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Boiler Plant Operations
Published in Carl Bozzuto, Boiler Operator's Handbook, 2021
Some feel that a blowdown heat recovery system cannot be justified economically. That is usually an incomplete evaluation. If there is no blowdown heat recovery system, then valuable resources are being wasted. With the exception of low temperature hot water heating boilers, boiler blowdown is discharged to a flash tank where some of the energy in the high temperature water is used to convert some of the water to steam that is vented to atmosphere. The remaining water, now at 212°F, is conveyed to a drain. The Plumbing Code clearly restricts the temperature entering a drain to 140°F. Therefore, high quality drinking water is used to cool the hot water by dumping more water down the drain. This is referred to as quench water and it is normally high quality drinking water that goes down the drain to sewer along with the blowdown. The typical blowdown heat recovery system cools the blowdown to about 90°F, in which case quenching with fresh water is not required. When the cost of the additional water is considered, the economics of the heat recovery system usually work out. Further, as time goes on, there will be more emphasis on overall efficiency as a means to reduce greenhouse gas emissions. Finally, potable water is becoming a prized resource that is not to be wasted. There is a Sustainability Accounting Standards Board (SASB) that prepares sustainability evaluations for companies. Wasting a prime resource such as potable water is not a good way to improve a sustainability score.
Basic Steam Plant Calculations
Published in V. Canapathx, Steam Plant Calculations Manual, 2017
Steam plant engineers have to frequently perform energy and mass balance calculations around the deaerator and boiler to obtain the values of makeup water, blowdown, or deaeration steam flows. Boiler blowdown quantity depends on the TDS (total dissolved solids) of boiler water and the incoming makeup water. Figure 1.2 shows the scheme around a simple deaerator. Note that there could be several condensate returns. This analysis does not consider venting of steam from the deaerator or the heating of makeup using the blowdown water. These refinements can be done later to fine tune the results.
Boiler and Steam Systems
Published in Scott Dunning, Larry S. Katz, Energy Calculations & Problem Solving Sourcebook, 2020
Boiler blowdown is the process of removing water from the boiler that contains impurities as a result of steam evaporation. Steam pressure is utilized to blow water out of the boiler, and make-up water is then added.
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
The aim of this paper is to show the energy saving potential in the steam industry in Greece. The paper presents the results of energy audits that were carried out in 10 industries that use steam. During the audits, information was collected on the energy profile of the industries and their steam processes (generation, distribution and end use). Additionally, measurements were carried out at the different parts of the steam boilers and distribution lines. The measurements included flow rates, daily volumetric measurements, return condensates, make-up water flow rates, boiler efficiency, thermography of the mechanical equipment, and inspection of steam traps in order to identify areas of energy leakages. Based on the audit results, a series of energy efficiency measures were proposed for each industry. The proposed measures for the 10 audited industries result in a total of energy savings of 5.8 GWh/year indicating the potential of energy conservation in the Greek Steam Industry and in the Greek Industry as a total. The main conclusions concerning the energy efficiency measures are listed below, starting with the ones with the lower payback period: insulation of uninsulated areas of the boilers, i.e. the insulation of approx. 20 m2 of boilers may contribute in energy savings around 50–100 MWh/year, with a payback period maximum to 1 year.insulation of the distribution system results in energy savings that according to the length of the pipes may range from 40 to 330 MWh/year, with an average payback period of 2 years.installation of an automatic blow down control system ranges from 40 to 220 MWh/year with a payback period from 1 year to 3 years.implementation of economisers (to preheat the make-up water) for waste heat recovery which results in energy savings from 130 to 400 MWh/year with a payback period around 4–6 years.implementation of waste heat recovery for the boiler blowdown and/or steam condensate. This measure results in approximate energy savings of 100 MWh/year with the payback period from 5 to 10 years.