Hydraulic calculation of group water intakes on underground wells equipped with pumps with variable speed drives

Summary

The use of variable speed drives at group water intakes on underground sources in water supply systems is aimed at saving electricity, ensuring efficient operation modes, improving the management engineering; however, without sufficient justification the desired result is not always effected. One of the reasons is the lack of calculation using an effective mathematical model that describes the movement of water in aquifers, wells, lift pipes and gathering mains, taking into account all the existing limitations, including the mode parameters while using variable speed drives in some or in all submersible pumps. The model is submitted in the form of an optimization task where the target function is the total power input of all the operating submersible pumps. The proposed optimization model provides for describing the modes of the group water intakes operating from the intake external boundary to the tanks. All the limitations of the optimization task can be divided into three non-overlapping groups as follows: balance, technologic, and performance ones. Having calculated the electricity consumption for all significant modes during the year and compared them with the costs at the existing modes without variable speed drives, we can make a reasonable conclusion about the applicability of a variable speed drive in one or more submersible pumps. The proposed model provides for arranging both efficient and technologically allowable operating modes.

Key words

frequency converter , water well , aquifer , submersible pump , hydraulic head , flow distribution task , optimization task , energy input , group water intake

DOI 10.35776/MNP.2019.10.04
УДК 614.844

Yepifanov S. P., Zorkaltsev V. I., Baranchikova N. I., Korel’stein L. B.

Hydraulic calculation of automatic firefighting systems
combined with internal fire water pipeline system

Summary

In recent decades the construction of large buildings has risen sharply: shopping and entertainment centers, multifunctional high-rise buildings for residential and public purposes with underground parking lots, storage facilities for the storage of combustible materials. During construction finishing materials are often used that emit toxic substances if ignition occurs. Fires can result in fatalities and substantial material losses. For the fire safety of buildings and structures the use of firefighting water supply – both outdoor and internal is most effective. Due to the inability to provide for outdoor firefighting of a large part of the premises of the upper floors of high-rise buildings, the effectiveness and reliability of internal firefighting systems is of particular importance. Water consumption for fire water supply can be 200 l/s or more. To supply water in such a volume to the fire points, effective internal fire water supply systems are required: automatic firefighting systems (sprinkler and deluge), internal fire water pipelines, deluge water curtains. Combined internal firefighting systems include automatic firefighting installations and internal firefighting water pipeline. The method of hydraulic calculation of each of these systems is available in the regulatory and specialized literature. However, in the process of hydraulic calculations of combined (integrated) firefighting water supply systems, their essential features should be taken into account. In this regard, a mathematical model of flow distribution in automatic firefighting systems combined with an internal fire water pipeline system is considered. The technique of hydraulic calculation of arbitrary combined firefighting water supply systems is given. The proposed model allows you to get an actual value of water abstraction through nozzles (sprayers) and hand control branch pipes.

Key words

pressure , head , hydraulic design , water curtain , automatic firefighting installations , internal fire water pipeline , flow distribution task , variable abstraction

UDC 628.1/.2:621.65

Yepifanov S. P., Baranchikova N. I., Kurtin A. V.

Mathematical modeling of the joint operation of pumping units including frequency regulated ones

Summary

The use of pumping units with variable speed drives in order to save energy and provide for effective operating modes in water supply and sanitation systems, sometimes without sufficient justification, does not always furnish the desired result. One of the reasons is the lack of a simple mathematical model describing the flow distribution in the process pipelines of pumping stations with account of all the limitations of the operating mode parameters while using variable speed drives in some or all pumping units. The flow distribution task itself should be represented in the form of an optimization problem where the objective function can be the total energy input of all the operating pumping units. Such an optimization model provides for describing the operating modes of both paralleled and compound pumps. Once the electricity costs for all significant modes throughout the year have been determined and compared with the existing modes without the use of variable speed drives, drawing a reasonable conclusion about the applicability of variable speed drives in one or several pumping units becomes possible. The proposed model provides for arranging both effective and technologically acceptable modes. Based on the obtained results of calculating the optimization task for several modes, it is possible to construct approximating functions of the total flow of the pumping station from the head losses in throttling devices and use them in case of the flow meter lack or failure.

Key words

pressure , frequency converter , hydraulic head , centrifugal pump , pumping unit , flow distribution task , optimization task , energy input , parallel and serial operation of pumps

DOI 10.35776/VST.2022.02.07
UDC 628.356

Sukharev Mikhail, Baranchikova N. I., Yepifanov S. P., Korel’stein L. B.

Calculation of pneumatic aeration systems in aeration tanks

Summary

The pneumatic aeration system of the aeration tank at the wastewater treatment facilities is considered. Prime costs of electricity at the treatment facilities go towards ensuring the operation of the aeration system, for which reason the problem of the optimal air distribution over all the operational zones is raised. At the same time, either the lack of air, even at some treatment stages, or its excess leads to a decrease in the treatment efficiency. Providing for the controlled air supply only with the use of measuring instruments is quite expensive; therefore, it is proposed to use a mathematical model for aerodynamic calculation of an aeration system with non-fixed air supply through aerators. Based on the results of the aerodynamic calculation, the adaptive control of air distribution in the aeration system with a change in the flow and quality of incoming wastewater, pressure-flow characteristics of aerators, pressure, temperature and humidity of the outside air can be provided. An example of the aerodynamic calculation of a pneumatic aeration system is given.

Key words

air blower unit , pneumatic aeration system , flow distribution task , wastewater treatment facilities , fine-bubble aeration , aerodynamic calculation

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