JP4874196B2 - Sealing evaluation method for high-pressure fluid storage facilities - Google Patents

Description

  The present invention relates to a method for evaluating the sealing property of a high-pressure fluid storage facility for evaluating the sealing property of a storage tank of a high-pressure fluid storage facility that stores fluid under high pressure.

  Conventionally, as a facility for storing a gas (fluid) such as natural gas under high pressure, for example, a high-pressure gas storage facility in a rock mass (high-pressure fluid storage facility) is known (see, for example, Patent Document 1). And this high-pressure gas storage facility in the rock mass, for example, excavates the rock mass to form a cavity, coats the inner wall surface of this cavity with a lining material, and backfill material (backfilling between the inner wall surface and the lining material) A concrete storage tank or a buffer material is interposed, and a storage tank for storing high-pressure gas such as natural gas is formed in the space inside the lining material. In addition, an access tunnel connecting the storage tank and the ground surface is provided, and this access tunnel is used as a work passage when constructing the storage tank, a maintenance passage after operation, a laying passage for piping for high-pressure gas transportation, etc. . Furthermore, a pressure-resistant plug for ensuring the airtightness of the storage tank is disposed at a connection portion of the access tunnel with the storage tank, and a manhole, a pipe for transporting high-pressure gas, and the like are incorporated in the pressure-resistant plug as necessary.

  Also, in this type of high-pressure gas storage facility in bedrock, the presence or absence of high-pressure gas leakage was confirmed during operation. For example, a gas detector was installed and leaked from the storage tank outside the lining material and backfill material. High pressure gas is detected, optical fiber is laid, and the displacement (strain) when cracks occur in the lining material and backfill material, and temperature change due to leakage of high pressure gas are detected. The presence or absence of gas leakage is confirmed. In addition, visual inspections and non-destructive inspections (penetration inspection, magnetic particle inspection, ultrasonic inspection, etc.) are performed during periodic inspections of the high-pressure gas storage facility in the bedrock to check for defects such as cracks in the lining material. Like to do.

  On the other hand, it may be difficult to directly detect the leaked gas on the outer periphery side of the storage tank with a gas detector or the like, or the lining material may not be inspected by nondestructive inspection. In addition, this type of high-pressure gas storage facility (storage tank) in the rock is generally large-scale, and therefore requires a lot of work time and cost for visual inspection and non-destructive inspection.

  For this reason, for example, at the time of periodic inspection of the high pressure gas storage facility in the rock mass, the valve of the piping for high pressure gas transportation is closed and shut off, the circulation of the high pressure gas stored in the storage tank is stopped and kept in a sealed state, In some cases, the gas pressure and temperature in the storage tank are measured over time (in time series) to check (evaluate) the airtightness of the storage tank. In this airtightness inspection method (airtightness evaluation method), by using the Boyle-Charles law or the ideal gas equation of state obtained from the Boyle-Charles law and Avogadro's law, the presence or absence of high-pressure gas leakage is checked. It is possible to confirm (evaluate the airtightness of a large-scale storage tank) by a simple operation of measuring gas pressure and gas temperature.

  That is, when Boyle-Charles' law is used, the initial value of the gas pressure, gas temperature, and gas volume (reservoir volume) in the storage tank from the relationship that the gas volume is inversely proportional to the gas pressure and proportional to the gas temperature. When the gas volume is calculated from the gas pressure and gas temperature measured over time, and the calculated gas volume increases over time with respect to the initial gas volume, it can be evaluated that leakage has occurred.

When the ideal gas equation of state is used, the gas pressure, gas temperature and gas volume (storage tank volume) are measured, and the amount of gas substance (number of moles: n) stored in the storage tank, and thus the gas mass M _T (M _T = nM; M is the mass of 1 mol of gas) is obtained, and the time change of the gas mass is captured, and it can be evaluated that leakage occurs when the gas mass decreases with time.
JP 2004-83244 A

  However, according to the Boyle-Charles law and the ideal gas equation of state obtained from the Boyle-Charles law and Avogadro's law, it depends on the type of actual gas (real gas) stored in the storage tank. In particular, the more the gas is stored at low temperature and high pressure, the more the proportion of gas molecules in the gas volume cannot be ignored, the size of the gas molecules affects, and the intermolecular force acting between the gas molecules. As a result, there is a problem that it is not possible to evaluate the leakage of high-pressure gas accurately because it deviates from the ideal gas law.

