Process Engineering Equipment Handbook Episode 2 Part 4 pdf

programs focus on raw material selection and a more precise phosphorus allocation,
and the addition of phytase enzyme to improve phosphorus utilization.
Suomen Rehu has been able to reduce the amount of added phosphorus by
almost 700 t/a in poultry and pig diets between 1995 and 1997. This enables the
reduction of the phosphorus content of manure by 30 percent, which in turn
promotes environmentally compatible livestock production and enables farmers to
increase the number of animals they keep.
Feeding management can also be utilized in developing poultry diets without any
added growth promoter substances with an antibiotic effect; and pork diets without
any added growth promoters. As a result of these types of feeding programs, the
proportion of feeds produced by Suomen Rehu without such additives has steadily
increased. In 1997, 85 percent of the pigs fed with Suomen Rehu feeds received
diets without any added growth promoters.
ISO-VILJA
TM
technology, developed by Suomen Rehu, is a commercial quality and
environmentally oriented cultivation concept. Targeted nutritional content and
feeding value, controlled quality with respect to product hygiene and residues, and
traceability from cultivation to transportation and the feed factory are the most
significant features of ISO-VILJA
TM
technology.
ISO-VILJA
TM
is used by Suomen Rehu to enhance the quality of raw materials
used for feed manufacturing. A transparent, documented quality chain for animal
production and livestock-based foodstuffs is employed.
The benefits of ISO-VILJA
TM
technology to the farmer include better profitability

as a result of higher yields and significant savings in fertilizers. In addition,
residual nitrogen in the soil can be reduced by up to 60 percent. In 1997, 1600
farmers adopted this cultivation method, 3000 farmers received training on the
E-46 Environmental Accountability
TABLE
E-8 The Most Significant Environmental Incidents at Business Units between 1995 and 1997
Cultor Business Sector/Division Accident or Leakage
CFS Xyrofin, Kotka, Finland A discharge valve of a caustic (NaOH) storage tank was accidentally left open in summer
1996, causing a leak of 22.5 tonnes of caustic soda into the sea. A capital project for a
new storage tank and distribution system was undertaken as corrective action.
CFS Xyrofin, Kotka, Finland In summer 1997, wastewater was discharged into the sea for seven days (approximately
120 hours in total) due to pretreatment, electricity, and wastewater treatment system
failures.
CFS Flavor Technology A package containing ethanol-based flavoring products was shipped improperly from the
Corporation, East Windsor, U.S. facility in summer 1997. Penalties of FIM 52,000 have been paid. This led to changes in
risk management in the shipping of hazardous materials
Cultor Baking, Vaasan Baking, An oil leakage took place in summer 1996 as a result of old pipelines and corroded valves.
Nelo Bakery, Finland The soil was treated immediately in cooperation with the authorities.
Cultor Nutrition Finnsugar, Fire damage in summer 1997. No damage to the environment or production resulted.
Kantvik, Finland
Cultor Nutrition EWOS, Scotland 1) Land near the factory was previously used for landfill between 1993 and 1996.
Landscaping and clean-up was carried out during 1997. Clean-up costs totalled FIM
640,000.
2) Fish oil leakage into a stream took place in summer 1996. A total of FIM 3600 in fines
were paid.
3) Fish oil leakage into a stream in late 1996 and early 1997. The case was treated
immediately in cooperation with the authorities. No legal action was taken.
4) Fuel oil leakage in summer 1997 as a result of the failure of old pipelines. Clean-up
costs totalled FIM 210,000. A total of FIM 18,000 fines were paid. The wastewater
system mentioned on Page 29 in this report will reduce the risk of contamination of the

local water system from taking place in the future.
Cultor Feed Ingredients
᭿ To reduce odor generated by betaine production at the
Naantali plant.
᭿ To implement documented quality and environmental
management systems.
᭿ To reduce effluent loadings and improve energy
efficiency at Pacific Protein.
Cultor Baking
᭿ To develop the concept of controlled farming.
᭿ To improve health and safety at bakeries.
Cultor Nutrition
FINNSUGAR DIVISION
᭿ To further reduce the environmental impact of sugar
beet cultivation. To incorporate environmental
management in the quality management system.
᭿ To finalize the LCI (Life Cycle Inventory) on sugar beet
and its main products in 1995.
᭿ To further reduce the environmental impact of drying
beet pulp.
᭿ To promote the recovery/recycling of packaging waste
and increase the use of bulk transportation.
EWOS
᭿ To further reduce the environmental impact of fish
farming.
᭿ To develop alternative protein sources for fish feed
production.
SUOMEN REHU
᭿ To further improve the division’s environmental
management system and reinforce the image of

Finnish food as clean and wholesome.
New objectives
Implementation of Cultor’s sustainable development value
process
Environment
Quality
Regulatory and ethical issues
᭿ A study was initiated in 1997 to explore suitable biological
methods for an odor treatment investment. This will be
completed in mid-1998.
᭿ Enzyme operations received ISO 9001 certification in 1994,
and Betaine operations ISO 9002 certification in 1997. The
certification target for ISO 14001 covering both operations
was 1999.
᭿ An investment has been made in pretreatment of
wastewater and heat recovery systems.
᭿ Investments in flour dust removal systems at various
bakeries.
᭿ Further work has been done, together with the Sugar Beet
Research Centre. Goals have been set as part of
implementing the ISO 14001 standard.
᭿ The LCI was completed in 1995.
᭿ The overall nitrogen loading associated with fish feed has
been reduced by 80% over the last 20 years, and has now
reached the level where further improvements will be
difficult to obtain without affecting feed quality
properties.
᭿ Work has been done on soya as an alternative protein
source.
᭿ Suomen Rehu received ISO 14001 certification in 1996.

