Category: Industry Trends

The Alfa Laval Aalborg XS-7V is a robust smoke-tube economizer.

Easy to install, operate and maintain, it reduces the use of the

fired marine boiler by recovering heat energy that otherwise

would be lost through the exhaust gas. The Aalborg XS-7V is

similar to the Aalborg XS-2V, but it shares a steam space with

the fired boiler instead of having its own steam space.

Its proven design includes a dual-inlet option, which creates

high installation flexibility.

Easy steam production with dual-inlet flexibility

• Simple and reliable design based on 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

• Dual-inlet option allowing connection of two engines to one

economizer

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-2V or XS-7V 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

• Simple and reliable design based on 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

• Dual-inlet option allowing connection of two engines

to one economizer

Working principle

The Aalborg XS-2V and XS-7V are installed after a vessel’s

main or auxiliary engines. When the exhaust gas passes over

the economizer’s heating surface, the waste heat energy in

the gas is absorbed for the production of steam. Dry running

is possible in the event of an emergency.

The two models differ in how produced steam is handled:

• The Aalborg XS-2V is a full exhaust gas boiler with its own

steam space, which can operate independently from the

fired boiler.

• The Aalborg XS-7V is designed for forced circulation

and is used in connection with one or more fired boilers,

which act as the steam space.

Waste heat recovery economizers for marine engines

The Alfa Laval Aalborg XS-2V and XS-7V are robust smoke-tube

economizers. Easy to install, operate and maintain, they reduce

the use of the fired boiler by recovering heat energy that

otherwise would be lost through the engine exhaust gas.

This ensures a rapid return on investment. The Aalborg XS-2V

is equipped with its own steam space, which makes it a

complete exhaust gas boiler. The Aalborg XS-7V shares a steam

space with the fired boiler. The proven design of both

economizers includes a dual-inlet option, which creates high

installation flexibility.

Design

Built for simplicity and reliability, the Aalborg XS-2V and

XS-7V have a vertical, all-welded design with straight smoke

tubes. The option of dual inlets allows one economizer to

serve two engines, with half the tubes dedicated to one

engine and half dedicated to the other. This can reduce

installation costs and complexity.

The smoke-tube design is easy to clean and maintain,

especially as the high gas velocity through the economizer

minimizes fouling. If needed, individual smoke tubes can also

be repaired or replaced.

Working principle

The Aalborg Micro is installed after a vessel’s auxiliary engine

(or small main engine). It has a short start-up time of just

two minutes. When the exhaust gas passes over its heating

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

production of hot water or steam. An internal damper, which

allows up to 80% of the exhaust gas to bypass the heating

surface, keeps back pressure within safe limits.

The Aalborg Micro is not designed with its own steam space.

It is used in connection with one or more fired boilers, which

act as the steam/water space. Forced-circulation pumps pro

vide the Aalborg Micro with water at saturation temperature

from the fired boiler(s).

In the Aalborg Micro, heat from the engine exhaust gas is

transferred to the water side by convection. The generated

steam/water mixture is then discharged into the steam space

of the fired boiler(s), where the heavier water particles sepa

rate from the steam.

Benefits

• Extremely compact, plug-and-play design for easy retrofit

• Easy improvement of Carbon Intensity Indicator (CII)

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

25% fuel savings on the oil-fired boiler

• Reduced wear and maintenance on the fired boiler

• Internal damper for dynamic management of

pressure drop

Design

Built for lasting performance, the Aalborg Micro has a durable

construction where the coaxial tubes of the heating surface

are arranged within a vertical cylindrical shell plate. The

heating surface is designed for easy maintenance, with an

integrated soot blower that supports the daily cleaning of

the coiled fin tubes.

In operation, a control damper forces the exhaust gas flow

from the engine to pass between the tube coils. This damper

also acts as an internal bypass, allowing back pressure to be

regulated without the need for an external bypass.

The Alfa Laval Aalborg Micro is a uniquely compact

water-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 engine exhaust gas. This ensures

a rapid return on investment.

Despite its minimal footprint, height and weight,

the Aalborg Micro has an extended heating surface

created by coiled fin tubes. Even more efficient than

smoke-tube economizers, it provides an ideal retro

fit solution where no other economizer will fit.

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 en

ergy as possible. This is true for auxiliary engines as well as

main engines.

Steam produced with the Aalborg Micro 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 Aalborg Micro can

be used to generate electricity, for example by means of

Organic Rankine Cycle (ORC) technology.

Technical data

Gas Turbines fired with different fuels such as:

• Natural gas

• Diesel oill

Heating media:

• Hot water

• water-steam

• Superheated steam

• Thermal oil

• TEG or equal

Design options:

• Dry run or non-dry run

• With or without integral bypass and diverter damper

• External and Internal insulation

• Fixed or removable tube bundle

Materials:

• Tubes in carbon steel, alloy steel or stainless steel

• Casing and ducts in carbon or corten steel

Alfa Laval’s Waste Heat Recovery Unit (WHRU)

optimized for recovering waste heat after gas turbines.

Application

The waste heat recovery unit recovers thermal energy in

the waste heat from the gas turbine exhaust gas,

enabling generation of hot water, water-steam or

superheated steam. The WHRU is also capable of heating

up thermal oil and TEG, and can be designed to fit

individual customer needs and optimum performance.

Customer benefits

• Customized design

• Global service network

• Large installed base

• Large manufacturing capabilities

• WHRU incl. extended scope

Applications

• FPSO

• Process industry

• District heating

• Power generation

Standard scope of supply

• WHR-unit

• Insulation & cladding

• Ducts

• Stack

• Silencer

• Expansion joints

• Diverter

• Control system

• Instrumentation

• Deaerator/feed water tank

• Feed water treatment system (incl. chemical dosing unit)

• Bypass – external or internal byppass

• Documentation  (relevant manuals, certificates etc.)

Exhaust gas economizers capture waste heat energy from engines,

gas turbines and more, enabling its reuse for steam production or

other processes.This saves fuel, which provides rapid payback and

helps reduce CO2 and other emissions. It also reduces the running

hours of the fired boiler/heater, which lowers maintenance costs.

Our Alfa Laval Aalborg portfolio includes a wide range of economizers

for industrial and marine use, as well as standalone exhaust gas

boilers with integrated steam drums.

We have effective waste heat recovery solutions to match a wide

variety of needs. Our Alfa Laval Aalborg exhaust gas economizers

and exhaust gas boilers combine exceptional thermal efficiency

with proven reliability.

Benefits of Alfa Laval Aalborg exhaust gas economizers

• Significantly reduced emissions of CO2 and other greenhouse

gases

• Short payback time through fuel savings due to reduced reliance

on combustion

• Compact design ensured by optimized heating surfaces with high

thermal efficiency

• Innovative options for easy installation and integration – even in

retrofit situations

• Specific engineering to match each engine’s data and operating

conditions