Design Code units

Eigures 10-lA-G and Table 10-1 from the Standards of Tubular Exchanger Manufacturers Association give the nomenclature of the basic types of units. Note the nomenclature type designation code letters immediately below each illustration. These codes are assembled from Table 10-1 and Eigures 10-lA-G. 

Develop a model for an industrial riser reactor FCC unit. Collect the necessary data and develop the MATLAB code needed to design the unit from your model. 

This chapter contains the specification for the steam superheater to achieve the required design. Aspects to be considered include the heat-transfer requirements from the unit, and the mechanical and construction aspects of the design. It is noted that the unit must conform to the appropriate design codes (Australian or equivalent). 

The tank is specified to have a capacity of 1950 m3. This figure is the sum of one week production of nitric acid (1500 m3) plus an extra 450 m3. This extra 450 m3 capacity will be the normal tank operating level and is available for product sales to external markets. This represents approximately 20 standard road-tanker loads. The dimensions of the tank represent a standard specification available through the Denver Company (United States). The tank internal diameter is 15.2 m and the tank height required is 10.7 m. The internal and external pressure loads require a wall, base and roof plate thickness of 16 mm (a standard plate thickness available through BHP, Australia) to meet the Australian design code for pressure vessels (AS1 210). This thickness gives a 100% safety factor over the maximum anticipated stresses. 

The American Society of Mechanical Engineers (ASME), was asked by the government to formulate a design code, and developed the famous Boiler and Pressure Vessel Code between 1911 and 1914 as a set of safety mles to address the serious problem of boiler explosions in the United States. Average steam pressure in those days had reached only about 300 PSI (20 bar). Europe and other parts of the world used the code as a basis for their own safety mles. 

The goal of a conceptual design for a continuous process is to select the process units and the interconnections between these units, identify the dominant design variables and estimate the optimum design conditions, and identify the process alternatives and find the best four or so alternatives. For batch processes, we must also decide which units should be batch and which should be continuous, whether or not some process operations should be carried out in the same process unit or separate units, whether or not parallel units should be used, and how much intermediate storage is required. Thus, batch processes require more decisions to fix the structure of the flowsheet (there are more alternatives to consider). Since there are many situations in which it must be decided whether to develop a batch or a continuous process, both procedures should be present in a general conceptual design code, whereas the current trend is to develop separate codes for batch processes. 

The 11-run design and resulting data are listed in Table 9. The first four runs are the imbedded 2 factorial points, the next four runs are the axial or star points, and the last three runs are the center points. The factor levels are listed in the actual units ( uncoded form) and in coded units. The value of a was set to 1 to minimize the number of factor levels required, instead of conducting a rotatable design... 

Table 5 Coded units of parameters and response obtained from 2 full factorial design.

To analyze the operational parameters used in the acrylic acid production process, a fractional factorial design of two-level (2 ) with two level of fractionation was used. In this experimental design, six variables (Si , Fi , Xj , Dp, D and L) were investigated in 16 runs. The values of such parameters are shown in Table 7, whereas Table 8 depicts the coded units of parameters and the obtained response in each simulation (colurim 8). The obtained results are shown in Pareto chart (Fig. 7). 

Doehlert designs of type D-2, in coded units. To obtain the full designs, the matrices must be augmented with the origin and the negatives of all runs. The integers at the bottom of each design indicate the number of factor levels... 

If all variables are quantitative it is advisable to add a centre point into the design, i.e. an experiment where all variables are set to their mean values. Consequently, in coded units, all variables have value 0. The centre point experiment can be used to detect nonlinearities within the design area. If the mean experimental error is not known, usually the most effective way to find it out is to repeat the centre point experiment. AU experiments, including the possible centre point replicates, should be carried out in random order. The importance of randomization is well explained in e.g. (Box, Hxmter Hxmter). 

The design was chosen to be a fractional resolution V design (25-i) with the generator I = 12345. The design table in coded units, including the yields and the run order of the experiments is given in Table 10 (y stands for the yield). 

Next, the variables are coded so that the maximum values are set to +1 and the minimum values are set to -1. Thus the coding for design in coded units is given in Table 21. 

Table 21. A Doehlert design with 2 variables in coded units.

The designs as given in this section are analyzed in terms of model equations that simulate the. system under study. The designs and the model equations are set up using special coded units for the independent variables (factors) of the design. Thus for the response variable i and two independent variables Y and. v.->. the model equation that allows for the evaluation of any interaction between. V and. xs is... 

The selection of the physical units that represent the coded units of both screening and exploratory designs should be carefully thought out. In a screening design, the lower and upper physical unit levels should be as wide as possible to increase the sensitivity of the evaluation. The values should also be in the range of direct interest to the technical... 

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