Strainers and Filters Flashcards
TERMINAL OBJECTIVE:
1
Under all plant operating conditions, describe the purpose and operation of Filters, Strainers, and Ion Exchangers used at PVGS in accordance with station documents and procedures.
ANSWER ALL CARDS
1.1
Describe the purpose of Strainers and Filters
Strainers and Filters accomplish the same principle; mechanical separation of particulate and debris from a process flow to protect equipment.
- Strainers remove particulates that are larger than 40 microns (40 μm).
- Filters remove particulate smaller than 40 microns.
1.2
Describe operation of Strainers used at PVGS.
Basket Strainers
These are larger strainers constructed to remove large particulates from high-volume processes where narrower strainers would cause backup. The increased surface area allows a higher flow rate without a rise in differential pressure across the strainer.
Y type Strainers
These Strainers contain an in-line screen, angled downward to form a “Y” shape, to trap particulate. They are compact and very strong, making them able to handle high pressures. The basket contains an opening at the bottom to be able to flush the Strainer.
1.3
Describe the operation of Filters used at PVGS.
Cartridge Filters
A Cartridge filter housing may contain one or many individual cartridges, depending on the required flow rate. The cartridges may be constructed of various materials depending on the requirements. Often times, the cartridges are perforated metal cylinders and usually have a fiber yarn wound around them. At PVGS, pleated paper cartridges are used in the Instrument Air and Main Generator Seal Oil systems to remove particulate while the Gas Turbine Generator Fuel Oil subsystem uses synthetic materials to separate water from the fuel oil.
Deep Bed Filters
These Filters are contained in a large cylindrical or spherical tanks. They utilize a bed of sand and/or anthracite (crushed hard coal) and gravity flow to mechanically separate particulate from the water. Water enters through the inlet header, above the media, and is dispersed via a distribution plate. The water flows down through the media, which is placed on the top of a perforated deck. The filtered water passes through the deck and travels to the upper portion of the filter housing, and out the discharge header at the top of the housing.
The level of water maintained in the upper housing is periodically used to backwash the filter media. During the backwash, water flows through the media in a reverse direction, dislodging the accumulated particulate, and is discharged via a backwash valve on the inlet of the filter.
Stacked Disc Metal Edged Filters
These filters are used for the filtration of complicated, viscous or gel-like media such as oil. A stack of discs and spacers is closed on one end with the opposite end connected to the filter discharge. The fluid penetrates while the particulate is trapped by the discs.
The filter can be cleaned without interrupting process flow by turning the handle on the top 1 full turn. Turning the cartridge handle rotates the discs and spacer assembly past the fixed cleaner blades which extend into the openings between the discs. Thus, by rotating the disc and spacer assembly one revolution, in either direction, all particles lodged on or between discs are carries to the cleaner blades and are positively removed from the surface of the filter cartridge without interruption of flow. Particulate falls to the bottom of the filter sump which can then be drained.
1.3
Describe the operation of STACKED DISC Filters used at PVGS.
Stacked Disc Metal Edged Filters
These filters are used for the filtration of complicated, viscous or gel-like media such as oil. A stack of discs and spacers is closed on one end with the opposite end connected to the filter discharge. The fluid penetrates while the particulate is trapped by the discs.
The filter can be cleaned without interrupting process flow by turning the handle on the top 1 full turn. Turning the cartridge handle rotates the discs and spacer assembly past the fixed cleaner blades which extend into the openings between the discs. Thus, by rotating the disc and spacer assembly one revolution, in either direction, all particles lodged on or between discs are carries to the cleaner blades and are positively removed from the surface of the filter cartridge without interruption of flow. Particulate falls to the bottom of the filter sump which can then be drained.
1.3
Describe the operation of Filters used at PVGS.
Cartridge Filters
A Cartridge filter housing may contain one or many individual cartridges, depending on the required flow rate. The cartridges may be constructed of various materials depending on the requirements. Often times, the cartridges are perforated metal cylinders and usually have a fiber yarn wound around them. At PVGS, pleated paper cartridges are used in the Instrument Air and Main Generator Seal Oil systems to remove particulate while the Gas Turbine Generator Fuel Oil subsystem uses synthetic materials to separate water from the fuel oil.
Deep Bed Filters
These Filters are contained in a large cylindrical or spherical tanks. They utilize a bed of sand and/or anthracite (crushed hard coal) and gravity flow to mechanically separate particulate from the water. Water enters through the inlet header, above the media, and is dispersed via a distribution plate. The water flows down through the media, which is placed on the top of a perforated deck. The filtered water passes through the deck and travels to the upper portion of the filter housing, and out the discharge header at the top of the housing.
The level of water maintained in the upper housing is periodically used to backwash the filter media. During the backwash, water flows through the media in a reverse direction, dislodging the accumulated particulate, and is discharged via a backwash valve on the inlet of the filter.
Stacked Disc Metal Edged Filters
These filters are used for the filtration of complicated, viscous or gel-like media such as oil. A stack of discs and spacers is closed on one end with the opposite end connected to the filter discharge. The fluid penetrates while the particulate is trapped by the discs.
The filter can be cleaned without interrupting process flow by turning the handle on the top 1 full turn. Turning the cartridge handle rotates the discs and spacer assembly past the fixed cleaner blades which extend into the openings between the discs. Thus, by rotating the disc and spacer assembly one revolution, in either direction, all particles lodged on or between discs are carries to the cleaner blades and are positively removed from the surface of the filter cartridge without interruption of flow. Particulate falls to the bottom of the filter sump which can then be drained.
1.3
Describe the operation of DEEP BED Filters used at PVGS.
Deep Bed Filters
These Filters are contained in a large cylindrical or spherical tanks. They utilize a bed of sand and/or anthracite (crushed hard coal) and gravity flow to mechanically separate particulate from the water. Water enters through the inlet header, above the media, and is dispersed via a distribution plate. The water flows down through the media, which is placed on the top of a perforated deck. The filtered water passes through the deck and travels to the upper portion of the filter housing, and out the discharge header at the top of the housing.
The level of water maintained in the upper housing is periodically used to backwash the filter media. During the backwash, water flows through the media in a reverse direction, dislodging the accumulated particulate, and is discharged via a backwash valve on the inlet of the filter.
1.3
Describe the operation of CARTRIDGE Filters used at PVGS.
Cartridge Filters
A Cartridge filter housing may contain one or many individual cartridges, depending on the required flow rate. The cartridges may be constructed of various materials depending on the requirements. Often times, the cartridges are perforated metal cylinders and usually have a fiber yarn wound around them. At PVGS, pleated paper cartridges are used in the Instrument Air and Main Generator Seal Oil systems to remove particulate while the Gas Turbine Generator Fuel Oil subsystem uses synthetic materials to separate water from the fuel oil.
1.4
Explain the meaning of abnormal differential pressure across Strainers and Filters.
As a process flows through a Filter or Strainer at a particular pressure, and particulate is collected by the media, the downstream pressure will drop. The filter is becoming clogged and reducing the flow through the Filter or Strainer. This means that the differential pressure across the filter (upstream pressure – downstream pressure) will increase. Therefore, raising differential pressure across a Filter or Strainer indicates that it is becoming clogged.
If the differential pressure across a Filter or Strainer goes down, instead of up, that would mean that the Filter or Strainer has been torn, and is allowing process flow and particulate to pass through unfiltered.
