Liquid chemical feed calculator

Liquid chemical feed calculations are the subject of chapter 8. This chapter includes the calculations for dry chemical feed either directly into process water or first into dissolving or slurry tanks, and to prepare solution batches. All dry chemical feeders are calibrated as needed to ensure accurate delivery of the chemical. 

Chapter 8. Liquid Chemical Feed-Calculations and Examples 95... 

Gas Chemical Feed Calculators 135 Dry Chemical Feed Calculators 141 Liquid Chemical Feed Calculators 142... 

These types of liquid chemical feed systems use a second tank (dilution tank). Bulk storage tanks may be distant from the chemical feed pump location, there may be concerns about safety of the bulk chemical, or it may be necessary to dilute the chemical for accurate feed or to aid in mixing with process water. Whatever the reason, feed calculations are the same as those given for chemical feed of solutions calculators (c8-10 through c8-13). The only difference is that the percent solution strength is less than for bulk chemicals. 

Design a two-phase gas-liquid CSTR for the chlorination of benzene at 55°C by calculating the total volume that corresponds to an operating point where r/X = 500 on the horizontal axis of the CSTR performance curve in Figure 24-1. The time constant for convective mass transfer in the liquid phase is r. The time constant for second-order irreversible chemical reaction in the liquid phase is If the liquid benzene feed stream is diluted with an inert, then 7 increases. The liquid-phase volumetric flow rate is 5 gal/min. The inlet molar flow rate ratio of chlorine gas to liquid benzene... 

Some liquid chemicals are fed directly from the storage tank to the process water without any dilution. The chemicals may be delivered already diluted or may be 100 percent strength. Calculating the chemical feed rate requires knowing the process water flow rate, the applied dosage, and the solution strength. 

Calculators 8-1 and 8-2 (identical to dry feed calculators 6-1 and 6-2) can be used to determine the feed rate of pure chemical for a given dosage and flow rate. These are often used for liquid polymers (polyelectrolytes) where the polymer in the delivery drum is fed directly to the point of application without dilution. 

Example 8-1 Calculate the volume of liquid polymer needed to make 500 gal of a 1 percent solution used for chemical feed. The density of the original liquid polymer is 9.5 Ib/gal. 

COCURRENT FLOW OPERATION. When the chemical reaction is essentially irreversible and the equilibrium partial pressure of the solute is zero, the number of transfer units for a given separation is the same for countercurrent operation or for cocurrent flow of liquid and gas. Figure 22.24 shows typical operating lines for both cases. In this diagram x is the total solute absorbed and reacted and not the amount of solute present in the original form. For cocurrent operation with the feeds at the top, the gas leaving at the bottom is exposed to rich liquid, which has absorbed a lot of solute, but if jf = 0, the driving force is just y, and Noy is calculated from Eq. (22.50), as for countercurrent flow. 

If VLE data are available in equation form, spreadsheet calculations can also be used for multiconponent flash distillation. These calculations are illustrated for a chemical mixture that follows Eq. 12-161 for Problem 2.D16. First, the spreadsheet is shown in Figure 2-B3 with the equations in each cell. Cells B3 to B6, C3 to C6, D3 to D6, E3 to E6, F3 to F6, and G3 to G6 are the constants for Eq. (2-161 from Table 2-3. Conditions for the operation are input in cells B7, D7, and F7, and the feed mole fractions are in cells B8, C8, F8, and G9. Eq. 12-161 is programmed for each conponent in cells BIO, Bll, B12, and B13. Then the liquid mole fractions are determined fromEq. 12-381 in cells B15 to B18. These four numbers are summed in cell B19. The Rachford-Rice terms from Eq. 12-421 for each conponent are calculated in cells B20 to B23, and the sum is in B24. 

Let us now review reverse osmosis transport. Both feed and permeates are in the liquid phase, and we do not need to convert the concentration to partial vapor pressure to calculate the chemical potential difference as the driving force. Instead, Equations 5.241 and 5.242 are used as given. Let us define component B as the solvent and component A as the solute. Then Equations 5.242 and 5.241 can be written as... 

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