Overall Process Mass Balance

REACTION CAS BLEACH CAS REACTION CAS ADDED VATER TAIL CAS  

REACTION CAS VEAIC ACID REACTION GAS RED PRODUCT PRODUCT ACID 

A refrigeration unit is required for the cooling of plant make-up water and also for cooling the absorption tower cooling water. The cooling duty required from the refrigeration unit is estimated to be 325 kl/V. 

The air-feed compressor is a dual-stage unit with a calculated duty of 3 MW. Compressor shaft power is provided by tail-gas expansion (80% of required power) and a steam turbine. 

Nitrogen oxides dissolved in red product acid are stripped from the acid using a secondary air stream. This secondary air is recycled back into the oxidation unit, where the additional oxygen produces an extra 40% oxidation in the main reaction stream. 

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Overall process mass balance (see typical data for CM AOS production in Figure 5.26)... 

Ballestra conclude that the 1,4-dioxane content increases dramatically with a slight excess of the SOs/organic mole ratio in each reactor tube and any part of each reactor tube and in the overall process mass balance. Furthermore, 1,4-dioxane levels are affected by the type of base alcohol, the range of ethoxylation and the moisture content in the feedstock. The 1,4-dioxane content in alcohol ethoxylate sulphates in the range with 2-3 EO molecules, can nowadays be... 

A common altemative used where possible is the diafUtration mode with a crossflow UF membrane unit and concentrate recycle (Figure 7.2.5(e)). Here the solution concentration and viscosity are not allowed to increase due to the continuous addition of buffer replacing the permeate volume lost Equations developed in Section 6.4.2.1 for well-stirred UF cells having continuous diafUtration may be used here with appropriate care since we can treat the crossflow UF device as a blackbox far the purpose of an overall process mass balance and solute selectivity analysis. Similarly, the equations developed in Section 6.4.2.1 for a batch concentration process may be utilized here to determine various quantities, such as the yield of macrosolute, retentate concentration, etc. 

Students frequently have difficulty when they first encounter the concept of recycle because they find it hard to understand that material can circulate in a system without an accumulation of mass. If you have this difficulty, you might find it helpful to refer back to the flowchart of Figure 4.5-1. Observe that even though there is material circulating within the system, there is no net accumulation 110 kg of material enters the system each minute, and the same mass leaves each minute. Within the system there is a net circulation rate of 120 kg/min, but the circulation has no effect on the overall process material balance. 

General Material Balances. According to the law of conservation of mass, the total mass of an isolated system is invariant, even in the presence of chemical reactions. Thus, an overall material balance refers to a mass balance performed on the entire material (or contents) of the system. Instead, if a mass balance is made on any component (chemical compound or atomic species) involved in the process, it is termed a component (or species) material balance. The general mass balance equation has the following form, and it can be applied on any material in any process. 

The mass balance of the processes (Figure 5.4) shows that the catalytic procedure (Scheme 5.2a) is much more resource efficient than the stoichiometric conversion (Scheme 5.2b). As expected, integrating the synthesis of the iridium catalyst results in an increase of the overall waste production (compare (a) II and (a) III, Figure 5.4). 

If one considers the overall CTL process, considering the input to and outputs from the process, the overall mass balance for the system can be written as follows ... 

Thus, by considering the overall mass balance, i.e., looking at the inputs and outputs of the process, one can gain many insights into a process and also identify opportunities for C02 emissions reduction and enhancing feedstock utilization. 

At this point, the student reviewed the check clearing process in detail. Checks are issued to a supplier and an encumbrance is placed on an internal account in the chemical company the supplier cashes the check at the supplier s bank the check proceeds through a series of intermediate banks until it arrives at the chemical company s bank the issued amount is removed from the chemical company s bank account (cleared) and the check is then returned to the chemical company where the encumbrance on the internal account is removed. The system must achieve an overall mass balance such that the total or cumulative amount of money issued must eventually equal the total or cumulative amount of money cleared. 

The majority of composite fabrication processes are carried out with thermosetting resins. One must therefore keep track of both the cured and uncured resin. In what follows, first the overall mass balance equation for the resin phase will be developed, then a balance equation for the cured portion of the resin will be presented. 

Since the fiber phase is not stationary, the surface integral cannot be set to zero without further considerations. As shown earlier, dBr/dt = 1/V js Ur hids (see Eq. 5.10). Because der/dt = 0 in the IP process, the contribution of the surface integral to the overall mass balance is negligible. Based on this observation Equation 5.50 can be simplified mid the appropriate equation for a conservation of mass in this process can be obtained (i.e., V Ur) = 0). Using this, Equation 5.18 can be simplified and the appropriate species balance equation for the IP process can be obtained. This equation is similar to the equation obtained for the RTM process. 

Model Equations to Describe Component Balances. The design of PVD reacting systems requires a set of model equations describing the component balances for the reacting species and an overall mass balance within the control volume of the surface reaction zone. Constitutive equations that describe the rate processes can then be used to obtain solutions to the model equations. Material-specific parameters may be estimated or obtained from the literature, collateral experiments, or numerical fits to experimental data. In any event, design-oriented solutions to the model equations can be obtained without recourse to equipment-specific fitting parameters. Thus translation of scale from laboratory apparatus to production-scale equipment is possible. 

Let us assume that the separation section does not allow reactants Aj to leave the process. Then, the overall mass balance can be written as ... 

Hence, with porous particles, surface interaction will predominantly occur when the polypeptide and protein adsorbates reach the internal surface of the particles, thus enabling the mass balance, rate-limiting steps, and the mass transfer coefficients to be quantitatively and independently described. If it is assumed that the pores of the porous HPLC particles are initially filled with buffer liquid before the adsorption process starts, then the overall mass balance for a polypeptide or protein in a finite bath is given by... 

Input-output analysis focuses on the overall structure of the flowsheet, and the recycle streams are not considered here in as much as they do not appear in the overall flow streams. Hence, this structure is essentially an overall mass balance for the entire process. A simplified representation of the input-output structure is shown in Fig 6.5. The main purpose of this analysis is to identify the amount of raw materials used, useful products, and waste formed. 

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