JP2006064598A - Method and apparatus for measuring pulsation level of gas equipment and pulsation propagation prevention system using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new pulsation level measuring method and measuring apparatus capable of measuring a pulsation level generated by a gas device uniformly, easily and stably.
SOLUTION: A pulsation from a pulsation source that is a gas device is regarded as a sound pressure level, converted into acoustic energy, and the acoustic energy is used as an index for pulsation level measurement. The apparatus includes a spirally wound conduit 11 connected to the pulsation source 1, sound pressure level measuring means 12 attached to the conduit, a buffer tank 14 capable of absorbing acoustic energy caused by the pulsation, and a sound. And means 30 for converting the sound pressure measured by the pressure measuring means into acoustic energy.
[Selection] Figure 3

Description

  The present invention relates to a method and apparatus for measuring the level of pulsation generated from gas equipment, and a system for preventing pulsation propagation to a gas conduit network using the same.

  A gas conduit network such as city gas is supplied with a gas at a constant pressure from a gas supply source, and various gas equipment such as a gas combustor and a gas compressor are connected to the gas conduit network. Since the level of pulsation that occurs when these gas appliances operate is very small, it is not usually that abnormally high levels of pulsation propagate through the gas conduit network and affect other appliances.

  However, it is possible that a gas appliance with an abnormally high pulsation level will be connected to a conventional gas network by another gas operator, and if that happens, the gas at the other end will be There is also the possibility of adversely affecting equipment. In order to avoid this, it is desirable to establish a rule that prevents gas equipment with a pulsation level exceeding the reference value from being connected to the gas conduit network. In addition, since a technique for measuring stably has not been established, it is not easy to establish an effective rule.

As an apparatus for measuring the level of pulsation of the gas equipment, one as shown in FIG. 5 is conceivable. In the figure, 1 is a gas device (pulsation generation source) as a pulsation measurement object, and 2 is a gas meter. And the pipe line 3 is arrange | positioned between both, and many pressure sensors 4 are attached to the pipe line 3. FIG. The gas apparatus (pulsation source) 1 is operated by actually introducing gas, and the pulsation, that is, the time fluctuation of the pressure generated there is measured and recorded by a number of pressure sensors 4 over a certain period of time. The pulsation level can be examined by calculating the pressure fluctuation Pmax-Pmin for each position of each pressure sensor based on the result (for example, 500 Pa, 50 mmH ₂ O, etc.). When the gas device is a combustor, combustion corresponds to the operation, and when the gas device is a device such as a gas compressor, the operation corresponds to the operation.

  However, in the apparatus shown in FIG. 5, the pulsation frequency differs depending on the type of gas equipment (pulsation source) 1, so that the wavelength of the standing wave differs, the gas meter needs to be handled as an open end, and depending on the conditions It is necessary to perform tests while adjusting the pipe length by trial and error so that the pulsation level is maximized (so as to meet the resonance conditions) because clear properties such as open end and reflection end are difficult to appear. . For this purpose, it is usually necessary to prepare a pipe line linearly close to 10 m to 20 m, and it is necessary to arrange a large number of pressure sensors at intervals such as several tens of centimeters. Further, in this apparatus, since the pulsation level is compared by the same pressure fluctuation Pmax-Pmin even for different gas devices, for example, gas devices having different gas flow rates (gas consumption amounts), the influence on the gas conduit network is reduced. There is also an inconvenience that cannot be compared uniformly. Therefore, the influence on the supply network (gas conduit network) cannot be compared as a whole.

  As described above, there is an increasing need to measure the pulsation levels of various gas devices (pulsation generation sources) and compare them with the same standard regardless of the type. However, as described above, the pulsation level measurement method or apparatus currently being performed cannot effectively answer this.

  The present invention has been made in view of the circumstances as described above, and the level of pulsation generated by gas equipment that generates pulsation due to its operation, such as various gas combustors and gas compressors, is uniformly determined. It is an object of the present invention to provide a new measurement method capable of easily and stably measuring and a new measurement apparatus for carrying out the measurement method. Furthermore, an object of the present invention is to provide a system for preventing pulsation propagation to a gas conduit network constructed by using the above-described measuring device.

  The method for measuring a pulsation level of a gas device according to the present invention measures a pulsation from a pulsation generation source that is a gas device as a sound pressure level, converts the sound pressure level into a sound pressure from a definition formula of the sound pressure level, and further converts it into sound energy. The acoustic energy is used as an index for measuring the pulsation level (claim 1).

