Steam boilers draft

Although the engine was not a success, Ericsson s trip to London allowed him to meet John Braithwaite, a machine manufacturer, who had the expertise to put Ericsson s ideas into practice. In 1828 Ericsson, with Braithwaite, patented the principle of artificial draft in steam boilers. The principle of forced draft was applied to a fire engine and a locomotive entered for the Rainhill locomotive trials of 1829. 

Converters with indirect cooling have been known since the early days of ammonia production, for example, the Fauser-Montecatini reactor [843], [844], [848], [867], [891]-[893], In this converter, tube coils between catalyst beds transfer the reaction heat to a closed hot water cycle under pressure, operating by natural draft. The hot water releases the absorbed heat in an external steam boiler generating about 0.8 t of steam per tonne of ammonia at about 45 bar (ca. 250 °C). 

Fig. 1. Typical heater configuration. BFW = boiler feed water SSH = super high pressure steam HP = high pressure and ID = induced draft..

Modern SM boilers are widely used for hydronic heating, LP steam applications, and some HP processes. They are available in forced-draft gas, oil, and combination fuel modes, typically producing up to 1,200 hp (41,400 lb/hr). U.S. manufacturers today build to a 5 sq ft of heating surface per hp standard (6,700 Btu/hr/sq ft). 

Legend 1 = steam header, 2 = steam drum, 3 = attemperator, 4 = superheater, 5 = top header, 6 = riser and downcomer (note downcomer is outside the boiler), 7 = bottom header, 8 = water wall tube membrane (with radiant area inside membrane), 9 = burners, 10 = mud dmm, 11= boiler bank, 12 = economizer, 13 = dust collector, 14 = forced draft fan, 15 = air-heater, 16 = induced draft fan, 17 = stack... 

Soot blowers also are used to clean particular boiler tube bundles, such as superheaters and economizers. Steam or compressed air normally is used, and operating practice may require the use of manual boiler control and increased furnace draft or boiler loading during sootblowing periods to avoid the risks of loss of furnace flame (flameout) or small furnace explosions (furnace puff). 

Consider a forced-draft boiler producing 600-psig steam as shown in Fig. 20.2. The fuel rate on this boiler is fixed and we are going to optimize the oxygen (02) content of the flue gas by adjusting the speed of the forced-draft fan. Do we simply adjust the forced-draft (FD) fan to give 2 percent 02 in the stack because someone once said that 2 percent 02 in the stack was a good number ... 

The Oregon installation uses a 25 tire per hour unit manufactured by Nippo in Japan and marketed in the U.S. by Tsurusaki Sealand. The unit has been in operation since 1987 with moderate success, but no U.S. company has yet decided to purchase another one. The draft configuration in the unit allows it to bum at 2,000 degrees Fahrenheit and produce 100 psig process steam. The unit has a Cleaver Brooks waste heat recovery boiler and a bag filter. Whole tires are automatically fed into the unit-both automobile tires and light truck tires. The State of Oregon Department of Environmental Quality has approved the operation of the unit. 

Steam systems. An investment cost of 35 per lb/h of total steam generation capacity is recommended for preliminary estimates (costs as of 2001). This represents the total installed costs for gas- or oil-fired, forced-draft boilers operating at 250 to 300 psig, and all appurtenant items such as water treating, deaerating, feed pumps, yard piping for steam, and condensate. 

Figure 105. Modern integrated single-train ammonia plant based on steam reforming of natural gas (Clide process) a) Sulfur removal b) Primary reformer c) Steam superheater d) Secondary reformer e) Waste heat boiler f) Convection section g) Forced draft fan h) Induced draft fan i) Stack k) TIT and LT shift converters ...

Mechanical draft may be afforded by a steam jet, by blast fans (forced draft) discharging to the ashpit, or by suction fans (induced draft) placed between the boiler and the short stack. Steam jets, whether of the suction or pressure type, are wasteful of steam, though cheap to install. They will not give very high drafts, but tend to prevent clinkering. 

Three Lancashire boilers were installed, although only two were ever in steam at one time, thus allowing for a programme of preventative maintenance. Throughout the war there had always been a shortfall in the supply of new boilers caused by a shortage of skilled boilermakers, most of whom had been drafted into the shipyards in the early war years. 

Greene s investigation found that there were insufficient staff to run and maintain the plant properly in particular care was not being taken to ensure that fiue gas and boiler water analysis were carried out despite the presence of suitable monitoring instruments. Both boilerhouses were fitted with CO2 recorders, 5-point temperature recorders, integrating steam-flow indicators and draft recorders, but most of this equipment was either disconnected or so badly calibrated as to be useless. 

In another process plant, the steam system operates with a large amount of LP vent. To prevent loss of valuable condensate due to LP vent, a condenser was installed to cool down the LP steam and return LP condensate back to the deaerator. Although this solution saves condensate, it did not resolve the LP long issue. It was later identified that a driver switch could help to reduce the LP vent In the boiler house, there are three forced draft (FD) fans currently run by MP-LP extraction turbines but fans have spare motor drivers. The operation policy acceptable to the plant was to use steam turbines for reliability reasons. The engineer wanted to establish the value of the driver switch to minimize the LP dump. 

There are three boiler forced draft (FD) fans, which are run by medium-pressme to low-pressure (MP-LP) extraction turbines currently with motors in spare. It was identified that motor driving is more economical than turbine due to relatively low electricity price. Based on steam marginal pricing, it is estimated that if one fan can be switched to motor, the benefit would be 738,144 per year. The cost savings would be 2.2MM/year if three fans could be switched to motors. 

At the Tenneco Oil Refinery in New Orleans, 1 first learned how to optimize the excess oxygen content of the flue gas from a boiler. The fired boiler was equipped with a forced-draft (FD) fan. Due to mechanical deficiencies of the FD blower, the combustion air supply was limited, but constant. The boiler produced 650-psig steam, which was in short supply in the refinery. Flence, the boiler was operated to maximize steam production. 

Figure A1.5 Typical scheme of coal-fired thermal power plant (AuthorAJser BillC https // commons.wikimedia.org/wiki/File PowerStation2.svg website approached January 26, 2016) (1) Cooling tower (2) cooling-water pump (3) transmission line (3-phase) (4) step-up transformer (3-phase) (5) electrical generator (3-phase) (6) low-pressure (LP) steam turbine (7) condensate pump (8) surface condenser (9) intermediate-pressure steam turbine (10) steam control valve (11) high-pressure (HP) steam turbine (12) deaerator (13) feedwater heater (14) coal conveyor (15) coal hopper (16) coal pulverizer (17) boiler steam drum (18) bottom ash hopper (19) superheater (20) forced draught (draft) fan (21) reheater (22) combustion air intake (23) economizer (24) air preheater (25) precipitator (26) induced-draught fan and (27) flue gas stack.

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