Tube‑in‑Tube Finned Heat Exchanger for Pharmaceutical Plant

Source of tail gas of pharmaceutical factory: secondary steam of Chinese medicine extraction and concentration, spray drying exhaust, granulation drying exhaust gas, solvent volatilization exhaust gas, boiler exhaust gas;

Characteristics of working conditions:

1. The exhaust gas contains water vapor, organic acids, organic solvents (ethanol, ethyl acetate, etc.), and powder dust, with strong dew point corrosion;

2. It is strictly prohibited for cooling water/hot water to leak into process waste gas, as any leakage may cause workshop pollution and product scrap;

3. Some exhaust gases are flammable and explosive, and it is not allowed for the medium to mix with each other;

4. Waste gas is prone to powdering and sticking, and requires maintenance and dust cleaning;

5. Waste heat recovery is used to preheat clean fresh air and process hot water, serving GMP production workshops.

Short plate of ordinary single tube fin heat exchanger

-The heat exchange tube directly contacts the exhaust gas, and once it corrodes and punctures, the water side medium directly enters the process exhaust gas, posing a significant GMP risk;

-Aluminum fins are not resistant to organic solvent steam corrosion and are prone to pulverization and debris entering the system.

Core advantage of casing fins (dual tube barrier)

-Inner pipe : circulating cold water/hot water/ethylene glycol;

-Ring gap (middle of inner and outer pipes) : spare leakage chamber;

-Welding stainless steel fins on the outer wall of the outer sleeve: The fins are horizontally flushed by exhaust gas to achieve heat transfer;

>Even if the inner tube corrodes and punctures, water will only enter the jacket layer and will not enter the process exhaust gas duct. The jacket layer can be equipped with a leak detection port to give an early alarm, prevent cross contamination, and meet the safety requirements of pharmaceutical factories.

Scenario 1: spray drying/granulation drying waste gas heat recovery (most commonly used)

-Operating conditions: Drying exhaust at 85-130 ℃, containing medicinal powder, water vapor, and a small amount of organic solvents;

-Process: High temperature exhaust gas flushes the stainless steel fins of the outer sleeve; Internal pipe circulating cold water absorbs heat;

-Produce hot water at 50-65 ℃ for preheating clean fresh air, process purified water, and workshop heating;

-Cooling of exhaust gas, partial condensation of water vapor, followed by exhaust gas treatment (spraying, activated carbon) at the rear end.

Scenario 2: Recovery of residual heat from secondary steam of traditional Chinese medicine extraction and concentration

-Secondary steam at 100-110 ℃, containing plant organic acids;

-Sleeve fins recover latent heat and heat to produce hot water; Double layered casing prevents circulating water from entering the steam system;

-The outer sleeve and stainless steel fins are resistant to organic acid dew point corrosion.

Scenario 3: Recovery of waste heat from exhaust gas in the boiler room of a pharmaceutical factory and preheating of clean fresh air

-Boiler flue gas at 140-220 ℃, recovering heat to produce hot water;

-Hot water is transported to the Hot Water Coil of the AHU air handling unit to preheat clean fresh air in winter;

>The exhaust side uses sleeve fins, while the clean air side still uses standard sanitary hot water coils, with the two separated.

Scenario 4: Pre cooling of process waste gas (cooling before entering RTO/spray tower)

-The high-temperature process exhaust gas is first pre cooled to 90-110 ℃ through casing fins to reduce the incineration and spray loads at the rear end;

-The sandwich leak detection structure prevents cooling water leakage from directly entering the exhaust gas pipeline, avoiding dilution of spray liquid and abnormal solvent concentration.