REFURBISHMENT
BY THE USE NON-ASBESTOS MATERIALS IN THERMO POWER PLANTS
By: Dipl.
Eng.Alice Raducanu – INCDE-ICEMENERG
Dipl.
Eng.
Dipl.Eng.
Sandu Varlan - SC Termoelectrica-SA
Dipl. Eng.
Dipl.Eng. Liviu Radu - SE Bucharest
Summary
At an international
level, the trends in the developed civilized states are in favor of the full
replacement of the asbestos because it is a very carcinogenic material.
By introducing the
non-asbestos materials, there shall be reduced:
·
energy consumption due to the more reduced
friction coefficients
·
operating fluid losses, the new materials
requiring lower leakage for cooling and lubricating purposes due to the thermal
transfer coefficient better than the one of the asbestos which is a thermal
insulator
·
spares cost due to the low wear of the
protection bushings owing to the better friction coefficients and less required
tightening
·
labor costs, because the interventions are
less frequent due to the high reliability of the new materials
·
production loss costs as well as the
shutdown/start-up costs of the units (especially the high capacity units).
1.
Short Description of the Activity
Asbestos is a
collective notion for a group of mineral silicates of the serpentine type
(chrysotile) and amphibole type (anthophyllite, tremolit, actinolit, amosite
and crocidolite).
According to the
provisions of the General Regulations for
Labor Protection, 1996, Appendix 17, the goods containing asbestos are
included under item 3 as carcinogenic ones for the human being. The main
characteristics of asbestos fibers that relate to the incidence and severity of
asbestos refer to the diameter and length of the fiber, the durability in the
respiratory tract and the type of asbestos fibers. As the adverse health
effects result from the inhalation of fibers, only fibers that are inhaled and
deposited on the respiratory tract can cause the disease. Only fibers thinner
than 5 μm, having an aerodynamic
diameter of 3 μm can enter the conductive airways of the respiratory tract.
Longer asbestos fibers are more dangerous than the shorter ones. Due to these
considerations the determination of the dangerous conditions can be done only
by counting the respective fibers at the microscope with phase contrast while
for the differentiation of the types the electronic microscopy is used.
According to the
latest research works it seems that the bio-aggressiveness of the asbestos
fibers depends on some peculiarities of the surface, related to the chemical
composition, represented by the acid-base chemical reaction, dominated by the
binding groups OH and SiOH.
The mechanisms are
explained by the “ion-exchange” phenomena. This condition was also demonstrated
through the reduction of the simultaneous bio-aggressive effect to more than
400oC, for the chrysotile fibers.
The
pathogen effects of the asbestos refer to : asbestosis (diffuse lung fibrosis),
lung cancer in association with lung fibrosis; other kinds of cancer (larynx or
other places); pleural plates, pleural effusions.
The asbestos fiber
exposure period up to morbid phenomena occurrence varies a lot depending on the
level of the fibers in the working area, ranging from a few years up to 15-20
years or more.
The most severe forms
are the carcinogenic type diseases (bronchia-lung cancer, mesothelioma or other
locations of the cancer).
Unfortunately,
the diagnosis of such diseases is usually tardy when medical intervention
(especially the surgery one) is no longer feasible. Such severe diseases occur
even earlier with the smokers. Smokers exposed to asbestos fibers are at a
considerable greater risk of developing lung cancer than non-smokers.
The insufficient
preoccupation of the economic agents for providing the material basis necessary
to monitor the personnel exposed to the asbestos fibers led to the
non-cognition of the real health condition of these employees. Under the
circumstances in which, at the insistence of the health authorities, some
enterprises made available the material basis (especially roentgen films of
large format) and the medical staff got engaged in the specific investigations
(standard lung radiographs, functional ventilation tests, cytological
examination of sputa, etc.) an increased percentage of diffuse lung fibrosis
(asbestosis) has been found out.
Within the secondary
legislation field, specific regulations for labor safety concerning asbestos
had been worked out by MMPS; such regulations had been harmonized in line with
the EU Directives No. 83/477/EEC and 91/382/EEC .
