Author | Fan Yongfeng Chen Hongpei Yu Miao
Fan Yongfeng | Zhongke Synthetic Oil Engineering Co., Ltd. Deputy Chief Engineer, Professor-level Senior Engineer
Chen Hongpei | Zhongke Synthetic Oil Engineering Co., Ltd. is deputy chief engineer and senior engineer of instrumentation
Yu Miao | Zhongke Synthetic Oil Engineering Co., Ltd. is the person in charge of instrumentation and engineer
The capacity is not the same, the storage tank measurement instrument configuration is not the same, many people do not know in line with the industry standard of the measurement level and non-metering level storage tank how to configure, this article for the storage tank different instrument configuration proposed a program, for your reference.
>> Illustrated examples are only for the terms of the standards and documents mentioned in the diagrams and tables, excluding standards and document requirements not mentioned.
Scenario 1:
Schematic diagram of metering level atmospheric and low pressure storage tank instrument configuration
Scenario two:
Schematic diagram of non-metered atmospheric and low pressure storage tank instrument configuration
Scenario three:
Schematic diagram of metering-grade pressure storage tank instrument configuration
Scenario FOUR:
Schematic diagram of non-metered pressure storage tank instrument configuration
Overall:
According to SH/T 3184-2017 "Code for the Design of Automation Systems for Petrochemical Tank Farms", the configuration scheme is as follows:
Excerpts from the terms of the relevant standard documents:
SH/T 3007-2014 Code for The Design of Tank Farms for Petrochemical Storage and Transportation Systems
5 Atmospheric and low pressure storage tank areas
5.4.1 Storage tanks with a capacity greater than 100 m3 shall be equipped with a remote instrument for continuous measurement of liquid levels.
5.4.3 Storage tanks for storing Class I and Class II toxic liquids, tanks of Class A B and Class B A combustible liquids with a capacity greater than or equal to 3000 m³, and other liquid storage tanks with a capacity greater than or equal to 10000 m³ shall be equipped with high level alarms and interlocks, and high level alarms shall interlock the control valves of the inlet pipelines of the storage tanks.
5.4.4 The device raw material storage tank should be set with a low and low level alarm, and the low and low liquid level alarm should be interlocked to stop the pump.
5.4.5 The liquid level measuring instrument of the high and low level alarm signal of the storage tank shall adopt a separate liquid level continuous measurement instrument or liquid level switch, and the alarm signal shall be transmitted to the automatic control system.
5.4.6 The storage tank shall be equipped with a temperature measuring instrument. The thermometer on the floating top tank and the inner floating top tank should be installed at 700mm~1000mm above the bottom of the tank. The thermometer on the fixed top tank should be installed at 700mm~1500mm above the bottom of the tank. When there is a heater in the tank, the upper limit should be taken, and when there is no heater, the lower limit should be removed.
5.4.7 The low-pressure storage tank shall be equipped with a pressure measurement in-situ indicator instrument and a pressure remote instrument. Pressure-in-place indicator instruments and pressure remote meters must not share a single opening. The pressure gauge should be installed in a position that ensures that the pressure of the gas phase can be measured at the highest level and is easy to observe and maintain.
5.4.10 When the instrument or instrument element is installed on the top of the tank, it should be arranged near the ladder platform of the tank roof.
5.4.11 The liquid level, temperature and pressure measurement signals of the storage tank shall be transmitted to the control room for centralized display.
6 Pressure storage tank area
6.3.1 The pressure storage tank shall be equipped with a pressure in-place indication instrument and a pressure remote instrument. Pressure-in-place indicators and pressure remote meters must not share a single opening.
6.3.2 Pressure storage tank level measurement should be provided with a set of remote instruments and a set of in-situ indication instruments, and the local indication instrument should not use a glass plate level gauge.
6.3.3 The level measurement remote instrument shall be set with high and low liquid level alarms. The set height of the high level alarm should be the design of the storage tank to store the high level; the set height of the low level alarm should meet the requirements that the pump will not cavitate within 10min to 15 minutes from the alarm.
6.3.4 The pressure storage tank shall be equipped with another set of liquid level measuring instruments or liquid level switches dedicated to the high level alarm and interlocking to cut off the valve of the feed pipeline of the storage tank. The set height of the high level alarm should not be greater than the height at which the liquid phase volume reaches 90% of the calculated volume of the tank.