  In view of the above circumstances, the present invention is a method for evaluating the tightness of a high-pressure fluid storage facility capable of measuring the pressure and temperature of a high-pressure fluid stored in a storage tank in a time series and accurately evaluating the sealing performance of the storage tank. The purpose is to provide.

  In order to achieve the above object, the present invention provides the following means.

  The method for evaluating the sealing property of a high-pressure fluid storage facility according to the present invention is a method for evaluating the sealing property of a storage tank of a high-pressure fluid storage facility for storing a fluid under high pressure, which is a function of the critical pressure and the critical temperature of the fluid. Applying the equation of state of the fluid into which the compression coefficient expressed in the form is applied, the fluid mass in the storage tank is obtained based on at least the fluid pressure and fluid temperature in the storage tank measured in time series, and the storage tank The airtightness of the storage tank is evaluated by capturing time-series fluctuations in fluid mass.

  In the present invention, by introducing a compression coefficient in a function form according to the fluid (real fluid) stored in the storage tank and using a fluid state equation having nonlinearity according to the fluid pressure and fluid temperature, The fluid mass in the storage tank can be obtained by reflecting the influence of the size and intermolecular force acting between the fluid molecules, and the fluid mass in the storage tank can be obtained with high accuracy over a wide range of pressures and temperatures. Thereby, it becomes possible to accurately evaluate the airtightness of the storage tank by capturing time-series fluctuations of the fluid mass in the storage tank.

  In the method for evaluating the tightness of the high-pressure fluid storage facility according to the present invention, it is desirable to determine the fluid mass in the storage tank by reflecting the change in the storage tank volume according to the internal pressure fluctuation of the storage tank.

  In this invention, the change in the storage tank volume corresponding to the internal pressure fluctuation of the storage tank is measured in time series, and the change in the storage tank volume is reflected in the fluid equation of state, thereby obtaining the fluid mass in the storage tank with higher accuracy. This makes it possible to more accurately evaluate the tightness of the storage tank.

  Furthermore, in the method for evaluating the tightness of the high-pressure fluid storage facility according to the present invention, not the fluid to be stored in the high-pressure fluid storage facility but the fluid having a known functional form of the compression coefficient is stored in the storage tank, and the known fluid You may make it evaluate the sealing performance of the said storage tank using.

  In the present invention, for example, when evaluating the sealing performance of a storage tank for a high-pressure fluid storage facility for storing a gas (storage target fluid) such as natural gas, which is a combustible gas having a known compression coefficient function, For example, it is possible to evaluate the sealing performance of the storage tank relatively safely and easily by storing a known fluid such as air that has a known compression function and is easy to handle and safe. It becomes possible. On the other hand, even when storing fluid with unknown composition or fluid with unknown compression coefficient function, the storage tank is similarly sealed by storing the fluid with known compression coefficient and evaluating the sealing performance of the storage tank. It becomes possible to evaluate sex.

  According to the method for evaluating the tightness of a high-pressure fluid storage facility according to the present invention, by using a state equation of a fluid in which a compression coefficient of a function type corresponding to a fluid (real fluid) stored in a storage tank is used, Compared with the evaluation method using the equation of state, the fluid mass in the storage tank can be obtained with high accuracy over a wide range of pressures and temperatures. It becomes possible to accurately evaluate sex. As a result, it is possible to accurately evaluate the presence or absence of fluid leakage from the storage tank.

