Alfa Laval Aalborg XS-TC7A Waste heat recovery economizer for marine auxiliary engines

The Alfa Laval Aalborg XS-TC7A is an efficient

smoke-tube economizer. Easy to install, operate

and maintain, it reduces the use of the fired boiler

by recovering heat energy that otherwise would

be lost through the exhaust gas. This ensures

a rapid return on investment.

Thanks to the helix shape of its smoke tubes,

the Aalborg XS-TC7A offers a large heat transfer

area within a compact footprint. This enhances

its performance and makes it the smallest smoke

tube economizer on the market.

Application

Only a portion of the fuel energy released by marine engines

actually goes to propulsion. A large amount of it escapes as

heat, and it makes sense to reclaim as much of this energy

as possible. This is true not only for main engines, but for

auxiliary engines as well.

Steam produced with the Aalborg XS-TC7A can support or

fulfil steam needs in port, but it can also serve other functions.

For vessels whose long-stroke main engines produce

cooler exhaust, it can provide a needed steam boost during

a voyage. If there is no steam shortage while sailing, the

additional steam produced with the economizer can be used

to generate electricity, for example by means of Organic

Rankine Cycle (ORC) technology.

Benefits

• Compact and efficient design based on helix smoke tubes

• Easy improvement of Carbon Intensity Indicator (CII)

• Short payback time (typically 1–2 years) through up to

25% fuel savings on the fired boiler

• Reduced wear and maintenance on the fired boiler

• Long service life thanks to self-cleaning Turbo Clean

technology

Working principle

The Aalborg XS-TC7A is installed after a vessel’s auxiliary

engine. When the exhaust gas passes over its heat¬ing

surface, the waste heat energy in the gas is absorbed for the

production of steam. The economizer can be adapted for dry

running in the event of an emergency.

The Aalborg XS-TC7A features an optimized convection part

that augments heat transfer by increasing turbulence at the

exhaust gas boundary layer. This contributes to increased

steam production while reducing the economizer’s weight

and footprint.

The economizer is designed for forced circulation and is used

in connection with one or more fired boilers, which act as the

steam space.

Design

Built for simplicity and reliability, the Aalborg XS-TC7A has a

vertical, all-welded design with helix smoke tubes. The helix

design of the tubes greatly increases the available heat trans

fer area, which makes this the smallest smoke-tube econo

mizer on the market. Together with the optimized convection

section, it ensures a high ratio of output to weight.

The helix tubes and the economizer’s self-cleaning Turbo

Clean technology both reduce soot build-up, which makes

XS-TC7A easy to clean and maintain. If needed, individual

smoke tubes can also be repaired or replaced.