CFD Design of Waste Heat Boiler Burner in the Education System of Masters Heat Engineering Specialties

Modern CFD methods for calculating combustion processes make it possible to take into account changes in temperatures, heat loads, rates of coolants, as well as further changes in fuel quality. To develop the skills of CFD design and understanding of combustion processes among future specialists in thermophysical specialties, work was carried out to simulate the burner device of a waste heat boiler. For the study, the design of the gas burner of the waste heat boiler RB-70-4.0-440, which operates as a part of the power unit at the LLC “Rubezhansky Cardboard and Container Plant” in the city of Rubezhnoe, was selected. When constructing a geometric model, the hydraulic resistance to the flow of the supply and distribution manifolds was taken into account. To simplify the calculations, the problem was carried out in a two-dimensional, axisymmetric formulation. Analyzing the computational combustion models, the Non-Premixe Combustion model was chosen, which made it possible to take into account the entry of fuel and oxidizer into the reaction zone by two different flows, as well as turbulent diffusion flame propagation. Six variants of models were investigated: the first three variants with a flame tube with a solid disc with diameters of 32, 48, 56 mm, the next three variants, had a burner with a discontinuous disk 32 mm in diameter at a distance of 6, 16, 32 mm from the flame tube. As a result of the research, the optimal shape of the burner was chosen, which corresponds to model 4, and provides a high-quality combustion process, as evidenced by the high temperature of the torch and the lowest temperature at the disk. The conducted research gives future masters the skills of modeling combustion processes in power equipment.

CFD Study on the Physical Behavior of Flue Dust in an Industrial-Scale Copper Waste Heat Boiler

The Flash Smelting Furnace (FSF) is one of the most common reactors for the primary smelting of copper concentrates. Its smooth operation depends on the availability and performance of the downstream Waste Heat Boiler (WHB). The WHB is especially sensitive to problems with its flue dust handling, such as the formation of accretions, which can lead to downtime and equipment failures. Due to the limited accessibility and the harsh conditions of the WHB, experimental studies are challenging. Therefore, CFD simulations can be a promising option to increase knowledge and evaluate a range of options. The present study investigates the physical behavior of flue dust in an industrial-scale WHB via a three-dimensional CFD model. Size-dependent particle sedimentation and the risk areas for flue dust accretions are predicted, finding good agreement with industrial experience and data from the literature. To make the evaluation of accretion risk zones possible, a new sticking function for flue dust is developed. The results are validated against dust samples. Finally, operational recommendations for minimizing flue dust accretions are derived.

Determination of the Design Characteristics of Heat Exchange Equipment for Heating Network Water of a Cogeneration Gas Turbine Unit with a Change in the Heat Load of Consumers in Regions with Different Climatic Conditions

Optimization studies of the dependence of fuel consumption on changes in the heat load of consumers in regions with different climatic conditions and taking into account the determination of the design characteristics of the equipment for heating network water of a cogeneration GTU were carried out. The GTU has two fuel combustion chambers, a waste-heat boiler and a contact heat exchanger for heating of feeding network water. Schematic-parametric optimization studies were carried out on the design mathematical model of the GTU. The analysis of the data of the circuit-parametric optimization made it possible to conclude that for the operating modes of the gas turbine plant with a higher thermal load, it is advantageous to slightly increase the heating surface area of the heater of feeding network water, the cost of materials for the manufacture of which is lower than for the waste heat boiler. This technical solution provided a relatively low increase in specific capital investments with full provision of consumers with electric and thermal energy. The data obtained in this work can be used to select the optimal technical solutions that ensure competitiveness in the operation of a cogeneration gas turbine unit in regions with different climatic characteristics.

Numerical Simulation Analysis of Flow and Heat Transfer in Medium Temperature Boiler

Waste heat recovery by waste heat boiler is one of the important means to utilize secondary energy, which is widely used in metallurgical industry. However, due to the great influence of production technology and other factors in industrial process, it brings many difficulties to waste heat utilization. Based on the structural parameters and operating parameters of the waste heat boiler, combined with the basic principles of fluid mechanics, the numerical calculation model of the waste heat boiler is established. The flow field and temperature field inside the waste heat boiler are studied and analyzed by numerical simulation method, which provides the necessary basis for its structural optimization.

