Boilers steam

Having removed the suspended solids and dissolved salts, the water then needs to have the dissolved gases removed, principally, oxygen and carbon dioxide, which would otherwise cause corrosion in the steam boiler. The usual method to achieve this is deaeration, which removes dissolved gases by raising the water temperature1,2. 

The deaerated treated boiler feedwater then enters the boiler. Evaporation takes place in the boiler and the steam generated is fed to the steam system. Solids not removed by the boiler feedwater treatment build up in the boiler, along with products of corrosion. These are removed from the boiler by taking a blowdown (purge) from the boiler. The steam from the boiler goes to the 

There are many types of steam boilers, depending on the steam pressure, steam output and fuel type3. Pressures are normally of the following order. 

As with furnaces, discussed in Chapter 15, the draft in boilers can be natural, forced draft or induced draft. Forced and induced draft arrangements are the most common. For large boilers requiring a significant amount of equipment in the flue to treat the exhaust gases to remove oxides of sulfur and/or oxides of nitrogen, as well as equipment for heat recovery, a combination of forced and induced draft might need to be used. 

As discussed under boiler feedwater treatment, boiler blowdown is required to prevent the build up of solids in the boiler that would otherwise cause fouling and corrosion in the boiler. Carry over of solids from the boiler to the steam system via tiny water droplets should also be avoided. Total dissolved solids (TDS) and silica (SiC 2), as measured by the conductivity of water, are both important to be controlled in the boiler3. Dissolved solids carried over from the boiler will be a problem to all components of the steam system. Silica is a particular problem because of its damaging effect on steam turbines, particularly the low-pressure section of steam turbines where some condensation can occur. Blowdown 

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The principal sources of utility waste are associated with hot utilities (including cogeneration) and cold utilities. Furnaces, steam boilers, gas turbines, and diesel engines all produce waste as gaseous c bustion products. These combustion products contain carbon... 

Energy efficiency of the process. If the process requires a furnace or steam boiler to provide a hot utility, then any excessive use of the hot utility will produce excessive utility waste through excessive generation of CO2, NO, SO, particulates, etc. Improved heat recovery will reduce the overall demand for utilities and hence reduce utility waste. 

Fuel switch. The choice of fuel used in furnaces and steam boilers has a major effect on the gaseous utility waste from products of combustion. For example, a switch from coal to natural gas in a steam boiler can lead to a reduction in carbon dioxide emissions of typically 40 percent for the same heat released. This results from the lower carbon content of natural gas. In addition, it is likely that a switch from coal to natural gas also will lead to a considerable reduction in both SO, and NO, emissions, as we shall discuss later. 

Reducing products of combustion from furnaces, steam boilers, and gas turbines by making the process more energy efficient through improved heat recovery. 

One advantage of anaerobic reactions is that the methane produced can be a useful source of energy. This can be fed to steam boilers or burnt in a heat engine to produce power. 

C its solubihtyis only 14-15 mg/L. As the temperature increases, so does the solubihty until at 100°C solubihty reaches 30-40 mg/L. This faint solubility at elevated temperatures accounts for the accretion of a primarily CaCO scale in steam boilers. Carbon dioxide exerts a mild solvent action on... 

Although the principal appHcation of reverse osmosis membranes is still desalination of brackish water or seawater to provide drinking water, a significant market is production of ultrapure water. Such water is used in steam boilers or in the electronics industry, where huge amounts of extremely pure water with a total salt concentration significantly below 1 ppm are required to wash siUcon wafers. 

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. 

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. 

Metal Cleaning. Citric acid, partially neutralized to - pH 3.5 with ammonia or triethanolamine, is used to clean metal oxides from the water side of steam boilers and nuclear reactors with a two-step single fill operation (104—122). The resulting surface is clean and passivated. This process has a low corrosion rate and is used for both pre-operational mill scale removal and operational cleaning to restore heat-transfer efficiency. 

For some applications, either steam or electricity is simply not available and this makes the decision. It is rarely economic to install a steam boiler just for tracing. Steam tracing is generally considered only when a boiler already exists or is going to be installed for some other primary purpose. Additional electric capacity can be provided in most situations for reasonable costs. It is considerably more expensive to supply steam from a long distance than it is to provide electricity. Unless steam is available close to the pipes being traced, the automatic choice is usually electric tracing. 

