Providing vacuum pumps that make paper at less cost and higher quality.
Black Liquor Evaporation
Located in the pulp mill, the black liquor evaporator concentrates the black liquor obtained during the pulp washing process so that the liquor can be used in a recovery furnace to reclaim chemicals for re-use in the pulping process. The liquid ring vacuum pump is used to aid in the evaporation process.
Brown Stock Washers
Brown stock washers remove the pulping chemicals (or "black liquor") from the raw paper stock prior to bleaching or other stock preparation processes. The brown stock washer is typically a horizontal, rotating drum filter with a vacuum created on the drum's interior. As the filter rotates into the stock, the vacuum allows the stock to adhere to the outer surface of the drum and assists in removing (or "washing") the black liquor from the stock.
Lime Mud & Precoat Filters
Located in the pulp mill, lime mud filters recover the lime used in the white liquor clarification process. Similar to the brown stock washer, a lime mud filter is typically a horizontal, rotating drum filter with a vacuum on the drum's interior. As the filter rotates into the lime mud, a "cake" of lime is formed on the drum's exterior surface. It is then doctored off and reused in the white liquor process.
Located in the pulp mill, the dregs filter removes non-combustible suspended particles; carbon particles from incomplete combustion; iron compounds; and pieces of furnace refractory lining (i.e. "dregs") from the "green" liquor before causticizing. The dregs filter is typically a horizontal, rotating drum filter with a vacuum on the interior used to extract the particulate from the green liquor.
Deckers are used in the stock preparation process for thickening the stock. The decker is typically a rotating, horizontal, drum filter that removes proportionate amounts of water from the pulp to increase the consistency of the stock.
Stock and Whitewater Deaeration Systems
Stock and whitewater deaeration systems are used in the stock preparation process to remove any entrained air from the stock or from the dilution water prior to entering the headbox. Stock deaeration systems are important because they remove air from the paper stock, which causes pinholes in the sheet, and ultimately effects printability, mechanical properties and overall sheet quality.
Dearation systems typically use a two-stage vacuum system with the inlet to the first stage vacuum pump at stock boiling point (27-28 in HgV) and the second stage pump inlet pressure sized for a 4:1 compression ratio between the first stage inlet. A precondenser is typically used between the dearation vessel and the first stage vacuum pump and a small interstage separator is required between the first and second stage vacuum pumps. Standard materials of construction are used for each vacuum pump.
Headbox Compressor/Vacuum Pump
Used in "airpadded" headboxes, headbox compressor/vacuum pumps create a pressure/vacuum above the stock level (or "pond" level) in the headbox to ultimately control the velocity by which the stock exits the headbox ("jet" velocity) onto the moving wire.
Vacuum Pumps are usually configured to operate as both vacuum pumps and compressors through a series of valves. They either create a vacuum or a pressure in the void volume above the pond level to control the static head in the headbox.