2. EUROPEAN LEGISLATION CONCERNING THE PROTECTION OF THE
WORKERS FROM THE RISKS CAUSED BY EXPOSURE TO ASBESTOS FIBERS.
The first enactment
is represented by the Directive 83/477/EEC, amended by Directive 91/382/EEC,
both referring to activities where the workers are exposed to asbestos. These
directives enumerate the detailed requirements aimed at minimizing the adverse
effects caused by asbestos on health. The main measures established by
Directive 83/477/EEC refer to: assessment of the workers’ exposure to the
asbestos fibers, reduction of the quantity of asbestos used as well as the
reduction of the number of personnel exposed at asbestos; regulations to avoid
the discharge of powders in the air at work, conditions for the transport and
storage of the wastes containing asbestos; prohibition of using the asbestos
for works supposing asbestos-turning into powder in association with the risk
of its scattering in the outside environment; establish maximal acceptable
limits at the place of work and methods for the measurement of the airborne
asbestos fibers from the workplace; establish the main preventive measures at
the workplaces where asbestos fibers are discharged as well as regulations for
the protection of the workers (supply respiratory protective equipment, forbid
smoking, arrange clean areas for having lunch, secure the storage and cleaning
of the protection equipment at the workplace, sanitary installations for
individual hygiene, and so on); conditions and methods are established for the
periodical examination of the workers exposed to asbestos.
Council
Directive No.83/477/EEC aims at reducing the pollution of the environment
caused by the industrial utilization of the asbestos (processes using more than
100-kg asbestos annually). Risks for the ambient air, soil and water pollution
is envisaged. Diminishing of the asbestos scattering risk in case of the
demolition works is also envisaged. Council Directive 91/659/EEC prohibits both
marketing and use of almost all types of asbestos goods except some goods
containing chrysotile (whose application is restricted to a limited range of
goods).
3.
LEGISLATION EXISTING IN ROMANIA
At present, in
conformity with the provisions of the Labor Protection Law as of 1996, the General Regulations for Labor Protection
establish the maximal concentration acceptable for the asbestos powders at the
workplace at 1 fiber/ccm (length > 5лm, diameter < 3 лm and the ratio of
the two dimensions higher than 3/1).
A regulation worked
out by the Public Health Institute
from Bucharest
In order to adopt the
provisions of the CEE Directives a Government Decision has been drafted
including terms for the prohibition of using all kinds of asbestos except the
chrysotile, measures for the self-assessment of the risk in the works related
to the exposure at asbestos fibers etc. The Government Decision draft is under
the course of obtaining the approvals of all the relevant ministries so that it
could be submitted to the approval of the government.
4. TECHNICAL SOLUTIONS FOR THE SUBSTITUTION OF THE
ASBESTOS SEALING MATERIALS WITH NON-ASBESTOS SEALING MATERIALS. Case Study: Bucharest Oradea
INCDE-ICEMENERG
through its Environment and
Ecotechnologies Department approached some optimal technical solutions for
the substitution of the asbestos sealing materials from the thermal power
plants with non-asbestos sealing materials and established the economic
efficiency of non-asbestos sealing materials application.
A number of materials
are available to be used as substitutes of asbestos. Such materials are: the
composites based on fibers, Teflon (the chemical substance used to make Teflon
is the polytetrafluoretylene, acrylic fibers (artificial fibers in which the
substance they are made from may be any synthetic polymer with long chain in
which 85% from the weight is represented by acrylic-nitrite units
(-CH2-CHiCNs-)x) aramida fiber (coming out from the chemical
reaction between the di-amine aromatics and di-acid aromatics chlorides),
poly-olefin fibers (polymers with long
chains in which at least 85% from the weight is represented by ethylene, propylene or olefins), carbon/graphite fibers
(filament-like profiles of carbon obtained at high temperatures), glass fibers
(fibers made of calcium, sodium silicates and other metals), INCONEL
(corrosion-resistant alloy – particularly in relation to organic acids, at hot
condition – with 79.5% Ni, 13% Cu, 5.5%
Fe, 0.2% Cu, 0.25% Mn, 0.08%C), MONEL (alloy with 65-70% Ni, 25-30% Cu, the
remaining being Mn, Fe, Si, C,S, P), silicon rubber (thermo-plastic elastic
product containing linear or cyclic organic silicon macro molecular compounds
with quite varied chemical structures
and properties, paraffin (paraffin hydrocarbon mixture CnH2n=2,
with melting temperature exceeding 34oC), etc .
