US Patent 11015292 Process and apparatus for wetlaying nonwovens

A process and an apparatus for producing nonwoven materials are disclosed. The process comprises the following steps: a) providing a three-phase (gas-liquid-solid) suspension containing air, water, fibrous material and a surfactant, b) depositing the suspension onto a moving carrier sieve to produce a fibrous web on the carrier, c) removing aqueous residue of the suspension through the carrier sieve, d) conveying the aqueous residue through one or more phase separation tanks in an essentially horizontal direction while providing a depressurised headspace above the aqueous residue, e) recycling the aqueous residue conveyed in step d) to step a), f) preferably pre-integrating the fibrous web.