Mixed gas and gas distribution method for shield operation

Abstract

The present invention provides a mixed gas for shield operation, comprising oxygen, helium and nitrogen, characterized in that the partial pressure P of oxygen in the mixed gas is O The partial pressure of nitrogen is 1.4-2.0ATA, P N ≤4ATA, the rest is helium, wherein the partial pressures of the nitrogen and helium should also satisfy #imgabs0#, where P He The partial pressure of helium is 6 bar (7 ATA). This invention effectively solves the problem of being unable to use air pressure for cabin opening operations at pressures above 6 bar (7 ATA). By setting appropriate oxygen and nitrogen partial pressures, as well as the relationship between nitrogen and helium partial pressures, it effectively ensures the physical comfort and life safety of operators. It eliminates the need for special equipment, such as that required when using helium-oxygen saturation pressure, making operations more convenient and efficient.

Description

Technical Field

[0001] The invention belongs to the field of gas distribution, and in particular relates to a mixed gas for shield operation and a gas distribution method. Background Art

[0002] Most traditional shield machine tool replacement methods use air pressure to replace tools, that is, compressed air is used to enter the cabin for operation. The disadvantages of this method include: exceeding the limit of 6.0 bar of compressed air cabin opening technology; each shift of compressed air operation must perform pressurization and decompression to normal pressure procedures, the effective working time of each shift is only 20 to 25 minutes, and the total decompression time is more than 180 minutes, which is inefficient and greatly affects the progress of the project; the decompression procedure is performed multiple times a day, the incidence of decompression sickness is high, and it is harmful to the health of the workers; the workers breathe compressed air, the density of the breathing gas increases, the breathing resistance increases, and the work capacity decreases; the anesthetic effect of nitrogen in the compressed air leads to a serious reduction in the risk awareness and judgment ability of the workers, which is prone to personal injury accidents.

[0003] The Chinese utility model patent with patent announcement number CN203961982U discloses a method for saturated cabin opening operation under shield compressed air conditions, comprising the following steps: at least one living cabin for daily life of the workers and at least one movable shuttle cabin are provided on the ground, and the saturated cabin opening operation method under shield compressed air conditions comprises the following steps: the workers first enter the living cabin and pressurize the living cabin so that the pressure inside the living cabin is the same as the shield machine incision pressure; when it is necessary to enter the cabin for operation, the shuttle cabin with the same pressure as the pressure inside the living cabin is connected to the living cabin, and the workers enter the shuttle cabin from the living cabin; the shuttle cabin is connected to the living cabin. The living cabin is detached from the living cabin, and a transport vehicle transports the workers into the tunnel. The shuttle cabin is then connected to the manlock cabin on the shield machine, where the pressure inside the shuttle cabin is the same as the pressure inside the cabin. Workers enter the manlock cabin from the shuttle cabin and then proceed to the mud and water cabin, which has the same pressure as the manlock cabin, to begin tool maintenance work. After each shift of tool maintenance work is completed, the workers return to the manlock cabin and then enter the shuttle cabin. The shuttle cabin is detached from the manlock cabin and transported to the surface to connect to the living cabin, where they return to rest. This process is repeated each time they enter the cabin until tool maintenance work is complete. The living cabin is depressurized every 15 to 20 days. The living cabin is pressurized with a gas mixture consisting of helium, nitrogen, and oxygen, with a volume ratio of 75% ± 5% helium, 20% ± 5% nitrogen, and 5% ± 2% oxygen. However, this helium-oxygen saturation pressurization requires the use of special wearable equipment, which significantly reduces work efficiency. Summary of the Invention

[0004] In order to solve the problems existing in the prior art, the present invention provides a mixed gas for shield operation, which aims to solve the problem that air pressurized cabin operation cannot be used when the working pressure is above 6 bar, and the use of helium-oxygen saturated pressurized operation requires wearing special equipment, which affects the working efficiency.

[0005] One aspect of the present invention provides a mixed gas for shield operation, comprising oxygen, helium and nitrogen, wherein the partial pressure of oxygen in the mixed gas is P O The partial pressure of nitrogen is 1.4~2.0ATA, P N ≤4ATA, the rest is helium, wherein the partial pressures of the nitrogen and helium should also meet , where P He is the partial pressure of helium.

