Coal generated steam

Coal generated steam Oil generated steam Electrical Energy Direct Fired Gas ... 

In 1990, a test using scrap tires (2x2 in. I DE) to generate steam for electricity was conducted at the Elexsys plant. The I DE replaced 20% of the plant s coal. Results showed that IDE is an environmentally sound fuel. Particulate emissions were reduced by the lower ash content of IDE, volatile organic compounds (VOC) were reduced because of more efficient burning of I DE compared to coal, and carbon dioxide emissions were reduced because I DE contains half the fixed carbon found in coal. Nitrogen oxide, chlorine emissions, and metals were also reduced, and ferrous metals and dioxins were nondetectable (7). 

Flue Ga.s Desulfuriza.tion. Citric acid can be used to buffer systems that can scmb sulfur dioxide from flue gas produced by large coal and gas-fired boilers generating steam for electrical power (134—143). The optimum pH for sulfur dioxide absorption is pH 4.5, which is where citrate has buffer capacity. Sulfur dioxide is the primary contributor to acid rain, which can cause environmental damage. 

The failure took place in a large water-tube boiler used for generating steam in a chemical plant. The layout of the boiler is shown in Fig. 13.1. At the bottom of the boiler is a cylindrical pressure vessel - the mud drum - which contains water and sediments. At the top of the boiler is the steam drum, which contains water and steam. The two drums are connected by 200 tubes through which the water circulates. The tubes are heated from the outside by the flue gases from a coal-fired furnace. The water in the "hot" tubes moves upwards from the mud drum to the steam drum, and the water in the "cool" tubes moves downwards from the steam drum to the mud drum. A convection circuit is therefore set up where water circulates around the boiler and picks up heat in the process. The water tubes are 10 m long, have an outside diameter of 100 mm and are 5 mm thick in the wall. They are made from a steel of composition Fe-0.18% C, 0.45% Mn, 0.20% Si. The boiler operates with a working pressure of 50 bar and a water temperature of 264°C. 

Develop an episode control scenario for a single large coal-fired steam electric generating station. 

With an estimated 400 years of coal available for future power generation, coal-powered steam turbines are expected to continue to dominate global electricity fuel markets. 

In the United States, coal had a 57 percent share of the electric power fuel market in 2000, up from 46 percent in 1970. This amounts to 430,000 MW generated by steam turbines that are fueled with coal. Wlien considering other sources of generating steam for electric power—such as nuclear reactors, gas- or oil-fired broilers, and waste heat from gas turbines— steam turbines now comprise more than 600,000 MW of capacity, or approximately 75 percent of all generating capacity in the United States. 

The reaction of steam with coal generates a 1 1 gas mixture of H2 and CO. Hydrocarbon formation requires a 2 1 mixture, so additional H2 is produced by the reaction of steam with some of the CO ... 

Note The LHV to HHV ratio of 90% for methane (21,526/23,881 = 90 %) is typical of that for natural gas, while this ratio is roughly 94% for fuel oils. Common coals typically have a LHV to HHV ratio of 92 to 96% depending upon the hydrogen and moisture content. Typically, gas turbine based cycles are presented on an LHV basis. Conventional power plants, such as coal-, oil-, and gas-fired steam generator/steam turbine cycles are presented on an HHV basis within the U.S, and on an LHV basis in the rest of the world. 

In order to ensure a consistent supply of coal for steam generation, plants typically maintain an outdoor 90-day reserve supply. The pUes are usually not enclosed, so the coal comes in contact with moisture and air, which can oxidize metal sulfides to sulfuric acid. Precipitation then results in coal pile runoff with minerals, metals, and low pH (occasionally) in the stream. 

It was soon closed in, and an attempt was made to bum it, as natural gas is usually burned, for generating steam for drilling purposes. Much to the surprise of parties interested, it would not bum. Later it was found that when a fire was already kindled in a fire box or an engine and the gas turned on,. .. it would begin to bum and would develop sufficient heat to generate steam moderately well. But as soon as the coal or other fuel in the firebox was consumed, the gas would no longer bum. 

Fluidized-bed combustors are complex chemical reactors, a fact often overlooked because their primary purpose is to generate steam and electricity. The reactions of importance in fluidized beds include those relating to coal combustion,... 

In the Fisher-Tropsch process, carbon monoxide is generated by treating coal with steam, a process called coal gasification. 

TABLE 14.7 Energy and Availability Losses in a Coal-Fired Steam-Electric Generating Plant ... 

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