CN118490335A - Supercritical fluid output device and method for cryoablation system - Google Patents
Supercritical fluid output device and method for cryoablation system Download PDFInfo
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Abstract
The invention provides a supercritical fluid output device and a supercritical fluid output method for a cryoablation system, wherein the output device comprises a liquid nitrogen storage container and at least two supercritical fluid output branches arranged in parallel in the liquid nitrogen storage container, and the supercritical fluid output branches arranged in parallel are converged outside the liquid nitrogen storage container to form a supercritical fluid output trunk; each output branch comprises a conveying device, a generator and a heat exchanger which are sequentially connected, and a heating device is arranged in the generator. According to the output device, through the design of a plurality of parallel branches in the storage container, and the generators, the heat exchangers and the like are arranged on the branches, the temperature of the fluid is regulated after liquid nitrogen is formed into supercritical fluid, so that the cold energy which can be provided by the liquid nitrogen is ensured, gasification is avoided, and the controllable regulation and output of the pressure and flow of the supercritical fluid are realized; when the output device is used for cryoablation, different working modes can be adopted to meet the requirements under different application scenes, and the output device is high in safety and good in treatment effect.
Description
Technical Field
The invention belongs to the technical field of cryoablation, and relates to a supercritical fluid output device and method for a cryoablation system.
Background
Cryoablation is a process of freezing or destroying abnormal cells or pathological tissues by using a low-temperature freezing medium, and is used for treating various tumors and arrhythmia, and atrial fibrillation is one of the most common arrhythmia at present, and is gradually a controllable and curable disease along with the development of medicine and catheter ablation technology. The freezing working medium used in the cryoablation technology comprises a gas-phase working medium and a liquid-phase working medium, wherein when the gas-phase working medium is used, the working pressure of the cryoablation system is very high, and the design of the intervention consumable is subjected to severe limiting conditions, so that the liquid-phase freezing working medium is usually selected preferentially at present.
When the freezing saccule is used for treating paroxysmal atrial fibrillation, the freezing controller conveys the liquid freezing working medium into the freezing saccule through the injection pipeline, and the liquid freezing working medium is gasified when in heat exchange with the surrounding tissue of the pulmonary vein on the outer wall of the saccule, so that a large amount of heat is taken away, the tissue is frozen and damaged, and the pulmonary vein isolation effect is achieved. The liquid-phase freezing working medium used at present mainly comprises liquid nitrous oxide and liquid nitrogen, the temperature of the liquid nitrous oxide cannot be reduced to be low enough, the carrying cold quantity is limited, the required ablation time is long, the radiation exposure quantity is increased, the liquid-phase freezing working medium can provide higher cold quantity, but the liquid-phase freezing working medium is easy to gasify when heated, so that the system cannot work normally, and researchers try to adopt supercritical fluid at present, and the safety of the system operation is improved by utilizing the characteristics of the supercritical fluid, namely the viscosity of gas and the density of liquid.
When the refrigeration working medium is adopted for cryoablation at present, the output cold quantity cannot be controlled and regulated generally, and unsuitable cold quantity can not only increase atrial muscle injury, but also increase the probability of operation complications. CN107307901a discloses a cryoablation system comprising a catheter, a fluid delivery unit and a control unit; the catheter comprises a central cavity and a balloon positioned at the distal end of the catheter, wherein an input channel for inputting cooling fluid into the balloon and an outflow channel for outputting the cooling fluid from the balloon are arranged in the central cavity; the fluid delivery unit supplies and discharges a cooling fluid; the control unit controls the fluid delivery unit. The cryoablation system is mainly used for conveying frozen working medium in a conduit after the frozen working medium is output from a container, and does not relate to control of parameters such as pressure, flow and the like during outputting of the frozen working medium, and related equipment or structures are not designed.
CN 102310516a discloses a supercritical fluid injection device, which consists of a gas cooling pre-pressing part, a supercritical fluid forming part, a pressure, temperature and flow feedback part and a control part, wherein the pressure, flow and temperature feedback part consists of two pressure sensors, two temperature sensors and a counter, and the pressure, temperature and flow control part consists of a microcontroller and a solid relay. The device is mainly used for introducing the formation process of the supercritical fluid, the pressure and the flow rate of the supercritical fluid are controlled in the formation process of the supercritical fluid, the state of the supercritical fluid is not regulated any more, so that the cold energy can be controlled when the supercritical fluid is used for cryoablation, and the use and the connection of related equipment are not related naturally.
