Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
  • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
  • F17C7/00—Methods or apparatus for discharging liquefied, solidified, or compressed gases from pressure vessels, not covered by another subclass
  • F17C7/02—Discharging liquefied gases
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B26—HAND CUTTING TOOLS; CUTTING; SEVERING
  • B26F—PERFORATING; PUNCHING; CUTTING-OUT; STAMPING-OUT; SEVERING BY MEANS OTHER THAN CUTTING
  • B26F3/00—Severing by means other than cutting; Apparatus therefor
  • B26F3/004—Severing by means other than cutting; Apparatus therefor by means of a fluid jet
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
  • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
  • F17C2201/00—Vessel construction, in particular geometry, arrangement or size
  • F17C2201/01—Shape
  • F17C2201/0104—Shape cylindrical
  • F17C2201/0109—Shape cylindrical with exteriorly curved end-piece
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
  • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
  • F17C2201/00—Vessel construction, in particular geometry, arrangement or size
  • F17C2201/01—Shape
  • F17C2201/0104—Shape cylindrical
  • F17C2201/0119—Shape cylindrical with flat end-piece
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
  • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
  • F17C2201/00—Vessel construction, in particular geometry, arrangement or size
  • F17C2201/01—Shape
  • F17C2201/0138—Shape tubular
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
  • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
  • F17C2223/00—Handled fluid before transfer, i.e. state of fluid when stored in the vessel or before transfer from the vessel
  • F17C2223/01—Handled fluid before transfer, i.e. state of fluid when stored in the vessel or before transfer from the vessel characterised by the phase
  • F17C2223/0146—Two-phase
  • F17C2223/0153—Liquefied gas, e.g. LPG, GPL
  • F17C2223/0161—Liquefied gas, e.g. LPG, GPL cryogenic, e.g. LNG, GNL, PLNG
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
  • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
  • F17C2223/00—Handled fluid before transfer, i.e. state of fluid when stored in the vessel or before transfer from the vessel
  • F17C2223/03—Handled fluid before transfer, i.e. state of fluid when stored in the vessel or before transfer from the vessel characterised by the pressure level
  • F17C2223/035—High pressure (>10 bar)
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
  • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
  • F17C2223/00—Handled fluid before transfer, i.e. state of fluid when stored in the vessel or before transfer from the vessel
  • F17C2223/03—Handled fluid before transfer, i.e. state of fluid when stored in the vessel or before transfer from the vessel characterised by the pressure level
  • F17C2223/036—Very high pressure (>80 bar)
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
  • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
  • F17C2227/00—Transfer of fluids, i.e. method or means for transferring the fluid; Heat exchange with the fluid
  • F17C2227/01—Propulsion of the fluid
  • F17C2227/0128—Propulsion of the fluid with pumps or compressors
  • F17C2227/0157—Compressors
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
  • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
  • F17C2227/00—Transfer of fluids, i.e. method or means for transferring the fluid; Heat exchange with the fluid
  • F17C2227/03—Heat exchange with the fluid
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
  • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
  • F17C2250/00—Accessories; Control means; Indicating, measuring or monitoring of parameters
  • F17C2250/04—Indicating or measuring of parameters as input values
  • F17C2250/0404—Parameters indicated or measured
  • F17C2250/0439—Temperature