The asbestos cords
have the physic-chemical properties and composition described under Chapter 1.
From the experience accumulated so far in the thermal power plants there
results that the asbestos sealing glands for valves and pumps have a shorter
lifetime requiring frequent replacement of the packing glands. Because of the
deterioration, the asbestos packing glands caused damages, which lead to the
shutdown of the unit while considerable costs were needed for the shutdown and
start up of the units.
The non-asbestos
material cords are featured by longer lifetime than the asbestos ones as a
result of the research made by the manufacturing companies with a view to
overcome the economic effect of the high prices.
5. COLLABORATION BETWEEN SC TERMOELECTRICA-SA AND
INCDE-ICEMENERG FOR NON-ASBESTOS MATERIAL USE
With
a view to line up with the provisions of both national and UE legislation, SC
Termoelectrica-SA initiated a number of collaborations with INCDE-ICEMENERG.
These collaborations are described below:
In 1999,
INCDE-ICEMENERG prepared “Solutions for
the replacement of the asbestos-containing-materials from CONEL thermal power
plants” Aware of the fact that the asbestos and asbestos materials will
continue to remain in the power installations to be used for another period of
time, in the first stage the
specific procedures have been prepared for the supply, transportation, storage,
handling and use of the asbestos and asbestos-containing materials. All such
specific work procedures were disseminated to all the thermal power plants
under Termoelectrica’s subordination. The existing procedures to be used until
all asbestos materials are substituted by non-asbestos ones do not give a 100%
safety guarantee. PowerGen issued a “Guide
for operating with asbestos in safety”. When working out the procedures,
ICEMENERG took into account PowerGen’s instructions because such instructions
refer strictly to the thermal power plants. The trends at an international
level are in favor for the complete substitution of the asbestos.
Within the second stage of the work, measurements
had been executed for the airborne asbestos fiber at the workplaces for the
following power plant branches: Braila
- diameter < 3 лm
- length > 5 лm
- ratio
length/diameter > 3/1
The results of these
determinations are shown in the table below.
|
Workplace
|
Fiber
Concentration (fiber/ccm)
|
|
1. Left-hand header – reheated
steam. Boiler 1A
2. Turbine 1K200-130
|
0.56
0.51
|
|
Progresul power plant from
1. Level 13. Steam and water valve.
Boiler feed – knot inlet
2. Valve sectioning – boiler 1
3. Connection valve. Left side bar –
boiler 1. Hammering + cutting
4. Connection valve. Left side bar –
boiler 1. Erection
|
0.48
0.52
0.55
0.18
|
|
Bucharest-South power plant
1. Turbine 5. Main steam valve.
Level 58
2. HP valve armatures
|
0.59
0.53
|
|
Grozavesti power plant branch
HPP
discharge set
|
0.54
|
Comparing
the results from the analysis bulletins with the limits accepted by the General Regulations for Labor Protection,
the momentous concentrations are at the limit of disease exposure risk. With
respects to the Directive 91/382/CEE that is under the course of being adopted
by Romania (for events of using chrysotile fibers only the limit acceptable for
a standard eight hours period is 0.60 fiber/ccm; for a mixture of several kinds
of fibers the acceptable asbestos limit is 0.30 fiber/ccm) it was found out
that, except the erection operation from the connection valve, left side bar –
boiler 1 from Progresul power plant, Bucharest, all the other values exceed the
acceptable asbestos fiber limit for an exposure period of eight hours a day by
1.6-2 times.