[0006] As a preferred solution of the mixed gas for shield operation of the present invention, the total pressure P of the mixed gas is ≤9.5ATA.

[0007] As a preferred embodiment of the mixed gas for shield operation of the present invention, the total pressure P of the mixed gas is 5-8 ATA.

[0008] As a preferred embodiment of the present invention, the total pressure P of the mixed gas for shield operation is 5ATA, the partial pressure P of the oxygen is O is 1.6ATA, the partial pressure of nitrogen P N is 1.5ATA, the partial pressure of helium P He It is 1.9ATA.

[0009] As a preferred embodiment of a mixed gas for shield operation of the present invention, the total pressure P of the mixed gas is 6ATA, the partial pressure P of the oxygen is O is 1.7ATA, the partial pressure of nitrogen P N is 1.9ATA, the partial pressure of helium P He It is 2.4ATA.

[0010] As a preferred embodiment of the present invention, the total pressure P of the mixed gas for shield operation is 7ATA, the partial pressure P of the oxygen is 7ATA, and the total pressure P of the mixed gas is 7ATA. O is 1.8ATA, the partial pressure of nitrogen P N is 2.3ATA, the partial pressure of helium P He It is 2.9ATA.

[0011] Another aspect of the present invention provides a method for distributing mixed gas for shield operation, comprising the following steps:

[0012] 1) Obtain the pressure of the working environment to obtain the total pressure P of the mixed gas and set the partial pressure P of oxygen O1.4~2.0ATA;

[0013] 2) According to the total pressure P of the mixed gas and the oxygen partial pressure P O Calculate the sum of the pressures of nitrogen and helium in the mixed gas P N +P He =PP O , then combine the formula and P N ≤4ATA Determine the partial pressures of nitrogen and helium in a gas mixture.

[0014] As a preferred embodiment of the gas distribution method for a mixed gas for shield tunneling operation of the present invention, the method further includes the step of selecting a specific partial pressure value within the partial pressure range of nitrogen and helium in the mixed gas.

[0015] The present invention's solution reveals that when the oxygen partial pressure is too low, workers may experience hypoxia. Symptoms include: mild hypoxia: dizziness, fatigue, and decreased concentration; moderate hypoxia: difficulty breathing, rapid heartbeat, and confusion; severe hypoxia: coma, organ failure, and death. Excessive oxygen partial pressure can lead to oxygen toxicity, and acute oxygen toxicity exceeding 2.0 ATA can cause central nervous system symptoms: convulsions, loss of consciousness, visual impairment, tinnitus, and nausea. Based on this, the present invention effectively avoids these problems by controlling the oxygen partial pressure of the mixed gas within the range of 1.4 to 2.0 ATA.

[0016] The present invention's solution reveals that excessively high nitrogen partial pressure can lead to nitrogen narcosis, typically occurring when the nitrogen partial pressure exceeds 3.2 ATA. The risk increases significantly when the nitrogen partial pressure exceeds 4 ATA, with the risk increasing with greater depth, the likelihood of occurrence, and the symptoms becoming more pronounced. The higher the nitrogen partial pressure, the greater the risk of decompression sickness. Therefore, the present invention controls the nitrogen partial pressure of the mixed gas within a range of ≤4 ATA, effectively preventing this problem.

[0017] Based on the solution of the present invention, it is found that the partial pressure relationship of nitrogen and helium in the mixed gas has a significant impact on the health of the operator during operation and decompression. When the nitrogen partial pressure and helium partial pressure in the mixed gas meet It can effectively prevent workers from feeling uncomfortable during operation and decompression.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The present invention can effectively solve the problem that it is impossible to use air pressure to perform cabin opening operations under pressure conditions above 6 bar (i.e. 7 ATA);

[0020] 2. The present invention can effectively ensure the physical comfort and life safety of workers by setting appropriate oxygen partial pressure, nitrogen partial pressure, and the relationship between nitrogen and helium partial pressures;

[0021] 3. The present invention does not require special equipment such as that required when helium-oxygen saturation pressure is used, and the operation is convenient for operators and has high operating efficiency.

