Evaporators

Products & Solutions

Evaporators:

CESCO proudly represents Alfa Laval inc., the industry leader in plate evaporator technology.

AlfaVap Plate Evaporator Technology (Alternating Gasketed & Welded Channels as Cassettes)

The unique AlfaVap design provides much higher thermal efficiency than traditional shell-and-tube evaporators and condensers. This means much less heat transfer area is needed to achieve any specific effect. AlfaVap units are therefore extremely cost-effective, especially when exotic materials such as SMO, titanium, nickel and Hastelloy(™) are required.

The compactness and versatility of the AlfaVap design means drastic reductions in transportation, erection and installation costs compared to traditional solutions.

AlfaVap 700

Turnkey AlfaVap Plants

The plate construction of AlfaVap means the heat transfer surfaces are easy to get at for inspection and any mechanical cleaning. Removing the tightening bolts and rolling back the pressure plate are all it takes.

The special corrugated patterns of the heat transfer plates create a high degree of turbulence over the entire surface of each plate. This helps prevent fouling and makes chemical cleaning extremely effective. The low hold-up volume of an AlfaVap unit also means only very small amounts of cleaning chemicals are needed.

The design of the AlfaVap makes it easy to adjust evaporation and condensation capacity to meet changing needs, simply by adding or removing plates to the existing frame. This is a major advantage in relation to shell-and-tube units, where the capacity cannot be changed once it has been installed.

AlfaVap is tailor-made for evaporation, with two small inlet feed connections located centrally in the bottom of the frame plate, and large outlets for the vapor and concentrate at the top.

There is one large inlet connection for the heating steam, and two small outlets for the condensate. AlfaVap uses the cassette concept with the plates welded in pairs. The heating steam is condensed in the welded channels while the evaporated product passes through the gasketed channels.

Brazed Plate Evaporator Technology (Copper-Brazed Stainless Plates)

Brazed plate heat exchangers are widely used in refrigeration plants. Units in the Alfa Laval AC series of copper-brazed heat exchangers can be used as evaporators for dry expansion and cooling water.

Dry expansion - Evaporation of the liquid phase takes place inside the channels. Some degree of superheating is always required – hence the process being called "dry expansion".

Evaporator flow principle - The channels formed between the corrugated plates and corners are arranged so that the two media flow through alternate channels, always in opposite directions (counter current flow). The two phase refrigerant (vapor + liquid) enters the bottom left of the exchanger with a vapor quality depending on the operating condition of the plant. Evaporation of the liquid phase takes place inside the channels and some degrees of superheat are always requested, which is the reason why the process is called "dry expansion". In the enclosed evaporator picture the dark and light blue arrows show the location of the refrigerant connections. The water (brine) to be cooled flows counter current in the opposite channel; the dark and light red arrows show the location of the water (brine) connections.

Alfa Laval has a wide range of single and double circuit brazed plate evaporators. Here is a range of units showing capacities for R22 in air conditioning duties:

AlfaDisc All-welded Plate Evaporator

AlfaDisc is a compact, welded heat exchanger for refrigeration applications including two-phase and single-phase liquid/gas cooling. It is manufactured for a wide range of duties making it applicable for low and high temperatures (over 200°C/400°F), as well as high pressures (100b/ASME 680 psi). These characteristics make the AlfaDisc a perfect fit with natural refrigerants like ammonia and carbon dioxide. AlfaDisc provides the thermal efficiency and the compactness of a plate-and-frame heat exchanger while handling temperatures and pressures otherwise requiring shell-and-tube units. It has a high tolerance for thermal expansion compared to other welded technologies. The plate and the shell modules can be constructed of different materials selected to withstand corrosive fluids and to satisfy demands for process fluids in high and low temperature applications.

Removable Bundle is Available

How it works - AlfaDisc is constructed of a shell and a plate pack with alternating channels for pure co-current or counter-current flows. The refrigerant typically condenses or evaporates on the shell side where the two-phase flow is assisted by flow restrictors. On the plate side, water or bines are normally pumped through the welded channels. In some applications, for example cascade systems, phase change can occur on both the plate side and the shell side.

Three standard plate sizes are currently available, providing from 235 to 1,733 sq ft of area:

There are several spots for an AlfaDisc in an industrial refrigeration system, including as a flooded evaporator for natural refrigerants such as ammonia and carbon dioxide, or HFC's: