Category: Alfa Laval

Alfa Laval decanter centrifuges support solid-liquid separation in a seamless, continuous process.

Stand out from the competition with high-performance separation that delivers clarified or

extracted products of exceptional quality and superior commercial value. Recover valuable raw

materials, reduce energy consumption, and lower your environmental footprint and waste

management costs—always backed by service expertise for optimal performance and long-term

reliability of your decanter separator.

Experience maximum solid-liquid separation efficiency

• High-performance separation, resulting in high-value products and low waste management costs

• Lower energy consumption and carbon footprint

• Minimal maintenance costs thanks to continuous operation, high-grade machine materials,

smart design and well-thought preventive services

• Low capital cost/capacity ratio

• Wide-ranging feed variations and controllable performance

A comprehensive range of decanters for water, food and energy industries

Solid-liquid separation is a common manufacturing process in countless industries, and Alfa Laval

has over 60 years of experience using decanter centrifuges to meet this requirement.

Their operation makes use of centrifugal force – the effect can be up to 4000 times greater

compared to using gravitational forces.

Alfa Laval uses high-grade stainless steel for all parts in contact with the solid-liquid separation

process to prevent corrosion. High-stress rotating components are machined from high-strength

centrifugally cast stainless steel – ensuring uniform, flaw-free castings and weld-free components

for maximum strength, reliability, and long service life. Wear-prone areas, such as the feed zone,

solids discharge output zone, bowl, and scroll, are protected by abrasion-resistant materials tailored

to each industrial process. Continual refinement of the seal technology used in Alfa Laval decanter

separators is ensured by our technological resources for superior performance.

Tailored configurations

The Aalborg XWi boiler drum can be integrated with electrical

heating elements to utilize shore power connection for steam

generation while on port. The heating surface configuration is

flexible. The energy efficiency of the system can be increased

by adding tube section for feed water preheating and/or

superheating as well as hot water generation. The design of

the heating surface can be tailored to the actual engine and

operating conditions, maintaining sufficient exhaust gas velocity

for the best self-cleaning effects within the design limits.

How it works

Natural circulation refers to the ability of fluid in a system to

circulate by means of gravity and density differences. In the

Aalborg XWi, circulation begins naturally when the engine starts

and ends naturally when the engine stops. Water remains inside

the heating surface tubes, which prevents the risk of a soot fire,

and energy loss is minimized because there is no unnecessary

circulation during standstill.

Because water only circulates through the Aalborg XWi when the

engine is running, no heat is lost to the cold air that flows through

the boiler when the engine is stopped. This means less use of the

fired boiler, with lower fuel costs and emissions as a result.

When the circulation is stopped, water fills the boiler tubes. This

minimizes the risk for soot fires, which can occur with forced

circulation. In forced circulation, typical system arrangement and

sudden changes in engine load often lead to problems in water

circulation, such as pump cavitation, which can cause a soot fire

within the system.

Design

The Aalborg XWi has the same heat transfer features as a

traditional exhaust gas boiler with forced circulation, but its

special design eliminates safety risks, heat losses, continuous

maintenance needs and pump operating costs.

The heating surface of the Aalborg XWi is made up of gilled

water tubes as standard, with a construction that minimizes soot

build-up. In addition, the system can be equipped with optimized

steam sootblowers. Design pressure and boiler capacity can be

optimized according to specific needs.

The boiler can be designed with its own integrated steam

drum, or with a separate steam drum. There are no operational

connections to fired boilers, which means more redundancy, but

still considerably less piping. The boiler’s own dedicated water

circulation system eliminates the risk of water hammering.

Key Benefits

• Simple, reliable operation based on natural circulation,

without pumps or rotating components

• Maximized safety, minimized risk of soot fires

• Minimal heat losses

• No circulation pumps to operate or maintain – avoid pump

electricity consumption and continuous maintenance costs

• Reduced total installation and material costs

• Clear responsibility limit – including piping between the boiler

and the drum

• Increased system redundancy

• Potential integration of electrical steam generation while

engine is not running

• Modular design enabling tailored configurations, including

selectable multi-stage heating solutions

Introduction

The Alfa Laval Aalborg XWi is an exhaust gas steam boiler with

an integrated natural circulation system. Natural circulation

uses physical phenomena to drive the water through the boiler

unit, which removes the need for circulation pumps.

The Aalborg XWi offers considerable savings and optimal

operational safety, as confirmed by the positive feedback from

customers.

The Aalborg XWi offers savings in waste heat recovery systems

on vessels that have four-stroke engines and are frequently

put in to harbour, such as cruise vessels and passenger ferries.

The Aalborg XWi eliminates all typical problems associated

with forced circulation systems, such as cavitation, water

hammering, and operation and main tenance losses.

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.