Mixed gas for shield operation and gas distribution method

Abstract

The invention provides a mixed gas for shield operation, which comprises oxygen, helium and nitrogen, and is characterized in that the partial pressure PO of the oxygen in the mixed gas is 1.4-2.0 ATA, the partial pressure PN of the nitrogen is less than or equal to 4ATA, the rest is helium, the partial pressure of the nitrogen and the partial pressure of the helium should meet # imgabs0 #, and in the formula, PHe is the partial pressure of the helium. According to the invention, the problem that the cabin opening operation cannot be carried out by adopting air under pressure under the pressure condition of more than 6bar (namely 7ATA) can be effectively solved; by setting proper oxygen partial pressure, nitrogen partial pressure and the partial pressure relationship between nitrogen and helium, the body comfort and life safety of operators can be effectively guaranteed; and special equipment required by helium-oxygen saturation under pressure does not need to be adopted, so that the operation of operators is convenient, and the operation efficiency is high.

Description

Technical Field

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

[0002] In the traditional replacement of shield machine cutters, most of them adopt the method of replacing cutters under air pressure, that is, the method of using compressed air to enter the cabin for operation. The disadvantages of this method include: the limit of the compressed air opening cabin technology is limited to 6.0 bar; the pressurization and decompression to normal pressure procedures must be performed for each shift of compressed air operation, and the effective working time for each shift is only 20 - 25 minutes, and the total decompression time is greater than 180 minutes, resulting in low work efficiency and greatly affecting the project progress; the decompression procedure is performed multiple times a day, with a relatively high incidence of decompression sickness, endangering the physical health of operators; operators breathe compressed air, the density of the breathing gas increases, the breathing resistance increases, and the working ability decreases; the narcotic effect of nitrogen in compressed air causes the risk awareness and judgment ability of operators to be severely reduced, and it is easy to cause personal injury accidents.

[0003] The Chinese utility model patent with the patent announcement number CN203961982U discloses a saturated open cabin operation method under shield compressed air conditions, including the following steps: at least one living cabin for the daily life of operators and at least one movable shuttle cabin are provided on the ground. The saturated open cabin operation method under shield compressed air conditions includes the following steps: operators first enter the living cabin, and pressurize the living cabin so that the pressure in the living cabin is the same as the cutterhead pressure of the shield machine; when entering the cabin for operation is required, connect the shuttle cabin with the same pressure as that in the living cabin to the living cabin, and the operators enter the shuttle cabin from the living cabin; disconnect the shuttle cabin from the living cabin, transport the shuttle cabin carrying the operators to the tunnel by a transport vehicle, and connect the shuttle cabin to the man lock cabin on the shield machine with the same pressure as that in the shuttle cabin; the operators enter the man lock cabin from the shuttle cabin and enter the slurry chamber with the same pressure as the man lock cabin through the man lock cabin to start the cutter repair work; after the cutter repair work for each shift is completed, the operators return to the man lock cabin and then enter the shuttle cabin, disconnect the shuttle cabin from the man lock cabin and transport it to the ground to connect with the living cabin, and the operators return to the living cabin to rest; then repeat the above steps each time entering the cabin for operation until all the cutter repair work is completed, and the living cabin is decompressed every 15 - 20 days during this period. A mixed gas is used to pressurize the living cabin, and the mixed gas includes helium, nitrogen and oxygen. The volume content of helium is 75% ± 5%, the volume content of nitrogen is 20% ± 5%, and the volume content of oxygen is 5% ± 2%. However, the above helium-oxygen saturation under pressure requires special wearing equipment to carry out the operation, thus greatly reducing the operation efficiency. Summary of the Invention

[0004] To solve the problems existing in the prior art, the present invention provides a mixed gas for shield operation, aiming to solve the problems that air pressure cabin opening operation cannot be carried out when the working pressure is above 6 bar and the use of helium-oxygen saturation pressure requires wearing special equipment, which affects the operation efficiency.