In summary, for the application of using supercritical fluid as a freezing medium in a cryoablation process, a proper device is designed according to the supercritical fluid characteristics of the freezing medium, so that the supercritical freezing medium can realize controllable output of parameters such as flow and pressure of the supercritical freezing medium, is suitable for different working occasions, and ensures safety and stability of the treatment process.
Disclosure of Invention
Aiming at the problems existing in the prior art, the invention aims to provide a supercritical fluid output device and a supercritical fluid output method for a cryoablation system, wherein the output device is used for realizing controllable regulation and output of pressure and flow of liquid nitrogen by regulating the temperature of the fluid after the liquid nitrogen is formed into the supercritical fluid through the design of a plurality of parallel branches in a storage container, can meet the working modes in different application scenes when being used for cryoablation, and achieves better treatment effect on the premise of safety.
To achieve the purpose, the invention adopts the following technical scheme:
In one aspect, the invention provides a supercritical fluid output device for a cryoablation system, the output device comprises a liquid nitrogen storage container and at least two supercritical fluid output branches arranged in parallel in the liquid nitrogen storage container, wherein the supercritical fluid output branches arranged in parallel are converged outside the liquid nitrogen storage container to form a supercritical fluid output trunk; each output branch comprises a conveying device, a generator and a heat exchanger which are sequentially connected, and a heating device is arranged in the generator.
In the invention, the supercritical fluid is used in the field of cryoablation, and by utilizing the characteristics of the supercritical fluid, not only can sufficient cold energy be provided, but also no air lock phenomenon can be caused; according to the invention, by structural design of the supercritical fluid output device, a plurality of parallel branches are arranged in the liquid nitrogen storage container, and equipment such as a generator, a heat exchanger and the like are arranged on the branches, so that the liquid nitrogen is heated and gasified under a closed condition, the pressure is increased to form the supercritical fluid, the temperature is reduced through heat exchange, and the cold energy which can be provided by the supercritical fluid is ensured; through the design of a plurality of branches, the output pressure and the flow of the supercritical fluid are controllably regulated to meet different applications and requirements, and the dosage of the frozen working medium is convenient to regulate during cryoablation, so that the safety is high and the treatment effect is good.
The following technical scheme is a preferred technical scheme of the invention, but is not a limitation of the technical scheme provided by the invention, and the technical purpose and beneficial effects of the invention can be better achieved and realized through the following technical scheme.
As a preferred embodiment of the present invention, the supercritical fluid output branch is provided with 2 to 4, for example, 2, 3 or 4, preferably 2.
Preferably, the delivery device is a micropump.
According to the invention, the micro pump is adopted, so that the conveying amount of liquid nitrogen can be accurately measured, meanwhile, the excessive volume of the storage container is prevented from being occupied, and the space utilization rate of the storage container is improved; meanwhile, the invention adopts a low-pressure micro pump, and the lift pressure is slightly higher than the pressure in the liquid nitrogen storage container, so that the requirements can be met.
Preferably, a first one-way valve is also arranged between the conveying device and the generator.
As a preferable technical scheme of the invention, a vacuum heat insulation layer is arranged in the wall surface of the generator.
The thickness of the vacuum insulation layer is preferably 0.1 to 3mm, for example, 0.1mm, 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm, or 3mm, but is not limited to the recited values, and other values not recited in the numerical range are equally applicable.
Preferably, the materials on two sides of the vacuum heat insulation layer comprise stainless steel or aluminum alloy.
According to the invention, the generator is provided with the vacuum heat insulation layer, so that the inside of the generator and the liquid nitrogen storage container can be insulated, the heat exchange between the generator and the liquid nitrogen storage container is effectively reduced, and the energy utilization rate of the heating device is improved.
Preferably, the heating means comprises a resistive wire or an electromagnetic induction heater.
In the invention, when the heating device selects the resistance wire, the resistance wire is directly contacted with fluid to convert electric energy into heat energy; electromagnetic induction heating mode can be adopted to convert electromagnetic energy into electric energy, and the electric energy is converted into heat energy to realize heating.
Preferably, a temperature sensor is also arranged in the generator.
As a preferable technical scheme of the invention, the heat exchanger is in a coil pipe structure or a fin pipe structure.
Preferably, a second one-way valve and a three-way electromagnetic valve are sequentially arranged on a pipeline behind the heat exchanger, and the three-way electromagnetic valve is positioned outside the liquid nitrogen storage container.
