Crossflow filtration of green liquor for increased pulp production, improved green liquor quality, and energy savings

• A new green liquor filtration system has been installed and commissioned at the Ence pulp mill in Pontevedra, Spain. The filtration system is based on microfiltration and was developed in collaboration with the KTH Royal Institute of Technology in Stockholm, Sweden. The patented method for efficient purification of green liquor decreases the non-process element (NPE) content by providing more efficient solids/liquid separation, reducing energy and chemical consumption in pulp mills and increasing production capacity by eliminating certain capacity bottlenecks. The process has been continuously tested at the Aspa Bruk Mill outside Askersund, Sweden, since 2013. The technology has proven to create nearly particulate-free green liquor during the purification process. The technology can also be used to polish white liquor to provide higher pulp quality. To provide for a simple and cost-effective installation, the system was designed as a skid-mounted unit that is pre-piped, instrumented, and tested before shipment. The system is modular and allows for easy expansion of capacity. This paper discusses the process design, process integration, and startup of the new system, along with experi-ences from the first months of operation. Application: The patented and trademarked CleanFlow system is a technology designed to increase the capacity of a kraft mill recausticizing plant. Crossflow ceramic membranes are used to filter a portion of the green liquor, debottlenecking the existing green liquor clarifiers’ filters. The liquor quality is improved by reducing the buildup of NPEs. CleanFlow can also be implemented to filter white liquor, either the entire stream for improved pulp quality or just a portion, such as with preparing oxidized white liquor for pulp delignification after cooking, or for scrubbing of bleaching system vents.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Materialteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering (hsv//eng)

TEKNIK OCH TEKNOLOGIER  -- Materialteknik -- Pappers-, massa- och fiberteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering -- Paper, Pulp and Fiber Technology (hsv//eng)

Nyckelord

Ceramic membranes

Cost effectiveness

Delignification

Energy conservation

Microfiltration

Patents and inventions

Purification

Chemical consumption

Cross flow filtration

Increasing production

Non process elements

Process integration

Purification process

Recausticizing plants

Royal Institute of Technology

Pulp cooking

Liquids

Pulp Quality

Systems

Publikations- och innehållstyp

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