Cold Selective Catalytic Reduction - CSCR
OnQuest is pioneering the development of a new, lower-temperature selective catalytic reduction unit that uses regenerative heat exchange to minimize the amount of additional heat required during the oxidization process.
Known as cold SCR (or simply, CSCR), this new technology can have significant benefits for thermal efficiency, as flue gases can be treated with low exhaust gas temperatures of about 200 - 300 °F (95 - 150 °C), therefore allowing the thermal oxidization to take place after economizer or waste-heat recovery units.
Not every situation is well suited for a traditional SCR unit. For example, it is typically not convenient to divert the flue-gas stream into an SCR unit from a point in the process where the temperature of that stream is above 600°F (315°C), especially for a retrofit application. Frequently, the gas stream needs to be heated to about 700°F (370 °C), then cooled again after the SCR such that the draft fan does not need to be of special construction to survive.
As a result, various conditions should be considered before adopting cold SCR:
- The extra heat-exchange equipment needed to retrofit a conventional SCR system can be costly,
both in terms of the initial equipment purchase and installation, and the operation and maintenance expenses.
- Location can present challenges, since in many cases there is no room for additional equipment.
Cold SCR also presents some benefits:
- Using regenerative heat recovery is a practical method for combining multiple effluent gas streams into a single
feed stream, allowing one unit to treat a facility or process unit.
- The heat transfer media can also serve as the guard-bed, protecting the catalyst.
- The cold SCR unit can save as much as 95% in fuel consumption, for only a 6% increase in power use,
when compared to a conventional SCR unit.
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