Today we will figure out how to produce hydraulic calculation heating systems. Indeed, to this day the practice of designing heating systems on a whim is spreading. This is a fundamentally wrong approach: without preliminary calculations, we raise the bar for material consumption, provoke abnormal operating conditions and lose the opportunity to achieve maximum efficiency.

Goals and objectives of hydraulic calculations

From an engineering point of view, a liquid heating system appears to be a rather complex complex, including devices for generating heat, transporting it and releasing it in heated rooms. Ideal operating mode hydraulic system heating is considered to be one in which the coolant absorbs maximum heat from the source and transfers it to the room atmosphere without loss during movement. Of course, such a task seems completely unattainable, but a more thoughtful approach makes it possible to predict the behavior of the system in different conditions and get as close to benchmarks as possible. This is the main goal of designing heating systems, the most important part of which is rightfully considered hydraulic calculation.

Practical goals hydraulic calculation are:

1. Understand at what speed and in what volume the coolant moves in each node of the system.
2. Determine what impact a change in the operating mode of each device has on the entire complex as a whole.
3. Determine what performance and performance characteristics of individual components and devices will be sufficient for the heating system to perform its functions without significantly increasing the cost and providing an unreasonably high margin of reliability.
4. Ultimately, to ensure a strictly dosed distribution of thermal energy across various heating zones and to ensure that this distribution will be maintained with high constancy.

One can say more: without at least basic calculations it is impossible to achieve acceptable stability and durable use equipment. Modeling the operation of a hydraulic system, in fact, is the basis on which all further design development is built.

Types of heating systems

Engineering calculation tasks of this kind are complicated by the high diversity of heating systems, both in terms of scale and configuration. There are several types of heating junctions, each of which has its own laws:

1. Two-pipe dead-end system a is the most common version of the device, well suited for organizing both central and individual heating circuits.

Transfer from thermotechnical calculation to hydraulic is carried out by introducing the concept of mass flow, that is, a certain mass of coolant supplied to each section heating circuit. The mass flow is the ratio of the required thermal power to the product of the specific heat capacity of the coolant and the temperature difference in the supply and return pipelines. Thus, in the sketch heating system mark the key points for which the nominal mass flow is indicated. For convenience, the volumetric flow is determined in parallel, taking into account the density of the coolant used.

G = Q / (c (t 2 - t 1))

• Q - necessary thermal power, W
• c— specific heat coolant, for water accepted 4200 J/(kg °C)
• ΔT = (t 2 - t 1) - temperature difference between supply and return, °C

The logic here is simple: to deliver required amount heat to the radiator, you must first determine the volume or mass of coolant with a given heat capacity passing through the pipeline per unit of time. To do this, it is necessary to determine the speed of movement of the coolant in the circuit, which is equal to the ratio of the volumetric flow to the cross-sectional area of ​​the internal passage of the pipe. If the speed is calculated relative to the mass flow, you need to add the coolant density value to the denominator:

V = G / (ρ f)

• V - coolant movement speed, m/s
• G—coolant flow, kg/s
• ρ is the density of the coolant; for water it can be taken as 1000 kg/m3
• f is the cross-sectional area of ​​the pipe, found by the formula π-·r 2, where r is the internal diameter of the pipe divided by two

Flow and velocity data are necessary to determine the nominal diameter of the interchange pipes, as well as the flow and pressure circulation pumps. Devices forced circulation must create overpressure, allowing to overcome the hydrodynamic resistance of pipes and shut-off and control valves. The greatest difficulty is presented by the hydraulic calculation of systems with natural (gravity) circulation, for which the required excess pressure is calculated based on the speed and degree of volumetric expansion of the heated coolant.

Head and pressure losses

Calculation of parameters using the relationships described above would be sufficient for ideal models. IN real life both the volumetric flow and the coolant velocity will always differ from the calculated ones at different points in the system. The reason for this is hydrodynamic resistance to the movement of the coolant. This is due to a number of factors:

1. The forces of friction of the coolant against the walls of the pipes.
2. Local flow resistance formed by fittings, taps, filters, thermostatic valves and other fittings.
3. The presence of branches of connecting and branch types.
4. Turbulent turbulence at turns, contractions, expansions, etc.

