Classifications

• • C—CHEMISTRY; METALLURGY
  • C14—SKINS; HIDES; PELTS; LEATHER
  • C14B—MECHANICAL TREATMENT OR PROCESSING OF SKINS, HIDES OR LEATHER IN GENERAL; PELT-SHEARING MACHINES; INTESTINE-SPLITTING MACHINES
  • C14B1/00—Manufacture of leather; Machines or devices therefor
  • C14B1/58—Drying
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06B—TREATING TEXTILE MATERIALS USING LIQUIDS, GASES OR VAPOURS
  • D06B15/00—Removing liquids, gases or vapours from textile materials in association with treatment of the materials by liquids, gases or vapours
  • D06B15/09—Removing liquids, gases or vapours from textile materials in association with treatment of the materials by liquids, gases or vapours by jets of gases
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F26—DRYING
  • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
  • F26B5/00—Drying solid materials or objects by processes not involving the application of heat
  • F26B5/04—Drying solid materials or objects by processes not involving the application of heat by evaporation or sublimation of moisture under reduced pressure, e.g. in a vacuum
  • F26B5/045—Drying solid materials or objects by processes not involving the application of heat by evaporation or sublimation of moisture under reduced pressure, e.g. in a vacuum for drying thin, flat articles in a batch operation, e.g. leather, rugs, gels

