JP4742548B2 - Method and apparatus for monitoring a liquefied gas tank - Google Patents

Description

  The present invention relates to a monitoring method and a monitoring device for monitoring liquid temperature, liquid level, pressure, etc. when a liquefied gas tank is filled with liquefied gas, or for monitoring liquid temperature, liquid level, pressure, etc. in a tank after filling. Is.

  When filling a tank with liquefied natural gas (LNG) or other liquefied gas, monitor the liquid level of the liquefied gas, or the liquid temperature and pressure in the tank, for safe and proper filling. It is necessary to monitor the state in the tank such as the liquefied gas liquid level in the tank, the pressure in the tank, and the liquid temperature after filling.

  Conventionally, there is a liquefied gas filling system disclosed in Patent Document 1. In Patent Document 1, the temperature of the liquefied gas is detected by a temperature sensor as a parameter for controlling the filling state, and the pumping pressure of the pump is based on the detected liquid temperature. Is controlling.

  Further, Patent Document 2 discloses a method for measuring a filling level using a conventional pressure as a parameter. In the conventional filling level measuring method disclosed in Patent Document 2, a difference between a pressure in a tank and a pressure in a reference device is disclosed. The pressure is detected, and the filling level is detected based on the differential pressure.

  As described above, when filling a tank with liquefied gas, in order to monitor the state in the tank after filling, a sensor such as a pressure sensor or a temperature sensor is required. By providing a plurality of sensors and making them redundant, reliability is improved.

  However, when there is a restriction on installation, for example, a tank for storing liquid fuel, such as a rocket, has a space restriction and a weight restriction, and a duplicate sensor is not provided. In such a monitoring system using a single sensor, the reliability of the monitoring system greatly affects the reliability of the sensor alone. Further, in the monitoring system using a single sensor, when the sensor indication value indicates an abnormality, it is not possible to determine whether the sensor itself is normal or abnormal. Therefore, it is impossible to determine whether the sensor itself is faulty or the tank system or other equipment is abnormal, and it is impossible to continue the work while filling the liquefied gas, and the work must be stopped. If the operation of the facility cannot be stopped immediately during supply, etc., it may not be possible even if the indicated value of the sensor indicates an abnormality.

JP 2001-248792 A

JP-A-10-170384

  In view of such circumstances, the present invention is intended to improve the accuracy of monitoring normality and abnormality of a sensor in a monitoring system using a single sensor, and to enable operation of equipment even when the sensor is abnormal.

  The present invention relates to a data table in which at least one of the temperature and pressure in the tank is associated with the liquid level of the tank, calculates the liquid level of the tank from the outside air temperature and the supply pressure of the liquefied gas, and calculates the calculated liquid level of the tank And a calculated value for at least one of the temperature and pressure in the tank based on the data table, and compares the detected value of at least one sensor for detecting the temperature and pressure in the tank with the combined value, The present invention relates to a method for monitoring a liquefied gas tank that determines whether a sensor is normal or abnormal.

  The present invention also relates to a method for monitoring a liquefied gas tank in which the liquid level in the tank is calculated from the valve opening degree of the valve provided in the supply system, the outside air temperature, and the supply pressure of the liquefied gas, and the outside air temperature and the liquefied gas. This relates to a monitoring method for a liquefied gas tank in which the supply pressure and the supply flow rate to the tank are linked to form a data table, and the liquid level in the tank is calculated based on the data table, and when the sensor is determined to be normal. Is related to a monitoring method of a liquefied gas tank in which equipment is operated with a detection value of a sensor and the equipment is operated with a composite value when the sensor is determined to be abnormal.

  The present invention also provides at least one tank sensor of a liquid temperature detection sensor for detecting the liquid temperature in the tank and a tank pressure detection sensor for detecting the pressure in the tank, an outside air temperature detection sensor for detecting the outside air temperature, Corresponding to the detection value detected by the tank sensor based on the supply pressure detection sensor for detecting the supply pressure of the liquefied gas, the outside air temperature detected by the outside air temperature detection sensor, and the supply pressure detected by the supply pressure detection sensor The liquefied gas tank monitoring apparatus includes a control device that calculates a combined value to be calculated and compares the detected value with the combined value to determine whether the tank sensor is normal or abnormal.

