Table Of ContentCOMPLETE LIST OF TITLES IN THE SERIES
Vol 1 OSBORNE
Fans 2nd Edition
Vol 2 EDE
An Introduction to Heat Transfer Principles and Calculations
Vol 3 KUT
Heating and Hot Water Services in Buildings
Vol 4 ANGUS
The Control of Indoor Climate
Vol 5 DOWN
Heating and Cooling Load Calculations
Vol 6 DIAMANT
Total Energy
Vol 7 KUT
Warm Air Heating
Vol 8 BATURIN
Fundamentals of Industrial Ventilation
Vol 9 DORMAN
Dust Control and Air Cleaning
Vol 10 CROOME & ROBERTS
Airconditioning and Ventilation of Buildings
Vol 11 CROOME
Noise, Buildings and People
Vol 12 ME ACOCK
Refrigeration Processes.
A Practical Handbook on the Physical Properties of Refrigerants and their
Applications
Vol 13 MACKENZIE-KENNEDY
District Heating - Thermal Generation and Distribution.
A Practical Guide to Centralized Generation and Distribution of Heat Services
DISTRICT HEATING
Thermal Generation and Distribution
A practical guide to centralised generation and distribution of heat services
by
C. MACKENZIE-KENNEDY
CEng, MIMechE, MemVDI
PERGAMON PRESS
OXFORD · NEW YORK TORONTO SYDNEY PARIS FRANKFURT
U.K. Pergamon Press Ltd., Headington Hill Hall,
Oxford OX3 0BW, England
U.S.A. Pergamon Press Inc., Maxwell House, Fairview Park,
Elmsford, New York 10523, U.S.A.
CANADA Pergamon of Canada, Suite 104, 150 Consumers Road,
Willowdale, Ontario M2J 1P9, Canada
AUSTRALIA Pergamon Press (Aust.) Pty. Ltd., P.O. Box 544,
Potts Point, N.S.W. 2011, Australia
FRANCE Pergamon Press SARL, 24 rue des Ecoles,
75240 Paris, Cedex 05, France
FEDERAL REPUBLIC Pergamon Press GmbH, 6242 Kronberg-Taunus,
OF GERMANY Pferdstrasse 1, Federal Republic of Germany
Copyright© 1979 C. Mackenzie-Kennedy
All Rights Reserved. No part of this publication may be
reproduced, stored in a retrieval system or transmitted
in any form or by any means: electronic, electrostatic,
magnetic tape, mechanical, photocopying, recording or
otherwise, without permission in writing from the
publishers.
First edition 1979
British Library Cataloguing in Publication Data
Mackenzie-Kennedy, C. District heating.
(International series in heating, ventilation
and refrigeration; vol. 13)
1. Heating from central stations
I. Title II. Series
697'.54 TH7641 78^0890
ISBN 0 08 0227112
In order to make this volume available as economically
and as rapidly as possible the typescript has been
reproduced in its original form. This method
unfortunately has its typographical limitations but it is
hoped that they in no way distract the reader.
Printed and bound at William Clowes & Sons Limited
Beccles and London
Foreword
Peter L. Rost, M.P.
Member of the Select Committee,
Science and Technology, Energy Resources
While we continue complacently to neglect the promotion of combined heat and power
in this country, any energy conservation programme will fail to tackle a major
area of waste·
For while two-thirds of the energy used to fuel our power stations is rejected we
9
will continue to throw away 20/6 of our total energy· That scandalous waste repre-
sents almost the whole contribution made by natural gas to our 1977 energy supplies·
or more than half our hard-won coal output·
The blame for our failure to use energy more rationally lies with the politicians.
Government has established and sustained an institutionalised monopoly in the
electricity supply industry, which has hindered co-generation, even where it can
be shown to be cost-effective· Meanwhile, the consumer pays for the continuing
waste of resources. Low income families, particularly the elederly and house-
bound, are trapped in electrically heated homes they cannot afford to heat· The
nation as a whole hae to pay for the continuing construction of power stations
which reject the heat which consumers have to go without !