  Hereinafter, with reference to FIG. 1 to FIG. 6, a sealing evaluation method for a high-pressure fluid storage facility according to an embodiment of the present invention will be described. The present embodiment relates to a method for evaluating the airtightness of a storage tank of a high-pressure gas storage facility in a rock that stores a gas (fluid) such as natural gas under high pressure.

  First, as shown in FIG. 1, the high-pressure gas storage facility (high-pressure fluid storage facility) A in the rock according to the present embodiment excavates the rock G to form a substantially elliptical cross section, and the inner wall surface ( It is constructed by covering the bedrock G surface) with a steel lining material (airtight material) 1 and interposing a backfill material (backfill concrete) 2 and a buffer material (not shown) between the inner wall surface and the lining material 1. ing. A storage tank 3 having a substantially elliptical cross section for storing a gas such as natural gas (high pressure gas, fluid) is formed in a space inside the lining material 1. In addition, an access tunnel 4 for connecting the storage tank 3 and the ground surface is provided, and a pressure-resistant plug 5 for securing the airtightness of the storage tank 3 is disposed at a connection portion between the access tunnel 4 and the storage tank 3. A manhole 6 and a high-pressure gas transportation pipe (not shown) are incorporated in the pressure-resistant plug 5.

  FIG. 2 is a plan sectional view of the high-pressure gas storage facility A in the rock mass, and FIG. 3 is a longitudinal sectional view of the high-pressure gas storage facility A in the rock mass. In this embodiment, these are shown in FIGS. As described above, two pressure gauges 7 and eight thermometers 8 for measuring the pressure and temperature of the gas stored in the storage tank 3 are installed in the storage tank 3, respectively. Furthermore, the light for storage tank strain measurement of 3 survey lines along the surface of the bedrock G, 3 survey lines along the unshown reinforcing bar arranged on the inner peripheral surface side of the backfill material 2, and 4 survey lines along the inner peripheral surface of the lining material 1 Fibers 9a, 9b, and 9c are disposed, and an internal displacement meter 10, a rock displacement meter 11, a manhole relative displacement meter 12, and a pressure-resistant plug absolute displacement meter 13 are disposed in the reservoir 3, the rock G, and the like, respectively. Yes.

  And when evaluating the airtightness of the storage tank 3 with respect to the high-pressure gas storage facility A in the above-mentioned rock mass, in this embodiment, with respect to the gas (real gas) stored in the storage tank 3 under high pressure, the pressure gauge 7 And thermometer 8 respectively measure the gas pressure and gas temperature (fluid pressure and fluid temperature) in time series, and based on the measured values, instead of using the ideal gas equation of state as in the past, the compression coefficient By calculating the gas mass in the storage tank 3 by applying the equation of state of the real gas (in which the fluid is introduced), and capturing the time-series fluctuations of the gas mass in the storage tank (fluid mass in the storage tank), The presence or absence of gas leakage from the storage tank 3, that is, the airtightness of the storage tank 3 is evaluated.

  Specifically, in this embodiment, as shown in the equation (1), a state equation of a real gas into which a compression coefficient Z is introduced is used. Here, P is a gas pressure, V is a gas volume (storage tank volume) per mole, T is a gas temperature, and R is a gas constant.

Further, in the present embodiment, the compression coefficient Z is expressed by the relative value (against the critical temperature Tr) of the gas temperature T and the critical temperature Tc shown in the equation (3) and the equation (4), as shown in the equation (2). The function f is expressed as a function of the relative value of the gas pressure P and the critical pressure Pc (versus the critical pressure Pr). The function f is a function determined experimentally according to the gas composition, as shown in Reference 1, for example. It is. The critical temperature Tc and the critical pressure Pc are known amounts that have already been obtained according to the gas composition (for each substance constituting the gas).
[Reference 1] Nelson, LC, and EFObert: Trans. ASME, 76, 1057, [1954]

  And since the compression coefficient Z changes as a function f corresponding to the gas temperature T and the gas pressure P (according to the critical temperature Tr and the critical pressure Pr) instead of a constant value in this way, Unlike the equation of state of the real gas shown in Equation (1), the relationship between the PV on the left side and the RT on the right side is nonlinear, and the magnitude of the gas molecule is determined by experimentally obtaining the function form of the compression coefficient Z. It is possible to reflect the influence of interstitial forces acting between gas molecules.

