Process Heating Process Heating Corrugator Condensate Refeeding

Heating Systems Heating Systems Introducing to Calculation Introducing to Calculation of Heat Recovery of Heat Recovery Calculation of Heat Recovery Calculation of Heat Recovery Scheme Description Scheme Description World Map World Map End Content

Open and Closed Steam System

Introducing to Calculation of Heat Recovery Our following calculation of heat recovery is based on a corrugator plant with 2 single facers, 1 triple heater and 1 double facer with 20 heat plates. This configuration has a steam consumption of about kg/h.Two basicially different steam- and condensate systems namely an open and a closed are compared in this calculation. The open system is the traditional system. It has two big advantages : ●its low purchase costs and ●its high differential pressure between steam- and condensate side, which is ideal for a good draining of the machines. The condensate is coming out of the machines and is collected into a pressureless tank which is open to the atmosphere (see schematic please). The total high pressure condensate of the plant evaporates into the atmosphere.The result are extreme losses of energy and soft water. This big disadvantage of the open system is no alternative to an closed system in view of increasing energy costs in the future. The following economic efficiency calculation will approve this. Please take some time it’s worth it. Enclose some explanations to the calculation : A kg/h high pressure condensate evaporates from 10 barg (184 °C ) to 0 barg (atmospheric pressure) into pressureless tank. According the re-evaporation diagram (see background) you lost 16 % evaporation steam it means 720 kg/h. B Kg/h fresh water (500 kg/h steam shower losses kg/h evaporation losses) must be heaten up from 10° C until 103 °C (deaeroation temperature in the feed water tank). The steam boiler must produce 244 kg/h steam in order to heaten up 1220 kg/h fresh water in the open system. C. In the closed system however the boiler must heaten up only 100 Kg/h Fresh water for steam shower losses. D. As the condensate is feed back directly to the boiler with an higher condensate temperature (176° C) compared with the open system (103°C ) a reduced heat quantity is necessary. E. The investment costs include a high pressure condensate unit with tank and pump, closed feed water tank, switch cabinet and installation costs. As you can see within less more than 1 year the investment will be amortized.Please consider the calculation was made for a two shift operation. The payback period for a three shift operation will be shorter. If you make your own calculation you should take your local costs for energy and water in column F.

Calculation of Heat Recovery Basis data: Steam boilerload:5.000kg/hCondensate back to boiler 90%:4.500kg/h at 10barg and 184°C Working Pressure:14bargFresh water feeding 10%: 500kg/h (replacement for steam Running hours:16 h/d at 220 d/Y shower, leaks etc.) 4500 kg/h evaporates from 10barg to 0bar(Atmosphere) ≙ 16% re-ev ≙ 720 kg/h Fresh Water HEATING: ( ) kg/h FW (10°C → 103°C) HEATING: 500 kg/h (10°C → 103°C) Blending (condensate) 4500 kg/h of 184°C with (feed water ) 500 kg/h of 103°C OPEN SYSTEMCLOSED SYSTEM D Investment Gain by steam saving Gain by fresh water saving Gain by fuel saving Complete Gain re-evaporation% A B C F E Mass of steam per hour Blending temperature Energy difference per hour Specific heat capacity 4,18 KJ/Kg K Net calorific value KJ/Kg Density of light oil 0,82 Kg/L Boiler efficiency 90 % Mass of oil saving per hour

Scheme

Scheme Description Some explanations to the function of our system (see schematic please) G.Independed pressure (temperature) control unit for a single facer For a low grammage paper production it is necessary to adapt the temperatures of a single machine (for example e-flute). Low grammage paper or preprint require low temperatures in order to prevent overheating of the paper. For that reason we have developed these control unit G. You can control down until 7 barg and you can exactly adjust the temprature for your used paper quality. H.Independed pressure (temperature) control unit for double facer. With the double facer control units H all sections can be controlled down indendently until 1 barg (120 ° C). Conventional power traps have about the 5 – 6 fold on operating cycles by reasons of its small storage space. K.The high pressure condensate pump is frequency controlled and for that reason only a small high pressure condensate tank is necessary. L.Prepressure control in order to protect the condensate pump from cavitation. I.Start-up automatic in order to defend the boiler from heat tensions and overfilling in the start-up period.

Worldwide Installations For please contact CALIQUA-BORMANN office List of Reference

Thank you for your attention Thank you for your attention For further information please contact our office CALIQUA-BORMANN GmbH & Co. KG Wärme- und Klimatechnik Frankfurter Ring München Germany