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Low Distillation Stagecount Design for Shipboard ASUs

IP.com Disclosure Number: IPCOM000019413D
Publication Date: 2003-Sep-12
Document File: 1 page(s) / 83K

Publishing Venue

The IP.com Prior Art Database

Abstract

In Shipboard applications the height of a distillation column is particularly important, as shorter columns should be less susceptible to ship motions; forces other than gravity, due to column motion, can cause liquid maldistribution leading to reduced column stage efficiency. Therefore, when considering the design of a shipboard ASU, factors other than power and capital cost come into play, which may affect optimisation of the plant design.

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Low Distillation Stagecount Design for Shipboard ASUs

In Shipboard applications the height of a distillation column is particularly important, as shorter columns should be less susceptible to ship motions; forces other than gravity, due to column motion, can cause liquid maldistribution leading to reduced column stage efficiency. Therefore, when considering the design of a shipboard ASU, factors other than power and capital cost come into play, which may affect optimisation of the plant design.

Most shipboard applications are endowed with a low power cost, due to the abundance of natural gas and therefore the design of an operable column becomes less tied to the cost of power.

It has been discovered that the power penalty for using extremely low column stage counts for conventional double column shipboard ASUs, may be acceptable for shipboard ASUs.

For example, take a conventional double column pumped LOX cycle for the production of low (95% O2) purity GOX, which produces refrigeration by expanding feedair to the LP column. The power penalty for using a total stagecount of only 16 (9 LP and 7 HP) is less than 10% when compared to a design using a more ‘normal’ stagecount of say 55. If refrigeration is generated by expansion of boosted air to the HP column then low stage counts are even easier to justify. Of course, if high purity oxygen were required, then the optimum stagecount would be higher than for low purity oxygen. Nevertheless the power penalty for using much low...