- CHEMICAL CLEANING
- STEAM BLOWING
- TURBINE OIL FLUSHING
Thermal power plants using fossil fuel (coal, lignite, etc.) generate steam which drives a turbine coupled to an electric generator. The turbine in combined-cycle (CC) power plants will be primarily driven by ignited gaseous fuel and the spent hot gas is used to generate steam (HRSG – Heat Recovery Steam Generator) which drives another turbine or another section of the same turbine. In both cases, the boiler (steam generator) has to transfer heat from the burning fuel to water to generate high-pressure steam. In order to maximize the heat transfer and ensure that there no “hot spots” in the boiler, the metal surface has to be perfectly clean, i.e. free of oil, grease, rust, weld slag and other contaminants introduced into the boiler during construction or due to chemical reaction of the boiler metal with its environment. |
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Small boilers may be cleaned mechanically, say by wire-brushing, but larger boilers are cleaned more effectively using chemical means. Alkalis are used to remove oil, grease and any organic residues. Acids are used to remove oxides (rust, mill-scale), chlorides and silica. Chelating agents such as EDTA, NTA are also used instead of acids. High velocity flushing with de-ionized water is carried out before and after each stage to remove all loose debris and chemical residues. After chemical cleaning, the boiler metal must be “preserved” to prevent re-oxidation. Tandex has the capability and the experience of using different chemistries for achieving a high degree of cleaning in the most cost-effective manner. Tandex would like to recommend state-of-the-art chemical cleaning procedures which can give superior results in less time and at substantially reduced costs. |
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Tandex offers chemical cleaning services which include:
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The steam driving a turbine must be extremely clean, i.e. there should be no particulate matter which can impact and damage the turbine blades. The steam generated in a boiler and passing through other sections such as the superheater, reheaters, etc. can pick up loose debris, scale etc. which can cause severe damage to the turbine. Even if the boiler has been chemically cleaned, it is still necessary to fire up the boiler and blow the steam to the atmosphere (using specially designed arrangements) to ensure that the desired levels of steam purity are achieved.
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Turbines are shaft mounted on heavy-duty bearings and need continuous oil lubrication. Before the turbine can be put into operation, the lube-oil circuit has to be completely cleaned of all contaminants to prevent damage to the shaft and bearings. This is carried out by re-circulating the lube-oil through a temporary circuit to remove all grit and scale. The oil-flushing operation may take several days to complete to ensure that the particulate matter concentration in the oil is reduced to less than the pre-set levels. |
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Tandex has the experience and expertise to:
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