Value network thinking and supplier auditing have been
promoted. Improvements have also been made to feeding
management systems, and ISO-VILJA
TM
technology has
been introduced.
᭿ Develop Cultor’s environmental database to better meet the
needs of both the Group and divisions. Improve the
reliability of the data collected through the database.
᭿ Develop indicators for environmental, quality, regulatory,
and ethical issues to measure performance; and conduct a
pilot study to test the suitability of the indicators chosen.
᭿ Implement Cultor’s new Quality and Environmental Policy
in operations.
᭿ Develop documented quality and environmental
management systems for all of Cultor’s major business units
Divisions to set detailed targets and objectives.
᭿ Continue to conduct LCIs for major products and use LCIs
as an internal environmental management tool.
᭿ Start monitoring transportation data at Group level.
᭿ Improve the follow-up of H&S indicators at both Group and
divisional level. Develop the data collected and definitions
used.
᭿ Start using self-assessment as a Group-wide tool for
continuous improvement.
᭿ Continue internal benchmarking for process improvements
and start external benchmarking.
᭿ Start divisional cross-auditing.
᭿ Implement the new Regulatory Policy in divisional
operations. Create standard operational procedures based

on the policy and set goals for Cultor’s regulatory work.
᭿ Implement the Animal Trial Policy in divisional operations.
᭿ Implement the Modern Biotechnology Position Paper in
divisional operations.
᭿ Continue proactive dialogue with stakeholders, particularly
in the area of modern biotechnology.
TABLE
E-9 Environmental Report 1995 Objectives
Progress
technology, and 14,000 technical leaflets were distributed. (See Figs. E-39 through
E-41.)
Environmental reports
Objectives and targets. Table E-9 describes the progress that Cultor has made in
implementing the objectives detailed in its 1995 Environmental Report. New
objectives are also given, linked to four key areas: implementation of Cultor’s
sustainable development value process, the environment, quality, and regulatory
and ethical issues. The objectives and corporate target objectives are updated
annually.
E-48 Environmental Accountability
FIG. E-39 Taking a chlorophyll measurement on one of the farms using Suomen Rehu’s ISO-
VILJA
TM
advanced cereal farming concept. (Source: Cultor.)
Reference and Additional Reading
1. Soares, C. M., Environmental Technology and Economics: Sustainable Development in Industry,
Butterworth-Heinemann, 1999.
Environmental Air Monitoring (see Emissions)
Environmental Economics*
Environmental resources and effects are difficult to quantify using the usual
economic terms and definitions. “Environmental economics” includes special

Environmental Economics E-49
FIG.
E-40 Amount of inorganic phosphorus used at Suomen Rehu. (Source: Cultor.)
FIG. E-41 Pig feed production with and without growth promoters. (Source: Cultor.)
*Source: AssiDomän, Sweden. Adapted with permission.
additional costs and revenues generated by environmental measures, whether
compulsory or voluntary. A discussion of the term follows with specific reference to
the information source’s corporate policy.
Yardsticks of Environmental Economics (Reference Corporation: AssiDomän)
Biological diversity
External, independent certification of forestry preserves biological diversity at the
same time as active forestry is pursued. By means of the certification process, the
market can complement and hasten necessary legislation.
The development and introduction of new ecological forestry methods and
the certification process are viewed as investments in the future by companies
that practice them. The additional costs of these efforts within AssiDomän in 1995,
1996, and 1997 have been estimated at MSEK (millions of Swedish kronor) 100,
120, and 150, respectively. As the new methods gradually become the accepted
norm, the actual voluntary additional costs are estimated at half this amount.
Certification raises the value of forest assets, and certified products are expected
to yield additional revenues amounting to several tens of millions of Swedish kronor
for AssiDomän over many years.
These measures contribute strongly to improving global image as a proactive and
leading force in the environmental field. This is a particularly strong corporate
objective in western European countries, such as Sweden. In AssiDomän’s case,
much of the corporation’s holdings and the head office are in Sweden. However, it
has assets elsewhere, notably Germany.
Reduced emissions
Environmental measures to reduce emissions from the plants are undertaken in
response to local legislation, license conditions, environmental charges, and taxes,

and as voluntary investments. The Swedish legislation and licensing procedure
requires the best available technology within reasonable economic limits—an
effective stimulus to advances in environmental technology. Within AssiDomän,
efforts are being concentrated on reducing discharges of oxygen-demanding
substances to water, reducing emissions of acidifying sulfur and nitrogen oxides to
air, and energy conservation measures. Large environmental investments are often
undertaken as part of other major capital investments, particularly at pulp and
paper mills. The environmental capital cost is between 10 and 25 percent of the
project (around MSEK 300 in 1997 for AssiDomän). Environmental charges and
taxes amounted to approximately MSEK 50.
Note that some of these taxes are specific to individual countries. They are
not yet globally accepted practice. For instance, Sweden charges NO
x
and SO
x
taxes;
as of 2001, the United States does not.
Roughly 10–20 percent of the environmental investments can be regarded as
voluntary. In some cases they can yield direct additional revenues for products with
an environmental profile (goodwill investment, enhancing the company’s image,
name, and trademarks). See also Table E-10.
Some examples:
᭿
The new biofuel boiler in Frövi reduces the oil requirement, permits increased
biofuel use, and is projected to become increasingly profitable as energy taxes rise.
᭿
Ash restoration: Recovering the ashes from the wood-processing mills, treating
them and returning them to suitable soils will eventually be necessary due to the
E-50 Environmental Economics
threats of soil acidification and nutrient deficiency in combination with future

