Troubleshooting a process

Several tools are very important for troubleshooting a process. These tools include measuring devices for determining the geometry of the screw, measuring temperature, and collecting process data. Troubleshooting a process without these tools... 

TIP To troubleshoot a process efficiently, try to view the operations firsthand. 

To do competent troubleshooting, a process technician should have ... 

Some of the instruments only indicate or record the process variable and have no control function whatsoever. Other instruments, called controllers, are the nerve center of the process unit. The operating engineer troubleshooting a process problem should locate all of the controllers on the panel board. Those controllers will have the following features. 

Data Acquisition As part or the understanding, the measurements that can be taken must be understood. A useful procedure to prepare for this is to develop a tag sheet for the process (Lieberman, N.P., Troubleshooting Refinery Processes, PennWell Books, Tulsa, 1981, 360 pp). An example of a simplified sheet is given in Fig. 30-5. 

The specific energy from Eq. 10.13 is reported in J/g for convenience in analyzing the process. If a change in a process causes the specific energy to increase by 50 J/g, the troubleshooter can translate this to an adiabatic temperature increase of 20 °C because many unfilled resins have heat capacities near 2.5 J/(g °C). This temperature change calculation, however, is an approximation because extruders typically do not operate adiabatically. 

For existing lines, the processor must understand the rate-limiting step for the process, if a rate increase is desired and the troubleshooter improves a section of a line that is not the rate-limiting step, then a rate gain will not occur. Sometimes the rate-limiting step for a process is not obvious and can be difficult to determine. 

The standard array of diagnostic equipment is required for the troubleshooting of a process that is flow surging. These tools include screw measuring devices, pyrometers, and devices to calibrate sensors in the process. These devices are discussed in Chapter 10. Often it is very difficult to Impossible to determine a cause and effect relationship from process displays that are attached to typical extrusion... 

Norman P. Lieberman is a chemical engineer with more than three decades of experience in process design and plant operations supervision. Currently an independent consultant, he troubleshoots refinery process problems for such companies as Chevron, Olin, and Texaco. 

Elizabeth T. Lieberman is a chemical engineer holding a B.Sc. in Chemical Engineering from the University of Wales, and an LIRC. in Chemistry. Elizabeth has two decades of experience in the process industries, and is currently working as a consultant troubleshooting refinery process problems and assisting Mr. Lieberman with the presentation of his seminars. 

In 1983, I started teaching a three day process equipment troubleshooting seminar, to chemical engineers and experienced plant operators in the petroleum refining and chemical process industry. Since the inception of the seminar, in excess of 5000 men and women have attended the classes. The seminar is largely based on my 30 years experience in field troubleshooting, and process unit revamp design. 

New ideas for a process — Determining process chemistry —> Pilot plants studies — Plant design — Plant startup —> Debottlenecking or troubleshooting. 

Process diagrams are a necessary part of a plant. Flow and P I diagrams aid the process engineer in understanding, controlling, and troubleshooting the process. They also provide valuable information about the process in the event of an emergency. 

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