Acid Detergent Disassembly And Cleaning Service For Plate Heat Exchangers

Service Overview

Service Process and Technical Key Points

1. Preliminary Inspection and Assessment
   • Check the operating parameters of the heat exchanger (such as temperature difference between inlet and outlet, pressure drop) to determine the degree and type of scaling.
   • Record the number of plates, arrangement sequence, and gasket status before disassembly to avoid errors during reassembly.
2. Design of Chemical Cleaning Plan
   • Selection of acid detergents: Choose suitable acidic agents based on the composition of the scale (such as calcium carbonate, calcium sulfate, metal oxides, etc.). Common agents include:
     • Citric acid: Suitable for light to moderate scale, with low corrosion and high safety.
     • Oxalic acid/hydrochloric acid: Aimed at severe rust scale or sulfate scale, with high cleaning efficiency, but the concentration (usually 1%-5%) and cleaning time (≤2 hours) must be strictly controlled to avoid corrosion of plates (e.g., 316L stainless steel).
     • Composite acid cleaners: Added with corrosion inhibitors and surfactants to enhance cleaning effects and protect metal surfaces.
   • Cleaning process:
     • Circulating cleaning: Pump the acid detergent into the heat exchanger and circulate it at a flow rate of 0.3-0.5 m/s for 30-60 minutes to dissolve the scale layer.
     • Soaking cleaning: For stubborn scaling, soak for 15-30 minutes before circulation to enhance the dissolution effect.
3. Disassembly and Physical Cleaning
   • Remove the clamping bolts in sequence, separate the plate pack, inspect whether the gaskets are aged or damaged, and replace them in a timely manner.
   • Rinse the surface of the plates with a high-pressure water gun (pressure ≤10 MPa) to flush away residual scale, and use a soft brush to remove deposits in hard-to-reach areas. Avoid using hard tools like steel wool to scratch the plates.
4. Neutralization and Rinsing
   • After cleaning, circulate a 1%-2% sodium carbonate or sodium hydroxide solution for neutralization to prevent residual acid from corroding the plates.
   • Rinse repeatedly with deionized water or soft water until the pH value of the outlet water is close to 7 and the conductivity is ≤10 μS/cm.
5. Assembly and Debugging
   • Assemble the plates in the original order, ensure the gaskets are installed in place, tighten the clamping bolts evenly in a diagonal sequence, and control the torque within the manufacturer's specified range (e.g., 15-25 N·m).
   • Conduct a hydraulic pressure test (1.25 times the working pressure, hold for 30 minutes), check for any leaks, resume equipment operation, and record the parameters after cleaning.

     Advantages	Detailed Description
     High-efficiency descaling	Acid detergents dissolve over 95% of inorganic scale, and heat transfer efficiency can be improved by 30%-50% after cleaning.
     Customized solutions	Adjust the agent formula according to the plate material (stainless steel, titanium alloy, etc.) and scaling type to avoid material damage.
     Safety and environmental protection	Use low-toxic corrosion-inhibiting acid agents and equip with wastewater treatment devices. The cleaning wastewater can meet discharge standards after neutralization.
     Prolong equipment life	Removing scale can reduce the operating pressure of the equipment, reduce the risk of plate corrosion and perforation, and extend the replacement cycle by 1-2 years.

• Scaling in plate heat exchangers of heating systems leading to unmet room temperature standards;
• Blocked flow channels in heat exchangers supporting chemical reactors due to material crystallization;
• Protein and oil deposits in heat exchangers of the food and beverage industry affecting sterilization effects.

Precautions

1. Safety protection: Operators must wear acid-resistant gloves and goggles. Prepare neutralizers and flushing water sources on-site to prevent acid agents from contacting the skin or splashing into the eyes.
2. Material compatibility: Do not use hydrochloric acid to clean aluminum plates. Special weak acid cleaners should be selected for titanium plates to avoid crevice corrosion.
3. Cycle recommendation: Depending on water quality and working conditions, cleaning is recommended every 6-12 months. For working conditions with high water hardness (>300 mg/L) or easy scaling, the cycle can be shortened to 3-6 months.