Effect of Sorbent Physical Structure—Pore Size Distribution and Surface Morphology—on the Limestone Capability for Sulfation

Sulfur oxides are present in the gases from burning coals and these pollutants are harmful to the environment. Sulfur removal in the fluidized bed reactor applying limestones is an efficient technology. During sulfation, the formation of CaSO4 leads to the partial or complete blockade of the particle interior, resulting in a low efficiency of the use of limestones. As the desulphurization capacities of the sorbents are strongly affected by thermal condition, this paper focuses on the study of the development of the particles’ physical structure before and during sulfation reaction. The experiments were performed for two Brazilian limestones, a calcite and a dolomite. The particles were well characterized by BET analysis and mercury porosimetry and the behavior of the sorbents was observed through thermogravimetry analysis (TGA). The morphological analysis of the surface of both raw calcite and dolomite particles indicated that dolomite was a less compact sorbent. However, after calcination and sulfation, the change in pore and voids distributions showed that for dolomite both swelling and partial pore filling could take place, whereas for calcite the spaces between particles were maintained constant, possibly owing to a less intense swelling. In 30 min of reaction under air atmosphere TGA measurements provided conversions of 0.40 ±0.061 for the calcite, and 0.55 ±0.089 for the dolomite. The results showed strong dependence on meso and macropores region with high conversion of the sorbents. The reactivity differences between calcite and dolomite can also be explained based on the swelling of the particles.

Ambient Condition Effects on NOx and CO Emissions From Process Heaters

Because process heaters are typically located outside, their operation is subject to the weather. Heaters are typically tuned at a given set of conditions; however, the actual operating conditions may vary dramatically from season to season and sometimes even within a given day. Wind, ambient air temperature, ambient air humidity, and atmospheric pressure can all significantly impact the O2 level, which impacts both the thermal efficiency and the pollution emissions from a process heater. Unfortunately, most natural draft process burners are manually controlled on an infrequent basis. This paper shows how changing ambient conditions can considerably impact both CO and NOx emissions if proper adjustments are not made as the ambient conditions change. Data will be presented for a wide range of operating conditions to show how much the CO and NOx emissions can be affected by changes in the ambient conditions for fuel gas fired natural draft process heaters, which are the most common type used in the hydrocarbon and petrochemical industries. Some type of automated burner control, which is virtually non-existent today in this application, is recommended to adjust for the variations in ambient conditions.

Combustor Cooling Wiggle Strip and Geometrical Simplification

The flow fields of a combustor cooling wiggle strip and its corresponding simplified slot with conjugate heat transfer have been studied numerically. The effects of geometrical simplification on the flow fields have been analysed qualitatively and quantitatively. It is found that its effects on the flow velocity and temperature fields are limited to local regions near the cooling element, and are negligible in the far field. However, the simplification shows a considerable effect on the combustor liner temperature near the cooling element, about 8.5% of the average temperature across the cooling element. In short, using the simplified slot to replace the cooling wiggle strip in gas turbine combustor modeling is an acceptable practice if accurate liner temperature prediction is not required.

Application of Diethyl Ether to Reduce Smoke and NOx Emissions Simultaneously With Diesel and Biodiesel Fueled Engines

In this investigation, tests were conducted on a single cylinder DI diesel engine fueled with neat diesel and biodiesel as baseline fuel with addition of 5 to 20% DEE on a volume basis in steps of 5 vol.% as supplementary oxygenated fuel to analyze the simultaneous reduction of smoke and oxides of nitrogen. Some physicochemical properties of test fuels such as heating value, viscosity, specific gravity and distillation profile were also determined in accordance to the ASTM standards. The results obtained from the engine tests have shown a significant reduction in NOX emissions especially for biodiesel and a little decrease in smoke of DEE blends compared with baseline fuels. A global overview of the results has shown that the 5% DEE-Diesel fuel and 15% DEE-Biodiesel blend are the optimal blend based on performance and emission characteristics.

Simulation of Swirl Combustion and NO Formation Using Various Second Order Moment Turbulent Combustion Models and DNS Verification

If the instantaneous chemistry reaction rate is taken as ws = Bρ2Y1Y2 exp(−E/RT) = ρ2Y1Y2K, here K is a contraction for the exponential term. Then, ignoring the three order fluctuation correlation term, the average reaction rate could be ws = ρ2(Y1Y2K + Y1′Y2′K + Y1K′Y2′ + Y2K′Y1′). The authors have simulated jet combustion and swirl combustion using this kind of second order moment (SOM) turbulent combustion model. The predictions are close to experimental data in most regions. In order to improve the SOM turbulent combustion model, the effect of various correlation moments in the simulation of turbulent swirl combustion and NO formation is studied by comparing different SOM turbulence-chemistry models, including the unified second-order moment (USM) model, the model accounting for only the time-averaged reaction-rate coefficient, the model accounting for only the concentration fluctuation and the model accounting for both the time-averaged reaction-rate coefficient and the concentration fluctuation. These models are incorporated into the FLUENT code for a methane-air swirling combustion and NO formation under various swirl numbers. The magnitude of various correlations and their effect on the time-averaged reaction rate are analyzed, and the simulation results are compared with the corresponding measurement results. The results showed that the USM model gives the best agreement with the experimental results and among various correlation moments the correlation of reaction-rate coefficient fluctuation with the concentration fluctuation is most important. Additionally, a direct numerical simulation (DNS) of three-dimensional channel turbulent reacting flows with consideration of buoyancy effect using a spectral method was carried out. The statistical results are shown that K′Y′ are larger than Y1′Y2′.

