Category: Alfa Laval

Benefits of natural circulation

• Lower capital expenditure (CAPEX)

• Lower operational expenditure (OPEX)

• Maximized uptime and operational safety

• Lower parasitic electricity consumption for steam generation

• Easy boiler water chemistry control. Tolerant to varying

make-up water quality and no need for condensate

polishing

• Lower weight and less crowded layout due to simpler

circulation line piping when compared to conventional

forced-circulation systems

Extended scope

Alfa Laval’s supply comprises a high number of in-house

products beyond the HRSGs themselves, such as plate heat

ex-changers, steam drums, feed-water deaerator tanks,

condensate tanks, blow-down tanks and solutions for boiler water

chemistry management. The remaining equipment, such as

pumps, instrumentation and valves, are sourced from reputable

makers who are suitable for the offshore environment and your

specification levels. The wide internal scope, combined with Alfa

Laval steam system expertise, ensures professional customer

support – all the way from concept development to ser-vice

requirements over the solution lifetime.

For more information on Alfa Laval’s overall steam system  offering

for the offshore market, please see our “Offshore steam systems

and services” brochure.

Natural-circulation HRSGs

Alfa Laval’s HRSG design offers the possibility of natural

circulation evaporators, which combine maximum uptime with

reduced capital and operational expenditure. Natural-circulation

evaporators operate without circulation water pumps, which are

known to be high-maintenance items due to harsh operational

conditions and fluctuations involved at sea. The circulation in

the evaporators is induced naturally by the density difference

between vapour and liquid, providing trouble-free operation with

minimum O&M involvement throughout HRSG lifetime.

Alfa Laval has extensive experience with natural-circulation

HRSGs in both land and marine environments. Our first land-

based installation was in the 1990s, and marine installation

in the 2000s. Since then, we have gained a market-leading

position in natural-circulation HRSGs for marine segments.

Cruise ships and icebreakers are among the more challenging

environments for HRSGs and the associated steam system, due

to highly intermittent operating profiles combined with a dynamic

seafaring environment. The fact that Alfa Laval dominates in

these applications is evidence of our expertise in HRSGs and

natural circulation.

If you specify, Alfa Laval can also deliver pump-driven HRSG

systems.

Benefits of choosing Alfa Laval Aalborg Hukka-8 HRSGs

• Improved efficiency of electricity production (up to 20%

increase in fuel-to-power efficiency)

• Over 30% reduced gas turbine fuel consumption

• Smaller carbon footprint

• Support from Alfa Laval steam system experts

• Possibility of seamless integration with Alfa Laval steam

system equipment, designed and manufactured specifically

for marine and offshore  applications

• Availability of Alfa Laval’s global service network

Typical technical data (per HRSG)

• Gas turbine output: Up to ~55 MWe

•  Steam flow: Up to 80 t/h

•  Steam pressure: Up to 80 bar(g)

•  Flue gas flow: Up to 150 kg/s

•  Steam production: From saturated steam to 550°C super

heated steam

Alfa Laval Aalborg natural-circulation Hukka-8 HRSG Modules

with extended-scope delivery

Introduction

Alfa Laval’s highly efficient and robust water-tube Aalborg

Hukka-8 Heat Recovery Steam Generators (HRSGs) and related

steam system equipment are always tailored to your specific

requirements. Our entire supply is designed and engineered to

last for the lifetime of the production unit, utilizing proprietary Alfa

Laval control and monitoring systems combined with first-class

manufacturing standards and surface treatment.

Alfa Laval offshore waste heat recovery and steam system

products are also available as modules for streamlined installation

in the yard. Our modularized supply ensures the heat recovery and

steam system components work together in an optimal way, and

it reduces the number of external interfaces. This secures safe and

efficient operation on an overall system level. On your end, it also

simplifies the development and project execution of equipment

related to the steam system, as the major part steam system

responsibility is handed to us.

Deriving from our decades of experience in making offshore boiler

modules and onshore combined cycle heat recovery plants,

Alfa Laval steam system components are both fit for application

and suitable for the harsh offshore operating environment. This is

supported by wide reference base of projects with different marine

and offshore classification requirements. Thanks to our wide

experience base, you can rest assured on regulatory compliance

and operational excellence of Alfa Laval HRSG systems, all the

way from manufacturing to complete service life of installation.

Aalborg H/HW boiler is designed for waste heat recovery after gas or diesel engines.

Both boilers have a simple and very reliable construction.

Horizontal or vertical installation with excellent vibration resistance

• Stable output due to relatively large water volume

• Excellent match for HFO heating or applications with low to moderate steam demands

• Integrated exhaust gas bypass system for capacity modulation

• Valves and instrumentation with a selectable range of automation

• Suitability for district heating via hot water

Design data

• Engine output:No limits, depending on engine

• Engine fuel type: Light oil, liquid biofuel, heavy fuel oil, natural gas

• Exhaust gas inlet temperature:< 530 °C

• Exhaust gas flow: No limits

• Typical operating pressure:< 20 bar(g)

• Steam temperature: Saturated

• Typical pinch point: > 20 ºC

How it works

Aalborg H/HW boilers are available with vertical or horizontal layouts.

