Gantt

Figure 4.11 A Gantt or time-event chart of the batch process.

Batch processes can be synthesized by first synthesizing a continuous process and then converting it to batch operation. A Gantt (time-event) diagram can be used to identify the scope for improved equipment utilization and the need for intermediate storage. 

Simple production of bar charts or Gantt charts detailing the task time scales ... 

With time duration determined for each task of the project, the next step is to determine the earliest and latest starting times for each task. There are two commonly used methods for charting the project Gantt charts and PERT diagrams. The details of these two methods are discussed on the following pages. 

A Gantt chart is a horizontal bar chart that graphically displays the time relationship of the steps in a project. It is named after Henry Gantt, the industrial engineer who introduced the procedure in the early 1900s. A line placed on the chart in the time period when it is to be undertaken represents each step of a project. When completed, the Gantt chart shows the flow of activities in sequence as well as those that can be under way at the same time. 

To create a Gantt chart, list the steps required completing a project and estimating the time required for each step. Then list the steps down the left side of the chart and time intervals along the bottom. Draw a line across the chart for each step, starting at the planned beginning date and ending on the completion date of that step. 

When your Gantt chart is finished, you will be able to see the minimum total time for the project, the proper sequence of steps, and which steps can be under way at the same time. 

You can add to the usefulness of a Gantt chart by also charting actual progress. This is usually done by drawing a line in a different color below the original line to show... 

Gantt charts are limited in their ability to show the interdependencies of activities. In projects where the steps flow in a simple sequence of events, they can portray adequate information for project management. However, when several steps are under way at the same time and a high level of interdependency exists among the various steps, PERT diagrams are a better choice. 

PERT is an acronym for Program Evaluation and Review Technique. It is a more sophisticated form of planning than Gantt charts, and is appropriate for projects with many interactive steps. There are three components of a PERT diagram circles or other convenient, closed figures represent events arrows connecting the circles represent activities and non-activities connecting two events are shown as dotted-line arrows. (A non-activity represents a dependency between two events for which no work is required.)... 

Figure 9.12 Gantt chart for the tasks outlined in Figure9.11.

CUNNINGHAM F X Jr and GANTT E (1998) Genes and enzymes of carotenoid biosynthesis in plants , Ann Rev Plant Physiol Plant Mol Biol, 49, 557-83. 

CUNNINGHAM F X Jr, POGSON B, SUN Z, MCDONALD K A, DELLAPENNA D and GANTT E (1996) Functional analysis of the (3 and e lycopene cyclase enzymes of Arabidopsis reveals a mechanism for control of cyclic carotenoid formation . Plant Cell, 8, 1613-26. 

SUN z R, GANTT E and CUNNINGHAM F X Jr (1996) Cloning and functional analysis of the (3-carotene hydroxylase of Arabidopsis thaliana , J Biol Chem, 271, 24349-52. 

Kato, M. et al.. Accumulation of carotenoids and expression of carotenoid biosynthetic genes during maturation in citrus fruit. Plant Physiol. 134, 82, 2004. Cunningham, F.X. Jr. and Gantt, E., One ring or two Determination of ring number in carotenoids by lycopene epsilon-cyclases, Ptvc. Natl. Acad. Sci. USA 98, 2905, 2001. 

Cunningham, EX. Jr. and Gantt, E., Identification of multi-gene families encoding isopentenyl diphosphate isomerase in plants by heterologous complementation in Escherichia coli. Plant Cell Physiol. 41, 119, 2000. 

Figure 7.4-1. Gantt charts (a) non-overlapping mode, (b) overlapping mode, (c) overlapping, parallel units out-of-phase. 

Fig. 7.4-4 shows Gantt charts for a four-product, three-stage plant for which processing times are given in Table 7.4-6. At each stage (unit) the processes are arranged in the following order P1-P2-P3-P4. 

For a single-product plant the calculation of equipment sizes is straightforward. First the limiting cycle time ti is determined using Eqn. (7.4-14) or Gantt charts. The batch size is then evaluated for an assumed production capacity Q and available production time H ... 

Without making Gantts charts, it is obvious from these data that the limiting times are tz,i = 8 h and tL2= 12 h. Now, capacities of both vessels can be calculated using expression (7.4-52). For vessel 1 ... 

The. sequencing is not known a priori. The Gantt charts in Fig. 7.4-13 illustrate the essence of sequencing. 

Cross JB, Jalaie M, Gantt SL, Joshi NA, Wild DJ, Snow ME, Narasimhan LS (2004) Abstracts of Papers, 227th ACS National Meeting, Anaheim, CA, United States, March 28-April 1, 2004 COMP... 

Figure 14.14 Gantt chart for a simple batch process.

Figure 14.23 Gantt chart for a repeated batch cycle for Example 14.2.

The Gantt chart shown in Figure 14.23 indicates that individual items of equipment have a poor utilization. To improve the equipment utilization, overlapping batches are shown in Figure 14.24. 

Figure 14.27 Gantt chart for Example 14.2 with intermediate storage.

Production schedules for batch processes can be sequential, overlapping, parallel, use intermediate storage, or use a combination of these. Such schedules can be analyzed using Gantt charts. Batch processes often produce multiple products in the same equipment and can be distinguished as flowshop or multiproduct plants. Equipment cleaning and material transfer policy have a significant effect on the production schedule. 

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