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Water Treatment
Published in Kenneth E. Heselton, Boiler Operator’s Handbook, 2020
Deaerators are provided in five types, vacuum, flash, spray, scrubber, and tray. A vacuum deaerator is typically a vessel filled with packing and operated under a vacuum. The packing is not like pump or valve packing, it’s like fill, loose pieces of ceramic or plastic materials stacked randomly that act sort of like splash blocks so a lot of the water surface is exposed as it tumbles down through the packing. Producing a sufficient vacuum in a vacuum deaerator will bring the water to a saturated condition. For example, pulling a vacuum of 29”Hg (inches of mercury) produces a condition where 79°F water will boil. As long as the water is warmer than the saturation temperature that matches the pressure inside the deaerator it will be at boiling and a little is actually vaporized. The air and noncondensable gases are removed from the deaerator by the vacuum pump or steam jet ejector, whichever is used. A steam jet ejector will normally discharge to a condenser that uses the remaining energy in the steam to preheat the water before it enters the deaerator. When a vacuum pump is used provisions are made to heat the water and can include any type of heat.
Balance of Plant
Published in S. Can Gülen, Gas Turbine Combined Cycle Power Plants, 2019
The deaerator is a direct-contact feedwater heater that heats the boiler feedwater and removes the dissolved O2 and CO2. Heating and scrubbing functions are accomplished by utilizing steam from a steam turbine extraction point or from the HRSG. There are two types of deaerators: spray and tray types. In the spray deaerator, a jet of steam mixes thoroughly with the condensate that is sprayed into the unit. In the tray type, the condensate coming in falls over a series of trays, where it disintegrates into small droplets and mixes with steam. The more common type used in power plants is the tray type.
Water Treatment
Published in Carl Bozzuto, Boiler Operator's Handbook, 2021
Water is treated for two principal reasons: to prevent corrosion and to prevent scale formation. The most common form of corrosion is destruction of the metal by hydrogen ions. However, other chemicals dissolved in water can also attack the metal. Another form of corrosion is oxidation, where the oxygen in the air or water combines with the metal to form rust. A severe form of oxygen corrosion is oxygen pitting. The deaerator is the device that serves to remove dissolved oxygen from the boiler water.
Ambient conditions impact on combined cycle gas turbine power plant performance
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2023
Alaa Ahmad Sammour, Oleg V. Komarov, Mohammed A. Qasim, Samair Almalghouj, Ali Mazen Al Dakkak, Yang Du
The dual pressure HRSG employed in the Jandar Power Plant consists of a series of heat exchangers, particularly, an economizer, evaporator and a superheater for the HP level. It also has three further heat exchangers including a preheater, economizer, and evaporator for the LP level (Figure 3). Economizers are utilized to heat water to nearly the saturation point. Evaporators generate saturated steam and superheaters produce superheated steam. A good way to illustrate the fundamental thermodynamics of an HRSG is to examine the “heat release” diagram shown in Figure 4 In this diagram, the horizontal axis represents heat transfer. The vertical axis represents steam and gas temperatures in the “heat release” diagram. Flue gases enter at temperature, T1g, and pass through various sections in the dual pressure HRSG, finally leaving at T7g. Feed water is pumped from a condensate tank (State 19) to the preheater section of the HRSG (State 20), where the condensate is heated at constant pressure from Tw1 to Tw2. The water is then directed to the deaerator. A deaerator is a mechanical device that reduces dissolved gases from the boiler water, especially oxygen and carbon dioxide, to a low level. After that, the feed water is divided into HP and LP streams. The LP boiler feed-water pumps (LP BFP) deliver feed water to the LP section, in particular, to the economizer section. Here, the feed water is heated from Tw2 to a saturated state at Tw3. Eventually, the feed water enters the evaporator to generate LP steam. The fluid flow in the evaporator is a forced circulation by a boiler-circulated pump (BCP) for each pressure level. Steam drums are used to separate the water and steam leaving the evaporator.
Energy efficiency in steam using industries in Greece
Published in International Journal of Sustainable Energy, 2020
Ifigenia Farrou, Andreas Androutsopoulos, Aristotelis Botzios-Valaskakis, Georges Goumas, Charilaos Andreosatos, Loukas Gavriil, Christoforos Perakis
On its own, the installation of a retrofit de-aerator to the condensate tank, as well as a flash steam recovery blowdown vessel would only lead to small fuel savings of approximately 1%. However, one must also take into account the added-value benefits of the reduction of costs for the purchase of chemical agents used today for the deaeration of the make-up water. The deaerator performs several functions the most important ones include removing dissolved oxygen from the feedwater, preheating the make-up water, serving as a storage tank for feedwater and supplying the boiler feedwater pump.
Optimization models for operation of a steam power system in integrated iron and steel works
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2021
Qi Zhang, Tao Zhao, Tuanjie Ni, Jintong Gao
The role of the deaerator is to remove the water soluble oxygen or other non-condensable gas in boiler water lest excessive corrosion of the boiler and steam turbine. In this unit, the inlet streams may come from low-pressure steam, condensate return from process or treated water makeup. After water is treated and its dissolved gas is removed, the feed water is directed to boilers or let-down stations.