waste requirements and charges. Several trials are under way.
᭿
Reduced sulfur content in ship fuels: This voluntary measure incurred a short-
term additional cost for AssiDomän, but was more environmentally cost-effective
than alternative measures to reduce sulfur emissions. It influenced the decision
of authorities regarding environmental charges for shipping.
Research and development on cleaner and more energy-efficient processes
Research and development investments in the group amounted to around MSEK
210 in 1997. It is estimated that approximately MSEK 65 of these have a direct or
indirect link to the environment. These investments include the projects concerning
bleaching, air and water pollution control, and “ecocycles” that are for the most part
being pursued on a joint sectoral basis.
A unique AssiDomän project in cooperation with suppliers is black liquor
gasification, where a demonstration plant is planned at AssiDomän Kraftliner in
Piteå. This new technology is expected to become a breakthrough that will provide
higher energy efficiency and twice the production of electrical energy from biofuel.
The project has been granted state energy subsidies amounting to half of the
construction and experimentation costs totaling MSEK 475.
Environmental Economics E-51
TABLE
E-10 Some Environmental Key Ratios
Purchased
Electricity Fossil Fuels
(kWh/SEK
1
) (kWh/SEK
1
)
Type of Activity 1997 1995 1997 1995
AssiDomän’s five pulp 0.88 0.39 0.89 0.37

and paper mills
in Sweden
Industry, pulp and —
2
0.46
3
—
2
0.27
3
paper mills
AssiDomän’s corrugated 0.06 —
2
0.13 —
2
board and sack production
4
1. Value added is the sum of operating profit after depreciation and payroll
expenses.
2. No data available.
3. Energy consumption: source—ÅF-IPK, Energy Consumption in the Pulp
and Paper Industry, 1994 (in Swedish). Value added: source—SCB,
Industrial Statistics, 1995.
4. Applies to all plants in the Group.
NOTE: It is AssiDomän’s ambition to contribute to the development of
environmental key ratios that can describe how the environmental work
affects resource use and financial position. Since energy use is strongly
environment-related and furthermore an important cost item for the forest
products industry, AssiDomän’s energy use is reported here in relation to
value added. This reflects both the energy intensity of the company’s own

activities, and sensitivity to energy price changes.
The difference between 1995 and 1997 is explained for the most part by
the fact that the price level for the end products, and thereby the value
added, was considerably higher in 1995. It is of interest to note that energy
use in relation to value added is nearly 10 times lower in corrugated board
and sack manufacture than in the pulp and paper mills. The table also shows
that AssiDomän is at roughly the same level as the rest of the Swedish pulp
and paper industry.
Energy price sensitivity is shown by the fact that when converted to energy
costs, the expenditures for electricity and fossil fuels correspond to 10–20
percent of the value added.
Development of resource-efficient packaging
Development of more resource-efficient, lighter-weight, and more transport-efficient
packaging is not just environmentally, but also often economically desirable. (See
Fig. E-42.) Life-cycle assessments (LCAs)* as a basis for the development work
are an important tool here. The potential for commercial exploitation of the
environmental benefits is greater if these benefits can be promoted as part of a new
product or packaging solution.
Examples of such projects within AssiDomän are:
᭿
A stronger sack paper that enables the density of the paper to be reduced by more
than 10 percent for certain applications. See Fig. E-42.
᭿
The launch of the board Frövi Light. An example: 25 percent reduced board weight
for a frozen food pack in Germany resulted in fewer and lighter-weight shipments
plus MSEK 0.7 in reduced packaging charges for the customer.
᭿
New barrier-coated papers that replace aluminum-foiled papers, which are
difficult to recycle.
᭿

Continued promotion of “eco-white” kraftliner, based on a new process for
significantly more efficient wood and fiber utilization plus totally chlorine-free
bleaching. Thanks to the improved environmental profile, it has been possible to
speed up the market introduction, resulting in additional revenues of several tens
of millions of Swedish kronor.
Within the corrugated packaging business, a design and material optimization
program has been developed and has resulted in the launch of several new types
of packaging with both reduced material consumption and lower costs. One example
is a tray for detergent. The improved environmental profile convinced the German
manufacturer Henkel to choose this new packaging solution, permitting a 28
percent weight reduction.
Environmental management systems (EMS)
The total costs of work with EMS in the Group during 1997 is estimated to be about
MSEK 30. EMAS registration or ISO certification provides a strategic advantage
for customer relations, but is not expected to yield direct additional revenues.
However, it is noted that setting environmental objectives and plans entailed by
certification/registration can in the long run yield significant efficiency gains that
clearly outweigh the costs. See Table E-10.
Analysis of potential environmental debts is a part of ongoing EMS work. The
costs of rectifying environmental debts known today are estimated to be less than
MSEK 10.
Consequences for Long-Term Profitability
Specific environmental issues in AssiDomän are:
Conservation of the world’s forests
Widespread demands for increased protection of the world’s forests, including old-
growth forest in the northern coniferous forest belt, have led to restrictions and
E-52 Environmental Economics
* The term life-cycle assessment is used here with a different connotation from that of the entry “LCA,”
which concerns LCA of turbomachinery components.
Environmental Economics E-53

