Afterburner Chamber Research Articles

ОПЫТ ТЕХНИЧЕСКОЙ ЭКСПЛУАТАЦИИ ПРОКАЛОЧНО-УТИЛИЗАЦИОННОГО КОМПЛЕКСА "РУСАЛ ВОЛГОГРАД"

The paper presents the main directions of the integrated approach to ensure the reliability of the operation of the Rolling and Utilization Complex for the production of calcined petroleum coke. During the period of operation since 2018, RUSAL Volgograd specialists have implemented a number of design solutions to improve the afterburning chamber and gas duct system, and also selected a new composition of lining based on mullite refractory to increase its durability. The obtained results provide the possibility to increase the productivity of the equipment up to 5 % with obtaining calcined petroleum coke of stable quality.

Numerical investigation of thermo-acoustic instability in a model afterburner with a simplified model for observed lock-in Phenomena

Thermoacoustic oscillations in a gas turbine afterburner are numerically investigated using CFD. A simplified 2-dimensional axisymmetric afterburner with bluff-body stabilized flame is considered in the investigation. Occurrences of both low and high-frequency thermo-acoustic oscillations in the afterburner chamber are observed at specific fuel flow rates. The flow field from the CFD shows the bluff-body vortex shedding frequency to lock-in with the acoustics of the chamber during the thermo-acoustic oscillations. The synchronization and lock-in of bluff-body wake with chamber acoustics happen with increase in fuel injection rates resulting in thermoacoustic coupling. The Proper Orthogonal Decomposition of the flow field revealed the presence of chamber acoustics in the pressure field confirming the coupling. Then a simplified mathematical model based on the van-der Pol oscillator is attempted to reproduce the observed lock-in behavior of the bluff-body wake. The chamber acoustic field is considered as the forcing term for the simplified oscillator. The oscillator model qualitatively captures the synchronization of the flame-holder wake oscillations with the chamber acoustics. This model could be extended to combustors with bluff-body wake in predicting the thermo-acoustic oscillations.

Fire risk problem of aluminum foundry

During various modes of operation of the melting furnace, a large amount of aerosol particles consisting mainly of amorphous carbon is generated irregularly depending on the current state (especially during the loading of the return material), accompanied by the development of significant amounts of volatile organic compounds and methane. The resulting mixture of organic substances is not quantitatively eliminated in the afterburner chamber of the melting furnace. The VOC mass flow remains almost unchanged and only the methane mass flow decreases. The mass flux of aerosol particles, on the other hand, increases after passing through the afterburner chamber, with particles of aluminium metal contributing significantly to this increase. The aerosol particles trapped on the textile filter of the melting furnace are thus composed of particles of amorphous carbon and particles of inorganic origin (metallic aluminium and limestone). The structure and surface properties of the carbon particles pose a significant risk of textile filter ignition. From the measurement results obtained, the following solution to the hazardous condition of the plant can be found: (a) a change in the existing technology, for example: changing the design of the part of the melting furnace into which the return material is fed; changing the heat input and the mode of the gas burner and fan in this part of the furnace; a significant reduction of the flue gas flow in the A-gauge and afterburner chamber or change of machining emulsion; (b) the installation of an additional gas burner in the newly installed afterburner chamber, to which the flue gases from the part of the melting furnace into which the return material is fed would be discharged in the existing return material inlet mode.

Effect of Hard Coal Combustion in Water Steam Environment on Chemical Composition of Exhaust Gases

This academic paper revolves around the results of research on the change in emission parameters of the used heating boiler following the introduction of the overheated water stream, which had an impact on different emission parameters. The research results provide an insight into the hard coal combustion process, which had a significant impact on the change in the chemical composition of exhaust gases: it contributed to the lower mass concentration of the emitted dust and black carbon (PM) as well as nitric oxides (NOx) while, at the same time, playing a significant role in increasing the mass concentration of the emitted carbon oxide (CO). Two types of devices were used for the purposes of conducting the research at hand: a boiler with an automatic fuel feeding system with one combustion chamber and a boiler with a combustion chamber and an afterburning chamber fitted over it. Apart from the measurements of mass concentration of the emitted harmful substances, the research also focused on measurements of temperature inside the combustion and afterburning chambers, as well as the temperature of exhaust gases and their oxygen content. As part of the research, water steam was introduced to the combustion and afterburning chambers at the flow rate of 0.71 kg/h and 3.60 kg/h for boilers operating at a minimum power of 30% and a nominal power of 100%. An original steam generator with an overheated water steam production range from 0.71 kg/h to 3.60 kg/h was used to create and feed the water steam. The efficiency of the combustion process was calculated using the obtained results for each operating configuration of a given boiler.