On the other hand, when the gas molecules are not perfectly spherical but eccentric, the intermolecular force is affected. Therefore, in this embodiment, in consideration of this point, Reference Document 2, Reference Document 3, and Reference Document 4 The compression coefficient Z is obtained using the equation (5) shown. Here, Z ⁽⁰⁾ is a function of the critical temperature Tr and the critical pressure Pr in a spherical gas molecule, and Z ⁽¹⁾ is a function of the critical temperature Tr and the critical pressure Pr in an eccentric gas molecule. Equation (5) represents gas molecules divided into two types of components depending on the presence or absence of eccentricity. Further, ω is an eccentric factor defined by the equation (6), and is obtained using the steam pressure Pvpr = P / Pc when Tr = 0.7. Therefore, in order to obtain the eccentric factor ω, it is necessary to obtain the vapor pressure Pvpr, but practically, the eccentric factor ω of various substances already constituting the gas is experimentally obtained for many kinds of substances. So you can use them.
[Reference 2] Pitzer, KS, and RFCurl: J. Am. Chem. Soc., 77, 3427, [1955]
[Reference 3] Pitzer, KS, and RFCurl: J. Am. Chem. Soc., 79, 2369, [1957a]
[Reference 4] Pitzer, KS, and RFCurl: The Thermodynamic Properties of Fluids, Inst, Mech. Eng., London, [1957a]

In addition, the BWR (Benedict-Webb-Rubin) equation is used as an equation representing the state quantities of fluids in a wide range of temperatures and pressures, and this BWR equation is further modified to take into account the eccentric factor ω in equation (5). Equation (7) is shown in Reference 5.
[Reference 5] Lee, BI, and MGKesler: AIChE J., 21,510, [1975]

In the present embodiment, the constant (ie, Tr = T / Tc) and pressure (ie, Pr = P / Pc) desired to be obtained from the equation (7) using the constants related to the simple fluid (spherical gas molecules) shown in Table 1. ) As a condition (known number), the critical volume Vr ⁽⁰⁾ of a simple fluid (spherical), which is the only unknown, is obtained.

Next, the compression coefficient Z ⁽⁰⁾ of the simple fluid (spherical shape ⁾ is calculated from the equation (8) using the obtained Vr ⁽⁰⁾ .

Next, using the same critical temperature Tr and critical pressure Pr as in the case of obtaining Vr ⁽⁰⁾ in the above equation (7), the constants of the reference fluid having eccentricity in the gas molecules shown in Table 1 are applied. The critical volume Vr ^(R) of the reference fluid is obtained from the equation (9). That is, using the constants of the reference fluid in Table 1, the solution of Vr ^(R) , which is the only unknown, is obtained by Equation (9) using the constants of the reference fluid.

Then, using the obtained Vr ^(R) , the compression coefficient Z ^(R) of the reference fluid is calculated from the equation (10).

Next, from the simple fluid compression coefficient Z ⁽⁰⁾ , the reference fluid compression coefficient Z ^(R) obtained by the equations (7) and (10), and the gas eccentricity factor ω to be obtained, the equation ( 11), the compression coefficient Z is obtained. The formula (11) is a specific example of the formula (5).

Using the compression coefficient Z obtained by the above equation (11), the gas volume V of 1 mol at the gas temperature T and gas pressure P to be obtained from the equation (1) can be obtained, and the obtained 1 mol of gas. From the relationship between the volume V and the storage tank volume V _T , the number of moles n of the gas in the storage tank 3 in a state where there is no leakage, and the gas mass M _T in the storage tank 3 can be converted by the equations (12) and (13). . Here, M is 1 molar mass of gas.

