Alfa Laval Aalborg XW-TG Waste heat recovery economizer after diesel engine

The Aalborg XW-TG is a water tube, forced circulation exhaust

gas economizer designed to utilize thermal energy in diesel

engine exhaust gas. The standard Aalborg XW design has

been enhanced to more efficiently utilize the wasted energy

after large diesel engines with saved fuel consumption and

reduced CO2 emissions as a result.

Aalborg XW-TG generates superheated steam for power

generation by means of a steam turbine driven generator

(turbo generator).

The Aalborg XW-TG is based on and has the same charac

teristics as our well-known Aalborg XW which is a water tube,

forced circulation exhaust gas economizer with double gilled

tubes specially designed for heat recovery from diesel engine

exhaust gas.

When applied for large heat recovery rates, the heating surfaces

are required to be much increased in size and it is increasing

ly more important to focus on operation reliability to provide

full benefit of the relatively high investment.

For enhancement of an efficient, safe and reliable operation, the

Aalborg XW-TG is therefore among other things supplied with the

following equipment (advantageous for ordinary economizers as

well):

• Steam drum(s) for efficient separation of dry steam for

superheating

• High-efficient, electrical operated sootblowers using steam

or compressed air as blowing medium for on-load cleaning

• Fixed nozzle pipes for off-load water washing

• Extended monitoring equipment (e.g. exhaust gas pressure

drop/temperatures and fire detection)

• Dampers for by-passing of exhaust gas at low load operation

(and in case of emergency)

• Circulation pumps of canned motor type (with external

cooling) with flow monitoring system

• PLC based control system including online performance

monitoring and  help functions

The Aalborg XW-TG can be arranged in many different confi

gurations, e.g. for a single pressure or dual pressure system,

according to each individual requirement for steam and power

output.

We have developed and supplied the Turbo Compound System

in co-operation with Dresser Rand, Siemens AG and Wärtsilä

Corporation. Naturally, the system works equally well with other

diesel main engines, e.g. MAN engines. The Turbo Compound

System generates electric power equal or up to more than

11% of the main engine output on large container ships from

waste heat while at the same time reducing emission of harmful

exhaust gases like CO2. SOX and NOX into the environment.

We have achieved documented fuel savings and thereby

reduced CO2 emissions in double digit percentages.

Besides container ships, the Turbo Compound System can

also be applied with advantage to other ship types such as

VLCCs, bulk carriers, etc.