Process Engineering Equipment Handbook Episode 2 Part 5 pps

are easily dropped and lost. For example, a 60-in ID vessel made by this information
source has only 20 removable parts (not counting the filter cartridges) as opposed
to 235 parts in a conventional design.
There are no support arm threads to become stripped, and no support arms. This
avoids the difficult job of removing a collapsed filter cartridge from a support arm.
The design of the retainer assembly allows all maintenance work to be done
through a small closure (below), with substantial savings in first cost as well as in
man-hours in removing and resealing the closure.
Gas filters are designed for both operating efficiency and clean-out efficiency. To
make the cartridge replacing operation as quick and simple as possible, a quick-
demountable filter cartridge retainer assembly is used in all vessels of 30-in shell
diameter and larger. The result is a substantial saving in both man-hours and
down-time whenever cartridges are replaced.
Not all foreign matter from the gas stream is deposited on the filter cartridges.
In any gas filter there is a gradual buildup of rust, scale, and other gas line dirt on
the inner surfaces of the shell, especially at the bottom.
This phenomenon is used by directing the incoming gas into a generously sized
inlet chamber (① in Fig. F-13), where the abrupt drop in velocity allows the heavier
particles to fall out of the gas stream by gravity before they reach the filter
cartridges. Thus the filter cartridges’ dirt-holding capacity is used to best advantage
in trapping the hard-to-catch fine particles.
The material collected in the shell is removed from gas filters. There are no
longitudinal support arms for the filter cartridges, so that when the cartridges are
removed, the filter chamber (② in Fig. F-13) is empty of all structural parts. The
standpipes that connect to the cartridge outlets are arranged in a square rather
than a diagonal pattern, with plenty of room between them for dirt to fall through
to the bottom of the shell. In addition, the cartridges and standpipes are positioned
well above the bottom, clear of accumulated dirt.
Because of the design of the cartridge retainer assembly and location of the
cartridges themselves, all of this servicing can be done by one person, standing

outside the vessel.
Sizing and performance
For this original equipment manufacturer’s (OEM) product range, for instance,
series MT multitube filters are built in sizes from 6-in through 144-in shell diameter.
They are usually selected for a pressure drop of
1
/
4
to 2 psi (clean), although they
can be selected or designed for other pressure drops.
Filters F-9
FIG. F-13 Series MT horizontal multitube filter. (Source: Peerless.)
Multitube filters remove 100 percent of all particles larger than 3 microns in
diameter and 99
1
/
2
percent of all particles
1
/
2
to 3 microns.
Construction
Each filter cartridge consists of a small-diameter tube made up of closely packed
glass fibers and covered with a knitted cotton sock. A perforated metal liner stiffens
the cartridge and maintains its inside diameter against the inward-acting pressure
of the gas.
The shell is constructed in accordance with the latest edition of the ASME Code—
with stamp. A resident National Board licensed inspector is on hand at all times to
check each phase of construction.

Optional features
Customized construction can be provided to meet various state codes and customer
specifications. An external bypass with rupture disc can be added. A davit can be
installed to facilitate removing the closure head. Alternative metals can be used
instead of the standard carbon steel.
In-line Gas Filters*
In-line gas filters (see Fig. F-14) generally provide the same gas-handling
performance as (series MT for this information source) multitube filters. They are
built in two configurations—vertical (VGF) and horizontal (HGF). (VGF and HGF
are both model designations specific to this manufacturer.)
The inlet and outlet nozzles are opposite each other, on a common centerline,
near one end of the vessel. This arrangement simplifies connections and allows
installation in piping runs that are too short for other filter designs.
Sizing and performance
VGF and HGF filters are built in sizes from 6-in through 24-in shell diameter. They
are usually selected for a pressure drop of
1
/
4
to 2 psi (clean). Like the MT filters,
they are guaranteed to remove 100 percent of all particles larger than 3 microns
diameter and 99
1
/
2
percent of all particles
1
/
2
to 3 microns.