And when evaluating the airtightness of the storage tank 3 for the high pressure gas storage facility A in the rock mass, it is measured in time series by the pressure gauge 7 and the thermometer 8 installed in the storage 3 of the high pressure gas storage facility A in the rock mass. using the measured value of the gas pressure P and the gas temperature T, and calculates the number of moles n thus gas mass M _T of the gas, to confirm the presence or absence of the time-series variation of gas mass M _T of the calculated gas . That is, the gas temperature T and the gas pressure P in the reservoir 3 chronologically measured, when the converted value of the gas mass M _T in the storage tank 3 has been confirmed that no change over time (time series) is evaluated that there is no gas leakage from inside the reservoir 3, when the converted value of the gas mass M _T is decreased over time, the gas leaks from the reservoir within 3, airtightness of the reservoir 3 is compromised It is evaluated that it is.

  Next, the airtightness test of the storage tank 3 of the in-bed rock high-pressure gas storage facility A shown in FIGS. 1 to 3 is performed by the airtightness evaluation method of the present embodiment and the airtightness evaluation method by the conventional ideal gas equation of state, respectively. An example is shown, and the effect of the airtightness evaluation method for the high-pressure gas storage facility A of the present embodiment will be described. Here, for the storage tank 3 in which airtightness is ensured, that is, the storage tank 3 in which no gas leaks, the airtightness evaluation method of the present embodiment and the airtightness evaluation method based on the conventional ideal gas equation of state are respectively used. The result of the test is shown.

  Furthermore, when the high-pressure gas storage facility A in the rock is constructed, for example, when the gas to be stored (fluid to be stored) such as natural gas is stored in the storage tank 3, the airtightness of the storage tank 3 is evaluated. Assuming that the airtightness of the storage tank 3 is evaluated during periodic inspection of the internal high-pressure gas storage facility A, air (known fluid) is stored in the storage tank 3 instead of the storage target gas, and the storage tank 3 is used using this air. We will explain the evaluation of airtightness. That is, the storage tank is not a fluid to be actually stored in the storage tank 3 but air that is easy to handle and safe and has a known function form of the compression coefficient Z, unlike natural gas which is a combustible gas. The evaluation of the airtightness of 3 will be described as an example.

  First, air is sent from the piping for high-pressure gas transportation to the storage tank 3, the pressure P in the storage tank 3 is increased to 20 MPa, the valve of the piping is closed and shut off (shut-in), and the air pressure P in the storage tank 3 is The measurement of the air temperature T is started.

  Here, FIG. 4 shows the pressure P and temperature T in the storage tank 3 over time from the start of shut-in to the end of shut-in (the state where the valve of the pipe is closed and the valve of the pipe is opened). The measurement results are shown. And as shown in this figure, the temperature T in the storage tank 3 rises by sending compressed air in the storage tank 3 until just before the start of shut-in, and the temperature T in the storage tank 3 after the start of the shut-in is relatively high. It gradually decreases with the passage of time due to the effect of heat conduction outside the storage tank 3. Further, the pressure P during the shut-in gradually decreases as the temperature T decreases. The temperature T shown here is an average value of the temperatures T measured by the eight thermometers 8 in the storage tank 3, and the temperature T in the storage tank 3 is caused by convection immediately after shut-in. A temperature difference of about 3 ° C. occurs between the temperature T at the bottom of 3 and the temperature T at the top of the storage tank 3, and this temperature difference gradually decreases with time. For this reason, since an average temperature may cause an error as a representative value of the temperature representing the state quantity of the entire storage tank 3, it is necessary to perform measurement until the temperature distribution in the storage tank 3 settles to a steady state.

Then, using the measurement value of the thus measured were storage tank pressure P and storage tank temperature T, but a first molar volume V of the air in the storage tank 3, the air mass M _T in the reservoir 3 from the reservoir volume V _T calculated to evaluate the airtightness with the absence time series variation (temporal decrease) is secured to the air mass M _T.