Process Technology Concerning the Coupled Solid-Liquid Industrial Waste Combustion for the Paper Industry

The paper present the research concerning technical possibilities to tamp the solid industrial waste coming out from an already refurbished paper plant in Adjud, Romania, in order to reduce the overall costs of the necessary landfill deposits and to create a real income by producing energy. An infrared system of a FLIR S65 videocamera (7–14 μm) and double wave length OMEGA OS3750 pyrometer (0.9–1.5 μm) have been used in order to assess the best thermal regime to ignite and to control the burning process of the industrial refuse.

Numerical and Experimental Study of Fire Whirl Generated in 15 × 15 Square Array Fires Placed in Cross Wind

Fire whirls in large city fires and forest fires, which are highly dangerous and destructive, can cause substantial casualties and property damages. It is important to examine under what conditions of weather and geography such merging fires and fire whirls are generated. However, detailed physical characteristics about them are not fully clarified yet. Therefore, we have conducted preliminary studies about merging fires and swirling fires and found that they can enhance the fire spread. If sufficient knowledge can be obtained by relevant experiments and numerical computations, it may be possible to mitigate the damages due to merged fires and fire whirls. The objective of this study is to investigate the swirling conditions of fires in square arrays, applying wind at one corner, in laboratory experiments and also by CFD numerical simulations. Varying the inter-fire distance, heat release rate and mass flow rate by a wind fan, ‘swirling’ or ‘non-swirling’ in the array were judged. It has been found that the fire whirl generation is highly affected by the inter-fire distance in the array, the total heat release rate and also the mass flow rate by a fan. We obtained the conditions of swirling fire generation in 15 × 15 square array for (1) the ratio between the upward mass flow rate vs. applied mass flow rate in the upward swirling plume and (2) a non-dimensional relationship between the heat flow rate in the swirling plume and the applied mass flow rate.

Design and Development of an Improved Air Distributor for a Large Coal-Fired Fluidised Bed Combustor

The air distribution system in a fluidised bed combustor is usually required to provide a reasonably uniform distribution of combustion air over the cross-sectional area of the entire bed. Various designs of distributor have been employed and one of the simplest and cheapest constructions is the so-called sparge pipe system, in which an array of horizontal pipes is fitted near the base of the bed. Combustion air is then supplied to one end of each pipe and enters the bed through a series of downward facing holes positioned along the pipe length. This paper describes the re-design and subsequent modification of an existing sparge pipe distributor for a large coal fired fluidised bed combustor which produced hot exhaust gases for drying of pressed sugar beet pulp. The air flow out of the holes in the existing pipes varied by a factor of approximately 3.8:1 along the length and moreover the overall flow was limited by the high pressure drop within the system. As a result the thermal output of the combustor cannot always meet the demands of the drying process. Excessive erosion and wear of the walls of the pipes near some of the holes can also be a problem. A computational fluid dynamics (CFD) study was undertaken of the flow characteristics of different designs of sparge pipe and the results validated by flow and pressure measurements on full scale laboratory models. The flow distribution was substantially improved and the overall flow rate increased by approximately 7% by varying the hole diameters and spacings between adjacent holes. In addition much greater increases in predicted overall flow rates can be achieved by reducing the thickness of the pipe wall (whilst maintaining a constant outer diameter) although this may reduce the operating life of the pipe because of erosion and excessive wear. Erosion of the outside of the pipes was studied in near ambient temperature fluidised beds using multiple thin layers of different coloured paints on the outside of the pipes to assess the wear patterns. These patterns were found to be similar to those observed on actual sparge pipes at the end of an operating campaign. Quantitative measurements of the rate of wear of the paint layers indicated that pipe wall erosion can be substantially reduced by reducing the angle of inclination of the downward facing holes in the pipes.

Post-Flashover Compartment Fire for Different Fire Ventilation Settings in a Medium-Sized Residential Room

A number of fire ventilation scenarios were investigated in order to identify the proper ventilation scheme for conducting design fire tests in a medium-sized residential room of a size of 4.2 m long, 3.8 m wide and 2.4 m high. The ventilation schemes were based on using a window, door, or both with different sizes. The fuel package that was used in all scenarios consisted of a mock-up sofa made of polyurethane foam and two wood cribs underneath it. The selection of this fuel package is supported by fire statistics that many fatal residential fires begin with an item of upholstered furniture. The CFD technique was used to conduct the numerical simulations for eleven ventilation scenarios using the Fire Dynamics Simulator (FDS) version 5. The effect of window and door sizes, and fire load location on the heat release rate, burning rate, temperature during the period of fully-developed fire (post-flashover), and the onset of post-flashover and its duration were investigated.

Characterization of Piezoelectric Materials for Thermoacoustic Power Transduction

In this work an experimental study of the performance of piezoelectric transducers for power production from a small-scale thermoacoustic engine is presented. Four piezoelectric samples are identified and characterized. These samples are tested on a variable acoustic driver and electrical power produced is measured. Finally, the samples are tested on four experimental thermoacoustic engines to verify the results from the acoustic setup. The maximum power produced is 177 μW from a closed thermoacoustic engine coupled to a 15mm PZT disk.