Construction
Each filter cartridge is made up of closely packed glass fibers covered with a knitted
cotton sock. The cartridge is stiffened by a perforated metal liner. It is held in place
by a longitudinal rod and wingnut.
The shell is ASME Code stamped, as in the series MT. The O-ring closure allows
quick access to the interior.
Optional features
A davit can be installed to facilitate removing the closure head. A mounting base
(cylindrical in the VGF, angle iron in the HGF) can be added.
F-10 Filters
*Source: Peerless, USA. Adapted with permission.
FIG
. F-14 In-line gas filter. (Source: Peerless.)
F-11
Flare Stacks (see also Stacks)
A flare stack is a stack that conducts vented gases that are then lit at its top exit
by a burner and ignition system (which has its own fuel supply line). The stack has
to be a minimum distance (worked out as a function of substances being flared and
their heat-release rates) from the rest of the plant for the purpose of preventing
fires, ignition, and secondary damage to other equipment such as storage tanks.
Floating Covers
In the petrochemical and chemical industries, evaporation losses from stored liquid
product can be sizable and costly. When these products are stored in tanks, they
can be covered with a movable floating cover that will eliminate evaporation. Tank
manufacturers can supply suitable covers for the application in question (see Tanks).
Fluidized Bed
In a large-scale reaction process, a catalyst is often used to assist the reaction. To
maximize catalyst surface area, the catalyst may be pulverized and then held in
suspension (fluid suspension or fluidized bed). See Reactors.
Forest Products

These products form part of the agricultural sector in that they require that good
agricultural practices, such as selective log felling and timely seedling planting, be
followed so that the raw material resource can be sustained. The forest products
industry is also in a position to inadvertently or otherwise affect many other
industries and quality-of-life factors. For instance, it has been determined that the
damage done to much of the Canadian west coast salmon stock was a result of high
levels of lumber mill sawdust that clogged salmon spawning grounds.
Deforestation that occurs if logging is not done selectively has severe
consequences, including loss of wildlife habitat (see Ecosystem) with consequential
loss of revenue for personnel who work in these areas and soil erosion. It is widely
accepted that had severe deforestation occurred in the rain forest around the
Panama Canal, the canal would have been irretrievably clogged with eroded soil
soon after.
The forest products industry, therefore, is an industry that could be thoroughly
interwoven into the community in which it is located. As an illustration, the following
extracts adapted from the 1997 AssiDomän company report regarding its corporate
environmental objectives are included here. Further understanding of this material
is evident by reading the sections on Environmental Economics and Pulp and Paper;
and the total material summaries, the material on the contemporary forest and
timber industry, and the packaging materials production data in this section.
Contemporary Forest and Timber Industry Practices*
In many countries of the world, the forest products industries carry on as before,
with developers hastily cutting, clearing, and burning down forest to make their
F-12 Flare Stacks
*Source: AssiDomän, Sweden. Adapted with permission.
products. This form of production is not sustainable. In the United States and
Canada, consumption of forest materials in industry is still high compared to the
western European countries that aim at maximizing the output from forest
products, thereby minimizing their use and maintaining other practices that help
ensure their raw material supply will be sustainable.

Case study 1: Forestry management at AssiDomän
This case describes typical, sophisticated, state-of-the-art western European
management of the raw materials required for forest products. See also Tables F-
2 and F-4 through F-6 and Figs. F-15 through F-17. Note that measures involving
emissions reduction take on considerably more significance in a country with NO
x
and SO
x
taxes (like Sweden).
Forestry work
᭿
All forest management regions work in accordance with the Environmental
Management System (EMS) standard ISO 14001. This means that they have
established a local environmental policy as well as goals and programs for their
environmental work. EMS registration was not possible for forestry until 1997,
so work is currently focused on ISO 14001.
᭿
The forest management regions in Kalix, Älvsbyn, Lycksele, Örebro, and
Värnamo were approved for certification in accordance with ISO 14001. See Fig.
F-16.
᭿
The two timber units started work with the introduction of EMS.
᭿
More than half of AssiDomän’s productive forest land area, 1.7 million hectares,
was approved during 1997 in accordance with the Forest Stewardship Council’s
(FSC) Swedish standard for certification of forestry.
᭿
Ecological landscape plans will be drafted for the entire forest holdings by
2002.
Forest Products F-13