[0005] One aspect of the present invention provides a mixed gas for shield operation, including oxygen, helium and nitrogen. The partial pressure P of oxygen in the mixed gas O is 1.4 - 2.0 ATA, and the partial pressure P of nitrogen N ≤ 4 ATA, and the rest is helium. Among them, the partial pressures of the nitrogen and the helium should also satisfy , 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 ≤ 9.5 ATA.

[0007] As a preferred solution 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 solution of the mixed gas for shield operation of the present invention, the total pressure P of the mixed gas is 5 ATA, the partial pressure P of oxygen O is 1.6 ATA, the partial pressure P of nitrogen N is 1.5 ATA, and the partial pressure P of helium He is 1.9 ATA.

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

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

[0011] Another aspect of the present invention provides a gas mixing method for the mixed gas for shield operation, including 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 Ois 1.4 to 2.0 ATA;

[0013] 2) According to the total pressure P of the mixed gas and the partial pressure of oxygen P O The sum of the pressures of nitrogen and helium in the mixed gas, P N +P He =P - P O is calculated, and then combined with the formula and P N ≤ 4 ATA to determine the partial pressures of nitrogen and helium in the mixed gas.

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

[0015] Based on the solution of the present invention, it is found that when the partial pressure of oxygen is too low, the operator may experience hypoxia. Symptoms: mild hypoxia: dizziness, fatigue, decreased attention; moderate hypoxia: dyspnea, tachycardia, confusion; severe hypoxia: coma, organ failure, death. When the partial pressure of oxygen is too high, oxygen poisoning may be caused. When the partial pressure of oxygen exceeds 2.0 ATA, acute oxygen poisoning may be caused. Symptoms: central nervous system symptoms: convulsions, loss of consciousness, visual impairment, tinnitus, nausea. Based on this, the present invention controls the partial pressure of oxygen in the mixed gas within the range of 1.4 to 2.0 ATA, which can effectively avoid the occurrence of the above problems.

[0016] Based on the solution of the present invention, it is found that too high partial pressure of nitrogen may cause nitrogen narcosis. Usually, nitrogen narcosis may occur when the partial pressure of nitrogen > 3.2 ATA. When the partial pressure of nitrogen > 4 ATA, the risk of nitrogen narcosis will increase significantly, and the deeper the depth, the easier it is to occur, and the more obvious the symptoms are. The higher the partial pressure of nitrogen, the greater the risk of decompression sickness. Based on this, the present invention controls the partial pressure of nitrogen in the mixed gas within the range of ≤ 4 ATA, which can effectively avoid the occurrence of the above problems.

[0017] Based on the solution of the present invention, it is found that the relationship between the partial pressures of nitrogen and helium in the mixed gas has a significant impact on the body of the operator during operation and decompression. When the partial pressures of nitrogen and helium in the mixed gas satisfy the discomfort of the operator during operation and decompression can be effectively avoided.

[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 carry out the operation of opening the cabin with air under pressure under the pressure condition of more than 6 bar (i.e., 7 ATA);

[0020] 2. By setting appropriate oxygen partial pressure, nitrogen partial pressure, and the partial pressure relationship between nitrogen and helium, the present invention can effectively ensure the physical comfort and life safety of operators.

[0021] 3. The present invention does not require special equipment needed for, for example, helium-oxygen saturation under pressure. It is convenient for operators to work and has high work efficiency.

[0022] It should be noted that in the present invention, shield operation not only includes the work of operators in the shield environment but also includes the decompression procedure. Among the various pressures or partial pressures in the present invention, those with the unit of ATA are absolute pressures, and the conversion relationship between them and gauge pressure (bar) is absolute pressure (ATA) = gauge pressure (bar) + 1. Detailed Embodiment

[0023] The technical solutions in the embodiments will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0024] Embodiment 1

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

[0026] The gas distribution method of the above mixed gas includes:

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

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

[0029] 3) Further select specific partial pressure values P based on the partial pressure ranges of helium and nitrogen determined in step 2) He = 1.5ATA, P N = 1.9ATA for gas mixing, and the specific gas mixing scheme under this operating condition can be obtained.

