Storage Tanks are widely used in the chemical industry for the storage of raw materials, finished products and intermediate products, in order to ensure the safe production of devices, energy saving and emission reduction, improve the overall management level has an irreplaceable role, the national strategic reserves are also inseparable from the various types of storage tanks.
Industrial storage tanks are generally steel tanks, according to the characteristics of the storage medium and storage temperature, pressure and other parameters to choose carbon steel, low temperature steel, stainless steel and other materials, other materials such as glass fiber reinforced plastic, etc. due to fire, pressure resistance and other factors, will not be considered.
A, the classification of chemical storage tanks
Chemical storage tank, the tank to distinguish, then is able to be divided into metal, non-metallic and metal non-metallic composite of these three. Among them, the metal class of stainless steel and aluminum, etc., non-metallic class is ceramic and glass fiber reinforced plastic. And on the third, its typical representative is the steel lining raw materials.
Second, the safe operation of the tank and storage and transportation
Process industrial storage tanks are usually flammable, explosive, toxic media, so the safety of tank production is always the first, fire prevention, explosion-proof, overflow prevention, anti-evacuation, etc. need to have the appropriate measures.
For flammable and toxic media, detectors should be set up according to specifications and alarm signals should be introduced into the manned on-site control room or fire watch room.
The setting of the site detector should take into account the characteristics of the medium, environmental conditions, wind direction and other factors, while the limits of the detector itself should be considered.
In addition to the layout of the tank area according to the fire code, the fire protection requirements of the instrument itself should be considered, usually using flame retardant cable, metal channel plate laying or buried laying, the cable should be led from the top of the cofferdam to the outside of the cofferdam, or take effective fire blocking measures.
In order to avoid the expansion of the accident once the fire occurs, an emergency shut-off valve should be set in the import and export of the combustible medium storage tank, and should ensure that the valve is in a safe position when the power supply fails or the gas source fails, and an emergency shut-off button should be set at the entrance and exit of the cofferdam, the button is generally set as a tank group, i.e., once the fire occurs all the valves in and out of the storage tank in the cofferdam will be cut off, and when a pneumatic valve is used, it should Use PVC or nylon pipe to wrap around the valve body.
Emergency shut-off valves must be of fire resistant construction.
The overflow and evacuation prevention of the storage tank is achieved by setting suitable instrumentation, and the consequences of instrumentation failure or malfunction should be considered and addressed by measures such as two take one, two take two, or three take two, depending on the continuity and danger of the tank area operation.
Tank instruments should also take appropriate anti-static and lightning protection measures according to specifications.
Combustible liquid storage tank level, temperature, pressure and other measuring instruments, should use armored cable or wiring steel pipe wiring, cable sheath or wiring steel pipe and the tank should be made electrical connection.
Field installed instruments should meet the environmental requirements, field installed electronic instruments should meet at least IEC60529 and GB4208 standard IP65 protection level: non-electronic field instruments should meet at least IP55 protection level.
All electronically mounted field instruments should be classified according to the hazardous area and should be of a type that complies with IEC 60079 or GB 3836 and has a national explosion-proof certificate. It is worth noting that the low temperature of the environment may increase the explosive force, and the applicable temperature for explosion-proof certification in GB3836 is above -20°C. Therefore, when the ambient temperature is below -20°C corresponding measures should be taken or other explosion-proof forms should be used.
Third, the tank area and storage and transportation of common instruments
Storage tanks are commonly used in the fluid industry need to use storage equipment, the main measurement of its level, temperature, density and pressure (with pressure tanks) and other parameters, according to which the volume and mass storage of the stored liquid is calculated, as well as the import and export valve control, in and out of the flow of the necessary measurement.
Refrigeration of low temperature storage tanks is not discussed here.
Storage tanks are generally divided into intermediate tanks and trade tanks (raw materials, finished products) two categories.
Intermediate storage tanks only for the level, temperature and pressure (with pressure storage tanks) and other parameters to monitor, in order to prevent the tank from topping, vacuum and other accidents, do not need to handover metering; trade with the medium in the tank level, temperature, density, volume, quality must be monitored and measured, and high precision requirements. Different volumes and types of tanks, the performance characteristics of the level meter used are not the same, therefore, according to the needs of users and investment conditions, the reasonable choice of level meter, in order to achieve the most reasonable performance to price ratio.
In addition to meters for metering, the need for stability and reliability of other meters is higher than the need for accuracy.
In the instrument selection should be based on environmental conditions (temperature, humidity, altitude, marine climate, sand, etc.) tank form, tank maintenance and operation cycle, combined with the whole life cycle costs, choose the right instrument.
Fourth, chemical storage tanks of note
1. chemical storage tanks for maintenance and other operations, then should first cut off the electrical equipment related to the power supply, and then can be carried out. If necessary, the equipment should also be handled to account for the procedures.
2. In chemical storage tanks to carry out in-tank work, should have the appropriate work permit. If there is a long interruption, then it is necessary to deal with it from the beginning.
3. If the chemical storage tank storage is flammable, explosive or corrosive media, then the relevant rules should be strictly in accordance with the requirements to operate.
4. In the process of operation, the need to establish scaffolding, or lifting equipment, etc., then to ensure that it is strong and secure, and then to ensure that safe operation.
5. The closing of the manhole on the chemical storage tank should be carried out only after the guardian has signed the work permit in the tank.
6. In the tank work, outside the tank must be supervised, and choose a reliable contact method, so that people outside the tank can know the operating conditions in time. Once the emergency situation arises, immediately adopt useful methods.
Source: sage.com
Disclaimer: This article is a network reproduction, the copyright belongs to the original author. If there are any copyright issues, please contact us and we will remove the content at the first time.
October 18, 2022