A study of the dependence between fuel consumption of a heat gas turbine and variation of heat loading of regional consumers having various climatic conditions taking into account determination of structural characteristics of heat exchanging equipment for grid water heating

The aim was to optimize the dependence between fuel consumption and heat loading of regional consumers varied due to climatic conditions, taking into account the determination of structural characteristics of heat exchanging equipment for grid water heating in a heat gas turbine. A heat gas turbine comprising two fuel combustion chambers, a waste-heat boiler and a contact heat exchanger to heat makeup grid water was investigated. Scheme and parametric optimization studies were carried out using a mathematic model of a gas turbine created using a software and hardware system developed at the Department of Heat Power Systems of the Melentiev Energy Systems Institute, Siberian Branch of the Russian Academy of Sciences. Th turbine operating conditions differing in heat loads in four suggested operating regions were studied. It was found that an increase in fuel consumption in the second combustion chamber was 29%– 84% compared to that in the first combustion chamber. This rise was recorded when the turbine heat loading was increasing in the considered regions. Data analysis of the scheme and parametric optimization studies showed that, for operating conditions with a higher heat loading, it seems reasonable to ensure the maximum possible heating of makeup grid water as the loading rises. It is also recommended to slightly increase the heat surface area of the makeup grid water heater whose structural materials are less expensive than in a waste-heat boiler. It was shown that the suggested technical solution slightly increases specific capital investments while fully providing electrical and heat power to consumers. The obtained results can be used to select optimal technical solutions ensuring competitiveness in the operation of a heat gas turbine in regions with various climatic characteristics.

Failure analysis of a bearing bush of a feed water pump

BACKGROUND: A rolling bearing bush alloy of a feed water pump that is part of a waste heat boiler of an oil refinery has failed. OBJECTIVE: We try to analyze the reasons that caused the working surface of the bearing bush of the water pump to fall off and then give some suggestions to this failure. METHODS: The composition, microstructure, pit, and crack morphology of the bearing bush alloy were analyzed by the X-ray fluorescent analysis, the energy spectrum analysis, the optical microscope and the scanning electron microscope, respectively. RESULTS: The content of Pb in the bearing bush alloy was high, and the Cu content was low. The primary crystal Cu6Sn5 was low, and the crystal of SnSb with low density moved upward and segregated. The above phenomenon reduced the fatigue resistance of the babbitt alloy. The bearing bush was subjected to alternating loads in service, and several small cracks were generated on the bearing bush alloy working surface. The cracks continued to expand and connected with each other. Fatigue pitting occurred on the bearing bush working surface, a large number of pits were formed, and several large alloy blocks fell off. CONCLUSIONS: The Pb content in the failed bearing bush alloy was too high and did not meet the requirements of the Sn-based babbitt alloys in the national standard. At the same time, the primary crystal Cu6Sn5 formed by Cu and Sn was low due to the low Cu content, and the crystal SnSb with a small density moved upward and segregated. The composition of the babbitt alloy, especially the Cu content, should be strictly controlled to ensure the safe and reliable operation of the bearing.

ANALYSIS OF THE REASONS FOR CRACKING PIPES OF THE BOILER OF THE RECOVERY

8-381X Abstract. Formulation of the problem. One of the main tasks of production is reliable and trouble-free operation of equipment. In the oxygen-envelope process, when cast iron is purged, a large amount of carbon monoxide CO is emitted in the converter, which has a high temperature of more than 1 700 °С of the outgoing gases. The envelope gases in the waste heat boiler are cooled. Converter gas output is characterized by cyclic unevenness In this case, uneven heating of the walls of the boiler pipes occurs. By circulation pumps, chemically purified water is supplied for forced cooling of the boiler walls. When raising the outgoing gases, the cooling water is converted to pars by its subsequent supply to the consumer. The study is dedicated to solving the scientific and applied problem for the reasons for the formation of defects and the identification of cracks in the pipes of the recovery boiler.The purpose of the work. To investigate the causes of the development of transverse cracks in the pipelines of the recovery boiler by various methods of non-destructive testing, to use the methods of scanning microscopy to analyze the microstructure, mechanical tests, and the magnetic properties of structural carbon steel. Conclusions. One of the main reasons for the appearance of massive cracks in the pipes of cylindrical caissons is thermal fatigue caused by high thermal loads. Transverse cracks have the character of thermal fatigue failure, which is confirmed by changes in the ferrite-pearlite structure of the metal, resulting from uneven local cooling of the walls of the caisson. The reasons for the violation of the water circulation in the boiler are the pressure drop in the boiler and a sharp discharge, the load is the release of water from the boiler.