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ANDRITZ pre-hydrolysis cooking for dissolving pulp production

The key to dissolving pulp production is efficient removal and recovery of hemi-cellulose from the fiber source. The pre-hydrolysis vessel (PHV) from ANDRITZ is a new technology developed for cost effective production of high quality pulp and valuable by-products.

The challenge

In the production of dissolving pulp, there are unique challenges for hemi-cellulose removal with continuous cooking. Stable production and the precipitation of by-products from the chemical reaction were common difficulties in traditional systems.

The solution

ANDRITZ has re-designed the cooking process to include auto-hydrolysis for efficient hemi-cellulose removal. The process design and technology components are based on experience in paper grade pulping and they eliminate instabilities in previous systems. The design can be easily applied to existing installations.

This new ANDRITZ technology has gained rapid acceptance and is being delivered to several customers in Asia where viscose fiber growth is the highest.

Installation and operational costs are likely to be much lower than traditional dissolving experience. Fiber yields are expected to be several percentage points higher than existing batch technologies, due to better selectivity of the principle reactions and controlled, sustainable recovery of the by-products.

Current practice is for neutralization and burning of the hydro-lysate with the bulk black liquor. However, future development will allow for processing this valuable stream for energy production, further improving the economics of the overall pulping process.

Processes and technologies available from ANDRITZ

  • Diamondback chip pre-steaming
  • TurboFeed chip feeding
  • Pre-hydrolysis treatment
  • Lo-Solids cooking
  • Clean steam technology
  • Hydrolysate treatment
  • Laboratory simulations and investigations

3d model with pre-hydrolysis vessel

ANDRITZ pre-hydrolysis vessel (PHV) selectively removes and recovers hemi-cellulose from wood chips without adding acid.

Cooking process for both kraft and dissolving pulp

Pre-hydrolysis vessel (PHV) can be easily included in a retrofit of an existing facility. Cooking pre-hydrolysis upgrade at Sun Paper Industry Joint Stock Co. , Ltd. in China

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