Although Poland is one of the leading recipients of the waste stream in the European Union (EU), it is at the same time below the average in terms of efficiency of their use/utilization. The adopted technological solutions cause waste processing rates to be relatively low in Poland. As a result, the report of the Early Warning and Response System (EWRS) of the EU indicated Poland as one of the 14 countries of the EU which are at risk in terms of possibility of achieving 50% recycling of waste. This article discusses the implemented technological solutions, and shows the profitability of the investment and the values of the process heat demand both for extractor and reactor. The experimental part analyzed the composition of the input and output of the process and compared it to the required fuel specifications. Attention was drawn to the need to improve the recycling process in order to increase the quality of manufactured fuel components. As potential ways of solving the problem of low fuel quality, cleaning the sorted reaction mass from solid particles and extending the technological line with a distillation column have been proposed. The recommended direction of improvement of the technology is also the optimization of the process of the reactor’s purification and removal of contaminants.

The paper describes an installation for the degradative depolymerization of polyolefin materials obtained from wastes, hereinafter also referred to as depolymerization for simplicity. The plant, on an industrial scale, is one of the few operating in Poland. However, it is one of the most modern plants in this industry. Design solutions, construction of particular technological lines, compliance with national and EU regulations and the high level of process safety were described in this paper as well as compared to other plants of this type in Poland. Different solutions were presented in drawings and photos of the plant and in fragmentary technological diagrams. The types of waste and the methods of their processing by the plant were also characterized in accordance with the applicable regulations. The waste throughput is from 2000 to 4000 kg/h, while the efficiency of the depolymerization installation itself is 1500 kg/h. The industrial-scale depolymerization process is carried out in one or two stages: by homogenization (extraction) at a temperature up to 200 °C and depolymerization at temperatures up to 400 °C. The obtained products (energy goods) are sold for further processing. The processes, devices and methods are characterized by novel, innovative solutions, covered by a number of patents, which are also described below. The advantage of the presented technology is the substantial simplification of the process and thereby a considerable reduction in investment costs. Among others, the processes of distillation and rectification (low- and negative-pressure) were abandoned.

The aim of this paper is to present an example of damage to the reheater tubes and conduct the material and numerical analyses to establish the cause of the device failure. Cracks were observed on the first, second, and third tube row. Close to the damaged area, a ferritic structure could be observed with highly degraded bainite areas, characterized by coagulation and coalescence of precipitates. The cause of the damage was analysed using the finite element method (FEM). The big yield of the tube cross-section confirmed that the tube may get damaged during subsequent cycles of the boiler operation, which was also proved by the microstructure testing results. For the reheater under analysis, the tubes have to be lengthened to achieve a reduction in stresses, arising due to thermal loads to values lower than allowable stresses according to Standard EN 13480-3. The modelling results confirmed the correct operation for the upgraded system.

Hanger rods intended for boiler suspensions on a metal structure require a special design approach that considers the total weight of the boiler structure that is to be carried. Unfortunately, a large reserve in the rods’ carrying capacity does not always guarantee the failure-free operation of a boiler. For this reason, it is very important to monitor the forces acting in the rods. Any negligence in this matter might cause a local excess of stresses in the boiler pressure part and result in periodic shutdowns of the boiler. Therefore, in order not to let this happen, adequate computational methods have to be developed. To date, the methods described in the literature and in design requirements have concentrated, first of all, on analyses of the boiler individual subassemblies or on small boiler units supported from the bottom at just a few points. The aim of this paper was to conduct a numerical analysis for a real high-capacity power boiler. The computations were performed based on experimentally measured forces in the hanger rods, and the results were verified by comparing the areas of stress concentration against the area where the boiler structure was regularly damaged.

The paper presents a procedure for assessing the condition of the current structure of boiler tubes. First, a modified version of the Garofalo equation is proposed to model the strain-and-stress state under creep conditions in Super304H steel. In parallel with the creep model development, the microstructure is examined using SEM and TEM techniques. The Super 304H steel structure is tested for a new material and for the superheater material after 100,000 h of operation. According to the presented description of the tested steel degradation, it is possible to operate the material for another 100,000 h if the design conditions are met. The results show that the conventional approach based on European standards does not exclude the superheater safe operation. However, a more detailed analysis, taking account of additional loads from the pipeline and using the proposed creep equation, proves that the conditions for the superheater safety are not satisfied.