Because sulphuric acid has strong corrosiveness to metals, the safe storage of sulphuric acid storage tank is a very important link in the production, transportation and use process.
In order to ensure the safe operation of sulfuric acid storage tank facilities, correct anti-corrosion measures should be taken, such as reasonable design, correct material selection, strict management, etc.
Anti-corrosion design standards for sulphuric acid tanks:
According to the design criteria, (steel) sulfuric acid tanks can be divided into two types:
One is sulfuric acid tank of pressure vessel type, which includes vertical tank and horizontal tank. When nominal volume does not exceed 200 m_or design pressure is high, this type of tank is generally considered.
The other is large sulfuric acid tank at atmospheric pressure. When nominal volume is more than 200 m_and design pressure is not high, this type of tank is preferred.
Basic types of sulphuric acid tanks:
Because of the absence of high vapor pressure, sulfuric acid tanks do not need to use internal floating pans.
In order to isolate impurities such as air and rainwater, a fixed roof is needed to protect the medium inside the tank, usually a self-supporting fixed roof.
In addition, the reinforcement ribs and other supporting parts should be set on the outer wall of the tank roof, and the supporting parts should have sufficient corrosion margin; the parts below the liquid level should not have cracks and other defects.
For the sake of safety, it is generally not considered to set up an operation platform on the top of the tank. In order to facilitate operation and maintenance, an independent platform can be set up.
If the tank roof platform must be set up, the self-weight and additional loads of the top platform, pipe support and related equipment should be fully considered in the design of the tank roof.
Structural design of sulfuric acid anticorrosive tank:
Sulphuric acid storage tank should generally include at least 6 orifices: sulphuric acid inlet, sulphuric acid outlet, overflow orifice, vent (pressure valve orifice), top manhole and sweeping orifice.
In order to reduce leakage, the sulfuric acid inlet is usually set on the top of the tank, and the distance between the pipe mouth and the tank wall is at least 1200 mm. If the conditions are limited, the population can also be set near the top of the tank wall.
Sulfuric acid inlet should generally adopt the way of suction tube, that is to extend the nozzle below the liquid level.
Sulphuric acid export generally takes the way of suction tube, and most of them are detachable structure.
In order to facilitate disassembly, the diameter of the outer sleeve is usually more than twice the diameter of the sulfuric acid outlet pipe. In addition to the structure shown in the figure, the sulphuric acid outlet can also be designed as a flat nozzle.
In order to avoid sulfuric acid spillover caused by excessive liquid level, an overflow nozzle can be set on the upper part of the tank wall, and the nozzle of the overflow nozzle is even with the inner surface of the tank wall.
If no overflow outlet is set, the cut-off valve on the feeding line can be controlled by a high level instrument to achieve the goal.
In order to ensure good corrosion resistance of the tank, all welds under the liquid level should be fully penetrated butt joint structure, and local X-ray detection should be carried out.
For large storage tanks whose product of height and diameter exceeds a certain value, the longitudinal weld can be detected by 100% X-ray (at this time, the weld coefficient is 1.0).
Overlap welds can be used on tank roof, and all bottom welds should be full penetrating butt welds with cushion plates.