Procedure for operating an asphalt mixing plant

Abstract

The invention relates to a method for operating an asphalt mixing plant (AMA), wherein energy is supplied, characterized by the following steps: - Biomass (BM) is fed into a pyrolysis plant (PYR); - the waste heat generated in the pyrolysis plant (PYR) is fed into a heat storage unit (WS); - the heat storage (WS) supplies the asphalt mixing plant (AMA) with energy.

Description

Technical area

[0001] The invention relates to a method for operating an asphalt mixing plant according to the preamble of claim 1. State of the art

[0002] Such procedures are already known and in use in a variety of forms and designs.

[0003] Asphalt production is a complex process that takes place in a highly automated asphalt mixing plant. In an asphalt mixing plant, various aggregates are selected, dosed, and mixed according to the requirements of the final product.

[0004] The process requires temperatures of > 100 °C to eliminate the natural moisture from the rock. Therefore, the asphalt mixing plant incorporates a thermal drying process that requires high heat output.

[0005] The binder bitumen is added and thoroughly mixed in the asphalt mixing plant. The finished asphalt is then loaded.

[0006] Asphalt mixing plants today are predominantly fueled by fossil fuels. In particular, more than 90% of them use pulverized lignite (BKS).

[0007] Asphalt mixing plants are among the energy-intensive industries with high carbon dioxide emissions. Asphalt mixing plants often have an economic classification of 2399, for which appropriate sectoral aid (e.g., carbon leakage) is available.

[0008] Asphalt mixing plants are energy-intensive because they require process temperatures of up to 500 °C to achieve asphalt application temperatures of 110 - 170 °C, depending on the recipe, during the cold addition of the RC.

[0009] An asphalt mixing plant typically produces 50,000 to sometimes 200,000 tons of asphalt per year in an intermittent process.

[0010] With a production capacity of 100,000 tonnes, an asphalt mixing plant requires approximately 6,500 MWh of thermal energy, which corresponds to approximately €290,000 in heating costs (as of 2022). Object of the invention

[0011] The object of the invention is to improve the mixing kneaders according to the prior art in such a way that a method and a device are provided in which the processing of a starting product to a final product is achieved as cheaply as possible, whereby the method and the device manage the processing of a product more efficiently, smaller, more cost-effectively and at the same time also more reliably.

[0012] According to the new Energy Services Act (EDL-G), asphalt mixing plant operators are required to have an energy management system (EnMS) certified according to ISO 50001 starting July 18, 2025. This obligates them to continuously improve.

[0013] In this context, carbon dioxide emissions are also included as a decision-making criterion in public tenders. Solution to the task

[0014] The features of claim 1 lead to the solution of the problem.

[0015] Advantageous embodiments are described in the subclaims.

[0016] The method according to the invention is used for the environmentally friendly operation of an asphalt mixing plant. Currently, asphalt mixing plants are operated using carbon-generating methods. For this purpose, lignite or lignite dust is predominantly burned to generate the necessary heat.

[0017] The disadvantage here is that the exemption from CO2 taxation was decided in 2023, which means that the existing fuel, lignite or lignite dust, has become very expensive and will continue to do so in the coming years. Therefore, continued use will no longer be cost-effective in the future. The current CO2 tax of €45 / tCO2 is already leading to an increase in energy costs from approximately €30 / MWh or €130 / tBKS (2022) to €55 / MWh or €200 / tBKS (2024).

[0018] The planned coal phase-out will further increase costs, leading to further shortages. According to some forecasts, a ton of pulverized lignite will cost over €300 / tBKS starting in 2025. This would increase the heating costs of an asphalt mixing plant to at least €75 / MWh, roughly a threefold increase.

[0019] According to the invention, the energy supplied during operation of an asphalt mixing plant (AMA) is primarily thermal energy, with biomass initially being fed into a pyrolysis plant. Waste heat is generated in the pyrolysis plant, which is then fed into a heat storage unit. The heat storage unit supplies the asphalt mixing plant (AMA) with heat as needed.

[0020] Surplus wood, for example, can be used as biomass. Forest area in Germany accounts for approximately 32 percent of the country, making it one of the most densely forested countries in Europe. However, climate change represents a turning point in forest development. It requires adaptation to climate change and thus forest regeneration, which provides the required wood quantities, as pyrolysis technology can also process "deadwood." Reeds or other waste materials can also be used as raw materials for pyrolysis.

[0021] The pyrolysis plant would generate biochar as a natural by-product.

[0022] One of the advantages of pyrolysis in a pyrolysis plant is biomass conversion / carbon reduction. Pyrolysis produces, for example, so-called biochar, which acts as a carbon sink by storing carbon long-term in the soil, as insulation material, or as a road construction component. Among other things, biochar can be used as a soil improver in agriculture.

[0023] Another environmental benefit is the reduction in greenhouse gases, and the natural waste heat from pyrolysis can replace heat processes using fossil fuels. This reduces carbon dioxide emissions and reduces greenhouse gas emissions.