FIG. E-42 Long, strong fibers are a prerequisite for resource-efficient manufacture of strong
packaging. The photo shows spruce fibers at a magnification of 100 times. (Source:
AssiDomän.)
thereby some scarcity of high-quality softwood timber. AssiDomän’s vast holdings
of forest land are one of the group’s most important assets in this context, and
certification of these holdings further enhances their value.
Emission requirements and environmental charges
Completed environmental investments have given AssiDomän and most other
Nordic pulp and paper mills a lead over many international competitors—a lead
which can often amount to several hundred million Swedish kronor in investments
per mill. In Sweden, environmental charges and taxes on, for example, acidifying
sulfur and nitrogen oxides, as well as on climate-warming carbon dioxide,
are used as one of the policy instruments for bringing about environmental
improvements. Such economic instruments are now being adopted to an increasing
extent internationally—a trend that will benefit the Swedish forest products
industry.
Legislation concerning packaging, waste paper, and waste
A few years ago, packaging based on new fiber appeared to be seriously threatened
by planned legislation within the EU in particular. Waste paper and various waste
paper systems have been favored legislatively. The negative consequences have
not materialized, however, since the legislation has become less radical and
adjustments have been made in the marketplace. AssiDomän has increased its
usage of waste paper where this has proved economically and environmentally
feasible. The drive toward increased standardization both in Europe and globally
entails both advantages and disadvantages. All things considered, however, this
trend is viewed more as an opportunity than as a threat.
Ecolabeling
The ecolabeling of sawn timber is viewed by AssiDomän as economically
advantageous since most of AssiDomän’s forestry operations have been
FSC-certified. There is still very little ecolabeling of packaging, compared with

consumer goods. Ecolabeling is not expected to affect profitability.
Additional Costs, Additional Revenues, and Goodwill
The annual additional costs for environmental investments and other
environmental measures that AssiDomän undertakes as strategic, voluntary
investments are estimated at MSEK 120–130. The life of these investments can
vary widely, however, since the additional values to which they give rise sometimes
have a short duration (environmental promotion, ecolabeling) of one or two years.
Forest certification, corporate image, trademarks, and customer alliances are
examples of goodwill investments with considerably longer lives.
Industry Comparisons
AssiDomän compares favorably with its Nordic competitors in environmental
concerns, particularly with regard to forestry practices and the introduction of EMS.
The generally high level of environmental compatibility in Nordic companies gives
the Swedish forest product industry a lead over many international competitors in,
E-54 Environmental Economics
for example, North America, who face considerable environmental investments in
the years to come.
Two important aspects of the economics of process engineering are environmental
ecolabeling and environmental LCA, which will be discussed below. People in these
industries frequently shorten these terms to “ecolabeling” and “LCA.” LCA is a
significant term in the operation of machinery as well; in that sense it will be
discussed later in this book (under the “L” entries), as the technical definition is
different when dealing with high-speed rotating machinery (versus forestry). The
two usages of the term should not be confused.
Reference and Additional Reading
1. Soares, C. M., Environmental Technology and Economics: Sustainable Development in Industry,
Butterworth-Heinemann, 1999.
Environmental Ecolabeling*
The purpose of ecolabeling is to distinguish products that have the least
environmental impact. The criteria for ecolabeling are regularly tightened to

stimulate the development of increasingly environmentally sound products.
Criteria are based on the total environmental impact of the product throughout its
life cycle. Requirements are also made on the function and performance of the
product.
There are several types of ecolabeling, all of which are the object of
standardization within the ISO, the International Organization for Standardization.
AssiDomän is participating in the Swedish standardization work by offering
viewpoints on the formulation of standards.
Within the Nordic Swan ecolabeling system, criteria are developed for packaging
paper and sawn timber products. Representatives of AssiDomän are participating
in this work. This type of labeling consists of a symbol intended to guide the
consumer in making environmentally informed purchases.
Environmental product declaration is another type of ecolabeling where a number
of environmental parameters are declared, but without being evaluated. The
primary target group is large purchasers within industry and government. The need
for environmental product declarations has increased with the introduction of EMS,
which require environmental information from suppliers and contractors. See Table
F-4.
Environmental Life-Cycle Assessment*
LCA is a method for describing the total environmental impact caused by a product
“from cradle to grave,” i.e., from extraction of the raw materials to final waste
disposal. See Fig. E-43.
After the scope of the assessment has been defined, environmental data are
gathered from all links in the production chain. This phase is called the inventory
and results in a body of data regarding resource and energy use, emissions to air
and water, and waste. Based on the collected data, an evaluation can then be made
of total environmental impact. This is called environmental impact assessment. LCA
Environmental Economics E-55
*Source: AssiDomän, Sweden. Adapted with permission.
is used as a guide to the prioritization of remedial measures. The method is also

used in product development for comparing alternative materials from an
environmental point of view.
Evaporative Coolers (see Chillers; Coolers, Dairy)
Exhaust Stacks (see Stacks)
Exhausters, Centrifugal Gas*
Gas exhausters of the geared type have reduced overall dimensions, weights, and
high-performance specifications. (See Fig. E-44.)
Machines of this type are used in geothermal plants where the turbine inlet steam
has a high noncondensable gas content. See Table E-10 for a list of example
applications.
The choice of gas exhauster is dictated both by the noncondensable gas content
and the steam flow rate in the turbogenerator set.
This means that installing a centrifugal gas exhauster may prove economically
advantageous even for low percentages of gas if the steam flow rate is sufficiently
high. See Table E-11.
The main advantages offered by gas exhausters over alternative solutions are
excellent noncondensable gas extraction process efficiency and the high levels of
E-56 Evaporative Coolers
FIG. E-43 Environmental life-cycle assessment. (Source: AssiDomän.)
* Source: Ansaldo, Italy. Adapted with permission.
vacuum that can be achieved. This accounts for power savings of between 40 and
60 percent with respect to other technical solutions such as steam driven ejectors.
Centrifugal gas exhausters are designed to offer long term in-service reliability,
high performance, and simplicity of design.
These design goals have led to the development of centrifugal impellers milled
from a single piece, or welded together to form a single block, thus improving
resistance to stress and corrosion. Advanced three-dimensional wheels are used to
achieve efficiency figures close to the values that characterize axial compressors,
but with a reduced risk of fouling. Particular attention has been given to heat
exchange during interstage cooling, achieved by direct contact and dehumidification

