Fault-tolerant control system for the formation of carbon products

The production of carbon products is largely resource- and energy-intensive. That is why increasing the efficiency of this production is an urgent scientific and practical task, especially in modern conditions of constant growth of energy costs. An effective way to solve this problem is to create a modern process control system, taking into account possible failures of system components. A method for the synthesis of a fault-tolerant control system for the cyclic formation of carbon products has been developed, which takes into account control errors that are caused by malfunctions of controllers under conditions of unknown disturbances. According to the cyclic nature of the technological process under consideration, a control method with iterative learning was used in the synthesis of the control system. This method considers cyclic processes based on a two-dimensional model (2D model). The proposed control algorithm ensures the convergence of the control process with the task both in time and in each work cycle in order to promote the required quality of control even in the event of unknown disturbances and errors in the performance of controllers. The synthesis of the control system is based on the solution of a system of linear matrix inequalities. Based on the combination of a control method with iterative learning and a control method that takes into account failures in controllers, a method of constructing a fault-tolerant control system for the cyclic formation of carbon products has been synthesized to ensure acceptable operation of the control object in abnormal conditions. The control system has been synthesized by solving a system of linear matrix inequalities with the MATLAB software. In the future, it is necessary to consider optimal settings of the proposed control system and examine its effectiveness in comparison with conventional fault-tolerant systems for non-cyclic processes.

Evaporation of liquids at low temperatures

Ukrainian enterprises annually generate millions cubic meters of mineralized water, which is discharged into surface reservoirs, and millions cubic meters of highly concentrated solutions and suspensions, which are accumulated and stored in special sludge storages. This waste water causes irreparable damage to the environment. A new method for the evaporation of industrial concentrates by fibrous materials with capillary properties was proposed not so long ago. The use of such materials allows an effective, autonomous, cheap, and extremely simple system to be created for the evaporation for various liquids and concentrates. The research methodology was as follows. Two graduated cylinders of the same diameter were used in our research. One cylinder was filled with the liquid phase to a certain level and used to control evaporation from the surface of the aqueous medium. In the other, experimental cylinder, a vertical cotton strip was additionally placed (from 1 to 21 layers of fabric). The width of the strip was 5 cm. The length of the strip was 50 cm. The density of cotton was 100 g/m2. The research method was to determine the height of liquid phase capillary rise along the strip of fabric and to evaluate reduction in the volume of liquid that evaporates in both cylinders at set temperatures. It was found that in the absence of wind and the distance between the vertically placed strips of 7–15 mm were sufficient to ensure the maximum evaporation intensity. Our long-term experiments in natural conditions confirmed the high efficiency of the proposed method. At an average daily air temperature of 2.3 °C, there was a significant evaporation from the surface of the fabric during the day. In this case, evaporation from the water surface was not observed. It should be noted that the intensity of evaporation under natural conditions depends on a significant number of factors (temperature, wind speed, luminosity, humidity, etc.), so it is difficult to detect a direct relationship between some of them. With increase only in the liquid phase temperature, the evaporation efficiency decreased. At a temperature of 20 °C, the laboratory installation (15 layers of cotton strip) increased the evaporation intensity by more than 2 times, at 46 °C by more than 5 times, at 57 °C by almost 3 times, but at 75 °C only by about 67 %. It is obvious that heating of the liquid phase alone less influences the evaporation process from the surface of the fabric strip, which was cooled rapidly in the atmosphere at a much lower temperature. Therefore, to increase the evaporation intensity, it is necessary to increase temperature for all components of the liquid–fabric system. A fabric with suitable properties, stretched between two metal racks and immersed into the liquid phase with the lower end, can be used as a simple evaporator. Our research has shown that the use of materials with capillary properties in the treatment of liquid solutions allows simple, cheap, and efficient devices to be created for evaporating water and converting liquid waste into a solid phase.

