Tall Chimneys Research Articles

Numerical investigation on the characteristics of dynamic response and damage of a RC tall chimney considering vertical ground motions

Although seismic risk assessment models for structures have become more sophisticated, they have typically disregarded the effects of vertical ground motions (VGMs). Nevertheless, this trend is gradually shifting due to recent recordings and field observations that have demonstrated the potentially destructive effects of high VGMs.In this paper, a nonlinear finite element (FE) model of a 234 m reinforced concrete (RC) chimney is developed, with a focus on investigating its dynamic response and damage characteristics under the effect of VGMs. The results are compared with the case of a combination of horizontal and vertical ground motions (HVGMs). First, a time history analysis (THA) is performed under various VGMs input conditions. The findings reveal that the vertical seismic force increases with the intensity of ground motion. However, the distribution of the seismic force remains unchanged, with the maximum vertical seismic force occurring at 85% of the chimney height. Then, the seismic response of the chimney under HVGMs input conditions is examine, revealing that the maximum vertical seismic force increased by 4%–6%, but its distribution does not change significantly. Furthermore, the effect of the additional mass of the flue is considered, resulting in a significant increase in the vertical seismic force at the suspension points, leading to a change in its distribution. An abrupt increase of about 40% at 1/3 height and an increase of about 45% in the horizontal displacement at the top are observed. The paper also highlights the potential stress concentration and resultants cracks or damage caused by the opening of the chimney barrel.

Vertical limit reduction of chimney in solar power plant

The practical feasibility to install solar updraft tower (SUT) for power production require huge capital investment and difficulties in installing tall giant chimney structure. The chimney is the most expensive element of SUT and typically covers one-fourth of the total SUT cost. Previous finding has shown that a divergent chimney shows significant increase in power output than a conventional design for the same height. This paper deals with the unexplored scientific question: for how much height of divergent chimney can be dispensed with for the same or higher performance of a conventional design? Using an experimentally validated numerical model, we systematically investigated height reduction of chimney (and hence substantial cost) of a high performing divergent chimney whose power output is identical with a long unstable costly conventional cylindrical chimney. The conventional cylindrical design was chosen as the conventional SUT prototype installed at Manzanares, Spain in the year 1980. Results show that it is possible to reduce the vertical limit by about 80% of the height of conventional cylindrical chimney. Further, the cost analysis estimated for each SUT designs and the optimum divergent chimney SUT holds payback period 40% less than the conventional SUT. The proposed designs would be useful for floating chimney as well made of fabric material with light density air filled to keep short chimney height upright vertically to resolve the instability issues with the conventional tall chimney structure during high wind speed environmental conditions The present investigation would assist scientific community to develop more advance clean energy-based power generation systems to achieve net-zero carbon emissions targets.

Effective tuned mass damper system for RC tall chimney dynamic wind response control

Tall chimneys have become necessary due to growing industries and changing environmental norms. Chimneys are tall and slender structures and thus they are sensitive towards wind loads. Thus, it becomes necessary to analyze their performance along both the direction i.e. along the wind and across the wind accurately, and to improve their performance by providing suitable measures. Now a days, Tuned Mass Dampers (TMDs) are provided to improve the performance of structures against dynamic loadings However, there are very few reported studies on the effect of TMDs on wind response control of tall chimneys. Hence, it is important to paper the use of different TMD systems and their performance in chimneys. Two RC chimneys of height of 200 m and 220 m of varying thickness are considered for dynamic wind paper using CFD in ANSYS. Modal response of chimney without and with TMD are also studied. The spring mass analogy is used for the connection of chimney and Tuned Mass Dampers. Gust Factor Method as per IS 875 (III) 2015 and IS 4992-1992, for along and across wind load calculation has been studied. Excel Programme file also prepared for the analysis of wind loads using IS codes. Three TMD systems are considered viz. Single Tuned Mass Damper system (s-TMD) and Multiple Tuned Mass Damper system (m-TMD-1 and m-TMD-2).The analysis results of TMD system are compared with the results of without TMD system. The results are compared on the basis of peak displacements of chimney. It has been found that Multiple TMD systems are more effective than Single TMD system. The reduction in deflection of about 25–30% is observed for m-TMD systems.

