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Operating Wisely
Published in Carl Bozzuto, Boiler Operator's Handbook, 2021
In power plants where the steam is primarily used to generate power, the steam and water cycle becomes more complex. Some of these are referred to as supercritical boiler plants because the steam is generated at pressures exceeding 3190 psig where the density of water and steam are the same. Density is simply a value representing the weight of a substance in pounds per cubic foot. Because there is no difference in density, those boilers do not have a level indicator or gauge glass as there is no water level. After the water is converted to steam in the boiler, it passes through the superheater, more tubes exposed to the boiler flue gases or radiant heat from the fire where it is heated further, thus increasing its temperature. Steam heated to temperatures higher than the saturation temperature is superheated steam. The superheated steam is piped to a steam turbine or steam engine where the energy in the steam is converted to power. The conversion of energy to create power is associated with a drop in steam pressure and temperature. Each horsepower of mechanical energy is produced by removing 2545.1 Btu per hour from the steam plus an allowance for losses due to inefficiency.
Test Your Understanding
Published in Sandeep Misra, Chandana Roy, Anandarup Mukherjee, Introduction to Industrial Internet of Things and Industry 4.0, 2021
Sandeep Misra, Chandana Roy, Anandarup Mukherjee
In a thermal power plant, the heat energy is converted to electric power. The water is heated in the boiler and passed through the superheater to convert the saturated steam into superheated steam. Further, this superheated steam is used in steam turbines for generation of electricity. Suppose, a turbine rotates at 7200 RPM. Compute the average rotational latency of the turbine.Different type of sensor nodes are deployed at various locations in the plant. If each sensor node consumes energy of 0.012 mW-h and initial energy is 0.5 J, find the average power consumed per day for 1080 nodes in that unit. Also estimate the average yearly power consumption based on the type of sensor nodes, in the year 2024 (Table 18.5).
Steam and Condensate Systems
Published in Stephen A. Roosa, Steve Doty, Wayne C. Turner, Energy Management Handbook, 2020
Saturated and superheated steam. If we put cold water into a boiler and heat it, its temperature will begin to rise until it reaches the boiling point. If we continue to heat the water, rather than continuing to rise in temperature, it begins to boil and produce steam. If the pressure remains constant, the temperature will remain at the saturation temperature for the given pressure. The more heat added, the more liquid will be converted to steam. We call this boiling liquid a saturated liquid and refer to the steam so generated as saturated vapor. Continuing to add more heat will generate more saturated vapor (or simply saturated steam) until the water is completely boiled away. At this point, if we continue to add heat, the steam temperature will begin to rise once more. We call this superheated steam. This chapter concentrates on the behavior of saturated steam, because it is the steam condition most commonly encountered in industrial process heating applications. Superheated steam is common in power generation and is often produced in industrial systems when cogenerating power and process heat.
Computational modeling of spatial variation in moisture content and temperature distribution in corn at different superheated steam temperatures
Published in Cogent Engineering, 2023
Mercy Jepchirchir Kimwa, Nancy Karuri, Josephat Tanui
Superheated steam dryers are commonly used in high moisture applications because they have 50% higher drying efficiencies compared to conventional drying systems (Mujumdar, 1995; Pronyk et al., 2004). Superheated steam has higher thermal conductivity and the heat capacity compared to air resulting in higher drying rates in superheated steam driers. Danilov and Leonchik (1967) showed that drying with superheated steam accelerates the drying process, making it economical and efficient at atmospheric pressure. Grain drying using superheated steam reduced the drying period compared to conventional dryers. Low-pressure superheated steam dryers are operated below atmospheric pressures in the range of 5–30 kPa (Chou & Chua, 2001). Since low-pressure steam dryers operate at lower pressure levels they have poor convective heat transfer and uneven drying and thus the drying process under these conditions is ineffective and inefficient (Devahastin et al., 2004;).
A comprehensive review of recent advances in renewable-based drying technologies for a sustainable future
Published in Drying Technology, 2022
Canan Acar, Ibrahim Dincer, Arun Mujumdar
In superheated steam drying, the heat from the steam, which is at a temperature above its boiling point and absolute pressure, is utilized. Superheated steam drying is an innovative technology and a promising alternative to traditional drying systems. In the literature, it is demonstrated that superheated steam drying is an efficient and environmentally benign alternative to hot air-based drying at similar operating conditions.[60] Superheated steam dryers generally operate at low pressures to reduce the boiling temperature of the water in the product. As a result of low operating pressures, the moisture within the product can evaporate at much lower temperatures compared to drying ambient pressures. Therefore, superheated steam dryers can operate at higher efficiencies at low operating temperatures. Furthermore, because of the low operating temperatures, superheated dryers are suitable for products that have heat-sensitive content. Some of the other advantages of superheated steam are no oxidative reactions as well as the preservation of color, quality, texture, and nutrients.[76]
Investigation of the thermodynamic behavior of an apple juice waste- and sugarcane bagasse-fuelled combined-cycle power generation system
Published in Biofuels, 2020
Figure 1 shows a thermochemical model of the biomass gasification combined power cycle. The sugarcane bagasse and apple juice waste are fed to the gasifier at stage 3. The compressed air at stage 2 and pressurized saturated steam at stage 4 enter the gasifer where syngas is produced and go to the combustion chamber (CC) at stage 5 after passing through a gas cleanup unit. In the CC chemical reactions take place and products of combustion go to the gas turbine (GT) at stage 6, expand and produce power. The exhaust gasses of the GT enter the heat recovery steam generator (HRSG) at stage 7 where superheated steam is produced. This superheated steam is used to run the steam turbine (ST) and produce electric power. The exhaust steam from the ST is then routed to the condenser where its phase changes from vapour to liquid water, and this water is pumped back to the HRSG. The waste hot gases exiting from the HRSG discharge to the atmosphere at ambient pressure and 400 K temperature, at stage 8 [16].