The location of pumps may vary for many reasons. The primary goal in setting pump location is to minimize the length Of the suction piping while satisfying the piping flexibility requirements as well as
allowable loads that may be subjected to the nozzles.
Following drawing deals with pumps along and under main pipe racks at various locations. Following figure displays the typical pump elevations.
- Pumps 1A, 1B, 2A and 2B are located under the main overhead pipe rack. This is a common location within many plants with a minimum potential for hydrocarbon leaks to the electric motors. (Hydrocarbon-bearing air coolers located over pipe racks are a concern for many clients.) This location provides an effective means for adding support steel from the pipe rack.
- Pumps 3A, 3B, 4A, and 4B are partially located under the pipe rack, with the casing set outside the column line. In this arrangement, the discharge piping can rise into the vertical slot that is usually provided for lines entering or leaving the pipe rack, as shown below.
- Pumps 5A, 5B, 6A and 6B are located outside the confines of the pipe rack. This is the usual arrangement when hydrocarbon spills are more likely.
- Pumps 7A, 7B, 8A and 8B are located directly under the process equipment that they serve, which is supported in the structure above.
Drums and shell and tube exchangers are less associated with dangerous spills and therefore may have pumps located directly beneath them. Supporting pump piping is also facilitated by the proximity of the steel.
Pumps 9a, Band C and 10A, B and C are inline and are treated basically as a piping item (e.g. a control valve). Adequate access must be planned to the pump and drive, which may be removed for maintenance. Locating Boiler Feed Pumps
Because boiler feed pumps take water from a deaerator and generally operate close to the vapor pressure of the liquid, they must be located as close to the deaerator as possible.
Locating Vertical Pumps
Vertical pumps are used when NPSH requirements make using horizontal pumps impractical.
Following drawing shows a typical condensate pump that is located adjacent to the surface condenser it serves.
Following drawing depicts a sump pump that is generally used to remove waste material collected in a concrete or steel pit.
A screen at the bottom of the pump suction connection reduces the possibility that the pump will foul during operation.
The discharge connection may be piped to another holding vessel, a pond or a waste removal vehicle.
Centrifugal pumps in vacuum service are shown below.
Because the system operates at the negative pressure and extremely high temperatures, the location of these pumps must be either directly under the tower or just outside the support columns.
When the pumps are located directly under the tower, it may be necessary to support the pumps with springs, as shown below. This essentially consists of a steel frame with four spring supports attached to the sides. The pump is then set into the steel frame and secured. During operation, the pump is free to move within the design limits of the four springs, reducing the stress imposed on the nozzles by high temperatures.