[0030] Through actual operation verification, within the environmental pressure and operation time set in this embodiment, the operators did not experience any discomfort.

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

[0032] Example 2

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

[0034] The gas mixing method of the above-mentioned mixed gas includes:

[0035] 1) Obtain the environmental pressure during operation as 5.0 bar (i.e., the total pressure of the mixed gas is 6ATA) and the operation time as 60min. Set the partial pressure P of oxygen in the mixed gas according to the standard of the partial pressure P of oxygen O being 1.4 - 2.0ATA to be 1.7ATA; O for 1.7ATA;

[0036] 2) Calculate the sum of the partial pressures of nitrogen and helium P N + P He = 4.3ATA, and then combine the formula and P N ≤ 4ATA to determine that the partial pressure of helium in the mixed gas is 0.3ATA ≤ P He < 2.01ATA, and the partial pressure of nitrogen is 2.29ATA < P N ≤ 4ATA. All partial pressure values within this range can achieve the technical effects of the present invention;

[0037] 3) Further select specific partial pressure values P based on the partial pressure ranges of helium and nitrogen determined in step 2)He = 1.9 ATA, P N Perform gas distribution at 2.4 ATA, and the specific gas distribution plan under this operating condition can be obtained.

[0038] Verified by actual operation, within the environmental pressure and operation time set in this embodiment, the operators did not experience any discomfort.

[0039] After the operation is completed, decompression is carried out based on the conventional decompression plan in the art. The decompression plan determined based on the working conditions of this embodiment is a decompression depth of 30 m and a decompression time of 83 min (excluding the transfer time of 1 min between each stop). Within this decompression plan, the operators did not experience any discomfort.

[0040] Embodiment 3

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

[0042] The gas distribution method of the above mixed gas includes:

[0043] 1) Obtain the environmental pressure during operation as 6.0 bar (i.e., the total pressure of the mixed gas is 7 ATA) and the operation time as 60 min. Set the partial pressure P of oxygen according to the standard that the partial pressure P of oxygen in the mixed gas O is 1.4 - 2.0 ATA to be 1.8 ATA; O

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

[0045] 3) Further select specific partial pressure values P He = 2.3 ATA, P N = 2.9 ATA for gas distribution, and the specific gas distribution plan under this operating condition can be obtained.

[0046]

[0046] After actual operation verification, within the environmental pressure and operation time set in this embodiment, the operators did not experience any discomfort.

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

[0048] It should be noted that according to the above embodiments of the present invention, those skilled in the art can fully implement the entire scope of the independent claims and dependent claims of the present invention, and the implementation process and method are the same as those of the above embodiments; and the parts not elaborated in detail in the present invention belong to the well-known technology in the art. However, the protection scope of the present invention is not limited thereto, and any changes or substitutions that can be easily thought of by those familiar with the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention.

Claims

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

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

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, characterized in that, The total pressure P of the mixed gas is 5 ATA, and the partial pressure P O of oxygen is 1.6 ATA, and the partial pressure P N of nitrogen is 1.5 ATA, and the partial pressure P He of helium is 1.9 ATA.

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

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

7. A gas distribution method for a mixed gas used in shield operation, characterized in that, It includes the following steps: 1) Obtain the pressure of the working environment to get the total pressure P of the mixed gas, and set the partial pressure P of oxygen O to be 1.4 - 2.0 ATA; 2) According to the total pressure P of the mixed gas and the partial pressure P of oxygen O The sum of the pressures of nitrogen and helium in the mixed gas, P, is calculated N +P He =P - P O , and then combined with the formula and P N ≤ 4 ATA to determine the partial pressures of nitrogen and helium in the mixed gas.

8. The gas distribution method according to claim 7, wherein The method further includes the step of selecting specific partial pressure values within the range of the partial pressures of nitrogen and helium in the mixed gas.

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