In the invention, the three-way electromagnetic valve is opened according to the working state of the branch, one of the two outlets is connected to the supercritical fluid output trunk, and the other outlet can release residual gas in the generator after the output of the supercritical fluid output branch is finished.
Preferably, a pressure sensor is arranged on the supercritical fluid output dry path.
In another aspect, the present invention provides a method for outputting a supercritical fluid using the supercritical fluid output apparatus, the method comprising the steps of:
(1) Delivering liquid nitrogen to a generator for heating and vaporization, and forming liquid nitrogen supercritical fluid after expansion and pressurization;
(2) Conveying the liquid nitrogen supercritical fluid obtained in the step (1) to a heat exchanger, exchanging heat with liquid nitrogen in a liquid nitrogen storage container to obtain cooled supercritical fluid, and introducing the cooled supercritical fluid into a supercritical fluid output trunk;
(3) The opening and closing of different supercritical fluid output branches are controlled to regulate the flow and pressure of the supercritical fluid output trunk.
According to the invention, liquid nitrogen is used as a raw material, supercritical properties of the liquid nitrogen are researched, and the research is used as a basis for preparing critical liquid nitrogen, a supercritical pressure-temperature phase diagram of the liquid nitrogen is shown in figure 1, and the state changes of pressure and temperature in the whole system are described; as can be seen from fig. 1, the critical pressure Pc of liquid nitrogen is 3.4MPa, the critical pressure Pc of liquid nitrogen in the present invention points to a region, which is called a critical pressure region, the range of the region is between 0.8Pc and 1.2Pc, the physical properties of liquid nitrogen in the region are close to those of liquid nitrogen under the critical pressure of 3.4MPa, and the critical temperature corresponding to the critical pressure in fig. 1 is-147 ℃;
as can be seen from fig. 1, 6 states exist in the preparation and application process of the supercritical fluid, 1 is the initial state of the liquid nitrogen under the normal pressure of 0.1 MPa; 2 is the state of the liquid nitrogen after being boosted and is in a critical pressure area; 3 is the state of the pressurized liquid nitrogen after passing through the temperature reduction, namely the output phase point of the liquid nitrogen storage container, and the process is the content related to the invention;
The following 4-6 is a process of supercritical fluid for cryoablation, 4 is a state when the fluid passes through the transmission pipeline and reaches the distal end of the consumable (state change is caused by system pressure loss and pipeline heat leakage); 5 is a state that the liquid phase component is completely gasified after the supercritical fluid (gas-liquid mixed fluid) is fully heat exchanged at the distal end of the consumable; and 6 is that the gas returns to the state of atmospheric pressure through the return gas channel (is directly discharged into the environment).
As a preferable technical scheme of the invention, the liquid nitrogen in the step (1) is normal pressure liquid nitrogen and is stored in a liquid nitrogen storage container.
In the invention, the liquid nitrogen storage container is a low-pressure storage container, compared with the existing common self-pressurization storage container, the evaporation capacity can be reduced, the energy utilization rate is further improved, the low-pressure storage container is adopted to prepare high-pressure fluid, and the problem that the output pressure is unstable because the pressurization rate existing in the self-pressurization storage container is difficult to keep up with the output rate of the fluid is distinguished, and the low-pressure storage container can output continuous fluid with stable pressure.
Preferably, the liquid nitrogen of step (1) is fed into the generator using a micropump.
Preferably, the delivery pressure of the micropump is 0.1 to 1MPa, for example, 0.1MPa, 0.2MPa, 0.3MPa, 0.4MPa, 0.5MPa, 0.6MPa, 0.8MPa, or 1MPa, etc., but the present invention is not limited to the values recited, and other values not recited in the range are equally applicable.
Preferably, the heating mode in the generator in the step (1) is resistance wire heating or electromagnetic induction heating.
In the invention, the resistance wire belongs to an electric heating element, and current passes through the electric heating element to enable the electric heating element to generate heat first, and then the heat is transferred to low-temperature fluid in contact with the electric heating element.
Preferably, after the liquid nitrogen is heated and vaporized in the step (1), the pressure in the generator reaches 3.4-4.0 MPa, such as 3.4MPa, 3.5MPa, 3.6MPa, 3.7MPa, 3.8MPa, 3.9MPa or 4.0MPa, etc., but the method is not limited to the recited values, and other non-recited values in the range are equally applicable; the temperature is above-147 ℃, for example-145 ℃, -142 ℃, -140 ℃, -138 ℃, -135 ℃ or-130 ℃, etc., but is not limited to the recited values, and other non-recited values within the range of values are equally applicable.
