Water deaeration

Suspended inert gas bubbles, too small to be seen, seem to be present in some liquids in an as-received condition. These motes can also come into being if a liquid containing dissolved gases is heated. The evidence is clear that such motes have a strong effect on the nucleate-boiling curve. Pike and co-workers (PI) boiled tap water, deaerated water, and water which had been brought to equilibrium with bubbling air at various temperatures. It was found that an increase in air content causes an increase in h. Similar results are reported by McAdams (M4). 

The boiler feed water deaerator reduced oxygen content to less than 7 ppb by the use of exhaust steam (low pressure). This system operated at lower temperature (110°C), used lower-pressure steam (0.05-MPa gauge), and achieved the oxygen specification without the use of chemical reducing agents as compared to conventional thermal desorption in a packed tower (7). 

Although considerable studies on the use of centrifugal fields in chemical processing have been reported for lab- and pilot-scale operations, little information is public on scale-up criteria for either performance parameters or equipment design. Three examples of commercial use of centrifugal fields are available for review. These include liquid-liquid extraction, water deaeration, and reactive stripping for hypochlorous acid production. 

Zheng C, Guo K, Song Y, Zhou X, Ai D. Industrial practice of Higravitec in water deaeration. In Semel J, ed. 2nd International Conference on Process Intensification in Practice. London BHR Group, 1997 273-287. 

Cost of package boiler plants. Price includes complete boiler, feed-water deaerator, boiler feed pumps, chemical injection system, stack, and shop assembly labor. 

Breitschopf F, Brau W, Dittrich S, and Koukol R, A new kind of water deaeration based on hollow fiber membranes, Brauwelt... 

Fig. 1.7 Ranges of half-cell potentialsof some electrochemical reactionsof importance in corrosion. Vertical bars represent metal ion concentration of 1 molal (approximately 10%) down to 1 ppm. Dashed extensions may apply with precipitated and complexing species. The hydrogen and oxygen reactions depend on both pH and pressure of the gases. Values for the hydrogen are at one atmosphere pressure. Values for oxygen are for water in contact with air (aerated) giving 10 ppm dissolved oxygen and for water deaerated to 1 ppb dissolved oxygen.

Figure 13.30 is a flow sheet showing the main process equipment of the Savannah River GS plant and the principal process conditions as given by Bebbington and Thayer [B7]. The plant consists of 24 units of type shown, operated in parallel. Not shown in the figure are the feed-water deaerator, the tower to recover H2S from purge gas, and pumps for liquid. 

Example 2.14 Design of a Hollow-Fiber Boiler Feed Water Deaerator... 

Fig. 20.33 A typical water deaeration plant involving pasteurization. Equipment for producing chilled, carbonated, deaerated, pasteurized water for beer dilution after high gravity brewing. Alternative systems lead water to the spray chamber either at 15°C or at temperatures above 100°C. In these, the holding tube is omitted. The system with the highest temperature of water relies on flash action within the spray vessel which eliminates the need for vacuum. (Based on diagrams of APV Co., Crawley.)...

There are several types of water deaerator available. A simple form has water (often deionized) charged with nitrogen gas spraying into an... 

The majority of the volume of beer in the world is processed by filter aid filtration. This technology relies on adding powders to the beer that form a very porous bed when they impinge on the filter surface. This is achieved by slurrying the filter aid in water, deaeration and pumping the slurry into the beer. Thus the prefilter beer on reaching the filter surface encounters a fresh layer of filter aid as the bed develops. This prolongs the filtration mn. 

In this service, the Hql f 2 plastic Super Intalox packing is 2.8 ft at a liquid rate of 40 gpm/ft and a temperature of 68 F. The Hql value increases at lower water temperatures in the same manner as for water deaeration. Thus, Hql is 3.0 ft at 53°F and 3.2 ft at 41 °F at a liquid rate of 40 gpm/ft. The same investigators found that the height of a liquid phase transfer unit for CO2 stripping increased in a similar manner with liquid rate as for oxygen desorption [6]. At a liquid rate of 30 gpm/ft the Hql is 2.6 ft, while at a liquid rate of 53 gpm/ft the Hql is 3.0 ft for 2 plastic Super Intalox packing at a water temperature of 68°F. 

Design Theory, Simplified Design Procedures, Column Diameter Selection, Water Deaeration, Water Decarbonation, Ammonia Stripping, Amine Regeneration, Hot Carbonate Regeneration, Side Strippers, Example Problem, Notation, References... 

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