Definitions

• the present invention relates to an installation and a method of cutting by cryogenic fluid jet.
• This cutting process is similar to cutting processes using a high-pressure water jet or a jet of fluid loaded with abrasive particles. It has the advantage of not moistening the cut material, which is particularly advantageous for cutting food, or hydrophilic materials. Furthermore, the boiling point of cryogenic fluids is generally significantly below 0 ° C at atmospheric pressure. The process is therefore particularly suitable for cutting frozen products.
• French Patent No. 2,647,049 describes a process for cutting materials with a fluid, maintained under low pressure in a tank, and compressed at high pressure to form a jet which volatilizes after cutting the material.
• the object of the present invention is to improve this process, in particular by increasing the efficiency of cutting.
• the invention relates more particularly to a cryogenic fluid jet cutting installation comprising a storage tank for cryogenic liquid at low pressure, a high-pressure compressor, an ejection nozzle connected by heat-insulating ducts, as well as a heat exchanger. heat disposed between the storage tank and the ejection nozzle for cooling the ejected fluid to a constant set temperature.
• the functioning 1 heat exchanger is slaved to the signal delivered by a temperature sensor disposed at the inlet of the high-pressure compressor.
• This embodiment guarantees the permanence of the mechanical efficiency of the jet.
• the heat exchanger is arranged between the storage tank and the high-pressure compressor.
• the heat exchanger consists of an enclosure containing liquid nitrogen connected to a vacuum pump causing the expansion of the liquid nitrogen contained in said enclosure.
• the heat exchanger comprises a primary circuit in which the cryogenic fluid circulating coming from the storage tank, said primary circuit being thermally connected to a secondary circuit in which circulates a fluid coming from a cryogenerator.
• the heat exchanger is controlled by an electronic circuit connected to the temperature sensor disposed at the inlet of the high-pressure compressor, and comprising an adjustment means for the adjustment of a set point value fixed experimentally.
• the electronic circuit includes a comparator, one of the inputs of which receives the signal from the temperature sensor and the other inverter input receives a setpoint voltage from the means for adjusting the setpoint temperature.
• the invention also relates to a method of cutting by jet of cryogenic fluid compressed to a pressure greater than 500 bars and ejected through a calibrated orifice of small diameter.
• the set temperature is determined experimentally cryogenic fluid at the inlet of the high-pressure compressor by optimizing the mechanical efficiency of the jet, and in that the temperature of the cryogenic fluid is kept equal to the set value by a controlled temperature exchanger.
• Another object of the invention is to allow industrial cutting of a plurality of elements.
• Cutting a part involves the relative displacement of the ejection nozzle relative to the part.
• connection between the high pressure pump and the nozzle is carried out by a high pressure resistant conduit, articulated in a manner avoiding deformation.
• patent PS3631116 consists in that the duct is movable in rotation around the Z axis thanks to a spiral element and a joint. It explicitly aims to avoid transverse deformations of the high-pressure resistant tube by using a conformation of the duct in the form of a spiral.
• This document PS363111 ⁇ does not disclose the characteristic relating to the insulation of the duct, which is not very compatible with a spiral conformation, unless it results in excessive congestion of the cutting system and an unacceptable gap between the different nozzles.
• a second object of the invention is to remedy these drawbacks by allowing multi-cutting with a high performance cryogenic jet.
• the invention relates more particularly to an installation in which the outlet of the high-pressure compressor is connected to a fixed ramp constituted by a tubular duct with thick insulating wall, to which is connected at least one tubular duct with thick insulating wall whose end opposite to the ramp is secured to a movable plate in a plane substantially perpendicular to the longitudinal axis of said conduit, the ejection nozzle being connected to the movable end of said conduit.
• a plurality of thick-walled conduits is connected to the fixed ramp, the end of each of said conduits being integral with a movable plate in a plane substantially perpendicular to the longitudinal axis of said conduit, a nozzle ejection being connected to each of the movable ends of said conduits.
• the thick-walled conduits are surrounded by a sealed envelope, the volume between the sealed envelope and the conduit being connected to a vacuum pump.
• each of the ejection nozzles is fixed to the plate so as to maintain a constant ejection direction whatever the position of said plate.
• FIG. 1 shows a schematic view of the installation according to the invention
• FIG. 2 shows an embodiment of an electronic circuit for controlling the heat exchanger
• FIG. 4 shows a schematic view of a variant of the installation according to the invention
• FIG. 5 shows a schematic view of the installation according to the invention
• FIG. 6 shows a sectional view of the cryogenic fluid ejection system.
