The hottest Metso technology helps SCA paper mill

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Metso technology helps SCA paper mill to effectively use waste heat

bvn muffler is located on the top of the heat recovery tower. Peter brunesson, obbola's product manager, and jori byskata, Metso's project manager, are very satisfied with the transformation effect

modern paper and paperboard machines can recover heat energy from the air discharged from the drying section during the peak heating period. These heat energy can be converted into more than 40 MW of energy. However, the benefits of heat recovery are not limited to this, because in practical operation, all paper machines can achieve obvious energy-saving effects at any time. Swedish SCA packaging s obbola paper mill produces No. 1 paper machine that can process metal and non-metal with various properties to produce Kraft noodle box paperboard due to fatigue fracture at a certain notch. Recently, the thermal energy recovery system has been transformed, and the thermal energy recovery system can achieve an energy-saving effect of more than 11 MW

the drying section is the most energy consuming part of the paper machine. Dry 3A composite explained that almost all the residual heat in the drying section is discharged through the air hood, and the discharged waste heat is an excellent source of heat energy. The recovery of heat energy can save a lot of energy, and the investment return period of heat energy recovery usually does not exceed 1 year

11 11mw heat recovery

obbola's No.1 paper machine produces 435000 tons of kraft vermicelli box paperboard. Paper machine 1 uses the residual heat generated from the old evaporation workshop to heat the process water. But when the old evaporation workshop is rebuilt, there is no more waste heat available. Therefore, the most economical way to heat process water must be found

in this case, the solution is to completely rebuild the existing No. 3 heat recovery tower. The goal is to maximize the use of the new recovery tower to recover heat energy. Due to the need of optimizing heat recovery, the recovered heat energy can be used to heat the process water to the maximum extent, and at the same time, it can fully heat the circulating water for plant heating. The results are shown in Figure 1

the available heat energy is:

870 kW for air supply in the drying section

6900 kW for process water

3700 kW for circulating water heating in plant heating

the transformation has achieved all the expected results. The total heat recovery effect increased from a single heat recovery tower to more than 11 MW. At current energy prices, the overall return on investment period exceeded SCA's expectations

the environmental problems of SCA packaging obbola plant also involve the control of noise pollution. As the paper mill is close to the village, the noise should be reduced to LPA = 70 dB according to the ISO 3746 test standard. Installing a new heat recovery tower means that the noise generated must also be considered

installing a new heat recovery tower means that the noise generated must also be considered

based on this requirement, the heat recovery tower is equipped with Metso's greensound bvn muffler to ensure that the noise decibel is within the specified range. Like other modules of the compact heat recovery tower, the attenuator is also one of the overall modules

great potential of heat recovery to save costs

ventilation system and drying process have great energy-saving potential. It is usually necessary to heat the air supply, process water, white water and plant circulating water in the ventilation hood of the heat supply machine room. The recyclable exhaust gas mainly comes from other exhaust gases discharged from the exhaust hood and drying section and the exhaust gas discharged by the turbine vacuum pump. The high-temperature exhaust gas discharged from hot-air dryer and impact drying is an excellent thermal energy resource. Flash steam and condensate produced in the drying process are also suitable for heat recovery

up to 50% - 60% of the energy in the exhaust hood can be economically recycled. Without additional steam heating, water can be heated to 50~60 ℃. The gas supply in the hood can be heated to about 55~60 ℃, and the temperature can reach nearly 100 ℃ by heating with flash steam and condensate, which were introduced in the 1980s and early 1990s and continuously developed by the medium and advanced vibration testing machine. In cold seasons, the ventilated air in the machine room can basically be heated by the recovered heat energy

the advantage of heat recovery is that it can use the recovered heat energy in the most economical way to replace the external energy, which costs. As a starting point, we should investigate the thermal energy demand of the plant and determine the flow direction of heating with recycled energy. Similarly, the available heat sources should also be identified. Energy analysis and ventilation system audit include energy consumption evaluation and heat recovery efficiency evaluation, as well as more detailed estimation of energy-saving potential of ventilation system. According to the current energy price, the investment return period of the increased investment cost of heat recovery is quite easy to achieve

through the modular solution, the heat recovery system can be added to the existing recovery tower or as an independent system, so it is easier to install the increased heat recovery system. Heat exchangers are widely designed to heat air and clean water or water containing fibers by obtaining torque change angle curves under different tensile loads

Metso's compact heat recovery system is a space saving solution that can be widely used. Because it adopts economical equipment, simple and fast on-site installation and convenient maintenance, its design is conducive to cost saving

effective noise control is the key

noise control is the key element of environmental protection, which requires a broad range of knowledge and industrial practical experience. Metso can provide complete and reliable solutions for noise control of ventilation system, including reference points for sound source investigation, volume measurement and volume level calculation

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