Uplift Load Carrying Capacity of Cylindrical and Belled Pile in Cohesive soil Bed

Foundation of some structures like transmission towers, mooring systems for ocean surface or submerged platforms, tall chimneys, jetty structures etc. are subjected to uplift loads. Literature reflects that scholars have conducted pull out field prototype and model test and failure pattern of soil is studied for belled piles in loess soil and cohesionless soil. In this research work, the authors have carried out 36 tests on single pile and pile groups and uplift load carrying capacity is obtained by experimental investigation of single pile, triangular pattern (2x1) and square pattern (2x2) using the model piles of cylindrical and belled shaped in cohesive soil of soft consistency. The piles are having 20 mm shaft diameter and varying L/d ratio of 6, 8,10,15,18 and 20 for both cylindrical pile and belled pile. Belled portion is cast in belled pile with an angle of 70° with horizontal and having base diameter of 60 mm and height 55 mm. Spacing between two piles in various pile group was kept three times the piles shaft diameter (3d) in all experiments. Based on the experimental results as the L/d ratio increases uplift load carrying capacity increases. Uplift load carrying capacity of single pile, triangular pile group and square pile group of belled pile is 410%, 280% and 240% more than cylindrical piles. Uplift load carrying capacity of triangular pile group and square pile group increases by 182% and 273% for cylindrical pile and 104% and 141% for belled pile in comparison with single pile. Failure pattern of soil is obtained from experiments performed on belled pile and by using this failure pattern, theoretical uplift load carrying of belled pile is obtained.Uplift load carrying capacity.

Equivalent Static Wind Load for Structures with Inerter-Based Vibration Absorbers

Equivalent Static Wind Loads (ESWL) are desired in structural design to consider peak dynamic wind effects. Conventional ESWLs are for structures without control. For flexible structures with vibration control devices, the investigation of ESWL is required. Inerter-based Vibration Absorbers (IVAs), due to the light weight and high performance, gained much research attention recently. This paper established a generic analytical framework of ESWL for structures with IVAs. The analytical optimal design formulas for IVAs with different configurations and installation locations are provided. Subsequently, the solutions to uncontrolled and controlled wind-induced responses are derived based on the filter approach. Finally, the ESWL for controlled structures are presented with a gust response factor approach. The ESWL estimation for a tall chimney controlled by IVAs is illustrated, and the results revealed a significant ESWL reduction effect of the IVAs, particularly for the cross-wind vortex resonance. In the presented framework, the conventional uncontrolled ESWL can be converted to the controlled one with a control ratio. The closed form solution of the control ratio is provided, which enables a quick estimation of ESWL for controlled structures particularly in the preliminary design stage. The presented approach has the potential to be extended to more complex structures and vibration control devices.

The main investigations of a novel solar thermal application known as SCPP are summarized in this paper. It is a method of producing electricity from solar energy that relies on the fact that air rises when it is heated. An adequate position within a tall chimney can be utilized to position a turbine to turn it, creating an updraft that

Control issues come from the output voltage of PV installations and systems operating in a range of irradiance and temperature. By using a DC converter, such systems are able to maintain a constant output voltage despite fluctuations in the generated voltage and load. The design of a maximum power point tracking (MPPT) on DC converter controller is presented in this article for a system. Fractional Order-Proportional Integral Derivative (FO-PID) and Parallel Distributed Compensation-Proportional Integral Derivative (PDC-PID) controllers have been implemented to the system converter as a proposed control approach. Particle Swarm Optimization (PSO) is used as optimization technique for determining the optimal parameters of (FO-PID) and (PDC-PID) controllers for tracking the output voltage from trained Adaptive Neuro Fuzzy Inference System (ANFIS) that is corresponding to maximum power generated from (PV) module. The PV system with the dynamic load is modeled and simulated by using the MATLAB/Simulink environment. The system performance is displayed in the form of a family of curves under different operating conditions.