At this time, in the airtightness evaluation method according to the present embodiment, first, the air used in the airtightness test is a mixture of approximately 79% nitrogen, 21% oxygen, and 1% or less of components other than nitrogen and oxygen. Since it is a gas, Dalton's law is applied to each measured value of the air pressure P measured in time series, and the partial pressure P _{N2 of} nitrogen and the partial pressure P _{O2 of} oxygen are expressed by the equations (14) and (15 ) Note that components other than nitrogen and oxygen are negligible and are ignored.

Then, in place of the pressure P of the mixed gas, the equations (1) to (13) are applied to the nitrogen partial pressure P _N2 and the oxygen partial pressure P _O2 , respectively, so that the nitrogen storage mass M _{T ( N2)} and oxygen storage mass M _{T (O2)} are calculated respectively. The nitrogen storage mass M _{T (N2)} and the oxygen storage mass M _{T (O2)} calculated in this way are summed as shown in Equation (16) to obtain the air storage mass M _T. determining the time change of the storage tank mass M _T. At this time, in the present embodiment, the air mass M _T in the storage tank is obtained in consideration of the change in the storage tank volume V _T according to the internal pressure fluctuation of the storage tank 3. That is, the optical fiber 9a, 9b, using the measurement value measured by 9c and various displacement meter 10 and 11, and to reflect the time variation of the reservoir volume V _T due to internal pressure increases, and nitrogen from the equation (12) The number of moles n in the storage tank of each component of oxygen is obtained, and the masses M _{T (N2)} and M _{T (O2)} of nitrogen and oxygen in the storage tank 3 are obtained from the equation (13). and calculates the mass _{M T.}

Figure 5 shows the measured pressure P and temperature T every 4 hours, the time variation of the reservoir within the air mass M _T calculated in airtightness evaluation method of this embodiment. Then, as shown in FIG. 5, after the start of shut-in, the storage tank is maintained while the temperature distribution in the storage tank 3 is not in a steady state due to the influence of air convection or the effect of heat conduction from the storage tank 3 to the rock mass G. variation occurs in the inner air mass M _T, but with the temperature distribution in the reservoir 3 and after some time a steady state, the variation of the reservoir within the air mass M _T is eliminated. That is, while the temperature distribution in the storage tank 3 is not in the steady state, the storage tank air mass M _T over time is observed downward tendency to decrease, this lowering the temperature distribution in the storage tank 3 is in a steady state The tendency disappears.

Thereby, in the airtightness evaluation method of this embodiment, the time change of the air mass M _T in the storage tank calculated using the measured values of the pressure P and the temperature T after the temperature distribution in the storage tank 3 is stabilized is captured. , when there is no temporal change in the storage tank air mass M _T as shown in Figure 5, airtight reservoir 3 is secured, the gas can be evaluated not to be leaked. Also, if there is a change the temperature distribution in the reservoir 3 continues to decrease stable storage tank air mass M _T even after it has been confirmed, it can be evaluated from the reservoir 3 and the gas is leaked.

On the other hand, FIG. 6 shows the time change of the air mass M _T in the storage tank obtained by the conventional equation of state of ideal gas using measured values of the pressure P and temperature T in the storage tank 3 similar to FIG. Also in this conventional method, Dalton's law is applied, and the partial pressure P _{N2 of} nitrogen and the partial pressure P _{O2 of} oxygen are obtained from the equations (14) and (15). Based on this, the number of moles n _N2 and n _O2 of nitrogen and oxygen are obtained by the equations (17) and (19) assuming an ideal gas, respectively, and the air mass M _{T (N2)} and M _T in the nitrogen and oxygen storage tanks are obtained. _(O2) is obtained by Equation (18) and Equation (20), respectively. The nitrogen storage tank mass _{M T (N2),} oxygen storage tank mass _{M T (O2)} into equation (16), seeking storage tank air mass _{M T} by the ideal gas equation.

And in this conventional method, as shown in FIG. 6, even when it calculates using the measured value of the pressure P and temperature T after the temperature distribution in the storage tank 3 was stabilized, the airtightness of the storage tank 3 is ensured. However, the air mass M _{T in the} storage tank decreases with time and continues to fluctuate, making it impossible to accurately evaluate the presence or absence of gas leakage.