of the cooled gas.
Expansion Joints*
Expansion joints have been installed on the outlet flange of gas turbine exhausts
since turbines were first used in applications other than to fly planes. An expansion
joint is required to isolate the delicately balanced turbine from the thermally
expanding and vibrating ductwork system.
Recent developments in turbine technology have put ever-increasing demands on
the expansion joint supplier to accommodate more and more movements at higher
temperatures.
Though financial consideration is always a factor, reliability and trouble-
Expansion Joints E-57
FIG. E-44 Compressor set for Castelnuovo geothermal power plant (Italy). (Source: Ansaldo.)
* Source: Townson Expansion Joints, UK.
free service are the ultimate goals of both the end user and expansion joint
supplier.
Unfortunately the most competitively priced product does not guarantee these
goals. Expansion joints are an integral part of the exhaust system whose reliability
is every bit as important as the turbine itself. If the expansion joint fails then the
whole system must be shut down.
Basic Definitions and Configurations
Expansion joint suppliers have individual designs that they have developed and
tested over many years. These designs may vary from one supplier to another but
generally there are three basic configurations of expansion joints as seen in Figs.
E-45A, E-45B, and E-45C:
᭿
Hot to hot
᭿
Hot to cold
᭿
Cold to cold

Although designs may vary slightly there are basic principles that must be followed
to ensure a trouble-free life for the expansion joint. For example, to avoid
differential thermal expansion at the connecting flanges, both flanges must be made
E-58 Expansion Joints
TABLE
E-11 One OEM’s Sample Applications List—Significant Installations
No. Inlet
of Compr. Type Press Press Speed Power (kW)
Customer Plant Country Units Year Fluid Handl Capacity (bar) Ratio (rpm) Drive (1)
Acrylonitrile Plant
Tecnimont—Milano 1 1991 Centrifugal 67,000Nm3/h 0.98 3.34 4,700 4,360
Saratov (URSS) Air ST, EMG
Geothermal Power Station
ENEL—Roma 5 1989 Gas exhauster 20,000kg/h 0.07 15.71 5,300 2,430
Pisa (Italy) End. gas (2) ST
Bacon Manito 2 1991 Gas exhauster 10,500kg/h 0.14 7.47 6,800 870
Philippines End. gas (2) ST
ENEL—Roma 3 1993 Gas exhauster 4,000kg/h 0.07 15.71 9,070/ 565
Pisa (Italy) End. gas (2) 16,440/ ST
16,440
Nitric Acid Plant
UHDE-Dortmund for Quimigal 2 1980 Axial-centrifugal 63,400Nm3/h 0.99 6.06 6,950 5,660
Alverca & Lavradio (Portugal) Air ST, GE
Kemira Helsinki 1 1989 Gas expander 47,755Nm3/h 3.20 7,500 1,950
Refinery Service
Mannesmann-Germany for 1 1989 Centrifugal 16,952kg/h 6.48 1.59 11,252 1,100
Szazhalombatta (Hungary) Hydrogen EMG
Sugar Mill
I.S.I.—Padova 2 1986 Centrifugal 106,630kg/h 2.32 1.20 5,840 1,370
Finale E Pontelongo (Italy) Steam ST

I.S.I.—Padova 2 1987 Centrifugal 116,000kg/h 2.87 1.20 5,400 1,700
Argelato (Italy) Steam ST
Sadam S.p.A.—Fermo 1 1988 Centrifugal 116,000kg/h 2.35 1.41 6,800 2,660
Jesi (Italy) Steam ST
Terephtalic Acid Process
Snam P. for Enichem Fibre 1 1986 Gas expander 30,500Nm3/h 21.50 7,500 2,450
Ottana (Italy)
(1) EM = electric motor. (2) End. gas = mixture of CO
2
, H
2
S, steam.
EMG = electric motor with gear system; GE = gas expander; ST = steam turbine.
SOURCE: Ansaldo.
of the same material and have internal and external insulation designed to allow
both flanges to operate at the same temperature.
Design Principles
Composition
Fabric expansion joints are designed to accommodate the thermal movements and
vibration of turbines and adjacent ductwork without imposing any loads on the
Expansion Joints E-59
FIG.
E-45A Expansion joint: hot to hot. (Source: Townson Expansion Joints.)
FIG.
E-45B Expansion joint: hot to cold. (Source: Townson Expansion Joints.)
FIG. E-45C Expansion joint: cold to cold. (Source: Townson Expansion Joints.)
turbine outlet flange. This is achieved by utilizing a flexible element capable of
withstanding the high temperature and pressure fluctuations yet able to be
compressed or stretched without allowing the exhaust gas to escape.
The composition of a flexible element varies according to the individual supplier’s

recommendation but each will contain an impervious gas barrier at some point
within the structure. This gas barrier is usually made from a layer of PTFE or
similiar that would have an operational temperature limitation of around 250°C.
The inner layers of the joint are designed to reduce the exhaust gas temperature,
which can be as high as 650°C to within the temperature limitations of the gas
barrier.
Generally expansion joint flexible elements have a buildup of:
᭿
Outer cover—Weather and mechanical damage barrier
᭿
Gas barrier—Impervious layer of usually PTFE
᭿
Thermal barrier—Layers of fabric or insulation. The thickness and composition
of these will depend on the individual supplier and thermal drop required.
The flexible element of GT expansion joints should be designed to withstand the
full gas temperature without the aide of an insulation pillow. However it is common
practice to install a full-cavity insulation pillow for the following reasons:
᭿
Prevents fluttering of flexible element
᭿
Reduces noise emission through joint
᭿
Provides additional thermal insulation to expansion joint.
Advantages of fabric expansion joints over metallic joints
᭿
Accommodate more thermal movement within a shorter length.
᭿
Easy to replace for future maintenance.
᭿
Absorb radial growth without damage.