  The present invention also includes a valve opening degree detection sensor for detecting a valve opening degree of a valve provided in the supply system, and the control device is configured to detect the outside air temperature, the supply pressure, and the valve opening degree detection sensor. The present invention relates to a monitoring device for a liquefied gas tank that calculates a composite value based on the obtained valve opening, and the control device relates to an outside air temperature / liquefied gas supply pressure that associates an outside air temperature, a liquefied gas supply pressure, and a liquefied gas supply amount. A storage unit for storing a liquid level conversion data table in which a data table, a liquid level in the tank and a liquid temperature in the tank or a pressure in the tank are associated, and the liquid level in the tank based on the outside air temperature / liquefied gas supply pressure data table And a liquefied gas tank monitoring device that calculates a composite value based on the calculated liquid level and the liquid level conversion data table, and further, the control device compares the detected value with the composite value. The tank Determine normal or abnormal Sa, in the case of normal output the detected values, in the case of abnormal those of the monitoring device of the liquefied gas tank and outputs the combined value.

  According to the present invention, at least one of the temperature and pressure in the tank is associated with the liquid level of the tank to form a data table, the liquid level of the tank is calculated from the outside air temperature and the supply pressure of the liquefied gas, and the calculated tank Based on the liquid level and the data table, a composite value is calculated for at least one of the temperature and pressure in the tank, and the detection value of at least one sensor for detecting the temperature and pressure in the tank is compared with the composite value. Since the normality of the sensor is determined, the normality of the sensor can be determined even when only a single sensor is provided, and the reliability of the sensor and the system can be improved.

  According to the present invention, when the sensor is determined to be normal, the facility is operated with the detected value of the sensor, and when the sensor is determined to be abnormal, the facility is operated with the composite value. Even if it is determined to be abnormal, it is not necessary to stop the operation of the facility, so that the operation efficiency of the facility can be improved.

  According to the present invention, at least one tank sensor of a liquid temperature detection sensor for detecting the liquid temperature in the tank and a tank pressure detection sensor for detecting the pressure in the tank, and an outside air temperature detection for detecting the outside air temperature. A detection value detected by the tank sensor based on a sensor, a supply pressure detection sensor for detecting a supply pressure of the liquefied gas, an outside air temperature detected by the outside air temperature detection sensor, and a supply pressure detected by the supply pressure detection sensor And a control device that judges the normality / abnormality of the tank sensor by comparing the detected value with the synthesized value, so that only a single sensor is provided for the tank. Even in this case, normality / abnormality of the sensor can be determined, and the reliability of the sensor and the system can be improved.

  Also, according to the present invention, the control device compares the detected value with the combined value to determine whether the tank sensor is normal or abnormal, and outputs a detected value when normal, and combines with the combined value when abnormal. Since the value is output, it is not necessary to stop the operation of the facility even if the tank sensor is determined to be abnormal, so that an excellent effect of improving the operation efficiency of the facility is exhibited.

  The present invention simulates a sensor using an algorithm for estimating a normal process value based on other peripheral information even in a single sensor system in a liquefied gas such as LNG. When the sensor indication value becomes abnormal, it is possible to determine whether the sensor itself is malfunctioning or the equipment (process) is abnormal, and even if it is determined that the sensor itself is malfunctioning, It is possible to continue operation as a process and improve operational efficiency.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  First, an outline of a monitoring apparatus for a liquefied gas tank according to the present invention will be described with reference to FIG.

  In FIG. 1, 1 is a liquefied gas supply source, 2 is a tank filled with liquefied gas, liquefied gas is supplied to the tank 2 via a liquefied gas supply line 3, and the liquefied gas supply line 3 has An electromagnetic valve 4 for stopping the supply of liquefied gas is provided.

