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Heuristics

12 Oct 12

Homework: Problem 11.1 Turton

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Example

Estimate size of heat exchanger E-

105

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In Class Exercise

Estimate size of reboiler E-106

Given:• mps (medium pressure steam) = 10 barg• T-101 operates at 3 bar• From simulation, reboiler duty =

2,512,500 W

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Heat ExchangersAdditional Experience-Based Principles:

Gael D. Ulrich and Palligarnai T. Vasudevan, Chemical Engineering Process Design and Economics, a Practical Guide, 2nd ed., Process Publishing, Durham, NH, 2004

Posted on the website will be Ulrich’s guide/shortcut/rules of thumb for heat exchanger design and flowsheet preparation.

9Ulrich, 2004

10Ulrich, 2004

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www.pfaudler.com

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www.pfaudler.com

13ACHEMA, Frankfurt, June 2012

Spiral-like HE

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ACHEMA, Frankfurt, June 2012

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Air Cooled Heat Exchangers

Ulrich, 2004

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Air Cooled Heat Exchangers

Ulrich, 2004

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Air Cooled Heat Exchangers

www.gearainey.com

Applications.. air coolers are installed throughout the world in the following applications:• Forced and induced draft air cooled heat exchangers• Recirculation and shoe-box air cooled heat exchangers• Hydrocarbon process and steam condensers• Large engine radiators• Turbine lube oil coolers• Turbine intercoolers• Natural gas and vapor coolers• Combustion pre-heaters• Flue gas re-heaters• Lethal service• Unique customizations

Air cooled heat exchangers can be used when:• Cooling water source not readily available• Cooling water systems adds complexity or cost to facility• Lower operating / maintenance cost could be achieved

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Air Cooled Heat Exchangers

www.gearainey.com

Minimizing Air Cooler CostsGEA Rainey Corporation has developed a short list of points to help you create the most economical design and assist with an initial design; most of the time GEA can provide more economical designs.

• Maximize tube length while maintaining >=40% fan coverage

• Design aircooler with a 1 to 3 ratio. For example, if your cooler is 30’ long it should typically be around 10’ wide. This helps reduce the header size, the most expensive portion of an aircooler, while still maintaining proper fan coverage.

• Minimize tube rows to increase heat transfer effectiveness of area, minimize header thickness. Typically between four to six tube rows

• Try and maintain 1” tube diameters, depending on service. Even high viscosity services that appear to benefit from larger diameter tubes can typically be designed cheaper with more 1” diameter tubes.

• Use a counter-current flow where possible as it reduces surface and potentially minimize header plate thickness.

• Increase your allowable pressure drop. This allows more passes in the bundle reducing the cooler size.

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Air Cooled Heat Exchangers

Ulrich, 2004

20Ulrich, 2004

21Ulrich, 2004

22Ulrich, 2004

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Guidelines for Equipment Design

Ulrich, 2004

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Ulrich, 2004

25Ulrich, 2004