FIG. F-15 AssiDomän operations regions in Sweden. (Source: AssiDomän.)
᭿
New directions for precommercial thinning were put into use during the year.
Regeneration planning prior to final felling was finished in time for the 1998 field
season.
᭿
This source imported 11 percent of the pulp and paper industry’s wood needs in
the form of roundwood and chips during 1997. The imported wood comes mainly
from the Baltic states and otherwise from Finland, Russia, Germany, and Brazil.
F-14 Forest Products
TABLE
F-2 Activities on Corporate Environmental Objectives
Corporate Environmental
Objectives 1997 Outcome Further Work
To certify the Group’s forest More than half of the forest holdings The remaining forest holdings are expected
holdings in accordance with were certified during the year. to obtain certification during the first half
FSC’s standard during 1997. of 1998.
That all units will have begun Approx. 90% of the units have begun Some 15 units are expected to be certified in
the work on introducing EMS this work. Some 15 units were 1998 and the remainder in 1999 and 2000.
by year-end 1997. approved for certification according
to ISO 14001 and/or EMAS
registration.
To implement cost-effective Life-cycle assessments are an important The environmental objective remains. The
environmental measures based part of the environmental work and Group’s environmental work will be
on life-cycle assessments. have been used in product pursued in a holistic perspective.
development and in choice of
transport mode.
To achieve ecocycle compatibility An “ash restoration group” has been Field studies and development projects
in the Group’s operations. Ash formed to promote the recycling continue.
restoration in large-scale tests. of ashes and residual products to the

forest. A field study has been started.
To reduce the use of fossil fuels, The environmental objective was not The environmental objective remains. As a
mainly at the Group’s pulp achieved at most mills in 1997. At result of modernizations and other strategic
and paper mills. some mills use has increased as a investments in energy and recovery
result of production increases and systems in the mills, the use of fossil fuels
higher prices for biofuels than oil is expected to decline progressively up to
(due to national energy tax policy) the turn of the century. A black liquor
and rebuilding work in the plants. gasification plant is being designed at
The biofuel boiler at AssiDomän Frövi AssiDomän Kraftliner. This will yield
was rebuilt, permitting increased higher energy efficiency and increase
biofuel use. Energy-saving measures electricity production from biofuel.
have been implemented at AssiDomän
Skärblacka so that oil use will be
reduced by 9000 m
3
per year.
To collaborate with carriers in Collaboration with carriers in transport The environmental objective remains. Work is
projects aimed at greater of both timber and finished products. being pursued in prioritized areas.
environmental compatibility Reduced specific transport volume has
and shorter transport distances. been achieved by scheduled route
transport. Environmental
questionnaires are used to evaluate
carriers. Environmental calculations
comprise part of the basis for choice
of transport mode.
To promote the development of Several new packaging solutions with Working toward the environmental objective
lighter weight and more common environmental profiles were is integrated in the daily work of
resource-efficient packaging developed during the year. Reduced developing new products.
materials and packaging. packaging weight is an important
factor in this work.

To participate in and carry to AssiDomän has been represented in the AssiDomän will actively participate in
completion the joint sectoral management of the project, which continued activities within the sector’s
environmental research project will be concluded in 1998. environmental research.
within SSVL.
SOURCE: AssiDomän.
Forest Products F-15
TABLE
F-3 Production Data on Barrier Coating
1997 1996
Per Tonne Per Tonne
Total End Product Total End Product
Paper raw material, tonnes/kg 131,700 881 110,400 870
Plastic, tonnes/kg 26,800 179 25,500 200
Fossil fuels, TJ/GJ 108 0.7 120 0.9
Purchased electricity, 44 0.30 32 0.25
GWh/MWh
SO
2
, tonnes/kg
1
1 0.007 1 0.006
NO
x
, tonnes/kg
1
19 0.13 9 0.07
Production of plastic-coated 149,500 127,000
paper, tonnes
By-products to recycling, tonnes 5,450 8,850
1. Estimated values.

TABLE F-4 Total Material Summary of AssiDomän Operations: Forest Management Regions
(8 Units)
1997 1996
Raw material use
Harvested own forest, excl. standing timber, 1000 sm
3
ub 6,190 5,930
of which harvested with own machinery, 1000 sm
3
ub 3,600 3,760
of which harvested by contractors, 1000 sm
3
ub 2,590 2,170
Purchased forest, 1000 sm
3
ub 1,160 980
of which harvested with own machinery, 1000 sm
3
ub 120 50
of which harvested by contractors, 1000 sm
3
ub 1,040 930
Total wood raw material, 1000 sm
3
ub 7,350 6,910
Oils, m
3
730 625
of which vegetable, m
3

240 ND
Fertilizer, tonnes N 360 350
Energy use
Total fossil fuels, own machinery, TJ 245 445
3
Emissions to air
1
SO
2
, tonnes 0.2 0.7
NO
x
, tonnes 320 615
CO
2
fossil, tonnes 18,100 33,200
Waste
Hazardous waste, m
3 2
156 145
Recovered spent oil, % 32 23
Land
Total land area, 1000 ha 4,49
4
4,430
Productive forestland, 1000 ha 3,280 3,320
Cultivated forestland, 1000 ha 3,030
5
3,090
Finally felled area, ha 26,800 28,700

