Processes 2021 , 9 , 1707
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This action controlling the wear state of the rotary joint has been performed since the responsibility of controlling the fresh water ( Cw ) boiler transferred to maintenance personnel. The maintenance personnel now understand the entire circuit of steam and con- densate and are aware of the amount of steam lost by rotating joints in poor condition and the benefits of controlling its maintenance state. This control is fundamental for reducing the scheduled maintenance of the drying section recommended by the manufacturer and preventing steam losses. 2.2.2. Temperature of the Air Blown into the Dryer Section Hood The drying section enclosure hood has two exhausts—hot air from inside the hood and a fan that blows hot air at the same flow rate to compensate for the extracted air. This air stream is passed through a series of three heat exchangers that harness the heat energy contained in the exhaust air stream, generate flash steam in the last condensate collection tank, and collect water condensate, which is returned to the boiler. To determine the airflow, all the technical fan characteristics, including the consumption curve airflow (m 3 ) through which the flow of air is introduced into the hood, must be known. The motor power consumption is determined by the operating parameters of the fan. 2.3. Data Collection The calculation of the subinstallation output production (Pp) to set the indicator in reference periods is based on the following guidelines indicated in methodological guidelines for ECOFYS for the European Commission [54–56]. The study is based on a representative period of production in which there are neither changes in machine conditions nor alterations that change the production capacity. The following parameters are collected to determine the amount of paper produced and energy consumption: • Pp: Paper production (t). • Ms: Machine speed (m/min). • Pd: Manufactured paper density (g/m 2 ) (area density, according to ISO 536 [52]. • Pwi: Paper width entering the drying section (mm). • Paper conditions before and after the drying section: • Twt: Water temperature at the entrance to the drying section ( ◦ C). • Pti: Paper temperature entering the drying section ( ◦ C). • Pmi: Moisture content of the paper entering the drying section (%). • Pto: Paper temperature leaving the drying section ( ◦ C). • Pmo: Moisture of the paper leaving the drying section (%). • Drying section conditions: • Sf: Drying section feed steam flow rate (kg). • St: Drying section feed steam temperature ( ◦ C). • Sp: Drying section feed steam pressure (bar). • Ct: Temperature of the condensates extracted from the drying section ( ◦ C) • Cp: Pressure of the condensates extracted from the drying section (bar). • Eat: Temperature of the exhaust air ( ◦ C). • Eam: Moisture content of the exhaust air (% saturation). • Ebt: Temperature of the blown air ( ◦ C). • Ebm: Moisture content of the blown air (% saturation). • Ot: Outside temperature ( ◦ C) The parameters indicated above are used in this work as follows: Ms, Pwi, and Pd are used to calculate the subfacility output Pp in a period and later to calculate the indicator under study. Sf, St, Sp, Ct, and Cp are used to calculate the activity data (Equation (3)). To perform this analysis, we use the machine’s control instrumentation based on Beckhoff hardware with the SCADA Wonderware display system ‘Smart Control’ Quality Control System (QCS) and Process Control System.
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