Therefore, in the airtightness evaluation method (high-pressure fluid storage facility sealing property evaluation method) of the rock mass high-pressure gas storage facility A of the present embodiment, the function type according to the gas (fluid, real fluid) stored in the storage tank 3 is used. By introducing the compression coefficient Z and using the equation of state of the real gas with nonlinearity according to the gas pressure P and gas temperature T, the influence of the intermolecular force acting on the size of the gas molecules and the gas molecules is reflected. Te can be obtained a gas mass M _T in the tank 3, it is possible to determine the gas mass M _T accurately storage tank 3 over a wide range of pressure P and temperature T. Thus, by capturing the sequence variation when storage tank gas mass M _T, it is possible to accurately evaluate the airtightness of the storage tank 3.

Also, as in the present embodiment, by determining the storage tank the gas mass M _T taking into account the variation of the reservoir volume V _T corresponding to the internal pressure change of the reservoir 3, i.e., the reservoir volume corresponding to pressure fluctuations in the reservoir 3 By measuring the variation of V _T in time series and reflecting the variation of the storage tank volume V _T in the state equation of the actual gas, the gas mass M _T in the storage tank 3 can be obtained more accurately. It becomes possible to more accurately evaluate the airtightness of the.

  Furthermore, instead of the gas to be stored in the high-pressure gas storage facility in the rock mass (combustible gas such as natural gas), another gas (air) having a known function form of the compression coefficient Z is stored in the storage tank 3, and this air is stored. By using and evaluating the airtightness of the storage tank 3, it becomes possible to evaluate the airtightness of the storage tank 3 relatively safely and easily. Further, even when storing a fluid whose composition is unknown or a fluid whose compression coefficient Z is unknown, a gas (air) whose compression coefficient Z is known is stored in the storage tank 3 and this air is used. By evaluating the airtightness of the storage tank 3, it becomes possible to evaluate the sealing performance of the storage tank 3.

Therefore, according to the airtightness evaluation method for the high-pressure gas storage facility A in the rock according to the present embodiment, compared with the conventional evaluation method using the ideal gas equation of state, the pressure P and the temperature T over a wide range are accurate. it is possible to obtain the gas mass M _T in the reservoir 3, by capturing the sequence variation when storage tank gas mass M _T, it becomes possible to accurately evaluate the airtightness of the reservoir 3, reservoir 3 It is possible to accurately evaluate the presence or absence of gas leakage from.

  As mentioned above, although embodiment of the sealing evaluation method of the high pressure fluid storage facility concerning the present invention was described, the present invention is not limited to the above-mentioned one embodiment, and can be suitably changed in the range which does not deviate from the meaning. is there. For example, in the present embodiment, the high-pressure fluid storage tank facility has been described as the high-pressure gas storage facility A in the rock built in the rock, but the sealing evaluation method for the high-pressure fluid storage facility according to the present invention is as follows. The present invention can be applied to the evaluation of hermeticity of all storage tanks 3 that store fluid under high pressure, and is not particularly limited to application to the high-pressure gas storage tank facility A in the rock.

Further, in this embodiment, it is assumed to tank 3 to store the gas (fluid) has been described for evaluating the tightness of the reservoir 3 by capturing the temporal change in gas mass M _T of the gas The method for evaluating the tightness of the high-pressure fluid storage facility according to the present invention is not limited to the application to the hermeticity evaluation of the high-pressure gas storage facility, and the present embodiment uses Formula (1) to Formula (13). Similarly, the present invention can be widely applied to liquids (fluids) stored under high pressure and fluids in a critical state having no gas-liquid phase boundary.

