As the area grew and people moved into their houses, “The Vac”, as the system is called here, expanded and was upgraded several times. Today, it is one of the most outstanding installations of Envac, applying the latest technology and with a control system ready to meet the challenges of tomorrow’s waste disposal plans.

The owner of the three fraction system in Eriksberg is Eriksberg Cooperative, which awarded Envac the operations and maintenance contract. The first upgrade took place eleven years after the system commissioning, as the fans were replaced and frequency converters were installed, measures which together resulted in a energy consumption reduction by 30 percent.

The collection station expanded in 2008 with an additional cyclone, a compactor and a residual waste fraction container to handle the increasing amounts of waste originating from the completion of new buildings in the suburb. To adjust the capacity and improve operations, a number of initiatives were taken which could better meet the needs and requirements involved with a modern automated waste disposal system.

Level sensors

The system in Eriksberg has many waste inlets installed with relatively shallow intermediate storage chutes due to ground conditions and its proximity to the sea. Because of the extended period of construction and the large number of inlets with low storage volumes, the system is well suited for optimised emptying through the use of level sensors. As a result inlet level sensors were installed in 2008 that also brought about improved emptying routines and a reduction in the risk of overfilled inlets.

Level sensors have many advantages, the greatest of which are the energy savings in operating the system. Level sensors enable needs-based waste disposal, a reduction in the number of system starts and shorter fan exhauster operations times, since only full inlets need to be emptied. Thanks to the introduction of level sensors and improved emptying routines, energy consumption has been reduced by 40 percent. Areas with the vacuum system that use inlets unevenly, for example due to the on-going construction expansion work or a mixture of commercial and household waste, benefit from the installation of level sensors that control the emptying of the inlets.

Commercial premises often have large quantities of waste that must be deposited in the inlet in a short time, while this is not usually the case with household waste. Consequently, controlled needs-based emptying is beneficial in terms of energy use in a mixed usage area like this. Additionally the level sensors prevent the inlets’ becoming overfilled which is a clear benefit.

Hardware and software

“The Vac” in Eriksberg is being upgraded in the autumn of 2010 with a new system developed by Envac, the EAP (Envac Automation Platform). This is the brain of the system and it is our ultimate way of ensuring optimal operations. Since the platform is module-based and thus easy to expand, the usage of EAP ensures that the hardware running the vacuum waste system is ready for future expansion.

More and more features are being built into our software to bring about a balanced operations mode especially in terms of automation, energy consumption and service levels. For example, enabling the VDOT (Valve Dynamic Open Time) function in our software produces an energy saving of up to 15 percent in a system with analogue level sensors. Intelligent collection is already a reality and for the Eriksberg vacuum system, the environmental benefits and the energy savings have progressively been achieved. Envac is also developing new intelligent concepts which are based on applications adapted to the waste system flow thus minimising energy consumption.

The future

The Eriksberg installation is not yet fully completed. The system installed has the capacity to handle large amounts of waste and new buildings are still added and connected. Envac is now looking more closely at combined solutions for Eriksberg which include heat exchangers, heat recovery and secondary energy sources.

Through its proximity to energy consumers and households, a waste station is suitable for the installation of secondary energy sources such as geothermal or solar cells. For example, it is possible to use the thermal energy from the vacuum system produced in its self by adding it into the district heating network or through conversion to cooling in the district cooling network.

Our projections for Eriksberg in terms of heat recovery of excess heat from the exhausters show possible reductions of up to 20 percent of the total vacuum system energy consumption.