Boilers makes steam

Because fuel costs are high, the search is on for processes with higher thermal efficiency and for ways to improve efficiencies of existing processes. One process being emphasized for its high efficiency is the gas turbine combined cycle. The gas turbine exhaust heat makes steam in a waste heat boiler. The steam drives turbines, often used as lielper turbines. References 1, 2, and 3 treat this subject and mention alternate equipment hookups, some in conjunction with coal gasification plants. 

Gas or oil fuel is burned in a furnace or boiler (heat exchanger) to heat air or water, or to make steam that carries the heat absorbed from the combustion process to the rooms in the house, as shovra in Figure 2. This IS accomplished by circulating the warm air through ducts directly to the rooms, or by circulating hot water or steam through pipes to baseboard hot water con-... 

De-ionized water is required for high-pressure boiler make-up and in many chemical process applications. Where a process has a large-scale steam demand, high-pressure turbine generators are often installed to generate power before providing the process with pass-out steam, thus making the most efficient use of the fuel. If the process does not return the steam as condensate, the... 

Oils or fats generally are introduced into the boiler from steam that has been contaminated by an industrial process. Although a high percentage of condensate return usually is a desirable objective, where contamination takes place, the returning condensate transports these contaminants throughout the steam-water system, clearly making a seamless boiler operation much more difficult. 

Water is used in the chrome pigment industry mainly to cool most of the equipment such as heat exchangers, generate steam in the boilers, make slurry of raw materials, scrub the reactor vent... 

The pharmaceutical industry lead the way in adoption of CEDI for the production of ultrapure water. Since the early 1990 s, the power industry has been employing CEDI as a polisher for RO effluent for steam generation. Other industries currently using CEDI include general industry for boiler make-up or high-purity process applications, including semiconductor manufacture. Commercially-available industrial CEDI modules range in size from less than 1 gpm to 80 gpm. 

Figure 8.17 A simplified representation of a power plant steam-water circuit. Legend 1 boiler 2 steam-water drum 3 superheater 4 turbine, high (H), intermediate (I), low (L) pressure 5 reheater 6 generator 7 condenser 8 make-up water treatment plant (MUP) 9 condenser extraction pump(s) 10 condensate polishing water treatment plant (CPP) 11 LP heater(s) 12 deaerator 13 boiler feed pump (s) 14 HP heater(s) 15 economizer...

Methane is burned in a furnace with 100% excess dry air to generate steam in a boiler. Both the air and the methane enter the combustion chamber at 500°F and 1 atm, and the products leave the furnace at 2000°F and 1 atm. If the effluent gases contain only CO2, H2O, O2, and N2, calculate the amount of heat absorbed by the water to make steam per pound of methane burned. 

Furnace cameras are now utilized in fhousands of process indusfry boilers, which make steam to heaf fhe producf being processed. The cameras monitor fhe large fireboxes where air and fuel are mixed for fhe combustion that heats water in drums, tubes, and headers. Viewing inside the boiler, they help reduce pollution and improve safety. Combined with other techniques, cameras can help reduce pollution as much as 30%. 

Fig. 5.16. A waste heat boiler can save much fuel if there is need for steam concurrent with availability of hot flue gases. The need for steam must never be allowed to reduce the positive pressure in the process furnaces supplying the waste heat for making steam. Courtesy of North American Mfg. Co.

Make sure that all statutory requirements and instructions given by inspecting authorities have been complied with. Some of these could be for boilers, economiser, steam lines, and electrical mains which have to be necessarily stopped for thorough cleaning and internal inspections. 

The simplest control scheme is acceptable when fluctuations in the steam rate are minor and when the ratio of water inventory in the boiler to steam production rate is high, making the system less sensitive to fluctuations in demand. The latter is more likely to be true when fire-tube boilers are used. The choice of control system depends on the individual plant characteristics. Chlor-alkali plants tend to have consistent demands for... 

Other significant water uses are boiler water and process water. Boiler water, almost totally evaporated in the boiler to make steam, requires more intensive treatment than cooling water. As a minimum, all of the hardness ions (e.g., calcium and magnesium ions) will be removed. It is common for treatments to remove virtually all dissolved salts from water to be used in boilers, especially high-pressure boilers. 

Steam Instead of using a hot water boiler, a steam boiler or generator is used. The advantages of steam are that the curing time is much faster however, the liner used must have a coating resistant to steam. With some use of other resins, steam curing can also make the finished product stronger that those cured with hot water. 

Boiler feed water (BFW) is used to remove heat from a process stream to make steam that can be... 

An important principle for making steam from acid is that Fig. 24.8 s boiler feed acid should be as hot as possible while ... 

The latter is a particular problem in petrochemical processes that use stainless steel heat exchangers to make steam as a means of recovering waste heat. Any chloride contamination of boiler feedwater can result in chlorides concentrating in heat-exchanger tubes and can cause pitting and SCC. As a rule, austenitic stainless steels are not recommended for components in which water is likely to evaporate or condense out. 

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

Carbon produced by these latter reactions is formed in the catalyst pores, making it much more difficult to remove, and potentially causing physical breakage. Operating steam to carbon ratios are chosen above the minimum required in order to make carbon formation by these reactions thermodynamically impossible (3). Steam is another potential source of contaminants. Chemicals from the boiler feedwater or the cooling system are poisons to the reformer catalyst, so steam quality must be carefully monitored. 

Process condensate from reforming operations is commonly treated by steam stripping. The stripper is operated at a sufficiently high pressure to allow the overhead stripping steam to be used as part of the reformer steam requirement (71). Contaminants removed from the process condensate are reformed to extinction, so disposal to the environment is thereby avoided. This system not only reduces atmospheric emissions, but contributes to the overall efficiency of the process by recovering condensate suitable for boiler feedwater make-up because the process is a net water consumer. 

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