US3294625A - Method for impregnating cellulosic material - Google Patents

Method for impregnating cellulosic material Download PDF

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Publication number
US3294625A
US3294625A US268623A US26862363A US3294625A US 3294625 A US3294625 A US 3294625A US 268623 A US268623 A US 268623A US 26862363 A US26862363 A US 26862363A US 3294625 A US3294625 A US 3294625A
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United States
Prior art keywords
liquor
pressure
chips
vapor
water vapor
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US268623A
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English (en)
Inventor
Adolf W Gessner
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Lummus Technology LLC
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Lummus Co
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Publication date
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Priority to US268623A priority Critical patent/US3294625A/en
Priority to NO152593A priority patent/NO115239B/no
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Publication of US3294625A publication Critical patent/US3294625A/en
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Expired - Lifetime legal-status Critical Current

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    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
    • D21C1/00—Pretreatment of the finely-divided materials before digesting
    • D21C1/10—Physical methods for facilitating impregnation

Definitions

  • the present invention relates to an improved method for treating cellulosic material, and more particularly, the present invention relates to an improved method for the impregnation of cellulosic material, such as wood chips and the like with cooking liquor.
  • the present invention provides an improved method for impregnating cellulosic material whereby water vapor within the pores of the material is condensed, causing the impregnating liquor to be drawn into the pores of the material.
  • wood chips or the like are introduced into a deaerating vessel to remove air from such material by the introduction of low pressure steam into the vessel.
  • the chips are then passed into an impregnation vessel having a vapor space above the surface of the liquor.
  • the temperature of the liquid in the impregnation vessel is slightly lower than the temperature of the steam introduced into the deaerating vessel, and the total pressure within the impregnation vessel is maintained slightly lower than the pressure in the deaerating vessel.
  • the water vapor within the chips expands to the total pressure in the impregnation vessel as the chips enter and fall through the vapor space in the impregnation vessel.
  • the chips contact the slightly cooler liquor, they are cooled and the water vapor within the chips condenses, thereby forming a lower pressure in the pores of the chips which draws cooking liquor into the pores by the pressure difiFerence.
  • the condensation of water vapor in the pores of the chips occurs at the dew point corresponding to the total pressure in the impregnation vessel. Since the liquor is cooler than the condensation temperature, and since the liquor contains dissolved chemicals, the saturation partial pressure of water vapor above the liquor is appreciably below the total pressure in the impregnation vessel.
  • Air or other non-condensible gases are therefore introduced into the vapor space so that the total pressure in the impregnation vessel is above the equilibrium partial pressure of water vapor above the liquor.
  • the chips when thoroughly impregnated with liquor, have a specific gravity somewhat above that of the liquor, and thus sink beneath the surface of the liquor without mechanical aid.
  • One of the primary objects of the present invention is to provide an improved method of impregnating cellulosic material. with delignifying liquor whereby a more uniform pulp is attained.
  • Another object of the present invention is to provide an improved method of impregnating cellulosic material wherein water vapor in the pores of the cellulosic material is condensed, thereby effecting a lower pressure Within the pores which draws delignifying liquor into the pores of the material.
  • Still another object of the present invention is to provide a method wherein the pores of cellulosic material or the like being impregnated are filled with a delignifying liquor rather than a non-delignifyin-g liquor, such as water, into which the chemicals of the delignifying liquor would have to penetrate by the slower process of diffusion.
  • FIGURE 1 is a diagrammatic view of an apparatus for carrying out the present invention.
  • FIGURE 2 is a vapor pressure vs. temperature diagram illustrating the operating conditions in accordance with the present invention.
  • wood chips or like cellulosic material are passed from a chip supply tank 10 through a star valve 12 or other suitable metering device into a deaerating tank 14.