  The outside temperature sensor 5 detects the outside temperature value and outputs the outside temperature value T0 as a signal, the supply pressure detection sensor 6 detects the supply pressure of the liquefied gas and outputs the supply pressure value P0 as a signal, the tank The liquid temperature detection sensor 7 detects the liquid temperature of the liquefied gas in 2 and outputs the liquid temperature value T1t as a signal. The tank pressure detection detects the tank pressure in the tank 2 and outputs the tank pressure value P1t as a signal. A sensor 8 and a valve opening detection sensor 9 that detects the valve opening of the electromagnetic valve 4 and outputs the valve opening SV as a signal are provided. The outside air temperature detection sensor 5, the supply pressure detection sensor 6, and the liquid The detection signals of the temperature detection sensor 7, the tank pressure detection sensor 8, and the valve opening detection sensor 9 are signal processing units 11 and 12 that perform signal processing such as amplification, A / D conversion, noise removal by a smoothing filter, and the like. , 13, 14 Output 15 to the output control unit 16 via a input from said input output control unit 16 to the arithmetic and control unit (CPU) 17.

  A storage unit 18 is connected to the calculation control unit 17, and a threshold value used by a program such as a calculation program and a determination program to be described later, and a first determination unit 26 and a fourth determination unit 34 to be described later. 19, an outside air temperature / liquefied gas supply pressure data table 21, a liquid level / temperature conversion data table 22, a liquid level / pressure conversion data table 23, and the like are stored. The arithmetic control unit 17 and the storage unit 18 constitute a control device 20 of a monitoring device for the liquefied gas tank.

  The outside air temperature / liquefied gas supply pressure data table 21 indicates how much liquefied gas supply amount is in the tank 2 at a certain outside air temperature and a certain supply pressure, that is, how fast the liquid level rises. It is made into data, and is obtained by actual measurement or experience. Further, the liquid level / temperature conversion data table 22 is obtained by converting the relationship between the liquid level and the liquid temperature in the tank 2, and the liquid level / pressure conversion data table 23 is stored in the tank 2. The relationship between the liquid level and the pressure in the tank 2 is converted into data, both of which are actually measured or empirically obtained.

  The arithmetic control unit 17 includes the outside temperature detection sensor 5, the supply pressure detection sensor 6, the liquid temperature detection sensor 7, the tank pressure detection sensor 8, a signal from the valve opening detection sensor 9, and the threshold value 19. Based on the outside air temperature / liquefied gas supply pressure data table 21, the liquid level / temperature conversion data table 22, and the liquid level / pressure conversion data table 23, the liquid temperature detection sensor 7 and the tank pressure detection sensor 8 are normal. Abnormality is determined and a normal / abnormal determination signal is output to the host system 24.

  Further, the arithmetic control unit 17 calculates the synthetic liquid temperature value T1s and the synthetic tank pressure value P1s based on detection signals from the outside temperature detection sensor 5, the supply pressure detection sensor 6, and the valve opening degree detection sensor 9. When the calculation is normal, based on the determination result of normality of the liquid temperature detection sensor 7 and the tank pressure detection sensor 8, the liquid temperature value T1t and the tank pressure value P1t are sent to the host system 24. If it is determined that there is an abnormality, the synthetic liquid temperature value T1s and the synthetic tank pressure value P1s are sent to the host system 24.

  The host system 24 controls the operation of equipment such as controlling the opening degree of the solenoid valve 4 based on the liquid temperature value T1t and the tank pressure value P1t, or the synthetic liquid temperature value T1s and the synthetic tank internal pressure value P1s. .

  FIG. 2 shows the flow of signal processing in the control device 20, and the operation will be described below with reference to FIG. The case where the atmosphere of the tank 2 is constant temperature and normal pressure and the tank 2 is filled with a low-temperature liquefied gas such as LNG, or the case where the tank 2 is supplied to supplement the decrease due to evaporation after filling will be described.