Products
Wood to AssiDomän, 1000 m
3
fub 5,020 3,690
Wood, sold externally, 1000 m
3
fub 2,330 3,220
Total wood delivered, 1000 m
3
fub 7,350 6,910
ND = No data available.
1. From own machines. 2. Collected oil. 3. Over available estimated values. 4. Incl. 123,000 ha not
inventoried previously. 5. Certain areas have been redefined in conjunction with ecological landscape planning.
Total
Total
Continued environmental work. All forest management regions and timber units
were certified according to ISO 14001 during the first half of 1998. At the same
time, AssiDomän’s entire holdings of productive forest land were FSC-certified.
With the introduction of EMS, each unit set up environmental objectives.
Examples of areas covered by the objectives are: reduced usage of fossil fuels,
improved waste management and resource management, and programs for the
preservation of biodiversity in the forest landscape.
The FSC certification affects AssiDomän’s forestry practices in a number of ways.
Some of the more important changes are the requirements on an increased
hardwood fraction and controlled burning on forest land, and the fact that more
deadwood should be left. Besides consideration for the environment, the FSC’s
criteria also include economic and social consideration. One example of the latter
is that consideration be given to reindeer herding.
Ecological balance sheet. For the purpose of evaluating how well the forest-related
objectives have been achieved, internal follow-up has been done since 1993 in the

F-16 Forest Products
TABLE
F-5 Total Material Summary of AssiDomän Operations: Sawmills and Wood
Processing (11 Units
1
)
1997 1996
Raw material use
Wood, 1000 sm
3
ub/sm
3
ub 2,380 2.2 2,090 2.1
Oils, m
3
/dm
3 2
233 0.21 200 0.20
Externally supplied energy
Fossil fuels, TJ/GJ 90 0.082 73 10.073
Purchased thermal energy, TJ/GJ
3
194 0.18 234 0.23
Purchased electricity, GWh/MWh 96 0.088 92 0.092
Emissions to air
4
SO
2
, tonnes/kg 33 0.030 37 0.037
NO

x
, tonnes/kg 179 0.16 142 0.14
Particles, tonnes/kg 78 0.071 95 0.095
CO
2
fossil, tonnes/kg 6,810 6.2 4,850 4.9
CO
2
biogenic, tonnes/kg 97,500 89 82,600 83
Residual products and waste
Hazardous waste, m
3
/dm
3 5
45 0.04 60 0.06
Landfilled material, m
3
/dm
3
16,000 15 24,000 24
Products
Sawn timber, 1000 m
3
1,100 1,000
By-products for external delivery
Sawdust, bark, chips, 1000 m
3
/m
3
1,210 1.1 1,020 1.0

Pulp chips, 1000 m
3
/m
3 6
2,050 1.9 1,820 1.8
Heat, GJ/MJ 7,100 6.4 1,200 1.2
1. Of which one unit was sold as per 31 March 1997 and one as per 31 December 1997. 2. Lubricating and
hydraulic oils. 3. Based on biofuels. 4. Only from own energy generation. 5. Collected oil and chemical residues.
6. Raw material for the pulp industry.
Total
Per m
3
Sawn
Timber
Total
Per m
3
Sawn
Timber
Forest Products F-17
TABLE
F-6 Total Material Summary of AssiDomän Operations:
Transport Activities
1997 1996
3
Transport volume
1
Road, mill. tonne-km 2,860 1,770
Sea, mill. tonne-km 5,230 4,800
Rail, mill. tonne-km 1,670 1,240

Total, mill. tonne-km 9,760 7,810
Energy use
Fossil fuels, TJ/MJ 3,420 0.35 2,330 0.30
Electricity, GWh/kWh 68 0.007 57 0.007
Emissions to air
SO
2
, tonnes/g 1,670 0.17 1,710 0.22
NO
x
, tonnes/g 3,630 0.37 3,610 0.47
CH, tonnes/g
2
225 0.023 185 0.024
CO
2
fossil, tonnes/g 254,000 26 181,000 23
1. Return trips only included for system traffic at sea. 2. Hydrocarbons.
Common key figure for transport emissions. 3. Excl. Central and Eastern
Europe.
Total
Per
tonne-
km
Per
tonne-
km
Total
form of an ecological balance sheet. The balance sheet is a good aid in the further
training of forestry workers. See also Figs. F-18 through F-22.

