bbk 000000
UDC 628.12:62-531.3
KARGIN S. A.
Analysis of Electric Power Losses in the Course of Operation of a Group of Pumps Equipped with Adjustable Drive
Summary
Calculations of the power losses in pump units with aggregates operating simultaneously, one of them is adjustable, are presented. The main advantage of a control scheme with one adjustable pump is a relatively low cost of an apparatus part. But additional power losses connected with reduction of rotation frequency of a pump impeller of the adjustable pump in the course of operation of unregulated pumps under conditions of maximum output are unavoidable. Calculations of these losses made with the use of vector diagrams of hydraulic capacity of pumps make it possible to develop a structure of a power efficient pumping unut characterized by acceptable cost of equipment and minimal power expenditures to maintain the preset pressure in a pressure line.
Key words:
pressure , pump unit , frequency of pump impeller rotation , capacity , hydraulic capacity , frequency of feeding voltage , frequency converter
|
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
|
bbk 000000
UDC 628.147.2
Karmazinov F. V., Melnik E. A., Ipatko M. N., Il'in Iu. A., IGNATCHIK V. S., Ignatchik S. Iu.
The method of evaluating the economic efficiency of water supply systems with pumping stations equipped with tanks
Summary
A method of evaluating the economic efficiency of the water supply systems with pumping stations equipped with tanks is presented that provides for optimizing at the design stage water conveying systems in remote areas. These systems are characterized by: low energy efficiency because of the pressure loss during water discharge and low network reliability during bypass operation caused by pressure fluctuation. The method takes into account the specific features of simultaneous operation of two subsystems: pipeline and valving subsystem and booster pumping subsystem. The selection of net discounted flow rate over the life cycle as a uniform optimization criterion for all the subsystems is substantiated. It is stated that the economic and energy efficiency of the investment projects of upgrading water conveying systems is a function of the actual inlet pressure in the supply pipelines and depends on the engineering measures aimed to improve it. These measures include the use of valves for downstream pressure control, mini-hydropower units and auxiliary low head pumping stations. By the example of Parnas booster pumping station in St. Petersburg it is shown that the use of the developed method allows improving the reliability coefficients of the water supply system to P(t) > 0.95 with simultaneous 17% reduction of the net discounted flow rate over the life cycle. In this case depending on the actual inlet water pressure in the supply pipeline the energy consumption of a pumping station is reduced by 22–60%.
Key words
pressure , water supply network , energy efficiency , pumping station , control valve
|
bbk 000000
UDC 628.15:62-531.3.004.18
LEZNOV B. S., Vorobiev S. V.
Assessment of Water Saving When Using the Regulated Electric Drive in Pumping Plants of Water Supply Systems
Summary
Methods of the assessment of water saving developed by specialists of the Yagorba Ltd. and the automation laboratory of the NII VODGEO PC are described. The assessment of water saving when using a regulated drive for various variants of pumping plants operation in the water supply systems can be made with the help of these methods. Results of the calculation are close sufficiently to the results of operational supervision on real objects. This procedure can be used for estimation of reduction of wastewater disposal into the sewerage owing to the reduction of non-productive discharges in a water delivery system. The example of calculation of predicted water saving for a pump installation with one and several units is presented.
Key words
adjustable electric drive , pressure , water supply , pump unit , water supply system , water saving , energy , non-productive discharges of water
|
bbk 000000
UDC 628.144:532.542
Baranchikova N. I., Yepifanov S. P., Zorkaltsev V. I., Kurtin A. V., Obuzdin S. Iu.
Flow distribution in water supply and distribution systems with automatic pressure regulators
Summary
The task of flow distribution in general pipeline systems including the systems of water supply and distribution with automatic pressure regulators is considered. To improve the reliability of the system operation pressure regulators are often installed «downstream» (reducing valves) and «upstream» (tank release valves). Pressure regulators manufactured by Bermad have been installed in the water distribution networks of Irkutsk; that provided for reducing and stabilizing the pressure in some zones. However zones exist that are supplied from several water pipelines with different pressure at the connection points, therefore sometimes complete closing of some regulators occurs (more often with small diameters) or flow reversal is possible, and the water flows through the regulator in the opposite direction. In this case the regulator fails to fulfill its function. Mathematical modeling of such situations is very important because it is them which significantly complicate the operation of the water supply and distribution systems. Mathematical models of automatic «upstream» and «downstream» pressure and pressure drop regulators are suggested with account of their version: normally open or normally closed. The mathematical formulation of the problem of flow distribution in the systems of water supply and distribution with pressure regulators is presented. The critical for the practice task of flow distribution in the pipelines with automatic regulators has been solved for the setting that describes different scenarios of the automatic regulators operation. A simple and efficient method of solving the set task of flow distribution that does not require derivation and has rapid enough convergence is suggested. On the basis of the numerical experiments it is fair to assume that the number of iterations moderately depends on the dimension of the problem (number of nodes and semicircular arcs), considerably depends on spread of hydraulic resistance values and to a lesser extent – node selection.
Key words
pressure , mathematical model , pipeline system , flow distribution , hydraulic head , systems of water supply and distribution
|
bbk 000000
UDC 628.144
Bol'shev K. N., Ivanov Vasilii Alekseevich, Stepanov A. A., Varfolomeev G. R.
Temperature and pressure monitoring system of the water distribution networks of Yakutsk
Summary
The information on the design of the system of monitoring temperature and pressure in the water distribution networks of Yakutsk is presented. In operating the municipal water supply under low temperature conditions continuous water temperature and pressure monitoring in the network is needed to prevent from pipeline freezing and overheating of the pumped water. To this end automated systems of temperature and pressure monitoring in the networks have been developed. To provide for the data remote transfer for the system control Circuit Switched Data (CSD) technology for GSM mobile networks is used. With the help of this technology two GSM modems can establish a communication channel for import of data. For the operation of this system at a remote measuring point a cellular communication signal of the selected operator at the facilities together with continuous power supply shall be available. AIR-10N pressure sensors and TSPU-205-N temperature sensors were used as transmitters with 4–20 mA standardized signal; CPU – computer-process interface modules manufactured by Elemer SPE OJSC were used for subsequent transformation of signal and interface. Exchange of data between the computer and analogue input modules is ensured by MODBUS protocol version. To provide for the system control an information computerized system including a data base with Microsoft SQL Server 2008 Express, a service of terminal polling with the help of Windows service application, and an operator interface was developed. At present the system is operating steadily in the mode of systematic polling. The designed system can provide for collecting data from 200–300 measuring points.
Key words
water supply , monitoring , pressure , pipeline , centralization of control , temperature
|
|
