Impact of Waste Heat Recovery of Chimney Using U-Shaped Pulsating Heat Pipe to Generate Hot Water- Experimental and Environmental Analysis

Many studies have been done on the Pulsating heat pipes (PHP) using energy applications system. In this study a heat exchanger PHP is analyzed. A heat pipe prototype is manufactured for waste heat recovery. The present study experimentally investigated the effect of pulsating heat pipe on the waste heat recovery of the chimney and produce hot water for household consumption. The evaporator is placed in a smoke exhaust duct and the condenser is located in a water chamber in which the smoke heat is transferred through. The results are presented for different heat pipe angles to the horizon from 0 to 90. The PHP is filled 60% by distilled water as operating fluid. The highest hot water temperature in outlet of reservoir was about to 58 oC. Also, The CO2 mitigation and CPH of the waste heat recovery system was equal to 84.82 tons and 0.1$/m3. Moreover, the efficiency is changing from 19% for a horizontal PHP to 54% for a vertical one.

Design of Duct Passages for an Air Turbine Starter Test Rig

In a typical air turbine starter (ATS) engine testing application, compressed air is supplied to the turbine by means of an inlet duct usually with a 90 degree bend and discharged from the turbine into the exhaust chimney through a combination of two duct passages. The primary duct is integral to the engine for connecting to the containment ring. The secondary duct is a transition piece for connecting to the exhaust chimney. As these ducts consume additional pressure and adversely affect the performance of the ATS under test. The design of pressure-efficient outlet ducts is therefore essential, and is the topic of present study. The aerodynamic performance of the overall passage depends on the (i) angle of bend, (ii) the shape of the connecting bolt, (iii) the outlet area and shape of the exhaust duct transiting between the bend and the chimney. Combinations of different angular bends, different shaped bolts and varying size of transition pieces are analyzed using the enterprise version of CFD tool, ANSYS. Three dimensional mesh independent simulations using k-epsilon turbulence model are carried out for a combined geometry of inlet duct, rotor-stator combination, outlet ducts together with the bolts. A combination of the duct passages that has resulted in lowest possible pressure drop is suggested as result of the study i.e. the 90 degree bend duct gives 9% pressure difference between inlet and outlet and this might slightly affect the efficiency of the air turbine stator, however the mass flow rate values remains similar to the stator inlet mass flow rate. Hence the 90 degree bend duct is suitable for the test rig. The static pressure loss and total pressure gain is about 0.04% and −0.004% respectively for baseline and aggressive duct of stator and rotor, hence the baseline duct profile is better than aggressive duct. Among different shapes of connecting bolt, the baseline geometry gives slightly lower efficiency of 85.6% when compared to all other models. But due to manufacturing feasibility the baseline geometry is preferred. Exhaust duct model 7 gives pressure drop as 0.062 bar twice the amount of pressure drop in model 6, but it does not affect the efficiency of air turbine starter. The shapes and sizes of the bend, bolts and the transition piece are recommended.

Modern Solutions for the Reconstruction of Gas Exhaust Ducts of Converters Operating in Ukraine

Nowadays most of the installed gas cleaning equipment of oxygen converters of metallurgical plants performs cleaning out of emissions of solid particles with final concentrations higher than acceptable. The inconsistency of the efficiency of the BOF-gas purification with the new emission standards entails the rejection of the emission permit and as a consequences the shutdown of metallurgical plants as well as the loss of the sales markets. In order to prevent the shutdown of the main shops of the metallurgical plants with the simultaneous implementation of appropriate environmental protection measures, it is important to launch the reconstruction of all gas-cleaning units of the converter exhaust ducts. The first element of the BOF-gas cooling and purification system is the BOF-gas cooler, its equipment is in close connection with the process equipment, thus the technological mode of steel production fully depends on its operating mode. The article describes the options of modernization of the exhaust duct of HRSG installed in the BOF-gas cleaning system. Besides, two options of BOF-gas cleaning system presented. In addition, two options of HRSG design: the old one and modernized – were compared.

TEST OF A PILOT INSTALLATION OF A SOIL REGENERATOR FOR GREENHOUSES

The relevance of the development of ground regenerative heat exchangers is determined by the need to save energy resources for heating greenhouses at night and maintaining the required temperature level during the day. The aim of the work is to study working capacity of a ground regenerator for a greenhouse when testing a pilot plant in full-scale conditions. To achieve this goal the following main tasks were solved: experimental research of soil regenerator pilot plant operation was carried out, the heating period of nozzle and cooling period were determined by the obtained temperature curves, the coefficient of intercomponent heat exchange during the heating period was estimated, the rationality of material choice for granulated nozzle was proved, recommendations on improvement of soil regenerator design for industrial use were developed. The research was conducted on a pilot installation of a soil regenerator, which consists of a heat-exchange duct filled with granulated material and covered with a layer of insulation, and ducts with an exhaust duct fan installed at the outlet. Data on air and nozzle temperatures, which were taken during the day, were used to conduct thermal calculations and assess the efficiency of the ground regenerator. It was determined that the heating period at the selected loading mass of 15.5 kg is not long relative to the duration of the experiment and was 166 min. To increase the amount of accumulated heat it is recommended to increase the weight of the nozzle and air flow rate. It was determined that the coefficient of inter-component heat transfer during the heating period varied between 4 W/m2K and 9 W/m2K. In this case, the Bio number is in the range of 0.05 - 0.10, which allows us to conclude that the use of crushed stone as a nozzle material is rational. It is recommended to increase the thickness of insulation to 4.3 cm so that the heat loss from the heat exchange section does not exceed 5%, and to provide the installation of insulated plugs at the ends of the heat exchange section, closing after the end of the heating period.