  • Low pressure steam is introduced through a steam supply line 16, provided with a control valve 18 into the :bottom of the tank 14.
  • a vent line 20 provided with a control valve 22 is in communication with an upper portion of tank 14.
  • Valve 18, controlled by suitable means (not shown) permits steam to be introduced into the tank 14 to subject the chips to the steam pres sure.
  • Valve 22, controlled by suitable means (not shown) permits the air in the tank 14 to be withdrawn when the chips are deaerated by replacing the air within the chips with water vapor.
  • Deaerated chips from tank 14 are withdrawn through -a star valve 24 or other suitable metering device.
  • the chips are subjected to batchwise steaming in tank 14, by sequentially opening and closing the valves 18 and 22, by suitable control means (not shown), so that the chips in the tank are alternate-1y subjected to the steam pressure and then vented to efiFect deaeration and the replacement of air in the chips with water vapor.
  • the deaerated chips withdrawn from the tank 14 are passed into an impregnation vessel, generally designated by reference numeral 26.
  • the liquor level 32 in tank 26 is regulated by suitable liquid level control means (not shown) operatively connected to valve 30 to maintain a vapor space 34 in the top of vessel 26.
  • the pressure in vessel 26 is maintained slightly below the pressure of the deaerating tank 14.
  • the temperature of the cooking liquor in the vessel '26 is maintained slightly below the dew point of water vapor at the total pressure within the vessel 26.
  • an inert gas such as air
  • valve 38 which may be regulated by a suitable pressure or flow con troller 40.
  • Gases may be exhausted from the vapor space through line 42 controlled by valve 44 which is regulated by a pressure controller 46. Controllers 40 and 46 maintain the pressure in vapor space 34 at a pressure slightly lower than the pressure within the tank 14. As the chips fall through the vapor space, the water vapor in the pores of the chips expands thereby preventing air infiltration. The chips then contact the cooking liquor and are cooled causing the water vapor in'the pores .to condense creating a lower pressure within the chips which draws in the cooking liquor. T'he impregnated chips now having a specfic gravity somewhat higher than that of the liquor, sink beneath liquor surface 32, and are subsequently withdrawn as a suspension from vessel 26 through line 48 for subsequent digestion.
  • FIGURE 2 A specific operating example will now be described with reference to the vapor pressure curves of FIGURE 2 wherein the curve A is the partial pressure of water vapor above pure water, and the curve B is the partial pressure of Water vapor above the liquor.
  • the chemicals in the liquor will cause a boiling point elevation of about 3.l F. to 3.5 F.
  • FIGURE 2 is based on a 35 F. boiling point elevation.
  • Wood chips or like cellulosic material are introduced into the deaerating vessel 14 maintained at a pressure of 45 p.s.i.a. Saturated steam at 45 p.s.i.a. is introduced through line 16. The chips leave the deaerating vessel 14 with their pores essentially filled with saturated steam and some steam condensate at 274.4 F. and 45 p.s.i.a. These conditions are indicated by the point F on the curve A in FIGURE 2.
  • the pressure in vapor space 34 is maintained at 40 p.s.i.a., by means of pressure controllers 40 and 46.
  • the temperature of the cooking liquor in impregnation vessel 26 is maintained at 260 F.
  • the partial pressure of water vapor above liquor at this temperature is about 33.4 p.s.i.a.
  • the operating conditions may be varied so long as they are in keeping with the essential features described above including maintaining the total pressure in the vapor space of the vessel 26 below the pressure in the deaerating vessel 14, and to maintain the cooking liquor temperature slightly below the condensation temperature of Water vapor at such total pressure, making up the diiference between the vapor pressure above the cooking liquor and the total pressure by introducing an inert gas, such as air, into the impregnating vessel.
  • an inert gas such as air
  • a process for impregnating wood chips or the like comprising replacing air within the pores of the chips with water vapor in a deaerating zone,
  • a process for impregnating wood chips or the like comprising replacing air within the pores of the chips with water vapor in a deaerating zone,
  • a process for impregnating cellulosic material comprising replacing air within the pores of the material With water vapor in a deaerating zone
  • a process for impregnating cellulosic material comprising replacing air within the pores of the material with water vapor in a deaerating zone
  • a process for impregnating cellulosic material comprising replacing air within the pores of the material with Water vapor in a deaerating zone
  • a process for impregnating cellulosic material comprising replacing air within the pores of the material with water vapor in a deaerating zone