As a preferred technical scheme of the invention, the supercritical fluid of liquid nitrogen in the step (2) is cooled to-196 to-170 ℃ after heat exchange with liquid nitrogen, for example-196 ℃, -193 ℃, -190 ℃, -185 ℃, -180 ℃, -175 ℃ or-170 ℃, etc., but the supercritical fluid is not limited to the listed values, and other non-listed values in the range of values are equally applicable.
Preferably, the pressure after the supercritical fluid heat exchange of liquid nitrogen in step (2) is 3.3 to 3.95MPa, for example, 3.3MPa, 3.4MPa, 3.5MPa, 3.6MPa, 3.7MPa, 3.8MPa, 3.9MPa or 3.95MPa, etc., but is not limited to the values recited, and other non-recited values within the range are equally applicable.
In the invention, the liquid nitrogen is heated and gasified by the generator, the pressure of the formed supercritical fluid reaches above the critical pressure, and is in ideal condition infinitely close to the upper limit of the adjacent pressure, namely 1.2Pc, and then the supercritical fluid is subjected to heat exchange with the liquid nitrogen storage container by the heat exchanger, so that the temperature of the supercritical fluid is reduced as close to the nitrogen liquefaction temperature of-196 ℃ as possible, and the pressure of the output fluid is slightly reduced but still in the critical pressure area.
Preferably, in the step (2), the pipeline from the heat exchanger to the supercritical fluid output trunk is controlled by setting a three-way electromagnetic valve to introduce fluid into the supercritical fluid output trunk.
As a preferable technical scheme of the invention, the supercritical fluid output branch in the step (3) has at least two branches, and the output branches are opened simultaneously or part of branches are opened alternately.
Preferably, the working mode that the supercritical fluid output branch is simultaneously opened is mainly used for superficial ablation, and treatment is completed after one-time operation.
In the invention, the N branches are assumed, and for some superficial ablations, the working mode that the N branches are simultaneously opened can be adopted so as to pursue larger flow, the treatment can be completed by running the device once, and N depends on the flow required by the front end.
As a preferable technical scheme of the invention, the working mode that a plurality of supercritical fluid output branches are alternately opened is suitable for the situation that treatment cannot be completed by one-time operation, and the flow rate of the control fluid tends to be constant or alternately changed; the cryoablation is performed at a deeper treatment depth or longer treatment time than the superficial ablation, and the treatment cannot be completed in one operation.
Preferably, when two supercritical fluid output branches are arranged, one branch is opened, the other branch is closed, the output flow is constant, and the pressure fluctuates between the pressure of the output branch and the monitoring pressure of the output trunk.
As a preferred technical scheme of the present invention, when three supercritical fluid output branches are provided, one of the working modes includes: and when the output trunk circuit is reduced to the monitoring pressure, one branch circuit is closed, and the other branch circuit is opened, so that the circulation is realized, and the output flow is kept constant.
Preferably, when three supercritical fluid output branches are provided, another operation mode includes: one branch is opened, when the output trunk is reduced to the monitoring pressure, a second branch is opened, at the moment, the output flow is doubled, when the output trunk is reduced to the monitoring pressure again, the first branch is closed, at the moment, the output flow is reduced to the initial flow, when the output trunk is reduced to the monitoring pressure again, a third branch is opened, at the moment, the output flow is doubled, and the output flow is alternately changed in a sub-circulation mode.
Compared with the prior art, the invention has the following beneficial effects:
(1) According to the output device, through the design of a plurality of parallel branches in the storage container, and equipment such as a generator, a heat exchanger and the like are arranged on the branches, the temperature of fluid is regulated after liquid nitrogen is formed into supercritical fluid, so that the cold energy which can be provided by the liquid nitrogen is ensured, gasification is avoided, and the controllable regulation and output of the pressure and flow of the supercritical fluid are realized;
(2) When the output device is used for cryoablation, different working modes can be adopted to meet the requirements in different application scenes, and the output device is high in safety and good in treatment effect.