  That is, the pulsation level measurement method of the present invention directly measures, for example, a pressure fluctuation (pressure difference) generated on the upstream side of a pipeline due to pulsations generated when various gas appliances are operated, using a pressure sensor or the like. Instead, the overall sound pressure level (dB) is converted into sound pressure (Pa), and the sound pressure is converted into acoustic energy (W), which is used as an index for measuring the pulsation level. Thereby, it becomes possible to evaluate the pulsation level based on the same standard without depending on the flow rate of each gas device.

The acoustic energy (W) can be expressed by W = P × S × V (Formula 1). Here, P is the sound pressure (Pa) (N / m ² ), S is the cross-sectional area (m ² ) of the pipe, V is the speed of sound (m / s), and W = (N / m ² ) × m ² × (m / s) = N × m / s = J / s. That is, by measuring the sound pressure in the pipeline, the acoustic energy per unit time resulting from pulsation can be calculated. This is a value irrelevant to the flow rate of gas flowing through the pipeline (for example, when the gas equipment is a combustor, the amount of gas consumed by combustion), and the pulsation level is evaluated based on the same standard for various gas equipment. Is possible.

  A pulsation level measuring device for a gas appliance according to the present invention is for suitably carrying out the above method, and basically, a pipe line connected to a pulsation generation source which is a gas equipment, and the pipe is attached to the pipe line. A sound pressure measuring means; a buffer tank capable of absorbing energy caused by pulsation connected to the other end of the pipe; and a means for converting the sound pressure measured by the sound pressure measuring means into acoustic energy. It is characterized (claim 2).

  The buffer tank attached to the other end of the pipe line is arranged to absorb acoustic energy to zero, and by providing a buffer tank with a large volume, the frequency of the pulsation is increased from low to high. Can be sufficiently absorbed.

  The sound pressure measuring means can be arranged at an arbitrary position in the pipeline. One or a plurality may be arranged. It is handled as a very small attenuation, and in any case, there is no change in theory. However, a certain amount of attenuation is measured when actually measured as a real problem. By arranging a plurality of attenuations, it is possible to more accurately measure the deduction characteristics, etc. in the pipe line, and feed them back to make the actual machine more accurate. It is possible to measure the acoustic energy.

  Any means can be used as long as it can detect the sound pressure as the sound pressure measuring means, but it can cover the frequency characteristics of the fluid and pulsation used, and the frequency characteristics do not change even when the static pressure or dynamic pressure changes It is preferable that The means for converting the sound pressure measured by the sound pressure measuring means into acoustic energy is not limited as long as it can calculate Equation 1, and may be a normal microchip or the like equipped with an arithmetic circuit.

  The buffer tank is preferably one that can completely absorb sound in the entire frequency range of pulsation without causing disturbance due to reflected waves or the like. For this reason, an appropriate sound absorbing material is preferably accommodated in the buffer tank ( Claim 3). By accommodating the sound absorbing material, it is possible to achieve the intended purpose with a smaller size. Although one type of sound absorbing material may be used, it is more preferable to accommodate a plurality of types of sound absorbing materials having different sound absorbing characteristics mainly due to density in a layered combination. It is also effective to make the buffer tank box (wall surface) itself of a thin material that easily vibrates so that the extremely low frequency region can be effectively absorbed. However, it is preferable that vibration is attenuated so as not to be affected by disturbance noise.

  Any pipe can be used as long as the frequency response is known. In consideration of the case where sound cannot be completely absorbed by the buffer tank, the length of the resonance pipe or longer may be secured in order to support the pulsation level measurement at this time. However, even if a buffer tank having a high sound absorption performance is used, a considerable length is required, and in the case of a straight pipe, there is a case where it is not possible to obtain a compact size enough for practical use. Therefore, it is preferable to use a pipe having a spiral structure with a curvature within a range in which no reflection or attenuation occurs. Furthermore, the end of the pipe line having a spiral structure is opened to the buffer tank through a helical cone that spreads out acoustically and smoothly.

  Thereby, generation | occurrence | production of a reflected wave can be avoided in the connection part of a curved pipe and a buffer tank. And by making a pipe line into such a spiral structure, the compactness of an apparatus becomes still more reliable. It should be noted that the degree of curvature can be determined by calculation or experimentally in consideration of the environment in which the pulsation level measurement device is used as an actual machine, the sound absorption performance of the buffer tank, the acoustic characteristics of the pipe line, etc. Good. Further, by using a helical cone, it is possible to suppress the generation of a reflected wave more effectively at the connection portion between the pipe line and the buffer tank.