᭿
Accommodate lateral movements within a single joint.
᭿
Reduce imposed loads on turbine nozzle.
Problems and Solutions
Support frame damage
Cracking.
Gas turbine exhaust systems are subject to severe temperature
fluctuations ranging from ambient to full exhaust temperature within seconds. This
feature creates problems for the steel work of the exhaust system and the mounting
frame of the expansion joint. See Fig. E-45A. The inside surface of the frame sees
the full gas temperature almost instantly yet the outer flange that the joint is
mounted on is at this instant cold. This particular frame configuration has been
used successfully for many years on conventional coal-fired stations where there is
a startup period that allows all steel parts to reach optimum gas temperature over
a period of hours rather than seconds.
The upstand of the frame in Fig. E-45A is designed to position the flexible element
away from the full gas temperature so that it can survive without burning out.
Obviously the higher the upstand the cooler the temperature and the safer the joint
becomes, but in doing this you create greater temperature differentials between the
hot inner surface and mounting surface of the expansion joint. This is a delicate
balance that is one of the main secrets to a successful expansion joint, keep the
E-60 Expansion Joints
joint cold and risk cracking to the frame or keep the frame hot and risk burning
the joint out. The cracking of frames is more of a problem in rectangular expansion
joints than circular ones and becomes more of a problem as the size increases.
As a result of the temperature differentials the frame distorts by bowing inward.
(See Fig. E-46.) The result is flexing of the frames at the corners, which over a short
period of time causes cracking. Upstands vary depending on the designer but are
frequently seen to be between 100–150 mm, which is sufficient to cause cracking if

precautions are not taken. With finite-element calculations and on-site temperature
experience we have developed features within the corner design that eliminates the
cracking.
For example, all welds that are a potential source of cracking have been removed,
internal surfaces radiused, and corners stiffened to produce a design that can
withstand several thousand cycles.
Distortion. The deflecting of the straight lengths of the expansion joint frame
coupled with temperature differentials and induced stresses as a result of welding
can cause the internal sleeves to distort, which as a result may cause them to clash
or even fall off.
The internal sleeves are a vital component for the successful operation of the
joint, the loss of which could result in premature failure of the joint. The simplest
internal sleeve design is to weld a flat plate to the side wall of the expansion joint
frame. See Fig. E-45A. This is a design that has been operating successfully for
many years on conventional coal-fired power plants and smaller GT joints. However
as turbines increased in size it became apparent that this basic design needed to
be improved. To allow the sleeve to flex with the frame it should be supplied in short
lengths of approximately 1 to 1.5 m with a gap between each piece. This gap must
have a cover strip over it to prevent loss of pillow. To eliminate distortion as a result
of welding and to stiffen the sleeve, it is suggested that the sleeve be flanged and
bolted to the side wall. See Fig. E-47.
Tests and field experience have shown that internal sleeves should not be
manufactured too long as this would allow them to vibrate which could cause
them to fall off. Sleeves over 250 mm must be given special consideration.
Heat damage
Lateral movements.
As turbines, boilers, and associated ductwork get ever bigger,
the thermal movements increase proportionally. However, due to financial
Expansion Joints E-61
FIG.

E-46 Cracking in an expansion joint. (Source: Townson Expansion Joints.)
restraints the number of expansion joints in each system has not increased; it is
merely expected that the same number of joints will accommodate the increased
movements. There comes a time, though, when a simple expansion joint cannot
absorb any more movement individually. This is especially true when one considers
lateral movements.
Typically at the HRSG inlet the expansion joint sees the vertical growth of the
boiler, which can be as much as 150 to 200 mm. Inexperienced suppliers would try
to use one single expansion joint for this application but in fact no individual flexible
element should be asked at these elevated temperatures to absorb more than 60–
75-mm lateral movement. The materials of the expansion joint start to crease or
fold in the vertical side walls as the joint absorbs the lateral movement. As the folds
become more and more pronounced the external materials of the joint are prevented
from being cooled by the ambient air, heat builds up, and the joint fails prematurely.
The solution to the problem is to simply limit the lateral movement on the
individual joint by:
᭿
Presetting the joint by half the lateral movement.
᭿
Installing a double joint with a pantograph control mechanism to equally divide
the movement between both joints. See Fig. E-48.
E-62 Expansion Joints
FIG.
E-47 Support frame distortion. (Source: Townson Expansion Joints.)
FIG.
E-48 Pantograph design. (Source: Townson Expansion Joints.)
Axial movement. Axial thermal movement can create different problems for the
expansion joint than those seen with lateral movements. Conventional flat belt
expansion joints when installed have small creases or folds in the corner areas.
Under normal operational and small axial movements these creases do not cause

a problem but as movements increase the creases become so pronounced that the
outside materials are not allowed to cool and therefore burn out. To prevent this
from happening the joint should be constructed with a preformed arch in the
corners. See Fig. E-49. This configuration will increase the movement capacity of
the fabric joint to approximately 150 mm; anything above this would require a
double joint using a pantograph mechanism. Excessive axial movements can also
result in the material of the joint in the straight lengths folding either back on itself
or over the backing bar. Either situation would cause premature failure of the joint.
Mounting flanges. The flange frame on which the joint is mounted is designed to
operate at very high temperatures as described previously to reduce stress levels.
Unfortunately these temperatures frequently cause failure of the expansion joint
if they have not been considered by the expansion joint designer. See Fig. E-50.
Expansion Joints E-63
FIG. E-49 Flat belt (a) and preformed arch (b) construction. (Source: Townson Expansion Joints.)
FIG.
E-50 Heat damage at mounting flange. (Source: Townson Expansion Joints.)
(a)
(b)
The temperature of the frame is transferred through the mounting bolt to the
backing bar that burns the joint from the outside or allows heat to build up at point
A resulting in premature failure of the joint.
Generally at gas temperatures of 400 to 500°C conventional expansion joints
operate successfully without the need for any special precautions. For temperatures
above these the overall design configuration should be reviewed by finite-element
analysis to establish the temperature of the backing bars.
Should the backing bar temperature be a problem it can be reduced by installing
a gasket under the joint and using thermal barrier washers.
Proximity of buildings. Fabric expansion joints are designed to withstand the full
gas temperature but for them to achieve this there must be a relatively cool ambient
temperature of less than 100°C. The design of the fabric element is such that the