Drawings
FIG. 1 is a supercritical pressure-temperature phase diagram of liquid nitrogen in the present invention;
Fig. 2 is a schematic structural view of a supercritical fluid output apparatus for a cryoablation system provided in embodiment 1 of the present invention;
fig. 3 is a schematic structural diagram of a supercritical fluid output apparatus for a cryoablation system provided in embodiment 2 of the present invention;
the device comprises a 1-liquid nitrogen storage container, 2-conveying equipment, a 3-first one-way valve, a 4-generator, a 5-heating device, a 6-temperature sensor, a 7-heat exchanger, an 8-second one-way valve, a 9-three-way electromagnetic valve and a 10-pressure sensor;
FIG. 4 is a graph showing the variation of the supercritical fluid output branch pressure, the output main pressure and the main flow rate provided in example 3 of the present invention;
FIG. 5 is a graph showing the variation of the supercritical fluid output branch pressure, the output main pressure and the main flow rate provided in example 4 of the present invention;
FIG. 6 is a graph showing the variation of the supercritical fluid output branch pressure, the output main pressure and the main flow rate provided in example 5 of the present invention;
Fig. 7 is a graph showing the variation of supercritical fluid output branch pressure, output main pressure and main flow rate according to example 6 of the present invention.
Detailed Description
For better illustrating the present invention, the technical scheme of the present invention is convenient to understand, and the present invention is further described in detail below. The following examples are merely illustrative of the present invention and are not intended to represent or limit the scope of the invention as defined in the claims.
The following are exemplary but non-limiting examples of the invention:
Example 1:
The embodiment provides a supercritical fluid output device for a cryoablation system, the structure schematic diagram of the output device is shown in fig. 2, the device comprises a liquid nitrogen storage container 1 and two supercritical fluid output branches arranged in parallel in the liquid nitrogen storage container 1, and the supercritical fluid output branches arranged in parallel are converged outside the liquid nitrogen storage container 1 to form a supercritical fluid output trunk; each output branch comprises a conveying device 2, a generator 4 and a heat exchanger 7 which are sequentially connected, and a heating device 5 is arranged in the generator 4.
The delivery device 2 is a micropump.
A first one-way valve 3 is also arranged between the conveying device 2 and the generator 4.
A vacuum heat insulation layer is arranged in the wall surface of the generator 4; the thickness of the vacuum heat insulation layer is 1mm.
The materials of the two sides of the vacuum heat insulation layer are stainless steel.
A temperature sensor 6 is also arranged in the generator 4.
The heating device 5 is an electromagnetic induction heater.
The heat exchanger 7 is in a coil structure.
The pipeline behind the heat exchanger 7 is sequentially provided with a second one-way valve 8 and a three-way electromagnetic valve 9, and the three-way electromagnetic valve 9 is positioned outside the liquid nitrogen storage container 1.
The supercritical fluid output dry path is provided with a pressure sensor 10.
Example 2:
The embodiment provides a supercritical fluid output device for a cryoablation system, the structure schematic diagram of the output device is shown in fig. 3, the device comprises a liquid nitrogen storage container 1 and three supercritical fluid output branches arranged in parallel in the liquid nitrogen storage container 1, and the supercritical fluid output branches arranged in parallel are converged outside the liquid nitrogen storage container 1 to form a supercritical fluid output trunk; each output branch comprises a conveying device 2, a generator 4 and a heat exchanger 7 which are sequentially connected, and a heating device 5 is arranged in the generator 4.
The delivery device 2 is a micropump.
A first one-way valve 3 is also arranged between the conveying device 2 and the generator 4.
A vacuum heat insulation layer is arranged in the wall surface of the generator 4; the thickness of the vacuum heat insulation layer was 2.5mm.
The materials of the two sides of the vacuum heat insulation layer are aluminum alloy.
A temperature sensor 6 is also arranged in the generator 4.
The heating device 5 is a resistance wire.
The heat exchanger 7 is in a finned tube structure.
The pipeline behind the heat exchanger 7 is sequentially provided with a second one-way valve 8 and a three-way electromagnetic valve 9, and the three-way electromagnetic valve 9 is positioned outside the liquid nitrogen storage container 1.
The supercritical fluid output dry path is provided with a pressure sensor 10.
The supercritical fluid output apparatus of the above embodiment includes a combination of a plurality of devices, and the structure or type of the generator, the heat exchanger and the heating apparatus is not limited to the fixed combination, that is, the combination of the structures in embodiment 1 and embodiment 2, except for the difference in the number of branches of the supercritical fluid output, for example, the generator, the heat exchanger and the like in embodiment 2 are equally applicable to the liquid nitrogen storage container in embodiment 1.
