Mechanical Equipment Part 2

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7) Heat Exchangers:

  • Its purpose in a piping facility is to transfer heat from one commodity to another. 
  • Whether the objective is to heat a liquid to a desired temperature or cool a product for final storage, the exchanger can accomplish both. 
  • Exchangers do not mix commodities together, but rather transfer heat through contact with a surface of a different temperature. 
A number of exchanger types are available; they include:
Shell and Tube
Double Pipe
Reboiler
Air Fan

7.1 Shell & Tube Exchanger:

  • The shell and tube exchanger performs its task by circulating a hot liquid around tubes which contain a cooler liquid. 
  • The hot liquid circulates in an enclosed area called the shell. Tubes containing the cooler liquid are looped through the shell. 
  • Hot liquid in the shell warms the cooler liquid in the tubes, while the cooler liquid in the tubes cools the warm liquid in the shell.
7.2) Double Pipe Exchanger:

  • Also known as the G-Fin or hairpin exchanger, double pipe exchangers are manufactured with a single, small diameter pipe inserted into a larger diameter pipe. 
  • The two pipes contain commodities of different temperatures similar to the shell and tube exchanger. 
  • To prevent the two pipes of the exchanger from coming in contact with one another, thin metal plates called fins are welded to the outside of the smaller pipe.

8) Reboiler:

  • The reboiler, as the name implies, is used to replenish the temperature of a commodity.
  • Two types of reboilers are used; the kettle-type and thermosyphon. 
  • A kettle-type reboiler is similar in design to the shell and tube exchanger. 
  • The thermosyphon reboiler is attached directly to the bottom of a fractionating tower.
  • Reboilers are used to keep fluids, which are circulating  through a tower, at their boiling point.

9) Air Fan:

  • Air fans are large fan-type coolers placed above or below a pipe rack that draw air across pipes to cool them. 
  • Air fans operate on the same principle as an automobile's  radiator, only on a larger scale. 
  • Air fans can be as large as 20’-0 wide and 30’-0 long.
  •  If linked together, air fans can span up to 100 feet or more, running the entire length of a pipe rack.

10) Cooling Towers:

  • After circulating through equipment such as exchangers and condensers, cooling water will have accumulated substantial heat gain. 
  • Without dissipating the heat gain, cooling water will lose its cooling effectiveness. 
  • A cooling tower is a mechanical device that will lower the temperature of cooling water. 
  • Cooling towers are uniquely designed to dissipate heat gain by evaporating specific amounts of aerated water that has been circulated through an air-induced tower.
  • Although there is significant amount of drift (the amount of water lost during the aerating and evaporation sequence), Cooling towers are extremely efficient and are widely used.
11) Heaters/Boilers:

  • Heaters, or furnaces as they are also known, are used to raise the temperature of a feed stock to the point where it can be used in a process facility. 
  • Lining the interior walls of a heater are pipes that travel in a continuous S or U pattern. 
  • Burners, fueled with oil or gas, are used to generate the extreme temperatures required in a heater.
  • Heaters can be of the vertical or horizontal type
  • Boilers use the same principle of heater. They are used primarily to generate super heated steam or stripping steam.
  • Boilers can raise the temperature of water or condensate to 1000°F or more.

12) Storage Tanks:

  • Storage tanks are used in several phases of the refining process. They can be used to store crude oil prior to its use in the facility, as holding tanks for a partially refined product awaiting further processing, or to collect a finished product prior to its delivery or pick-up by a customer.
  • Usually placed within a common area of a facility known as tank farm, storage tanks comes in various shapes & sizes.
  • Spherical tanks are used for storing liquefied petroleum gases like butane, methane, or propane.
  • The larger tanks are used to store liquid product, will have either a conical, elliptical, open or floating roof.
  • Floating roofs help reduce evaporation and prevent the buildup of dangerous gases that often occur with inflammable liquids.





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