Pumping boron tribromide into a process tank Learning object

Pumping boron tribromide into a process tank Learning objective: Use of the mechanical energy balance to determine pump power and pressure rise required for a fluid flow process. Boron tribromide BBr_3 is a strong Lewis acid that is useful dealkylating agent in the production of pharmaceuticals. A former researcher of mine who was experienced with organic synthesis. Justin Smith, used this in my lab. I had the leftover material removed from our lab once he was done with the synthesis because of the following statements on its Material Safety Data Sheet (MSDS): \"lt (BBr_3) may react violently with water to emit toxic gases or it may become self-reactive under conditions of shock or increase in temperature or pressure...Extremely hazardous in case of skin contact (irritant), of inhalation (lung irritant). Very hazardous in case of digestion. Slightly hazardous in case of skin contact (corrosive, permeator).* The pharmaceutical company you work for has asked you to determine the brake horsepower required for a pump to send 15 gal/min of boron tribromide (specific gravity of 2.64 and mu = 7.3 times 10^4 Pa-s) at 68 degree F from a tank at atmospheric pressure through 1000 ft of 2 inch schedule 40 steel pipe into a sealed reactor at 10 psig, where the level is 10 ft above that m the lower tank. The typical pump efficiency used for such a process is 70%. Determine the pump brake horsepower required. What is the pressure rise across the pump?

Solution

Q of flow = 15 gal/min, Specific weight = 2.64 , viscosity = 7.3 x 104 pa s at 68 deg F

Height to be pumped = 10ft, length of pipe = 1000ft, Pressure in the reactor = 10psig.

the friction coefficient for thesteel pipe is obtained as 0.11 fron chart,

The loss due to 1000ft long pipe = flvxv/2gd = 4x 0.11 x1000x(5.83 x60^2/ 2x 32 x2 = .039 f

The tank is 10 ft above hence net head is .39= 10.39 ft

BHP = sp. gravity x Q in cubic feet/min x HEAD/ 33000 = 2.64x 15x .1661x 10.39/33000 = 184 hp ( 1 gal o fwatwer = 80 lb)

The pressure at the pump is 10.39ft of water+10psi= 9.56 +10 = 19.56psi