Anesthesia xenon recovery system using CHA molecular sieve membrane

Abstract

The utility model provides an anesthetic xenon recovery system utilizing a CHA molecular sieve membrane, which realizes on-line purification and reuse of xenon in an anesthetic operation process. Compared with a traditional polymer membrane material, the adopted high-silicon CHA zeolite molecular sieve membrane is remarkably improved in the aspects of gas permeability and separation selectivity, so that the membrane area can be effectively reduced, and the miniaturization of a membrane assembly is realized. The problem that xenon is wasted in the anesthesia operation process is solved through the method.

Description

Technical Field

[0001] The utility model relates to a system for purifying and recovering xenon in anesthesia exhaled gas. Specifically, a zeolite molecular sieve membrane is used to purify and recover anesthesia xenon online, belonging to the technical field of gas separation. Background Art

[0002] Xenon is a very important rare gas, which has important applications in electric light sources, aerospace ion thrusters, high-precision semiconductor manufacturing, medical magnetic resonance imaging, etc. It is known as the "golden gas". Xenon is used as an inhaled non-halogenated anesthetic drug, which has outstanding advantages such as low toxicity and side effects, organ and nerve protection, rapid induction, and rapid awakening. It is an emerging application field and is in a rapid development stage.

[0003] According to a report by Swansea University in the UK, the average loss of xenon during clinical anesthesia is 15L / operation. Air is the only source of commercial xenon, and given that its content is only 0.086ppm, the global xenon production is also very limited. At present, my country's annual xenon production is about 10,000Nm 3 , all used as anesthetics can meet the needs of 650,000 surgeries, accounting for only 7.8‰ of the total number of surgeries in the country. At the same time, the cost of producing xenon through deep cold distillation is extremely expensive, and its market price is as high as 200,000 to 550,000 yuan / Nm 3 , resulting in clinical application costs that are 30 to 100 times that of traditional inhaled anesthetics such as sevoflurane. Compared with the potential demand for anesthesia, the limited supply and high price of xenon are the key technical bottlenecks restricting its promotion nationwide.

[0004] At present, the main technologies used for xenon purification and recovery include adsorption based on porous materials, deep cold air separation distillation, etc. Philip A. Barrett of Praxair Inc. in the United States disclosed an adsorption process for xenon recovery at low temperature using Ag-X zeolite molecular sieves (US2016 / 15244359), and the xenon concentration increased by more than 50 times after desorption. Quzhou Hangyang Special Gas Co., Ltd. also disclosed a krypton and xenon deep cold distillation production process based on molecular sieve adsorption purification raw materials and pre-cooling heat exchangers (CN108408701B). Although the development of new adsorption materials and the optimization of distillation processes have improved the efficiency of xenon recovery, there are still problems such as high energy consumption, complex processes, and discontinuous processes, which cannot meet the online purification and recovery of xenon during clinical surgery.

[0005] Membrane separation technology can meet the technical requirements of real-time and continuous purification and recovery of xenon in anesthesia exhaled gas. At the same time, driven by the pressure difference on both sides of the membrane, the difference in gas molecular kinetic diameter and permeation rate is used to separate the mixed components. There is no phase change involved in the process, which can significantly reduce the energy consumption of xenon purification and recovery. A. Mendes et al. of Universidade do Porto, Portugal proposed a method for recovering anesthesia xenon using carbon molecular sieve membrane (J. Membr. Sci, 301, 29-38), with nitrogen and carbon dioxide gas fluxes of 3 GPU and 110 GPU respectively; subsequently, Air Liquide of France disclosed a method for recovering anesthesia xenon using polymer membrane (US2009 / 0126733), which increased the nitrogen and carbon dioxide gas fluxes to 40 GPU and 250 GPU respectively. However, the gas permeability of carbon molecular sieve membranes and polymer membranes is low, and it is still difficult to meet the technical requirements of miniaturization and portability of respiratory anesthesia machines. Summary of the invention