Solar Chimney Power Plants: A Mini Review

The main investigations of a novel solar thermal application known as SCPP are summarized in this paper. It is a method of producing electricity from solar energy that relies on the fact that air rises when it is heated. An adequate position within a tall chimney can be utilized to position a turbine to turn it, creating an updraft that can be used to generate power. This system's specifications, design, construction, and use are all covered in the paper along with experimental and analytical research related to it. It also emphasizes the development and execution of SCPP programs.

Natural convection compound heat transfer enhancement by discrete rings and the chimney effect in a vertical cylinder

Natural convection is an indispensable heat transfer process considered in the design of advanced autonomous nuclear reactors. The renaissance of inherently safe micro nuclear reactors calls for increased post shut down heat rejection rates by passive means. This study numerically investigated heat transfer enhancement in a heated cylinder by discrete rings and the chimney effect. Five equally spaced rings of varying thicknesses and heights were fitted in the heated channel to effect enhancement by flow interruption. The chimney effect was studied by appending adiabatic chimney extensions of different heights, giving rise to extension ratios of 1.5, 1.6, 1.65, and 1.75. Compound enhancement was achieved by attaching chimney extensions to a ringed channel. Nusselt number ratios, mass flow rates, temperature, and velocity profiles were presented. The results showed that compound heat transfer enhancement could increase Nusselt numbers by between 44 and 54% and lower temperatures by over 30% depending on the chimney height. Furthermore, very short chimney heights would be required in the compound setup in comparison to the tall chimneys in the chimney-only cases, for the same target heat transfer rates. The resulting compactness could greatly influence the design of very small reactors and contribute to improvements of other air-cooled passive systems.

City Profile: Manchester, England

City ProfileManchester, England Joshua Allan (bio) Books for Your Table in Chetham’s Reading Room Jennifer Nansubuga Makumbi Manchester Happened Oneworld, 2019 Elizabeth Gaskell Mary Barton Penguin Classics, 1997 W. G. Sebald The Emigrants Trans. Michael Hulse New Directions, 2016 Click for larger view View full resolution “THE CITY CENTRE was at once beautiful and scary. . . . The infrastructure alone— of brick and stone—was forbidding. The skyline—dotted by conical, sharp church steeples and tall chimneys—made him feel trapped. . . . Manchester brought to mind a Christian heaven of arches and arches, spires, steeples, pews and church bells. But why would the British sculpt snarling devils on their walls when they lived in such dark misty environs?” This is how Manchester looks to the outsider, or more specifically to the Ugandan immigrant Abu, the protagonist in the first story in Jennifer Nansubuga Makumbi’s new collection, Manchester Happened. The date is 1950, but it could just as easily be 1800, when church steeples and mill chimneys clogged the smoky skyline like a chessboard midmatch. And it could just as easily be today, when, even though spire and chimney have given way to flat and office block, the city is still renowned for its gloomy atmosphere and the gothic, industrial architecture that confronts visitors at every turn. Despite—or rather, because of—Manchester’s tenebrous reputation, the city has continued to attract writers for centuries. The beginning of Jane Eyre was written on the site where Manchester Metropolitan University now stands. Head north and you’ll find Chetham’s Library, the oldest public library in the English-speaking world, where Marx and Engels wrote The Communist Manifesto. Elizabeth Gaskell wrote her novels in a house on Plymouth Grove—you can still visit it. W. G. Sebald, who came to Manchester to teach, set the final, and most melancholic, part of The Emigrants against the foggy backdrop of “the sprawling mass of Manchester . . . a fire almost suffocated in ash.” My brother lives in a converted mill featured in one of the novel’s black-and-white photographs. If the photo had been taken from the other side, a few decades later, it would have displayed a sign that my brother misread as “burgers” (American cuisine is now ubiquitous in the city). It is in fact a sign for the International Anthony Burgess Foundation, a tribute to the writer who took the opposite trajectory from Sebald by leaving the city as soon as he could. But the “Manchester of frightful slums and hard-head magnates and cotton brokers gorging red meat in chophouses,” “the mother of liberalism and the cradle of the entire industrial system,” never left him. I find myself in a similar position to Burgess, being continually drawn back to Manchester. The city has a staggering literary history, but it is perhaps more dynamic nowadays than it has ever been. Both universities boast renowned creative writing courses, with past and present teachers including Martin Amis, Jeanette Winter-son, Lemn Sissay, and Carol Ann Duffy. In 2017 it was named a unesco city of literature. And as the most linguistically diverse city in western Europe, the city’s status as a cultural wellspring has become indisputable. The “dark misty environs” might remain, but now anyone can feel at home. [End Page 5] Joshua Allan Joshua Allan works for Routledge books in Oxford, England, and writes extensively on the side. He has published in WLT, the Oxford Review of Books, Undercurrent Philosophy, Full Stop, Eunoia Review, and other magazines. Copyright © 2022 World Literature Today and the Board of Regents of the University of Oklahoma