[0022] It should be noted that, in the present invention, shield tunneling operations encompass not only the work performed by personnel within the shield tunneling environment, but also the decompression process. All pressures or partial pressures in this invention referred to in units of ATA are absolute pressures, and the conversion relationship between ATA and gauge pressure (bar) is: absolute pressure (ATA) = gauge pressure (bar) + 1. DETAILED DESCRIPTION

[0023] The following will be a clear and complete description of the technical solutions in the embodiments. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0024] Example 1

[0025] A mixed gas for shield operation, comprising oxygen, helium and nitrogen, wherein the partial pressure of oxygen in the mixed gas is P O is 1.6ATA, the partial pressure of nitrogen P N is 1.9ATA, helium partial pressure P He It is 1.5ATA.

[0026] The gas distribution method of the mixed gas comprises:

[0027] 1) The ambient pressure during the operation is 4.0 bar (i.e. the total pressure of the mixed gas is 5 ATA), the operation time is 105 min, and according to the partial pressure of oxygen in the mixed gas P O Set the oxygen partial pressure P to a standard of 1.4~2.0ATA O 1.6ATA;

[0028] 2) Calculate the sum of the partial pressures of nitrogen and helium based on the total pressure of the mixed gas and the partial pressure of oxygen obtained in step 1) N +P He =3.4ATA, then combine the formula and P N ≤4ATA Determine the partial pressure P of helium in the mixed gas He <1.58ATA, nitrogen partial pressure 1.82ATA<P N≤3.4ATA, all partial pressure values within this range can achieve the technical effects of the present invention;

[0029] 3) Based on the partial pressure ranges of helium and nitrogen determined in step 2), further select the specific partial pressure value P He =1.5ATA、P N =1.9ATA for gas distribution, and the specific gas distribution plan under the operating conditions is obtained.

[0030] It has been verified through actual operation that the operators did not experience any discomfort within the environmental pressure and operation time set in this embodiment.

[0031] After the operation was completed, decompression was performed based on a conventional decompression scheme in the art. The decompression scheme determined based on the working conditions of this embodiment was a decompression depth of 24m and a decompression time of 87min (excluding 1min of transition time between each stop). Within this decompression scheme, the operator did not experience any discomfort.

[0032] Example 2

[0033] A mixed gas for shield operation, comprising oxygen, helium and nitrogen, wherein the partial pressure of oxygen in the mixed gas is P O is 1.7ATA, the partial pressure of nitrogen P N is 2.4ATA, helium partial pressure P He It is 1.9ATA.

[0034] The gas distribution method of the mixed gas comprises:

[0035] 1) The ambient pressure during the operation is 5.0 bar (i.e. the total pressure of the mixed gas is 6 ATA), the operation time is 60 minutes, and according to the partial pressure of oxygen in the mixed gas P O Set the oxygen partial pressure P to a standard of 1.4~2.0ATA O 1.7ATA;

[0036] 2) Calculate the sum of the partial pressures of nitrogen and helium based on the total pressure of the mixed gas and the partial pressure of oxygen obtained in step 1) N +P He =4.3ATA, then combine the formula and P N ≤4ATA Determine the partial pressure of helium in the mixed gas 0.3ATA≤P He <2.01ATA, nitrogen partial pressure 2.29ATA<P N ≤4ATA, all partial pressure values within this range can achieve the technical effects of the present invention;

[0037] 3) Based on the partial pressure ranges of helium and nitrogen determined in step 2), further select the specific partial pressure value PHe =1.9ATA、P N =2.4ATA for gas distribution, and the specific gas distribution plan under the operating conditions is obtained.

[0038] It has been verified through actual operation that the operators did not experience any discomfort within the environmental pressure and operation time set in this embodiment.

[0039] After the operation was completed, decompression was performed based on a conventional decompression scheme in the art. The decompression scheme determined based on the working conditions of this embodiment was a decompression depth of 30m and a decompression time of 83min (excluding 1min of transition time between each stop). Within this decompression scheme, the operator did not experience any discomfort.