Biochar for wastewater treatment – a Minireview**

Wastewater must be treated no matter if is reused or discharged into the environment. The cost of wastewater treatment may be rather high, though other solutions are sought. One of them is the application of filter materials. The filter materials have been used for removal of various pollutants in different kinds of wastewater and a wide range of filter materials (natural products, industrial waste products or man-made products) have been investigated. Among these filter materials, biochar has attracted increasing attention during the last decade. A large number of publications are devoted to production, properties and potential applications of biochar. They reveal that biochar is capable of removing pollutants of different kinds from wastewaters. A number of experiments was focused on the removal of commonly found pollutants, e.g. nutrients, heavy metals, organic matters and pharmaceuticals. It was found that the origin of the feedstock and the thermochemical treatment method are tightly connected and will have an impact on the properties of the biochar. A large number of different feedstock material like wood or wood residues, garden wastes or human and animal wastes can be transformed into biochar by torrefaction and pyrolysis. Properties of biochar will depend on transformation method. Surface area, porosity, pH, surface charge, functional groups and mineral components contribute to a vast number of mechanisms that are responsible for the metal removal, e.g. electrostatic interaction between the surface of the biochar and the specific metal, the cation exchange capacity between metals and protons and the alkaline metals on the surface of the biochar, metal complexation with functional groups and precipitation of metals that form non-soluble compounds. Biochar was successfully applied in wetlands systems to increase the removal of some targeted pollutants.

Evaluation of melt quality during polymer extrusion

Polymer materials are widely spread and used in all industry sectors. The operating properties of polymer products make them practically indispensable in various industries. They have acquired widespread popularity and their production volumes are predicted to grow every year. The extrusion of polymers is one of the main methods for their processing. The melt uniformity is one of the main factors that influence the quality of the products and is determined by the level of mixing, i.e., by the redistribution of additives in a dispersion medium when these additives are introduced into the main polymer. The influence of working conditions, geometry of working bodies and other parameters on the melt temperature uniformity was determined. Nowadays, there are a lot of methods for determining the melt uniformity. They can be used indirectly in or after the extrusion process and can be short or long lasting, which in fact determines the acceptability of each of the methods. To determine the melt uniformity, statistical evaluation methods, which have been verified by many experiments and are well known, are often used. The analysis showed that the mixing index is most sensitive among the criteria described. Although statistical criteria of evaluating the melt uniformity are widespread, it is better to use parameters that allow the state of the mixture to be analyzed directly in the work process for the extrusion of polymers, to identify those that depend on the mixing process. Methods and criteria for verifying the melt quality were analyzed and potential use of their temperature uniformity for measuring and evaluating the melt quality directly in the extrusion process, to eliminate the costly sampling process, was determined.

Decision making in control systems based on data analysis

Technological processes are always accompanied by deviations from the set mode, which is due to the influence of many external and internal factors. The environmental parameters, the components of input raw materials, and the condition of technological equipment are constantly changing, which requires solving the problem of finding the optimal control parameters and, in some cases, the parameters of the process itself. Most industries are focused on obtaining the final product with a given level of quality. Changes in parameters of the technological process may deteriorate the quality of production and cause defects or even emergency situations. To prevent this, forecasting methods are used. The task of constructing predictive models based on experimental data is relevant for a wide range of technological processes. Today, predictive models are widely used in management, diagnosis and identification. The vast majority of these models are based on artificial intelligence technologies or methods of mathematical statistics. The most widespread forecasting models find application in areas such as banking, insurance, business economics, medicine, diagnostics of technical components and equipment, and forecasting the parameters of technological processes. Despite the well-developed algorithm for model development and application, the main problem that remains is to acquire data, select an appropriate model structure, and integrate the model into existing control systems. The paper will predict the parameters of the technological process of methanol production under reduced pressure. The production of methanol under reduced pressure is a multi-stage process, and the emergence of problems at some stage will adversely affect further work and the end result. Note that there are all problems related to the performance of technological processes in the production of methanol, which are described above. Therefore, another task is to forecast emergencies, taking into account the indicators of all stages in the process. The development of models for forecasting emergencies and controlling thermal regimes and their further integration into the existing automatic process control system is proposed to be performed according to the principles of industrial revolution – Industry 4.0. Important components of Industry 4.0 are the Internet of Things, data analysis, and digital duplicates. Each of these components solves a partial problem and, collectively, they provide full automation of production, forecasting of real-time process indicators, and calculation of optimal control. The process of methanol production under reduced pressure can be fully automated in accordance with the components of Industry 4.0. First, there is instrumentation that allows the values of technological process to be obtained over time. Second, given a moderate size of these data, one can obtain models of control objects, perform their software implementation, and use them to calculate optimal control or predict the state of the process. The paper proposes a variant of constructing a virtual model based on experimental data and its further use with actual values ​​of process parameters. A regression model was chosen to develop a model for predicting the temperature regime. Regression analysis allows checking the statistical significance of the parameters, assessing the adequacy and accuracy of the model, and establishing the nature and closeness of the relationship between the studied phenomena. It is also important to predict the occurrence of emergency (adverse) situations at the workplace. For this purpose, it is necessary to determine a list of these situations according to the technological regulations and develop a model for forecasting emergencies. There are various forms of presenting a model for forecasting emergencies. A decision tree is one of them. It will be developed for the production of methanol. The resulting tree is a graphical structure of the verbal (semantic) model relying on the expert's reasoning in solving problems related to emergencies. This is a network structure, whose nodes indicate potential deviations of the control object from the normal mode of operation. The resulting tree is used to solve forecasting and diagnosing problems. For practical use, the decision tree is implemented in software as an "if - then" set of rules. The software is used as an element of a higher-level system in relation to the existing automatic process control system.

