Liquid-water requirement

There are not many models that do transients, mainly because of the computational cost and complexity. The models that do have mainly been discussed above. In terms of modeling, the equations use the time derivatives in the conservation equations (eqs 23 and 68) and there is still no accumulation of current or charging of the double layer that is, eq 27 still holds. The mass balance for liquid water requires that the saturation enter into the time derivative because it is the change in the water loading per unit time. However, this treatment is not necessarily rigorous because a water capacitance term should also be included,although it can be neglected as a first approximation. 

Figure 23.2 shows Fig. 23.1 s acid plant liquid water requirement as a function of vol-ume% H20(g) in its moist input gas. As expected, water requirement falls with increasing H20(g) in moist feed gas. 

Figure 23.3 shows the Fig. 23.1 acid plant s liquid water requirement as a function of specified mass% H2SO4 in product acid (constant volume% H20(g) in moist acid plant input gas). Water requirement increases with decreasing mass% H2SO4 in acid (i.e., with increasing specified mass% H2O in acid). 

Dry first catalyst bed feed gas SO2 concentration is used to determine the mass SO3 entering the absorption tower using Eq. 23.10 and the specification that 98% of the dry first catalyst bed feed gas SO2 is oxidized to SO3 before entering the absorption tower. The matrix in Table 23.1 is then used to determine the liquid water requirement at the specified product acid concentration and mass SO3 entering the absorption tower. 

Figure 23.4 Figure 23.1 acid plant liquid water requirement as a function of mass% H2SO4 in acid plant product acid and varying first catalyst bed dry feed gas SO2 concentration. Higher mass% H2SO4 acid is produced with higher feed gas SO2 concentration gas with constant feed gas moisture content (5 volume% H2O). 

An adequate prediction of multicomponent vapor-liquid equilibria requires an accurate description of the phase equilibria for the binary systems. We have reduced a large body of binary data including a variety of systems containing, for example, alcohols, ethers, ketones, organic acids, water, and hydrocarbons with the UNIQUAC equation. Experience has shown it to do as well as any of the other common models. V7hen all types of mixtures are considered, including partially miscible systems, the... 

ITi = weight in air of the water required to fill the pyknometer at fC W2 = weight in air of the liquid required to fill the pyknometer at t°C d = density of water in grams per milliliter at fC Sync = specific gravity of the liquid at t°C referred to water at t°C corrected for the buoyant effect of air... 

Elevated pressures are required to keep water in the Hquid state. Liquid water cataly2es oxidation so that reactions proceed at relatively lower temperatures than would be required if the same materials were oxidi2ed in open flame combustion. At the same time, water moderates oxidation rates by providing a medium for heat transfer and removing excess heat by evaporation. 

Minimum Wetting Rate The minimum liquid rate required for complete wetting of a vertical surface is about 0.03 to 0.3 kg/m s for water at room temperature. The minimum rate depends on the geom-etiy and nature of the vertical surface, liquid surface tension, and mass transfer between surrounding gas and the liquid. See Ponter, et al. Int. J. Heat Mass Tran.fer 10, 349-359 [1967] Trans. Inst. Chem. Eng. [London], 45, 345—352 [1967]), Stainthorp and Allen Trans. Inst. Chem. Eng. [London], 43, 85-91 [1967]) and Watanabe, et al. ]. Chem. Eng. [Japan], 8[1], 75 [1975]). 

Stripping Air stripping is applied for the removal of volatile substances from water. Henry s law is the key relationship for use in design of stripping systems. The minimum gas-to-liquid ratio required for stripping is given by ... 

In determining the proper size and number of cyclones required for a given application, two main objectives must be considered. The first is the classification or separation that is required, and the second is the volume of feed slurry to be handled. In the case of hydroclones, before determining whether these objectives can be achieved, it is necessary to establish a base condition as follows Feed liquid - water at 20 C. Feed solids - spherical particles of 2.65 specific gravity Feed concentration - less than 1 % solids by volume Pressure drop - 69 kPa (10 psi) Cyclone geometry - "standard cyclone" as described above. 

The liquid is the more dense phase (Figure 9.7b). The liquid-solid line is inclined to the left, toward the y-axis. An increase in pressure favors the formation of liquid that is, the melting point is decreased by raising the pressure. Water is one of the few substances that behave this way ice is less dense than liquid water. The effect is exaggerated for emphasis in Figure 9.7b. Actually, an increase in pressure of 134 atm is required to lower the melting point of ice by 1°C. 

Aluminum sulfate generally produces a large sludge volume and is slow to react and often difficult to de-water. It is usually supplied in dry blocks or a = 50% strength liquid. The required dose rate varies considerably, but it is approximately 20 to 100 ppm, as supplied. 

A venturi meter with a 50 mm throat is used to measure a flow of slightly salty water in a pipe of inside diameter 100 mm. The meter is checked by adding 20 cm3/s of normal sodium chloride solution above the meter and analysing a sample of water downstream from the meter. Before addition of the salt, 1000 cm- of water requires 10 cm3 of 0.1 M silver nitrate solution in a titration. 1000 cm3 of the downstream sample required 23.5 cm3 of 0.1 M silver nitrate. If a mercury-under-water manometer connected to the meter gives a reading of 20S mm, what is the discharge coefficient of the meter Assume that the density of the liquid is not appreciably affected by the salt. 

Heat capacity is an extensive property the larger the sample, the more heat is required to raise its temperature by a given amount and so the greater is its heat capacity (Fig. 6.10). It is therefore common to report either the specific heat capacity (often called just specific heat ), Cs, which is the heat capacity divided by the mass of the sample (Cs = dm), or the molar heat capacity, Cm, the heat capacity divided by the amount (in moles) of the sample (Cm = C/n). For example, the specific heat capacity of liquid water at room temperature is 4.18 J-(°C) -g, or 4.18 J-K 1-g and its molar heat capacity is 75 J-K -mol1. 

He placed two 150.-g samples of water at 0.00°C (one ice and one liquid) in a room kept at a constant temperature of 5.00°C. He then observed how long it took for each sample to warm to its final temperature. The liquid sample reached 5.00°C after 30.0 min. However, the ice took 10.5 h to reach 5.00°C. He concluded that the difference in time that the two samples required to reach the same final temperature represented the difference in heat required to raise the temperatures of the samples. Use Black s data to calculate the enthalpy of fusion of ice in kj-mol-1. Use the known heat capacity of liquid water. 

Condensed phase interactions can be divided roughly into two further categories chemical and physical. The latter involves all purely physical processes such as condensation of species of low volatility onto the surfaces of aerosol particles, adsorption, and absorption into liquid cloud and rainwater. Here, the interactions may be quite complex. For example, cloud droplets require a CCN, which in many instances is a particle of sulfate produced from SO2 and gas-particle conversion. If this particle is strongly acidic (as is often the case) HNO3 will not deposit on the aerosol particle rather, it will be dissolved in liquid water in clouds and rain. Thus, even though HNO3 is not very soluble in... 

---