Antero Punttila Analyzing most typical energy saving measures Energy Efficiency of Steam and Condensate Systems Antero Punttila, Motiva Oy.

Antero Punttila Steam systems in industry and other sectors Steam can be used for heating, drying, moistening and sterilization of products in industry and other fields Steam has advantages in effective heat transfer, indirect or direct heating and hygienic. Special attention shall be given in productivity of steam production (exhaust gas and blowout losses), distribution networks and steam users. Water treatment and high maintenance needs may increase operating costs.

Antero Punttila Steam production Steam can be produced by steam boilers and steam generators. Key factors in economic steam production boiler plant continuous consumption monitoring skilled personnel Considerations in boilers boiler capacity meets steam requirements meters are in good condition out-blow is not excessive economizer is in operation heat transfer surfaces are clean boiler has no air leakages boiler insulation is in good condition

Antero Punttila Steam networks Steam use can be either direct or indirect, but the used energy amount is the same, but heat losses may differ. In direct use the valuable condensing water return shall be checked regularly Superheated steam has lower heat transfer coefficient than saturated steam Moist steam stress equipment more than dry steam Air mixed in steam reduces the heat transfer coefficient

Antero Punttila Leaks Leaks in steam systems waste continuously energy (24/7) reduce network pressure and energy flow waste valuable condense water (treated water) reduce work safety (blasts) To be checked visually or with ultrasonic detector safety valves, steam traps, orifice connectors, gate valves, unattended pipe-tunnels leakage inspections shall be made at least twice per year

Antero Punttila Pipe and equipment insulation Pipes, flanges, equipment and valves shall be insulated because of heat losses and working safety Condense pipes always insulated, except condense valves Wet insulation causes energy waste and outside corrosion Un-insulated DN 200 valve may have up to 200 C temperature and 5 kW continuous heat loss

Antero Punttila Condense return Condense return is important in indirect steam use. Condense traps are important. Precise condense return causes: good utilization of condense heat content reduction in make-up water needs Closure of open condense tank causes reduction in heat loss reduction in tank corrosion Condense tank should be blanketed from oxygen entry by steam etc

Antero Punttila Failures in condense traps Condense return rate shall be monitored and maximized Fault trap causes steam-condense mix in condense pipe leading to increased temperate and backpressure, increased steam consumption, higher condense and high feed water pumping costs Faults in condense traps should be seek by listening (man / machine) and by temperature metering (every 2 to 4 months)

Antero Punttila Utilization of blowout steam (expansion steam) Benefits of blowout Reduced steam consumption Lost blowout steam reduces Capacity of condensing network increases Utilization of blowout steam Blowout steam usage in low pressure systems Preheating of combustion air, compressed air and rooms Heating of sub-cooled condense or preheating of process- water in condense tank

Antero Punttila Economical use of steam Steam pressure Is defined by required temperature /pressure level It is important that temperature/pressure meets the user requirements It is important that pressure fluctuation is as small as possible Steam networks can be divided by pressure reduction valves to different pressure subnets

Antero Punttila Equipment considerations Very important that process automation works properly Steam network and equipment shall be started slowly Steam heated equipment shall have thermal insulation Open liquid surfaces shall be covered against evaporation Bypass valves shall be kept closed and watertight Minimization of steam pressure, finally replacing steam with hot water Drying first by mechanical water removal, then steam- drying and avoid over-drying Avoid unnecessary stand by use of steam systems

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