Analysis of tall chimney with piled raft foundation under wind load using ANSYS

Chimneys are the principal structures in any industry that emits pollutants to higher parts of the atmosphere. The geometrical traits of the chimney are so unique that it has slender dimensions and tapering geometry and therefore the analysis and design of chimney and other forms of tower structures should be carried out individually. Nowadays chimney heights have gone up from 100 m to more than 400 m according to the purpose that it serves. These tall chimneys are very sensitive to wind loads. Wind load is one of the most important parameters that affect the response of tall building’s chimneys. When tall chimneys are subjected to wind load, it may undergo lateral deflection. It also leads to the development of radial and tangential moments along with base moments. The dynamic wind effects on chimneys by analytical procedures are intricate and take a great amount of time. To analyze and further improve the response of chimneys, analysis using commercial finite element (FE) software ANSYS is carried out. Chimney with and without providing stiffeners is analyzed using ANSYS and the lateral deflection and bending moment found from the chimney models are compared. This method is more economical and time-saving.

Radial Turbine Design for Solar Chimney Power Plants

Solar chimney power plants (SCPPs) collect air heated over a large area on the ground and exhaust it through a turbine or turbines located near the base of a tall chimney to produce renewable electricity. SCPP design in practice is likely to be specific to the site and of variable size, both of which require a purpose-built turbine. If SCPP turbines cannot be mass produced, unlike wind turbines, for example, they should be as cheap as possible to manufacture as their design changes. It is argued that a radial inflow turbine with blades made from metal sheets, or similar material, is likely to achieve this objective. This turbine type has not previously been considered for SCPPs. This article presents the design of a radial turbine to be placed hypothetically at the bottom of the Manzanares SCPP, the only large prototype to be built. Three-dimensional computational fluid dynamics (CFD) simulations were used to assess the turbine’s performance when installed in the SCPP. Multiple reference frames with the renormalization group k-ε turbulence model, and a discrete ordinates non-gray radiation model were used in the CFD simulations. Three radial turbines were designed and simulated. The largest power output was 77.7 kW at a shaft speed of 15 rpm for a solar radiation of 850 W/m2 which exceeds by more than 40 kW the original axial turbine used in Manzanares. Further, the efficiency of this turbine matches the highest efficiency of competing turbine designs in the literature.

