REFURBISHMENT BY THE USE NON-ASBESTOS MATERIALS IN THERMO POWER PLANTS
By: Dipl. Eng.Alice Raducanu – INCDE-ICEMENERG
Angela Stanca – INCDE ICEMENERG Eng.
Dipl.Eng. Sandu Varlan - SC Termoelectrica-SA
Irimia – SC Termoelectrica-SA Eng.
Dipl.Eng. Liviu Radu - SE Bucharest
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
IN THIS FIELD 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
establishes the method for the determination of the asbestos powder
concentration in compliance with the provisions of the EEC Covenant. Based also
upon the Labor Protection Law, Specific Regulations for Labor Safety for
Asbestos Processing had been issued. These Regulations elaborated by the
Ministry of Labor and Social Protection are harmonized with the Directives No.
83/477/EEC and 91/382/EEC. They establish in detail regulations referring to
the obligations the enterprise management, workers, producers and suppliers
have with respect to asbestos; individual hygiene, cleaning at the workplace;
packaging, transportation and storage of the asbestos fibers, texture, coiling
and knitting of the asbestos fibers; operations for the processing and
finishing of the products containing asbestos and their use; removal of the
materials containing asbestos from the constructions, storage of the wastes;
provisions for designing works where asbestos is used. 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:
Rovinari, Turceni, Bucharest ,
and Borzesti Power Plant Branches 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:
Progresul, Bucharest-South, and Grozavesti. Determination of the asbestos fiber
concentration was performed in June-July 1999. Taking into account that no
previous registering of the asbestos fiber concentrations was available for
these units a strategy for assessment was applied where several samples were
taken of 30-minute duration at each workplace.
The asbestos fiber concentration at the respective workplaces was
calculated as the weighted mean value with the time of these determinations.
The method used for the determination of the airborne asbestos fiber
concentration at the workplace is RTM-1 approved by WHO and ISO (Determination of the number concentration of
airborne inorganic fibers by phase contrast optical microscopy. Membrane filter
method, third Edition Little Brown, 1995). The samples were individual,
each worker being attached a sampler separately. The analysis of the samples
was carried out by help of the phase contrast optical microscopy using a NICON
microscope. The filters had been made previously transparent in acetone vapors
at 75oC. The criteria for counting the fibers are: Braila
- diameter < 3 лm
- length > 5 лm
- ratio length/diameter > 3/1
The results of these determinations are shown in the table below.
Fiber Concentration (fiber/ccm)
1. Left-hand header – reheated steam. Boiler 1A
2. Turbine 1K200-130
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
Bucharest-South power plant
1. Turbine 5. Main steam valve. Level 58
2. HP valve armatures
Grozavesti power plant branch
HPP discharge set
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 (West,
Progresul, Grozavesti, South), Bucharest ,
Borzesti power plant branches. At the request of INCDE-ICEMENERG and
Termoelectrica delivered data about the behavior of the glands mounted on the
equipment established. The behavior of the glands was very good in 80% of the
cases (about 5000 hours of operation since glands mounting to the date). 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’”
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
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).
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