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Inlet air passes through three heat exchangers, each of which has a separate power source that provides energy to the blown airflow. The first-level-of-action personnel, who are responsible for cleaning the equipment, are assigned the task of tracking the parameters once a day. This approach is taken to involve the manufacturing staff in the prevention of the decrease in Ebt, which results in increased consumption of steam, and to review the cleanliness of the exchangers listed above. The maintenance actions resulting from the measurements of the temperature values are performed on July 8 on the following equipment: The air–air exchanger harnesses the energy extracted from the airflow in the hood to warm blown air. This exchanger heats the air up to 45 ◦ C above the external temperature. The water–air exchanger, which harnesses the energy of the condensate, returns to the boiler to heat the blown air to 75 ◦ C. The flash steam exchanger harnesses flash steam generated in the last low-pressure condensate collection tank and heats the blown air to 95 ◦ C. The temperature reached at the end of the exchanger system for blown air is 97 ◦ C, but only 32,892 m 3 /h is obtained. The difference between the air flow compensation comes from the inside of the manufacturing hall where the enclosure hood is located. TheCO 2 emissions associated with energy losses are calculated through the energy supplied to the flow of hot air blowing from the actual temperature to the desired tempera- ture. This energy comes exclusively from the boiler to generate steam supplied to the dryer section. This boiler steam generation exclusively uses natural gas as an energy source. The emissions can then be calculated using Equation (2), which considers the energy provided to the air and the emissions factors associated with the consumption of natural gas needed to heat that air. Subsequently, the ‘energy losses/emissions’ are calculated according to Equation (3) and compared with the difference in the temperature of the blown air Ebt into the hood with an indicator defined by Calvo and Domingo [21,62], ‘t CO 2 /t Paper’, to determine the relevance of the losses. The average ADT of paper produced in the factory is 5.75 t/h, and the only source of energy used in drying the paper comes from the steam generated in a single boiler. Natural gas is supplied to the plant by a single source, and the only gas consumption occurs in the boiler steam generation. The average energy consumption for each paper ton is 1190 kWh. With these data, as shown in Table 2, the portion of energy lost in the blown air corresponds to 10.17% of the total energy used in the thermal drying of the paper. The support guidelines for the exchangers are established in months M7-M12 of year 8.
Table2. Emissions balance.
Energy (kWh)
CO 2 Emissions (t)
Hour 695.94 6842.50
Hour
Total Year
%
Difference in blowing air Total energy consumption
0.125821 1.237069
1011.60 9946.04
10.17
3.3. Evolution of the CO 2 Emissions The first action (Cw) is performed continuously, and the second (Ebt) is performed after 6 months. Table 3 shows the quantification of savings blow-down energy, savings exchangers energy, and total energy savings over 10 years. The losses or reductions always refer to days of operation, a very important parameter in this type of plant, in which the start-up and shutdown processes are periods of intensive heating energy consumption and energy released not directly applied to production. These types of situations are beyond the scope of this paper. On the other hand, the impact of the measurement of the exchangers is much more significant than that of the purges, due to the amount of air conveyed in the drying installation that is expelled to the atmosphere in a more continuous manner.
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