What is a scandal today could become a disaster in the future, unless we provide
the political initiatives and economic incentives which will utilise the energy
we now waste« For as fuel prices rise in real terms« so will the effect on our
national economy and hardship to the consumer·
As one who believes in the inevitability of combined heat and power in this country«
who regrets that we are bottom of the European league« and can see what needs to
be done« I welcome this book· It offers an informed« well researched and timely
contribution to what is now a national debate· The constructive case it présente
in support of the belated recognition that it is time for action« should make it
an important catalyst which will influence the course of events·
Peter L. Rost
Mouse of Commons
1978
vii
Preface
The fuel crisis year 1973 brought forcibly to universal attention the fact that
world resources of certain fossil fuels, upon which most of the ever rising living
standards are fully dependent, are fundamentally finite· With approach of anti-
cipated and forecasted critical shortages of oil and gas by the turn of the
century, all fuel prices are liable to rise to levels uhich by presentday standards
may well be considered beyond economical realism·
During the 1962-1972 boom-decade of primary energy consumption, the use of oil and
natural gas rose astronomically at the expense of solid fuels· Prices of all fuels
reached their lowest ever relative levels, with coal always plentifully available
for long-term exploitation, becoming "unfashionable" because of comparative
difficulties and costs associated with its mining and untidiness of its storage,
transport and utilisation; this being also related to rising labour costs commensu-
rate with improving social standards· Utilisation of coal therefore rather stagna-
ted and the less labour intensive techniques associated with combustion of oil and
gas were extensively applied·
With reference to anticipated shortages and price increases of fossil fuels, much
interesting research into possibilities of making use of such natural phenomena
as wave power, solar heat, heat pumps, geothermal heat, etc., must be mentioned.
As individual projects, these are without a doubt well worth consideration, but at
this juncture and as 100% replacement for fossil fuels, they can but be looked
upon as "pie-in-the-sky"· Much hope rests with nuclear power; again many problems
are still to be resolved before it can take over to a major extent, the current
fossil fuel commitment. In any case it is hardly likely that suitable nuclear
plants would be made in sizes to suit the average private heating system of a
family dwelling. Therefore, even with major replacement of power station plant by
nuclear fuelling, centralised thermal generation would be required and efficient
interconnection of minor and major heating networks provided earlier, would
nevertheless be essential.
The author will not attempt to analyse the vast number of statistical estimates
and prognoses published and debated regarding the future of fossil fuels; the trend
is quite clear and cannot be contested and reversed. Utilisation of fossil fuels
at a much faster rate than nature can provide, must therefore be expected well
into foreseeable future.
Domestic services consume a large proportion of conventional fuels and experience
shows that it is considered desirable and democratic to have one's own heating
system. Boilers and other appliances used for such systems may make effective
use of 35% - 45% of the fuel heat input and therefore some 55% would be discarded
to waste with consequent loss in terms of fuel costs. Unavoidable future relative
increases in fuel prices will make such monetary losses much more serious. Modern
electrical power stations operating at their higher thermal efficiencies of 36%
discard some 64% of fuel heat. These two cases alone indicate the staggering
IX
X Preface
overall inefficiency and extravagance of present-day fuel utilisation, to which
must be added the aspect of environmental pollution by the many individual heat
users·
The one source of fuel not likely to experience depletion in the foreseeable
future, but rather improve in quality and quantity, is domestic and industrial
refuse and waste, which by its very nature can also become a hazard to health
and environment· The most effective and sterile disposal of such waste products
is by high intensity incineration and apart from consequent sanitary elimination
it has been proved that the average heat value of refuse is roughly one third
that of coal·
In this book attempt is made to depict various practical ways and means of
utilising thermal energy from various sources in order to provide centralised
generation and subsequent distribution of heat services and to illustrate
recognised and proven practices as applied in different countries·
Discourses on techniques, plant and distribution methods are included, indicating
advantages and drawbacks as fully as permitted by space available·
The author is exceedingly grateful to Mr Peter Rost, M.P., for so kindly
contributing the foreword to this book«
York C. Mackenzie-Kennedy
1978
Acknowledgements
The author is greatly indebted to the numerous colleagues and firms who provided
much information and many illustrations in order to assist in the compilation of
this book· Acknowledgement is due to the following:
Allen Ygnis Boilers Ltd·, Tipton.
