Methanol purification

Technology from Valmet can help mills become fossil free

New Valmet technology purifies methanol in Kraft pulp mills

Fossil-free mills with lower NOx emissions

Purified methanol is a renewable, high-quality fuel. Since most of the nitrogen in the methanol is removed, fuel NOx is practically eliminated and NOx emissions are lower. The even quality enables better control of the lime kiln flame. The purified methanol also works well as a start-up and support fuel. Purified methanol can help reduce the need for fossil fuels.

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Upgrade of the methanol plant for production of low-NOx methanol

Methanol for chlorine dioxide production

Some of the most important technologies for producing chlorine dioxide, a common bleaching chemical, use methanol as a reducing agent. If locally produced methanol is used, the mill’s costs for imported methanol can be lowered considerably.

Existing methanol plants can be upgraded

The Valmet methanol purification technology is designed as an upgrade to existing methanol plants. A low-NOx module is installed upstream from the methanol plant. This mainly removes nitrogen and water from the stripper off gas. The output from the methanol plant is low-NOx methanol, a good support fuel for the mill. If further purification is needed, two distillation columns are installed after the methanol plant. Distillation of low-NOx methanol results in one stream of very pure methanol and one stream of low-NOx methanol.

 

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Overview of the Valmet methanol purification technology. The low-NOx purification is located upstream from the existing methanol plant and the two distillation columns downstream from it. Distillation of low-NOx methanol results in one stream of low-NOx methanol and one stream of purified methanol.

Chemical consumption and sulfur recovery

The Valmet methanol purification process uses sulfuric acid to convert ammonium into ammonium salts and promote separation of TRS components. The extracted oil (red oil) contains sulfur and can be incinerated in the recovery boiler.

Distillation

Distillation of low-NOx methanol removes carbon compounds like ethanol and acetone. Distillation is needed if the target is to use the purified methanol in the mill’s chlorine dioxide plant. The distillation technology is similar to the one in traditional methanol plants.

Small footprint, attractive investment level

The Valmet methanol purification technology has a small footprint and can be installed in a relatively limited space. Valmet methanol purification makes it possible to upgrade existing methanol plants at very attractive levels of investment.