Example 3:
The present embodiment provides a supercritical fluid output method for a cryoablation system, the output method being performed using the output apparatus of embodiment 1, comprising the steps of:
(1) The liquid nitrogen is conveyed to a generator 4 by a micro pump to be heated and vaporized, the liquid nitrogen is normal pressure liquid nitrogen and is stored in a liquid nitrogen storage container 1, the heating mode in the generator 4 is electromagnetic induction heating, after expansion and pressurization, the pressure in the generator 4 reaches 3.8MPa, and the temperature reaches-140 ℃ to form liquid nitrogen supercritical fluid;
(2) Conveying the liquid nitrogen supercritical fluid obtained in the step (1) to a heat exchanger 7, exchanging heat with liquid nitrogen in a liquid nitrogen storage container 1 to obtain cooled supercritical fluid, wherein the temperature of the supercritical fluid is minus 195 ℃ and the pressure is 3.75MPa, and introducing the supercritical fluid into a supercritical fluid output trunk;
(3) Controlling the alternate opening and closing of the two supercritical fluid output branches to regulate the flow and pressure of the supercritical fluid output trunk;
The specific control process is as follows: firstly, defining the fluid pressure output by a generator in each supercritical fluid output branch as Pm, wherein the fluid pressure output by the generator in each branch cannot be completely the same and is less than but infinitely close to 1.2Pc, so that in an actual branch pressure change curve, pm of each branch is not necessarily equal, and the following embodiment assumes that Pm is a constant value; the monitoring pressure Pn, pn of the supercritical fluid output trunk is defined to be also positioned in the critical pressure area and smaller than the Pm value;
for the working mode of alternately opening the multiple branches, it is assumed that M of the N branches are simultaneously opened, M is determined by the flow Q required by the treatment end, and N-M is more than or equal to 1.
In this embodiment, n=2, m=1, and the change curves of the supercritical fluid output branch pressure, the output main pressure and the main flow are shown in fig. 4; as can be seen from fig. 4, when the pressure of the output trunk drops to Pn, branch 1 is closed, branch 2 is opened, and similarly, branch 2 is closed, branch 1 is opened, thereby cycling, ensuring a constant flow output and q=q, and the pressure fluctuates between Pn and Pm.
Example 4:
The present embodiment provides a supercritical fluid output method for a cryoablation system, the output method being performed using the output apparatus of embodiment 2, comprising the steps of:
(1) The liquid nitrogen is conveyed to a generator 4 by a micro pump to be heated and vaporized, the liquid nitrogen is normal pressure liquid nitrogen and is stored in a liquid nitrogen storage container 1, the heating mode in the generator 4 is resistance wire heating, after expansion and pressurization, the pressure in the generator 4 reaches 4.0MPa, and the temperature reaches-145 ℃ to form liquid nitrogen supercritical fluid;
(2) Conveying the liquid nitrogen supercritical fluid obtained in the step (1) to a heat exchanger 7, exchanging heat with liquid nitrogen in a liquid nitrogen storage container 1 to obtain cooled supercritical fluid, wherein the temperature of the supercritical fluid is-190 ℃, the pressure is 3.9MPa, and introducing the supercritical fluid into a supercritical fluid output trunk;
(3) Controlling the alternate opening and closing of the three supercritical fluid output branches to regulate the flow and pressure of the supercritical fluid output trunk;
in this embodiment, the working mode is also a working mode in which multiple branches are alternately opened, n=3, m=2, and the change curves of the supercritical fluid output branch pressure, the output main pressure and the main flow are shown in fig. 5;
As can be seen from fig. 5, branch 1 and branch 2 are simultaneously open, where q=2q, branch 1 is closed and branch 3 is open when the output trunk pressure drops to Pn, and similarly, branch 1 is open when branch 2 is closed, thereby cycling, ensuring a constant flow output and q=2q, and the output trunk pressure fluctuates between Pn and Pm but is smaller than the fluctuation range in example 3.
