No. 99 Yilan Rd., Xiamen , CN.
+86 186 5928 0806

Shell Plate Rolling Services for Pulp Digester

Over 400 tons of rolled shell plates successfully export to Laos. These shell plates are used in the manufacture of 8 digesters. The digester is 17 meters high and with a diameter of 5.8 meters and 10.5 meters. Each digester requires 14 shell plates, a total of 112 pieces, with a total weight of 400 tons.

shell plate rolling for digester

The digester is a large tower container that needs to be assembled and welded at the construction site, and the digester is the main equipment for paper pulping.

What is pulp digester?

Pulp digester or digester, is a large vessel for chemical pulping and dissolved fiber steaming section. As we all know, the raw materials of paper pulp like grasses, bamboo, wood and other sources are cooked in the digester. These raw materials react with a chemical liquid and get the paper pulp, which is mostly composed of cellulose. The paper pulp, can then be sent to washing bleaching system and applied to paper making processing. There are two types of digester in the chemical pulping productions, for the different pulping processing - vertical digester and horizontal digester. The vertical digester is used mostly for the super batch cooking. The most advanced batch-cooking technology -displacement cooking process is usually adopted, as it requires low cost and high-quality pulp is obtained. Different raw materials like 316L steel, carbon steel, stainless steel, duplex stainless steel, and composite plate are used in making of the digester series.

Main Steps of Paper Pulp Processing

Paper pulp processing refers to the production activity of paper pulp by mechanical or chemical processing method. It can be generally divided into the following main steps:
Wood storage → Wood sawing → Debarking and Knotting→ Wood cutting for chips→Cooking→Washing→Screening and Purifying→Unbleached pulp (or→ Bleaching→Bleached pulp) →Soaking and Refining

Paper mill digester is used for the cooking process. The cooking process is an important step in the pulp processing process. It is a complex chemical process. It is to send the plant fiber raw material after the mechanical pretreatment into the digester with chemical cooking liquor under high temperature and pressure for further treatment. The lignin and other impurities will be dissolved and removed. Finally, the chemical pulp is obtained. The purpose of the cooking process is to remove the lignin in the fiber raw material, retain cellulose and hemicellulose and dissociate the fibers into the required pulp by using chemical agents according to the needs of different types of pulps.

Digester classification

Digester can be divided into batch type and continuous type:

  • The batch digester can be also divided into vertical type or horizontal type of cylindrical and spherical pressure vessels. Both are heated with steam.
    The vertical digester is commonly known as bog pot. It has a larger capacity. It is a fixed device and usually attached to liquor circulation equipment. The spherical digester is commonly known a steam ball. It has a smaller capacity and is a rotary device.
  • Continuous digester includes tube type and vertical type. It is equipped with an automatic metering device and control equipment. It is a new type of digester and suitable for the caustic soda method, sulfate method or semi-chemical method to produce wood pulp, straw pulp and so on.

What Do We Do For Papermaking with Our Metal Fabrication and Machining Services?

Key steel fabrication services that we perform for pulp and paper making companies, OEMs and equipment manufacturing firms include plate bending, mechanical engineering, manufacturing of wear-resistant components, ASME pressure vessel fabricationheat exchanger constructionplate rolling, plate forming, metal forming, cold forming, hot forming, steel plate fabrication, weldingheat treatingplate cutting, and plate straightening. We have the capabilities, industry experience and specialized equipment needed to form, cut, machine, process and join most types of heavy steel, alloy steel or metal.

Openex offers metal fabrication for pulp and paper mills that includes products, such as:

  • Heavy Structures
  • Yankee Dryer
  • Stands and Racks
  • Safety Platforms and Walkways
  • Safety Fencing
  • Material Handling Equipment
  • Scanning Frame
  • Sink
  • Cladding Parts
  • Impeller
  • And more!

Contact us at or call us at +86 186 5928 0806 for more information about fabrication for pulp and paper making and to receive a free project quote today.

About Openex

Openex is home to a full-service, one-stop-shop, contract manufacturing company producing custom large machined parts and fabrications. Our full large fabrication services including large machining, cutting, welding, rolling, punching, braking, testing, painting, and others.
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