materi kuliah teknik kimia

FLUID MECHANICS PROBLEMS A 90 per cent by weight solution of ethyl alcohol in water is to pumped from storage tank to a process department through a 1 1/4-in. standard iron pipe 1450 ft long. The line contains 15 standard elbows, 5 gate valves, 6 standard tees and 4 tees through a side outlet. The process end of the line must have a pressure of 8 psig and is 22 ft above the storage tank. The temperature of the line can be taken at 77 oF as the lowest it will possibly attain, and the flow will be rated at 20 gpm, but it may be overloaded by 50 per cent. Assuming 60 per cent total pump efficiency, at average Rp. 750 /kwh, calculate the annually cost of the system! Water is flowing at a rate 80 gpm through 50 ft of an annular conduit made of ½-in. and 11/4-in. schedule-40 commercial steel pipe. What is the pressure drop (lb/in2) in the 50 ft? Assume, as average properties, a density of 62.3 lb/ft3 and a viscosity of 0,88 centipoise. A liquid with an effective average density of 0,8 gram/cc and an effective viscosity of 0,8 centipoise is to be ump through a straight, smooth, copper heat exchanger of annular cross section at a linier velocity of 10 fps. The outer diameter of the inner wall of the annulus is exactly 1 in.; the inner diameter of the outer wall of annulus is exactly 11/2in. The length of the exchanger is 20 ft. What is the drop in pressure (lb/in2) from friction within the annulus? Water is retained in small mountain lake whose surface is 280 ft above the inlet to the turbines in a power house. Surveyor have laid out the best line location for the piping system to bring the water down to the power house, he route being 3.100 ft long. What is the minimum standard diameter of pipe which may be used in the line so that the natural flow will be 1000 gpm and the pressure at the turbine nozzles will be 100 psig. The normal water temperatur is 40 oF. A standard 2-in. pipe is conveying an oil of average specific gravity of 0,850 at a rate of 20 gpm. At a certain point in the line the static pressure is 45 psig. Estimate the static pressure at a point in the line which is 200 ft of the pipe further along in the direction of floe and which is 50 ft lower in elevation. The oil has a viscosity of 20 centipoises at the temperature of flow. Water at 60 oF is pumped from tank T to tans M and N. The line from tank T to pump inlet is 3-in.schedule-40 pipe, with an equivalent length of 200 ft. The line from the pump discharge to the tee where the line branches is also 3-in. schedule 40 pipe, with an equivalent length of 100 ft. The line from the tee to tank M is 11/2-inschedule-40 pipe, with an equivalent length of 600 ft. The line from the tee to the tank N is 2-in, schedule-40 pipe, with equivalent length of 600 ft. The equivalent lengths as given do not include four gate valves, one between tank T and the pump, one between the pump and the tee, and one each at tanks M and N; and two globe valves, A in line from tee to tank M, and B in line from the tee to tank N. All valves are wide open except either A or B, one of which is throttled to give the rate of flow of 50 gpm to tank M and 90 gpm to tank N. The water level in tank T is 30 ft above the pump inlet, and the levels in tank M and N are each 8 ft above the pump inlet. Assume average cost Rp. 250 per kilowatthour. What is the horsepower and cost requirement of the pump Calculated the flow of oil in gallons per minute through a standard sharp-edged orifice 5/8 in. diameter. The chambers to the orifice are four times the orifice diameter. The oil has a specific gravity of 0,85 and a viscosity of 11 centipoises. The pressure drop across the orifice is measured by a mercury manometer located underneath the orifice meter. The reading on the manometer is 9 in. In order to determine the quantity of air flowing through a circular duct whose internal diameter is 20 in., pitot tube reading were taken along diameters at right anggles to each other is across section of the the duct. The data presented in the table below. The air was flowing at an absolute pressure of 735 mm of mercury and at a temperatur of 250 oF. The pitot tube coefficient was 0,98. Calculate the rate of flow of the air in cubic feet per minute, measured at 760 mm and 60 oF. Construct a graph showing the variation of the ratio of local velocity to central velocity with the distance from the center of the duct. Point Location, in. from center of duct Pitot tube reading, in water Point Location, in. from center of duct Pitot tube reading, in water Point Location, in. from center of duct Pitot tube reading, in water Point Location, in. from center of duct Pitot tube reading, in water 9.75 0.198 3.00 3.38 9.00 0.850 7.00 1.95 9.00 0.800 5.00 2.81 8.00 1.48 8.00 1.45 8.00 1.40 7.00 2.10 7.00 2.02 9.00 0.872 7.00 1.90 8.00 1.56 5.00 2.73 9.75 0.200 5.00 2.67 9.00 0.891 3.00 3.32 3.00 3.27 9.75 0.210 3.00 3.31 0.00 3.67 9.75 0.205 5.00 2.75 Water at 50 oF is flowing through 3-in. schedule-40 pipe at a rate of 150 gpm. if a standard sharp-edged orifice 13/4 in. diameter is inserted in the line, what would be the reading on a mercury manometer connected across the orifice? If a venturi meter with a throat 13/4 in diameter were use instead of the orifice, what would the manometer read? What would be the reading on each instrument if, instead of the water, an oil was flowing through the pipe at the same rate, the oil having a density of 0,890 gm/cc and a viscosity of 1.30 centipoises? A 2-in. schedule-40 pipe line carries water at 70 oF. A sharp-edged orifice (1,077 in. diameter) serves as the primary element of a flowmeter. The secondary element is a mercury-water manometer whose two branches have a difference in level of 22 in. at maximum flow. The manometer is to be inverted and used as an air-water manometer, maintaining the 22-in. differential at the maximum flow. What new orifice diameter is needed?

materi kuliah teknik kimia

Minggu, 01 Desember 2013

Proses Industri Kimia 2

Proses Industri Kimia

FLUID MECHANICS PROBLEMS