Pulling a production boost out of thin air

The steady growth of global demand for cement and the hefty rise in energy prices pose two important questions for owners and operators of cement plants: ‘How can we increase production capacity?’, and ‘how can we reduce energy consumption?’.

An even trickier question is: ‘How can we achieve both at the same time?’ Thankfully, the answer may be simply found in the air – through oxygen enrichment.

How can oxygen enrichment help in cement production?

Oxygen enrichment describes the process of introducing an oxygen-enriched air stream into the combustion processes of a cement plant.

By increasing the oxygen content in an air stream to about 25 – 40% at the kiln and precalciner, several benefits can be observed:

• Improved combustion efficiency and production capacity.
• Achievement of a stable thermal field, which accelerates the generation of calcium silicate and results in increased clinker quality.
• Reduced energy consumption and coal usage.

The conventional method for introducing oxygen into an air stream is through an air separation unit, which liquefies atmospheric air at very low temperatures (-300°F) and then separates the oxygen through continuous cryogenic distillation. The oxygen is then stored as a liquid in cryogenic storage tanks at very low temperatures. Due to the strong oxidising properties and highly reactive nature of oxygen, temperature increases need to be avoided to prevent unwanted vaporisation and reduce the safety risks. In addition to being an energy-intensive process (with energy requirements of 200 kWh/t of oxygen), liquid oxygen poses an unwanted and unnecessary safety risk to the site.1 So, it is easy to understand why this technology has not often been used.

A much safer and more economical solution for oxygen-enrichment is a gas separation membrane. Gas separation membranes are a proven technology for the generation of nitrogen-rich air streams. The ‘offgas’ can be used in oxygen-enrichment applications since it contains 30 – 40% oxygen, and is therefore ideal for enhancing the cement production process.

Enjoyed what you've read so far? Finish the article and access the entire December issue of World Cement by registering, free of charge, here.

Read the article online at: https://www.worldcement.com/special-reports/23122022/pulling-a-production-boost-out-of-thin-air/