www.howden.com

Pre-engineered industrial Package HeatersAir preheaters configured for today’s operating conditions

Howden regenerative air heaters use a slowly rotating rotor loaded with heating elements that transfer energy from the hot gas to cold air.

By removing heat from the flue gases leaving the furnace, which in turn reduces the heat lost up to the chimney the heat exchanger preheats the air which goes directly to the burners. This significantly increases the overall thermal efficiency of the boiler.

Regenerative air heaters offer distinct advantages over tubular air heaters. These include:

More compact design

Lower pressure drop

Lower weight

Fouling does not affect heat transfer

Improved cleanability

Greater performance flexibility

Eliminates cold corner problems

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Advances in element design and enamelling have dramatically raised maintenance and thermal efficiency and cleanability, improved seals have increased system integrity, and parameter-based computerised design has vastly reduced engineering lead times. These are major steps that make Howden regenerative heaters the most cost effective choice for new plant. They offer even greater benefits where existing preheaters are approaching the end of their useful life – maintenance and operating costs are starting to escalate, and replacement becomes the preferred option.

Howden has over 160 years of experience in air and gas handling equipment, and a worldwide reputation for engineering of the highest quality. We have been associated with rotary regenerative air heaters since 1923, when we set up a joint venture company with Fredrik Ljungström to develop the technology. Over the subsequent 85 years, we have been involved in research and development designed to improve efficiency and performance. For many decades, our equipment has been utilised in critical applications of all kinds throughout the world.

Compact, versatile and highly efficient

For the first time, rotary regenerative heaters at the lower end of the size range are being engineered to meet the economic and environmental circumstances of the foreseeable future, rather than the vastly different conditions that prevailed three or more decades ago.

Size 20

Package air heater size

Package air heater sizing with flue gas mass flow (only for reference) Package air heater sizing with recovered energy (only for reference)

Gas temperature drop 250˚C

Notes: Flow and MW recovered are based on normal operating conditions.

Gas temperature drop 200˚C

Gas temperature drop 150˚C

0

50

100

150

200

250

15.0 15.5 16.0 16.5 17.0 17.5 18.0 18.5 19.0 19.5 20.0 20.5 21.0 21.5

Package air heater size

15.0 15.5 16.0 16.5 17.0 17.5 18.0 18.5 19.0 19.5 20.0 20.5 21.0 21.5

To

ns p

er h

our

02468

1012141618

MW

Package air heater size

Package air heater sizing with flue gas mass flow (only for reference) Package air heater sizing with recovered energy (only for reference)

Gas temperature drop 250˚C

Notes: Flow and MW recovered are based on normal operating conditions.

Gas temperature drop 200˚C

Gas temperature drop 150˚C

0

50

100

150

200

250

15.0 15.5 16.0 16.5 17.0 17.5 18.0 18.5 19.0 19.5 20.0 20.5 21.0 21.5

Package air heater size

15.0 15.5 16.0 16.5 17.0 17.5 18.0 18.5 19.0 19.5 20.0 20.5 21.0 21.5

To

ns p

er h

our

02468

1012141618

MW

Package air heater sizing with recovered energy (only for reference)

Package air heaters are available in sizes ranging from 15-21

Package air heater sizing with flue gas mass flow (only for reference)

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Exceptional experience that brings practical benefits Our worldwide experience, supported by leading edge R&D and wind tunnel facilities, enables us to take an integrated approach to all aspects of air preheater technology.

Our designs are built on tried and tested technology while taking advantage of the economies brought by state-of-the-art computerised design. We have developed a modular approach that brings substantial and measurable system improvements into industrial package heater units customised precisely to customer needs.

The Howden pre-engineered package heater offers significantly reduced leakage, better thermal performance, greatly improved cleanability, ease of maintenance and exceptional long-term reliability. Our research in recent years has been driven by the global

need to reduce fuel consumption and minimise environmental impact, and these industrial preheaters incorporate developments that have already proven their value in highly critical applications.

For replacement heaters in existing plants, we provide new equipment that matches the previous unit while bringing vastly improved efficiency and thermal performance. We fit the package to existing foundations, ductwork, power supplies and other site arrangements, introducing valuable gains in performance and reliability with the minimum of on-site work.

