Waste water strippers

All the process water streams are collected, the entrained hydrocarbons decanted, and the water is sent to the waste water stripper. 

The waste water stripper is a small tank used to increase the temperature of the waste water to approximately 95°C to evaporate residual solvent prior to discharge to the plant sump. The water exiting the waste water stripper is typically less than 0.001% (w/w) solvent. The hot water exiting the waste water stripper is often interchanged with the cool water entering the waste water stripper for heat recovery. 

Recovery from Effluent Water. All condensed mixtures of steam and solvent vapors go to a common solvent-water separator (mentioned above), where solvent overflows the top and water syphons out the bottom. The water, still containing traces of solvent, passes through a steam-heated waste-water stripper, where live steam raises the water temperature well above the boiling point of the solvent, 85°C (185°F) for hexane, which boils at 68.9°C (156°F). The driven-off solvent... 

In a process simulation, they play a decisive role for the mass balance in a decanter, operating at = 50 °C, and in a waste water stripper, operating at 2 = 2.3 bar, corresponding to a temperature 1 2 = 125 C. The task of the stripper is to take the organic components overhead to simplify the biological waste water treatment. Check whether the parameters can be used in the process simulation. If not, replace them by appropriate ones. 

Cilastatin - a bulk active pharmaceutical. Merck Co produce an antibiotic Primaxin (cilastatin (22) + imipenem (6)). To produce cilastatin, a process using methylene chloride was used. Methylene chloride features on the US Toxic Release Inventory (TRI) and elimination of emissions from chemical processes has become a priority. Merck have developed a novel process avoiding the use of methylene chloride altogether [13]. The new process, which cost some US 34 million to implement, required a further expenditure of some US 5 million on a fume stripper and US 500 000 on a waste water stripper. However, they claim to have cut their total TRI air emissions by more than 160 tonnes, of which 150 tonnes would have been methylene chloride. Merck also claim that the economics of the new process saved some US 7.2 million during the second half of 1992 alone. 

Referring to Fig. 47.3, for many refinery operations, the circulating thermosyphon reboiler shown can be eliminated and replaced with the same quantity of stripping steam, thus further simplifying the design of your waste water stripper installation. 

For many waste water strippers used in refinery services, rapid rates of reboiler fouling are experienced, not due to corrosion, but as a consequence of heavy hydrocarbon sludge, that settles out in the bottom of the sour water stripper feed tank. In particular, slurry oil that is produced in a refinery catalytic cracking unit can accumulate in the stripper s feed tank. This slurry oil, being denser than water, settles out in the tank and eventually is drawn into the suction of the sour water stripper feed pump. The heavy hydrocarbon phase then accumulates in the stripper s reboiler, and with time and temperature fouls the reboiler s tubes. 

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