  First, the case where the soundness of the liquid temperature detection sensor 7 is determined will be described.

  The liquid temperature signal detected by the liquid temperature detection sensor 7 is subjected to necessary signal processing such as A / D conversion and noise removal by the signal processing unit 14, and then the arithmetic control is performed via the input / output control unit 16. Input to the unit 17.

  The liquid temperature value T1t thus input is subjected to a threshold check by the first determination unit 26. In the threshold value check, it is determined whether or not the liquid temperature value T1t is within the set temperature range. If it exceeds the set temperature range, it is determined that there is an abnormality. In the first determination unit 26, it is determined whether or not an abnormality is detected due to physical damage or the like of the liquid temperature detection sensor 7. The first determination result 41 of normality / abnormality in the first determination unit 26 is sent to the second determination unit 27, and the liquid temperature value T1t is transmitted to the third determination unit 28 and the switching unit via the first determination unit 26. 29.

  The outside air temperature value T 0 output from the outside air temperature detection sensor 5, the supply pressure value P 0 output from the supply pressure detection sensor 6, and the valve opening degree SV output from the valve opening degree detection sensor 9 are respectively the signals. Signal processing is performed by the processing units 11, 12, and 13, and the signal is input to the arithmetic control unit 17 via the input / output control unit 16.

  The arithmetic control unit 17 liquefies the tank 2 based on the outside air temperature value T 0 and the supply pressure value P 0 based on the relationship between the outside air temperature / liquefied gas supply pressure data table 21 stored in the storage unit 18. Obtain the rising speed of the gas level. The rising speed of the liquid level obtained from the outside air temperature / liquefied gas supply pressure data table 21 is when the opening degree of the electromagnetic valve 4 is 100%, and the valve opening degree SV signal from the valve opening degree detection sensor 9 is By multiplying, the liquid level rising speed in accordance with the actual supply state is inferred and further integrated by the calculator 31 to calculate the liquid level in the tank 2.

  A liquid temperature value is calculated based on the liquid level in the tank 2 calculated from the liquid level / temperature conversion data table 22, and the calculated liquid temperature value is converted by the dynamic characteristic correction unit 32 to move the liquid temperature detection sensor 7. The calculated liquid temperature value is corrected so as to match the characteristic, and the synthetic liquid temperature value T1s is sent from the dynamic characteristic correction unit 32 and input to the third determination unit 28.

  The third determination unit 28 compares the liquid temperature value T1t input through the first determination unit 26 with the synthetic liquid temperature value T1s, and if the deviation is within a predetermined range, for example, within several degrees, When the predetermined deviation is exceeded, it is determined that the detection value of the liquid temperature detection sensor 7 is abnormal. The second judgment result 42 of normality / abnormality in the third judgment unit 28 is sent to the second judgment unit 27, and the synthetic liquid temperature value T1s is sent to the switching unit 29 via the third judgment unit 28. Is done.

  Whether the liquid temperature detection sensor 7 is normal based on the first determination result 41 from the first determination unit 26 and the second determination result 42 from the third determination unit 28 from the second determination unit 27. A determination 43 is output. That is, if any one of the first determination result 41 and the second determination result 42 is determined to be abnormal, the determination 43 becomes abnormal, and the determination of the first determination result 41 and the second determination result 42 is not performed. When both are normal, the determination 43 becomes normal. The switching unit 29 switches the determination 43 as a switching signal. When the determination 43 is normal, the switching unit 29 outputs the liquid temperature value T1t to the host system 24. When the determination 43 is abnormal, the synthetic liquid temperature value is output. T1s is output to the host system 24.

  The host system 24 determines the soundness of the liquid temperature detection sensor 7 based on the determination 43, or displays normality / abnormality on a display device or the like. The equipment is operated based on the liquid temperature value T1t output from the switching unit 29 or the synthetic liquid temperature value T1s.

