Chimney Design Research Articles

Field comparative analysis of roof solar chimney design on indoor conditions

SYNOPSIS This paper reports on an experimental investigation of the effect of roof solar chimney design on indoor temperature and induced air change. Five lab-scale houses with different roof configurations were designed and tested. The roof and walls were made from CPAC monier concrete boards. The ceiling was made from gypsum board. The volume of each house was about 1.5 m3. Three roofs were designed to act as a solar chimney whereas two houses with a flat gypsum ceiling served as references (one of them included 1 cm fibreglass insulation) so that no ventilation occurred. In addition, all the houses included two closed-windows located on the northern and southern sides. The three ventilated houses have a rectangular opening located below the northern window through which ambient air is admitted. Experimental results showed that the three solar chimney vented roofs could induce an airflow of 36 m3/h approximately. The corresponding air change is about 24. Indoor temperature stratification varied depending on roof design. The model without a ceiling yielded a higher indoor air temperature than the other two models. The best roof configuration was that designed like a roof solar collector with a centred opening on the flat ceiling. Due to the solar chimney insulating efficiency combined with the induced air change, the indoor conditions, expressed in terms of temperature and air quality, are better than those of the house equipped with fibreglass. It is therefore demonstrated that roof solar chimney ventilation can be used for both reducing the cooling load in the house and providing agreeable indoor air conditions.

Design and measured performance of a solar chimney for natural-circulation solar-energy dryers

The design and construction of a solar chimney which was undertaken as part of a study on natural-circulation solar-energy dryers is reported. The experimental solar chimney consists of a 5.3 m high and 1.64 m diameter cylindrical polyethylene-clad vertical chamber, supported structurally by a steel framework and draped internally with a selectively absorbing surface. The performance of the chimney which was monitored extensively with and without the selective surface in place (to study the effectiveness of this design option) is also reported.

Semi-explicit optimal frequency design of chimneys with geometrical constraints

The purposes of this paper are to develop a new finite-element-based optimal design method for chimneys under a fundamental natural frequency constraint and geometrical constraints (minimum stiffness constraints) and to apply this method to practical chimney design. The chimney is modeled by an FEM system and the bending stiffness distribution is approximated by a piecewise-linear function. A cubic displacement function is utilized in the FEM system. The displacement function is then determined so that the optimality condition described at every point would be satisfied only at the element ends. It is shown that the optimal bending stiffness in the interval with stiffness greater than the given lower bound and the lowest-mode displacements in the interval with the lower-bound stiffness can be obtained semi-explicitly from a set of simultaneous linear equations which is rearranged from a set of governing equations of the lowest eigenvibration. In order to identify the elements with lower-bound stiffnesses, a procedure based on inverse mapping is utilized. Several numerical examples are presented in order to demonstrate the validity and efficiency of this method.

Técnicas actuales para el proyecto y la construcción de las grandes chimeneas industriales

This work intends to make known the deep change met within the design of great-height industrial chimneys. The main characteristics of this kind of work are described, as well as the project with the informatic means used in structural, thermodynamic and smoke dispersion calculations for the optimal design of an industrial chimney.

The seismic design of an industrial chimney with rocking base

An industrial reinforced concrete chimney, of cruciform cross-section and thirty-five metres tall, has been designed and built with the high degree of seismic protection afforded by allowing the base to rock during large earthquakes. As a precaution a pair of purpose-made yielding steel dampers have been installed to assist in the control of the most violent response that might occur.
 This paper discusses the advantages in the adoption of this revolutionary design and describes the hand dynamic analysis carried out during the design process. Subsequent time-history computer analysis carried out to confirm the design method is reported on.

A new look at chimney design

AbstractMaximum concentration formulas make it possible to limit ground‐level concentrations of pollutants.

Prediction of multilayer chimney liner temperatures under unsteady state conditions

A mathematical model is presented which may be used to predict the temperature at any point in a multilayer chimney under the unsteady state conditions encountered with variable inlet temperature and mass flow rate of the chimney gases, and variable ambient temperature. The model satisfactorily predicts the temperatures measured in a three-layer experimental chimney over both the heating and cooling periods of operation. In particular, the model correctly determines the period of time for which any portion of the inner chimney liner is below the acid and water dewpoint temperatures of the chimney gases. By ensuring that this time is minimized by modifications in domestic chimney design and boiler operating conditions, the tendency for acid and water condensation and the attendant chimney corrosion can be substantially reduced.

