The water tank is a very common storage device used in the fluid industry. People need to calculate the amount of liquid storage, the control of inlet and outlet valves, the measurement of inflow and outflow, etc., and measure the specific water level, temperature, density, pressure (including pressure storage tank) and other parameters of the water tank through instruments. This is related to the storage tank Set-up related issues should follow the set-up principles and requirements of oil storage tanks. 1. General principles for the installation of water tank equipmentThe medium in the storage tank of the craft industry is generally a flammable hazardous substance. The setting of the instrument is related to the characteristics of the medium. The upper and low pressure storage tank should be equipped with a water level gauge, a thermometer, and a high-level alarm. The storage tank greater than or equal to 10,000 meters should be set high. The liquid level alarms and cooperates with the supply pipe control valve. The low-pressure storage tank should also be equipped with a pressure gauge.The high liquid level alarm value is the designed liquid storage capacity of the oil storage tank. Set the high alarm value: the maximum supply conversion height of the liquid storage tank for 10 to 15 minutes and the safety remaining volume of 0.3 meters.The low-level alarm needs to be met for 10 to 15 minutes to make time.The position where the thermometer is installed on the tank and the spherical tank should measure the liquid temperature at the lowest water level for easy observation and maintenance.Second, the specific requirements for the instrument settings of each tank1. Vault water tankSafe tanks generally require liquid level control, pressure control, liquid level linkage, and temperature alarm settings. Arch tanks usually use radar water level gauges, servo water level gauges, magnetostrictive water level gauges, radio frequency admittance water level gauges and other instruments to measure the water level.In addition, the arched water tank is mostly sealed with nitrogen to control the pressure separately.2. The dormitory tankThe dormitory barrel generally has liquid level control, liquid level linkage, pressure linkage, and sometimes it is necessary to set a temperature alarm. Commonly used water level gauges include buoys, magnetostrictive water level gauges, radio frequency admittance water level gauges, liquid level switches, and on-site water level gauges.3. Spherical tankAt room temperature, the gas storage tank (such as compressed air) usually needs to be set for pressure and temperature measurement. If necessary, it is necessary to set up a liquid level measurement at the bottom of the spherical tank for dehydration.The main body of the water tank in the liquefaction zone should be equipped with local and nuclear power station thermometers, which can measure the liquid temperature at the lowest water level for easy observation and maintenance.The liquefied spherical tank must be equipped with safety accessories such as safety valves, water level gauges, pressure gauges, and thermometers.The main body of the spherical tank should be equipped with on-site and remote pressure gauges, and a separate pressure limit alarm should be set. No other fittings or pipes can be connected between the pressure gauge and the spherical water tank. At the same time, it is necessary to ensure that the spherical water tank can measure the pressure on the air at the highest water level.The spherical water tank should be equipped with in-situ and nuclear power station water level gauges. Glass plate water level gauges should not be used. The water level gauges used should be safe and reliable to minimize the amount of perforation in the liquefaction tank.The spherical water tank should be equipped with high liquid level alarm and high liquid level linkage, and if necessary, a low liquid level alarm should be set.For liquefied petroleum balloon tanks used for water tank loading and unloading under intermittent operation, a high-water level automatic interlocking emergency shut-off supply device should be installed. For 1 trillion liquefied hydrocarbons or continuous operation of purification production equipment, the linkage requirements should be based on upstream and downstream processes The requirements of the production process are determined. The main material of the valve in the liquefied petroleum gas is carbon steel, which is resistant to low temperature and HS corrosion, such as the water tank material. The shut-off valve should use the shut-off valve, and the valve pocket pressure relief mechanism should be provided when selecting the gate valve and the ball valve. The design pressure of the valve must be above 2.5MPa.Emergency shut-off valves are also required for the import and export of liquefied petroleum balloon tanks, and the specific location should be near the spherical tank.The water tank in the liquefaction zone should be equipped with high and low liquid level alarms and high liquid level linkage to cut off the supply. High-level interlocking detection components should be installed independently. Ultrasonic, tuning fork, sub-ball or capacitive level switches can be used. Together with the high-level signals of remote water level gauges such as radar and servo, the supply can be cut off by “3 to 2″ linkage. . High-level interlock detection components must be able to be checked online. The setting height of the high liquid level alarm should be the designed storage liquid of the spherical tank. The setting height of the high level alarm cannot be greater than the height when the liquid volume reaches 90% of the calculated capacity of the spherical tank.According to the requirements of SIL, two sets of radar level gauges and one set of servo level gauges can be used for driving, and servo level gauges can be used for control or measurement. Sometimes, in order to reduce the start-up, etc., an external sticker is used instead of a set of radar water level gauges.4. Floating circulating water tankFloat tanks generally have liquid level control and liquid level linkage, and temperature alarms need to be set. Generally, radar water level gauges, servo water level gauges, magnetostrictive water level gauges, radio frequency admittance water level gauges and other instruments are used to measure the water level. These water level gauges can form a stable wave tube or a steel belt float water level gauge.The internal float tank sometimes needs to be sealed with nitrogen, and the pressure division control is often used.Rada-21 high frequency pulse radar level gauge5. Special water tank requirementsIf the liquefied hydrocarbons stored in the spherical oil storage tank contain HS, stress corrosion should be considered for the pressure element material. If the process requirements are met, the number of joints at the bottom of the spherical tank is reduced to a minimum.When storing unstable olefins, diolefins and other substances, measures should be taken to prevent the formation of peroxides and magnetic polymers.LNG or other low-temperature storage tanks should be equipped with a temperature monitoring system at the bottom of the water tank, which measures the temperature of the entire surface according to a predetermined pattern and monitors the performance of the bottom insulation layer and the basic heating system (if any) of the water tank.LNG or other low temperature media is connected to flanges, valves, seals or other unwelded joints. The leakage of the media may cause low temperature, so it should be designed to be suitable for or prevent low temperature.LNG storage tanks are usually double-walled, and there is a thermal insulation layer between the inner and outer water tanks.The LNG storage tank shall be equipped with two sets of independent level gauges. At the same time, the water level gauge should be able to adapt to changes in liquid density. Due to the unstable density of LNG, it is not appropriate to choose a differential pressure meter.The liquid ammonia storage tank should be equipped with at least two different types of liquid level detectors, and be equipped with high/low level alarm circuits and an interlock system between the liquid level and related process parameters when necessary.The design and installation of the water level gauge should adopt the configuration of the servo water level gauge, cut off the ball valve and calibration cavity, push the float into the calibration cavity when necessary for maintenance, cut off the ball valve, etc., and replace it so as not to affect the operation of the water tank. The storage tank must be equipped with two independent high level alarms, which can become part of the water level system. Setting the alarm point requires the staff to have enough time to end the oil flow so that it does not exceed the maximum allowable charging height. The alarm should be installed in a position where the charger can hear, and the alarm cannot be replaced by a higher water level.Except for the floating circuit storage tank, each storage tank should be equipped with a pressure gauge, and the pressure point should be higher than the highest level.A device with a vacuum fixture must have an instrument or interface to check the absolute pressure of the circular space.The storage tank should be equipped with a thermometer as a means to assist in temperature control or to check and calibrate the water level gauge when the storage tank surrenders.The foundation of low-temperature containers and equipment may be adversely affected by soil freezing or frost, so a temperature detection system is required.The instrument design of liquefaction, storage and gasification equipment should keep the system in a time-sensitive protection state when the instrument power supply or air supply fails, and allow the operator to take appropriate measures to restart or protect the system.
Various sealing, isolation, or other methods should prevent flammable liquids from flowing along pipelines, wiring, and cables.
Post time: 21-09-21