Mention
should be made that the asbestos fibers inhaled in the organism cannot be
eliminated and they continue to have adverse effects during the lifetime
(asbestosis, lung cancer and mesothelioma).
Following
the “Solutions for the replacement of the
asbestos-containing-materials from CONEL thermal power plants” completed in
1999, ICEMENERG was ordered the study “Economic
efficiency of the non-asbestos cord. Case study based on the experiments the
oferrers make for Termoelectrica free of charge” consisting of the
following issues:
-
select jointly with Termoelectrica the thermal power plants and equipment for
the industrial applications
-
nominate the companies that agree upon the free of charge testing of the
non-asbestos materials
-
industrial application
-
monitor the behavior of the non-asbestos materials in operation based on some
monitoring sheets
-
evaluate the economic efficiency of the non-asbestos cord utilization based on
its behavior in operation.
In
2000, ICEMENERG together with other companies that supply or manufacture
non-asbestos sealing materials mounted experimentally in the installations a
number of packing glands for certain pumps and valves, at various operating
parameters, in the power plant branches of Termoelectrica. The aim of the
experiment was to determine the number of hours of operation of the packing
glands made from the non-asbestos materials obtained from the Romanian
suppliers for pumps and valves for various operating regimes. For the
correctness of the experiment, the packing glands had been installed observing
the following conditions:
-
proper selection of the packing type and material depending on the operation
conditions
-
meet the conditions required for the surface of the packing (mainly the roughness
of the shaft)
-
correct mounting of the non-asbestos packing glands
-
secure even from the beginning conditions for careful monitoring (registering)
of the packing gland behavior.
The
non-asbestos packing glands installed on the various equipment were made of:
graphite-teflon (SC IZOLATORUL SA, Suszi); expanded graphite with textile fiber
texture (Burgmann); expanded graphite with inconel insertion (Suszi); pure graphite with inconel insertion
(Danemar, Petprod, Izolatorul); carbon fiber with inconel insertion
(Exclusive); pure expanded graphite with pre-formed inconel and pressed
graphite bottom ring (Avko); graphite reinforced with carbon fiber (Petprod);
carbon fiber (Elmeco); tefloned graphite (Elmeco); graphited carbon (Braflex,
Exclusiv); PTFE fiber with silicon and graphite (Izolatorul); graphited teflon
+ tefloned Kevlar (Izolatorul); tripp texture made from free of silicon
non-impregnated teflon (Gasket); ramie (Markel).
Termoelectrica
made the decision upon the power plant branches and equipment where packing
glands were mounted with preference on the high capacity units that were going
to operate a high number of hours in the summertime of 2000. The units were
from Turceni, Craiova Oradea Bucharest Ploiesti Galati
Calculation of the
economic efficiency when using non-asbestos sealing materials
The
economic effect of using the non-asbestos materials results mainly from the
reduction of the unit non-operation periods of time caused by damages having as
roots the valves shutdown through the deterioration of the asbestos sealing
materials.
C1 - Savings resulted
through the avoidance of damages
C1 = C1’ + C1” + C1’”
where:
C1’ = the
value of the non-generated electric energy production during the shutdown of
the unit for damage remedy purposes
C1’
= cost of the generation unit shutdown
C1’” = labor
cost for the replacement of the fault packing gland (insignificant)
Taking
into account an average number of minimum 6 shutdown hours caused by some
damages because of the non-operation of the valves due to the deterioration of
the asbestos sealing materials, the power of a unit (50 and 330MW) and an
average price of the electric energy at 33$/MWh, the following cases resulted:
For a 50MW unit
C1’=
(shutdown number of hours) x power of the unit (MW) x electricity price =
6 hours x 50MW x 33$/MWh = $9900
= ROL 305 millions
C1’
= ROL 32 millions
C1’”
= ~ 0
Total:
C1 = C1’ + C1” + C1’” = ROL 339 mil.
For a 330MW unit
C1’
= (shutdown number of hours) x power of the unit (MW) x electricity price =
6 hours x 330MW x 33$/MWh = $65340
= ROL 2026 millions
C1”
= ROL 380 mil.
