EMPIRICAL DEPENDENCE OF THE HYDRAULIC RESISTANCE OF THE WA-TER LAYER OF THE REGULAR PACKING ON THE RESISTANCE COEFFI-CIENT AND IRRIGATION DENSITY

A criterion equation for the coefficient of hydraulic resistance of a layer of regular packing was ob-tained, and a dependence was obtained that connects the hydraulic resistance of a dry and irrigated packing.

Dynamic Behavior of Liquid Flow Rate from Nozzles in Jet Scrubbers of Pulp Production

It is shown that the modern development of pulp production technology is associated with the development of gas-liquid systems equipment. Such equipment provides the main technological processes of pulp cooking and regeneration of chemical reagents. Furthermore, this equipment, designed to recover chemical reagents and reduce their emissions into the environment, is part of the technological process. The use of scrubbers in pulp production has an advantage over many other industries, since it uses a closed liquor regeneration cycle. Currently, studies of the processes occurring in scrubbers of different types are becoming more numerous and fundamental. This paper is devoted to the development of jet scrubbers. These devices have a number of properties that do not have scrubbers of other types. They do not create resistance to the gas flow in the flue; they have a gravitational property due to ejection. Only jet scrubbers create the necessary conditions for the stability of the gas flow and have a jet effect that allows to significantly increase the efficiency of emissions cleaning. To implement the jet effect and intensify the technological equipment operation it is required to describe transfer processes in jet scrubbers with regard to polydisperse structure of drop flow and features of liquid splitting up into drops by centrifugal-jet nozzles. Scientific works devoted to the problem of realization of the jet effect showed the need to study the dynamics of liquid splitting in centrifugal-jet nozzles, which create a drop-filled jet with a large opening angle. The research purpose is to study the speed of the initial movement of drops in the area immediately after the splitting section of the continuous jet of liquid flowing from the nozzle. A photographic technique with two spark lamps was used for the experiment. At the same time, the distribution of irrigation density was controlled. The results of measuring the distributions of absolute speed of drops and irrigation density were compared with each other and the function of liquid speed distribution in the cross section of the gas-liquid jet of the jet scrubber was determined. Based on the obtained data, a theoretical model was developed to determine the initial speed of drops of centrifugal jet nozzles, an indicator required for the development of new jet scrubbers. The results can be applied to improve the technological processes of pulp production.

Calculation of Hydrodynamic Characteristics of Apparatus with Regular Tubular Packing

Among the apparatuses with a regular arrangement of packing elements creating an in-phase mode of vortex interaction, which ensures high efficiency of the processes, it is interesting to use a standard tubular packing. Such packing allows additional advantages associated with heat supply or extraction directly in the contact zone of the interacting phases, which is very important for conducting some chemisorption processes. The research covers such hydrodynamic regularities as hydraulic resistance during a heat carrier movement in pipes and during external flow around a tubular beam, retained liquid amount and gas content of layer in the external flow around the tubular beam with liquid and gas flows. The research was carried out using an experimental setup with a heat and mass transfer apparatus with regular tubular packing. The medium used during experiments is water-air. The research methodology included standard methods for determining hydraulic resistance and retained liquid amount and visual observation and photographing of gas-liquid flows. The novelty of the research was equations – one for calculating the hydraulic resistance in pipes, taking into account local resistances and pipe roughness. The other ones for determining the pressure losses during the external flow around the tubular beam, the retained liquid amount, and the gas content of the layer, taking into account the vortex interaction of gas and liquid flows. Graphical and calculated dependences of the investigated hydrodynamic characteristics were obtained as a result of the conducted research of the hydraulic resistance during the heat carrier movement in the pipes, as well as the hydraulic resistance and the retained liquid amount during the external flow around the tubular beam with a change in the gas velocity and irrigation density. When the heat carrier flows in the pipes, the numerical values of the hydraulic resistance in the transient mode do not exceed 1.5 kPa, in the developed turbulence mode in the range of the Reynolds number from 1·104 to 6·104 DР varies from 1.5 to 53 kPa. With the external flow around the tubular beam, in the developed turbulence mode wg = 4 m/s and L = 25 m3/m2h, the hydraulic resistance is 85 Pa, the retained liquid amount is 4.5·10-3 m. The change in the irrigation density in this mode (developed turbulence) in the L range from 10 to 100 m3/m2h leads to an increase in the hydraulic resistance from 65 to 160 Pa, the retained liquid amount from 2.16·10-3 to 13.6·10-3 m. The calculated dependencies are the basis of the method for calculating the hydrodynamic characteristics of the apparatus with the regular tubular packing, which can be used to calculate industrial devices.

