Kamyr, Inc.

Ahlstrom Machinery, Inc.

Louis O Torregrossa

J Robert Prough

C Bertil Stromberg

Joseph R Phillips

Brian F Greenwood

Ake Backlund

Mark D Barrett

J Wayne Chamblee

Todd S Grace

Vic L Bilodeau

Patrick E Sharpe

Gary L McCarty

Gunther Plattner

Recycled paper pulp having at least two different types of paper which consume widely different amounts of bleaching chemical, or mixed hardwood and soft-wood pulps, are treated in a manner that enhances distribution and redistribution of bleaching chemical to enhance uniformity of the bleaching treatment. The pulp is intensely mixed to provide a homogenous mixture of fibrous material and bleaching chemical, and then is continuously or intermittently subjected to mechanical action (such as in low intensity mixers, or by agitating pulp in a retention tank) of sufficient intensity and duration so as to enhance distribution and redistribution of a bleaching chemical. Also, recycled pulp will have cleanliness which varies significantly over time, and this is accommodated by sensing at least one of the brightness, color, or lignin content (e.g. all three) of the pulp prior to treatment in a first bleaching stage, controlling the quantity of first bleaching chemical added to the first stage in response to at least one of the brightness, color, or lignin content sensing to achieve a target brightness increase for the first stage, and then repeating the sensing and quantity control steps for a second and subsequent stages. Alternatively all sensing can be done initially. Within a stage, a valve may be controlled to subject the pulp to a second treatment in that stage, or to pass it out of the stage to the next stage, depending upon cleanliness.

Bleaching cellulose pulp having cleanliness which varies significantly

A number of different, efficient treatments of slurries and liquid with gas can be provided. A slurry or liquid is introduced into a first end of a vortex. A gas--such as a chemically reactive gas--is introduced from exteriorly of the vortex into contact with the slurry or liquid in the vortex, so that a desired reaction between the slurry or liquid and the gas takes place. The treated slurry or liquid is removed from the second end of the vortex while any residual or carrier gas is removed from the first end of the vortex. Gas introduction is preferably accomplished through a porous surface of revolution (e.g. cylindrical or conical) wall surrounding the vortex, the gas being in minute bubble form when it enters the slurry or liquid. This has particular applicability in the treatment of paper pulp using an ozone containing gas, or in reacting various liquids in the paper and pulp industry with gas (such as reaction of caustic solutions with chlorine or chlorine dioxide gas), the stripping of a strippable component from a liquid (e.g. stripping black liquor soap from black liquor, using air), or absorbing an absorbable component in a gas into a liquid (such as absorbing ozone, chlorine, or the like in water), or scrubbing furnace flue gases. Gas may also optionally be removed from adjacent the second end of the vortex through a separate conduit from the gas being removed from the first end of the vortex.

Method of chemically reacting a slurry with a gas

Liquid process streams--such as white water, pressate, or washer filtrate from a pulp and paper mill--are clarified in an efficient manner using a gas sparged hydrocyclone, which takes up a minimum of floor space. A liquid stream having a consistency of less than about 0.5% solids is introduced into a first end of a vortex. Gas is sparged into the liquid in the vortex to cause particles to attach to gas bubbles and move through a rejects outlet at the first end of the vortex, while clarified liquid is removed from a second end of the vortex. A pedestal is typically provided at the accepts outlet, having a radial clearance with the inside of a porous tube through which the gas is sparged that is about 8-12% the radius of the porous tube.

Clarifying suspended solids from liquid process streams

A slurry or liquid is introduced into a first end of a vortex. A gas--such as a chemically reactive gas--is introduced from exteriorly of the vortex into contact with the slurry or liquid in the vortex, so that a desired reaction between the slurry or liquid and the gas takes place. The treated slurry or liquid is removed from the second end of the vortex while any residual or carrier gas is removed from the first end of the vortex. Gas introduction is preferably accomplished through a porous surface of revolution (e.g. cylindrical or conical) wall surrounding the vortex, the gas being in minute bubble form when it enters the slurry or liquid. This has particular applicability in the treatment of paper pulp using an ozone containing gas, or in reacting various liquids in the paper and pulp industry with gas (such as reaction of caustic solutions with chlorine or chlorine dioxide gas), the stripping of a strippable component from a liquid (e.g. stripping black liquor soap from black liquor, using air), or absorbing an absorbable component in a gas into a liquid (such as absorbing ozone, chlorine, or the like in water), or scrubbing furnace flue gases.