The grades for final felling show that the former trend of improvements from year
to year has been improved. This is true for site-adapted forestry as well as for nature
and water conservation. The number of evaluated categories, as well as the
requirements for getting the highest grade for the individual site, have gradually
increased as knowledge has grown and the criteria for FSC certification have taken
firmer shape. An example of a new category for the year 1997 was evaluation of
whether the nature conservation measures were concentrated and targeted
correctly within the felled site. Only 44 percent of the final felling area received the
highest grade in this respect. This is an important, but difficult, category that will
require further training.
On more than 16 percent of the evaluated sites, so many trees have been left on
the productive land that an appreciable portion of these trees are not judged to
contribute to better functional nature conservation. Here the production target was
disregarded, resulting in a lower yield.
The 1997 balance sheet showed that on 88 percent of the final-felled area, the
best possible combination of felling method, tree species, and regeneration method
were chosen.
The thinnings in the 1997 balance sheet showed no great changes in grades
compared with 1996. Water conservation improved slightly, however. The removal
of hardwood trees in the thinnings decreased since the introduction of the new
thinning instruction in 1996. However removals were still too high to meet the long-
range target of a 10 percent hardwood fraction of standing timber.
Precommercial thinning was included in the ecological balance sheet starting in
1998: It is important for tying together the follow-up of stand management during
the entire rotation period.
Approximately 14 percent of the productive forest land area is given special
treatment for nature conservation purposes in connection with both final felling and
thinning. This is a reasonable level for preserving and strengthening biodiversity.
Timber
The business area’s nine sawmills and wood-processing units are required to obtain

permits under the Environmental Protection Act.
The plants impact the environment mainly through emissions from biofuel
combustion, surface runoff from timber storage, noise from production and
transport, and waste management.
The sawmills produce by-products in the form of chips, sawdust, and bark. These
materials are used as raw materials in pulp and particleboard manufacture or as
biofuels, either at the sawmills or externally.
Environmental work list for a sample year (1997)
᭿
Environmental management systems were introduced at six of the nine units
during the year. The main reason why EMS have not yet been introduced at three
of the units is extensive restructuring of the operations.
F-18 Forest Products
FIG. F-16 Carbon dioxide balance. (Source: AssiDomän.)
Forest Products F-19
FIG. F-17 Sawmills and wood processing. (Source: AssiDomän.)
FIG. F-18 Nature conservation measures on AssiDomän’s productive forest land. (Source:
AssiDomän.)
᭿
Niab Hestra and Hasselfors Timber were certified in accordance with ISO 14001.
᭿
Environmental training was carried out for all employees at six units as a step
in the introduction of EMS.
᭿
Two units, Hasselfors Timber and Lövholmen, were certified during the year with
regard to “chain of custody” for production of sawn timber from raw material from
FSC-certified forestry. This means that the origin of the timber can be guaranteed
through the whole production chain.
᭿
Environmental incidents occurred at some of the units during the year. Examples

include exceeding prescribed noise level and improper handling of contaminated
industrial sites. The incidents were reported to the appropriate authority and
remedial plans were prepared and initiated.
᭿
Noise-suppression measures were adopted at three units.
᭿
Climate-controlled timber watering was installed at three units, leading to
reduced water consumption and thereby reduced surface water runoff.
᭿
Measures were adopted at four units to reduce emissions of nitrogen oxides and
particulates. For example, a new solid fuel boiler with cyclone ejector and
electrostatic filter was installed at one sawmill and a wet scrubber at another.
᭿
Waste management was improved by increased source separation at five of the
units.
Environmental work scheduled for a typical year (1998). In accordance with ISO 14001,
the units adopted environmental objectives for their operations. Examples of such
objectives are to reduce the quantity of spillage and waste, to reduce emissions from
combustion, to improve oil and fuel management, to adopt noise suppression
measures, and to reduce effluent discharges.
F-20 Forest Products
FIG. F-19 The evaluation of each final felling and thinning results in three different grades: site-adapted forestry (how well
the wood-producing capacity of the different growing sites is used), nature conservation, and water conservation. Grades
are awarded on a five-point scale, where 3 is satisfactory and 5 is the highest grade. (Source: AssiDomän.)
Packaging Materials
A closer look at the manufacture of two common packaging materials enables a
better understanding of the need for environmental policy to develop as an integral
part of increased design sophistication.
Barrier coating
There is a great need for fiber-based packaging with some kind of barrier against

