The factors discussed below influence the choice between trays & packings. As these are guidelines for selection of trays or packings for a particular service, it is recommended to analyze each design case on its own merit for selection.
| Sr.No. | System Favouring Tray Column | System Favouring Packed Column |
|---|---|---|
| 1 | Solid handling | Vacuum system |
| 2 | High liquid rate feed composition and temperature | Low pressure drop application, Revamps- The pressure drop reduction |
| 3 | Metals | Small diameter columns< 900 mm |
| 4 | Large diameter columns | Corrosive system Or Foaming |
Types of Tray
The particular tray selection and its design can materially affect the performance of a given distillation, absorption, or stripping system. Each tray should be designed so as to give as efficient a contact between the vapors and liquid as possible, within reasonable economic limits.
Sieve trays are perforated plates where the gas phase rises through the holes, and the liquid phase flows across the top of the tray. The interaction between the two phases promotes mass transfer.
Perforation Size: Typically ranges from 3mm to 12mm. The size affects the Vapour flow, liquid level & Mass transfer.
Open Area: Generally, between 6% to 15% of the total tray area. A higher open area can lead to weeping, while a lower open area can cause flooding.
Downcomer Area: This is the area where the liquid flows down to the tray below. It's typically 6% to 25% of the total tray area.
Material: Stainless steel, carbon steel, or other corrosion-resistant alloys, depending on the process fluid.
Floating valve trays are ideal for scenarios demanding higher turndown ratios. They offer superior efficiency across an extensive operational range compared to sieve trays due to their ability to control vapor flow.
S-Cube Mass Transfer Pvt. Ltd. offers a variety of floating valve trays, including:
A rectangular valve: with a unique design that prevents spinning and wearing
Conventional round valve trays: A cost-effective option that offers good performance.
All of our floating valve trays are made from high-quality materials and are designed to meet the specific needs of your application. We can also provide custom-designed trays to meet your exact requirements.
Benefits of Floating Valve Trays
Higher efficiency over a wider operating range
Increased turndown ratio
Reduced weeping
Longer life
Lower maintenance costs
These trays have risers or chimney-like structures (caps) that force the vapor to bubble through the liquid, enhancing contact and mass transfer.
Cap Diameter -
- i. Typically ranges from 25mm to 200mm.
Riser or Chimney Height -
- i. Usually 50mm to 100mm.
Slot Width -
- i. Around 10mm to 30mm,
- ii. Which determines the vapor velocity.
Material -
- i. Often made of stainless steel or other corrosion-resistant materials.
Spacing -
- i. The distance between the caps can vary,
- ii. But it's typically designed to optimize vapor-liquid contact.
Fixed valve trays are a type of distillation tray that combines the advantages of sieve trays and float valve trays. They have tapered, rectangular valves that are formed out of the tray deck and are oriented parallel to the liquid flow.
Advantages over traditional sieve trays:
Lower froth height and less entrainment: The lateral release of vapor through the valves helps reduce froth height and entrainment (carryover of liquid droplets with vapor), which prevents product loss and contamination.
Increased capacity and improved turndown: Fixed valve trays can handle higher vapor and liquid loads than sieve trays and have a wider turndown ratio (ratio of maximum to minimum operating rates), making them more versatile and adaptable.
Superior mechanical strength: The fixed valves are integrated into the tray deck, meaning there are no moving parts to wear out, resulting in a mechanically strong and durable design.
Excellent fouling resistance: Large valve openings facilitate easy cleaning, which helps prevent fouling (buildup of deposits) that can reduce efficiency and lead to operational problems.
S cube Fixed valve trays offer largest available fixed valve. Large lateral openings produce a vapor cleaning effect. Fixed valve trays have been successfully applied in a variety of fouling services such as Strippers, Waste water Towers. Fixed valve trays are well proven in various industrial applications ranging from low to high distillation.
Cartridge trays are typically used in narrow flanged columns where internal setups are impractical. These columns often have diameters between 300 and 800 mm (12" to 30"). For ease and quick installation, cartridge trays are assembled in groups. They can accommodate a variety of tray decks and downcomers.
FAQs
We offer several types including SCM Sieve Trays, SCM Floating Valve Trays, Bubble Cap Trays, SCM Fixed Valve Trays, and SCM Cartridge Trays, each designed for specific applications and operating conditions.
Sieve trays have simple perforations, while valve trays use movable valves that open and close based on vapor flow. Valve trays offer better turndown ratio and operating flexibility compared to sieve trays.
Floating valve trays offer excellent turndown capability, high efficiency, low pressure drop, self-cleaning action, and flexibility to handle varying flow rates effectively.
Bubble cap trays are ideal for applications requiring very low liquid rates, high turndown ratios, and situations where weeping must be completely prevented. They are particularly suitable for services with low liquid loads.
A cartridge tray is a modular, pre-assembled tray system that can be easily installed and removed from columns. It offers advantages in maintenance, installation speed, and flexibility for column modifications.
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