Regulation and monitoring system optimizes the operation of ventilation technology
The traditional company Kartonfabrik Buchmann GmbH produces high-quality folding boxboard. Board machine 3 has been running there for 55 years, and the ventilation technology in the hoods was last adjusted 20 years ago. The production output from the machine has been constantly increased over the years. Time, therefore, to gear the machine ventilation technology towards the future as well: A project to replace the machine ventilation technology should improve energy efficiency, productivity and transparency. Thanks to a regulation and monitoring system, as well as the maintenance-friendly design, the system is always operated at the optimum operating point, component maintenance is made easier, and performance and energy efficiency are guaranteed for a long period of time. Bayreuth-based airinotec was entrusted with the planning and implementation.
Sustainable board production in a biosphere reserve
Buchmann Karton’s production facility is located in the middle of the Pfälzerwald-Nordvogesen biosphere reserve. Around 350 employees produce roughly 250,000 tons of folding boxboard there in a year. Board machine 3 has been running since 1966. Since then, it has been upgraded and expanded multiple times, as a result of which the ventilation technology no longer measured up to the requirements of the machine. That’s why the management decided to arrange for modernization: The course should be set towards a sustainable future with improvement of the energy recovery ratios and reduction of the energy consumption for the ventilation technology, as well as optimized operation and improved monitoring and diagnostic tools for the ventilation technology.
Requirements for the new machine ventilation technology
Sustainability – it affects the definition of multiple goals in this context. A primary requirement asked of airinotec was to improve the energy efficiency of the system. The previously unused waste heat from the after-dryer section should be fed into the heating water circuit at various temperature levels to this end, and more energy should be saved through the new control systems. A monitoring should provide support for diagnostics and maintenance on the one hand and at the same time bring transparency to the ventilation technology on the other: The operating states of the ventilation technology should be visible at all times, just like the energy consumption. The final requirements related to the implementation: The renovation should have the least possible impact on production – so a short period of system downtime would have to suffice. The planning would also have to cope with the tight space.
Technical concept to achieve the goals
In order to achieve the desired goals, a ventilation concept for the drying hood which was precisely tailored to the conditions on-site was developed in close collaboration with the client. When it came to the technical components, the airinotec engineers opted for the following solution: First, a machine exhaust fan (radial fan) should be installed. Two stainless steel air-water heat recovery systems with an output of 1300 and 3100 kW, a droplet separator with stainless steel ribs and an exhaust silencer with extendable wings for cleaning should be used in the exhaust air lines for the after-dryer section. For the supply air, the planning provided for an intake with filter, multiple heaters to heat the machine supply air using waste heat from the machine exhaust air and vapor heaters, as well as a steam heater. A radial fan would also be used for the machine supply air. Alongside the supply air and exhaust air, the air ducting from the fan to the drying hood was also redesigned. In addition, the air distribution inside the extractor hood is also adjusted. The supply air is blown out evenly close to the paper web across the entirety of the after-dryer section. The ventilation of the machine is thus improved, which in turn improves the drying capacity in the after-dryer section. Maintenance-friendly access point were established for all components in the exhaust air and supply air here.
The first goal: Improving energy efficiency
Various measures were included in the planning in order to achieve the energy efficiency goals. The first relates to the use of waste heat: The primary energy requirements will be reduced in the future through the use of waste heat which has not been recovered until now. To this end, waste heat from the machine exhaust air in the after-dryer section is used both to preheat the required machine supply air and to transfer the excess waste heat into the hot water system for the hall ventilation in the KM3 hall and other hall areas. This measure is able to achieve a reduction in steam consumption and therefore a reduction in primary energy consumption, thus making the project eligible for funding from the Kreditanstalt für Wiederaufbau (Credit Institute for Reconstruction, KfW). Energy consumption at the auxiliary condenser, which condenses the flash steam into condensate, is reduced through the use of flash steam to heat the machine supply air. Previously, the energy contained in vapor was discharged into the environment partially unused, with additional energy expenditure in the auxiliary condenser.
“Optimized operation and monitoring of the ventilation technology makes a major contribution to improving the efficiency of ventilation technology systems. Monitoring in turn leads to transparency, extends the service life of the components through proactive maintenance and facilitates a good overview of the operation of the system – even with fewer staff.” (Simon Linhardt, Sales Engineer at airinotec GmbH)
The second goal: Transparency through monitoring
Alongside energy efficiency, Buchmann’s list included another key goal: monitoring of the ventilation technology installed. An extensive monitoring system which monitors the ventilation technology at the important and critical points helps to create transparency regarding the operating status of the components. At the same time, it provides support for fault diagnosis, maintenance and servicing. The degree of soiling on individual components is monitored depending on the variable air volumes and communicated to the Siemens PCS7 process control system. Intelligent dedusting modules ensure that components are automatically cleaned so as to ensure that they function properly – while keeping water or compressed air consumption as low as possible. The monitoring system is purposeful with regard to energy efficiency too: Incorrect fan operating points, perhaps owing to soiling, damage to components or incorrect settings, interfere with ventilation of the machine and result in the energy consumption being too high. In order to prevent this, various fan parameters such as air volume flow, pressures, power consumption and rotational speed are constantly monitored online. Errors are quickly discovered as a result and can be corrected.
In addition to project planning for the monitoring system, care was taken in the planning phase to ensure that readily accessible maintenance accesses were established. Positions for trades with regular maintenance points were jointly defined with the client with the aim of providing the best possible support for maintenance.
The triple of monitoring, regular maintenance and transparency through the data collected provides a range of benefits: It makes forward planning of maintenance work possible, thus ensuring the system is taken care of. Thanks to early detection of malfunctions, rapid correction is possible and outages are therefore minimized. Since all of the data collected is displayed and processed in the process control system, all systems remain in sight even with lower staffing levels – no more “flying blind”.
The third goal: Optimal operation in rapidly changing production with EnergyOpt
The EnergyOpt control software, which was created in order to save energy through regulation of the fans and heaters, is part of the scope of delivery from airinotec. This requires the optimal operating point for the ventilation technology to be found. Various factors must be taken into consideration for this: The production output in paper manufacturing, heat recovery rates, energy efficiency, the structural conditions (such as tightness of the drying hood) and of course the specifications which the operator must comply with in relation to accessibility of the system. The appropriate parameters are collected through measuring points and analyzed by EnergyOpt. EnergyOpt is integrated into the Siemens PCS7 process control system.
Correct and reliable measured values form the basis for an innovative regulation strategy. airinotec can look back on many years of experience here: Both selected sensors and plausibility and failure checks and specific redundancy at the measuring points ensure a reliable regulation strategy. Every paper or board machine is unique. That’s why EnergyOpt is tailored to each machine. In addition, the system is designed such that the client can always adjust EnergyOpt to account for changes to the board machine and its specific needs and can continually optimize it. airinotec supports the client in this optimization and learning phase. The setting parameters are set here such that energy efficiency, the positive impact on production and proactive maintenance are improved through the empirical values obtained. Remote access for quick and competent online support is an ideal help.
Renovation during a short period of system downtime
In addition to the goals which should be achieved with the ventilation technology project, companies require that production downtimes owing to system downtime are kept as low as possible and the available floor space is used as efficiently as possible for retrofit projects. These requirements can only be met with perfect preliminary planning and coordination of installation and return to service. Cooperation between the individual trades, which generally include construction, steel construction, ventilation technology, wiring, programming, pipework and insulation, must be reconciled and coordinated down to the last detail so that there are no clashes and delays. In the case of the Buchmann project, this was an exemplary success: Renovation of the ventilation technology in the after-dryer system was possible with just five days of downtime.