Startup step

Gans, M., Kiorpes, S. A., and Fitzgerald, F. A., Plant Startup—Step By Step By Step, Chemical Engineering, October 3, 1983, p. 99 (Inset Some afterthoughts on startups). 

The above sequence of steps is typical of shutdown operations. Other comments made above regarding the sequence of startup steps extend also to the sequence of shutdown steps. 

In the multistep production of IPDI, isophorone is first converted to 3-cyano-3,5,5-trknethylcyclohexanone (231—235), then hydrogenated and ammoniated to 3-aminomethyl-3,5,5-trknethyl-l-aminocyclohexane (1) (236,237), also known as isophorone diamine (IPDA). In the final step IPDA is phosgenated to yield IPDI (2) (238). Commercial production of IPDI began in the United States in 1992 with the startup of Olin s 7000 t/yr plant at Lake Charles, Louisiana (239), and the startup of Hbls integrated isophorone derivatives plant in Theodore, Alabama (240). Hbls has a worldwide capacity for IPDA of 40,000 t/yr. 

The flowchart on the next page shows an overview of steps for the pre-startup and startup phases of a typical tolling process. 

The question to answer for this pre-startup task is Who needs training for this process and to what level of detail One method to analyze training needs is offered by the Instructional Systems Design (ISD) technical training model. It points to the job task analysis method mentioned previously (Appendix D, ISD Model and Job Task Analysis Techniques) to identify procedure titles as a first step for determining which job positions require specific knowledge and skills. 

Test run steps can frequently be incorporated into process startup procedures. Two examples would be pulling a vacuum on vessels and verifying it holds, or distilling a solvent and checking for the presence of water to verify the mechanical integrity of the heating and cooling equipment. 

When a test run is performed using the actual materials for the toll, it is a prime opportunity for the toller and the client to document the capability of the equipment, instrumentation, and process steps. During such a test, frequency of sampling may be increased, additional analyses performed and yield capabilities checked to find the optimum setpoints and timing for the toll process. Health, safety and environmental staff may choose to provide close coverage of the test run to evaluate areas for improvement during the actual startup and long term operation. 

Step 4. A study of starting characteristics of the train is necessary to select the correct startup driver rating (motor and/or steam turbine). 

The next step is to address the startup drivers in the power reeovery eases and determine the general equipment aiTangements. Some general eriteria used to begin determining the equipment arrangement inelude ... 

Preliminary steps for the initial startup and startup after the overhaul are similar, except for the reservoir and oil requirements on the machine after an overhaul. For an overhauled machine, the oil is drained and tested for condition. If there is no water or metal changes, the oil may be used again. 

Starting preparations. The steps neeessary to prepare the serviees and apparatus for a typieal startup are as follows ... 

An additional capacity control method is the unloader. This method can be used in conjunction with clearance pockets to extend the range of control to zero capacity. On double-acting cylinders, unloading the individual sides one at a time will provide a two-step unloading of the cylinder. On multicylinder arrangements, the cylinders can be unloaded one at a time providing as many steps as cylinders operating in parallel. The unloaders can also be used to totally unload the compressor, as is necessary for electric motor driver startup. 

Ideally the compressor can be placed on the foundation, aligned, grouted, and piping connected. Shortly thereafter, the unit can be started. Most of the time there are lags between the various steps. User careles.s-ness here can delay ultimate startup and may mar what otherwise might have been a very successful installation. 

The next two steps after the development of a mathematical process model and before its implementation to "real life" applications, are to handle the numerical solution of the model s ode s and to estimate some unknown parameters. The computer program which handles the numerical solution of the present model has been written in a very general way. After inputing concentrations, flowrate data and reaction operating conditions, the user has the options to select from a variety of different modes of reactor operation (batch, semi-batch, single continuous, continuous train, CSTR-tube) or reactor startup conditions (seeded, unseeded, full or half-full of water or emulsion recipe and empty). Then, IMSL subroutine DCEAR handles the numerical integration of the ode s. Parameter estimation of the only two unknown parameters e and Dw has been described and is further discussed in (32). 

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