What are the applications of acid-base storage tanks in the chemical industry
Acid alkali storage tanks are key equipment used in the chemical industry to store acidic or alkaline media, and their design needs to take into account corrosion resistance, safety, and media characteristics. The following will explain from the aspects of application scenarios, typical media, structural characteristics, and selection points:
Acid alkali storage tanks are key equipment used in the chemical industry to store acidic or alkaline media, and their design needs to take into account corrosion resistance, safety, and media characteristics. The following will explain from the aspects of application scenarios, typical media, structural characteristics, and selection points:
1、 Application scenarios and typical media
1. Storage of chemical raw materials
Acidic medium:
Sulfuric acid (H ? SO ?): used in the production of fertilizers, pesticides, and dyes. Storage tanks should be made of carbon steel (dilute sulfuric acid at room temperature) or stainless steel (concentrated sulfuric acid), lined with acid resistant rubber or fiberglass reinforced plastic (FRP) to prevent corrosion.
Hydrochloric acid (HCl): commonly used for metal surface treatment and organic synthesis. Storage tanks are often made of polypropylene (PP), polyethylene (PE), or fiberglass to avoid the reaction of metal materials with hydrochloric acid and the production of hydrogen gas.
Nitric acid (HNO ∝): As a strong oxidant, it is used in the production of pharmaceutical intermediates and requires 304/316 stainless steel storage tanks (nitric acid has a protective effect on the passivation film of stainless steel).
Alkaline medium:
Sodium hydroxide (NaOH): commonly known as caustic soda, used in papermaking, textiles, and water treatment. The storage tank can be made of carbon steel (alkali resistant at room temperature) or PE material, and insulation layer should be installed to prevent crystallization.
Ammonia water (NH ∝? H ? O): used in fertilizer and denitrification processes, the storage tank needs to be sealed to prevent volatilization, and the material is mostly stainless steel or rubber lined carbon steel to avoid ammonia gas leakage.
2. Storage of intermediate products and finished products
Chemical synthesis process: For example, in the production of adipic acid, nitric acid reaction solution is stored, and in the production of polyester, terephthalic acid (PTA) slurry is stored. The storage tank needs to have stirring function (to prevent precipitation) and temperature control (to maintain reaction conditions).
Pre storage of finished products before packaging: Organic acids such as citric acid and acetic acid are stored in food grade stainless steel (316L) tanks that comply with food safety standards (such as FDA certification).
3. Wastewater treatment and environmental protection engineering
Acid alkali neutralization process: storing sulfuric acid and sodium hydroxide required for wastewater neutralization, the storage tank is often equipped with a metering pump for automatic addition, and the material is PE or FRP (resistant to wastewater impurities corrosion).
Waste gas treatment: If ammonia water (alkaline) or dilute sulfuric acid (acidic) is stored in the desulfurization and denitrification process, the storage tank should be equipped with a breathing valve and waste gas absorption device to prevent volatilization pollution.
2、 Key structural design and safety configuration
1. Anti corrosion design
Inner lining protection: For example, carbon steel tanks are lined with polytetrafluoroethylene (PTFE) for storing hydrofluoric acid (HF), which can corrode glass and metal. Only fluoroplastics such as PTFE can withstand it.
Coating treatment: Spray epoxy zinc rich paint (alkali resistant) or phenolic resin (acid resistant) on the inner wall of the storage tank to extend its service life.
2. Security Attachment Configuration
Breather valve: to prevent pressure rise caused by the evaporation of the medium inside the tank (such as acid resistant breather valves required for hydrochloric acid storage tanks).
Emergency relief device: such as a bursting disc, which automatically ruptures and releases pressure when the pressure inside the tank exceeds the design value to avoid explosion.
Liquid level gauge and thermometer: Real time monitoring of medium inventory and temperature to prevent medium evaporation caused by overloading or high temperature (such as ammonia water storage tanks requiring temperature control ≤ 30 ℃).
Grounding device: When storing flammable media (such as a mixture of ethyl acetate and sulfuric acid), anti-static grounding is required to prevent electrostatic sparks from igniting.
3. Special function design
Mixing device: when storing acid-base slurry easy to precipitate (such as calcium hydroxide lotion), a side entry mixer shall be equipped to prevent solids from settling and blocking the outlet.
Insulation/cooling jacket: If concentrated sulfuric acid releases heat when diluted, the storage tank needs to be equipped with a cooling water jacket to control the temperature ≤ 60 ℃ and avoid acid mist evaporation.
3、 Industry standards and selection points
1. Follow the standards
Domestic standards: GB 150 "Pressure Vessels" (applicable to storage tanks with a design pressure ≥ 0.1MPa), HG/T 20640 "Plastic Equipment" (PE/PP storage tanks).
International standards: ASME BPVC VIII (American Pressure Vessel Standard), EN 13445 (European Union Tank Code), export equipment must comply with corresponding standards.
2. Key factors for selection
Medium characteristics: concentration, temperature, corrosiveness (for example, 316 stainless steel is required for 98% concentrated sulfuric acid, while carbon steel and lining rubber can be used for 70% sulfuric acid).
Storage capacity and pressure: atmospheric pressure storage tank (pressure ≤ 0.02MPa) vs low-pressure storage tank (0.02~0.1MPa), the latter needs to be designed according to the pressure vessel.
Environmental requirements: Outdoor storage tanks need to consider sun protection (installing sunshades), anti freezing (insulation layer+electric heat tracing), and salt spray corrosion resistance (stainless steel material is preferred) in coastal areas.
4、 Typical Industry Application Cases
Petrochemical industry: Acid alkali washing solution is stored in the atmospheric and vacuum distillation unit for crude oil desalination and dehydration. The storage tank is made of 316L stainless steel and equipped with an online pH monitoring system.
Coal chemical industry: In the coal to hydrogen process, concentrated ammonia water (25% concentration) is stored in tanks lined with carbon steel and nitrile rubber, and an ammonia recovery device is installed.
New energy materials: Hydrofluoric acid (40% concentration) is stored in the production of lithium battery electrolytes, using PTFE material storage tanks with fully enclosed design to prevent fluoride leakage.
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