The Aalborg H, which is used for steam generation, has an integrated steam space and

employs natural circulation. The Aalborg HW, which is used in hot water applications,

has flow-optimizing baffle plates and employs forced circulation.

Both models have a simple and reliable construction comprised of bare smoke tubes,

which are welded to tube plates at both ends of the shell.

Design data

• Engine output:No limits, depending on engine

• Engine fuel type: Light oil, liquid biofuel, heavy fuel oil, natural gas

• Exhaust gas inlet temperature:< 530 °C

• Exhaust gas flow: No limits

• Typical operating pressure:< 20 bar(g)

• Steam temperature: Saturated

• Typical pinch point: > 20 ºC

Unique boiler construction

A unique supporting arrangement without endplates, enhanced by computerised

analyses ensures a vibration and thermal stress-free boiler structure sustaining

even the most demanding operational conditions of engine-based heat recovery

applications.

Reliable natural circulation

As a standard for steam applications, Alfa Laval Aalborg offers reliable natural

circulation solutions without the need of circulation pumps providing the following

advantages:

• Reliability

• Minimised risk of soot fires

• Less power consumption

• Cost effectiveness

• Fast site installation

• Reduced foundation work and minimized piping and cabling

• Small footprint

Conventional forced circulation boilers are also available.

Easy to clean

The tube arrangement of the Aalborg AV-6N heating surface ensures easy

maintenance and service. Aalborg AV-6N boilers can be cleaned during operation

reducing the need for engine shut-down. In addition to standard high-efficient

steam soot blowers, an air-type can also be applied.

Hot-water heating for free

The Aalborg AV-6H exhaust gas boiler is a water tube boiler for heat recovery,

typically after gas engine. The boiler comes in a horisontal layout and compact

workshop assembled module. It is easy and fast to install while allowing maximized

access for convenient maintenance and service.

• High-efficient counterflow design for heating of hot water

• Proven design to ensure effective and fast cleaning of condensed lube oil residuals

(in gas engine application)

• Compact and flexible layout with integrated walkable service area

• Low operational weight

• Minimized gas pockets

Alfa Laval offers reliable natural circulation solutions as a

standard for steam applications, eliminating the need for

circulation pumps and providing several advantages. These

include enhanced reliability, minimized risk of soot fires, reduced

power consumption, cost effectiveness, fast site installation,

reduced foundation work, minimized piping and cabling, and

a small footprint. Additionally, conventional forced circulation

boilers are also available.

Hot-water heating for free

Waste heat can also be recovered for use in hot water systems,

typically downstream of gas engines. The boiler module is

available in either vertical or horizontal configurations and

is delivered as a compact, pre-assembled unit. This design

ensures quick and straightforward installation, while providing

optimal access for maintenance and servicing.

• High-efficient counterflow design for heating of hot water

• Proven design to ensure effective and fast cleaning of

condensed lube oil residuals (in gas engine application)

• Compact and flexible layout

• Low operational weight

• Minimized gas pockets

Easy to clean

The tube arrangement of the Aalborg AV-6N heating surface

ensures easy maintenance and service. Aalborg AV-6N boilers

can be cleaned during operation reducing the need for engine

shut-down. In addition to standard high-efficient steam soot

blowers, an air-type can also be applied.

Design data

• Engine output: No limit, depending on engine

• Engine fuel type: Light oil, liquid biofuel, heavy fuel oil,

natural gas

• Typical exhaust gas flow: 5–60 kg/s

• Exhaust gas temp.: Standard up to 610 ºC

• Operating steam/water pressure: Typically 5-30 bar(g),

max. 65 bar(g)

• Steam/water temperature: Standard up to 450 ºC

• Natural circulation as standard – forced on special demand

• Pinch point: Typical 10 – 20 ºC (min. 5 ºC, limited by

feasibility only)

Unique boiler construction

A unique supporting arrangement without endplates, enhanced

by computerised analyses ensures a vibration and thermal

stress-free boiler structure sustaining even the most demanding

operational conditions of engine-based heat recovery

applications.

Reliable natural circulation

Alfa Laval offers reliable natural circulation solutions as a

standard for steam applications, eliminating the need for

circulation pumps and providing several advantages. These

include enhanced reliability, minimized risk of soot fires, reduced

power consumption, cost effectiveness, fast site installation,

reduced foundation work, minimized piping and cabling, and

a small footprint. Additionally, conventional forced circulation

boilers are also available.

Easy to clean

The tube arrangement of the Aalborg AV-6N heating surface

ensures easy maintenance and service. Aalborg AV-6N boilers

can be cleaned during operation reducing the need for engine

shut-down. In addition to standard high-efficient steam soot

blowers, an air-type can also be applied.