6.3.5 Pressure storage tanks shall be equipped with temperature measuring instruments.
6.3.6 Pressure, level and temperature measurement signals of the pressure storage tank shall be transmitted to the control room for centralized display.
6.3.7 The installation position of the thermometer on the pressure storage tank shall ensure that the temperature of the liquid phase can be measured at the lowest level and easy to observe and maintain.
6.3.9 The instrument or instrument component of the tank roof should be arranged near the ladder platform of the tank roof.
SH/T 3184-2017 "Code for the Design of Automation Systems for Petrochemical Tank Farms"
4 Tank metering and measurement solutions
4.1 Tank metering or non-metered classification
4.1.1 The design of the storage tank instrument shall be based on the needs of the storage and transportation process, and the instrument measurement scheme shall be set up according to the measurement level or non-metering level.
4.2 Instrument measurement scheme for storage tanks
4.2.1 Metering-grade atmospheric and low-pressure storage tanks
4.2.1.1 The storage tank with a volume greater than 100m³ should be set up with a continuous level measurement instrument at the top of the tank, and the storage tank with a volume of not less than 1×105m³ should be set up with 2 sets, and the liquid level continuous measurement instrument should be equipped with a tankside indicator to display the liquid level, and a high and low level alarm should be set in the control system.
4.2.1.2 According to the process requirements in the control system should be set high, low low level alarm and interlock, the signal used in the measuring instrument should be set separately, should be used continuous measurement instrument, can also use the liquid level switch; should be set high level interlocking to close the tank inlet pipeline switch valve, low low level interlocking pump and close the outlet pipe switch valve control scheme, alarm and interlocking should be realized in the control system.
4.2.1.3 When the storage tank needs to measure the standard volume and standard density of oil products, a multi-point thermal resistance thermometer or a single-point thermal resistance thermometer should be set up to measure and calculate the average temperature of the oil in the tank, and the output signal is directly connected to the continuous measurement instrument of the liquid level of the storage tank.
4.2.1.4 The metering level storage tank should be provided with a multi-point thermal resistance thermometer, installed on the top of the tank, should be in accordance with the effective height of the tank within the range of every 3m and other intervals of the average arrangement to determine the number of temperature measurement points, the minimum number of points of the multi-point temperature detection element should comply with the provisions of Table 4.2.1.4; when the storage tank volume is less than 159m³ or the tank height is less than 3m, a single-point thermal resistance thermometer should be set up and installed in the lower part of the tank.
4.2.1.5 Thermal resistance thermometers can be set individually or integrated with oil-water boundary measurements.
4.2.1.6 It is advisable to set up a bimetall thermometer below the minimum liquid level in the lower part of the storage tank, and should comply with SH/T 3007-2014 "Petrochemical Storage and Transportation System Tank Area Design Code No. 5.4.6 "The thermometer on the floating roof tank and the inner floating roof tank should be installed at 700mm~1000mm above the bottom of the tank. The thermometer on the fixed top tank should be installed at 700mm ~ 1500mm above the bottom of the tank" provisions.
4.2.1.7 The storage tank containing water in the medium and layered shall be provided with an oil-water boundary measuring instrument, which can be used as a separate measuring instrument, or can be integrated with the thermal resistance thermometer, and the signal is directly connected to the storage tank level continuous measurement instrument to calculate the actual liquid level.
4.2.1.8 The storage tank shall be provided with a pressure or differential pressure transmitter for density calculation, the source port shall be set below the minimum liquid level of normal operation, above the oil-water boundary, and the output signal shall be connected to the continuous measurement instrument of the tank level or the data management unit of the storage tank.
4.2.1.9 When measuring the bottom pressure of the tank by means of static pressure to calculate the liquid level, the density shall be measured by means of a pressure (or differential pressure) transmitter.
4.2.1.10 Low-pressure storage tanks and storage tanks that require inert gases such as nitrogen shall be set up at the top of the tank to measure the pressure and set up a pressure gauge to measure the pressure in situ.
4.2.1.11 Pressure transmitters and pressure gauges must not share the same source interface.
4.2.1.12 When inert gases such as nitrogen are required for sealing of fixed top tanks and internal floating top tanks, nitrogen sealing valves or pressure interval control shall be provided.
