Coal liquid fuel utility boiler fuels

Evaluation of Coal-Derived Liquids as Utility Boiler Fuels... 

Demonstrate the use of coal derived liquids as potential substitutes for petroleum fuel oil in a full scale, wall fired utility boiler. 

Overall, the consensus of the participants 1s that any of the six coal derived liquids could be considered as an acceptable replacement for liquid petroleum fuel 1n either Plant Sweatt boiler with no equipment modifications, equipment additions or environmental variances. The application or replacement usage of these coal derived liquids 1n other utility boilers would not seem to be any more difficult but should be prefaced by an extensive, Individual site assessment of candidate units. The few modifications required at Plant Sweatt Indicate that a limited number of design criteria would be affected 1f these six synthetic liquids were to be Included 1n the fuel specifications of future utility boilers. The handling and emission characteristics of coal derived liquids may even be preferable to certain petroleum liquids 1n some utility applications. 

Today, the planned installation of new oil fired steam boilers is essentially nil. Table II shows that approximately 96,000 mw of capacity will remain in place in 1987. These units were put into service primarily in the mid-1960fs and have 10-30 years of useful life remaining. Installed capacity of liquid fueled combined cycle units is expected to grow from 3000 to 8000 mw over this time period. These units generate electricity more efficiently than conventional boilers. Combined cycle capacity is projected to be utilized much more extensively than in the past. As a result, the anticipated quantity of power generated from combined cycle equipment may increase nine-fold from 4,000 to 36,000 million Kilowatt hours as shown in Table III. Unfortunately, the future use of petroleum liquids for this kind of operation has been jeopardized by the recently legislated Fuel Use Act. This Act requires coal to be used instead of petroleum for new power stations. 

It is anticipated that coal derived liquids boiling above about 350 F will be disposed of to the utility market. Table V summarizes the potential utility markets for various types of coal derived fuels which include solvent refined coal, heavy boiler fuels, distillate boiler fuels, turbine fuels and methanol. Speculative locations for these markets are indicated on Figure 2. 

In 1979, because of a lack of large samples, boiler fuel test programs will be limited to small scale equipment. However, in 1980, large samples of liquids in the 5,000-10,000 barrel range should become availabel from the H-Coal pilot plant at Catlettsburg, Kentucky and the Exxon Donor Solvent process at Baytown, Texas. It would be preferable to run a number of tests utilizing different utility sites and types of electric generation... 

In other fuel markets, coal liquids can be more competitive. Industrial boilers presently are not amenable to stack gas scrubbing. The same is true of smaller utility plants. In particular, peak load units require a clean, storable liquid fuel as an alternative to natural gas. However, the high viscosity of primary coal liquefaction products is undesirable for many of these applications. Also, their residual sulfur and nitrogen contents may be excessive as emission standards become more stringent. 

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