Method of chemically reacting a liquid with a gas in a vortex

Biomass, such as bagasse, is pre-hydrolyzed, to ultimately effect hydrolysis of hemicellulose to sugars. Biomass is mixed with a mineral acid solution to form a slurry having a consistency of about 8 to 12% so that the acid solution properly wets the biomass. Then the slurry is dewatered to about 35 to 50% consistency, and is heated to reaction temperature (e. g. about 320.degree. F.) by direct contact with steam in the vapor phase of a vertical pressurized reactor, having a pressure of about 40 psig. A fluffer is preferably provided in the top of the reaction vessel. After a reaction time of about 30 minutes, the biomass is diluted and cold blown out of the bottom of the reactor. Pressate from the dewatering has acid added to it and is heated by indirect heat exchange with a sugar solution obtained by washing of the biomass discharged from the reactor, and is then mixed with the biomass as the acid solution.

Acid pre-hydrolysis reactor system

Organic constituents in a liquid, such as a waste water from a municipal or industrial process (e.g. bleach plant extraction liquor from the bleaching of paper pulp) may proceed effectively without the addition of alkali. When the organic constituents are reacted with an oxygen containing gas at appropriate pressure and temperature conditions, oxidized organics and gaseous acidic products of oxidation (e.g. CO.sub.2) that are produced are continuously and immediately removed from the liquid so that they do not significantly contribute to lowering of the pH of the liquid, so that the reaction may proceed and the liquid remain alkaline. This may be accomplished in a gas sparged hydrocyclone in which the liquid is introduced into the first end of a vortex while oxygen is introduced from exteriorly of the vortex into contact with the liquid, or may be accomplished by causing the liquid to flow in a thin film in a downwardly extending spiral path and removing the acidic gases from a center portion of the spiral path. A reactor for effecting the last mentioned specific procedure includes a pressurized vertical vessel having a downwardly extending stationary spiral surface mounted in the vessel substantially concentric with it. Surface manifestations may be provided on the spiral surface for enhancing mixing of liquid with surrounding gas.

Reactor having a discontinuous conduit means between surfaces of a

A hydrocyclone establishes a first vortex of fluent material at one end (e.g. in a top portion), and a second vortex at the other end (e.g. in a bottom portion). The first vortex is established within a porous surface of revolution to which gas or other fluid is supplied, passing through the porous surface into the first vortex. The second vortex is established by a conical end section extending outwardly from (e.g. below) the porous surface, and with an axial (e.g. bottom) discharge for fluent material. Some fluent material--for example having heavy particles--is removed tangentially from the conical end section at a portion near the porous surface of revolution. A conical shroud having a circumferential periphery is mounted by a number of spaced legs connected between the shroud and the conical bottom section so that fluent material may pass between the circumferential periphery of the shroud and the porous surface of revolution. An axial gas passage is provided in the shroud to allow gas to escape from the second vortex into the first vortex, and ultimately out the first end (e.g. top) of the hydrocyclone. A plenum surrounding the porous surface of revolution may be divided into two or more axial portions, and liquid can be introduced into one of the plenum portions so that it experiences a pressure drop as it passes through the porous surface of revolution, thereby causing small bubbles to form.

Gas sparged centrifugal device

Method and apparatus for reducing contamination in processed pulp and in white water effluent discharged from a pulp dryer or paper making mill. The system includes multiple pulp bleaching and washing stages wherein white water effluent discharge from the dryer or paper making mill is fed to the next-to-last washing stage and fresh water is supplied to the last washing stage.

Method for reducing contamination in pulp processing

The latency of mechanical pulp is removed in a quick and simple manner. After refining of comminuted cellulosic material to produce mechanical pulp, the pulp is diluted (if necessary) to a consistency of between about 8-25%, and the pulp is then merely pumped to a further treatment stage. Pumping is effected utilizing a centrifugal pump which fluidizes the pulp, the fluidization imparting sufficient energy to the pulp to remove the latent properties. The pulp may be pumped to a storage stage prior to passage to a screening stage, and can be pumped in a direct (non-return) path from the pump to the screening stage. If desired or necessary, a portion of the pumped pulp can be recirculated and pumped again to ensure that sufficient energy is imparted thereto to effect latency removal.

Method of removing latency from medium consistency pulps by pumping the

A mixer apparatus, and procedure, for mixing medium consistency (e.g., 6-15%) paper pulp, or like fibrous suspension, minimizes the power necessary to effect fluidization, and minimizes the speed for rotation of the rotor to effect fluidization. This is accomplished by preventing the formation of a shadow behind the rotor ribs as they rotate within the mixer housing, and similarly by preventing the formation of a shadow behind the stationary ribs formed on the housing (and cooperating with the rotating ribs). Such shadows are prevented by providing one wall of each of the ribs--the trailing wall in the direction of rotation of the rotor--so that it is sloped, and fills the volume the shadow would occupy.

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Glens Falls, NY, United States of America

Louis O Torregrossa