Nominal production rate

A common problem encountered in large chemical companies involves the distribution of a single product (30 manufactured at several plant locations. Generally, the product needs to be delivered to several customers located at various distances from each plant. It is, therefore, desirable to determine how much Y must be produced at each of m plants (Yv Y2,..., Ym) and how, for example, Ym should be allocated to each of n demand points (YmV Ym2,. Ymnl The cost-minimizing solution to this problem not only involves the transportation costs between each supply and demand point but also the production cost versus capacity curves for each plant. The individual plants probably vary with respect to their nominal production rate, and some plants may be more efficient than others, having been constructed at a later date. Both of these factors contribute to a unique functionality between production cost and production rate. Because of the particular distribution of transportation costs, it may be... 

At this point it is useful to introduce dimensionless variables. Thus, we choose as the reference value the flow rate of the feed stream at the nominal production rate, F and define the dimensionless flows ... 

Although a plant is usually designed for a nominal production rate, a design tolerance is always incorporated because the market conditions may require an increase or decrease from the current rate. The control system is then called to ensure a smooth and safe transition from the old to the new production level. This is known as material balance control, because its purpose is to direct the control action in such a way as to make the inflows equal to the outflows and achieve a new steady-state material balance for the plant. Let us now see how to design the material balance control system for the hydrodealkylation plant. 

Examine the development of a control structure for HDA plant discussed in Chapter 7. Supplementary data on design and steady state simulation are given in Case Study 1. The nominal production rate is 120 kmol/h benzene at a purity exceeding 99.8%. The feed streams are pure toluene and hydrogen. Production flexibility of 25% is required... 

Accuracies of the flow meters discussed herein are specified as either a percentage of the full-scale flow or as a percentage of the actual flow rate. It may be convenient in some appHcations to compare the potential inaccuracies in actual volumetric flow rates. For example, in reading two Hters per minute (LPM) on a flow meter rated for five LPM, the maximum error for a 1% of full-scale accuracy specification would be 0.01 x 5 = 0.05 LPM. If another flow meter of similar range, but having 1% of actual flow rate specification, were used, the maximum error would be 0.01 x 2 = 0.02 LPM. To minimize errors, meters having full-scale accuracy specifications are normally not used at the lower end of their range. Whenever possible, performance parameters should be assessed for the expected installation conditions, not the reference conditions that are the basis of nominal product performance specifications. 

Based on dry dust at 961 kg/m. Capacity depends on type of material and desired product (rates are average for nominal 1.3-cm peUets). 

Perhaps the simplest way to assess the reliability of a system is to count the active parts, flic 1C liability estimate is the product of the number of parts and some nominal failure rate for the parts. Ill the design phase, two competing designs may be compared on the basis of the numbei of parts but several cautions are in order. 

Operating costs are conveniently considered in two groups, fixed and variable costs those dependent on production rate and those that are independent of production rate. Operating costs can be further broken down into a number of key elements as indicated in Table 14.1, where estimation guidelines for continuous plant are also given [42]. Of critical interest in the present context is how these values vary between a batch and a continuous plant of nominally the same production rate. 

Separation trains. With a nominal peak production rate determined and a GOR known, a large latitude then exists in selecting the oil-gas separation train configuration. 

Crystal form Source Nominal purity (%) BET surface area (m2/g) H2 production rate ((gmole/h)... 

Figure 3.9 Closed-loop response for a 15% increase in production rate and 1.5% decrease of the product-purity setpoint, (a) Product composition and (b) reactor holdup and setpoint in the nominal case with no modeling errors.

Assumption 5.2. The net rates at which the components 1,..., C — 1 are separated from the recycle loop, as well as the nominal flow rate of the product stream, are of comparable magnitude. Also, from mass-balance considerations, they are of the same magnitude as the flow rate of the process feed stream ... 

Figures 7.23-7.27 show the closed-loop profiles for a 10% increase in the production rate at operating point I (attained by increasing Fo), and a decrease in the purity setpoint to Cb,Sp = 1.888 mol/1 - this reduction is necessary since the nominal purity is beyond the maximum attainable purity for the increased throughput. Although controller design was carried out to account for the inverse response exhibited by the system at operating points II and III, and in spite of the plant-model parameter mismatch, the proposed control structure clearly yields good performance at operating point I as well.

The start button is then pressed, the glycerine pipe is extended to the nitrator, glycerine and mixed acids begin to flow at the selected production rate between the nominal rate (100%) and reduced to 50%. 

The major technical factors in electrorefining are cathode purity, production rate, and specific energy consumption. These factors are influenced primarily by anode quality, electrolyte conditions, and cathode current density. The electrolysis is performed in a solution of copper sulfate and sulfuric acid with a nominal composition of40-45 g L-1 copper and 160-200 g L-1 sulfuric acid at 60-66 °C with a current... 

A quick scoping estimate of the size of an industrial spray dryer can be made on this basis. The required evaporation rate or product rate can be multiplied by the relevant ratio from the table to give the mass flow rate of the drying gas. The next step would be to calculate the size of a spray drying chamber to allow the drying gas at outlet conditions approximately 25 s of residence time. A cylindrical chamber with diameter D and height H equal to D and a 60° conical bottom has a nominal volume of... 

In the meantime, a reasonably fast radioactive decay makes a different technique for obtaining data on fjp feasible, even with rather low activities. One can measure the fraction r]c of the nuclei introduced into the IC column which survives at its exit. This principle can be used in on-line experiments with the nuclides which have mean lifetimes much less than the nominal duration of the run in practice, it means the range from seconds to hours. For a nuclide with the particular tx, two or more measurements at different temperatures must be done. At least one at a temperature when t -C tx to find the production rate of the detectable activity, as well as one when r c is of the order of lx and so the surviving fraction is in the range 0 < rf < 1. From the point of view of the statistics, most desirable is to aim at rjc near 0.5. Obviously, r = exp -t r/tx), hence ... 

The effects of perturbation of this type can be seen in the crystal size distribution for a period of 6 to 10 times the nominal retention period. For an ammonium sulfate crystallizer, for instance, operating at a retention time of 4h, the effects of an upset would not be fully dissipated until a period of 1-2 days had passed. Because of this fundamental characteristic, it is necessary that the control system of a crystallizer and the flow sheet be arranged in such a way that stable operations can be maintained for extended periods of time. Only small changes in production rate should be made within any operating shift. The following controls are typical of those required for most continuous crystallizers similar to that shown in Figure 5.16, however, no list of this type can be all inclusive. 

Pure A is fed to the reactor mth a nominal inlet pressure of 2.0 atm. The desired production rate per tube is 18.84 kg/hr of B. If you choose to operate above the nominal Met pressure, an additional compressor has to be installed upstream of the reactor. The existing tubes are 100cross-sectional area. The remaining A in the product stream must be separated in a second unit for recycle. For the separation unit to run efficiently, the conversion in the reactor must be at least 93% and the outlet pressure must be at least 1.5 atm. If the reactor effluent pressure is below 1.5 atm, an additional compressor must be installed downstream of theTeactor.- ... 

---