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  • Paper (AREA)
  • Chemical And Physical Treatments For Wood And The Like (AREA)
  • Devices That Are Associated With Refrigeration Equipment (AREA)
US268623A 1963-03-28 1963-03-28 Method for impregnating cellulosic material Expired - Lifetime US3294625A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
US268623A US3294625A (en) 1963-03-28 1963-03-28 Method for impregnating cellulosic material
NO152593A NO115239B (enrdf_load_stackoverflow) 1963-03-28 1964-03-25

Applications Claiming Priority (1)

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US268623A US3294625A (en) 1963-03-28 1963-03-28 Method for impregnating cellulosic material

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US3294625A true US3294625A (en) 1966-12-27

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US (1) US3294625A (enrdf_load_stackoverflow)
NO (1) NO115239B (enrdf_load_stackoverflow)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3446698A (en) * 1965-06-01 1969-05-27 Owens Illinois Inc Method of impregnating and digesting cellulosic materials in a horizontal digestor
US4632729A (en) * 1984-05-01 1986-12-30 Laakso Oliver A Chip presteaming and air washing
WO1998035089A1 (en) * 1997-02-07 1998-08-13 Kvaerner Pulping Ab Method and apparatus for preheating an impregnating cellulosic material
US6109312A (en) * 1999-03-05 2000-08-29 Sawyer; Michael D. Air evacuation insert for wood chip digester

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US68261A (en) * 1867-08-27 Improved process of preparing paper-pulp from straw and other materials
US480334A (en) * 1892-08-09 Hermann xdelbert alfred
US1771598A (en) * 1925-07-11 1930-07-29 Sidney D Wells Process for digesting fibrous material
GB333426A (en) * 1929-09-20 1930-08-14 James Holmes Process of and apparatus for effecting continuous digestion in the extraction of cellulose
US1857432A (en) * 1925-07-08 1932-05-10 Certain Teed Prod Corp Felt
US1859847A (en) * 1926-08-04 1932-05-24 Arthur M Hyde Pulped material and process of preparing the same
US2230119A (en) * 1937-02-18 1941-01-28 Cellulose Res Corp Process of producing wood cellulose
US2640774A (en) * 1953-01-27 1953-06-02 Pulp And Papen Res Inst Of Can Production of cellulose pulp

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US68261A (en) * 1867-08-27 Improved process of preparing paper-pulp from straw and other materials
US480334A (en) * 1892-08-09 Hermann xdelbert alfred
US1857432A (en) * 1925-07-08 1932-05-10 Certain Teed Prod Corp Felt
US1771598A (en) * 1925-07-11 1930-07-29 Sidney D Wells Process for digesting fibrous material
US1859847A (en) * 1926-08-04 1932-05-24 Arthur M Hyde Pulped material and process of preparing the same
GB333426A (en) * 1929-09-20 1930-08-14 James Holmes Process of and apparatus for effecting continuous digestion in the extraction of cellulose
US2230119A (en) * 1937-02-18 1941-01-28 Cellulose Res Corp Process of producing wood cellulose
US2640774A (en) * 1953-01-27 1953-06-02 Pulp And Papen Res Inst Of Can Production of cellulose pulp

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3446698A (en) * 1965-06-01 1969-05-27 Owens Illinois Inc Method of impregnating and digesting cellulosic materials in a horizontal digestor
US4632729A (en) * 1984-05-01 1986-12-30 Laakso Oliver A Chip presteaming and air washing
WO1998035089A1 (en) * 1997-02-07 1998-08-13 Kvaerner Pulping Ab Method and apparatus for preheating an impregnating cellulosic material
US6109312A (en) * 1999-03-05 2000-08-29 Sawyer; Michael D. Air evacuation insert for wood chip digester

Also Published As

Publication number Publication date
NO115239B (enrdf_load_stackoverflow) 1968-09-02

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