Study of operation of natural draft cooling tower, with its hydraulic load reduced

A survey has been held of a BG-2600 natural draft cooling tower of thermal power plants, in the reduced hydraulic load mode. The technical condition of the reinforced concrete tower, the skeleton frame, the irrigation device, the water distribution system and the air duct windows has been inspected. Defects of the cooling tower structural elements have been identified. These include: horizontal sagging of the irrigation device, considerable gaps between its blocks and their partial destruction, problems with nozzles and structures of air duct windows. The identified defects are attributed to the causes of irregular water and air flows. The degree of irregularity of irrigation density and air flow in the tower has been estimated. Over the cross-section of the tower, a significant standard deviation from the average value or irregularity of irrigation density (30%) and irregularity of air flow (23.5%) has been established. The temperature and cooling curves of the cooling tower have been plotted taking into account irregularities of irrigation density and air flow rate. Normal and defective sections of the cooling tower have been identified based on working characteristics. Standard characteristics of the BG-2600 cooling tower have been plotted based on a nomogram. A comparative analysis of the working and standard characteristics has been held. The degree of influence produced by irregularities in water and air flows on the cooling process has been established. It has been found that the established irregularities in water and air flows result in a decrease in the temperature difference on average by 2°C and a decrease of cooling capacity by 7.3 Mcal/m2∙hr with a hydraulic load of 8840 m3/h. The results indicate a significant impact produced by irregularities of flows on cooling effect. The tasks to eliminate irregularities in distribution of flows as well as to increase the tower cooling efficiency have been formulated.

Statistical Data Collection Methodologies of Irrigated Areas and Their Limitations: A Review

Inconsistencies in the statistical datasets of irrigated areas at the national level could have considerable implications for policies developed for food and water security. Remote sensing can address this issue, however, dubieties of its reliability inhibit its protagonist role. Methods that integrate both remote sensing based and statistical datasets seem expedient, and they are more likely to be acknowledged by the policymakers. Therefore, it is important for scientists to know the basis and limitations of statistical datasets which originate at the country level. Data collection methodologies of irrigated areas were reviewed for seven Asian countries, namely China, India, Pakistan, Bangladesh, Nepal, Indonesia, and Thailand. Factors causing the uncertainties in data, and the limitations of data collection methodologies were highlighted. Also, an irrigation density distribution analysis was conducted to understand the relation of spatial spread pattern of irrigated areas and uncertainty in their statistical records. It was found that irrigated areas statistics are mostly based on the information originating from water user associations and farmers, which is either self-reported or it is collected through interviews during surveys and censuses. The main causes of discrepancy were lack of resources to frequently enumerate the irrigated land, inconsistency in the data collection methodologies, unaccounted secondary crops, illegal and unregulated water use, and bureaucratic and political constraints. Irrigation density distribution analysis showed that the largely scattered irrigated areas might be prone to lack of comprehensive and frequent enumeration. Furthermore, dense irrigation regions might have potentially unrecorded irrigated areas where temporary or supplementary irrigation arrangements are made by the marginal farmers.

Estimation of the distribution of water and air flows in a laboratory cooling tower

A decrease in the efficiency of the tower cooling tower of the TPP was found, especially in the summer. It has been proposed that one of the reasons for the decrease in productivity may be uneven distribution of flows. Experimental studies of the density distribution of irrigation water and air flow of a tower cooling tower have been carried out. The actual operating characteristics of the cooling device are obtained taking into account the uneven flow. Due to the influence of internal and external factors on the performance of the full- scale tower, it was decided to check the performance at its laboratory installation. An experimental analysis of the distribution of irrigation density and air velocity was performed on a laboratory model of a cooling tower. The experimental characteristics of the full-scale tower cooling tower in a laboratory installation were confirmed: the dependence of air speed, temperature drop of water and cooling power on the distribution of irrigation density. Taking into account the uneven flow of water and air is an important task in the design and operation of tower towers. The problem of rational distribution of irrigation density and air flow in a tower cooling tower is formulated.