Pulp and Paper

Doctoring is an important part of the pulp and paper making process with several functions such as removing water and contaminants from the roll surface, cleaning and conditioning the roll surface, and sheet shedding during sheet breaks or threading operations.

A doctoring system consists of the doctor back (i.e., a beam), a doctor blade holder, a doctor blade, and components to mount the system to the machine’s framework. The doctor blade is the component that performs the functions of removing water, debris, and contaminants; cleaning and conditioning the roll surface, or shedding the sheet. Blades are wearing parts   and need to be replaced on a regular basis depending on the application.

Doctoring can prevent material from wrapping the roll surface. In applications where a continuous web of product is being produced such as paper, a web break can cause the material to wrap around the roll. Doctoring systems help direct the product, sheet, or web to the next section of the machine. There are also specialty doctoring applications like creping of the sheet, coating, and metering applications.

Cleaning and conditioning products, such as the M-clean™ system, spray nozzles, stationary and oscillating showers, electro-mechanical shower oscillators, and fabric brush assemblies, are designed to remove contaminants from fabrics, felts, belts, wires, and rolls in process industries including pulp and paper. 

Common applications for cleaning and conditioning systems include roll and doctor lubrication, conveyor and belt cleaning, product knock-off, drying cylinder cleaning, chemical cleaning, high-pressure belt press fabric and cylinder cleaning, drilled suction roll cleaning, and sludge press cleaning.

Filtration products, such as pressure filters and water resource recovery strainers, are used to remove contaminates from liquid in the pulp and paper industry. A filtration system will contain a filter media which is used to separate unwanted particles from the substance being filtered. The filtration process can be intermittent or continuous providing high cleaning efficiency and easy maintenance. 

To maximize performance, filtration systems are chosen and designed for the application. Common applications include fresh water, process water recycling, dyes and additives, mechanical seal protection, chemicals, DAF filtrate, clearleg save-all water, overflow cylinder vat water, vacuum pump seal water, felt hair removal from the press section, fiber recovery from u-drains, solids separation, thickening, fiber scalping, removal of sand from river and lake, water, cooling towers, pump protection, and spray nozzle protection.  

Kadant manufactures water resource recovery strainers, such as the RotoFlex™ resource recovery strainer and gravity strainers, which assist with the filtering, process, and reclaiming of white water. 

Forming refers to a process and a section of a paper machine. The forming section of a paper machine is where the first stage of building the mat of paper takes place. Water and fiber are presented from a nozzle referred to as the headbox onto a moving filter medium known as a forming fabric. 

Forming products are the devices and equipment that support and remove the water throughout the development of the web of paper until it reaches a state that will allow it to transfer to a pressing stage. Forming products consist of forming boards, foil blades, deckles, deckle boards, wear surfaces, low vacuum units, high vacuum units, and top formers.