Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
  • F04D29/00—Details, component parts, or accessories
  • F04D29/08—Sealings
  • F04D29/10—Shaft sealings
  • F04D29/12—Shaft sealings using sealing-rings
  • F04D29/126—Shaft sealings using sealing-rings especially adapted for liquid pumps
  • F04D29/128—Shaft sealings using sealing-rings especially adapted for liquid pumps with special means for adducting cooling or sealing fluid
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21D—TREATMENT OF THE MATERIALS BEFORE PASSING TO THE PAPER-MAKING MACHINE
  • D21D5/00—Purification of the pulp suspension by mechanical means; Apparatus therefor
  • D21D5/26—De-aeration of paper stock
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
  • F04D9/00—Priming; Preventing vapour lock
  • F04D9/04—Priming; Preventing vapour lock using priming pumps; using booster pumps to prevent vapour-lock
  • F04D9/041—Priming; Preventing vapour lock using priming pumps; using booster pumps to prevent vapour-lock the priming pump having evacuating action

Definitions

• This invention relates to a centrifugal pump for pulp suspensions of lignocellulosic material.
• the invention more precisely, relates to a pump where gas, such as air, can be separated from the pulp in the pump.
• Gas following along with the pulp causes problems at pumping by centrifugal pumps.
• the gas in the pulp is collected to bubbles, which are accumulated in front of the impeller and thereby deteriorate the capacity of the pump.
• This problem can be overcome by evacuating the gas from the space in front of the impeller, for example by means of vacuum pumps of the kind of liquid-ring pumps.
• Such a pump can be a separate vacuum pump, the suction pipe of which is connected to the sealing space of the pulp pump, or it can be formed with a separate vacuum impeller in the form of a liquid-ring impeller, which is mounted on the shaft of the pulp pump, so that for both impellers a common operation is obtained.
• the pulp pump becomes relatively complicated and expensive, because the system comprises more components compared to a pulp pump, where the vacuum impeller is mounted on the shaft of the pulp pump.
• SE patent specification 502127 and EP patent specification 298949 describe embodiments of pulp pumps where the vacuum impeller is mounted on the shaft of the pulp pump.
• SE 502127 the control of the capacity of the vacuum pump by adjustable throttling or re-setting the eccentricity of the vacuum pump housing, as shown in SE 502127, several movable parts are required in the pump housing, This requires more or less extreme designs with the risk of faulty functioning. The maintenance, furthermore, will be more complicated and expensive.
• a great amount of air is supplied to a pump system, at which the intention is, that air should be removed therefrom.
• liquid which is required for their function, operation, control and sealing, is supplied separately on both sides of the vacuum pump for the said purposes. This implies two connections for liquid and, on the whole, higher liquid addition.
• the present invention implies that the aforesaid problems can be eliminated.
• the manufacture and maintenance costs for the pulp pump, for example, can be reduced.
• the need of liquid for the operation is decreased, and control and sealing of the vacuum pump can be carried out more simply.
• the need of air to be added to the pump can be reduced substantially.
• the pulp pump is formed with an integrated vacuum pump, where the gas inlet and gas outlet are located on one side of the vacuum pump housing. Only one liquid inlet must be connected to the sealing, which in its turn supplies operational liquid to the vacuum pump.
• Fig. 1 is a cross-section of a centrifugal pump according to the invention
• Fig. 2 shows schematically the coupling between gas inlet and gas outlet to and from the vacuum pump.
• the centrifugal pump shown comprises a pump housing 10 with an inlet 11 and an outlet 12 for the pulp suspension. Such pumps are used at relatively high pulp concentration, for example 6-18%.
• an impeller 14 is mounted, the pump blades 15 of which extend from a hub 16 outward along a wheel disk 17.
• the wheel disk 17 further is formed with openings 19 for the discharge of gas collected in front of the impeller.
• Behind the impeller 14 a vacuum impeller with vacuum impeller blades 20 is located, which impeller is surrounded by a vacuum pump housing 21.
• This vacuum pump housing 21 comprises an outer cylindric wall 22, a rear wall 23 and a front wall 24.
• the cylindric wall 22 is eccentric in relation to the vacuum impeller blades 20, so that a liquid ring pump is formed.
• a suction port 25 for gas and an exhaust port 26 for gas are located in the front wall 24 .
• These ports 25,26 are placed at a distance from each other in the circumferential direction counted for gas suction into the vacuum pump housing and, respectively, gas exhaust from the vacuum pump housing. This effect is brought about in a manner known per se by the rotation of the vacuum impeller blades and the volume variation in the circumferential direction of the vacuum pump housing as a consequence of the eccentric position of the cylindric wall 22.
• the exhaust port 26 communicates with a chamber 27 for gas evacuation through a gas outlet 28.
• a gas passage 29 for communication between the openings 19 in the wheel disk 17 and suction port 25 is located.
• a sealing housing 30 with a shaft sealing 31 for the vacuum pump and pulp pump is located.
• the sealing is intended to be flown through by liquid, which is supplied via a liquid inlet 32.
• the sealing housing 30 communicates also with the vacuum pump housing 21 for the supply of liquid from the sealing to the vacuum pump.
• the liquid amount can be restricted without problems. Only one liquid connection is required.
• the pressure difference arising between the sealing housing 30 and vacuum pump housing implies a barrier for flow in the opposite direction, i.e. only clean water will be found in the surrounding of the sealing.
• the suction port 25 and exhaust port 26 of the vacuum pump housing are in controllable connection with each other, for example via an overflow channel 35 with a device 36 for vacuum control.
• this control device 36 the connection between the suction and exhaust side can be controlled without the use of air addition from the outside in order to prevent that pulp suspension is sucked into the vacuum pump, if the pressure would be much too low. Instead of air addition from the outside, thus, a portion of the air is used which already has been sucked out of the pulp pump for the control. This implies a pump system with less air flows.
• the control device 36 can be a valve in the overflow channel 35, for example of the kind on/off, a throttle valve or the like.
• the control device can be controlled by signals from the system in a suitable way known per se.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Structures Of Non-Positive Displacement Pumps (AREA)
• Applications Or Details Of Rotary Compressors (AREA)
• Paper (AREA)
• Diaphragms For Electromechanical Transducers (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (1)

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ID=20284996

Family Applications (1)

Country Status (6)

Families Citing this family (7)

Citations (7)

Family Cites Families (9)

• 2001
  • 2001-08-08 SE SE0102678A patent/SE519641C2/sv not_active IP Right Cessation
• 2002
  • 2002-07-08 DE DE60238538T patent/DE60238538D1/de not_active Expired - Lifetime
  • 2002-07-08 WO PCT/SE2002/001358 patent/WO2003014572A1/en not_active Application Discontinuation
  • 2002-07-08 EP EP02763142A patent/EP1415094B1/en not_active Expired - Lifetime
  • 2002-07-08 AT AT02763142T patent/ATE491094T1/de active
  • 2002-07-08 US US10/485,976 patent/US20050053496A1/en not_active Abandoned

Patent Citations (8)

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