Numerical analysis of afterburner chamber design for solid oxide fuel cell system

This article applies computational fluid dynamics (CFD) to investigate the thermal and flow fields in the afterburner of solid oxide fuel cell (SOFC) systems. The objective is to estimate the performance of the burner to serve as a reference for performance improvement through structure design. The elliptical baffled burner, which enhances the effect of convective heat transfer and temperature uniformity effectively and suppresses the NOx formation as well, is proposed in this work. Additionally, low residual fuel exhaust and pressure drop are achieved. These advantages make it highly capable of being adopted in the industrial and commercial SOFC systems. The fuel of lower caloric value causes decreases in temperature and generation of NOx in the burner as the stack fuel utilization increases. For a 25 kW SOFC system, the stack fuel utilization of 80% reduces exhaust temperature by 65 K and NO emission by 38% than that of 70%.

ПРОЕКТИРОВАНИЕ ТЕПЛОЗАЩИТНОГО ЭКРАНА ФОРСАЖНОЙ КАМЕРЫ СГОРАНИЯ СОВРЕМЕННОГО ТРДДФСМ

In this article, the design of the heat shield of the afterburner chamber of the aircraft turbofan engine is proposed, which allows to improve its characteristics. This design makes it possible to change the material of the heat shield from deformable al-loys to heat-resistant cast alloys with higher operating temperatures and lower density. Based on this, a 3D solid-state geomet-ric model of the afterburner with an upgraded heat shield was developed. The hydraulic calculation of the afterburner and its cooling channel is carried out according to the engineering method. At the same time, the burning process in the afterburner was simulated in full forced mode using the Ansys CFX software package. The data obtained because of modeling and engi-neering calculations are analyzed and compared with each other by the flow rate of air passing through the gaps between the sections of the heat shield for its cooling. As a result of the calculation, the integral characteristics of the afterburner and the de-veloped design of the heat shield are obtained. To check the efficiency and operability of the resulting design, the refining thermogasodynamic calculations of the engine with the upgraded afterburner were carried out on two typical engine operating modes: maximum and full forced. To assess the impact of changes in the characteristics of the upgraded afterburner on the main characteristics of the turbofan engine using the DVIGw simulation system. As a result of the calculations, it is obtained that the use of a heat shield of a promising design allows you to reduce the weight of the screen itself by 9% and increase the thrust of the entire engine by 1% at maximum and full forced modes in general.

Numerical study of a heat transfer process in a low power heating boiler equipped with afterburning chamber

The paper presents a numerical study of a heat transfer process realized in a three draughts low power heating boiler for solid fuels combustion equipped with an afterburning chamber. The main reason for the proposed research is to define the character of an exhaust gas flow through the special construction of heating device at different levels of the heat loading. Heating boiler construction allows for dividing stream of the flue gases into two separated streams. One part of the stream is transferred directly to the afterburning chamber and omits first two draughts of the heating boiler, where the rest of exhausts is directed to. Authors simulated the limitation of exhaust streams division into the afterburning chamber in order optimize the heat transfer process. Obtained results showed that the character of exhaust gas flow strongly depends on the amount of heating power of the heating device. Changes in exhaust gas flow caused increasing of heating power obtained for the nominal load by 4.2%. Similar effect was not visible during heating boiler work with minimal level of the heat load.