• This installation comprises a storage tank (1) for liquid nitrogen at low pressure and at a temperature corresponding substantially to the boiling temperature, ie at 77.3 ° K at atmospheric pressure.
• the temperature of liquid nitrogen increases during storage by about 0.5 ° per day due to the heat losses resulting from the lack of insulation.
• This reservoir (1) is constituted by a cylindrical body with thick walls closed by flanges.
• This tank is connected via a heat-insulating duct (2) to an intermediate tank (3) of smaller capacity.
• a valve (4) allows the filling of the intermediate tank (3) to be controlled.
• This reservoir (5) of gaseous nitrogen makes it possible to raise the pressure of the liquid nitrogen contained in the intermediate reservoir (3) until a sufficient pressure is reached for the booster of the high-pressure compressor which follows. Conventionally, the booster pressure is around 30 bars.
• the booster pressure is around 30 bars.
• the valve (7) disposed at the outlet of the intermediate tank is closed during this time.
• the valve (4) disposed at the inlet of the intermediate tank (3) is closed and the valve (6) connecting the liquid nitrogen tank (5) to the intermediate tank is opened. ).
• the pressure of liquid nitrogen in the intermediate tank (3) thus increases up to the booster pressure.
• the outlet valve (7) can then be opened to start a high-pressure compression cycle.
• the intermediate tank (3) is connected to a temperature exchanger (8) supplied with low temperature primary fluid by a cryogenerator (9), for example helium stirling, or by expansion of liquid nitrogen.
• a cryogenerator (9) for example helium stirling, or by expansion of liquid nitrogen.
• This temperature exchanger (8) has the function of lowering the temperature of liquid nitrogen to a temperature below the boiling temperature, and of regulating the temperature of nitrogen supplying the high-pressure compressor. It is connected to the high-pressure compressor (12) by a pipe (10) provided with a thermally insulated valve (11).
• a temperature sensor (31) measures the temperature of the cryogenic fluid at the inlet of the high-pressure compressor (12).
• the signal delivered by the temperature sensor (31) is compared to a setpoint signal delivered by an adjustment device (32) by an electronic circuit (33).
• This electronic circuit (33) controls the operation of the temperature exchanger (8) so as to keep the temperature of the cryogenic fluid supplying the high-pressure compressor (12) constant and equal to the set temperature.
• the high-pressure compressor (12) consists of a pressure intensifier using a double-acting piston, having a head
• the piston consists of a plunger (15) of reduced section, communicating with a chamber (18) supplied with liquid nitrogen at low pressure.
• the outlet of the booster (12) feeds an ejection nozzle (19) comprising in a known manner a sapphire pierced by a calibrated orifice.
• the ejection head
• FIG. 2 represents an exemplary embodiment of an electronic circuit (33). It is composed of a differential operational amplifier (35) one of the inputs of which receives the signal from of the temperature sensor (31) and the other input of which is connected to a variable resistor (36) delivering a setpoint signal. The output of the operational amplifier (35) is connected to a power stage (36) controlling the operation of the engine of the cryogenerator.
• a differential operational amplifier (35) one of the inputs of which receives the signal from of the temperature sensor (31) and the other input of which is connected to a variable resistor (36) delivering a setpoint signal.
• the output of the operational amplifier (35) is connected to a power stage (36) controlling the operation of the engine of the cryogenerator.
• the setting of the set temperature is carried out as follows:
• a standardized sample for example a plate made of a reference material, and of a standardized thickness, is placed on the cutting tray.
• the sample is then moved under the jet and the target value is modified by acting empirically on the control means
• the temperature for liquid nitrogen in equilibrium with the vapor phase is 77.35 ° K.
• the cycle would be isentropic, and would correspond to the vertical line AA ', the path AA' representing the isentropic compression without any exchange with the outside at the level of the body of the booster (12), and the path A'A representing the nitrogen jet outlet isentropic liquid, without exchange with the outside at the nozzle (19).
• each transformation leads to an increase in entropy.
• a point B ' In order to obtain an outlet jet corresponding to a mixture of vapor phase and liquid phase, represented on the temperature-entropy diagram by a point B ', it is necessary to take account of the exchanges and therefore to set the initial operating point at a point C of the liquid-vapor separation curve corresponding to an initial temperature lower than the boiling temperature.
• the compression in the booster (12 ) is represented by the path CD, reflecting an increase in entropy by loss due to the heat exchanges between the nitrogen and the wall of the booster (12).
• the expansion occurring at the nozzle (19) is represented by the path DB showing the thermal losses due to rolling.
• the vapor pressure is less than 1 bar, and the ejected fluid is therefore completely liquid, with no vapor phase.