Study on Methane Distribution in the Face Zone of the Fully Mechanized Roadway with Overlap Auxiliary Ventilation System

An overlap auxiliary ventilation system is very often used for driving roadways in methane-rich coal seams. An overlap zone between the outlets of the forcing duct ends with a whirl flow air-duct (WFAD) and the exhaust duct ends with a dust scrubber that is created by applying the overlap system. This study examines the distribution of methane concentrations at various distances in the overlap zone. Maintaining a long overlap zone could increase the advance of the face. Therefore, the impact of overlap zone length on the methane concentration distribution, in and beyond the overlap zone, is investigated. The evaluation of methane concentrations is performed utilizing a well-established computational fluid dynamics (CFD) approach. The mathematical model of methane emissions into the roadway is adopted. Moreover, the CFD model is validated. A vortex of the return air, caused by the free airstream flowing out of the dust scrubber, is found. This air vortex is responsible for higher methane concentrations at the end of the overlap zone. Therefore, the conclusion can be drawn that maintaining the length of the overlap zone at 5 m to 10 m should be done to control permissible methane concentrations.

Prediction of Pressure Rise in a Gas Turbine Exhaust Duct Under Flameout Scenarios While Operating On Hydrogen and Natural Gas Blends

In recent years, there is a growing interest in blending hydrogen with natural gas fuels to produce low carbon electricity. It is important to evaluate the safety of gas turbine packages under these conditions, such as late-light off and flameout scenarios. However, the assessment of the safety risks by performing experiments in full-scale exhaust ducts is a very expensive and, potentially, risky endeavor. Computational simulations using a high fidelity CFD model provide a cost-effective way of assessing the safety risk. In this study, a computational model is implemented to perform three dimensional, compressible and unsteady simulations of reacting flows in a gas turbine exhaust duct. Computational results were validated against data obtained at the simulated conditions in a representative geometry. Due to the enormous size of the geometry, special attention was given to the discretization of the computational domain and the combustion model. Results show that CFD model predicts main features of the pressure rise driven by the combustion process. The peak pressures obtained computationally and experimentally differed in 20%. This difference increased up to 45% by reducing the preheated inflow conditions. The effects of rig geometry and flow conditions on the accuracy of the CFD model are discussed.

Combustion Turbine Exhaust Duct, Silencer, and Stack Scale Modeling

After constructing a scale model of planned changes to a power plant exhaust system, tests were performed to measure pressure losses in the transition, silencer, and stack. A dimension of 0.30 m (1.0 ft) for the scale model corresponded to 3.7 m (12.0 ft) at full scale. To the extent possible, the scale model tests exhibited geometric similarity with the actual power plant. Total pressure loss coefficients varied between 2.122, 1.969, and 1.932, for three separate scale model configurations that were considered. A combination of turning vanes and splitter vanes in the five-gore elbow, coupled with the use of turning vanes in the rectangular elbow yielded the lowest total pressure loss. Although Reynolds number similarity between the scale model experiments and the actual power plant was not attained, Reynolds number independence was achieved in the tests. The results from this study was applied to model pressure loss in the actual power plant. The scale model testing revealed that utilization of the exhaust ducting design designated as Case A would yield a sufficiently low pressure loss that it would not degrade the performance of the combustion turbine in the power plant to be repaired. Therefore it was selected for inclusion in the retro-fitting of the power plant to facilitate its being quickly brought back on-line.

Prediction of Pressure Rise in a Gas Turbine Exhaust Duct Under Flameout Scenarios While Operating on Hydrogen and Natural Gas Blends

In recent years, there is a growing interest in blending hydrogen with natural gas fuels to produce low carbon electricity. It is important to evaluate the safety of gas turbine packages under these conditions, such as late-light off and flameout scenarios. However, the assessment of the safety risks by performing experiments in full-scale exhaust ducts is a very expensive and, potentially, risky endeavor. Computational simulations using a high fidelity CFD model provide a cost-effective way of assessing the safety risk. In this study, a computational model is implemented to perform three dimensional, compressible and unsteady simulations of reacting flows in a gas turbine exhaust duct. Computational results were validated against data obtained at the simulated conditions in a representative geometry. Due to the enormous size of the geometry, special attention was given to the discretization of the computational domain and the combustion model. Results show that CFD model predicts main features of the pressure rise driven by the combustion process. The peak pressures obtained computationally and experimentally differed in 20%. This difference increased up to 45% by reducing the preheated inflow conditions. The effects of rig geometry and flow conditions on the accuracy of the CFD model are discussed.

Synthesis of Aluminum Foam and Its Application in reducing Noise Pollution in a Gas Power Plant Under Construction

: The noise pollution is among the major challenges of installing the equipment and development of industries. Controlling produced noise in small power plants is a necessity for its development. The present study was conducted to predict the reduction of exhaust noise pollution in a 25 MW gas power plant using the synthesized aluminum foam in a gas power plant under the construction. The noise pollution was measured in a similar gas power plant to predict noise sources in the Tarasht gas power plant. One centimeter thick aluminum foam was synthesized with an average size of about 300 - 500 µm and a porosity of 90%. The impedance tube was used to determine the sound absorption coefficient of aluminum foam. Then, the sound pressure level was predicted by ANSYS software before and after applying aluminum foam in a simulated environment on the exhaust duct wall. Results showed that with the 10 cm of thick insulation layer includes punctuating stainless steel plates, refractory fabric, and closed-cell aluminum foam at high frequency, at least an 8 dB reduction in the noise pollution was obtained the exhaust duct wall compared to the duct wall without the aluminum foam. Aluminum foam can be used as a suitable sound insulator in the power plant industry. Furthermore, it has various advantages over other insulators, such as the resistance to moisture, heat, and vibration attenuation due to noise, proper high rigidity at a low weight, and most importantly, less environmental pollution.