Steam vapor distribution

Vapor distributors ensure a smooth vapor distribution before the vapor enters the packed bed. They fall into two classes. The first class consists of those that distribute the vapor fiow profile by imposing a pressure drop on the vapor steam. The second class consists of devices that mechanically redistribute the vapor flow by means of vanes. 

A.mmonium C/j/oride. Work on the distribution of ammonium chloride [12125-02-9] between the vapor andhquid phases (8) suggests that the Ray diagram is sometimes an oversimplification. In most steam systems, there is much more ammonia than any other impurity. In particular, there is more ammonia than hydrogen chloride. The volatiUty of ammonium chloride is therefore expressed by the following chemical equation ... 

Dukler Theory The preceding expressions for condensation are based on the classical Nusselt theoiy. It is generally known and conceded that the film coefficients for steam and organic vapors calculated by the Nusselt theory are conservatively low. Dukler [Chem. Eng. Prog., 55, 62 (1959)] developed equations for velocity and temperature distribution in thin films on vertical walls based on expressions of Deissler (NACA Tech. Notes 2129, 1950 2138, 1952 3145, 1959) for the eddy viscosity and thermal conductivity near the solid boundaiy. According to the Dukler theoiy, three fixed factors must be known to estabhsh the value of the average film coefficient the terminal Reynolds number, the Prandtl number of the condensed phase, and a dimensionless group defined as follows ... 

The compressors to be covered in this book are those using mechanical motion to effect the compression. These types of compressors are commonly used in the process and gas transport/distribution industries. A partial list of these industries includes chemical, petrochemical, refinery, pulp and paper, and utilities. A few typical applications are air separation, vapor extraction, refrigeration, steam recompression, process and plant air. 

Figure 13. Steam outside tube evaporator (A) Shell (B) Tube sheets (C CJ Distributing plates (D) Vapor head (E) Baffles (F) Steam inlet (G) Condensate outlet (H) Non-condensed gas vent (J) Thick liquor outlet (K) Vapor outlet (L) Liquor feed box.

Heavy cycle oil, heavy naphtha, and other circulating side pumparound reflux streams are used to remove heat from the fractionator. They supply reboil heat to the gas plant and generate steam. The amount of heat removed at any pumparound point is set to distribute vapor and liquid loads evenly throughout the column and to provide the necessary internal reflux. 

Distribution Ratio (DR) The DR relates the concentration of an amine present in the steam phase to that concentration in the condensate phase (vapor-liquid distribution ratio). Consequently, it identifies in which condensate production region of a steam-condensate system any particular amine will concentrate and thus provide protection against corrosion. It also helps to indicates the portion of amine loss due to vaporization in a condenser or venting of a deaerator. The expression for DR is shown here ... 

Steam-liquid flow. Two-phase flow maps and heat transfer prediction methods which exist for vaporization in macro-channels and are inapplicable in micro-channels. Due to the predominance of surface tension over the gravity forces, the orientation of micro-channel has a negligible influence on the flow pattern. The models of convection boiling should correlate the frequencies, length and velocities of the bubbles and the coalescence processes, which control the flow pattern transitions, with the heat flux and the mass flux. The vapor bubble size distribution must be taken into account. 

A basic process flow diagram for the SNCR TDN process is shown in Figure 17.3. Anhydrous or aqueous ammonia is vaporized and mixed with a carrier gas of air or steam for transport to injection/distribution modules. The injection distribution modules distribute ammonia and/or hydrogen reagent and carrier gas to proprietary spray nozzles or injection lances. Reagent flow control can be controlled and trimmed by outlet NOx signals or ammonia slip measurements. 

IAPWS, Guideline on the Henry s Constant and Vapor-Liquid Distribution Constant for Gases in H20 and D20 at High Temperatures, The International Association for the Properties of Water and Steam, Kyoto, Japan (2004)... 

From this distribution of the stripping steam, we can conclude that the pounds of vapor to the bottom tray is much larger than the pounds of vapor leaving the top tray. This is just the opposite of the diesel-oil... 

Fluidized bed reactors typrcally are vertical cylindrical vessels equipped with a support grid and feed sparger system for adequate fluidization and feed distribution, internal cooling coils for heat removal, and either external or internal cyclones to minimize catalyst carryover. Fluidizauon of the catalyst assures intimate contact between feed and product vapors, catalyst, and heat-transfer surfaces, and results in a uniform temperature within the reactor. Reaction heat can be removed by generating steam within the cooling coils or by some oilier heat-transfer medium. 

A well-insulated tank of 70-tin3 volume initially contains 23,000 kg of water distributed between liquid and vapor phases at 25°C. Saturated steam at 1,100 kPa is admitted to the tank until the pressure... 

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