[0006] The utility model uses high-silicon CHA zeolite molecular sieve membrane for online purification and recovery of xenon in respiratory anesthesia machines. In an equimolar two-component mixed gas system of carbon dioxide and xenon, the carbon dioxide gas permeability is 3×10 -7 mol·m -2 ·s -1 ·Pa -1 (~880 GPU), xenon permeability is 3×10 -10 mol·m -2 ·s -1 ·Pa -1 (<1GPU), the separation selectivity of carbon dioxide to xenon exceeds 1000. The gas permeability of carbon dioxide and the separation selectivity of carbon dioxide to xenon are one order of magnitude higher than those of traditional polymer membrane materials. The excellent membrane separation performance is attributed to the difference in the diffusion rate of gas molecules in the pores of the zeolite molecular sieve and the strong size screening effect of the high-silicon CHA zeolite molecular sieve.

[0007] In clinical surgery with xenon anesthesia, the gas volume concentration of the anesthetic waste gas exhaled by the patient is roughly: 5% carbon dioxide, 30% air and 65% xenon. Under this concentration condition, 30 pieces of 40cm long high-silicon CHA zeolite molecular sieves (45cm 2 / branch) through cluster packaging composed of membrane components (membrane area 0.13m 2 ) can process 1L·min -1 Exhaled waste gas during anesthesia, the recovery flow rate is 0.9L·min -1; The xenon concentration is 70%, the recovery rate is 97%; the carbon dioxide concentration is 1%, the removal rate is 82%; the air concentration is 29%, and the air permeability is 13%. At this time, the xenon concentration meets the MAC (0.7) value required for anesthesia.

[0008] The utility model provides an anesthetic xenon gas recovery system using a CHA molecular sieve membrane, the system comprising a dryer, a membrane assembly and a respiratory anesthesia machine, the dryer is used to dry the gas containing xenon, the respiratory anesthesia machine is used to provide purified anesthetic gas, the respiratory anesthesia machine is connected to an O2 gas storage source and a Xe gas storage source, the membrane assembly is connected between the dryer and the respiratory anesthesia machine through a pipeline, the membrane assembly is provided with a CHA molecular sieve membrane, and the high-silicon CHA zeolite molecular sieve membrane area used is 0.1-1.5 m 2 The size of the membrane component after packaging is Φ3×40~Φ12×40.

[0009] Preferably, a gas concentration detector is provided on the recovery gas pipeline between the membrane assembly and the respiratory anesthesia machine and on the pipeline used by the respiratory anesthesia machine to provide purified anesthetic gas. Flow controllers are respectively provided on the pipelines connecting the respiratory anesthesia machine and the O2 gas storage source and the Xe gas storage source. The gas concentration detector adjusts the flow through digital signal feedback.

[0010] Preferably, a gas concentration detector is provided on the exhaled air intake pipeline connected to the dryer.

[0011] Preferably, the permeate side of the membrane assembly is connected to a negative pressure system.

[0012] Preferably, an exhaust valve is provided on the recovery air pipeline between the membrane assembly and the respiratory anesthesia machine.

[0013] Beneficial Effects

[0014] The utility model provides an anesthesia xenon gas recovery system using CHA molecular sieve membrane, which realizes online purification and recycling of xenon gas during anesthesia surgery. The high-silicon CHA zeolite molecular sieve membrane used has significantly improved gas permeability and separation selectivity compared to traditional polymer membrane materials, so it can effectively reduce the membrane area, thereby realizing the miniaturization of the membrane component. This method solves the problem of xenon gas waste during anesthesia surgery.

[0015] The pore size of the high silicon CHA zeolite molecular sieve used in the utility model is Right between carbon dioxide and xenon As an inorganic porous material with a high silicon-aluminum ratio (Si / Al>5), its excellent hydrophobicity and stable skeleton structure ensure its high xenon online purification capability even in the presence of water vapor. In addition, temperature tolerance (-50℃~230℃) and oxidation resistance (ozone atmosphere) are also key factors for the long-term stable operation of high-silicon CHA molecular sieve membranes during surgical disinfection. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the online purification and recycling of respiratory anesthesia xenon gas using membrane separation method.

[0017] Figure 2 It is a schematic diagram of high-silicon CHA zeolite molecular sieve membrane components with different filling amounts used in the utility model.

