd      Temperature       -           200F (93 C)
3rd       Min. Design Metal Temp.          -           20F (-6.66 C)
4th       Design Code      -   ASME Section VIII Div. I
5th       Corrosion Allowance    2  -   3mm

         Operating Conditions:

1st       Service       -    Natural Gas
2nd      Pressure       -     Minimum 450 PSIG,                                                                                                (31 bar), maximum 
          770 PSI (53 bar)
3rd       Temperature       -   Minimum 32F, (0C)                                                                                                maximum 130F (50C)
4th       Flow rate      -   As per fuel gas requirement                                                                                      considering three separators
                                                                                     in service and one standby.
5th       Efficiency                      -           98% of all liquid droplets and
                                                                                     entrained solid particles of 3
                                                                                     microns size and larger

    Scraping Facilities a]   Scraper Traps 

i.   A permanent scraper station shall be installed on the pipeline, as periodic scraping is required for corrosion control of the pipeline, and removal of solid & liquid build-up in the gas line.

ii.     The term "scraper" includes all devices for internal cleaning, gauging, inspection (instrumented tools), batching, and inflatable spheres. 

The term "traps" refers to the devices used for launching or receiving the scrapers.

iii.   Scrapping facilities comprising one (1) scraper station at each end, capable of launching/ receiving instrumented scrapers with related facilities including all valves, instrumented scrapers, passage indicators, etc. shall be provided for the pipeline.

iv.  The scraper launcher shall be installed at the beginning of the pipeline near the tie-in point

 

b]   Design Requirements             

 

i.  Scraper traps

ii.   Scraper trap station piping for onstream scraping operations shall be provided in compliance

iii.   Scraper Stations shall be provided in accordance:

1)Full bore isolation valves of the same nominal size as the pipeline at both ends.

2) A barred tee in the mainline near each scraper station.

3)    A bypass line, between the tie line valve and the trap, with a kicker valve and a second block valve to provide tight shut-off in the bypass line.

4)  A blinded valve for the hydro test.

5) A double-valved drain system sized to permit drainage of the trap.

6)  A vent system to provide safe disposal of gas and vapors through burn pit/flare before the trap closure is opened.

7) A purge connection on scraper launcher as well as receiver
8)         Sample connections.

9)         A pressure gauge near the trap closure and one on the mainline near the trap isolation valve
10)       A flush connection each on scraper launcher and receiver.  end, potable water shall be tapped from facilities through a permanent connection whereas the provision shall be made for hook up with a tanker truck.

iv. Scraper passage indicators

v.  The proposed pipeline shall not have valves, fittings or connections installed, that may impede the travel of the scraper.

vi.   Scraper traps shall be provided with tight sealing end closures and locking mechanism of the closure shall be of the clamp-ring or band lock type.

vii.  The closure locking mechanism shall be provided with a pressure warning safety interlock device, which must be opened before the closure mechanism can be unlocked. 

Closing of the pressure warning safety interlock shall not be possible until the closure locking mechanism is fully engaged and locked.

viii.   All closure doors shall be supported by adjustable hinges or an adjustable davit.

ix.   The required clearance area for the door shall be indicated by the Contractor.

x., In order to provide mechanical assistance to
break the seal when opening the door and compress the seal when closing the
door, all required tools shall be included in the delivery and suitable
attachment lugs for the tools shall be provided where necessary.

xi.   Platforms shall be provided for easy access to valve actuators and closure operating mechanism.  All valves shall be accessible at least from one side of the trap.

xii.   A mechanical scraper-loading device with a suitable lift and span shall be provided to assist in the loading and the receiving normal cleaning and batching scrapers.