C1’”
= ~ 0
Total:
C1 = C1’ + C1” + C1’” = ROL 2406 mil.
C2
= Price difference between the non-asbestos packing glands and asbestos packing
glands for valves and pumps.
Taking
into account the demand of asbestos glands for one year, depending on the
quantity of asbestos packing material used (graphited asbestos with insertion,
graphited asbestos without insertion, non-soaked asbestos) for the 50 and 330MW
units, the following would result:
Asbestos packing
glands
a)
For the 50MW unit (demand of
asbestos packing glands for one year established on the basis of the
discussions held with the operation personnel from Bucharest-South power
plant):
a1)
Graphited asbestos with insertion, about 110kg = 110kg x 12.5 $/kg = 1375$ =
42.63 mil ROL
a2)
Graphited asbestos without insertion, about 230kg = 230kg x 8 $/kg = 1840$ =
57.04 mil ROL
a3)
non-soaked asbestos, about 100kg = 100kg x 9$/kg = 900$ = 27.9 mil. ROL
Total: a1 + a2 + a3 =
127.6 mil ROL
Price
of the asbestos packing glands purchased from IZOLATORUL Co.
b)
For the 330MW unit (demand of
asbestos packing glands for one year established on the basis of the
discussions held with the operation personnel from Bucharest and Rovinari power
plant branches)
b1)
Graphited asbestos with insertion, about 200kg = 200kg x 12.5 $/kg = 2500$ =
77.5 mil ROL
b2)
Graphited asbestos without insertion, about 600kg = 600kg x 8 $/kg = 4800$ =
148.8 mil ROL
b3)
non-soaked asbestos, about 200kg = 200kg x 9$/kg = 1800$ = 55.8 mil. ROL
Total: b1 + b2 + b3 =
282 mil ROL
Price
of the asbestos packing glands purchased from IZOLATORUL Co.
Taking
into account the demand of non-asbestos glands for one year, depending on the
quantity of non-asbestos packing material used (graphited non-asbestos with
insertion, graphited non-asbestos without insertion, non-asbestos teflon) for
the 50 and 330MW units, the following would result:
a) Non-asbestos
packing glands
a)
For the 50MW unit (demand of
non-asbestos packing glands for one year established on the basis of the
discussions held with the operation personnel from Bucharest-South power
plant):
a1)
Graphited non-asbestos with insertion, about 100kg = 100kg x 80 $/kg = 8000$ =
248 mil ROL
a2)
Graphited non-asbestos without insertion, about 200kg = 200kg x 65 $/kg =
13000$ = 403 mil ROL
a3)
non-asbestos teflon, about 100kg = 100kg x 70 $/kg = 7000$ = 217mil. ROL
Total: a1 + a2 + a3 =
868 mil ROL
Average
price of the non-asbestos packing glands as resulted from the communications of
the companies participating in the study.
b) For the 330MW unit (demand of
asbestos packing glands for one year established on the basis of the
discussions held with the operation personnel from Rovinari power plant branch)
b1)
Graphited non-asbestos with insertion, about 200kg = 200kg x 80 $/kg = 16000$ =
496 mil ROL
b2)
Graphited non-asbestos without insertion, about 600kg = 600kg x 65 $/kg =
39000$ = 1209 mil ROL
b3)
non-asbestos teflon, about 200kg = 200kg x 70$/kg = 14000$ = 434 mil. ROL
Total: b1 + b2 + b3 =
2139 mil ROL
The
average price of the non-asbestos packing glands resulted from the
communications companies participating in the study.