  Next, a case where the soundness of the tank pressure detection sensor 8 is determined will be described.

  Determination of the soundness of the tank pressure detection sensor 8 is performed in the same manner as the determination of the liquid temperature detection sensor 7.

  The pressure signal in the tank 2 detected by the tank pressure detection sensor 8 is subjected to necessary signal processing such as A / D conversion and noise removal by the signal processing unit 15 and then via the input / output control unit 16. To the arithmetic control unit 17.

  The inputted tank pressure value P1t is subjected to a threshold check by the fourth determination unit 34. In the threshold value check, it is determined whether or not the tank pressure value P1t is within the set pressure range, and if it exceeds the set pressure range, it is determined that there is an abnormality. In the fourth determination unit 34, it is determined whether or not an abnormality is detected due to physical damage or the like of the tank pressure detection sensor 8. The third determination result 45 of normality / abnormality in the fourth determination unit 34 is sent to the fifth determination unit 35, and the tank pressure value P1t is transmitted to the sixth determination unit 36 and the switching unit via the fourth determination unit 34. 37.

  Based on the liquid level in the tank 2 integrated and calculated by the calculator 31 and the liquid level / pressure conversion data table 23, a tank pressure value based on the liquid level in the tank 2 is calculated, and the calculated tank The calculated tank pressure value is corrected by the dynamic characteristic correction unit 38 so that the pressure value matches the dynamic characteristic of the tank pressure detection sensor 8. The dynamic characteristic correction unit 38 sends a combined tank pressure value P1s and inputs it to the sixth determination unit 36.

  The sixth determination unit 36 compares the tank pressure value P1t input through the fourth determination unit 34 with the combined tank pressure value P1s, and the deviation between the two is within a predetermined range, for example, 0.05 MPa. If it exists, it is determined to be normal, and if the predetermined deviation is exceeded, it is determined that the detection value of the tank pressure detection sensor 8 is abnormal. The fourth judgment result 46 of normality / abnormality in the sixth judgment unit 36 is sent to the fifth judgment unit 35, and the combined tank pressure value P1s is sent to the switching unit 37 via the sixth judgment unit 36. Sent out.

  Whether or not the tank pressure detection sensor 8 is normal based on the third determination result 45 from the fourth determination unit 34 and the fourth determination result 46 from the sixth determination unit 36 from the fifth determination unit 35. A determination 47 is output. That is, if any one of the third determination result 45 and the fourth determination result 46 is determined to be abnormal, the determination 47 becomes abnormal, and the third determination result 45 and the fourth determination result 46 are not determined. When both are normal, the determination 47 becomes normal. The switching unit 37 switches the determination 47 as a switching signal. When the determination 47 is normal, the tank pressure value P1t is output to the host system 24. When the determination 47 is abnormal, the combined tank internal pressure is output. The value P1s is output to the host system 24.

  The host system 24 determines the soundness of the tank pressure detection sensor 8 based on the determination 47, or displays normality / abnormality on a display device or the like. The facility is operated based on the tank pressure value P1t output from the switching unit 37 or the combined tank pressure value P1s.

  As described above, the soundness of the liquid temperature detection sensor 7 and the tank pressure detection sensor 8 is determined based on sensors used in other parts, and further, the synthetic liquid is determined based on the sensors used in other parts. The temperature value T1s and the pressure value P1s in the combined tank are obtained, and even when the liquid temperature detection sensor 7 and the tank pressure detection sensor 8 are abnormal, the combined liquid temperature value T1s and the pressure value P1s in the combined tank are used. Therefore, the operation can be continued without stopping the facility immediately, so that the reliability of the sensor in the facility and the operability of the facility can be improved.