Example 5:
The present embodiment provides a supercritical fluid output method for a cryoablation system, the output method being performed using the output apparatus of embodiment 2, comprising the steps of:
(1) The liquid nitrogen is conveyed to a generator 4 by a micro pump to be heated and vaporized, the liquid nitrogen is normal pressure liquid nitrogen and is stored in a liquid nitrogen storage container 1, the heating mode in the generator 4 is resistance wire heating, after expansion and pressurization, the pressure in the generator 4 reaches 3.6MPa, and the temperature reaches-142 ℃ to form liquid nitrogen supercritical fluid;
(2) Conveying the liquid nitrogen supercritical fluid obtained in the step (1) to a heat exchanger 7, exchanging heat with liquid nitrogen in a liquid nitrogen storage container 1 to obtain cooled supercritical fluid, wherein the temperature of the supercritical fluid is-180 ℃ and the pressure is 3.6MPa, and introducing the supercritical fluid into a supercritical fluid output trunk;
(3) Controlling the alternate opening and closing of the three supercritical fluid output branches to regulate the flow and pressure of the supercritical fluid output trunk;
in this embodiment, the working mode is also a working mode in which multiple branches are alternately opened, in which more stable main-path output pressure is pursued, n=3, m is alternately changed between 1 and 2, and the change curves of the supercritical fluid output branch pressure, the output main-path pressure and the main-path flow are shown in fig. 6;
As can be seen from fig. 6, first, the branch 1 is opened, and the output branch pressure change curve is equal to the output main pressure change curve, q=q; when the pressure of the output main circuit is reduced to Pn, opening the branch circuit 2, and increasing the pressure of the output main circuit, wherein the pressure change curve of the output main circuit is equal to the mixed pressure change curve of the branch circuit 1 and the branch circuit 2, and Q=2q; when the pressure of the output main circuit falls to Pn again, the branch circuit 1 is closed, the pressure of the output main circuit rises, the pressure change curve of the output main circuit at the moment is equal to the pressure change curve of the branch circuit 2, and Q=q at the moment; when the main line pressure drops to Pn again, opening the branch 3 to raise the output main line pressure, wherein the output main line pressure change curve at this time is equal to the mixed pressure change curve of the branch 2 and the branch 3, and q=2q; in this operating mode, there are at most N-1 branches operating simultaneously and there is a period of time in which only one branch is operating.
Example 6:
The present embodiment provides a supercritical fluid output method for a cryoablation system, the output method being performed using the output apparatus of embodiment 2, comprising the steps of:
(1) The liquid nitrogen is conveyed to a generator 4 by a micro pump to be heated and vaporized, the liquid nitrogen is normal pressure liquid nitrogen and is stored in a liquid nitrogen storage container 1, the heating mode in the generator 4 is resistance wire heating, after expansion and pressurization, the pressure in the generator 4 reaches 3.5MPa, and the temperature reaches-140 ℃ to form liquid nitrogen supercritical fluid;
(2) Conveying the liquid nitrogen supercritical fluid obtained in the step (1) to a heat exchanger 7, exchanging heat with liquid nitrogen in a liquid nitrogen storage container 1 to obtain cooled supercritical fluid, wherein the temperature of the supercritical fluid is minus 185 ℃, the pressure is 3.4MPa, and introducing the supercritical fluid into a supercritical fluid output trunk;
(3) Controlling the alternate opening and closing of the three supercritical fluid output branches to regulate the flow and pressure of the supercritical fluid output trunk;
in this embodiment, the working mode is also a working mode in which multiple branches are alternately opened, n=3, m is alternately changed between 2 and 3, and the change curves of the supercritical fluid output branch pressure, the output main pressure and the main flow are shown in fig. 7;
as can be seen from fig. 7, which is also a cycle of 3 branches, similar to the control process in fig. 6, the difference is that there are periods in which 3 branches are simultaneously operated, except for the period in which only branch 1 is initially turned on, followed by a process in which 2 and 3 branches alternate, and the maximum Q reaches 3Q; it can be seen that in this mode of operation, there are at most N branches operating simultaneously.
It can be seen from the above embodiments that, in the output device of the present invention, by designing a plurality of parallel branches in the storage container, and arranging a generator, a heat exchanger, and other devices on the branches, after forming the supercritical fluid from the liquid nitrogen, the temperature of the fluid is adjusted, so as to ensure the cold energy that the liquid nitrogen can provide and avoid gasification, and realize the controllable adjustment and output of the pressure and flow of the supercritical fluid; when the output device is used for cryoablation, different working modes can be adopted to meet the requirements under different application scenes, and the output device is high in safety and good in treatment effect.
The present invention is described in detail by the above embodiments, but the present invention is not limited to the above detailed devices and methods, i.e., it does not mean that the present invention must be implemented by the above detailed devices and methods. It should be apparent to those skilled in the art that any modifications of the present invention, equivalent substitutions for the apparatus of the present invention, addition of auxiliary apparatus, selection of specific modes, etc., are within the scope of the present invention and the scope of the disclosure.
The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the specific details of the above embodiments, and various simple modifications can be made to the technical solution of the present invention within the scope of the technical concept of the present invention, and all the simple modifications belong to the protection scope of the present invention.
In addition, the specific features described in the above embodiments may be combined in any suitable manner, and in order to avoid unnecessary repetition, various possible combinations are not described further.