[0040] Example 3

[0041] A mixed gas for shield operation, comprising oxygen, helium and nitrogen, wherein the partial pressure of oxygen in the mixed gas is P O is 1.8ATA, the partial pressure of nitrogen P N is 2.9ATA, helium partial pressure P He It is 2.3ATA.

[0042] The gas distribution method of the mixed gas comprises:

[0043] 1) The ambient pressure during the operation is 6.0 bar (i.e. the total pressure of the mixed gas is 7 ATA), the operation time is 60 minutes, and according to the partial pressure of oxygen in the mixed gas P O Set the oxygen partial pressure P to a standard of 1.4~2.0ATA O 1.8ATA;

[0044] 2) Calculate the sum of the partial pressures of nitrogen and helium based on the total pressure of the mixed gas and the partial pressure of oxygen obtained in step 1) N +P He =5.2ATA, then combine the formula and P N ≤4ATA Determine the partial pressure of helium in the mixed gas 1.2ATA≤P He <2.43ATA, nitrogen partial pressure 2.77ATA<P N ≤4ATA, all partial pressure values within this range can achieve the technical effects of the present invention;

[0045] 3) Based on the partial pressure ranges of helium and nitrogen determined in step 2), further select the specific partial pressure value P He =2.3ATA、P N =2.9ATA for gas distribution, and the specific gas distribution plan under the operating conditions is obtained.

[0046] It has been verified through actual operation that the operators did not experience any discomfort within the environmental pressure and operation time set in this embodiment.

[0047] After the operation was completed, decompression was performed based on a conventional decompression scheme in the art. The decompression scheme determined based on the working conditions of this embodiment was a decompression depth of 36 m and a decompression time of 109 min (excluding 1 min of transition time between each stop). Within this decompression scheme, the operator did not experience any discomfort.

[0048] It should be noted that, according to the above-described embodiments of the present invention, those skilled in the art are fully capable of implementing the full scope of the independent claims and dependent claims of the present invention, and the implementation processes and methods are the same as those of the above-described embodiments; and the parts not described in detail in the present invention belong to the common technology in the art. However, the scope of protection of the present invention is not limited to these, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be covered by the scope of protection of the present invention.

Claims

1. A mixed gas for shield operation, comprising oxygen, helium and nitrogen, characterized in that: The partial pressure of oxygen in the mixed gas P O The partial pressure of nitrogen is 1.4~2.0ATA, P N ≤4ATA, the rest is helium, wherein the partial pressures of the nitrogen and helium should also meet , where P He is the partial pressure of helium.

2. The mixed gas according to claim 1, wherein The total pressure P of the mixed gas is ≤9.5ATA.

3. The mixed gas according to claim 1, wherein The total pressure P of the mixed gas is 5-8 ATA.

4. The mixed gas according to claim 1, wherein The total pressure of the mixed gas P is 5ATA, the partial pressure of the oxygen P O is 1.6ATA, the partial pressure of nitrogen P N is 1.9ATA, the partial pressure of helium P He It is 1.5ATA.

5. The mixed gas according to claim 1, wherein: The total pressure of the mixed gas P is 6ATA, the partial pressure of the oxygen P O is 1.7ATA, the partial pressure of nitrogen P N is 2.4ATA, the partial pressure of helium P He It is 1.9ATA.

6. The mixed gas according to claim 1, wherein The total pressure of the mixed gas P is 7ATA, the partial pressure of the oxygen P O is 1.8ATA, the partial pressure of nitrogen P N is 2.9ATA, the partial pressure of helium P He It is 2.3ATA.

7. A method for distributing mixed gas for shield operation, characterized in that: The steps include: 1) Obtain the pressure of the working environment to obtain the total pressure P of the mixed gas and set the partial pressure P of oxygen O 1.4-2.0ATA; 2) According to the total pressure P of the mixed gas and the oxygen partial pressure P O Calculate the sum of the pressures of nitrogen and helium in the mixed gas P N +P He =PP O , then combine the formula and P N ≤4ATA Determine the partial pressures of nitrogen and helium in a gas mixture.

8. The gas distribution method according to claim 7, characterized in that: The method further includes the step of selecting a specific partial pressure value within the determined partial pressure range of nitrogen and helium in the mixed gas.

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