A.M.E. - Heizung GmbH·, Bielefeld. Herrn Ing. G. Kienast·
Armstrong Pumps Ltd., Colchester.
Anglo Nordic Thermal Holdings Ltd·, Kingston upon Thames.
B· & E· Boilers Ltd., Bracknell.
Deutsche Babcock & liiilcox A. G·, Oberhausen·
Eisenwerk Baumgarte GmbH., Brackwede. Herrn Dipl.Ing. Hans Baumgarte.
Greis Berg, Esq., MSc (Eng), A.B. Energikonsult, Stockholm.
Bruun & Sorensen Ltd., Aarhus. V. Mickelsen, Esq., J. Taylor, Esq.
Buderus'sche Eisenwerke, Eversbach.
Caliqua liiaermegesellschaft mbH·, Darmstadt·
Clorius Meters Ltd., Bradford. G. C· Towler, Esq.
District Heating Association, Caterham.
GKN - Birwelco Ltd., Halesowen. A. L. R. Marx, Esq.
Hamworthy Engineering Ltd., Combustion Division, Poole.
A. E. Haseler, Esq., C. Eng., FIEE FCIBS FFB.
Kabel und Metallwerke Gutehoffnungshuette A.G., Hannover. Herrn Ing. V. Härders.
H. Kranz liiaermetechnik, Aachen. Herrn Ing. Hans Dauber.
Eisenwerk Theodor Loos GmbH·, Gunzelhausen·
Rud. Otto Meyer, Hamburg· Herrn Ing. Wilhelm Orfert.
Gebr. Flickeleit GmbH., Koeln. Herrn Dipl. Ing. Harry Friedrichs.
Mirrlees Blackstone Ltd., Stockport·
xi
xii Acknowledgements
Mollerpipe Ltd., Hounslow.
POotheruell Bridge Tacol Ltd., Croydon.
Mustad Industrier A.5., Oslo.
Kymi Kymmene Engineering, Heinola.
D. 3. Neil Ltd., D. 3. Neil, Esq., Nacclesfield.
Nottingham Corporation District Heating, Nottingham. R. G. Ambler, Esq.
Parkinson Cowan GWB Ltd., Dudley.
Princes Development Co. Ltd., Windsor.
Ranger Instruments Co. Ltd., Basingstoke.
South Yorkshire C.C., Sheffield Incineration Authority. J. R. Holmes, Esq.
Stadtuerke Saarbruecken A.G., Saarbruecken. Herrn Dipl. Ing. Johannes Flad.
Stal-Laval (G.B.) Ltd., London. H. Harboe, Esq.
F. Stienemeyer KG., Hamm. Herrn Siegfried Stienemeyer.
Verein Deutscher Ingenieure - Verlag GmbH., Duesseldorf.
Von Roll A.G. Zuerich. Environmental Department.
Max Ueishaupt GmbH., Schuendi. Herrn G. Huck.
T. Wuppermann GmbH., Uipperfuerth. Herrn Dipl. Ing. Genscher.
CHAPTER 1
Introduction
GENERAL REMARKS
Modern developments and trends in town and commercial planning indicate that with
few exceptions, concentrations of dwellings, industrial complexes and other groups
of buildings can have only one genuinely efficient and economical solution to the
problem of providing heat services for the population; this solution is district
heating·
Past Experiences
District heating is not a new concept, although in Britain its serious initiation
did not materialise until after the Second World War· Prior to 1939 coal was cheap
and plentiful, the cost and wellbeing of labour was not as critical a consideration
as today and little attention was paid to environmental and air pollution. Indivi-
dual open coal fires formed the staple means of providing residential and a large
proportion of commercial accommodation with a certain degree of warmth at a thermal
efficiency of 10 - 12 per cent, albeit with much smoke and loss of heat, although
individual coal and coke fired boilers were also used for comparatively minor
central heating of schools, office blocks and other functional buildings by means
of hot water or steam radiators. Of course industrial complexes frequently offered
better standards because of the availability of surplus steam as used for industrial
heat, generated in indestructible Lancashire boilers and other similar smoky heat
producers. In the past it has often been a "tongue-in-cheek" contention that the
Gulf Stream climate and inherent hardiness of the population combined to make life
on the British Isles bearable; any unexpected excesses in low winter temperatures
(which seemed to occur very frequently) became useful for maintaining full employ-
ment of metereological statisticians, provided a traditionally excellent subject
for small talk and in any case could always be counteracted by means of 750 watt
electric fires. It may possibly not be surprising that numerous varieties of
rheumatic ailments were much in evidence.