[0018] Figure 3 The high-silicon CHA zeolite molecular sieve membrane module was used in anesthesia exhaled waste gas at different feed flow rates (750 mL min -1 ~1500mL·min -1 ) Separation performance diagram. Among them, (a) Xenon loss rate and Xenon concentration on the recovery side change with pressure; (b) Carbon dioxide removal rate and Carbon dioxide concentration on the recovery side change with pressure; (c) Air removal rate and Air concentration on the recovery side change with pressure; (d) Stage-cut change with pressure. DETAILED DESCRIPTION

[0019] The high-silicon CHA zeolite molecular sieve membrane used in the following examples can be prepared by referring to the prior art, such as CN 116002709B "A method for preparing SSZ-13 molecular sieve membrane".

[0020] Example 1

[0021] like Figure 1 As shown, this embodiment provides an anesthetic xenon gas recovery system using a CHA molecular sieve membrane, the system comprising a dryer, a membrane assembly and a respiratory anesthesia machine, the dryer is used to dry the gas containing xenon, the respiratory anesthesia machine is used to provide purified anesthetic gas, the respiratory anesthesia machine is connected to an O2 gas storage source and a Xe gas storage source, the membrane assembly is connected between the dryer and the respiratory anesthesia machine through a pipeline, the membrane assembly is provided with a CHA molecular sieve membrane, and the high-silicon CHA zeolite molecular sieve membrane used has an area of ​​0.1 to 1.5 m 2 ( Figure 2Three schematic diagrams of high-silicon CHA zeolite molecular sieve membrane assemblies with different filling amounts are listed, and the size of the encapsulated membrane assembly is Φ3×40~Φ12×40. A gas concentration detector is provided on the recovery air pipeline between the membrane assembly and the respiratory anesthesia machine, and on the pipeline used by the respiratory anesthesia machine to provide purified anesthetic gas. Flow controllers are respectively provided on the pipelines connecting the respiratory anesthesia machine and the O2 gas storage source and the Xe gas storage source. The gas concentration detector adjusts the flow rate through digital signal feedback. A gas concentration detector is provided on the exhaled air inlet pipeline connected to the dryer. The permeation side of the membrane assembly is connected to the negative pressure system. An exhaust valve is provided on the recovery air pipeline between the membrane assembly and the respiratory anesthesia machine.

[0022] The workflow of high-silicon CHA zeolite molecular sieve membrane in online purification and recycling of xenon gas for respiratory anesthesia:

[0023] (1) The membrane module is connected to the respiratory anesthesia machine through a pipeline; (2) The gas inlet of the membrane module, the gas outlet on the recovery side and the gas outlet of the respiratory anesthesia machine are respectively equipped with online concentration monitors (real-time monitoring of carbon dioxide, oxygen and xenon concentration changes); (3) The gas outlet on the permeate side of the membrane module is connected to the negative pressure system of the operating room; (4) The anesthesia ventilator is equipped with medical xenon and medical oxygen cylinders; (5) The gas outlet on the recovery side is equipped with an exhaust valve (safety valve). When the pressure in the pipeline is too high, the exhaust valve automatically opens to ensure normal breathing of the patient; (6) After the operation, the xenon outlet valve is closed, the compressor is started, and all the remaining xenon in the respiratory anesthesia pipeline system is recovered and filled into the recovery gas cylinder. Before the subsequent operation begins, the pipeline is pre-filled with the xenon-oxygen mixture in the recovery gas cylinder.

[0024] Before the start of the anesthesia surgery, the entire respiratory system is filled with a mixture of xenon and oxygen (xenon concentration is 70%, oxygen concentration is 30%). During the operation, the patient's exhaled anesthetic waste gas is separated from carbon dioxide and xenon and the xenon gas is recovered in the membrane assembly; at the same time, the patient will continue to consume oxygen and xenon during the operation, and metabolize to produce carbon dioxide. Therefore, according to the gas concentration and flow obtained at the gas outlet on the recovery side and the gas outlet of the respiratory anesthesia machine, the flow valve is adjusted to timely add fresh xenon and oxygen to the closed-loop circulation system to complete the purification and reuse of the exhaled anesthetic waste gas. When performing the separation of the gas containing xenon, the flow rate of the feed gas is 100-8000mL·min -1 , the feed gas pressure is 0.1MPa~1.2MPa, the permeate side pressure is 100Pa~0.1MPa, and the temperature is 10~30℃. The xenon recovery rate is above 90%.

