Stream number

It is not only the stream number that creates the need to split streams at the pinch. Sometimes the CP inequality criteria [Eqs. (16.1) and (16.2)] CEmnot be met at the pinch without a stream split. Consider the above-pinch part of a problem in Fig. 16.13a. The number of hot streams is less than the number of cold, and hence Eq. (16.3) is satisfied. However, the CP inequality also must be satisfied, i.e., Eq. (16.1). Neither of the two cold streams has a large enough CP. The hot stream can be made smaller by splitting it into two parallel branches (Fig. 16.136). 

Clearly, in designs different from those in Figs. 16.13 and 16.14 when streams are split to satisfy the CP inequality, this might create a problem with the number of streams at the pinch such that Eqs. (16.3) and (16.4) are no longer satisfied. This would then require further stream splits to satisfy the stream number criterion. Figure 16.15 presents algorithms for the overall approach. ... 

Figure 5.3-17. Flow-sheet of a batch process unit symbols E = heat exchanger, P = pump, R = reactor, T = storage tank, V = vessel controllers FC = flow controller, LC = level controller 0 stream number.

Stream number Type Heat capacity CP, kW/°C Ts °C T, °C Heat load kW... 

It is convenient to represent a heat exchanger network as a grid see Figure 3.24. The process streams are drawn as horizontal lines, with the stream numbers shown in square boxes. Hot streams are drawn at the top of the grid, and flow from left to right. The cold streams are drawn at the bottom, and flow from right to left. The stream heat capacities CP are shown in a column at the end of the stream lines. 

Stream Number of Samples Flow Range (m3/d) Flow Median (m3/d) Flow Mean (m3/d)... 

Stream number Limiting water flowrate (t-h 1) Cin (ppm) Cout (ppm) Contaminant mass flowrate (g-h 1)... 

Macroinvertebrate communities 11.3 pg/L for 10 days Abundance was reduced by 75% in laboratory studies vs. 44% in field experimental streams number of taxa was reduced 56% in the laboratory vs. 10% in field streams 76... 

Consider the process flowsheet shown in Figure El6.4, which was used by Rollins and Davis (1993) in investigations of gross error detection. The seven stream numbers are identified in Figure El6.4. The overall material balance can be expressed using the constraint matrix Ay = 0, where A is given by... 

Stream number True value (kg/min) Measured value (kg/min) Reconciled value (kg/min)... 

Now, consider the same system under a new arrangement of the measurements, as shown in Fig. 3. In this case, the flowrate of stream number 2 is considered measured. The matrices Ai and A2 are now... 

Stream Number Stream Source Liquid Flowrate (GPD) Arseni c Rate (Ib/MO) Percent Arsenic to HF Treatment System and Recycled Solids Total Arsenic Concentration (mg/L) Percent Solids Soluble Arsenic Concentration (mg/L)... 

Stream Number Temp °F Pressure psia Flow Rate — (—) day yday/ Mole Fraction ... 

The data and equations are entered into locations in the spread sheet as follows The first five rows are used for labels and constants the first column is used for labels and stream numbers. Each location that will contain a number is initialized to zero. The value 100, the carbon monoxide feed rate in mol/h,... 

Pure component physical property data for the five species in our simulation of the HDA process were obtained from Chemical Engineering (1975) (liquid densities, heat capacities, vapor pressures, etc.). Vapor-liquid equilibrium behavior was assumed to be ideal. Much of the flowsheet and equipment design information was extracted from Douglas (1988). We have also determined certain design and control variables (e.g., column feed locations, temperature control trays, overhead receiver and column base liquid holdups.) that are not specified by Douglas. Tables 10.1 to 10.4 contain data for selected process streams. These data come from our TMODS dynamic simulation and not from a commercial steady-state simulation package. The corresponding stream numbers are shown in Fig. 10.1. In our simulation, the stabilizer column is modeled as a component splitter and tank. A heater is used to raise the temperature of the liquid feed stream to the product column. Table 10.5 presents equipment data and Table 10.6 compiles the heat transfer rates within process equipment. 

Tables 11.5 to 11.7 contain process stream data. These data come from the TMODS dynamic simulation and not from a commercial steady-state simulation package. The corresponding stream numbers are shown on the flowsheet in Fig. 11.1. Tables 11.8 to 11.10 list the process equipment and vessel data. In the simulation, all gas is removed in a component separator prior to the distillation column. This involves the liquid from the separator and the absorber. The gas is sent back and combines with the vapor product from the separator to form the vapor feed to the absorber. Figure 11.2a shows the temperature profile in the azeotropic distillation column.

First Subscript - stream number Second Subscript... 

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