By integrating our depth of experience with leading-edge 3D design software, we have made significant reductions in engineering time and cost. We have developed a full set of parameters for each component of the air preheater package, and can now use that data to create a machine to a precise specification, add the desired ancillary equipment, make adjustments to optimise the overall performance and match the heater to its final installation.

Throughout the design process, each individual part and the entire assembly can be freely rotated and minutely examined on screen in 3D representations. Once it has been comprehensively checked, finalised and approved, finished production drawings are produced very quickly. Once an order has been placed, the heater can be in production within weeks.

To carry the time advantage through to shipping, installation and commissioning, whenever feasible the heaters are pre-assembled in the factory and delivered as a single unit ready to be slotted into place. Larger units, of around size 17.5 and over, are supplied partially assembled in a way that optimises transport logistics and site installation.

The design advantage

Drive unitHorizontal package heater

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Customised configurationWe supply industrial package heaters in sizes up to 21.5 in both vertical and horizontal configurations, and virtually every parameter can be modified or changed to suit the application and duties of the heater and the preferences of the customer. Heaters up to size 17.5 are housed in a square casing with no need for transition ducts, and size 18 and above are in octagonal casings with transition ducts. These factors are, however, fully customisable at the customer’s request.

Reduced leakage and fuel costsOne of the most significant advancements we have introduced is the use of effective seals in this size range. An effective sealing system substantially decreases FD fan power consumption and increases performance of equipment downstream from the air preheater. These are highly sensitive issues now and likely to grow even more important in the future. We install as standard double axial seals and either single or double radial seals configuration as required. Our principle task is to match the heater we supply to the exact performance parameters set by the customer.

The design advantage

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Vertical air heater

The packages we supply are designed to include all of the required components and systems ready for coupling into the plant on site.

Horizontal air heater

More than the sum of the parts

7

6

2

1

8

8

9

3

3

Transition ducts

Side withdrawal door

Radial seals

Heating elements

Bearings

Bearings

Wash connection

Bearing housing and trunnion cooling system

Bearing housing and trunnion cooling system

5

4

Alarms and monitoring

Drive unit

2

1

Radial seals

Heating elements

6 Inspection door

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1. Heating elements

We have unrivalled experience in heater element design, and can provide profiles, materials and finishes to match any application. Fortunately, Howden’s custom designed performance selection program allows us to simulate the performance of any type of rotary regenerative air heater under changing operating conditions.

Skillful use of this program by experienced engineers allows us to compare the operation of the heater under current conditions with the original design specification. Thereafter, we can study the possible performances of the heater with a range of the alternative element profiles that we have at our disposal. Such a study allows us to recommend the optimum element selection for present or future operating conditions and demonstrate the advantages that the new element selection will bring.

The Howden SurePack Elements™ basket uses computer-controlled presses to introduce precisely the right degree of pressure prior to welding, providing optimum rigidity and guarding against damage to the element profile or enamel coating.

2. Axial and radial seals

The seals we have incorporated are based on our tremendous experience in large-scale heat exchangers. We use single leaf proximity seals designed for optimum effectiveness at normal operating temperatures, and we install as standard double axial seals and either single or double radial seals configuration as required.

To ensure that the leakage figures are maintained at the lowest level over the full working life of the heater, all of the seals are designed as consumables and are fully and easily replaceable on site.

3. Bearing housing and trunnion cooling system

The bearing from the hot side is refrigerated as standard with a water cooling jacket and in case of high gas inlet temperature a rotatory joint is used to refrigerate the trunnion.

4. Drive unit

We can supply either central or peripheral drives as standard. Unless there are strong reasons to choose peripheral (rack and pinion) drives, we strongly recommend the use of central motors. They offer greater economy, easier installation and replacement and, by removing the need for a rack, they allow axial seals to run the full length of the rotor and thus contribute to leakage reduction.

Backup drives are a standard option, and both electric and air motors can be supplied. Frequently, the preferred combination is an electric main drive and an air motor for backup.