  In the present invention, the pulsation level measuring device described above is further incorporated between the gas pipe constituting the gas conduit network and the pulsation generation source which is a gas device, and the pulsation level measured by the pulsation level measuring device is Also disclosed is a pulsation propagation prevention system comprising a shutoff valve that shuts off the supply of gas to the gas appliance when a certain threshold value is exceeded (Claim 5).

  In this pulsation propagation prevention system, when a pulsation exceeding the specified value occurs due to unexpected circumstances of the gas equipment, the gas supply to the gas equipment can be shut off immediately and the operation can be stopped. It is possible to reliably prevent the pulsation from propagating.

  In the pulsation propagation preventing system described above, the present invention further includes a plurality of pulsation sources that are gas equipment connected to a gas pipe constituting the gas conduit network, and the pulsation is provided between the gas pipe and each gas equipment. A pulsation propagation preventing system is also disclosed, which includes a level measuring device and further includes control means for centrally managing information on the pulsation level measured by each pulsation level measuring device (claim 6). .

  In this pulsation propagation prevention system, when a plurality of pulsation level measuring devices detect pulsation, the position of each pulsation level measuring device, each pulsation level, characteristics of the conduit network, etc. are estimated by the control means, It is possible to quickly shut off a part close to a certain gas equipment from the gas conduit network (stop the gas supply), and even if the gas conduit network has a complicated network, pulsation is generated more effectively. Can be monitored and pulsation can be prevented from propagating.

  In the present invention, the term gas equipment is used to include various gas appliances and devices such as a gas combustor and a gas compressor, as described above. It is used as a collective term for actions for the gas equipment to achieve the original purpose of the equipment, for example, for the gas combustor, for the combustion action, and for the gas compressor, the action for compressing the gas.

  According to the method and apparatus for measuring the pulsation level of a gas device according to the present invention, it is possible to easily and stably measure the level of pulsation caused by the operation of a pulsation source that is a gas device. Therefore, when a pulsation level reference is set, the operation is facilitated, and it is possible to contribute to the development and improvement of gas equipment that does not generate pulsation.

  Moreover, by incorporating the above pulsation level measuring device into the gas conduit network, it is possible to quickly and effectively prevent the pulsation generated from a specific gas device from propagating through the gas conduit network to other gas devices. It is also possible to easily construct a pulsation propagation prevention system that can be used.

  The present invention will be described below with reference to the drawings. FIG. 1 is a conceptual diagram for explaining a pulsation level measuring method for a gas appliance according to the present invention, and FIGS. 2 and 3 show an example of a pulsation level measuring apparatus capable of implementing the above measuring method.

  In FIG. 1, reference numeral 1 denotes a gas device (pulsation generation source) for measuring a pulsation level, and the following will be described by taking a gas combustor as an example. A pulsation level measuring device 10 according to the present invention is connected to the fuel gas supply port 2 of the gas combustor 1. The pulsation level measuring device 10 has a pipe line 11 with a known acoustic characteristic connected to the fuel gas supply port 2. The length of the pipe line 11 is a length that can secure a length equal to or longer than the low-frequency pulsation resonance pipe length in consideration of general versatility when the sound absorption is not performed by the buffer tank. A sound pressure level sensor (example of sound pressure measuring means) 12 such as a microphone for measuring the sound pressure is connected. Although one microphone 12 is shown in the figure, a plurality of microphones 12 may be arranged in the pipe line 11. A helical cone 13 is connected to the other end of the conduit 11, and the expanded open end is opened to the buffer tank 14. The area of the buffer tank 14 is very large compared to the cross-sectional area of the pipe line 11, and can be regarded as substantially infinite.

  A gas supply pipe 15 branched from a gas conduit network (not shown) is connected to the buffer tank 14, and fuel gas therefrom passes through the pulsation level measuring device 10 to the gas device 1 where it is burned. When pulsation occurs during combustion of the fuel gas in the gas combustor 1, the pressure fluctuation is propagated into the pipe line and is captured as a sound pressure level by the microphone 12 provided in the pipe line 11. Further, although the acoustic energy generated by the pulsation enters the buffer tank 14 having a substantially infinite capacity, the occurrence of acoustic reflection and attenuation is avoided as much as possible by interposing the helical cone 13. The measurement by the sound pressure level sensor 12 is not substantially disturbed by a reflected wave.