It is a schematic block diagram which shows embodiment of this invention. It is explanatory drawing explaining the effect | action of this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquefied gas supply source 2 Tank 3 Liquefied gas supply line 4 Solenoid valve 5 Outside air temperature detection sensor 6 Supply pressure detection sensor 7 Liquid temperature detection sensor 8 Tank pressure detection sensor 16 Input / output control part 17 Calculation control part 18 Storage part 19 Threshold 20 Control device 21 Outside air temperature / liquefied gas supply pressure data table 22 Liquid level / temperature conversion data table 23 Liquid level / pressure conversion data table 26 First determination unit 27 Second determination unit 28 Third determination unit 29 Switching unit 34 Fourth determination Part 35 fifth judgment part 36 sixth judgment part 37 switching part

Claims (8)

The liquid level of the liquefied gas in the tank with respect to the temperature and pressure in the tank filled with the liquefied gas at the required outside air temperature is measured or empirically obtained, and the liquid level of the liquefied gas and the temperature and pressure in the tank are and a data table in association with at least one preparative, outside air temperature, calculates the liquid level in the tank from the supply pressure of the liquefied gas, the temperature in the tank based on said the liquid level in the tank was the operational data table, the pressure at least A liquefied gas tank characterized in that a composite value is calculated for one, a detection value of at least one sensor for detecting temperature and pressure in the tank is compared with the composite value, and normality of the sensor is judged. Monitoring method.   2. The method for monitoring a liquefied gas tank according to claim 1, wherein the liquid level of the tank is calculated from a valve opening degree of a valve provided in the supply system, an outside air temperature, and a supply pressure of the liquefied gas.   The method for monitoring a liquefied gas tank according to claim 1 or 2, wherein the outside air temperature, the liquefied gas supply pressure, and the supply flow rate to the tank are associated to form a data table, and the liquid level in the tank is calculated based on the data table. .   The method for monitoring a liquefied gas tank according to claim 1, wherein when the sensor is determined to be normal, the facility is operated with a detection value of the sensor, and when the sensor is determined to be abnormal, the facility is operated with a composite value. Supply of liquefied gas, at least one tank sensor of a liquid temperature detection sensor that detects a liquid temperature in the tank and a tank pressure detection sensor that detects a pressure in the tank, an outside air temperature detection sensor that detects an outside air temperature, and a liquefied gas A supply pressure detection sensor for detecting pressure;
Measure the liquid level of the liquefied gas in the tank with respect to the temperature and pressure in the tank filled with the liquefied gas at the required outside air temperature or obtain it empirically, and the liquid level of the liquefied gas at the required outside air temperature and the tank A control device having a data table associating at least one of temperature and pressure therein,
The control device calculates the tank liquid level based on the outside air temperature detected by the outside air temperature detection sensor and the supply pressure detected by the supply pressure detection sensor ,
Based on the calculated liquid level of the tank and the data table, a composite value is calculated for at least one of temperature and pressure in the tank ,
A monitoring apparatus for a liquefied gas tank, comprising: a control device that compares a detection value detected by the tank sensor with the combined value to determine whether the tank sensor is normal or abnormal. A valve opening degree detection sensor for detecting the valve opening degree of a valve provided in the supply system is provided, and the control device detects the outside air temperature, the supply pressure, and the valve opening degree obtained by the valve opening degree detection sensor. The liquefied gas tank monitoring apparatus according to claim 5, wherein the liquid level of the tank is calculated based on the liquid level and the composite value is calculated based on the liquid level .   The control device includes an outside air temperature / liquefied gas supply pressure data table that associates an outside air temperature, a liquefied gas supply pressure, and a liquefied gas supply amount, a liquid level that associates a tank liquid level with a tank liquid temperature or a tank pressure. A storage unit for storing a conversion data table, calculating a liquid level in the tank based on the outside air temperature / liquefied gas supply pressure data table, and calculating a composite value based on the calculated liquid level and the liquid level conversion data table; The monitoring apparatus of the liquefied gas tank of Claim 5 which calculates.   The control device compares the detected value with the combined value to determine whether the tank sensor is normal or abnormal, outputs a detected value when normal, and outputs a combined value when abnormal. Liquefied gas tank monitoring device.

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