Price
additional difference due to the non-asbestos pacing material application for
the 50 and 330MW units:
For one 50MW unit:
non-asbestos
packing glands – asbestos packing glands =
C2
= 868 mil ROL – 127.6 mil ROL = 740.4 mil = Investment
For one unit of 330MW
non-asbestos
packing glands – asbestos packing glands =
C2
= 2139 mil ROL – 282 mil ROL = 1857 mil ROL = Investment
Taking
into consideration that during one year at a generation unit having a high
number of operating hours (more than 6000) at least 3 damages are caused
because of the interventions at valves and pumps due to the deterioration of
the asbestos packing glands while the non-asbestos packing glands do not fail
under damage regime, under the situation in which the maintenance operation are
optimally organized taking into account the known lifetime, then the following
benefits shall be obtained for the 50 and 330MW units:
For one unit of 50MW
For
3 damages/year: 3x339 mil/damage = 1017 mil = Benefit
Saving
= Benefit = Investment
Saving
= 1017 mil – 740.4 mil = 276.6 mil/year
ee
= economic efficiency = B/I = 1017 mil/740.4 mil = 1.37 ROL/1 invested ROL
Return
time = I/B = 740.4 mil/1017 mil = 0.73 years
For one unit of
330MW:
For
3 damages/year: 3x2406 mil/damage = 7218 mil = Benefit
Saving
= Benefit = Investment
Saving
= 7218 mil – 1857 mil = 5361 mil/year
ee
= economic efficiency = B/I = 7218 mil/1857 mil = 3.89 ROL/1 invested ROL
Return
time = I/B = 1857 mil/7218 mil = 0.26 years
7. CONCLUSIONS
The
cost of the non-asbestos materials is high (about 200 DEM/kg) in comparison
with the one of the asbestos materials (about 22 DEM/kg) what could induce even
from the beginning the idea of economic inefficiency. In fact, as resulting
from the experiments carried out within SC Termoelectrica-SA, following a
comparative technical-economic analysis the utilization of the non-asbestos
materials was found out to be more efficient (reduced number of replacements,
reduced labor, eliminated unavailability times, reduction to zero of the costs
related to the damages caused by the deterioration of the packing glands).
The
evaluation factor for the future biddings organized by Termoelectrica-SA for
the purchase of the non-asbestos cords are:
-
The ratio price/kg/lifetime of the
packing glands indicating the economic efficiency of the packing glands
to be calculated on the basis of both the tendered prices and lifetime of the
packing glands described in the study of ICEMENERG;
-
The lifetime as a separate
evaluation factor is the factor on which the optimal organization of the
maintenance activity from thermal power plants depends.
Besides
the necessity of replacing the asbestos due to the adverse effects it has on
the personnel health, the utilization of the non-asbestos materials brings in
significant economic effects whose analysis leads to the conclusion that they
are superior to asbestos. The benefits derived from the replacement of the
asbestos result in:
·
reduction of the energy consumption due to
the more reduced friction coefficients;
·
reduction of the operating fluid loss; the
new materials having lower leakage for cooling and lubrication due to a better
thermal transfer coefficient of the asbestos that is a thermal insulator;
·
reduction of the costs for spares because of
the low wearing of the protection bushes due to the better friction
coefficients and reduced required
tightening;
·
reduced labor costs, interventions being less
frequent due to the high reliability of the new materials;
·
reduction of both the production loss cost
and unit shutdown/start-up cost (especially for the high capacity units).
BIBLIOGRAFIE
1.
The Control of Asbestos at Work (Amendament) Regulations 1992
2.
Asbestos : the control of asbestos at work (second edition) : Control of
Asbestos at Work Regulations 1987
3.
Guidance on Asbestos Safety
4.
Environmental Protection Act 1990
5.
The Control of Asbestos in the Air Regulations 1990
6.
The Asbestos (Prohibitions) Regulations 1992
7.
OSHA Regulations (Standards – 29 CFR) – Asbestos – 1910.1001
- Asbestos – 1915.1001
-
Asbestos - 1926.1101
8. STAS 7019 / 1980 : Pl`ci de azbest pentru garnituri
9. STAS 7018 / 1990 : }nur de azbest pentru garnituri
10. STAS 3498 / 1987 : Pl`ci de azbest cu cauciuc pentru
garnituri (Pl`ci de marsit)
11.
The Chemicals (Hazard Information and Packaging for Supply)
12.
The Special Waste (Amendament) Regulations 1996
13. Norme specifice
de securitate a muncii pentru prelucrarea azbestului
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