Electrical boiler

There are four fundamental types of boiler available today—electric boilers, fire tube (shell or FT) boilers, water tube (WT) boilers, and nuclear reactor boilers. Electric boilers apart, all other types are essentially developments from shell and tube heat-exchanger designs. 

Mansour, M. N., Jones, D. G., "Emission Characteristics of Paraho Shale Oil as Tested in a Utility Boiler, Electric Power Research Institute Report AF-709, March 1978. 

In gas boilers electricity used for electrically powered gas valves and gas igniters can be neglected. In oil boilers two other important electrical loads have to be taken into account instead electrical resistance used to preheat the oil to the right viscosity and the oil pump consumption for pressurizing and atomizing the fuel. 

Title prEN 15456 2006 Heating boilers. Electrical power consumption for heat. 

Auxiliary Boiler System Auxiliary Boiler (Electric) Condensate Makeup Pumps Feed Pumps and Valves Deaerator... 

Heating, water supply, and power boilers-electric (1991)... 

Notifications for licensing fees, deposits to be made for obtaining power and water connections, and inspections of boilers, electrical installations, and fuel storages are received from statutory authorities and these must be immediately complied with. 

The first requirement is to create a list of all major fire hazards (29 CFR 1910.39). Major fire hazards would consist of the storage of large quantities of combustibles such as paper, heaters, boilers, electrical panels, flammable liquids, ovens, stoves, natural gas lines, utility entry points to the building, and storage of chemicals. 

Exampie A.3.1 The pressures for three steam mains have been set to the conditions given in Table A.l. Medium- and low-pressure steam are generated by expanding high-pressure steam through a steam turbine with an isentropic efficiency of 80 percent. The cost of fuel is 4.00 GJ and the cost of electricity is 0.07 h. Boiler feedwater is available at 100°C with a heat capacity... 

This technology has since been introduced to the fossil power generating industry. To-date, several major utilities including the Termessee Valley Authority, Baltimore Gas and Electric and American Electric Power, as well as many others, have employed this technology to assess the condition of power-generating boiler tubes. 

Humidification. For wiater operation, or for special process requirements, humidification maybe required (see Simultaneous HEAT and mass transfer). Humidification can be effected by an air washer which employs direct water sprays (see Evaporation). Regulation is maintained by cycling the water sprays or by temperature control of the air or water. Where a large humidification capacity is required, an ejector which direcdy mixes air and water in a no22le may be employed. Steam may be used to power the no22le. Live low pressure steam can also be released directly into the air stream. Capillary-type humidifiers employ wetted porous media to provide extended air and water contact. Pan-type humidifiers are employed where the required capacity is small. A water filled pan is located on one side of the air duct. The water is heated electrically or by steam. The use of steam, however, necessitates additional boiler feed water treatment and may add odors to the air stream. Direct use of steam for humidification also requires careful attention to indoor air quahty. 

There has been increased interest in firing wood waste as a supplement to coal in either pulverized coal (PC) or cyclone boilers at 1—5% of heat input. This appHcation has been demonstrated by such electric utilities as Santee-Cooper, Tennessee Valley Authority, Georgia Power, Dehnarva, and Northern States Power. Cofiring wood waste with coal in higher percentages, eg, 10—15% of heat input, in PC and cyclone boilers is being carefully considered by the Electric Power Research Institute (EPRI) and Tennessee Valley Authority (TVA). This practice may have the potential to maximize the thermal efficiency of waste fuel combustion. If this practice becomes widespread, it will offer another avenue for use of fuels from waste. 

The hot gases from the combustor, temperature controlled to 980°C by excess air, are expanded through the gas turbine, driving the air compressor and generating electricity. Sensible heat in the gas turbine exhaust is recovered in a waste heat boiler by generating steam for additional electrical power production. 

Methanol, a clean burning fuel relative to conventional industrial fuels other than natural gas, can be used advantageously in stationary turbines and boilers because of its low flame luminosity and combustion temperature. Low NO emissions and virtually no sulfur or particulate emissions have been observed (83). Methanol is also considered for dual fuel (methanol plus oil or natural gas) combustion power boilers (84) as well as to fuel gas turbines in combined methanol / electric power production plants using coal gasification (85) (see Power generation). 

Some additional methods of classification are under development that center on the use of lignite for combustion in utihty boilers or electric power generation. Correlations based on the sodium concentration in the lignitic ash (10), or soluble A1 concentration (11) are used. The classifications are often given in terms of the severity of boiler fouling. 

A circulating fluidized-bed boiler, using raw shale oil as a feedstock, is being used to supply process heat for the phosphate operations and to operate a 100-MW power plant. Scale-up in the 1990s should increase the electric power generation to 1000 MW (71). 

The overall yield of the process is at least 87 mol %, and 2.3 mol of methanol per mole of final product are needed, an excess of 15% over the 2.0 theoretical amount. The methanol can be recycled from the manufacture of poly(ethylene terephthalate). Reported utilities consumptions per kilogram of product are 1.2 kg of 1400-kPa steam, 420 kj of boiler fuel, and 0.5 kWh of electricity (72). 

In 1991, Goodyear began working with Cadence Environmental Energy (Indiana) to market a whole tine feed system to supplement fuel for cement kilns. The system is used by several cement manufacturers. In 1992, Goodyear furnished tines for a Tennessee Valley Authority (TVA) test bum at a Memphis power plant. The electric utiUty used tine-derived fuel (TDE) to supplement coal fuel in a cyclone boiler. These tests were successflil. 

Hazardous Air Pollutants. Tide 3 of the CAAA of 1990 addresses the release of hazardous air poUutants (HAPs) by requiring both the identification of major stationary sources and area source categories for 189 toxic chemicals and the promulgation of control standards. Major sources of air toxics, also referred to as HAPs, include any stationary source or group of sources emitting 10 or more tons/yr of any single Hsted toxic chemical or 25 tons/yr of a combination of any Hsted toxic. Area sources of HAPs include smaller plants that emit less than the 10 or 20 tons/yr thresholds. The major sources of HAPs are typically industrial faciHties. However, Tide 3 requites the EPA to study potential health affects associated with emissions of HAPs from electric UtiHty boilers (11). 

Another furnace that does not require fuel preparation is the stoker boiler, which was used by New York State Electric Gas Corporation (NYSEG) in its TDE tests. At NYSEG, the stoker boiler, which has a 1649°C (3000°E) flame temperature (as does the cyclone boiler), has routinely blended low quaUty coal, and more recently, wood chips with its standard coal to reduce fuel costs and improve combustion efficiency. In the tire-chip tests, NYSEG burned approximately 1100 t of tire chips (smaller than 5x5 cm) mixed with coal and monitored the emissions. The company determined that the emissions were similar to those from burning coal alone. In a second test-bum of 1900 t of TDE, magnetic separation equipment removed metal from the resulting ash, so that it could be recycled as a winter traction agent for roadways. 

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