Material balance production

The reaction in terms of A and B is 4A + 6B —> products. Material balance of species A gives... 

The conversions are approximations, based on the detection of unconverted reactants in the products. Material balances are not well known. 

Chemostat with Empirical Kinetics Using the CSTR equation (7-54) for a constant-volume single reaction [Eq. (7-147)], the substrate, biomass, and product material balances are... 

For both polymerization and rubber processing it is important to know the type and amount of unsaturation. In this connection IR spectroscopy is perhaps the most useful technique, although it requires a preliminary evaluation of band absorptivities by means of suitable standards, analyzed by an independent technique. A number of methods are available to analyze these standards NMR spectroscopy, the iodine-monochloride method, gas-chromatographic analysis of pyrolysis products, materials balance determination, etc.12 Provided the termo-nomer content of the standard is not too low, the most useful technique is NMR, based on the ratio between the signal from all saturated protons (generally with chemical shifts of 2S from TMS) and the signal from olefinic protons, observed at lower fields (45-5.5 5). 

Keywords compressibility, primary-, secondary- and enhanced oil-recovery, drive mechanisms (solution gas-, gas cap-, water-drive), secondary gas cap, first production date, build-up period, plateau period, production decline, water cut, Darcy s law, recovery factor, sweep efficiency, by-passing of oil, residual oil, relative permeability, production forecasts, offtake rate, coning, cusping, horizontal wells, reservoir simulation, material balance, rate dependent processes, pre-drilling. 

Reservoir engineers describe the relationship between the volume of fluids produced, the compressibility of the fluids and the reservoir pressure using material balance techniques. This approach treats the reservoir system like a tank, filled with oil, water, gas, and reservoir rock in the appropriate volumes, but without regard to the distribution of the fluids (i.e. the detailed movement of fluids inside the system). Material balance uses the PVT properties of the fluids described in Section 5.2.6, and accounts for the variations of fluid properties with pressure. The technique is firstly useful in predicting how reservoir pressure will respond to production. Secondly, material balance can be used to reduce uncertainty in volumetries by measuring reservoir pressure and cumulative production during the producing phase of the field life. An example of the simplest material balance equation for an oil reservoir above the bubble point will be shown In the next section. 

It is possible that more than one of these drive mechanisms occur simultaneously the most common combination being gas cap drive and natural aquifer drive. Material balance techniques are applied to historic production data to estimate the contribution from each drive mechanism. 

The primary drive mechanism for gas field production is the expansion of the gas contained in the reservoir. Relative to oil reservoirs, the material balance calculations for gas reservoirs is rather simple the recovery factor is linked to the drop in reservoir pressure in an almost linear manner. The non-linearity is due to the changing z-factor (introduced in Section 5.2.4) as the pressure drops. A plot of (P/ z) against the recovery factor is linear if aquifer influx and pore compaction are negligible. The material balance may therefore be represented by the following plot (often called the P over z plot). 

Current Efficiency. Current efficiency for caustic production in diaphragm and membrane cells can be estimated from collection of a known amount of caustic over a period of time and from a knowledge of the number of coulombs of electricity passed during that time period. An alternative method involves analysis of the gases evolved during electrolysis and determining the anolyte composition. Material balance considerations (7) show the expression for the caustic efficiency for membrane cells to be... 

In a typical balanced plant producing vinyl chloride from EDC, all the HCl produced in EDC pyrolysis is used as the feed for oxychlorination. On this basis, EDC production is about evenly spHt between direct chlorination and oxychlorination, and there is no net production or consumption of HCl. The three principal operating steps used in the balanced process for ethylene-based vinyl chloride production are shown in the block flow diagram in Eigure 1, and a schematic of the overall process for a conventional plant is shown in Eigure 2 (76). A typical material balance for this process is given in Table 2. 

Table 2. Typical Material Balance for Vinyl Chloride Production by the Air-Based Balanced Ethylene Process...

The most impoi tant factor affecting product quahty is the material balance. In separating a feed stream F into distillate D and bottom B products, an overall mole-flow balance must be maintained ... 

Raw Materials The cost of raw materials is normally the largest item of expense in the manufacturing cost of a product. The quantities of raw materials consumed can be c culated from material balances. 

FIG. 13-29 Material-balance envelope which contains two external streams D and S, where S represents a sidestream product withdrawn above the feed plate,... 

It has been suggested that the circulating load can be calculated by a material balance from size analyses of the feed, fine product, and coarse product of the classifier in a closed-circuit grinding system [Bond, Rock Prod., 41, 64 (January 1938)]. However, since size analyses are subject to error, it is better to use this information to check the size analyses (Vaillant, op. cit.). The appropriate equation is (Dahl, Classifier Test Manual, Portland Cem. Assoc. BuU. MRB-53, 1954)... 

Reports listing of necessary reports for example, production status inventories of supplied materials and product, mass balances... 

Only parts needed above but for the vapor-phase reactor are listed here. Most of the description for the installation for methanol synthesis experiments (Figure 4.2.1) holds for this installation, too. In the mentioned unit, product was blown down while still hot, thus keeping all product in a single vapor phase. This simplifies material balance calculations. When avoiding condensation is difficult, cooling and separation becomes necessary. This method was used in the cited AIChEJ publication. 

A VCM (vinyl chloride monomer) production unit uses three vertically mounted agitated reactors for the polymerization of vinyl chloride. Crude material balances infer about 8 to 10% monomer losses. Describe how you would go about assessing whether these losses are due to leaks such as fugitive air emissions. Be specific in recommending procedures and instruments. 

Step 7 Write an Overall Material Balance. Remember that the P2 audit focuses on a unit process, but that there are individual unit operations that make up this process. The team will need to develop a series of material balances for each unit operation, and an overall material balance about the entire unit process, to bring closure to a solution of parameters of interest. The individual or component material balances developed may be summed to give a balance for the whole process, production area, or factory. 

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