• the operating point C of the nitrogen introduced into the booster is adjusted so that the operating point B "at the outlet of the nozzle (19) is very slightly beyond the equilibrium point corresponding to a temperature of 77.3 ° K at atmospheric pressure, so that the fluid has a proportion of gaseous phase between 1 and 20% by volume.
• the fluid will thus behave like a charged liquid bubbles producing a mechanical erosion effect on contact with the material to be cut. Maintaining the optimum operating point B "will be obtained by controlling the cooling temperature by the temperature exchanger (8).
• FIG. 4 shows an alternative embodiment of the installation.
• the liquid nitrogen is cooled before entering the booster (12) by circulation in an enclosure (41) containing liquid nitrogen coming from the storage tank (1).
• This enclosure is connected to a vacuum pump (42) creating a vacuum causing expansion of the liquid nitrogen, and therefore a lowering of the temperature.
• a pressure of 0.3 bar causes the temperature to drop by 8 °.
• the temperature sensor (31) delivers a signal to an electronic circuit (33) also receiving a signal from a means for adjusting (32) the set value.
• the output of the electronic circuit (33) controls the operation of the vacuum pump, as well as the operation of a valve disposed between the vacuum pump (42) and the enclosure (41).
• FIGS. 5 and 6 relate to an alternative embodiment of a multi-nozzle cryogenic jet cutting installation.
• the nozzle (69) is supplied with cryogenic fluid under pressure through a thick-walled conduit (74).
• This conduit is constituted by a stainless steel tube having an internal diameter of 1.6 millimeters and an external diameter of 6.35 millimeters.
• the pipe (74) is surrounded by an insulating sleeve connected to the liquid nitrogen tank (53) by a pipe (72) insulated by an insulation sleeve (73).
• the upstream end (75) of the duct (74) connecting the booster (62) to the nozzle (69) is fixed.
• the opposite end closest to the nozzle (69) is movable in a plane perpendicular to the longitudinal axis to the conduit (74).
• a motor (77) mounted on a frame (not shown) causes the nozzle (69) to move in a direction perpendicular to the plane of the figure.
• the elasticity of the conduit (74) allows a lateral movement whose amplitude depends on the length of the conduit
• a duct made of stainless steel allows lateral movement of the movable end of approximately 50 millimeters for a length of 80 centimeters.
• the workpiece (80) is moved in a direction perpendicular to the axis of the jet and to the direction of movement of the nozzle (69) via a conveyor (81), for example a roller conveyor.
• a conveyor for example a roller conveyor.
• the combination of the two movements makes it possible to follow any cutting line.
• FIG. 6 represents a view of the ejection system comprising several ejection nozzles (90 to 93).
• the outlet of the booster (112) is connected to a supply ramp (94).
• This feed ramp consists of a plurality of tubular segments (95 to 98).
• the tubular segments (95 to 98) are connected together in a known manner.
• Each of the tubular segments (95 to 98) has a branch opening into a conduit (99 to 102) supplying one of the nozzles (90 to 93) with high pressure cryogenic fluid.
• Each of the conduits (99 to 102) is surrounded by a bellows envelope (103 to 106), opening onto the sleeve (107 to 110) surrounding the corresponding tubular segment (95 to 98).
• the nozzles (90 to 93) are integral with a plate (111) supporting the drive mechanisms (112 to 115).
• the plate (111) is fixed relative to the ramp (94).
• the drive mechanism (112 to 115) ensures the lateral displacement of the corresponding nozzle (90 to 93), and therefore causes a deformation of the corresponding conduit (99 to 102).
• the nozzle (92) disposed at the end of the conduit (101) is moved to the right, which causes a longitudinal deformation of the conduit (101) of which the two ends retain the original orientation.
• the upstream end remains perpendicular to the horizontal plane passing through the ramp (94).
• the downstream end remains perpendicular to the plate (111).
• the intermediate part of the conduit (101) takes a regular curvature determined by the mechanical characteristics of the material constituting the conduit.
• conduit (102) is deformed in the opposite direction due to the displacement of the corresponding nozzle (93) to the right.
• the material to be cut (116) is moved in the plane parallel to the plate (111) by a conveyor (117).
• the device shown in Figure 6 allows for four simultaneous cutting lines.
• the control of the drive mechanisms (112 to 115) of the nozzles (90 to 93) as well as of the conveyor (117) can be controlled by a computer, optionally controlled by the cutting speed.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Life Sciences & Earth Sciences (AREA)
• Forests & Forestry (AREA)
• Perforating, Stamping-Out Or Severing By Means Other Than Cutting (AREA)

Applications Claiming Priority (5)

Publications (1)

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ID=26230222

Family Applications (1)

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Family Cites Families (11)

• 1994
  • 1994-03-31 JP JP52176094A patent/JPH08511205A/ja active Pending
  • 1994-03-31 EP EP94912580A patent/EP0691901A1/de not_active Withdrawn
  • 1994-03-31 WO PCT/FR1994/000369 patent/WO1994022646A1/fr not_active Application Discontinuation

Non-Patent Citations (1)

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