English
Search
Dear business partners!
The smallest division of the parent company was established in 2011 as a logical consequence of the development of ROEZ and the formation of the production division. The original focus of the smallest department in that time was on strength calculations and FEA analyses. Over the years, the services of the division, however, has been extended to the areas remote from the specialized calculations. With the increasing complexity of products and services of the parent company, especially for the nuclear industry, the division has extended its service portfolio. There has been a progress from the strength calculations to proof documentation and from the seismic calculations to the equipment quali-fications for the complex requirements by type testing. Nowadays, qualifications of equipment for various technical and legislative requirements have a fixed place in our activities. By expanding the company‘s portfolio of products and services in recent years, the division has moved from a detailed assessment of individual components to designing energy and chemical systems. Today, after several successful solutions, the offer of our services is enriched by principal design and optimisation of such systems. Innovation is most likely the right word to characterize division, its past and present as well. Behind the development of the division and the dynamic growth of the offered services is a collective intention to look beyond the standards and commitment to expand knowledge potential. Just this approach determines the position of the division within ROEZ: we are at the heart of atypical and demanding technical solutions. The division has successfully embarked on projects that, due to their nature and complexity, belong to the field of research and development. The long-established innovative approach of the team around me has discovered possibilities, sometimes has determined the trends of development and has also given the knowledge potential necessary for a successful solution.
Yours sincerely, Igor Istenes
The division‘s staff is almost without exception graduates of applied mechanics from faculties of mechanical engineering and are particularly strong in the field of FEA/CFD analyses. In the field of analyses, we benefit from more than 20 years of experience and this area, from which the division‘s knowledge potential has grown, forms the foundation of our expanded activities which are (re)qualifications and system solutions. Although it may be surprising to say that calculations may be the starting point for such a route the opposite is true. Each calculation of equipment begins with the analysis of the system whose it is a part, its construction and operating conditions, load conditions, the possible impact of the medium, the presence of chemistry, vibration and the environmental impact: the objective is to identify possible degradation mechanisms affecting the system during its service life. Knowledge of technical requirements, along with the legislative framework and the set of applicable standards, has implicitly created the basis for extending our services to qualifying special purpose devices (especially for the nuclear industry), lifetime extension of operated equipment as well as for the design/optimisation of energy and chemical systems. The fields of our activities are closely linked and, in most cases, the solution requires the discussion and cooperation of the division‘s teams. Division R&D has the so-called flat organizational structure. Within the division the relationships are open, mutual and characterized by many interactions during the solution of technical problems. In our solutions we cooperate primarily internally, with colleagues from other divisions of the parent company as well as externally, especially with testing laboratories. Any complex solution, especially with nature to research and development, is based on intensive communication of our ideas and results within the company, towards external collaborators and, in particular, towards the end customer.
Design and optimisation of complex energy and chemical systems:
Assessment of serviceability and lifetime extension of energy and chemical equipment:
Assessment of serviceability:
Lifetime extension:
Qualification of equipment for specific operating conditions and working medium:
Advanced FEA/CFD analyses:
To characterize the activity and approach of the division‘s work, we present two typical solutions that combine all the elements characteristic of R&D. Reference solutions illustrate the division‘s innovative approach and illustrate division‘s core business to solve complex technical problems.
At the beginning of this successful solution, there was a request to assess the serviceability, lifetime and functionality of the quick-acting main steam isolation valves of dimensions DN450 and DN500 (MSIV) installed at the nuclear power plant (NPP). MSIVs are safety valves designed for high energy line break of the main steam distribution system (HELB event). Their task is to separate the broken part of the pipeline from the secondary circuit in max. 5 seconds. MSIVs are, from a structural point of view gate valves operated by a pneumatic actuator fed from air tank. Under normal operating conditions, the MSIVs operate at a temperature of 262°C and line pressure 4.8 MPa. The actuator operating air pressure is 4.5 MPa.