In the past years the fuel and labour syndrome also applied to other countries
enjoying climatic conditions not dissimilar to those in Britain, (excluding the
Gulf Stream, of course) also environmental pollution was not given much thought;
it was however realised by the inhabitants that under certain winter ambient
conditions, man's own natural source of heat generation was not adequate to allow
him to perform his everyday toils and chores in reasonable comfort and without
consequent reduction in productive effort and absenteeism caused by sickness.
1
2 District Heating - Thermal Generation and Distribution
Recent Interpretations and Design Criteria
Some property developers, in order to economise on first cost investments in
rentable new buildings, installed so-called "central heating" in the form of
off-peak electricity, a very costly type of heating which cannot possibly
constitute anything more than "background warming"·
It is not intended to enlarge upon details and analyses of past and present day
environmental influences, nor upon modern realistic appreciation as to what
constitutes a condition of comfort and well-being; detailed information related
to such criteria and associated design data as well as statistical assessments are
nowadays available within the context of numerous excellent transactions and
publications, such as the IHUE Guide· Sufficient to say, the Continent of Europe
and the United States, be it within our own range of degree days or In areas
having colder climates, took cognizance of the facts related to man's comfort
rather earlier than we did and laid down mandatory design criteria to safeguard
indoor conditions of comfort in winter· As an example, dictated by altitude
above sea level and geographical location, Germany uses base ambient design
temperature criteria of -12 C to -18 C in conjunction with indoor living space
temperature of +18 C. Even the south of France refers heating design to -3 C
winter ambient· In the past the British recommended outdoor standard was quoted
at 0 C (32 F) for +18 C indoors· This ambient base temperature has been amended
to a more realistic and flexible range of -2 C to -3 C, as a result of
recommendations by professional bodies.
Conservation of resources. Present day policies for conservation of fuel
resources and their high cost may well have some effect upon mandatory design
regulations as implemented in some Continental countries, whose standards are to
a great extent based upon comparatively short-period low temperature troughs. In
order to ensure efficient and positive control of heat distribution to avoid
seasonal waste, the provision of extremely sensitive and sophisticated (hence
expensive) control equipment, reacting upon distribution temperatures, outdoor
conditions and water flows, becomes imperative. Statutory design criteria should
therefore be capable of achieving an economic balance between first cost and
operational economies without sacrifice in overall performance·
In order to create and maintain high living and environmental standards, most
countries introduced central heating by steam or hot water as a rule rather than
an exception. Many foreign countries also appreciated the considerable economical
advantages offered by district heating. Right from the start, a more rigorous
design base can offer greater economies both in first cost and cost per thermal
unit because of greater possible distribution density.
Principles and yardsticks. Universally the term "district heating" applies to the
principle of utilising a centralised thermal source to provide distributed heat
services to a number of different customers and the designer's primary duty is to
plan a system for distribution of the services over as large an area as possible
containing as many customers as economically feasible. The system should ensure
the utmost efficiency in distribution of heat and a heat load density within
economic limits of transmission over the area to be served, in relation to first
cost investment. Certain planning criteria related to degree of concentration
of users, must apply, i.e. extensive networks in order to provide widely distri-
buted minor customers, are obviously not economical because of high first cost
of distribution mains and the operational heat loss. During the late sixties,
attempts were made to determine economic yardsticks for desirable area heat
densities, network heat loads per unit of heat generated, lengths of distribution