A new lining for Drax main chimney

The unique chimney design for Drax power station resulted in problems with conventional linings. Low exit flue gas temperatures made it necessary for the chimney flues to be protected from deposited acid attack. A cheap plastic material was initially used to protect the flues, but it failed during precommissioning tests. An alternative protection had to be found in the short period before the chimney became operational. N.E. Region Scientific Services Department together with a manufacturer have developed a new fluoroelastomer plastic lining. The new lining has been installed in two of the flues in the Drax chimney and its performance is being monitored. Life expectancy predictions have been made, based on theoretical treatments of experimental data.

Approximate Fundamental Frequencies for Chimneys

Chimneys are shell structures that are used for discharging gaseous effluents from factories or power plants. When designing a chimney, obtaining the fundamental frequency or period is necessary to be able to determine: (1) lateral forces due to earthquake; and (2) the critical wind velocity that would cause resonant vibrations, due to the shedding of the Karman Vortex. Determining the natural frequencies and performing the dynamic analysis of chimneys has become easier using computers. When performing the preliminary chimney design, engineers require a rapid means for obtaining a reasonably accurate fundamental frequency of a chimney to permit necessary modifications to develop the best design. For this reason, approximate formulas for fundamental frequencies are indispensable for practicing engineers. This note considers unguyed and unlined chimneys (or chimneys with self-supported independent lining). Several commonly used approximate formulas for computed fundamental frequencies are given. Frequencies for chimneys with practical ranges of dimension variables were obtained by computer using Newmark's method. Computer results were compared with those obtained by the existing formulas. From these studies, new approximate formulas that fit the computer results better than the existing formulas are proposed.

Further measurements around modern power stations—I–III: I—Observed ground level concentrations of sulphur dioxide

Continuous measurements of sulphur dioxide were made around West Burton Power Station from its commissioning in 1966 to operation at full 2000 MW load in 1969. Short and long-term ground-level concentrations deriving from the power station in a variety of atmospheric conditions are reported. Comparisons are made with sulphur dioxide values from the nearby 1000 MW power station at High Marnham. It is concluded that the single and combined effects of the two power stations are small, typically only 10 per cent of the background level over a season. Furthermore, the contribution from West Burton is a little less than that from High Marnham, despite the increase in fuel burnt, indicating the effectiveness of the tall chimney design. In all circumstances the observed concentrations and their durations (with both power stations in operation) are less than those which have been observed to harm crops.

Chimney Design for Two Layers of Reinforcement and Concentrated Corbel Moments

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Discussion of “Concrete Chimney Design, Construction and Operation”

Discussion of “Concrete Chimney Design, Construction and Operation”

Concrete Chimney Design, Construction and Operation

Several conclusions are drawn for improving the life and reliability of reinforced concrete chimneys for coal-burning electric generating plants from the experiences of one electric utility over a period of 46 yr. The effects of sulphuric acid attack, abrasion, temperature stresses and weathering are outlined and methods are suggested to reduce or eliminate these effects by special precautions in design and construction. The need for adequate design and good workmanship in construction is stressed in order to obtain a good quality reinforced concrete chimney.

Economics, engineering and air pollution in the design of large chimneys.

A discussion of the methods used to determine the most economic design of chimney for a new thermal power station or large industrial plant is presented, with the objective that ground level concentration of pollutants will be kept at a minimum. Attention is paid to the geography and climatology of the site, with special reference to the frequency and height of inversions and the prevailing wind direction and speed. A method is illustrated in using a large thermal power station as an example. The maximum sulfur dioxide concentrations at ground level are computed for several chimney heights and gas exit velocities. The values of these sulfur dioxide concentrations, the capital cost of the chimney, the pumping costs, and the gas pressures within the chimney are considered in selecting a suitable chimney height and a gas exit velocity which will meet most economically the stated objective. The paper deals primarily with chimneys for industrial or power boiler plant of maximum continuous rating greater than 4...

ECONOMICS, ENGINEERING AND AIR POLLUTION IN THE DESIGN OF LARGE CHIMNEYS.

A discussion of the methods used to determine the most economic design of chimney for a new thermal power station or large industrial plant is presented, with the objective that ground level concentration of pollutants will be kept at a minimum. Attention is paid to the geography and climatology of the site, with special reference to the frequency and height of inversions and the prevailing wind direction and speed. A method is illustrated in using a large thermal power station as an example. The maximum sulfur dioxide concentrations at ground level are computed for several chimney heights and gas exit velocities. The values of these sulfur dioxide concentrations, the capital cost of the chimney, the pumping costs, and the gas pressures within the chimney are considered in selecting a suitable chimney height and a gas exit velocity which will meet most economically the stated objective. The paper deals primarily with chimneys for industrial or power boiler plant of maximum continuous rating greater than 4...

Role of Chimney Design in dispersion of Waste Gases

Role of Chimney Design in dispersion of Waste Gases