The assessment of serviceability included analysis of possible degradation mechanisms, factors affecting safety function, dimensional, visual and non-destructive inspection, computational analyses FEA/CFD when valve closing to full me-dium flow. As the result of the requalification, it was stated that the service life of the valves could be extended to the end of the planned service life of the NPP but there is a possibility for increasing reliability when safety function is ensured (i.e. in the case of emergency closing to full medium flow).
Based on the results of the requalification, the idea of upgrade led into preparation of the feasibility study. The proposed upgrade was an investment-attractive alternative to the replacement of valves with new equipment. The operator acquired the idea of the proposed reconstruction and thus created space for the development of the reconstruction technology.
The development of reconstruction technology required the projection of the ideas of upgrade into design drawings and technological processes. The R&D division participated in every step of the design works (basic design and dimensioning, strength calculation and detail design of the new actuator) as well as the development of welding technology (selection of filler metals, development of the single-purpose welding machines, optimisation of welding/hardfacing technology). The developed reconstruction technology was used to upgrade the prototype, which, in addition to verifying the feasibility of the proposed upgrade, also served for the purposes of the qualification tests.
In accordance with legislative and qualification requirements, the qualification documentation was prepared by the division. Qualification of upgraded MSIV was based on analyses (FEA/CFD devoted to seismic resistance and functionality when closing to full medium flow), type tests and also operation experience (e.g. aging of non-metallic parts). The prototype was subjected to seismic type test on stand and subsequent test of functionality using a hydraulic equipment (designed in the division for the purpose of functionality test).
The prototype was upgraded under workshop conditions. The transfer of the technological skills acquired during its reconstruction to the “on-site conditions” was the last challenge. Limited space and time for the upgrade of three MSIVs during the NPP shutdown was manageable only by coordinated technical training and on-site assembly.
The development related to upgrade of MSIVs is the one of the best illustrations of the activities offered by the R&D division. The initial request for the requalification of the equipment was projected into the proposal of reconstruction. The principal idea of reconstruction was projected during two years of development in the division into the technological process applicable in the “on-site conditions”. The result of the development was the upgraded prototype of MSIV whose conformity with technical requirements was demonstrated by qualification using type tests. At the same time, the knowledge potential necessary was provided by the division at any stage of the solution, from calculations to technical support for on-site assembly work.
The customer‘s request was to modernise the ammonia production line by replacing the ammonia reactor. An increase in the efficiency of the entire production line was required, taking into account as much as possible the specificities of the existing production line as a whole. On the one hand, a modern and efficient reactor was expected to be designed but on the other hand without the chain effect of extensive changes in unaffected parts of the plant.
The first step of the solution was to analyse the existing system of ammonia production line and to build of its mathematical model. The model of the system enabled to analyse the impact of changes in reactor‘s construction and parameters during its design on the system as a whole. This made it possible to monitor the impact of reactor changes on the rest of the system during an iterative design.
An ammonia reactor is an equipment where high-pressure synthesis gas passes through individual catalyst beds on which nitrogen reacts with hydrogen in an exothermic reaction to produce ammonia. The design of the reactor itself offers a number of parameters and variables, the choice of whose determines the efficiency of the reactor and, of course, also affects the system as a whole. The number of catalytic beds, the type of reactor cooling, the gas flow through the catalytic beds, the catalyst grain size and other parameters determine the final reaction efficiency. The main tool of reactor design optimization was the CFD analysis, based on which the final design of the ammonia reactor was proposed.
The process design of the ammonia reactor with respect to the operator‘s requirement was part of the iteration cycle where the impact on ammonia line components was evaluated for each intermediate design of the reactor. Using the mathematical model of production line as whole, an optimum compromise solution was proposed after a number of iterations. As a final result, a
modern and efficient ammonia reactor can be implemented with minimum component changes in existing production line.
The design of the ammonia reactor is a great illustration of the system solutions offered by the R&D division. CFD analyses of the complicated chemistry of process design and ammonia reactor optimisation was applied in the mathematical model of production line and as a result optimal design was achieved using iterative process of evaluating the impact of changes on the system as a whole