Theoretical Foundations of Chemical Engineering最新文献

Today, the issue of recycling organic waste is very relevant. Unclaimed raw materials can be used to produce useful household products, such as biofuels, which can become a replacement for fuels derived from petroleum products. The basic information on the processing of organic waste into pyrolysis fuel with different moisture content of raw materials by the method of thermal decomposition is considered. Experimental installations for pyrolysis and separation are presented. Experimental studies are carried out on the pyrolysis of pine wood chips with a moisture content of 20, 15, and 10%. The resulting pyrolysis liquid is subjected to a separation process to find out how the moisture content of the feedstock affects the yield of useful products used to produce biofuels. Based on the experiments, it is found that at high moisture content of the feedstock subject to pyrolysis, the total amount of outgoing liquid pyrolysis products will be greater due to the presence of water in them, and the lower the humidity, the lower the total volume. Based on the results of the experiments and the kinetic dependence of the specific mass of the condensed pyrolysis distillate on the moisture content of the feedstock, the histogram of the dependence of the yield of liquid pyrolysis products on moisture and the graph of the yield of the secondary separation fractions in the presence of moisture are constructed.

Negative environmental impacts are becoming more and more significant each year. Electroplating production is one of the largest sources of environmental pollution due to the high content of pollutants in its wastewater. Zinc, nickel, copper, and chrome coatings are most often used in electroplating production; therefore, as a result of the production process, alkaline, acidic, and other forms of wastewater contamination occur. To prevent environmental pollution by industrial solutions and wastewater of electroplating industries, it is possible to use electrodialysis purification. Historically, electrodialysis developed as a desalination method, but recently it has also been used for wastewater separation. The main advantages of electrodialysis are the low cost of cleaning, simplicity of operation, and the lack of the necessity of additional chemicals. In the work, experimental data are obtained on the purification level of an initial solution from Cu²⁺, Fe³⁺, and Ni²⁺ cations. Analysis of the experimental data allows us to establish that the separation process at a current density of 20 A/m² is most advantageous in terms of energy efficiency among the studied separation modes. This separation mode provides almost the maximum purification level with relatively low energy consumption. Based on the selected current density, the economic efficiency of the proposed technological scheme of industrial solution and wastewater purification of electroplating production with a monthly volume of 10 000 m³ is estimated. Calculations show that the cost of cleaning of 1 m³ of wastewater according to the proposed technological scheme is more profitable than the cost of wastewater discharging, even without considering the conservation of water resources. The indicators of the profitability index (PI = 2.3) and the payback period (PP = 4 years and 4 months) allow us to conclude that the project of implementing the proposed technological scheme for cleaning industrial solutions and wastewater of electroplating production is cost-effective and can be profitably implemented in practice.

The article provides a brief description of the key provisions of a mathematical model developed to determine the smoke content of diesel exhaust gases. During the operation of a diesel engine, some of the evaporated fuel condenses into a solid phase, forming dispersed solid soot particles. Depending on the engine operating mode, part of the particle mass is gasified, and part is released into the atmosphere with the exhaust gases. Soot emissions are largely responsible for the harmful effects of diesel on the environment. An analytical description of the soot emission process in a diesel engine is a difficult scientific task, since it is associated with a large number of physical and chemical fast-moving cyclic processes in the combustion chamber. The article proposes a method for determining the function of the average mass diameter of soot particles and the mass concentration of dispersed carbon in exhaust gases, taking into account the specifics of the thermodynamic and chemical processes taking place in the engine cylinder. The results of numerical modeling of the evolution of a soot particle in the engine cylinder are presented, which have practical significance for studying the chemical and physical processes at various stages of fuel combustion in order to reduce smoke emissions from diesel engines.