Question: The design of a processing plant is being considered for development. In this plant, ten large centrifugal compressors will be used for water cooling. Refined lubricating oil will be required at a rate of 5 gpm for each compressor. The lubricating oil will be refined onsite to ensure that the content of unsaturated hydrocarbons in the oil will be low to prevent damage to the compressors. Due to the large number of compressors and auxiliary equipment required for the refinement of the oil, it has been proposed to use two separate buildings to house the compressors and oil refinement equipment. The sketch below shows the distance between the buildings. As an initial design concept, it has been suggested to transport the refined oil from an 11-ft-diameter vented storage tank in Building 1 to the main header line feeding the compressors in Building 2.
To manage construction costs, the outdoor piping between the buildings will not be buried and will be mounted 1¼ ft above grade. For this location, the average outdoor temperature in the summer is 80?F and in the winter, it is -5?F. The average wind speed in winter is about 9 mph (miles per hour). For the lubricating oil, the pour point (temperature at which oil ceases to flow) is approximately 20?F and the flash point (temperature at which oil vapor will ignite when exposed to a flame) is 400?F. For improved operation of the compressors, the oil temperature and pressure at the inlet to the main header line shall be no less than 70?F and 20 psig, respectively. Design a piping system, up to the main header line feeding the compressors, and specify the information that will be required for the selection of equipment (including equipment for heating) needed to facilitate transportation of the oil from the storage tank in Building 1 to the main header line of the compressors in Building 2. Given the preliminary stage of this design, no equipment schedules or catalog sheets are required. Useful Property Data for Standard Lubricating Oil: Density of 58 lb/ft3; kinematic viscosity of 3.8 cSt = 4.09×10-5 ft2/s; specific heat of 0.450 Btu/(lb R); thermal conductivity of 0.087 Btu/(h ft R); vapor pressure of 0.030 psi. Further Information: Special heaters for oil are available that come complete with a vented tank and burner, only. Typical heater heights will be between 3 and 6 ft.
