Experimental program 6.1 Basis
6.5 Reporting results from the experimental program
6.5.1 Frequent partial reports
It has been noted (in Section 6.1.4) that one of the main bottlenecks of any development project is always the calculation of the practical impli- cations of the results obtained from the experimental work and their presentation by the process engineering group. (The professional joke refers
to the period in which a process engineer is requested to work 24 hours a day and then continue the work through the night.) If these results can be made
available in a series of successive self-contained reports, each dealing with one section of the process block diagram, the process engineering group can start to correlate and work out these results as they come, making better use of their limited resources.
It is, therefore, important to agree on a transmittal procedure, which can include eventually the transmittal of draft reports (with due reserva- tions) if certain details are still not available. It is also important to identify clearly these reports as any other project documents with the code number, revision number, date of issue, and name of the responsible person for further contacts.
6.5.2 Complete reports on the experiment part
In many projects, it has been seen that such experimental reports were handled and written as internal memos of current value only. The authors of these documents seemed to assume that the limited number of readers
should remember all the details of “last week’s discussions” and, thus, there was no need for further detailing. Such practice often caused serious misinterpretations.
But more importantly, these experimental results have been often retrieved a few years later for further studies in order to improve or expand the plant’s operation. In many cases, unfortunately, they could not be used for lack of critical factual information. It is therefore very important that all these exper- imental reports are written as self-contained complete scientific reports, which can be used also by a “new guy” who has just arrived on the project.
They should include full details on the purposes, the procedure, the materials, the sampling and analytical methods, the numerical results, the calculations procedure, any reference documents, the names of the respon- sible personnel and all the participants, and any observation or reservation or recommendations as regards the value of the results.
The few extra hours required for a complete report would be well invested and would be recovered, in any case, when the “process package” is prepared (see Chapter 7), although possibly by a different team.
6.5.3 Implications of the results
Finally, it is important as well to prepare and present a comparison of the numerical values from the experimental results actually obtained in the tests with the assumptions or extrapolations used by the process engineering group in the preliminary process working definition (see Chapter 5, Section 5.1). Reasonable differences can be expected and the overall effect can be evaluated readily in a recalculation of the balances with the already available spreadsheets. But if these differences or their implications are larger and more significant, a review meeting should be called to decide on any change in the program.
6.6 Worth another thought
• There is not much point in designing and starting any significant experimental program without performing first the process engineer- ing analysis and being reasonably sure that the results would remain in the range of interest for the further application considered. • The main purpose of the experimental program is the collection,
correlation, and presentation of the design data that is specifically needed for the new process design and optimization in the limited range of variables of practical interest. Another important purpose is to observe possible, but unexpected, problems that can occur and that should be dealt with.
• If representative samples of the actual raw materials cannot be readily procured, an experimental program on “synthetic” mixtures can only be done as an exploratory work for the preliminary process design.
• Since, in most cases, there are more than two components present in each phase, one has to decide from the start which two compo- nents are the variables under study while the other components are to be considered as parameters for the purpose of the present pro- cess design.
• Very hot organic liquid or vapor “heat carrier” can be introduced in direct contact with the corrosive process stream. After heat transfer and equilibration, the organic liquid is separated, removed, washed, and reheated in a separate boiler made of cheaper materials. • The experimental technique called “limiting conditions” make it eas-
ier to study, specifically, the effect of one variable at a time.
• Many of the solid precipitates can be clearly identified and quantified by established mineralogical techniques in addition to the usual chemical analysis methods. The collaboration of a mineralogical lab- oratory can be a great help in a R&D program.
• With “real systems” testing, the total numerical data collected repre- senting one “equilibrium point” amounts to possibly 10 to 20 num- bers, and its recording and presentation can be only in the form of systematic tables.
• A 50,000 MTY fermentation plant with a batch turnover of 4 days and a product concentration of the order of 10% in the fermentation broth, needs 34 fermentors of 200 m3 each (5 m diameter and up to 10 m high). The hydrostatic pressure at the bottom is an important operating parameter.
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