4.2.1.13 Nitrogen sealing valve nitrogen inlet pipeline shall be provided with a pressure gauge.
4.2.1.14 The tank top instrument shall be installed near the tank roof platform, the tank wall instrument shall be installed where the escalator is reached, and all instruments shall be easy to observe and maintain.
4.2.2 Non-metered atmospheric and low pressure storage tanks
4.2.2.1 The storage tank with a volume greater than 100m³ should be set up with a continuous liquid level measurement instrument at the top of the tank, and the storage tank with a volume of not less than 1×105m³ should be set up with 2 sets, and the liquid level continuous measurement instrument should be equipped with a tankside indicator to display the liquid level, and a high and low level alarm should be set in the control system.
4.2.2.2 According to the process requirements in the control system should be set high, low low level alarm and interlock, the measurement instrument used in the signal should be set separately, should be used continuous measurement instrument, can also use the liquid level switch; should be set high level interlocking tank inlet pipe switch valve, low low level interlocking stop pump and close the outlet pipe switch valve control scheme, alarm and interlocking should be realized in the control system.
4.2.2.3 Non-metered tank temperature measurement is only used for process monitoring, it is advisable to set up a single-point thermal resistance with an on-site temperature transmitter, and the output signal is connected to the tank farm control system.
4.2.2.4 It is advisable to set up a bimetall thermometer below the minimum liquid level in the lower part of the storage tank, and shall comply with ARTICLE 5.4.6 of SH/T 3007-2014 "The thermometer on the tank tank and the inner floating roof tank should be installed at 700mm~1000mm above the bottom of the tank." The thermometer on the fixed top tank should be installed at the bottom of the tank at 700mm~ 1500mm. ".
4.2.2.5 Low-pressure storage tanks and storage tanks that require inert gases such as nitrogen shall be equipped with a pressure transmitter to measure the pressure at the top of the tank, and a pressure gauge shall be set up to measure the pressure in situ.
4.2.2.6 Pressure transmitters and pressure gauges must not share the same source interface.
4.2.2.7 When inert gases such as nitrogen are required for sealing of fixed top tanks and internal floating top tanks, nitrogen sealing valves or pressure slitting control shall be provided.
4.2.2.8 Nitrogen sealing valve nitrogen inlet pipeline shall be provided with a pressure gauge.
4.2.2.9 The tank top instrument should be installed near the tank roof platform, the tank wall instrument should be installed in the escalator, and all instruments should be easy to observe and maintain.
4.2.3 Gauge-grade pressure storage tanks
4.2.3.1 Two sets of continuous level measuring instruments equipped with tankside indicators shall be set up at the top of the tank, one of which is used to set high and low level alarms in the control system.
4.2.3.2 According to the process requirements in the control system should be set high liquid level alarm and interlocking closed storage tank feed pipeline switch valve control scheme, the signal using the above another set of liquid level continuous measurement instrument; when the third set of liquid level instrument is needed, it is advisable to use continuous measurement instrument, can also use the liquid level switch.
4.2.3.3 When it is necessary to measure the standard volume and standard density of oil products, a multi-point thermal resistance thermometer or a single-point thermal resistance thermometer should be set up to measure and calculate the average temperature of the oil in the tank, and the output signal is directly connected to the continuous measurement instrument of the liquid level of the storage tank.
4.2.3.4 The metering level storage tank should be provided with a multi-point thermal resistance thermometer, installed on the top of the tank, should be arranged in accordance with the average arrangement of each 3m equal spacing within the effective height range of the storage tank to determine the number of temperature measurement points, the minimum number of points of the multi-point temperature detection element should comply with the provisions of Table 4.2.1.4 of this specification; when the storage tank volume is less than 159m³ or the tank height is less than 3m, a single-point thermal resistance thermometer should be set up and installed in the lower part of the tank.
4.2.3.5 Thermal resistance thermometers can be set individually or integrated with oil-water boundary measurements.
4.2.3.6 A bimetallic thermometer shall be provided below the minimum level in the lower part of the tank.
4.2.3.7 The storage tank containing water and layered by the medium shall be provided with an oil-water boundary measuring instrument, which can be used as a separate measuring instrument or integrated with a thermal resistance thermometer, and the signal is directly connected to the storage tank level continuous measurement instrument to calculate the actual liquid level.
4.2.3.8 The storage tank may be set up as needed for differential pressure or pressure transmitter or other forms of density meter for density calculation, the source port is set below the minimum liquid level of normal operation, above the oil-water boundary, and the output signal is connected to the tank liquid level continuous measurement instrument or storage tank data management unit.