All the acoustic energy is absorbed in the buffer tank 14 and becomes zero. Therefore, by multiplying the sound pressure (Pa) P (N / m ² ) measured by the sound pressure sensor 12 by the cross-sectional area S (m ² ) and the sound velocity V (m / s) of the pipe line 11, The acoustic energy W (J / s) can be calculated. Since this value is specific to the gas combustor 1 and correlates with the pulsation during combustion of the gas combustor 1, it is adopted as an index substantially equivalent to the pulsation level obtained from the conventional pressure fluctuation. can do. Further, since the value of W is not affected by the gas flow rate of the pipe line 11 (the amount of gas consumed by the gas combustor 1), the pulsation levels generated by the devices can be compared uniformly. Even in a gas conduit network in which a plurality of different gas appliances (gas combustors) are connected, the pulsation level of each gas appliance can be compared uniformly.

  If the inside of the buffer tank 14 is hollow and cannot absorb all of the acoustic energy as it is, an appropriate sound absorbing material is inserted into the high frequency region to absorb the acoustic energy. The frequency region can be absorbed using structural attenuation such as deflection of the side wall of the buffer tank 14.

  FIG. 2 shows an example of a pulsation level measuring apparatus according to the present invention, and FIG. This pulsation level measuring apparatus 10A has a stainless steel cylindrical body 14a having a diameter of about 1400 mm as a buffer tank 14, and sound absorbing materials 21a, 21b, 21c such as glass wool having different densities are laminated inside. . The upper sound-absorbing material 21a is a low-density material and can absorb a sound in a relatively high frequency range, and the middle-stage sound-absorbing material 21b has a higher density and absorbs a sound in a lower frequency range. The lowermost sound absorbing material 21c has the highest density, and exhibits a high sound absorption rate for sounds in a low frequency region. Thus, pressure loss can be kept low by not filling a large amount of uniform high-density sound-absorbing material. The sound in the lower frequency region that is not absorbed by the sound absorbing materials 21a, 21b, and 21c is absorbed by the vibration of the side wall of the stainless steel cylindrical body 14a.

  A helical cone 13 is attached to the upper end of the stainless steel cylindrical body 14a so that the expanded open end of the helical cone 13 is opened in the cylindrical body 14a. It is connected acoustically smoothly. The total height is about 2300 mm. The copper tube 11 descends downward while being spirally wound with a radius of curvature of about 950 mm, and the end 11a extends laterally in the vicinity of the upper end of the cylindrical body 14a. A sound pressure sensor 12 for measuring the sound pressure is attached in the vicinity of the end 11a as shown in FIG. The copper pipe 11 constitutes a pipe line in the present invention.

  As shown in FIG. 3, a gas device (in this example, the gas combustor 1) is connected to the end 11 a of the copper tube 11. Further, a gas supply pipe 15 is connected to the buffer tank 14, and gas from the gas supply pipe 15 passes through the cylindrical body 14 a, passes through the copper pipe 11 from the helical cone 13, and in the gas combustor 1. used. When pulsation occurs during the combustion of the gas combustor 1, the pressure fluctuation (sound pressure level) is measured by the microphone 12, which is sent to the computing device 30 and converted into acoustic energy W. As described above, the calculated acoustic energy W is acoustic energy per unit time generated by pulsation, and can be an index of pulsation level measurement.

  In FIG. 3, 31 is a normally open gas shut-off valve attached between the end 11 a region of the copper tube 11 and the gas combustor 1, and receives a signal from the arithmetic unit 30 to the gas combustor 1. Shut off the gas inflow. That is, when a numerical value that exceeds a certain threshold value is calculated by a signal from the microphone 12 (that is, when the pulsation (acoustic energy) exceeds a predetermined value), the signal is immediately sent to the gas cutoff valve 31. The gas supply to the gas device 1 is shut off. As a result, the operation (combustion) of the gas combustor 1 is stopped and the pulsation is prevented from propagating to the pulsation level measuring apparatus 10A side. As a result, it is possible to prevent the strong pulsation that passes through the buffer tank from propagating to the gas supply pipe 15, and in this pulsation propagation preventing system, the influence of the pulsation is exerted on the other gas equipment connected to the gas supply pipe 15. Can be effectively prevented. In addition, if this method is installed in a conduit connection between different gas companies, it is clear that even if different pulsation reference levels are set, it is possible to either not pulsate or not pulsate. is there.

