CapWa, a new source of water

Water and energy recovery from flue gases

Pressure on the world’s water resources is increasing, yet there are always large quantities of water vapor present in the atmosphere. Many industrial processes result in the production and/or liberation of water, which escapes into the atmosphere in the form of vast quantities of wastewater. This waste water usually leaves the plant from a single point, namely the stack. It is ironic that, although a great deal of emphasis is placed on capturing or reducing CO2 emissions from plants that burn fossil fuels, little attention has been given to capturing the water vapor, which is also formed during combustion.

Using membranes to capture water vapor has several technological and economic advantages over using heat exchangers. The water produced was found to be close to demineralized water in terms of quality. Furthermore, the fouling that occurred was easily tackled with in-situ cleaning systems, which returned the water flux to normal levels.

Project
The objective of this project is to transfer the technology from lab scale to industrial scale. The starting point will be the composite membranes developed in the proof-of-principle project, which can selectively catch water vapor. The membrane concept is based on a gasseparating composite membrane capable of recovering evaporated “waste” water. As well as refinement of the proven membrane, the project will involve fundamental research on other water-selective membranes. To prove the viability of the technology, practical field tests and efficient production processes that are friendly both to users and to the environment will be developed and researched. To help support and speed up development of the end-user system, different modeling tools will be used. Thereafter, technical and economic studies will be undertaken. In addition, average water- and energy-saving performance values will be determined for the industries involved.

Objectives
This project aims to provide an innovative and potentially rich solution to the shortage of water. The goal is to have membrane modules that are suitable for industrial applications and competitive with existing technologies available within 3 to 4 years. Membrane modules will be placed in the flue gas ducts of power plants, in a cooling tower and in the hood outlet of a paper or board factory. Therefore, the selective membranes must be thermally and chemically stable under the existing environmental conditions and resistant to fouling.

Benefits
> Water recovery > 40%
> Competitive with existing (demin) water production methods
> Minimal energy requirement
> Little to no chemicals required
> Little to no waste produced
> No reheating of flue gas
> Corrosion prevention
> Air treatment: reuse of dehumidified air

Project partners
> 14 partners from 7 countries in 3 continents, including DNV KEMA as project coordinator.

Project details
> EU-funded program
> Duration: September 2010 – August 2013