Performance of a TMD to Mitigate Wind-Induced Interference Effects between Two Industrial Chimneys

The present paper studies the performance of a tuned mass damper (TMD) installed in a 183 m tall chimney located at the edge of the wake shed by another chimney. Numerical and experimental results are available. For the simulations, wind action is considered by solving several 2D flow problems on a selected number of horizontal planes, in the transverse direction to the stacks. On such planes, Navier-Stokes equations are solved to estimate the fluid action at different positions of the chimneys and standard interpolation techniques are applied in the vertical direction. An Arbitrary Lagrangian-Eulerian (ALE) approach is used to consider the moving domain, and a fractional-step scheme is used to solve the fluid field. For the structural modelling, chimneys are meshed using 3D beam finite elements. The time integration procedure used for the structural dynamics is based on the standard second order Bossak method. For each period of time, the fluid problem is solved, the aeroelastic analysis is carried out and the geometry of the fluid mesh of each plane is updated according to the structural movements. With this procedure and model updating techniques, the response of the leeward chimney is evaluated for different scenarios, revealing an interesting dependence of the TMD performance on the wind speed and direction.

Tall Chimney Lining Inspection using Structure from motion and drone photography

Recently, in the practical inspection on inner lining of tall chimneys of plants or power stations, the movie captured by 360-degree action camera installed on drone is reviewed by engineer for screening. It reduced man-hours and increased safety than visual inspection using scaffold.

Comparison of international wind codes for across wind response of concrete chimneys

Lift force arises due to the shedding of vortices in the wake of structures. Flexible structures such as the chimney tend to experience aero-elastic phenomenon during the vortex-induced across wind vibration caused due to vortex induced lift forces. While rigorous theoretical analysis including the aero-elastic effect is desired for the validation of the design of the chimney and for performing the reliability analysis, the initial design of the chimney for wind induced forces is routinely performed using code provisions. Almost all the countries have their codes for considering the wind loads on chimneys. For the design of tall chimneys for across wind forces, different codes differ in their approaches and provide different code provisions. The objective of the present paper is to compare seven major international code methods for the design of reinforced concrete chimneys for across wind forces and to present the basis of the formulations of their code provisions. They include the CICIND-2011, ACI 307-08, NBCC, IS 4998:2015, AS/NZ 1170.2:2011, Euro code method-I (EN 1991-1-4) and Euro code method-II (EN 1991-1-4). It is shown that the equivalent static formulas provided by different codes follow either Vickery and Basu method or Ruscheweyh’s method. Further, how different code formulae are derived from these two formulations is shown while comparing different codes. The comparison of different important code provisions is illustrated and evaluated with the help of three numerical example problems.

Investigation on determining uplift capacity and failure mechanism of the pile groups in sand

Foundations of some structures such as transmission towers, mooring systems for ocean surface or submerged platforms, tall chimneys, jetty structures are subjected to uplift loading. In such cases, to increase the uplift resistance of piles, pile foundations like anchored piles, batter piles and micro piles are extensively employed depending on in-situ conditions. This paper deals with the contribution of pile surface to the uplift capacity and the failure mechanism obtained for the pile groups in sand, and the main goal of the study is to investigate the effect of the pile surface roughness on the uplift capacity for different spacing ratios between piles. Therefore, the paper presents some findings of a single pile and pile groups embedded in sand under uplift loading. The variables investigated include the pile surface, pile embedment ratio and the spacing ratio between piles. Experiments were conducted to study foregoing parameters, and three-dimensional analyses were performed using the finite element method to illustrate the failure mechanism of pile groups and the interaction between piles for different spacing ratios between piles. The results show that the finite element simulation results indicate good agreement with the experiment results, and all variables significantly affect the uplift capacity of piles.

Interference effects between two tall chimneys on wind loads and dynamic responses

The wind loads of two chimneys with different distances and incident angles were obtained by pressure measurement tests, and the results were presented as interfering factor (IF) contours. The interference effects on the across-wind loads were significantly greater than those on the along-wind loads. The dynamic responses of the chimney were calculated using the frequency domain method, and the extreme response interfering factors (RIFs) at different reduced wind velocities were obtained. For the extreme along-wind responses, the most unfavorable incident angle (MUIA) was 105°, and the maximal RIF was 1.3. For the extreme across-wind responses, the MUIA was 15° or 30°, and the maximal RIF was 1.9. Moreover, the combined envelope interfering factors (EIFsc), which were the combined maximal RIFs of all reduced wind velocities, were determined by combining the along- and across-wind responses. Because the equivalent static wind loads are determined based on the structure responses, EIFsc can be used as the IFs of the equivalent static wind loads as guide for wind-resistant designs of actual chimneys.

