Material balance preparation

The over-all material balance, prepared for the test period on the combined operation of the thermal reformer and the polymerization unit, appears in Table II. It is based on the streams actually fed and produced. Table III shows the debutanized reformate and debutanized polymer streams separately and as a combined stream. Laboratory inspections of the debutanized reformate and of the debutanized reformate plus polymer blend are presented in Table I. 

Material balance Prepare sample points Unplug pressure taps Optimize unit operation Issue written instructions... 

Material Balance Constraint There are two types of constraints for the unit. These are the process constraints and the equipment constraints. In each of these, there are equahty constraints such as material balances and inequality constraints sucti as temperature limits. Analysts must understand the process and equipment constraints as part of the preparation for the unit analysis. 

During this preparation stage, analysts will frequently find that there is insufficient quantity or quality of measurements to close the material balance. Analysts should make eveiy effort to measure aU stream flows and compositions for the actual test. They should not rely upon closing material balances by back-calculating missing streams. Tne material balance closure will provide a check on the vahdity of the measurements. This preparatoiy material balance will help to identify additional measurements and schedule the installation of the additional instruments. 

Step 12 Final Preparation for the Material-Balance System... 

The team is now at the point where it can prepare a material balance at a scale appropriate to the level of detail required in the assessment. For example, you may require a material balance for each unit operation, or one for a whole process may be sufficient. Decide on various levels of detail that may be needed. 

Now you can reconsider the material balance equations by adding those additional factors identified in the previous step. If necessary, estimates of unaccountable losses will have to be calculated. Note that, in the case of a relatively simple manufacturing plant, preparation of a preliminary material-balance system and its refinement (Steps 14 and 15) can usefully be combined. For more-complex P2 assessments, however, two separate steps are likely to be more appropriate. An important rule to remember is that the inputs should ideally equal the outputs - but in practice this will rarely be the case. Some judgment will be required to determine what level of accuracy is acceptable, and we should have an idea as to what the unlikely sources of errors are (e.g., evaporative losses from outside holding ponds may be a materials loss we cannot accurately account for). In the case of high concentrations of hazardous wastes, accurate measurements are needed to develop cost-effective waste-reduction options. It is possible that the material balance for a number of unit operations will need to be repeated. Again, continue to review, refine, and, where necessary, expand your database. The compilation of accurate and comprehensive data is essential for a successful P2 audit and subsequent waste-reduction action plan. Remember - you can t reduce what you don t know is therel... 

Phases I and II have eovered planning and undertaking a P2 audit, resulting in the preparation of a material balance for each unit operation. Phase III represents the interpretation of the material balance, to identify process areas or components of concern. 

As indicated previously, Eq. (4.5.1) may be applied to die total mass of each stream (referred to as an overall or total material balance) or to die individual eomponents of the streams (referred to as a componential or component material balance). Often the primary task in preparing [Pg.120]

Prepare heat and material balance studies for a proposed process, both by hand and by use of computer programs. 

Prepare final detailed heat and material balances. 

Other preparations and isolations. If damp methylenedi(nitroformamide) is allowed to stand for several days, the odor of formic acid is noticed, and MEDINA can be isolated from the residue (Ref 11, p 14). The details of scale-up to 150 lb batches, including exp details and flow sheets, and further scale-up with the aim of prodn of 1000 lbs are given. The report describes a fume-off and fire which occurred during the S3rd run. The cause was attributed to a stuck valve which allowed nitric acid to build up in the reactor (Ref 13, p 57). In Ref 16, p 73 there are cost analysis data for pilot plant and large scale prodn, flow sheet for a proposed coml plant, and material balances. The action of acet anhydr on N,Nf-bis(hydroxy-methyl)MEDlNA regenerates MEDINA (Ref 6) the diNa salt of N. N trinitrotrimethylene-diamine, on warming with me ale, ppts the Na salt of MEDINA... 

This section is a general discussion of the techniques used for the preparation of flowsheets from manual calculations. The stream flows and compositions are calculated from material balances combined with the design equations that arise from the process and equipment design constraints. 

Prepare a material balance on an hourly basis for the complete process in weight units. 

The material balance equations for the FCC unit are easily expressed in terms of the yield equations presented earlier. If F represents the total inlet feed (barrels per day, BPD) to the FCC unit and Y, is the yield of product i as read from Tables 2.3 and 2.4, then the production of product i can be simply obtained by multiplying the feed to the unit by the yield of product i (i.e., FY ). Such material balance equations must be written for all units of a refinery in order to prepare a mathematical... 

Figures 1 through 4 are plots of certain data given in Table I, prepared to facilitate interpolation required in working up material balances.

The data herein presented were gathered with that purpose in mind, and answer the objective, at least in part. The influent and effluent stream volumes, specific gravities, and concentrations enable the preparation of materials balances around the ion exchange units. However, such material balances are no better than the data on which they are based. Therefore, it is advisable to consider the assets and liabilities of the data. 

This result means that one is free to specify four phase-rule variables, for example, T, P, and two mole fractions, in an equilibrium mixture of these five chemical species, provided that nothing else is arbitrarily set. In other words, there can be no special constraints, such as the specification that the system be prepared from given amounts of CH4 and H20. This imposes special constraints through material balances that... 

Gather all the available information on one of the ethylene processes for which a flow sheet was prepared in the preceding problem and make a preliminary material balance for the production of 50 million lb/yr of ethylene. Assume an operating factor of 90 percent. 

Prepare a material balance and a qualitative flow sheet for the production of 7800 kg/h of acetaldehyde using the process described in the previous problem. Assume an operating factor of 90 percent and a 95 percent yield on the ethylene feed. Both ethylene and oxygen enter the process at 930 kPa. 

An alternative method of preparation of the cyclohexyl radical which has been used is by the reaction of the phenyl radical (prepared from phenyl iodide and sodium) with a matrix of cyclohexane. Clearly the amount of cyclohexane formed by the disproportionation reaction cannot be measured. However, the amount of benzene, formed in the initial abstraction reaction, is equal to that of the cyclohexyl radicals and thus also to the total amount of products formed by the cyclohexyl termination reactions. Thus a mass balance can be made and values of k jkc (Table 9) calculated on the same basis as before (Fig. 20). An upper limit of the value of k jk can be obtained from these experiments on the assumption that no side reactions occur. The material balance gives... 

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