Revamping a nitric acid plant with a high pressure bleacher to increase capacity

The Casale HP bleacher revamping scheme ensures a substantial capacity increase of dual pressure nitric acid plants. The underlying strategy is to install a new air compressor that supplies the additional feedstock air at the same pressure level of the absorption section. This additional air is used to bleach the nitric acid through a new dedicated equipment: the HP bleacher.

The main air compressor is then emptied of the secondary air, and this extra air can be used to proportionally increase the nitric acid capacity.

The revamping target is then achieved with little or no impact on the major key equipment: the turbo compressor set. Considering that the dual pressure plant turbotrain is a 4 in 1 machine, any overhaul is highly demanding and by minimising the interventions the following distinctive advantages can be achieved:

• Minimising the shutdown period, shortening the revamping intervention schedule.
• Limiting the expensive and critical activities on the Turboset.
• No need to compromise the operation of the plant at the original capacity turndown.
• Low CAPEX.

The presentation covers the major features of this revamping approach.