[0025] Example 2

[0026] Separation performance of high-silica CHA zeolite molecular sieve membrane modules in anesthesia exhaled waste gas

[0027] Using three different flow rates (750 mL min -1 、1000mL·min -1 、1500mL·min -1 ) anesthesia exhaled waste gas was used to test the xenon online purification and recovery performance of the high-silicon CHA zeolite molecular sieve membrane module. The results are as follows Figure 3 shown.

[0028] As the feed pressure (gauge pressure) increases from 0MPa to 1.2MPa, the xenon concentration on the recovery side can always be maintained at around 70%, meeting the xenon anesthesia MAC (0.7) value. The xenon loss rate gradually increases with pressure, because the contribution rate of xenon through the molecular sieve membrane through Knudsen diffusion increases, but the loss rate is always maintained within 15%, and as the feed flow rate increases to 1500mL·min -1 , the loss rate of xenon gas is further reduced, and even when the feed pressure is 1.2 MPa, the loss rate of xenon gas is still less than 5%.

[0029] At the same feed pressure, the carbon dioxide removal rate gradually decreases with the increase of feed flow rate, resulting in an increase in the carbon dioxide concentration on the recovery side. However, with the increase of pressure, the carbon dioxide concentration does not show a monotonically decreasing trend. This is because the carbon dioxide concentration on the feed side decreases, resulting in a decrease in the transmembrane pressure difference and a weakened separation effect.

[0030] Stage-cut, also known as cutting rate (θ), is defined as the ratio of the permeate side to the feed flow rate. As the pressure increases, the stage-cut increases linearly.

[0031] The above is only a preferred specific implementation method of the utility model, but the protection scope of the utility model is not limited to it. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and utility model concept of the utility model within the technical scope disclosed by the utility model, which should be covered by the protection scope of the utility model.

Claims

1. An anesthetic xenon gas recovery system using CHA molecular sieve membrane, characterized in that The system includes a dryer, a membrane assembly and a respiratory anesthesia machine. The dryer is used to dry gas containing xenon, the respiratory anesthesia machine is used to provide purified anesthetic gas, the respiratory anesthesia machine is connected to an O2 gas storage source and a Xe gas storage source, the membrane assembly is connected between the dryer and the respiratory anesthesia machine through a pipeline, and a CHA molecular sieve membrane is arranged in the membrane assembly.

2. The anesthesia xenon gas recovery system using CHA molecular sieve membrane according to claim 1, characterized in that: The membrane area of ​​CHA molecular sieve membrane is 0.1~1.5m 2 The size of the membrane component after packaging is Φ3×40~Φ12×40.

3. The anesthesia xenon gas recovery system using CHA molecular sieve membrane according to claim 1, characterized in that Gas concentration detectors are provided on the recovery gas pipeline between the membrane assembly and the respiratory anesthesia machine and on the pipeline of the respiratory anesthesia machine for providing purified anesthetic gas.

4. The anesthesia xenon gas recovery system using CHA molecular sieve membrane according to claim 1, characterized in that Flow controllers are respectively provided on the pipelines connecting the respiratory anesthesia machine and the O2 gas storage source and the Xe gas storage source.

5. The anesthesia xenon gas recovery system using CHA molecular sieve membrane according to claim 1, characterized in that A gas concentration detector is provided on the exhaled air intake pipeline connected to the dryer.

6. The anesthesia xenon gas recovery system using CHA molecular sieve membrane according to claim 1, characterized in that The permeate side of the membrane assembly is connected to a negative pressure system.

7. The anesthesia xenon gas recovery system using CHA molecular sieve membrane according to claim 1, characterized in that An exhaust valve is arranged on the recovery air pipeline between the membrane assembly and the respiratory anesthesia machine.

Images