moisture or grease. The environmental work within the business area is being
focused on the development of packaging solutions where new material
Forest Products F-21
FIG
. F-20 Seed and plants management. (Source: AssiDomän.)
combinations permit more efficient resource utilization and where the barrier
coating method is environmentally compatible. See Table F-3.
The environmental issues given top priority are:
᭿
Solvent-based inks, barrier chemicals, and adhesives. The possibilities of
replacing these with water-based products are being explored.
᭿
Waste and residual product management. The possibilities of utilizing reject
and production waste to a greater extent for energy recovery and material
recycling are being explored. For example, the plant in Timrå has a well-
functioning system for conversion of combustible process waste to marketable
F-22 Forest Products
FIG
. F-21 An ecological model “footprint.” (Source: AssiDomän.)
FIG. F-22 AssiDomän’s first delivery of FSC-labeled sawn timber products went to England in November 1997. The FSC
trademark indicates that the products come from well-managed forests, independently certified in accordance with the rules
of the Forest Stewardship Council (SGS-C-0081). (Source: AssiDomän.)
energy raw material, and several plants have installed systems for collection or
incineration of solvents.
᭿
Noise from plants and transport. Noise abatement measures are being
implemented at several plants.
᭿
Energy use. All mills are using exclusively fossil fuels as a thermal energy
source. Most of the fuels consist of fossil gas. Oil will be replaced wherever

possible. Environmental targets for reduced energy use are established annually.
᭿
Transport. A large portion of the business area’s environmental impact comes
from transport operations. Ways to improve transport are being investigated.
Sack manufacture
Sacks are made from paper based on unbleached or bleached sulfate pulp. The sacks
are mainly used for packaging building materials, food, chemicals, and animal feed.
(See Table F-7.)
The trend is toward lower paper weights per unit volume and fewer layers in the
finished sack, at the same time as the strength requirements on the paper have
risen. A mixture of recycled fiber, which is weaker, is rare. A new grade with
approximately 10 percent better strength properties was launched in 1997.
Lower packaging weights mean lower raw material, energy, and transport needs.
This also means reduced emissions to air and water.
The introduction of environmental issues systems (EMS) is under way and has
come farthest at the German plants, which achieved environmental certification/
registration. See Fig. F-23.
Prioritized environmental issues in connection with sack manufacture are:
᭿
Inks and adhesives. The introduction of ink rooms will reduce consumption of ink
and waste as well as associated transport. Water-soluble inks and adhesives will
gradually be introduced.
᭿
Wastewater, polluted with inks and adhesives. Existing treatment systems will
be optimized and new ones introduced.
᭿
Energy use. Reducing energy consumption is an environmental objective at many
mills. Fossil gas is the principal source of thermal energy. At Sepap, steam from
the nearby pulp and paper mill is used as a source of heat.
᭿

Waste management. Training of personnel and good control has led to a reduction
of process waste. Waste plans exist at many plants.
Forest Products F-23
TABLE
F-7 Production Data on Sacks
1997
Per 1,000
Total Sacks
Paper raw material, tonnes/kg 156,000 209
Fossil fuels, TJ/GJ 177 0.24
Purchased electricity, GWh/MWh 38 0.05
SO
2
, tonnes/kg* 9 0.012
NO
x
, tonnes/kg* 18 0.024
Landfilled waste, tonnes/kg 3,190 4.3
Sack production, tonnes 745
By-products to recycling, tonnes 5,660
* Estimated values.
᭿
Noise. Abatement measures have been introduced at plants in Italy and
Germany.
Carton material production data (production site: AssiDomän Frövi)
᭿
The aerated lagoon was converted into a long-term aerated activated sludge plant.
Treatment efficiency with regard to both phosphorus and COD is expected to
increase considerably compared with the previously used treatment plant. When
the converted treatment plant was put into operation, a large quantity of sludge