Numerical Study of Micron-Scale Aluminum Particle Combustion in an Afterburner Using Two-Way Coupling CFD–DEM Approach

Metal additives have positive effects on the flow field such as increasing the temperature and thrust, while this may decrease local gaseous velocity due to inter-phase drag forces on the other hand. An in-house computational solver was developed to study the typical multiphase flow with combustion. The solver relies on Eulerian–Lagrangian model and the two-way coupling approach. Numerical simulations were carried out on an afterburning chamber of a solid-fuel ramjet to study the impact of using aluminum particles as metal additive. For micron-scale aluminum particles, the injection area, initial temperature, diameter and mass flow rate are varied influence factors, while the afterburning chamber and inlet primary high-temperature gases are fixed for all the test cases. It was found that better particle dispersion can result in higher combustion efficiency due to increasing the gas-particle contact area as well as better heat transfer and diffusion. Injecting aluminum particles with higher initial temperature and smaller diameter tend to get ignited faster and then burn more easily, which means releasing more heat in the length-limited flow field. However, the aluminum particle massflow rate has much more complicated comprehensive influence than the changing rules of the adiabatic combustion temperature based on the NASA CEA code.

Evaluation of Effectiveness of Solid Fuels Based on High Enthalpy Dispersants for Rocket Ramjet Engines

The possibility of replacing the currently widely used ammonium perchlorate as an oxidizing agent (dispersant) in the composition of solid boron-containing fuels for aircraft with rocket ramjet engine was considered by dispersants with reduced nitrogen and oxygen content with a high enthalpy of formation (more than 2 MJ kg−1) and capable of gasifying solid fuels. The efficiency of fuels with high enthalpy dispersants was evaluated in an optimization setting according to the flight range criterion of the aircraft taking into account the complete combustion of fuel in the afterburner chamber. A number of the most effective dispersants were recommended for further study.

Ignition kinetics of boron in primary combustion products of propellant based on its unique characteristics

Study on the boron-based primary combustion products can bridge the gap between primary combustion and secondary combustion in solid rocket ramjets. To clarify the initial state and ignition characteristics of boron particles in the after-burning chamber of solid rocket ramjets, the elemental, composition and morphology of the primary combustion products collected under gas generator chamber pressure of 0.2MPa and 6MPa were investigated by energy dispersive (EDS), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy with energy dispersive (SEM-EDS) individually. The ignition times of boron particles among the primary combustion products were determined using a high temperature tube furnace system. The BD model was adopted for numerical verification. The numerical solution procedure of boron ignition model in a real afterburner chamber was modified. The results show that the sum of B, C, O elements in the primary combustion products reaches approximately 90%. The primary combustion products are mainly consisted of B, C, and B2O3. Images of the primary combustion products present highly agglomeration, indicating an oxidation of boron surface. Numerous spherical carbon particles with a diameter around 100nm are observed in the products. Three features of the boron in the primary combustion products are obtained, compared to virgin boron. First most of the boron lumps are covered by carbon particles on the surface. Second the mean particle size is five times larger than that of virgin boron. Third the overall initial oxide layer covered on boron surface increases its thickness by above 0.1µm. The ignition time of boron in the primary combustion products reaches 20–30ms under 1673–1873K, which is quite different from virgin boron of ~4ms. Numerical calculation results show the key reason leading to such a long ignition time is the variation of the initial oxide layer thickness. In conclusion, the physicochemical properties of boron particles are found to differ with virgin boron after primary combustion process. The accurate evaluation of the initial oxide layer thickness and initial particle radius is a crucial procedure before the numerical calculation of boron ignition kinetics. Results of our study are expected to provide better insight in the simulation of solid rocket ramjets working process.

Ignition and combustion of pyrotechnic compositions based on micro- and nanoparticles of aluminum diboride in air flow in a two-zone combustion chamber

This paper presents the experimental study of ignition and combustion of micro- and nanoparticles of aluminum diboride as part of pyrotechnic energy-saturated compositions in a gas generator with an air afterburner chamber and the thermodynamic calculations of combustion of pyrotechnic compositions based on aluminum diboride in air. The discharge of the combustion products from the afterburner chamber is recorded on video. It is shown that replacing micron aluminum diboride by powdered diboride with a mass-average diameter of particles equal to ≈270 nm in the pyrotechnic composition and increasing the pressure in the afterburner chamber cause the combustion efficiency in air to increase by 5–20%.