5. Alarms and monitoring

In addition to oil temperature and rotation monitoring as standard, we can fit fire detection sensors and firefighting lances if required.

These options and configurations have been selected to offer the greatest flexibility to the customer while maximising the benefits of our parameterised design process. In this way, we can ensure that the heater is engineered as an integrated unit with every aspect of its performance optimised for its unique specification and duties.

6. Side withdrawal door and inspection door

For easy removal of baskets, a side access door is installed. This prevents the need for removing the hot end baskets to gain access to the cold-end baskets. In some designs an inspection door is installed for inspecting the seals.

7. Transition ducts

We supply package heaters ready to fit into the existing or planned ductwork of their destination. Where the heater is supplied in an octagonal casing, this normally involves the fitting of transition ducting to create a square profile. However, we can supply transition ducts if required.

8. Bearings

We use only the highest quality bearings sourced from premium manufacturers and have introduced a new bearing system that allows axial movement in the shaft to accommodate thermal expansion in the rotor.

9. Wash connection

Our design includes a wash connection washing pipe for off-line cleaning during overhaul. Additionally, we can supply semi-retractable or retractable sootblowers for cleaning purposes. The cleaning/washing devices can be adjusted or adapted to suit the configuration, fuel and system requirements of the heater.

7

9

Transition ducts

Wash connection

4 Drive unit

5 Alarms and monitoring

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Positive forward planning: time to upgrade The cost of repairing and maintaining package heaters that are more than twenty years old should be carefully balanced against the potential benefits of replacement.

Apart from the ever-increasing need to maximise the benefits we draw from our limited supplies of fossil fuels and to reduce environmental emissions, there are compelling economic reasons to make the change as part of the strategic forward planning of the plant.

The cost of repairing and maintaining package heaters that are more than twenty years old should be carefully balanced against the potential benefits of replacement.

Primarily, there is the need to balance the capital investment, a figure greatly reduced by our parametric design and production processes, against both the maintenance budget, which naturally increases as the heater becomes older, and the increasing possibility of an unplanned outage due to fouling, plugging or other failure. The costs associated with maintaining an aging heater to operate at the operation level necessary for optimum boiler performance combined with the increased risk of unplanned outages can be more than those of replacement with an updated and efficient Howden industrial package heater. The argument for a serious examination of the costs and savings are powerful even from this standpoint.

A new Howden package heater is not simply a replacement in-kindDespite the fact that it is designed to fit, like a direct placement, into the existing foundations, ductwork and power supply of your existing heater – its components is state-of-the-art technology customised to meet your demanding requirements.

In addition to the reduction in maintenance worries and costs, there are significant savings arising from greatly enhanced fuel efficiency. The combination of vastly reduced leakage, better thermal performance from improved element designs and packing, and much better cleanabilty to maintain the efficiency and reduce fouling, adds up to a significant reduction in running costs and, a factor that is becoming even more important, improved environmental responsibility.

The opportunity to introduce these improvements in a planned and phased way, during scheduled downtime for maintenance for example, should be carefully considered.

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The speed and ease of replacement means that the installation process can be accelerated, and the payback in reduced operating and maintenance costs, and peace of mind, is considerable.

Howden industrial package heaters are designed to deliver trouble free, round-the-clock operation with minimal planned maintenance. Our air preheaters are supported by a full commitment to after sales service and spares.

Regenerative heater technology does not stand still. Our policy is always to design for future upgradeability, and we are happy to advise on ways of incorporating the latest developments into the equipment we supply. Howden engineers are readily available throughout the world for consultation, service and support.

Looking towards the future

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www.howden.com

©Howden Group Limited. All rights reserved. 2015.Howden and the flying H logo are registered trade marks belonging to Howden Group Limited.

At the heart of your operationsHowden people live to improve our products and services and for over 160 years our world has revolved around our customers. This dedication means our air and gas handling equipment adds maximum value to your operations. We have innovation in our hearts and every day we focus on providing you with the best solutions for your vital operations.

Howden Spain

Ctra. F-40, km. 1 a Los Camachos 30360 La Union, Murcia, Spain

Tel: +34 968 32 00 64 Fax: +34 968 50 60 77 Email: sales.hs@howden.com