Definitions

• the present invention relates to a system for creating a vacuum in a multi-layer tanning dryer, according to the general definition in claim 1.
• a "vacuum” dryer comprises a range of heated levels on which the wet skins are spread. These are then closed with a “lid” cover in order to form a drying chamber, inside which a vacuum is then created to accelerate the evaporation of the liquid substances contained in said skins, substances which are transformed into gases and vapours .
• these dryers comprise a system for heating the levels and a system to create the vacuum in the drying chambers on the various levels.
• the system is basically composed of one or more suction units, defined by the term "vacuum pump", which suck in the gases and vapours from the drying chamber and the condensers, located upstream of the aforesaid pumps, and which are used to cool part of the vapours until they are condensed.
• vacuum pump which suck in the gases and vapours from the drying chamber and the condensers, located upstream of the aforesaid pumps, and which are used to cool part of the vapours until they are condensed.
• a drawback that arises with this type of system is represented by the fact that when the damp gaseous substances (gases and vapours released by the drying skins) are sucked in by the liquid ring or vane pumps, they mix with the working fluids (the water or oil that must ensure the hermetic sealing and lubrication of moving parts) , to form a strongly corrosive polluting mixture that provokes rapid deterioration of the vanes and other components of the aforesaid pumps, thus requiring constant maintenance and creating considerable running costs.
• the working fluids the water or oil that must ensure the hermetic sealing and lubrication of moving parts
• said polluting mixture (the lubrication fluids necessary for liquid ring or vane vacuum pump operation, plus the gases and vapours released in the hermetically sealed vacuum chamber during skin drying action, and that are sucked out because of vacuum action) cannot be discharged directly into the sewer system because it would provoke strong pollution, and therefore the system must also be equipped with a separator.
• the object of the present invention is to create a vacuum system that eliminates the aforesaid problems, in other words, that does not result in the emission of polluting substances such as emulsified oil and polluted water that require complex and expensive processing; in particular, during skin drying operations, the system must release vapours and gases that, when condensed, can be easily collected and taken to disposal plants.
• a further aim of the invention is to create a vacuum system that is able to provide very strong suction and reduced pressure performance levels, with power consumption, which is considerably lower than that of prior art.
• blowers familiarly known by the term “Roots blower”
• Rooms blower are very simple to build, and have the added advantage of not requiring lubricants that come into contact with the gaseous substances to be compressed, as occurs with liquid ring or vane pumps, and therefore they do not generate polluting mixtures and thus prevent the problems described above.
• the system is characterised in that it involves a circuit positioned downstream of the vacuum condenser, inside which at least two 3-lobed Roots blowers are inserted. These are better known as vacuum pumps with pre-inlet and a heat exchanger with condensation recovery.
• the system according to the invention can be possibly completed with a third 2-lobed Roots blower, better known as a vacuum blower, set between the vacuum condenser and the aforesaid circuit. Said Roots blower operation is controlled by a by-pass valve.
• a third 2-lobed Roots blower better known as a vacuum blower
• the system is completed with suitable auxiliary equipment such as at least one gaseous substance collector tank, a silencer with a suction filter on environment inlet, and a silencer on the fume discharge.
• suitable auxiliary equipment such as at least one gaseous substance collector tank, a silencer with a suction filter on environment inlet, and a silencer on the fume discharge.
• the two Roots blower vacuum pumps are positioned in series and their suction ratio is approximately 5:1; the first Roots blower vacuum pump is positioned with the suction opening for cooling at pre-inlet in communication with the environment, and therefore the absolute pressure at the suction opening is approximately 200 mbar.
• the second Roots blower vacuum pump is positioned upstream and in series with the first Roots blower, and therefore its suction opening pre-inlet communicates with the reduced pressure pipe at 200 mbar, and because of the suction ratio of 5:1, the absolute pressure at its suction opening is approximately 40 mbar.
• the delivery opening of the aforesaid is connected by means of a second pipe to said first pipe, which is the inlet pipe for the suction opening of the first Roots blower.
• a heat exchanger is inserted into the second pipe, to provide for the condensation of the vaporised liquids present in the gases sucked in from the vacuum chamber, as well as for cooling the fluid.
• a third two-lobed Roots blower is activated in the connecting pipe between the second Roots blower and the vacuum condenser, which when activated by a by-pass valve, and working together with the other two Roots blower, will provide a final vacuum level lower than 2mbar.
• running mode which means that this occurs when the vacuum chambers are hermetically sealed and the system operates with the highest possible vacuum level.
• the third blower is excluded and the flow rate of the fluid sucked in from the machine and discharged by the second Roots blower is subdivided by the two aforesaid pipes into a first part which is sucked in by said second Roots blower, and necessary for said Roots blower to operate, and the remaining part in excess, which is sucked in by the first Roots blower and expelled into the atmosphere.
• the self-balancing differential in the suction by the two Roots blowers is gradually reduced with the progressive increase of the vacuum in the circuit, and it will finally disappear when the second Roots blower begins operating at its maximum differential pressure, in other words, when the absolute suction pressure returns to approximately 40 mbar, as opposed to an inlet/discharge pressure of approximately 200 mbar.
• Figure 1 shows a layout of the system applied to a multi-level vacuum dryer.
• the system according to the invention is connected to a condenser "K”, into which are directed the vacuum intakes of the various levels of the vacuum "S” by means of on-off valves "V”, and which is basically composed of three Roots blowers, identified by numerals 1, 2 and 3, of a by-pass valve 4, a heat exchanger 5, equipped with a silencer with a suction filter 7, and a silencer mounted on the gaseous substance discharge 8, said devices being connected by means of piping as specified further on.
• a condenser "K” into which are directed the vacuum intakes of the various levels of the vacuum "S” by means of on-off valves "V”, and which is basically composed of three Roots blowers, identified by numerals 1, 2 and 3, of a by-pass valve 4, a heat exchanger 5, equipped with a silencer with a suction filter 7, and a silencer mounted on the gaseous substance discharge 8, said devices being connected by means of piping as specified further on.
• Roots blowers 1 and 2 are three-lobe types, better known as pre-inlet vacuum pumps, while Roots blower 3, is a two-lobe vacuum blower.
• Figure 1 shows the two Roots vacuum pumps 1 and 2 positioned reciprocally in series, since their suction ratio is 5:1, and since the first Roots vacuum pump 1 is positioned with the suction opening for cooling at the pre- inlet, in communication with the environment, it has an absolute pressure of approximately 200 mbar in its suction opening "A" .
• the second Roots blower is positioned upstream and in series with the first Roots blower 1, and therefore results as having the pre-inlet suction opening in communication through a first connection pipe 10, with a zone in reduced pressure at 200 mbar. Therefore because of the ratio 5:1, it has an absolute pressure of approximately 40 mbar in its suction opening "B".
• the delivery opening In order to permit the Roots blower 2 to operate with an absolute pressure of 40 mbar at the suction opening inlet, in relation to a pressure of 200 mbar, the delivery opening must be connected by a second pipe 20 to the aforesaid first connection pipe 10, inside which a heat exchanger 5 has been inserted, and equipped with a condensate discharge tank 6.
• a possible third Roots blower 3 can operate, activated by a by-pass valve 4 and working together with the other two Roots blowers 1 and 2. This will produce a final vacuum level in the circuit that is lower than 2 mbar .

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Manufacturing & Machinery (AREA)
• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Textile Engineering (AREA)
• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Molecular Biology (AREA)
• General Engineering & Computer Science (AREA)
• Applications Or Details Of Rotary Compressors (AREA)
• Drying Of Solid Materials (AREA)

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• 2006
  • 2006-07-27 IT IT000240A patent/ITVI20060240A1/it unknown
  • 2006-12-04 EP EP06818970A patent/EP2049695B1/fr not_active Not-in-force
  • 2006-12-04 DE DE602006019152T patent/DE602006019152D1/de active Active
  • 2006-12-04 BR BRPI0621571-8A patent/BRPI0621571A2/pt not_active IP Right Cessation
  • 2006-12-04 AT AT06818970T patent/ATE492655T1/de not_active IP Right Cessation
  • 2006-12-04 WO PCT/EP2006/011599 patent/WO2008011912A1/fr active Application Filing
  • 2006-12-04 KR KR1020087026816A patent/KR20090034304A/ko not_active Application Discontinuation

Non-Patent Citations (1)

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