These tutorials explain the principles of steam engineering and heat transfer. They also provide a comprehensive engineering best practice guide covering all aspects of steam and condensate systems; from the boiler house and steam distribution system up to the point of use; through the condensate recovery system and returning to the boiler. Virtually all major applications and products are discussed.
The steam and condensate loop explained How steam is generated, and why factors like feedwater, level control, and blowdown matter. Discover how steam gets to where it is needed, and why steam quality is important.
An overview of the different types of level control systems used, with particular focus on float and solid probe types, most commonly used in the steam and condensate loop. There is a focus on conductivity and capacitance level controls.
The main job of a steam trap is to remove condensate, air, and any noncondensable gases from a steam system whilst minimising the escape of live steam. Here we look at why this is necessary, how they do this, their basic operation, and the standards applied to steam traps.
These use the different densities between steam and water (condensate) to operate. There are two main types: the ball float trap, and the inverted bucket trap. Able to remove large volumes of condensate, mechanical steam traps are used in a wide range of process applications. Discover how each works, and their advantages and disadvantages.
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In industrial steam systems the condensate pump is used to collect and return condensate from remote areas of the plant. The steam produced in the boiler can heat equipment and processes a considerable distance away. Once steam is used it turns to hot water or condensate. This pump and possibly many more around the plant returns this hot water back to a make-up tank closer to the boiler, where it can be reclaimed, chemically treated, and reused, in the boiler, consequently it can sometimes be referred to as a condensate return pump.
In a steam power plant, particularly shipboard ones, the condensate pump is normally located adjacent to the main condenser hotwell often directly below it. This pump sends the water to a make-up tank closer to the steam generator or boiler. If the tank is also designed to remove dissolved oxygen from the condensate, it is known as a deaereating feed tank (DFT). The output of the DFT supplies the feed booster pump which, in turn, supplies the feedwater pump which returns the feedwater to the boiler so the cycle can start over. Two pumps in succession are used to provide sufficient net positive suction head to prevent cavitation and the subsequent damage associated with it.
This pump is usually associated with a much larger tank, float switch, and an electric motor than the example above. Some systems are so remote that steam power is used to return the condensate where electricity is impractical to provide.
If the outlet of the line is at a higher level than the tank of the pump, a check valve is often fitted at the outlet of the pump so that liquid cannot flow backwards into the pump's tank. If the outlet is below the tank level, siphonage usually naturally clears the output line of all liquid when the pump is deenergized. In cold regions of the world, it is important that condensate lines that are exhausted outside be carefully designed so that no water can remain in the line to freeze up; this would block the line from further operation.
Condensate water is distilled water but often contains chemicals. If it is being condensed from an air stream, it may have dust, microbes, or other contaminants in it. If it is condensed from steam, it may have traces of the various boiler water treatment chemicals. And if it is condensed from furnace exhaust gases, it may be acidic, containing sulfuric acid or nitric acid as a result of sulfur and nitrogen dioxides in the exhaust gas stream. Steam and exhaust condensate is usually hot. These various factors may combine (along with local regulations) to require careful handling or even chemical treatment of the condensate, and condensate pumps used for these services must be appropriately designed.
Condensate pumps have been involved in industrial accidents. In one case, a 2,600 gallon per minute steam condensate pump exploded when it was operated with its suction and discharge valves closed. The force of the explosion was such that it propelled a 5 pound (2.2 kg) piece of metal casing over 400 ft. (122 m) away from the site of the explosion.
Abstract:Steam is commonly used for heating in industrial production and transmitted through the steam network. Along with the decarbonization of energy generation and utilization, electric boiler and combined heat and power (CHP) became the alternatives for steam generation. Thus, the steam network is becoming tightly coupled with the power system, which brings new challenges in the simulation and operation of the combined electric and steam system (CESS). A novel simulation approach for CESS that can balance both the simulation accuracy and speed is proposed. Piecewise linearization of the saturated steam property is used for model simplification, which accelerates the simulation speed while ensuring the accuracy. Meanwhile, the heat loss of the steam network takes both condensate loss and heat dissipation into account, which further improves the accuracy of heat loss calculation. In view of model solving, two computation frameworks are provided for back-pressure and extraction condensing the CHP units, respectively. The accuracy and efficiency of the steam heating network model is verified through both the tree and ring steam network. In addition, a CESS case with both CHP and electric boilers is presented, and the results indicate such a system can reasonably improve the system stability and renewable energy consumption capability.Keywords: combined electric and steam system; combined electric and heat system; simulation; steady-state model; condensate loss 2b1af7f3a8