Statics simulation of the sulphate iron-containing wastewater neutralization process

At the present stage of technical progress, all industries face an extremely complex problem of creating reliable barriers that prevent the penetration of industrial emissions into the environment. Currently, the issues of stabilizing the quality of wastewater treatment have become especially important in connection with the task of developing wastewater-free industrial complexes. Among the complex scientific and technical problems associated with this task, the problem of stable and reliable maintenance of water quality parameters at the outlet of technological systems is crucial, as leakage of pollutants immediately affects the state of basic production, disrupting its technology and infecting ecosystems. The focus of industry on a sharp reduction in emissions and on the creation of industrial cycles with circulating water supply requires intensive efforts to improve the wastewater treatment technology, the introduction of high-performance processes and devices, as well as the synthesis of control systems for typical wastewater treatment processes. For the performance of automated control systems for typical cleaning processes, it is necessary to develop a software package on the basis of appropriate mathematical models of typical processes. To obtain them, methods of mathematical and simulation modeling and variance analysis were used. In order to assess the quality of modeling, the presented mathematical model describing the statics of the neutralization process for ferrous sulfate water was tested for compliance. To do this, two experiments were performed (the first at an initial concentration of sulfuric acid of 800 [mg/l] and ferrous sulfate of 4000 [mg/l] and the second at an initial concentration of sulfuric acid of 800 [mg/l] and ferrous sulfate of 2000 [mg/l]). First of all, a precondition for the reproducibility of experimental results was verified using the Cochrane test. The mathematical model was verified for adequacy on the basis of Fisher's criterion for the significance level q = 0.05 with degrees of freedom j1 = 16 and j2 = 17. For the first experiment, Grozr = 0.50557 and Gmab = 0.73; i.e., Grozr < Gmab and dispersions are homogeneous. Frozr = 1.0225 and Fmab = 2.4 and thus Frozr < Fmab, and there is no reason to say that the model is inadequate. For the second experiment, Grozr = 0.50308 and Gmab = 0.73; i.e., Grozr < Gmab and dispersions are also homogeneous. Frozr = 1.0005 and Fmab = 2.4 and thus Frozr < Fmab, which also indicates that the model is adequate. The issue related to the performance of technological systems for wastewater treatment in non-stationary modes is directly dictated by the specific operating conditions of treatment facilities, which are expressed by the instability of parameters at their inlet. The inability to apply the necessary technological action to the flow in time is a serious obstacle to the implementation of the cleaning depth, which is guaranteed by the physicochemical basis of the methods incorporated in technological systems and requiring cleaning standards. The operator cannot handle this complex task manually. On the basis of the proposed mathematical model, a structural-parametric diagram of the automated process control system has been developed, which makes it possible to proceed to the elaboration of algorithms and software for the control system necessary for automated control of the wastewater treatment process.

Morphological content and recyclability of separate collected packages: a case study for Kaunas, Lithuania**

Packaging materials can arise from a wide range of sources and are commonly used for food, medicine, household appliances, and items to enclose or protect products during distribution, storage, sale, delivery, and use. The choice of material (paper, plastic, glass, wood, metal, multi-layer or other packaging) to be used depends on the type and properties of product, the purpose of packaging, and the price. The aim of the investigation is to analyse the morphological composition of packaging waste collected separately in Kaunas (Lithuanian) private households and to evaluate its recycling possibilities. The mixture of paper, plastic, and metal packaging waste was analyzed in the winter and spring (one time per month) in the waste management company JSC "Kauno švara".

