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Technical & Practical

Tank Vapors: Optimize Ejector Sizing for Better Control

Properly sized ejector stations can save capital costs and reduce downtime Steam-assisted, gravity-drainage (SAGD) operations employ large tanks that vent flammable and sometimes toxic gases. Safety and environmental concerns often require engineers to design vapor-recovery units (VRUs) to collect these…

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Calculate Liquid Volumes in Tanks with Dished Heads

This article presents equations that allow the user to calculate liquid volume as a function of liquid depth, in both vertically and horizontally oriented tanks with dished heads. The equations accommodate all tank heads that can be described by two…

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Sterilization Approaches

Maintaining high-purity conditions in the chemical process industries (CPI) depends in large part on the techniques used for sterilization. As a method to inactivate or eliminate potentially harmful microbes, sterilization can be achieved through a number of different approaches, such…

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Todays Process Automation Worlds

Modern industrial-automation systems rely entirely on digital technology, that is, computers. And as is typical of digital products, suppliers love to add features — data collection, alarm management, and so on — that are very useful for process operations but…

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Evaluating Capital Cost Estimation Programs

Capital cost assessment is an integral part of process design when building or expanding a chemical process plant. It is required to provide project analysis and evaluation, to select among alternative designs, to plan the appropriation of funds and to…

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Heat transfer system cleaning

A well designed and operated heat-transfer-fluid system is a key feature of a safe, reliable and cost-effective heating design. However, problems can arise if the heat-transfer fluid becomes heavily degraded or the system is allowed to accumulate solids and other…

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How long does it take to reach steady state?

How long does it take a six-tray, 4-ft dia. deisobutanizer to achieve steady state? That depends on your definition of “steady state”. Some control experts regard 95% of “ultimate value” as a good definition, but how useful is that definition?…

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Preventing Self-Heating and Ignition in Drying Operations

Many solid materials can exhibit self-heating, which — if unchecked — can progress to a fire or even explosion. And even if the situation does not get that far, it is likely to affect the output of the process, in…

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When troubleshooting the extractor

I have an ongoing dispute with a longtime colleague, Bob Miller. I said he ruined my new safety boots. He said he didn’t. Bob was a young, fearless distillation engineer at a time when our extraction engineer refused to take…

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Gas-Liquid Mixing: Physical Considerations

Gas-liquid reactors in the chemical process industries (CPI) have increasingly been designed to handle larger manufacturing scales. Since gas-liquid reactors can represent substantial capital and operating costs for the user, optimizing mixing and maximizing productivity are critical. The need for…