Incineration of animal by-products – The impact of selected parameters on the flux of flue gas enthalpy

This paper presents model analyses and tests of animal by-product waste thermal treatment plants. A schedule of tests was prepared, and 62,024 cases of system operation were analysed. A map/work field of the tested plant was drawn up on the basis thereof. Calculations were made following an algorithm described by Bujak (2015a) written in the VBA (Visual Basic for Application) language. The tests showed that when incinerating animal waste, the flux of physical enthalpy of the flue gas from the afterburner chamber depends on numerous design and operating parameters. The most important include the following: humidity and flux of the waste, concentration of oxygen in the flue gas in the afterburner chamber and loss of heat flux to the atmosphere through the external surfaces of the plant. Individual design and operating parameters can be selected so that the process of incineration is ensured without additional fuel. The performed analyses were verified against the actual object at the industrial scale using a meat plant that manufactures ham and processes beef, pork and poultry with a capacity of 150tonnes/day. The production process waste included mainly bones and – in much smaller quantities – meat and bone meal, at 17tonnes/day. The performed tests and analyses can be used to optimise the operation of the waste thermal treatment plant at the stages of design and operation.

Computer-aided design of aircraft gas turbine engines and selection of materials for their main parts

The problem of aircraft gas turbine engine computer-aided design is dealt with in the article. An expert system for the selection of materials, coatings and other kinds of preparing surfaces of the main components and assembly units of the aircraft gas turbine engine flow section at the design stage developed on the basis of thermogasdynamic simulation modeling of DVIGw aviation engines is described. The system performs thermal gas calculation of the engine and its main components, develops the most likely structure of the main parts, estimates the thermal state of air-gas channel elements, makes an approximate strength prediction of the main elements and assembly units, analyzes the applicability of the materials from the developed database, generates the list of the most applicable materials, offers possible variants of coatings and heat treatment conditions. A topological model of two-spool mixed flow turbofan with an afterburner chamber for military high-maneuverability aircraft in the developed expert system is presented in the article. Some results of modeling and choosing materials for the main engine parts are presented. It is shown that the expert system can analyze both metallic and composite materials. For composite materials a unidirectional orthotropic composite material is designed on the basis of the composite materials database and its properties at the existing flow temperatures are predicted. The main advantage of using this method is time and labor saving in the process of designing new aircraft engines and their main parts.

Effect of plasma on boron-based two-phase flow diffusion combustion

A parallel intake diffusion combustion physical model is designed to study the influence of plasma on the secondary combustion of boron-based gas in the after-burning chamber, with excluding mixing effects of the intake air. The flame images of the diffusion combustion of the boron-based gas in the after-burning chamber are obtained by a high-speed photographic apparatus. The diffusion combustion characteristics of the physical model and the secondary ignition distance of boron particles are analyzed. The King ignition model, finite-rate/eddy-dissipation model, particle-trajectory model, RNG k-ε model, and plasma model are adopted to simulate the influence of plasma on the diffusion combustion of boron-based two-phase flow in a certain condition. The results show that the secondary ignition distance of boron particles, which is based on the boron-based flame image, is consistent well with the numerical simulation result, which verifies the accuracy of the boron-based two-phase flow diffusion combustion numerical model and the calculation method. When the boron-based gas passes through the plasma area, the temperature of the boron particles increases while the diameter decreases significantly on their trajectory. The distribution area of the B2O3 mass fraction increases significantly, and more than 70% boron particles reach a 100% combustion efficiency before they arrive at the area of the two-thirds after-burning chamber. More heat is released by fully burning the boron particles under the influence of plasma, which results in a half increase of the central area. It can be indicated that plasma can obviously enhance the combustion process of the boron-based gas, which improves the combustion efficiency of boron particles and releases more energy.

Numerical Simulation on Two Phase Combustion Characteristic in Solid Rocket Ramjet Afterburning Chamber

Numerical simulation on two-phase combustion characteristic in afterburning chamber of solid rocket ramjet was carried out by applying particle trajectory model. It was analyzed that the nozzle number of secondary combustion chamber, inlet angle of air and particles diameter impact on efficiency of combustion. Results show that the combustion efficiency in the afterburning chamber is highest, achieving 99.6% when the angle between both air inlets is 180°, particle diameter is 15μm, and 5-hole nozzle is used. By contrary, when the angle between both air inlets is 90°, particle diameter is 5μm, and 5-hole nozzle is used, the afterburning chamber has a lowest combustion efficiency of 70.3%.

