CASE STUDY: Desuperheater in Combined Heat & Power Plant (CHP)

savings and environmental benefits

Challenge:

A CHP plant located in the UK generates superheated steam as a by-product of its electrical energy production. The superheated steam exiting the turbine needs to be desuperheated prior to being sent onto secondary users.

The exit steam was passed through an existing desuperheater which was not able to provide a consistent steam temperature. Due to this controllability issue, the plant was forced to utilize a back-up boiler to feed secondary processes.

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Solution:

Kadant Johnson Systems identified the type of desuperheater installed by the original system supplier was not the proper design for the application. It was recommended the existing unit be replaced with an atomizing ejector type desuperheater to improve controllability and overall performance.

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Results The desuperheater is now allowing for turbine exhaust steam (i.e waste steam) to be used in secondary plant processes. The back-up boiler is now redundant and used as a stand-by unit. Assuming the back-up boiler was generating a ton of steam for £20/ton, at an hourly production rate of 25tn/hr for 8,000 hours production per year, energy savings added up to £4 million pounds (US $5.2 millions) per year. In addition, the CHP plant realized environmental benefits (e.g CO2 reduction and reduced water consumption) of not having to burn gas in the backup boiler to generate steam for this secondary requirement.