HEADER-TYPE HEATER - Balcke-Dürr

balckeduerr

HEADER-TYPE HEATER - Balcke-Dürr

More flexible, more durable, more profitable:

HEADER-TYPE HEATER

There are very good reasons why high-pressure feedwater heaters

of the header type, shortly called header-type heaters, have been

used for many decades in almost all large coal-fired power plants

in Europe, South Africa and Australia:

They offer excellent technical and commercial advantages

over conventional U-type high-pressure heaters, also known as

tubesheet-type heaters. They permit much greater power plant

operation flexibility with a higher number of load changes and

last up to four times as long. In addition, they are by far a more

cost-effective solution, both in terms of investment and operating

costs. In short, header-type heaters are a superior heat exchanger

technology that is gaining popularity around the world.

The high pressures of supercritical water/steam cycles require the

tubesheet walls of U-type heaters to be extremely thick. Irreparable

thermal cracks often occur at the joints with the thin shell after

just 10 to 15 years of operation. In addition, the especially large

feedwater mass flows make it necessary due to construction

reasons to arrange twice the number of U-type heaters in two

parallel piping trains.

In contrast, header-type heaters have a service life without repairs

of up to 50 years thanks to their excellent thermo elasticity and

can be arranged in a single piping train, which reduces the cost of

piping, valves and buildings.

Advantage of header-type heaters due to single-train arrangement

PROFILE

■ World’s No. 1 supplier of header-type heaters

■ Designer and manufacturer of header-type heaters since 1935

■ Over 1,200 references for header-type heaters in 100 to 1,100

MW power plants

■ Proven technology with convincing advantages over U-type

heaters:

– More flexible power plant operation

– Longer service life (up to 4 times longer)

– Lower investment and operating costs

3D model of a header-type heater

■ Designs for vertical and horizontal installation

■ Almost zero failure rate (0.00015 %) in approximately one

million installed snake tubes

■ Special device to plug snake tubes is available

■ Easy access to the headers through inspection opening with

self-sealing cover


TECHNOLOGY

As nuclear power plants are frequently operated according to

Unlike in U-type heaters, the water and steam sides in header-type

heaters are separated by two thick-walled pipes, the inlet and outlet

headers, instead of by a tubesheet. Moreover, the heat exchanger

tubes are arranged in a snake shape instead of U shape, generally

in 3 or 4 water passes through the shell area.

A complete high-pressure heater train generally consists of three

header-type heaters and a separate desuperheater. The heaters

are installed vertically in most cases and only rarely horizontally.

Header with snake tubes

Fabrication of header-type heaters is more complex than for U-type

heaters. Special attention is paid to the connections between the

headers and snake tubes, which are welded together indirectly

using nipples. The automated welding process used is especially

reliable. In the over 1,200 header-type heaters manufactured

since 1935, with around one million tubes, only 15 tubes had to

be plugged.

Nipple

Snake tube

Header

Header-to-tube joint

BALCKE-DÜRR AMERICAS

A DIVISION OF SPX COOLING TECHNOLOGIES, INC.

7401 W 129 STREET

OVERLAND PARK, KANSAS 66213

UNITED STATES

913 664 7428

bdinfousa@spx.com

balcke-duerr.com

In the interest of technological progress,

all products are subject to design and/or

material change without notice.

©2009 SPX Cooling Technologies, Inc.

Printed in USA | brochure_na_46

Investing in header-type heaters instead of U-type heaters usually

pays off in power plants with nominal capacities from about 500

MW. Above this threshold, investment costs for U-type heaters

escalate since they must be arranged in two trains instead of in

a single train. Consequently, the cost of equivalent header-type

heaters is generally exceeded. Maintenance costs for U-type

heaters are much higher in large power plant units or in cycling

operation because heaters of this type are susceptible to damage

and require frequent repairs and not seldom must even be

completely replaced.

APPLICATION

450 MW Avedöre 2 coal-fired power plant, Denmark:

The four header-type heaters were manufactured in the Neubeckum

facility and have been operating since 2000.

Tube bundle in the manufacturing facility

950 MW Niederaussem K lignite-fired power plant, Germany:

Equipping one of the world’s most modern lignite-fired power

plants (BoA 1) with header-type heaters (2000).

Header-type heater during installation in the power plant

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