[0024] Additionally, pyrolysis has a wide range of applications. Various organic materials can be used, such as low-quality biomass, organic waste, some plastics, or even sewage sludge.

[0025] As an alternative to carbon reduction, the by-products of pyrolysis can also be used as biofuels, e.g. renewable bio-oil, syngas or biochar.

[0026] The acquisition, construction, and operation of pyrolysis plants can be expensive, which can impair the technology's economic viability. Precisely because of these existing disadvantages, the use of pyrolysis to generate heat for asphalt mixing plants is not an obvious option. The prejudice in the asphalt industry that pyrolysis does not provide enough heat or energy also needs to be overcome.

[0027] The advantage of using a pyrolysis plant to operate an asphalt mixing plant is that the climate-neutral waste heat can be used.

[0028] In addition, the heat storage system can be fed with electrical heat, with the electrical heat preferably being supplied from grid surpluses. In the future, grid surpluses will be generated, for example, from photovoltaic power in the summer or wind power in the fall and winter.

[0029] With the biochar obtained through pyrolysis, the asphalt mixing plant, which was previously a major carbon dioxide emitter, could now be part of a carbon dioxide storage facility and thus represent a CO2 sink.

[0030] The use of a pyrolysis plant also opens up new business models for operators of asphalt mixing plants, such as the markets for biochar and carbon credits, which are now sufficiently developed.

[0031] The heat storage system allows the continuous pyrolysis process to be coupled with the discontinuous process of asphalt mixing plants, thereby utilizing excess electricity.

[0032] The risk of shortages and rising prices of lignite or lignite dust could also be significantly reduced. This would also make it easier to achieve the objectives of the EU taxonomy.

[0033] The heat storage tank stores thermal energy. For this purpose, the heat storage tank can be filled with rock or a liquid. Another advantage here would be that the heat storage tank could also serve as a district heating unit for nearby households, for example, when the asphalt mixing plant doesn't require thermal energy, for example, because no asphalt is needed in certain phases.

[0034] Separate protection is claimed for a device for carrying out the method according to the invention, in which a heat storage device is arranged between the pyrolysis plant and the asphalt mixing plant.

[0035] Compared to fossil fuels, the waste heat from a pyrolysis plant offers advantages in the operation of an asphalt mixing plant and thus represents a sustainable and economical alternative. Character description

[0036] Further advantages, features and details of the invention will become apparent from the following description of the single figure. Example

[0037] The figure shows an example of an AMA asphalt mixing plant. The asphalt mixing plant is supplied with thermal energy by a heat storage unit (WS). The heat storage unit (WS) therefore serves as the energy source for the AMA asphalt mixing plant.

[0038] Furthermore, it is shown that biomass BM is processed in a pyrolysis plant PYR, where heat is generated from the pyrolysis of the biomass BM. The heat is fed into the heat storage unit WS, which, as described above, in turn releases the heat to the asphalt mixing plant AMA as needed.

[0039] The pyrolysis of biomass BM in the PYR pyrolysis plant produces biochar, biochar, gases, and liquids as byproducts. The PYR pyrolysis plant would therefore generate biochar as a byproduct. The biochar or biochar produced by pyrolysis acts as a carbon sink, allowing carbon to be stored long-term in the soil, as insulation material, or as a component in road construction. Among other things, biochar can be used as a soil improver in agriculture.

[0040] In addition, the heat storage system (WS) can also be supplied with heat in a hybrid manner. For this purpose, excess electrical energy from wind or solar energy, for example, can be converted into so-called electrical heat (E) to supply the heat storage system (WS) with this electrical heat (E).

[0041] In such a case, the electrical heat E would, for example, be supplied cost-effectively from electricity grid surpluses.

[0042] The WS heat storage unit stores thermal energy. This has the advantage of eliminating conversion losses. The heat from the PYR pyrolysis system can be fed directly into the WS heat storage unit.

[0043] The heat storage WS is preferably filled with a rock or a liquid. List of reference symbols BM Biomass PYR pyrolysis plant WS heat storage AMA asphalt mixing plant E Electric heat

Claims

[1] Method for operating an asphalt mixing plant (AMA), wherein an energy is supplied, characterized by following steps: - Biomass (BM) is fed into a pyrolysis plant (PYR); - the waste heat generated in the pyrolysis plant (PYR) is fed into a heat storage unit (WS); - the heat storage (WS) supplies the asphalt mixing plant (AMA) with energy. [2] Method according to claim 1, characterized by that the heat storage (WS) is fed with electrical heat (E). [3] Method according to claim 2, characterized by that the electrical heat (E) is supplied from electricity grid surpluses. [4] Method according to one of the preceding claims, characterized by that the pyrolysis plant (PYR) generates biochar as a by-product. [5] Method according to one of the preceding claims, characterized by that the heat storage (WS) stores heat energy. [6] Method according to one of the preceding claims, characterized by that the heat storage (WS) is filled with a rock or a liquid. [7] Device for carrying out the method according to one of claims 1 to 6, characterized by that a heat storage unit (WS) is arranged between the pyrolysis plant (PYR) and the asphalt mixing plant (AMA).

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