Furthermore, in this embodiment, in evaluating the sealing property of the storage tank 3, not the fluid to be stored in the high-pressure fluid storage facility (the gas to be stored such as natural gas in the high-pressure gas storage facility A in the rock mass) but the compression coefficient Z of but functional form is assumed to perform tightness evaluation stored known fluid (air) to the storage tank 3, obtains the fluid mass M _T of the fluid storage target, time change of the fluid mass M _T of the storage target Of course, the sealing performance of the storage tank 3 can be evaluated in the same manner as in the present embodiment. Further, even if a known fluid is used instead of the fluid to be stored, the known fluid need not be limited to air.

Moreover, in this embodiment, when performing airtightness evaluation of a storage tank using the air of the mixed gas which consists of nitrogen, oxygen, and another trace component, Dalton's law is applied and nitrogen partial pressure _PN2 and oxygen of The partial pressure P _O2 is obtained from the equations (14) and (15), and instead of the mixed gas pressure P, the partial pressure P _{N2 of} nitrogen and the partial pressure P _O2 of _oxygen are respectively calculated from the equations (1) to (1). storage tank mass (13) is applied to the nitrogen _{M T (N2)} and oxygen storage tank mass _{M T} a _(O2) were calculated, and summing these (equation (16)) storage tank air mass _{M T} is calculated, it is assumed that evaluates the airtightness of the storage tank 3 captures the time variation of the reservoir within the air mass M _T, when performing sealing assessment and stored in this way the fluid mixture in the reservoir 3 , And calculate the mass in the reservoir of one component constituting the mixed fluid (for example, the mass M _{T (N2)} in the nitrogen reservoir ₎ The sealing property of the storage tank 3 may be evaluated by grasping the time change of the mass of the one-component storage tank.

It is a figure which shows the high pressure fluid storage tank facility (high-pressure gas storage facility in bedrock) which concerns on one Embodiment of this invention. It is a plane sectional view of the high-pressure fluid storage tank facility (high-pressure gas storage facility in bedrock) concerning one embodiment of the present invention. It is a longitudinal cross-sectional view of the high-pressure fluid storage tank facility (high-pressure gas storage facility in bedrock) concerning one embodiment of the present invention. It is a figure which shows the time change of the pressure in a storage tank, and temperature. It is a figure which shows the time change of the air mass in a storage tank calculated using the sealing performance evaluation method of the high pressure fluid storage tank facility which concerns on one Embodiment of this invention. It is a figure which shows the time change of the air mass in a storage tank computed using the conventional sealing evaluation method.

Explanation of symbols

1 Lining material (airtight material)
2 Backfill 3 Storage tank 4 Access tunnel 5 Pressure plug 6 Manhole 7 Pressure gauge 8 Thermometer 9a Optical fiber 9b Optical fiber 9c Optical fiber 10 Air displacement meter 11 in the storage tank 11 Rock displacement meter 12 Manhole relative displacement meter 13 Pressure plug absolute displacement meter A High pressure gas storage facility in rock (high pressure fluid storage facility)
G bedrock

Claims (3)

A method for evaluating the tightness of a storage tank of a high-pressure fluid storage facility for storing fluid under high pressure,
Based on at least the fluid pressure and the fluid temperature in the storage tank measured in time series by applying a fluid equation of state that introduces a compression coefficient represented by a function form of the fluid critical pressure and the critical temperature. A method for evaluating the sealability of a high-pressure fluid storage facility, wherein the fluid mass in the storage tank is obtained, and the hermeticity of the storage tank is evaluated by capturing time-series fluctuations in the fluid mass in the storage tank. In the high-pressure fluid storage facility sealing evaluation method according to claim 1,
A method for evaluating the sealing property of a high-pressure fluid storage facility, wherein the mass of the fluid in the storage tank is obtained by reflecting a change in the storage tank volume according to the internal pressure fluctuation of the storage tank. In the sealing evaluation method of the high-pressure fluid storage facility according to claim 1 or 2,
The high-pressure fluid storage facility stores not a fluid to be stored, but a fluid having a known function form of the compression coefficient in the storage tank, and uses the known fluid to evaluate the sealing performance of the storage tank. Method for evaluating the tightness of fluid storage facilities.

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