Steam condensation process

Although highly effective, this conventional carbon bed adsorption technique does have an inherent enviromnental drawback. By-product water resulting from the steam condensation process is likely to be contaminated. In effect, an air quality control problem may be corrected, but a water quality control problem may be created. 

From steam tables, the outlet temperature is 251°C, which is superheated by 67°C. Although steam for process heating is preferred at saturated conditions, it is not desirable in this case to desuperheat by boiler feedwater injection to bring to saturated conditions. If saturated steam is fed to the main, then the heat losses from the main will cause a large amount of condensation in the main, which is undesirable. Hence it is better to feed steam to the main with some superheat to avoid condensation in the main. 

During this process some water will have condensed in the steam-trap D and also in the distillation bulb F. If at the end of the steaming-out process, the Bunsen burner is removed from the generator A, the pressure in A will be reduced owing to steam condensation, and the liquid in F will be sucked back into D provided that the benL-over tube is carefully adjusted, the bulb F may be almost completely emptied of liquid as desired. Finally the condensed water in the steam-trap D may be run out by op ing the tap Tj. 

Product warehouse(s) Process pipe hues—steam, condensate, water, gas, fuel oil, air, fire, instru-... 

Condensation is the process of reduction of matter into a denser form, as in the liquefaction of vapor or steam. Condensation is the result of the reduction of temperature by the removal of the latent heat of evaporation. The removal of heat shrinks the volume of the vapor and decreases the velocity of, and the distance between, molecules. The process can also be thought of as a reaction involving the union of atoms in molecules. The process often leads to the elimination of a simple molecule to form a new and more complex compound. 

If the mixture is separated by a continuous flash process and the components are considered insoluble in water (check references) and the feed enters at the flash chamber at 20°C, calculate the mols of steam condensed, the total mols steam required per 100 mols of feed, and... 

Figure 10-177. Air-cooled Stac-Flo steam condensers illustrating process system. Representative types of tubes are illustrated. (Used by permission Bui. M-390621 10/90. Hudson Products Corporation)...

Christman, J., Vacuum Steam Condensers Air vs. Water Cooling, Hydrocarbon Processing, Sept. (1980) p. 257. 

From Figure 26.7 it can be seen that for equal duties and flows the temperature difference for countercurrent flow is lower at the steam inlet than at the outlet, with most of the steam condensation taking place in the lower half of the plate. The reverse holds tme for co-current flow. In this case, most of the steam condenses in the top half of the plate, the mean vapor velocity is lower and a reduction in pressure drop of between 10-40 per cent occurs. This difference in pressure drop becomes lower for duties where the final approach temperature between the steam and process fluid becomes larger. 

Where steam is used for sterilization, hospital duty, food and drug manufacturing processes, or steam humidification purposes, there generally is a reluctance (or mandated prohibition) to employ amines as a treatment for steam-condensate line corrosion protection. Clean-steam... 

NOTE Oil and process contaminants may lead to steam-condensate system deposit problems in a fashion similar to entrainment. 

Increased demand for softened MU, perhaps caused by an increase in plant capacity without increasing softener capacity installed, or the use of additional steam for processing so that the return of condensate is diminished. Here a larger plant is required. If the existing plant is not too old, a second identical unit usually is installed and the equipment is operated as duty/standby, with water-meter countdown crossover and immediate regeneration of the out-of-service unit. 

Where problems develop, there is always a cause-and-effect process. In this case, as oxygen infiltrates the CR system, enhanced condensate line corrosion results (i.e., corrosion over and above the level that may be caused by the carbonic acid formed during steam condensation). This enhanced corrosion, in turn, creates the potential for further downstream corrosion debris pickup by the returning condensate and transporting this material back to the FW system. 

Process leaks from food and beverage production or wood leachates often produce sugars, colloidal materials, pectins, emulsions, and proteins that cause stable foams in the boiler. These lead to carryover and further steam-condensate line contamination. The temporary use of a demulsifier or defoamer as part of the water treatment program may be of particular benefit, but again the condensate is unsuitable for return to the boiler. Other process leaks include ... 

In large and extensive industrial process plants, it is not unusual to find unvented condensate receivers or reboilers at the end of a long steam-condensate line. These vessels tend to act as collection and storage points for carbon dioxide, which may redissolve in condensate. These satellite stations should be vented and receive an amine booster feed. 

In certain direct steam-contact process applications (such as in food and beverage processing or pharmaceutical preparations) the use of amine-based products in steam and condensate systems is subject to legal restrictions. Also, the use of ammonia or amines may be dependent on the materials of construction employed or technical limitations (such as the risk of copper alloy corrosion). 

The temperature at which water vapor (steam) condenses. The dewpoint temperature is important in boiler fuel combustion processes, as whenever a metal surface is cooler than flue gas, condensation occurs. If sulfur gases are present and the acid dewpoint (the tem-... 

This does not need to be corrected using Equation 15.102 as the steam condensing film coefficient and process fouling coefficient agree with the assumptions on which the correlation is based. 

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