  The above threshold value is set in consideration of the environment in which the pulsation propagation preventing system employing the pulsation level measuring method and apparatus of the gas apparatus according to the present invention is installed, the safety standard, and the like. The In the present environment, the present inventors use a gas engine that is inconvenient for actual use due to excessive fluctuations in the pulsation level that occurs during operation under any conditions, and measure the sound pressure level as a gas appliance according to the present invention. As a result, the measured sound pressure level at 2000 rpm operation was 129.52 dB (5.179 W in acoustic energy), and the measured sound pressure level at 1400 rpm operation was 137.19 dB (12.52 W in acoustic energy). From this, it is estimated that the threshold value of the acoustic energy when the pulsation propagation preventing system according to the present invention is adopted in a normal gas conduit network is, for example, about 5.5 W or less.

  FIG. 4 shows another example of the pulsation propagation preventing system according to the present invention. Here, a plurality of gas devices (in this example, gas combustors) 1... Are connected to the gas pipes constituting the gas conduit network 51, and between the gas pipes and the gas combustors 1. The pulsation level measuring device 10A and the gas shut-off valve 31 described above are incorporated. A signal from each microphone 12 attached to each pulsation level measuring device 10A is sent to a central control means (not shown) and processed.

  In the central control means, when a plurality of pulsation level measurement devices (for example, three pulsation level measurement devices surrounded by S in FIG. 4) detect pulsation, the positions of the pulsation level measurement devices, the pulsation levels, the conduit network The signal of shutting off one or a plurality of gas shut-off valves closest to the pulsation source is issued, and that portion is shut off from the gas conduit network (gas supply is stopped). By adopting such a centralized control system, it is possible to more effectively monitor the occurrence of pulsation and prevent the pulsation from propagating, even in a gas pipeline network that has a complex network. It becomes.

The conceptual diagram for demonstrating the pulsation level measuring method of the gas equipment by this invention. The figure which shows an example of the pulsation level measuring apparatus for enforcing the measuring method by this invention. It is a figure explaining an example of the pulsation propagation prevention system by the present invention, and a pulsation level measuring device is shown in a part section. The conceptual diagram for demonstrating the other example of the pulsation propagation prevention system by this invention. The figure which shows an example of the apparatus in the case of obtaining the pulsation level of gas equipment from an actual pressure fluctuation.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Pulsation generation source (gas apparatus which is going to measure a pulsation level), 2 ... Fuel gas supply port, 10, 10A ... Pulsation level measuring device, 11 ... Pipe line (stainless steel pipe), 11a ... End part of stainless steel pipe, DESCRIPTION OF SYMBOLS 12 ... Microphone (sound pressure level measuring means), 13 ... Helical cone, 14 ... Buffer tank, 15 ... Gas supply pipe branched from gas conduit network, 21a, 21b, 21c ... Sound absorption material, 30 ... Arithmetic unit, 31 ... Gas Shut-off valve

Claims (6)

  Pulsation from a pulsation source that is a gas device is measured as a sound pressure level, converted into sound pressure from a sound pressure level definition formula, converted into sound energy, and the sound energy is used as an index for pulsation level measurement. A pulsation level measuring method for a gas appliance.   A pipe connected to a pulsation source which is a gas device, a sound pressure measuring means attached to the pipe, a buffer tank capable of absorbing acoustic energy caused by pulsation connected to the other end of the pipe, and a sound pressure A pulsation level measuring device for a gas appliance, comprising: at least means for converting sound pressure measured by the measuring means into acoustic energy.   The pulsation level measuring device for a gas appliance according to claim 2, wherein the buffer tank includes a sound absorbing material.   4. The gas appliance according to claim 2, wherein the pipe has a portion having a spiral structure, and the portion having the spiral structure opens to the buffer tank via a helical cone. Pulsation level measuring device.   The pulsation level measuring device for a gas appliance according to any one of claims 2 to 4 is incorporated between a gas pipe constituting the gas conduit network and a pulsation generation source which is a gas appliance, A pulsation propagation preventing system comprising: a shut-off valve that shuts off gas supply to the pulsation generation source when the pulsation level measured by the pulsation level measuring device exceeds a certain threshold value.   A plurality of pulsation sources, which are gas equipment, are connected to the gas pipes constituting the gas conduit network, and a pulsation level measuring device is incorporated between the gas pipe and each of the plurality of pulsation sources, 6. The pulsation propagation preventing system according to claim 5, further comprising control means for centrally managing information on the pulsation level measured by each pulsation level measuring device.

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