Design of Tall Chimney for Thermal Power Plant

Design of Tall Chimney for Thermal Power Plant

Effect of Lateral Loads and Soil Structure Interface on Structural Performance of RCC Chimney

Chimneys are distinguished requirements for Power generation and other Manufacturing areas which are vital to be constructed vertically to discharge combustion gases and chemical waste gases to the environment. Due to the hasty growth of mechanization and escalating the requirement to control of Air pollution, the construction of tall Chimneys becomes a regular structure in contemporary circumstances. Tall chimney shells generally designed to resist vertical and lateral loads especially due to the effect of Wind and Earthquake. RCC Chimney shell will transfer these vertical and lateral loads to its foundation system. Soil Structure Interaction (SSI) is the response of soil which impacts the behavior of the structure or behavior of the structure which affects on response of soil. Soil Structure Interaction is essential for tall structures which especially resting on soft soil strata. This review work presents a widespread appraisal of the research presented in the area of RCC chimney and communicates most recent enlightenments and improvements happened in the analysis and design. This paper makes an attempt on focusing the modeling features of RCC chimneys which contains analysis, design aspects and several case studies, with the help of various software programs with the effects of lateral loads and soil structure interaction. The present review paper also corresponds to a complete anthology of the research accomplished on RCC chimney and will gives rationalized technical information for the researchers.

Numerical Investigations on Suppression of Aeolian Vibrations on a Tall Chimney Using Helical Strakes

Tall chimneys subjected to hefty wind loads undergo structural failure catastrophically. This paper aims to investigate the across wind oscillations of the structure during wind and the effect of helical strakes in reducing the wind loads that cause vortex-induced vibrations (VIV). A computationally less expensive RANS simulation used for investigation of wind loads on a tall chimney of height 180 m. The air flow is presumed to be predominantly turbulent and incompressible in the flow field. Shear Stress Transport (SST) k-ω turbulence model is used to capture the turbulent characteristics accurately. The response of the structure to wind loads is investigated for the same velocity on a bare chimney and one fitted with helical strakes. The influence of the helical strakes in reducing the VIVs is analyzed in terms of Strouhal number. It has been observed that the use of helical strakes could significantly reduce wind loads and the magnitude of vortex instabilities around the structure. The obtained results are in reasonable agreement with the available experimental works in the literature.

Non-Destructive Testing of Technical Conditions of RC Industrial Tall Chimneys Subjected to High Temperature.

Non-destructive tests of reinforced concrete chimneys, especially high ones, are an important element in assessing their condition, making it possible to forecast their safe life. Industrial chimneys are often exposed to the strong action of acidic substances, They are negatively exposed to the condensation of the flue gases. Condensate affects the inside of the thermal insulation and penetrates the chimney wall from the outside. This is one reason for the corrosion of concrete and reinforcing steel. Wet thermal insulation settles, and drastically reduces its insulating properties. This leads to an increase in temperature in the reinforced concrete chimney wall and creates additional large variations in temperature fields. This consequently causes a large increase in internal forces, which mainly increase tensile and shear stresses. This results in the appearance of additional cracks in the wall. The acid condensate penetrates these cracks, destroying the concrete cover and reinforcement. Thermographic studies are very helpful in monitoring the changes in temperature and consequently, the risk of concrete and reinforcement corrosion. This simple implication between changes in temperature of the chimney wall and increasing inner forces as shown in this article is particularly important when the chimney cannot be switched off due to the nature of the production process. Methods for interpreting the results of thermovision tests are presented to determine the safety and durability of industrial chimneys.