was released from the old treatment plant. The discharges exceeded the permit
guidelines.
᭿
A number of internal process measures were introduced. This will lead to reduced
discharges of COD to water, reduced emissions of particulates and sulfur dioxide
to air, and reduced discharges of odorous substances. See also Fig. F-24.
᭿
Production of TCF-bleached pulp, in which bleaching takes place without
chlorine-containing chemicals, began in 1997.
᭿
A study was made of the animal life on the bottom of Lake Väringen. The results
show that bottom conditions have improved steadily over the past few decades.
᭿
In connection with the development of the EMS, contractors who work at the mill
have received training in environmental practices.
Reference and Additional Reading
1. Soares, C. M., Environmental Technology and Economics: Sustainable Development in Industry,
Butterworth-Heinemann, 1999.
Fuel Gas Conditioning System(s)
One of the most important features of a fuel system is that it be acceptably free
from moisture or liquid droplets (if the fuel is gaseous) and other impurities (if the
fuel is gaseous or liquid). A typical system is outlined here.*
F-24 Fuel Gas Conditioning System(s)
FIG. F-23 At AssiDomän Sepap, one of Europe’s biggest manufacturers of sack paper and sacks,
pollution abatement measures have been approved for a total of MSEK 200. (Source: AssiDomän.)
*Source: Peerless, USA. Adapted with permission.
Fuel Gas Conditioning System(s) F-25
FIG.
F-24 Key environmental data for AssiDomän Frövi. (Source: AssiDomän.)
When gas pressure regulation and heating is not required, a filter separator or

vertical dry scrubber is recommended to remove the entrained solid and liquid
contaminants from the gas upstream of the turbine (see Fig. F-25). The vertical dry
scrubber is a high-efficiency multicyclone separator with constant pressure drop
and no replaceable internals. Due to a limited turndown ratio, it is recommended
that a separate scrubber be installed upstream of each gas turbine. When specified,
or necessitated by variable flow conditions, a filter separator is often used. Since
the elements must be periodically replaced, a duplex configuration consisting of two
100 percent units is recommended when protecting two or more gas turbines. As
with all of our fuel gas conditioning systems, full instrumentation for local and/or
remote monitoring can be supplied for either manual or fully automatic system
operation.
When gas is received from a transmission line at a much higher pressure than
required by the turbine, pressure regulating stations are included in the system
design as shown in Figs. F-26 through F-30. The simplest package consists of a
single skid with one or more 100 percent capacity pressure regulating valves (PRV)
placed upstream of the separator(s). This is shown in Fig. F-26.
In most cases, the PRVs must be protected from liquid slugs, which could be
present in the gas supply line. A vertical gas separator is the primary choice to
remove both liquid slugs and mist. Duplex filters or filter separators are located
F-26 Fuel Gas Conditioning System(s)
FIG. F-25 Position of vertical dry scrubber upstream of gas turbine. (Source: Peerless.)
FIG. F-26 Pressure regulating station (PRS) upstream of vertical dry scrubber. (Source: Peerless.)
FIG. F-27 Vertical gas scrubber upstream of pressure regulating station. (Source: Peerless.)
downstream of the pressure regulating station to complete the system as shown in
Fig. F-27.
Figures F-28 and F-29 show the addition of heating and metering. When
practical, all equipment is mounted on a single skid to facilitate ease of erection at
the site. If individual turbine metering is a requisite, manufacturers supply each
metering station on a separate skid that is easily installed in the field.
Figure F-30 is an example of a system requiring compression of the gas upstream

of the turbine. Some manufacturers offer a precompression gas conditioning
package, as well as pulsation dampeners and a high-efficiency vertical absolute
separator downstream of the compressor. Some manufacturers also offer both
analog and digital simulations to solve dampening and vibration difficulties.
Fuel Gas Conditioning System(s) F-27
FIG. F-28 Heater downstream of vertical gas scrubber. (Source: Peerless.)
FIG. F-29 Metering station upstream of gas turbine. (Source: Peerless.)
FIG. F-30 Pulsation dampeners upstream and downstream of compression station. (Source:
Peerless.)
Typical Range of Gas Conditioning Separators*
Vertical gas separators
Definition: Vertical vane-type separator with inlet baffle for high liquid loads with
liquid removal efficiency of 100 percent for particles of 10 microns and larger. See
Fig. F-31.
Filter separators
Definition: Vertical or horizontal two-stage separators for removal of solids and
liquids with liquid removal efficiency of 100 percent for particles of 8 microns and
larger and 99.5 percent for particles of 0.5 to 8 microns.
Solids removal efficiency: 100 percent for particles that are 3 microns and larger
and 99.5 percent for particles that are 0.5 to 3 microns.
Multitube filters
Definition: Vertical or horizontal single-stage filters for removal of solids.
Solids removal efficiency: 100 percent for particles that are 3 microns and larger in
size and 99.5 percent for particles of 0.5 to 3 microns in size.
Vertical dry scrubbers
Definition: Vertical multicyclone separator for removal of solids and liquids with
liquid removal efficiency of 100 percent for particles of 10 microns and larger.
F-28 Fuel Gas Conditioning System(s)
FIG. F-31 A vertical gas separator followed by two duplexed horizontal multitube filters is used to protect two gas turbines
in Nigeria. Piping and valves downstream of filters are stainless. (Source: Peerless.)