4.2.3.9 Two pressure transmitters shall be set up at the top of the tank to measure the pressure, and a pressure alarm shall be set in the control system, and the pressure gauge shall be set to measure the pressure in situ.
4.2.3.10 Pressure transmitters and pressure gauges must not share the same source interface.
4.2.3.11 When the ball tank needs to be sealed with inert gases such as nitrogen, pressure interval control shall be provided.
4.2.3.12 If an in-situ level indicator is required, a glass plate level gauge should not be used.
4.2.3.13 The tank roof instrument shall be installed near the tank roof platform, the tank wall instrument shall be installed in the escalator, and all instruments shall be easy to observe and maintain.
4.2.4 Non-metered pressure storage tanks
4.2.4.1 Two sets of continuous level measuring instruments equipped with tankside indicators shall be set up at the top of the tank, one of which is used to set high and low level alarms in the control system.
4.2.4.2 According to the process requirements in the control system should be set high level alarm and interlocking closed storage tank feed pipeline switch valve control scheme, the signal using the above other set of liquid level continuous measurement instrument; when the third set of liquid level instrument is required, it is advisable to use continuous measurement instrument, can also use the liquid level switch.
4.2.4.3 Non-metered storage tank temperature measurement is only used for process monitoring, it is advisable to set up a single point thermal resistance with on-site temperature transmitter, and the output signal is directly connected to the tank farm control system.
4.2.4.4 A bimetallic thermometer shall be placed below the minimum level in the lower part of the tank.
4.2.4.5 Two pressure transmitters shall be set up at the top of the tank to measure the pressure, and a pressure alarm shall be set in the control system, and a pressure gauge shall be set to measure the pressure in situ.
4.2.4.6 Pressure transmitters and gauges must not share the same source interface.
4.2.4.7 When the ball tank needs to be sealed with inert gases such as nitrogen, pressure interval control shall be provided.
4.2.4.8 If an in-situ level indicator is required, a glass plate level gauge shall not be used.
4.2.4.9 The tank top instrument should be installed near the tank roof platform, the tank wall instrument should be installed in the escalator, and all instruments should be easy to observe and maintain.
SH 3136-2003 "Design Code for Petrochemical Liquefied Hydrocarbon Spherical Storage Tanks"
5 Gauges
Liquefied hydrocarbon spherical storage tanks should be monitored, controlled and managed according to the requirements of the process, using advanced technology and reliable performance of metering, data acquisition, monitoring, alarm system. The selected instrument should be suitable for the design pressure and design temperature of the liquefied hydrocarbon spherical storage tank, and ensure that the instrument components in contact with the medium should have corrosion resistance when the storage medium is corrosive. When the instrument or instrument element must be installed on the top of the tank, it should be arranged near the ladder platform of the tank top.
5.1 Temperature
The liquefied hydrocarbon spherical storage tank body should be equipped with in-situ and remote thermometers, and the well should ensure that the temperature of the liquid phase can be measured at the lowest level and is easy to observe and maintain.
5.2 Pressure
The upper part of the liquefied hydrocarbon spherical storage tank body should be provided with in-situ and remote pressure gauges, and a separate pressure high limit alarm should be set. No fittings or nodules for other purposes shall be connected between the pressure gauge and the spherical tank. The position of the pressure gauge on the liquefied hydrocarbon spherical storage tank should ensure that the pressure of the gas phase can be measured at the highest level and is easy to observe and maintain.
5.3 Liquid level
5.3.1 Liquefied hydrocarbon spherical storage tanks should be equipped with in-situ and remote level gauges, but glass plate level gauges should not be selected. The level gauge used should be safe, reliable and minimize the number of holes in liquefied hydrocarbon spherical storage tanks.
5.3.2 Liquefied hydrocarbon spherical storage tanks shall be equipped with high level transmitters and high level linkages. If necessary, a low level alarm should be added.
5.3.3 For the liquefied petroleum gas spherical storage tank loaded and unloaded by the tank truck under intermittent operation, an automatic interlocking device with a high liquid level shall be set up to urgently cut off the feeding device. For spherical storage tanks in which a one-component liquefied hydrocarbon or refining production unit operates continuously, the interlocking requirements should be determined according to the requirements of their upstream and downstream process production processes.
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