Industrial boilers Planner Guide (steam systems 1) 2014 by Hoval USA

More catalogs by Hoval USA | Industrial boilers Planner Guide (steam systems 1) 2014 | 88 pages | 2017-03-17


Page 27 of Industrial boilers Planner Guide (steam systems 1) 2014

small to medium size steam boilers condensate return as steam is generated the water within the boiler evaporates and is replaced by pumping feed water into the boiler down make-up chemically treated water will therefore have to be introduced to the system to maintain the correct working levels as the steam passes around the system to the various items of steam-using plant it changes state back to condensate which is essentially very good quality hot water the return of condensate represents huge potential for energy savings in the boiler house condensate has a high heat content and approximately 1 less fuel is required for every 6°c temperature rise in the feed tank unless some contamination is likely perhaps due to the process this condensate is ideal boiler feed water it makes economic sense therefore to return as much as possible for re-use in reality it is almost impossible to return all the condensate some steam may have been injected directly into the process for applications such as humidification and steam injection and there will usually be water losses from the boiler itself for instance via blow 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 figure 3.11.5a shows the formation of steam at 10 bar g when the boiler is supplied with cold feed water at 10°c the portion at the bottom of the diagram represents the enthalpy 42 kj kg available in the feed water a further 740 kj kg of heat energy has to be added to the water in the boiler before saturation temperature at 10 bar g is reached fig 3.11.5 comparison of energy to raise steam at 10 barg formation of 1 kg of steam 10 bar g – feedwater 10°c formation of 1 kg of steam 10 bar g – feedwater 70°c requires 9.2 less energy 27