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Show blading was observed. A chromium based coating was introduced and eliminated the corrosion problem. In other plants, because of the high alkali and metal content in the dust, heavy incrustration was noticed, similar to those observed with ash bearing liquid fuels. The fouling of the turbine was successfully controlled by introducing silicon additives, where natural silicates were absent from the dust. This experience with blast furnace gases is of great value to the development of modern gas turbine power plants, since the combustion of low heating value fuels originating, e.g., from coal gasification is a real prospect. IV. CRUDE AND HEAVY OIL FIRED BBC MACHINES Since 1948, over 85 BBC gas turbines with a total operating capacity of about 3200 MW were installed for crude oil service. Practical experience with the machines was described elsewhere [3, 5]. The latest 1984 addition to the already existing 1600 MW capacity BBC gas turbines in Riyadh, Saudi Arabia [3], is the 200 MW extension of the 800 MW site capacity Riyadh 8 power plant, shown in Figure 4. These machines are fired with Saudi Arabian light crude oil whose typical properties are listed in Table 3. Among the undesirable properties of heavy oils and crudes, we mention their high ash and metal contents. Ash may induce blade fouling and thereby reduce the power output, whereas heavy metals, especially vanadium and lead, are sources of fast oxidative corrosion. Alkali sulfates act as fluxing agents and may thereby increase fouling and cause hot corrosion. Sodium and potassium contents are usually reduced by conventional crude washing, followed by electrostatic or centrifugal separation. The deleterious effects of the other metals are controlled by the addition of magnesium and silicon containing compounds. The strategy of fouling and corrosion prevention was described by P. Felix [4]. However, there is an economic penalty in the use of the lower priced dirtier fuels. Examples for these include: 1.4.4 |