gas temperature is lowered through the different layers of the joint to an acceptable
level at the point where the gas barrier is located within the joint. Frequently joints
are located within the acoustic enclosure where the ambient temperature can be
higher than expected, which can result in an abnormal temperature rise through
the joint and premature failure.
High ambient temperatures are a real problem for expansion joint designers.
Materials to overcome the problem by providing a gas barrier that will operate at
elevated temperatures are limited to the likes of stainless steel foils. Unfortunately
foils do not absorb movements easily and are prone to cracking from vibration. The
recommended way to solve this problem, providing the ambient temperature can-
not be reduced, is to blow cooling air over the joint surface. The cooler the outside
surface of the joint the greater the life expectancy. Problems of this nature also
occur when joints located close to buildings or the floor do not allow adequate room
around the joint for air circulation. The closer a structure gets to the outer surface
of the joint the greater the insulating effect it has on the joint surface.
Water washing
Expansion joints are designed to withstand hot gases and thermal movements; they
are generally not designed to withstand the moisture that would build up in the
joint from water washing the ductwork or turbine. The effect of this is twofold. First,
the moisture attacks the fiberglass or high temperature fabric layers to a point that
when they are dry they will have lost a considerable amount of their tensile strength
and the integrity of the joint will be reduced. Second, the water wash often contains
solvents to enhance the washing effect. These solvents settle in the base of the joint
and once the water has vaporized a film remains within the fabrics or on the PTFE
gas barrier. These solvents have in the past caught fire at startup, which completely
destroys the joint. Various materials are available to line the inside face of the joint
to prevent moisture attack, but unfortunately water will eventually get through.
The ideal solution to this problem is to prevent the water access to the joint rather
than trying to accommodate the moisture within the joint. See Fig. E-51.
Radial growth of steel parts

The expansion joint designer has many factors to consider when selecting
materials, configurations, and methods of manufacture. One condition that is often
overlooked is the fact that the steel frame that the joint is mounted on expands
radially at the same rate as it does axially. For example a stainless steel frame with
internal duct dimensions of 5 m ¥ 5 m operating at 550°C would expand radially
50 mm, which in effect is stretching the materials of the joint by this amount. To
E-64 Expansion Joints
overcome this problem reputable suppliers manufacture the joints using materials
cut on a bias (see Fig. E-52), which allows the individual layers to stretch by as
much as 15 percent more than materials cut the conventional way.
Insulation pillows
Pillow loss.
Turbine exhaust gases operate at such a high velocity that they can
create a negative pressure or sucking effect within the expansion joint. The joint
and steel work are designed to withstand this but the insulation pillows need special
attention. The velocity of the gas attacks the very fibers of the pillow and sucks
them downstream in what is known as a picking effect. This is a slow process that
gradually works at the pillow until the whole pillow has disappeared. There have
been instances when the pillow as a complete unit has been sucked downstream
through the gap in the sleeves. To prevent this the pillows must be mechanically
fixed to either the side wall of the frames or the surface of the sleeves. Care must
be taken to allow adequate material between the fixings to accommodate the
thermal movement. Second, the pillow should be encased in a fine wire mesh to
prevent the picking effect. High nickel alloy meshes are available that will prevent
small particles passing through. Though not always possible due to movement
limitations, utilizing a floating sleeve design (see Fig. E-53) helps to overcome the
picking effect.
Pillow settlement. Insulation pillows are produced from insulation blankets, which
in turn are manufactured from small strands of either ceramic fiber or fiberglass.
Explosion; Explosion Hazard Analysis; Explosion Hazards E-65

FIG.
E-51 Water washing. (Source: Townson Expansion Joints.)
FIG.
E-52 Straight and bias cuts. (Source: Townson Expansion Joints.)
Though the density of the material is of the order of more than 150 kg/m, the
material itself is still quite loose. Expansion joints vertically mounted are always
at risk of having the insulation pillows in the vertical legs settle down to the bottom
of the leg exposing the top corners of the joint.
Pillows must be manufactured incorporating cushion pins equally spaced across
the pillow to keep the layers of insulation bound together. In addition pillows should
be either pinned to the side walls or sleeves as described above or flanged so
they can be mounted between the expansion joint and mounting steelworks. See
Fig. E-54.
External insulation
Expansion joint manufacturers worldwide insist that the outside of gas turbine
expansion joints must not be insulated over. As described previously, covering the
joint would significantly raise the ambient air temperature and cause premature
failure of the joint. The external insulation should be terminated at the joint as
shown in Fig. E-54. Failure to do this could jeopardize the finite-element calculation
that guarantees the required life cycle of the frames or could cause premature
failure of the joint as a result of heat buildup from exposure of the steel casing.
Noise
Noise requirements must be specified at the inquiry stage as they can significantly
affect the design of the fabric element and steelwork. To achieve optimum noise
reduction the joint and pillow must be manufactured from the highest density
material available that will operate at the stated design conditions. The internal
E-66 Expansion Joints
FIG.
E-53 Floating sleeve. (Source: Townson Expansion Joints.)
FIG.

