Tag:calculation method

№9|2016

PIPELINE SYSTEMS

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UDC 628.144:532.542:691.175

Averkeyev I. A., Gimazieva D. R.

Analysis of methods of hydraulic calculation of pressure pipelines  made of polymer materials

Summary

The analysis of the most pressing for today methods of hydraulic calculations used in domestic design of pressure pipeline systems made of polymer materials was carried out. The methods of hydraulic calculation of pressure pipes were considered on the basis of: pipe friction number formula for hydraulically smooth pipes suggested by F. A. Shevelev; Kolbruk formula (widely used overseas); formula suggested by A. Ia. Dobromyslov. The analysis of the methods was carried out in relation to the applicability and validity of the results of the hydraulic calculations of pressure pipelines. The aim of the analysis was to assist the designer in choosing the most comfortable method of hydraulic calculations of pressure pipes made of polymer materials.

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№3|2019

WASTEWATER TREATMENT

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UDC 628.356.5

Kevbrina M. V., KOZLOV M. N., Dorofeev A. G.

Secondary settlers: comparison of the calculation methods in designing and analysis of the parameters of efficient operation of the facilities

Summary

The results of the comparison of methods of calculating secondary settlers through the example of a model wastewater treatment plant (domestic method according to SNiP 2.04.03-85, German method according to Germany Standard ATV-DVWK-A131E, American method based on mass flow theory) are presented. It is shown that the surface area of settlers calculated according to Standard ATV has higher values compared to the calculations according to SNiP 2.04.03-85 and American method. The values of the surface area of settling tanks calculated according to SNiP 2.04.03-85 and American method are very close. At the same time the SNiP method is much simpler and requires much less initial parameters than the American method. For the domestic practice of operating secondary settlers it is proposed to introduce a new parameter – «dry matter loading on the settler surface» taken from the mass flow theory. This indicator indicates how much dry matter of the mixed liquor from aeration tanks enters per unit surface of secondary settlers per hour and corresponds to the incoming mass flow. By varying the dry matter loading on the surface of secondary settlers it is possible to provide for the standard suspended solids concentration in effluent. Through the example of the operating 54 m diameter settlers the dependence of the clarification efficiency on this parameter is shown.

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№6|2017

SEWERAGE NETWORKS

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UDC 628.21/.25

Vasilyev V. M., Malkov A. V., Verbitskii V. G.

Method of calculating gas volume and its travel direction in a sewer

Summary

In the process of operating deep sewers some problems arise such as corrosion of reinforced concrete structures of the sewerage network, saturation of the gas phase of the underground space with corrosive toxic substances, accidental emissions of these gases from the network into the atmosphere. Solving these problems is possible by arranging air exchange between the sewerage network and atmosphere. The available methods of calculating the amount of gas travelling in the sewerage network do not take into account the gas density, dynamic viscosity and other parameters that depend on the chemical composition of the gas phase. The lack of the recommendations does not allow estimating the network ventilation in relation to providing the required gas exchange rate. Consequently determining, estimating and substantiating the required capacity of the ventilation equipment are not possible. Possible flow redistribution is not considered either; and, hence, adjusting the gas exchange systems to the definite network parameters is not possible. A method of calculating gas amount and flow direction induced by fluid entraining capacity and natural draft with account of the physical and hydraulic parameters of wastewater and gas, network design features, daylight surface temperature is presented. The method provides for making calculations at the design stage with account of retrofitting ventilation units, filters and vent pipes. The following parameters are determined: the amount and direction of gas flow in the network, gas exchange rate, anticipated background concentration of corrosive gases at the preset gas exchange rate, network corrosion rate, overhaul period.

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№6|2020

КАНАЛИЗАЦИОННЫЕ СЕТИ

DOI 10.35776/MNP.2020.06.06
УДК 628.218::628.334.6

Гудков А. Г.

Расчетный метод определения объема регулирующих резервуаров на сетях отведения поверхностного стока (в порядке обсуждения)

Аннотация

Целью работы является дополнение и уточнение методик, приведенных в действующей нормативно-методической базе, для инженерного расчета схем регулирования расходов в сетях дождевого водоотведения. Методом математического моделирования с применением системы компьютерной алгебры проанализированы три схемы регулирования, включающие емкости, насосы и разделительные камеры. Предложена универсальная расчетная формула определения объема регулирующего резервуара в схеме регулирования с опорожнением емкости насосами для всех типов разделительных камер. Установлены зависимости и приведены графики, показывающие влияние на величину объема резервуара коэффициента, который учитывает непостоянство расхода, отводимого разделительной камерой в коллектор. Для схемы регулирования без насоса и разделительной камеры подобрана степенная аппроксимирующая функция, позволяющая проводить расчет величины объема с приемлемой точностью, без численного интегрирования. Для двух схем регулирования с опорожнением самотеком предложены новые формулы определения объема регулирующего резервуара в широких диапазонах коэффициентов регулирования и параметров дождей. Приведены уточненные таблицы, упрощающие инженерные расчеты регулирующих резервуаров. Предложенные в работе формулы и таблицы позволяют рассчитывать емкость резервуаров для всех рекомендуемых схем регулирования расходов.

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№9|2017

PIPELINE SYSTEMS

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UDC 628.144:532.542

Prodous O. A., Vasil'eva M. A.

Simplified form of the normative dependence for hydraulic calculation  of pipelines made of polymer materials (to be discussed)

Summary

Hydraulic calculation of pipelines (pipes) made of polymeric materials is regulated by the acting regulatory documents (SP 40-102-2000). In the aggregate a method (sequence) of hydraulic calculation of pipelines made of polymeric materials with the use of a simplified form of the normative dependence for determining hydraulic resistance coefficient  is proposed. The calculation method is of practical interest because it is confined to the determination of three values included into the normative calculation dependence for the subsequent determination of head losses along the pipeline length. The hydraulic calculation method includes new parameters: hydraulic potential of a pipeline, effective fluid flow rate, effective roughness of the inside pipe surface, effective pipe diameter. These parameters and the Calculation Method have been included into the 3rd edition of the complemented material of Reference book «Tables for hydraulic calculation of pressure polyethylene pipes» (2017). The simplified form of the normative dependence and the method of making hydraulic calculations of pipelines made of polymeric materials can be considered to be included into the revised version of SP 40102-2000.

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№5|2016

NETWORK RELIABILITY

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UDC 628.14:62-192

Yermolin Yu. A., Alekseev M. I.

Consideration of object ageing in estimating its reliability

Summary

The issues related to the estimation of reliability of nonstationary (ageing) objects that are characterized by increasing failure rate with time are discussed. The lack of methods that could be used in engineering evaluation of the reliability of these objects is stated. The method is suggested that consists in nominal replacing the nonstationary object with fictive stationary one with failure rate constant value that is selected basing on several additional considerations. The relationships readily usable in practice and expressing the reliability index of the fictive objects through the parameters of the ageing characteristics of the actual nonstationary objects were obtained.

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