Boiler feedwater preparation

Water effluents are not a problem in coal gasification plants. In fact, water effluents may create fewer problems for IGCC than for direct combustion-based power generation because the steam cycle in an IGCC plant produces less than 40% of the power plant s power. Therefore, the water effluents from boiler feedwater preparation and cooling-water blowdown are significantly less than those for steam < cle-based power generation with direct coal combustion. 

Minimizing steam consumption by using fired heater reboilers will minimize steam plant and boiler feedwater preparation facilities. An alternate approach is to use a hot oil loop where one furnace fires enough heat for all reboilers on the service. 

Plants with CR >70 percent are usually doing a good job of recovering condensate. CR values of <30 percent represent poor performance. Poor condensate recovery is expensive for two reasons. One reason is the energy and chemicals needed to prepare the boiler feedwater. But in recent years, there is a second, more expensive cost associated with poor condensate recovery effluent wastewater treatment. 

The short tube variety is seldom used today except for preparation of boiler feedwater. The kettle-type reboiler is frequently used in chemical plant applications for clean fluids. 

Hydrazine, H2N—NH2, is the simplest diamine. Free hydrazine never has been detected in nature on earth although many hydrazine derivatives have been found. Anhydrous hydrazine was prepared first by Lobry de Bruyn in 1894, In 1938, Fairmont Chemicals began the first production of hydrazine in the United States the quantity produced was small, and the product was mainly for captive use in boiler feedwater treatment. In World War II, hydrazine became important to Germany as a component of missile fuel. In 1954, Olin Chemicals built the first U.S. commercial N2H4 plant, of about 4 million Ib/year capacity. Hydrazine mainly is consumed as a high energy rocket fuel, an oxygen... 

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