Unfired steam boilers with design pressures exceeding 345 kPa (50 Ibftin") have restrictive rules on weided-joint design, and all butt joints require full radiography. 

TABLE 25-68 Energy Output and Efficiency for 1000 Metric Ton of Waste/Day Steam-Boiler Turbine-Generator Energy-Recovery Plant Using Unprocessed Industrial Solid Wastes with Energy Content of 12,000 kJ/kg... 

All sorts of accidents (the sudden collapsing of bridges, sudden explosion of steam boilers) have occurred - and still do - due to this effect. In all cases, the critical stress - above which enough energy is available to provide the tearing energy needed to... 

In many applications a pressure vessel may be tested for safety simply by hydraulic testing to a pressure that is higher - typically 1.5 to 2 times higher - than the normal operating pressure. Steam boilers (Fig. 16.7) are tested in this way, usually once a year. If failure does not occur at twice the working pressure, then the normal operating stress is at most one-half that required to produce fast fracture. If failure does occur under... 

Fig. 4.3. The flat plates that make up the firebox of a model steam boiler ore tied together with screwed stays. To make the threads pressure-tight they must be sealed with solder.

Let s consider an industrial boiler. You may need at least three of these previous mentioned o-rings just to prevent leaks and drips in a simple hydronie or steam boiler. Raw water comes into the boiler room with pipes, gauges, valves and instrumentation. All these fittings would probably use Nitrile rubber o-ring seals to give long-term leak free service. 

To protect steam boilers and their tubes from corrosion, E. Cumberland used cathodic impressed current in America in 1905. Figure 1-10 has been taken from the corresponding German patent [35]. In 1924 several locomotives of the Chicago Railroad Company were provided with cathodic protection to prevent boiler corrosion. Where previously the heating tubes of steam boilers had to be renewed every 9 months, the costs fell sharply after the introduction of the electrolytic... 

Steam engines and steam turbines require steam boilers, which, until the advent of the nuclear reactor, were fired by vegetable or fossil fuels. During most of the nineteenth century, coal was the principal fuel, although some oil was used for steam generation late in the century. 

For some applieations, either steam or eleetrieity is simply not available and this makes the deeision. It is rarely eeonomie to install a steam boiler... 

The ASME code provides the basic requirements for over-pressure protection. Section I, Power Boilers, covers fired and unfired steam boilers. All other vessels including exchanger shells and similar pressure containing equipment fall under Section VIII, Pressure Vessels. API RP 520 and lesser API documents supplement the ASME code. These codes specify allowable accumulation, which is the difference between relieving pressure at which the valve reaches full rated flow and set pressure at which the valve starts to open. Accumulation is expressed as percentage of set pressure in Table 1. The articles by Rearick and Isqacs are used throughout this section. 

The Hartford Steam Boiler Inspection and Insurance Company Center for Chemical Process Safety United States Department of Energy Arthur D. Little, Inc. 

The original steam generators were simple pressure vessels that were prone to caiasirophic failures and loss of life. Due to better boiler design, tube-fired boilers, and boiler inspections, the incidence of catastrophic failure is now to a rare event (about once every 100,000 vessel-years). In Great Britain in 1866, there were 74 steam boiler explosions causing 77 deaths. This was reduced to 17 explo.sions and 8 deaths in 1900 as a result of inspections performed by the Manchester Steam User Association. In the United States, the American Society of Mechanical Engineers established the ASME Pressure Ves.sel Codes with comparable reductions. 

Priming The carryover of particles of water or other fluid in gas flow, mainly in steam boilers. 

Hartford Steam Boiler Inspection and Insurance Co. Hartford, CT... 

Engine failures over a five year span for 138 emergency generators are listed. Discussion of each type of failure is presented. Data listed includes percentage of failure over the population and time period. All failures were presumably insured by Hartford Steam Boiler and subject to functional inspections and audits. 

Dampfkessel, m. steam boiler, -anlage, /. steam boiler plant, steam plant, -beklei-dung, /. boiler covering or casing, -blech, n. boiler plate, -kohle, /. steam coal, -spei-stmg, /. steam boiler feed. 

Wasseidampf, m, water vapor, steam, -bad, n, steam bath (Afed.) vapor bath, -destil-lation, /. distillation with steam, -entwick-ler, -erzeuger, m, (steam) boiler, -gehalt, m, steam content. 

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