Entrainment estimation

Figure 15 illustrates sand entrainment on the original cold flow rig. While the trend for sand entrainment estimated from the CFD calculations is correct, on a quantitative basis the under-prediction is significant, namely by a factor of up to three for the lower superficial velocities. The main source of error is the entrainment mechanism. 

Produced from Co l. Estimates of the cost of producing methanol from coal have been made by the U.S. Department of Energy (DOE) (12,17) and they are more uncertain than those using natural gas. Experience in coal-to-methanol faciUties of the type and size that would offer the most competitive product is limited. The projected costs of coal-derived methanol are considerably higher than those of methanol produced from natural gas. The cost of the production faciUty accounts for most of the increase (11). Coal-derived methanol is not expected to compete with gasoline unless oil prices exceed 0.31/L ( 50/bbl). Successful development of lower cost entrained gasification technologies could reduce the cost so as to make coal-derived methanol competitive at oil prices as low as 0.25/L ( 40/bbl) (17) (see Coal conversion processes). 

CASRAM predicts discharge fractions, flash-entrainment quantities, and liquid pool evaporation rates used as input to the model s dispersion algorithm to estimate chemical hazard population exposure zones. The output of CASRAM is a deterministic estimate of the hazard zone (to estimate an associated population health risk value) or the probability distributions of hazard-zones (which is used to estimate an associated distribution population health risk). 

The coefficients in the equations differ slightly in different references, depending on the entrainment coefficients used. The convective heat flux , in W or W/m from the heat source, can be estimated from the energy consumption of the heat source by... 

I he capture efficiency of an existing enclosure installation Can be estimated by measuring the portions of captured and spilled dust. The measurement program can be quite involved depending on enclosure size, intermittence of operation, dust settlement in the enclosure, and the extent of air entrainment. The measurement program must be custom designed to best suit the operation. ... 

Entrainment is an important element in the mixing operation and involves incorporation of low velocity fluid into the mass of the fluid stream or jet issuing from a source such as a mixing impeller. The axial flow from a propeller under proper physical conditions serves as a circular cross-section jet to produce mixing by turbulence and entrainment. The flat-blade turbine issues a jet for entrainment at the top and bottom, areas of the ring [2]. It is significant to estimate the relative amount of liquid involved due to entrainment, as this helps to describe the effectiveness of the operation. 

The work of Simkin, Strand, and Olney [64] correlates most of the work of other investigators, and can be used for estimation of probable entrainment from bubble cap trays as shown in Figure 8-116. It is recommended that the liquid entrainment for design be limited to 0.10 mols/mol dry vapor. 

Use with Figure 8-137 to estimate both flood point and entrainment. 

Figure 8-137 is used for estimating the entrainment-flood point. Liquid particle entrainment is generally considered as reducing tray efficiency (performance). 

Figure 8-138 [183] represents the final entrainment correlation used for estimating, thus, based on published data ... 

DL = drift loss, water lost from tower system entrained in exhaust air stream, measured as (a) % of circulating water rate, gpm, or (b) more precise [144], an L/G parameter and drift becomes pounds of water per million pounds of exhaust air for estimating ... 

The principal factor that determines the column diameter is the vapour flow-rate. The vapour velocity must be below that which would cause excessive liquid entrainment or a high-pressure drop. The equation given below, which is based on the well-known Souders and Brown equation, Lowenstein (1961), can be used to estimate the maximum allowable superficial vapour velocity, and hence the column area and diameter,... 

Entrainment can be estimated from the correlation given by Fair (1961), Figure 11.29, which gives the fractional entrainment tfr (kg/kg gross liquid flow) as a function of the liquid-vapour factor Fiv, with the percentage approach to flooding as a parameter. 

The effect of entrainment on plate efficiency can be estimated using equation 11.78. 

Economically, the elimination of lead and nickel emissions will result in an improved product because exposure of the metal to combustion gases in the current process results in porosity and entrainment of hydrogen gas in the metal. Overall, AMPCO estimates an annual savings in operations and maintenance expenses of USD 1.2 million with the use of this technology. Assuming the same 70% industry adoption, economic savings by 2010 could reach USD 5.8 million. Without the new electric induction heating process, the capital costs required for compliance could be USD 3 million. 

This section is a continuation of Section 21.3.2 dealing with pressure drop (-AP) for flow through a fixed bed of solid particles. Here, we make further use of the Ergun equation for estimating the minimum superficial fluidization velocity, ump In addition, by analogous treatment for free fall of a single particle, we develop a means for estimating terminal velocity, ur as a quantity related to elutriation and entrainment. 

The most important transformation process for di-w-octylphthalate present in the atmosphere as an aerosol is reaction with photochemically produced hydroxyl radicals. The half-life for this reaction has been estimated to be 4.5 14.8 hours (Howard et al. 1991). Actual atmospheric half-lives may be longer since phthalate esters sorbed to wind-entrained particulates may have long atmospheric residence times (Vista Chemical 1992). Direct photolysis in the atmosphere is not expected to be an important process (EPA 1993a HSDB 1995). 

The product yield from an entrainer-sublimation process may be estimated as follows. The mass flowrate G of the inert gas and the mass sublimation rate S are related by ... 

Hydrothermal venting injects fluids into seawater as buoyant, jetlike pliunes. These turbulent flows mix rapidly with seawater becoming diluted by factors of lO" to 10. This mixing eventually makes the plumes neutrally buoyant, after which they are transported laterally through the ocean basins as part of the intermediate and deepwater currents. Hydrothermal plumes have the potential to greatly affect seawater chemistry. From global estimates of hydrothermal fluid emissions and dilution ratios, a volume of seawater equivalent to the entire ocean can be entrained in the hydrothermal plumes every few thousand years. 

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