Block catalytic system for neutralization of carbon monoxide based on aerated concrete

The paper presents the results of a study of catalysts for the conversion of carbon monoxide based on aerated concrete, modified with magnetite and chromium ferrite separately and in aggregate. It was found that at a consumption of 100 g of catalyst powder per 1 dm3 of a typical mixture for producing aerated concrete and obtaining blocks of modified aerated concrete according to the traditional technology, their efficiency is 70-85% at 400 °C and decreases to 9-13% at 200 °C. In terms of strength and physicochemical properties, aerated concrete samples differ little from standard ones, and in some cases even exceed them. The proposed method for fixing catalyst particles in blocks of aerated concrete makes it possible to build fundamentally new schemes for neutralizing carbon monoxide when placing modified blocks directly at the loading of electrode raw materials in furnaces. This greatly simplifies the conversion process and its control system.

Sugarcane biomass as а potential carrier for drug delivery system

Non-steroidal anti-inflammatory drugs are well-known medications for reducing pain and a group of drugs that can cause mucosal damage of the stomach. The negative effects on the digestive system can be reduced by immobilization of drugs on various carriers, for instance, on the components of plant biomass, for the creation of drug delivery system. Plant biomass is a lignocellulosic complex consisting of lignin, cellulose and hemicellulose that can potentially be regarded as a carrier of pharmaceuticals. Sugarcane residues such as bagasse and straw are biomass by-products of the sugarcane industry. One of the prospective ways for their efficient utilization can include chemical processing with the aim of obtaining effective biosorbents or so-called carriers of different composition and structure. The aim of the work was to study the structural, morphological, and sorption properties of cellulose, lignin, and lignocellulose, derived from sugarcane biomass (bagasse and straw) by means of delignification and hydrolysis, as potential components for drug delivery system. Sugarcane straw samples show higher densities in comparison with bagasse samples. Both lignin samples from bagasse and straw have greater bulk and true density if compared to other materials from sugarcane biomass of cellulosic and lignocellulosic nature. The increase in adsorption pore volume in lignins is observed, being indicative of better sorption ability. Both samples of cellulose and lignocellulose from straw have greater pore structure if compared to the initial material. The values of sodium diclofenac sorption efficiency correlate with the values of pore volume for corresponding materials. Lignin from sugarcane straw, which shows greater porosity, has greater sorption properties. SEM images show that the initial materials and treated materials have complex morphology. FTIR spectra show a clear difference in the structure of lignocellulose, cellulose, and lignin from sugarcane bagasse and straw. The potential application of biopolymers from bagasse and straw as organic carriers of sodium diclofenac was studied. With this purpose, plant polymers were impregnated with an alcoholic solution of sodium diclofenac and the desorption process was investigated. The lignin sample from sugarcane straw has a longer period of drug release, which indicates the obtained effect of prolongation.

Investigation of the co-firing of natural gas and RDF in a model combustion chamber**

The production and utilization of fuel derived from municipal solid waste (RDF/SFR) is an effective method for saving organic fuel and decreasing emissions of harmful substances and greenhouse gases at landfill and refuse dumps. Ukraine has a potential for the production of 1.5–2 million tons of RDF/SFR with a calorific value of 10–25 MJ/kg annually. In the case of involving these fuels to power sector, about 2500 GW-h of electricity and 4500 GW-h of heat can be produced annually. One of the promising variants to involve RDF/SFR to power sector is their combustion, including co-firing with natural gas, aimed at the production of heat and electricity, in particular, using the existing boilers of small and middle steam capacity in compliance with stringent ecological requirements (Directive 2010/75/EU etc.). For performing this investigation, we chose a GMP-16 gas-and-oil-fired burner, mounted into a cylindrical combustion chamber. The gas-and-oil-fired hot-water boilers of KVGM grade, designed for heating and hot water supply, are equipped with burners of this type. In computer modeling, we determined the influence of RDF additions on the co-firing with natural gas for a given geometry of the combustion chamber components (with a burner of 18.6 MW heat output). We obtained calculated dependences of temperatures, velocities, distributions of gas component concentrations, carbon remained in the solid phase, as well as the concentrations of nitrogen oxides and carbon monoxide over the combustion chamber. According to preliminary assessments, we established that additions of up to 20% RDF/SFR (by heat at input) in their co-firing with natural gas will not change substantially the technical and ecological parameters in operation of the combustion chamber.