Steam boiler system

Monobutylamines are easily soluble in water and hydrocarbons and can generally be steam distilled. These properties lead to uses in soaps for water and oil emulsions, and as corrosion inhibitors in steam boiler appHcations (see Corrosion and corrosion inhibitors Emulsions). Morpholine is also extensively used as a corrosion inhibitor in steam boiler systems. In addition, it is widely used as an intermediate in the production of delayed-action mbber accelerators. 

In LP steam boiler systems, this problem of uncontrolled or excessive water or condensate return loss also occurs. It may be uncontrolled perhaps because of leaking steam traps or excessive as a result of too frequent or prolonged BD. Irrespective of the basic cause, it is necessary to obtain an accurate assessment of materials balance as a first step in understanding the magnitude of the problem and providing resolution. 

Anodic inhibitor programs These programs are based on ingredients such as nitrite, silicate, and molybdate chemistries and usually are formulated as light-duty multifunctional programs in HW heating and LP steam boiler systems. 

The potential for electrochemical corrosion in a boiler results from an inherent thermodynamic instability, with the most common corrosion processes occurring at the boiler metal surface and the metal-BW interface (Helmholtz double layer). These processes may be controlled relatively easily in smaller and simpler design boilers (such as dual-temperature, LPHW heating, and LP steam boiler systems) by the use of various anodic inhibitors. 

Morpholine is a solvent and intermediate for optical brighteners and rubber chemicals. It is also a corrosion inhibitor, especially in steam boiler systems. Some other uses include ... 

The previously feared caustic embrittlement of steel boilers has practically vanished after the introduction of high purity, i.e. deionised water [60]. Low carbon steels are sufficient for those sections of the steam boiler which come into contact with liquid water less than 330 °C. For the hot side of turbines a steel with 12% Cr is recommended. The remaining sections of the steam boiler system consist of carbon steel or low alloyed steel [22]. Steam boiler operation in the super heater section (500-600 °C) affects the diffusion of hydrogen in the steel, and will thereby be dec-arburised [14]. The methane that is formed caimot escape from the iron, stresses are formed and the formation of cracks and blisters occurs. A remedy was found by adding 0.5% Mo and 1% Cr, whose carbides at boiler temperature do not transform into methane [14, 61]. The limit of the use of these steels is portrayed in Figure 7. 

The process requires (Qup + Qlp) to satisfy its enthalpy imbalance above the pinch. If there were no losses from the boiler, then fuel W would be converted to shaftwork W at 100 percent efficiency. However, the boiler losses Qloss reduce this to below 100 percent conversion. In practice, in addition to the boiler losses, there also can be significant losses from the steam distribution system. Figure 6.336 shows how the grand composite curve can be used to size steam turbine cycles. ... 

Utility systems as sources of waste. The principal sources of utility waste are associated with hot utilities (including cogeneration systems) and cold utilities. Furnaces, steam boilers, gas turbines, and diesel engines all produce waste from products of combustion. The principal problem here is the emission of carbon dioxide, oxides of sulfur and nitrogen, and particulates (metal oxides, unbumt... 

Fig. 25. Schematic of large fossil steam turbine system where BFPT = boiler feed pump turbine. To convert MPa to psi, multiply by 145.

AH vapors, including hotweH odors, are captured in a header system linked with the incineration air of a steam boiler or hot oil vaporizer. Drain seals avoid escape of odors from the sewer lines. This completely eliminates total reduced sulfur (TRS) emissions. The SO2 emissions are subject to local regulations. 

The quahty of feed water required depends on boiler operating pressure, design, heat transfer rates, and steam use. Most boiler systems have sodium zeohte softened or demineralized makeup water. Feed-water hardness usually ranges from 0.01 to 2.0 ppm, but even water of this purity does not provide deposit-free operation. Therefore, good internal boiler water treatment programs are necessary. 

Linked characterized valves. The relationship between angular rotation of the valve spindle and open area of the valve can be adjusted over different portions of the flow range using a series of screws. In this way, the air/gas ratio can be characterized to any desired profile over the whole firing range. These valves are suited to fully modulating systems and are commonly used on steam boilers. 

With hot water units, time clock control can operate satisfactorily as automatic bypass valves built into the distribution system will help the heater to achieve its working temperature quickly. With steam boilers, it is important that the boiler reaches a reasonable working pressure before steam is allowed into the distribution system. For example, if boilers are left open to a system for an extended length of time while not firing they will quickly lose their pressure. This is not only wasteful of energy but eventually creates a problem on start-up. To... 

Condensate returns lines are often copper. Copper has good corrosion resistance to oxygen and carbon dioxide individually. When both gases are present in the condensate, copper is susceptible to corrosion. Copper picked up in the condensate system and returned to the boiler causes serious corrosion problems in the boiler and any steel feedwater and steam pipework. Boiler tubes should last for 25 years but can fail within one year in a mismanaged or ill-designed boiler system suffering from these faults. 

Permits to work can be of differing formats. Therefore, it is essential that when a permit to work has been issued it should be read carefully and understood and all possible measures taken to reduce or eliminate the known danger. Permits can be issued for a variety of work tasks (e.g. work on high-voltage electrical systems, steam boilers, hot work, confined spaces, etc.). The permit below is an example of differing types of work tasks. 

The importance of magnesium chloride has probably been exaggerated. There is little doubt that it can act as a catalyst in corrosion reactions by hydrolysing to form hydrochloric acid, being then regenerated by reaction between ferrous chloride and magnesium hydroxide. There is, however, little evidence that this reaction takes place in cold- or hot-water systems, and it is probably confined to steam boilers where it might be a cause of corrosive attack underneath scale deposits it does not constitute a problem in a properly conditioned boiler water. 

Condensate purification In some boiler systems the condensate returning is retreated using ion exchange to minimise corrosion and deposit accumulation. This particularly applies to once-through boilers (mainly nuclear) where there may be no water/steam separator and perhaps limited facilities for blow-down. Additionally, some high heat-flux boilers (oil-fired) have been fitted with condensate polishing plant (CPP). 

Traps that stick open may allow considerable volumes of steam to blow through, thus resulting in a reduction in overall boiler system efficiency. 

For most larger industrial applications around the world, either FT or WT boilers are generally employed. Design permutations are considerable, and many factories have both types installed, feeding into separate steam distribution systems (typically at different pressures) or a common steam header. A discussion on the various types of boilers follows ... 

In common with a FT boiler plant, a WT boiler plant contains several steam-water condensate systems and subsystems, although those of industrial and waste-heat WT boiler systems are generally larger and more complex, and power WT boiler systems are even more so. 

Within the boiler, subsystems include a steam-water circulation system and a steam delivery system. 

The boiler steam-water circulation system is designed to promote the delivery of steam from the various generating tubes to the boiler steam drum (top drum). From here the steam is separated from the BW and transferred to the steam delivery system for possible superheating and subsequent use in a turbine generator or other downstream process application. 

Combined Cycle Boiler Systems These boiler types are used to harness the waste heat from one power source to provide the heat source for a second power source, usually an electricity generator via a steam turbine. They are a form of cogeneration boiler plant. 

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