E-54 External insulation. (Source: Townson Expansion Joints.)
flow plates should be designed slightly different to reduce the gaps allowed for
thermal movement. Floating sleeves are often recommended in this situation. See
Fig. E-53. Noise calculations should be made available by the expansion joint
supplier.
Nonmetallic expansion joints, if designed and installed correctly, will provide
years of trouble-free service. One of the most common reasons for failure in
expansion joints are problems developing within the expansion joint as a result of
incorrect installation or damage caused during installation. Emphasis must be
placed on strictly following the guidelines as laid down in the installation manual
supplied with the joints. These instructions have been developed over many years
of experience of fitting joints and solving problems. To ignore them or deviate is
risking failure of the joint.
In conclusion, nonmetallic expansion joints are the most economical method of
accommodating thermal expansion in gas turbine and HRSG applications. However,
to achieve this the expansion joint supplier must have a proven track record as
most of the above have been developed over many years using finite-element
calculations, on-site experience, and exposure to problems and providing expansion
joints that have stood the test of time.
Explosion; Explosion Hazard Analysis; Explosion Hazards
Explosion hazards are a major consideration in most operating plants. Hazards
include leaks of flammable liquid and/or a gas. One potential culprit is gas-turbine
fuel. Others may be hydrocarbon product leaks. Because of space considerations,
analyzing gas-turbine fuel leaks as a hazard will be discussed as a typical case.
Although the extracts that follow are from powerplant operators, their methodology
with their gas turbine or combined cycle applications are not restricted to power
production applications.
Case Study 1: Assessing Explosion Risk Potential at Teesside Power Station, UK*
The potential for an explosion inside a gas turbine combined heat and power (CHP)
plant or a combined cycle gas turbine (CCGT) plant enclosure from a fuel leak has

been widely addressed in the industry and reviewed at a number of seminars.
Enron, the Teesside Power Station operators, contracted a study into the explosion
potential inside the gas turbine (GT) enclosure and to recommend solutions to
achieve an acceptable level of risk.
A structured approach was applied to identify the hazard, evaluate the risk, and
identify effective, practical, risk reduction measures.
The study consisted of:
᭿
A comprehensive air movement study inside the enclosure to define the total air
balance and to create a 3D air velocity grid.
᭿
A process hazard review (PHR) to identify credible leak events for the CCGT fuels.
᭿
Assessment of the potential for formation of a flammable mixture for each case.
᭿
Evaluation of potential ignition sources to review causes and to determine
suitable probability values to be used in the risk assessment.
Explosion; Explosion Hazard Analysis; Explosion Hazards E-67
*Source: Adapted from extracts from Hunt and Beanland, “A Risk Based Approach to the Potential for
CCGT Enclosure Explosions: A Study on Teesside Power Station,” Eutech Engineering Solutions Ltd.,
UK, ASME paper 98-GT-446.
᭿
A hazard analysis (HAZAN) to quantify the risk from an explosion to the
operator at most risk.
From the resulting fault trees the most effective options to achieve a measured
reduction in risk were identified. These included improved gas detection, air
circulation measures to reduce the incidence of leaks, revised CCGT enclosure
access, and operating procedures.
The structured assessment of the risk and the selection of effective improvements
as applied to the study on Teesside Power Station is covered below.

The plant
Teesside Power Station, with a 1875 MW output, is the world’s largest gas-fired
combined cycle heat and powerplant (see Fig. E-55). It has a total of eight
Westinghouse MW 701 DA gas turbines with associated heat recovery generation
and two Westinghouse 800 te/hr steam turbine generators. The combination
provides for low environmental emissions and high thermal efficiency. All eight
CCGT units are identical having acoustic enclosures for noise suppression with
ventilation for gas turbine cooling. See Table E-12.
Figure E-56 shows the station’s basic process flow diagram. From this diagram
it can be seen that there are a number of fuel sources available to ensure continuity
of process steam supply to the adjacent chemical companies. The primary fuel
source is natural gas supplied from either the Central Area Transmission System
(CATS) or Transco’s National Transmission System. Backup fuel is available in the
form of vaporized propane, which may be used to increase the natural gas Btu value
as a startup fuel prior to introduction of liquid fuel. Naphtha is also available for
online transfer to provide security of steam supply in the event of loss of primary
fuel.
E-68 Explosion; Explosion Hazard Analysis; Explosion Hazards
FIG. E-55 Teesside Power Station. (Source: Hunt and Beanland.)
The potential for an explosion from a fuel leak inside gas turbine enclosures for
CHP and CCGT plants had been identified, and during early 1996 Enron, the
operator, contracted Eutech to undertake a study into the risk to operators inside
the enclosure from the potential for an explosion from the gas fuel supply.
The study used a structured approach based on experience with carrying out
similar studies within the chemical/petrochemical industry to identify the hazards,
evaluate the risk, and to identify practical risk reduction measures.
Unfortunately at 00:25 hr on July 17, 1996, a fire and explosion occurred in CCGT
106 enclosure. The incident was due to ignition of a leak of naphtha from a joint
during fuel changeover. The explosion injured an operator who had entered the GT
enclosure to confirm satisfactory operation of equipment and it caused serious

Explosion; Explosion Hazard Analysis; Explosion Hazards E-69
TABLE E-12 Teesside Power Station CCGT Leak Scenarios
Leak Event Cases Orifice Size (mm) Mass Rates (kg/sec) Mixture Formed
Small (<1.5 mm dia)
1 Leak through valve stem 1.1 0.005 Nonflammable
Medium (1.5 to 6 mm dia)
2 Joint with no gasket 2.8 0.013 Flammable
Large (>6 mm dia)
3 0.25≤ pipe failure 9.2 0.14 Flammable
4 Untested flange 10.2 0.18 Flammable
5 0.50≤ pipe failure 15.8 0.42 Flammable
6 Misalligned joint 17.1 0.52 Flammable
FIG. E-56 Teesside Power Station process flow diagram. (Source: Hunt and Beanland.)