Moreover, any combination of the various embodiments of the invention can be made without departing from the spirit of the invention, which should also be considered as disclosed herein.
Claims (10)
1. The supercritical fluid output device for the cryoablation system is characterized by comprising a liquid nitrogen storage container and at least two supercritical fluid output branches arranged in parallel in the liquid nitrogen storage container, wherein the supercritical fluid output branches arranged in parallel are converged outside the liquid nitrogen storage container to form a supercritical fluid output trunk; each output branch comprises a conveying device, a generator and a heat exchanger which are sequentially connected, and a heating device is arranged in the generator.
2. The supercritical fluid delivery apparatus according to claim 1, wherein a first one-way valve is further provided between the delivery device and the generator.
3. The supercritical fluid output apparatus according to claim 1 or 2, wherein a vacuum heat insulation layer is provided in a wall surface of the generator;
the heating device comprises a resistance wire or an electromagnetic induction heater;
and a temperature sensor is also arranged in the generator.
4. A supercritical fluid delivery apparatus according to any one of claims 1 to 3, wherein the heat exchanger is in a coiled or finned tube configuration;
a second one-way valve and a three-way electromagnetic valve are sequentially arranged on a pipeline behind the heat exchanger, and the three-way electromagnetic valve is positioned outside the liquid nitrogen storage container;
And a pressure sensor is arranged on the supercritical fluid output dry path.
5. A method of outputting a supercritical fluid using the supercritical fluid output apparatus according to any one of claims 1 to 4, comprising the steps of:
(1) Delivering liquid nitrogen to a generator for heating and vaporization, and forming liquid nitrogen supercritical fluid after expansion and pressurization;
(2) Conveying the liquid nitrogen supercritical fluid obtained in the step (1) to a heat exchanger, exchanging heat with liquid nitrogen in a liquid nitrogen storage container to obtain cooled supercritical fluid, and introducing the cooled supercritical fluid into a supercritical fluid output trunk;
(3) The opening and closing of different supercritical fluid output branches are controlled to regulate the flow and pressure of the supercritical fluid output trunk.
6. The method of claim 5, wherein the liquid nitrogen in step (1) is atmospheric liquid nitrogen, and is stored in a liquid nitrogen storage container;
The liquid nitrogen in the step (1) is conveyed into a generator by a micro pump;
The conveying pressure of the micro pump is 0.1-1 MPa;
the heating mode in the generator in the step (1) is resistance wire heating or electromagnetic induction heating;
After the liquid nitrogen in the step (1) is heated and vaporized, the pressure in the generator reaches 3.4-4.0 MPa, and the temperature reaches more than 147 ℃.
7. The method according to claim 5 or 6, wherein the supercritical fluid of liquid nitrogen in step (2) is cooled to-196 to-170 ℃ after heat exchange with liquid nitrogen;
The pressure of the liquid nitrogen supercritical fluid after heat exchange in the step (2) is 3.3-3.95 MPa;
and (2) controlling the introduction of fluid into the supercritical fluid output trunk by arranging a three-way electromagnetic valve on a pipeline from the heat exchanger to the supercritical fluid output trunk.
8. The method of any one of claims 5-7, wherein there are at least two of said supercritical fluid output branches of step (3), said output branches being simultaneously open or a portion of the branches being alternately open;
The working mode that the supercritical fluid output branch is simultaneously opened is mainly used for superficial ablation, and treatment is completed after one-time operation.
9. The method of claim 8, wherein the plurality of supercritical fluid output branches are alternately opened in a mode suitable for a situation that treatment cannot be completed by one-time operation, and the flow rate of the control fluid is kept constant or is alternately changed;
When two supercritical fluid output branches are arranged, one branch is opened, the other branch is closed, the output flow is constant, and the pressure fluctuates between the pressure of the output branch and the monitoring pressure of the output trunk.
10. The method of claim 9, wherein when three supercritical fluid output branches are provided, one of the operation modes comprises: two branches are simultaneously opened, when the output trunk circuit is reduced to the monitoring pressure, one branch is closed, the other branch is opened, and the circulation is carried out to maintain the output flow constant;
Another mode of operation includes: one branch is opened, when the output trunk is reduced to the monitoring pressure, a second branch is opened, at the moment, the output flow is doubled, when the output trunk is reduced to the monitoring pressure again, the first branch is closed, at the moment, the output flow is reduced to the initial flow, when the output trunk is reduced to the monitoring pressure again, a third branch is opened, at the moment, the output flow is doubled, and the output flow is alternately changed in a sub-circulation mode.
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