*Source: Peerless, USA. Adapted with permission.
Solids removal efficiency: 100 percent for particles of 8 microns and larger, 99
percent for particles of 6 to 8 microns, 90 percent for particles of 4 to 6 microns,
and 85 percent for particles of 2 to 4 microns. See Fig. F-32.
Vertical absolute separators
Definition: Vertical single or two-stage separator for removal of solids and very fine
mists with liquid removal efficiency of 100 percent for particles 3 microns and
larger, and 99.98 percent for particles less than 3 microns.
Solids removal efficiency: 100 percent for particles of 3 microns and larger, and 99.5
percent for particles of 0.5 to 3 microns.
Line separators
Definition: Vertical vane-type separator with liquid removal efficiency of 100
percent for removal of particles 10 microns and larger.
Fuel Systems; Fuel Flow Control
One* of the most common types of fuel flow control is electrohydraulic control. There
are electrohydraulic control solutions for differing environments, including low-
pressure and potentially explosive conditions.
Fuel Systems; Fuel Flow Control F-29
FIG. F-32 System installed in Saudi Arabia includes one vertical dry scrubber followed by two
pressure regulating valves and a line separator. A condensate drain tank is mounted alongside.
(Source: Peerless.)
*Source: J.M. Voith GmbH, Germany. Adapted with permission.
Modern industrial gas turbine systems require precise fuel dosage for the lowest
possible NO
x
emissions. Each application requires the right actuator and valve
combination to achieve exact, uniform fuel distribution to the burner. See Figs. F-
33 and F-34.
The controller needs to be:
1. Inherently reliable (robust construction and low-pressure hydraulics)

2. Equipped with single-stage signal conversion which results in fast, accurate
response times
3. Equipped with an oscillating magnet and minimized bearing forces to avoid
static friction effects
4. Easy to install because the magnet and control electronics are all one unit
5. A control with availability of 99.9 percent
The actuator is only one of the components necessary for accurate flow control. Some
controls OEMs cooperate with leading valve manufacturers to offer a total control
system. All valves and actuators are factory mounted and aligned to reduce labor-
intensive adjustments during commissioning.
Balanced valves have low force demands. Trip time of the complete valve
assembly is less than 200 ms and the related increase in pressure is absorbed by
the valve.
Valves are available with soft seals as well as with bellows for gaseous fuels.
For optimum performance and safety, electrical components face a burn test
operated under “cold” conditions. (See Figs. F-35 and F-36.)
Electrohydraulic actuators utilize an integrated position regulator that provides
a true position signal.
Other assembly features generally provided by actuator OEMs include:
1. Minimal interfaces
2. Valves designed to run without additional breakaway thrust, even after long,
continuous operation
3. Flange mounting for easy assembly
F-30 Fuel Systems; Fuel Flow Control
FIG.
F-33 Electrohydraulic actuator in a U.S. power station. (Source: J.M. Voith GmbH.)
FIG.
F-34 Section through an electrohydraulic actuator. Main components: 1, DC control magnet
with integrated control electronics; 2, control piston; 3, position sensor; 4, clamp magnet; 5, drive
piston; 6, piston rod; 7, stem; 8, stuffing box packing; 9, body; 10, trim; 11, fuel inlet; 12, seat.

(Source: J.M. Voith GmbH.)
F-31
4. Fail-safe design
5. Explosion-proof design
6. Controlled emergency trip
7. Ease of commissioning and installation
8. Low maintenance
9. Compact design
F-32 Fuel Systems; Fuel Flow Control
FIG. F-35 Schematic of gas turbine fuel system. ᭿
–
᭝
᭞
= control valve assembly, G = generator, T =
gas turbine. (Source: J.M. Voith, GmbH.)
FIG. F-36 Functional schematic of control valve assembly. X
0
= pressure P
A
at I = 0 or 4 mA; X
1
=
pressure P
A
at I = 20 mA; K
p
= proportional amplification; F
M
= magnetic signal/force; F
1

= feedback
force/signal to controller; F
A
= hydraulic cylinder force. (Source: J.M. Voith, GmbH.)