Chemical Engineering Answers

A process fluid is pumped from the bottom of one distillation column to another, using a centrifugal pump. The line is standard commercial steel pipe 75 mm internal diameter. From the column to the pump inlet, the line is 25 m long and contains 6 standard elbows and a fully open gate valve. From the pump outlet to the second column, the line is 250 m long and contains 10 standard elbows, 4 gate valves (operated fully open), and a flow-control valve. The fluid level in the first column is 4 m above the pump inlet. The feed point of the second column is 6 m above the pump inlet. The operating pressure in the first column is 1.05 bara and that of the second column 0.3 barg. Determine the operating point on the pump characteristic curve when the flow is such that the pressure drop across the control valve is 35 kN=m2. The physical properties of the fluid are density 875 kg=m3 , viscosity 1:46 mN m2s. Also,

A process has a distillation column, where a crude dichlorobenzene is pumped from a storage tank. Nitrogen is used to blanketing the column and the pressure above the liquid surface is held constant at 0.1 bar gauge pressure. The minimum depth of liquid in the tank is 1 m. The distillation column operates at a pressure of 500 mmHg. The feed point to the column is 16 m above the base of the tank. The tank and column are connected by a 50 mm internal diameter commercial steel pipe, 220 m long. The pipe run from the tank to the column contains the following valves and fittings: 20 standard radius 90° elbows: two gate valves to isolate the pump an orifice plate and a flow-control valve. If the maximum flow-rate required is 20,000 kg/h, calculate the pump motor rating (power) needed. Take the pump efficiency as 70 per cent and allow for a pressure drop of 0.5 bar across the control valve and a loss of 10 velocity heads across the orifice. (Density of the dichlorobenzene 1300 kg/m3, viscosity 1.4 cp).

The surface casing of the well is to be cemented to the surface with a single-stage cementing using Class G cement + 5% bentonite. Estimate the total number of sacks required for cement & bentonite and total time required to seal surface casing with 20% excess of the total volume of slurry.

Additional information: The shoe track is 60 ft and has a rathole of 10ft. 15 minutes required to release the plugs with 15 sacks/min of mixing rate and 250 gal/min of pumping rate.

The surface casing of the well is to be cemented to the surface with a single-stage cementing using Class G cement + 5% bentonite. Estimate the total number of sacks required for cement & bentonite and total time required to seal surface casing with 20% excess of the total volume of slurry. 

agent orange contains about 2 ppm (m/v) of dioxin, a very toxic substance, as an impurity. how many milliliters of agent orange would have to be used in order to place 0.01 g of dioxin in the environment

0.15 gm of calcium carbonate is dissolved in 1 liter of distilled water. 20 ml of this

standard hard water requires 25 ml of EDTA solution. 100 ml of unknown hard water requires 18 ml of EDTA solution. The same water sample after boiling requires 12 ml of EDTA solution. Calculate Temporary hardness of water sample in ppm.

Standard hard water is prepared by dissolving 0.28 gm of calcium carbonate in dilute HCI

and then diluted to 1 liter with distilled water. 100 ml of this standard hard water requires 28 ml of EDTA solution. 100 ml of unknown hard water requires 33 ml of EDTA solution. 100 ml of same water sample after boiling requires 10 ml of EDTA solution. Calculate Total, Permanent and Temporary hardness of water sample

0.45 gm of calcium carbonate is dissolved in 1 liter of distilled water. 50 ml of this

standard hard water requires 20 ml of EDTA solution. 50 ml of unknown hard water requires 12 ml of EDTA solution. 50 ml of same water sample after boiling requires 8 ml of EDTA solution. Calculate Total, Permanent and Temporary hardness of water sample

1 gm of calcium carbonate is dissolved in dilute HCl and diluted to 1 liter with distilled

water. 100 ml of this standard hard water requires 90 ml of EDTA solution. 100 ml of unknown hard water requires 36 ml of EDTA solution. 100 ml of same water sample after boiling requires 18 ml of EDTA solution. Calculate Carbonate and Non-carbonate hardness of water sample.

0.75 gm of calcium carbonate is dissolved in 1 liter of distilled water. 100 ml of this

standard hard water requires 25 ml of EDTA solution. 100 ml of unknown hard water requires 15 ml of EDTA solution. 100 ml of same water sample after boiling requires 10 ml of EDTA solution. Calculate Total, Permanent and Temporary hardness of water sample.