Technologies for Coal Utilization

Historically, coal use in the United States, from the 1800s to the mid-1900s, was primarily for iron and steel production, locomotives for transportation, and household heat. In addition, many chemicals, including medicines, dyes, flavorings, ammonia, and explosives, were produced from coal. With electrification of the United States beginning around 1950 and the feedstocks for chemical production shifting from coal to oil, the primary applications for coal use from 1950 to the present have been for electricity generation and the production of iron and steel. Coal is used in the industrial sector for producing steam and to a lesser extent electricity, and some chemicals are produced from coal. The technologies used for generating power, heat, coke, and chemicals will be discussed in this chapter and include combustion, carbonization, gasification, and liquefaction, which have been referred to as the four "grand processes" of coal utilization [1]. The emphasis of this chapter is on coal combustion, as this technology is the single largest user of coal.

Coal Combustion

Burning coal to generate heat is the most straightforward way of using coal. The heat that is generated from burning coal is used for warmth, cooking, and industrial processes. The use of coal for warmth, cooking, and metal works has been around for thousands of years. While the Chinese are credited with using coal as early as 1000 B.C. [2] and the first documented use of coal in Western civilization was by the Greek philosophers Pliny, Aristotle, and Theophrastus in the fourth century [3], coal was probably used by prehistoric man, as coal can be found at outcrops and often is easy to ignite. As discussed in Chapter 2 (Past, Present, and Future Role of Coal), the use of coal increased substantially during the Industrial Revolution but decreased with the discovery of oil and its use as a home heating and transportation fuel. Today, the use of coal for direct residential heating and industrial processes represents a small percentage of total coal consumption. The primary

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