Determining the maximal capacity of a combined-cycle plant operating with afterburning of fuel in the gas conduit upstream of the heat-recovery boiler

The effect gained from afterburning of fuel in the gas conduit upstream of the heat-recovery boiler used as part of a PGU-450T combined-cycle plant is considered. The results obtained from calculations of the electric and thermal power outputs produced by the combined-cycle plant equipped with an afterburning chamber are presented.

Analysis of using gasification and incineration for thermal processing of wastes

The contribution discusses the possibility of utilising gasification as the first part of a two-stage waste thermal treatment technology. The application of gasification brings a number of improvements over the conventional oxidising approach. These include e.g. the fact that the primary thermal waste decomposition is performed under temperatures below the melting point of the ash material as well as that substantial savings of the auxiliary fuel in the after-burner chamber are achieved by exploiting the heat value of the gasification products. In experiments gasification specifications and composition of products are studied. The gasification was carried out within the temperature range 800–860 °C and in the presence of air entering at stoichiometric ratios between 0.15 and 0.25. The waste was mostly a mixture of shredded textiles and rubber, with a heat value of 33 MJ/kg. The model equipment could treat maximum 40 kg of waste per hour. Based on the results of the waste gasification testing, heat and mass balances of the incineration plant with capacity of 10 kt/y of industrial waste were evaluated and the results compared with conditions required in an incineration plant operating under an oxidation regime.

Processing of waste from pulp and paper plant

Production of sludge as waste in pulp and paper plants can be considered as one of the serious environmental problems that have to be solved. While landfilling is not a suitable solution from the environmental point of view, thermal treatment proved to be the most appropriate one. This paper describes an efficient way of processing sludge including waste-to-energy aspects. A thermal treatment unit with a capacity of more than 100 tons of wet sludge per day had been built in a large pulp and paper plant some years ago. This pulp and paper plant is located in a mining area. When built, this unit was quite modern. However, because of more and more sweeping environmental laws affecting the process industry, the unit needed a complete retrofit. The retrofit has been realised in three stages. A brief description of the unit for the thermal treatment of sludge is as follows: the waste sludge (after transport from a sludge storage system) is burnt in a multiple hearth incinerator with a fluidised-bed chamber. Then, the flue gas enters a secondary combustion chamber (afterburner chamber). During the first stage of retrofit, only a part of heat from flue gas was utilised for heat recovery (pre-heating air for combustion and fluidisation) and a contact cooler was involved in the unit. The second stage of retrofit can be characterised as a “waste-to-energy” one. The contact cooler was replaced by a system for preheating water for steam generation. Off-gas cleaning system consists of a filter for particulate removal and a three-stage scrubber system. (Several alternatives of retrofit were considered and simulated and the most promising one was selected.)

Numerical simulation of flow-field and dioxins chemistry for incineration plants and experimental investigation

The development of incineration units (kiln and afterburner) for hazardous wastes in terms of design and fluid-dynamic optimization has been carried out together with definition of a new design methodology. An extensive theoretical and experimental analysis has been carried out on a hazardous waste incineration pilot plant to test the methodologies and to optimize the entire system in terms of reduction of the polluting emissions and higher combustion efficiency. In particular, the combustion chamber and the afterburner have been thoroughly studied. A computer code for multiple chemical reactions occurring in an afterburner chamber of an incineration system was developed, based on the equations presented herein, to evaluate the decomposition rate of dioxins for different chamber geometries. The results of these analysis are presented herein.

Influence of sludge cake concentration on the operating variables in incineration by different types of furnaces

The influence of cake concentration on fuel consumption, air requirement and flue gas production in incineration of sewage sludge is discussed. Fluidized bed (FBF), multiple hearth (MHF) and rotary kiln (RKF) furnaces are considered as alternatives together with the optional use of an afterburning chamber where exhaust gases are taken at 950°C for 2 s with an oxygen concentration of 6% by volume. It clearly appears that, if an afterburning chamber is used, and total minimum fuel consumption can be achieved at an optimal value of cake concentration (45.9% for FBF and 32.5% for MHF) when autogenous conditions are reached in the furnace and air addition is no longer needed in the afterburning chamber. At higher concentrations, abundant exhaust gas productions, due to the dilution air needed in the furnace, can considerably increase fuel consumption in the afterburning chamber, especially in MHF operation. In the rotary kiln furnace, fuel requirement decreases over the whole range of cake concentration as no conditions for autogenous combustion in the furnace can be achieved.