Smart melting
The term intelligent melting ( English : smart melting ) includes the communicative networking and control of an energetically optimized melting plant in the metal industry. The term Smart Melting was coined by the Competence Center for Industrial Energy Efficiency (KIEff) at Ansbach University and used for the first time in 2012 as part of a sub-project in the Green Factory Bavaria research association. Smart Melting enables the melting operation to be integrated into an intelligent power grid (smart grid). The aim is to contribute to network stability and security of supply and to use the economic advantages that arise from an intelligent power grid.
Background and motivation
In the course of the energy transition, the power grid is subject to strong fluctuations in terms of feed-in and load, which increases grid overload and the risk of collapse. Since industry is the largest consumer of electricity, it is necessary to integrate the energy-intensive industrial processes into an intelligent power grid in order to avoid peak loads. The metal smelting processes are among the most energy-intensive processes.
Establishment of an intelligent melting shop
In an intelligent melting operation, the parameters of production capacity , melting demand , electricity supply and storage capacity are linked by a process management system and production is designed to stabilize the network. In order to better adapt production to network fluctuations, an additional liquid metal storage facility is installed, which enables lower production when there is a high network load and greater production when there is less network load. In addition, it enables longer driving at the optimal operating point and thus leads to an energetically optimized system operation. By using thermal storage systems, the downstream processes (e.g. ingot preheating, hall heating) can be supplied with the required thermal energy even when production is low. In addition to electricity, smelting operations are primarily operated with gas. Special strategies have to be developed for the integration of gas-powered processes into an intelligent power grid.
advantages
Economic advantages through smart melting
In an intelligent power grid, the price of electricity is based on supply and demand. The intelligent smelter takes up this idea and tries, with the help of predictive process management, to use the times for the smelting process when the demand for electricity is low, the supply is high and the electricity price is low. Another economic advantage arises from the fact that the liquid metal and heat accumulators mean that the system can be operated for longer at the optimal operating point, thus increasing the melting efficiency and reducing energy costs.
Smart melting as energy storage
An intelligent melting operation can help relieve the load on the power grid and at the same time serve as an energy store. When electricity demand is low, energy is taken from the power grid for the melting process. This energy is stored in the form of thermal energy in the melting furnace or in the liquid metal store and in other heat stores. If there are load peaks in the network, the stored liquid aluminum is processed further, thus reducing the electricity requirement at peak load times. The energy storage of the intelligent melting operation is emptied again. Due to the large quantities that are processed in the metal industry and the high heat capacity of metals, there is a very large storage potential here.
Stabilization of the network through smart melting
A positive effect of using the energy stored in the liquid metal storage system at peak load times is the decrease in electricity demand at these times and thus the relief of the power grid. Smart Melting therefore has a double stabilizing effect on the power grid. If the mains frequency is too high, it takes H. if there is too much electricity, take energy from the grid and store it. During the main production times, i.e. when there is great demand, the previously extracted energy, which was stored in the form of thermal energy, is used and the load on the power grid is thus relieved.
Renewable Energies and Smart Melting
Wind and sun are among the energy sources of renewable energies with the greatest fluctuations and are at the same time the largest suppliers of renewable energy in the form of electricity. This means that the power grid is more heavily loaded. Stormy nights or sunny holidays put a particular strain on the network, as industry, as the largest energy consumer, only needs a fraction of the normal energy requirement at these times. As a result, wind power plants and larger solar parks have to be switched off temporarily or conventional power plants such as coal or gas power plants have to be turned down, which leads to a deterioration in efficiency. In an intelligent smelting plant , some of the excess electricity generated by renewable energies can be taken from the grid. This means that wind power plants or solar parks do not have to be switched off and therefore no renewable energies are lost.
Challenges
Smart Melting is based on the basic idea that metal is melted using electrical energy. However, many smelters work with conventional energy sources such as coal or gas, as these are currently cheaper than using electricity. The use of electrical energy to melt the metals can only be economical in an intelligent power grid where the electricity prices are temporarily cheaper. To enable a melting shop to be integrated into an intelligent power grid, the process flow in the melting shop itself must first be intelligent. The exhaustion of the control and regulation potential plays an important role here. In many smelters there is a lack of communication between the individual production steps or they do not have the necessary process monitoring. Another challenge is that it must be possible to store the liquid metal. Melting plants have to move from the current just-in-time production of the melt to production in stock, with the option of producing not only melt for the next two to three hours, but for the next two to three shifts. To make this possible, systems with higher melting capacities and larger storage facilities for the liquid melt are required.
disadvantage
For the implementation of Smart Melting , higher investment costs are to be expected compared to the previous operating method. This is due to the greater melting capacity and the storage capacity for the liquid melt. In addition, the storage of liquid melt increases the energy requirement for storage.
Web links
- KIEff Competence Center for Industrial Energy Efficiency at Ansbach University
- Press release Bavarian Parliament approves multi-million dollar funding for Green Factory Bavaria (PDF; 50 kB)
Individual evidence
- ↑ Source: BDEW, status 08/2012