The task of finding the pressure drop and velocity at different areas systems are rightfully considered the most complex; they lie in the field of calculations of hydrodynamic media. So, the friction forces of the fluid about internal surfaces pipes are described logarithmic function, taking into account the roughness of the material and kinematic viscosity. With the calculations of turbulent vortices, everything is even more complicated: the slightest change in the profile and shape of the channel makes each individual situation unique. To facilitate calculations, two reference coefficients are introduced:

1. Kvs- characterizing the throughput of pipes, radiators, separators and other sections close to linear.
2. K ms- determining local resistance in various fittings.

These coefficients are indicated by manufacturers of pipes, valves, taps, and filters for each individual product. Using the coefficients is quite easy: to determine the pressure loss, Kms is multiplied by the ratio of the square of the coolant speed to the double acceleration value free fall:

Δh ms = K ms (V 2 /2g) or Δp ms = K ms (ρV 2 /2)

• Δh ms — pressure loss at local resistances, m
• Δp ms—pressure loss at local resistances, Pa
• K ms - coefficient local resistance
• g—gravitational acceleration, 9.8 m/s 2
• ρ - coolant density, for water 1000 kg/m 3

Loss of pressure at linear sections represents the relation bandwidth channel to a known throughput coefficient, and the result of division must be raised to the second power:

P = (G/Kvs) 2

• P—pressure loss, bar
• G—actual coolant flow, m 3 /hour
• Kvs - throughput, m 3 / hour

Pre-balancing the system

The most important final goal of the hydraulic calculation of the heating system is to calculate the throughput values ​​at which a strictly dosed amount of coolant with a certain temperature is supplied to each part of each heating circuit, which ensures normalized heat release on the heating devices. This task seems difficult only at first glance. In reality, balancing is accomplished by control valves that limit the flow. For each valve model, both the Kvs coefficient for the fully open state and a graph of the change in the Kv coefficient for different degrees of opening of the control rod are indicated. By changing the capacity of the valves, which are usually installed at the connection points of heating devices, it is possible to achieve the desired distribution of the coolant, and therefore the amount of heat transferred by it.

There is, however, a small nuance: when the capacity changes at one point in the system, not only the actual flow rate in the area in question changes. Due to a decrease or increase in flow, the balance in all other circuits changes to some extent. If we take, for example, two radiators with different thermal power, connected in parallel with a counter-movement of the coolant, then with an increase in the throughput of the first device in the circuit, the second one will receive less coolant due to an increase in the difference in hydrodynamic resistance. On the contrary, when the duct decreases due to control valve all other radiators further down the chain will receive a larger volume of coolant automatically and will need additional calibration. Each type of wiring has its own balancing principles.

Software systems for calculations

Obviously, performing manual calculations is justified only for small heating systems with a maximum of one or two circuits with 4-5 radiators in each. More complex systems heating with thermal power over 30 kW require integrated approach when calculating hydraulics, which expands the range of tools used far beyond the limits of a pencil and a sheet of paper.

Today there are enough a large number of software, provided by the largest heating equipment manufacturers such as Valtec, Danfoss or Herz. In similar software systems To calculate the behavior of hydraulics, the same methodology that was described in our review is used. First, it is modeled in a visual editor exact copy the designed heating system, for which data on thermal power, type of coolant, length and height of pipeline differences, used fittings, radiators and underfloor heating coils are indicated. The program library contains a wide range of hydraulic devices and fittings; for each product, the manufacturer has determined the operating parameters and basic coefficients in advance. If desired, you can add third-party device samples if the required list of characteristics is known for them.

At the end of the work, the program makes it possible to determine the appropriate conditional pass pipes, select sufficient flow and pressure of circulation pumps. The calculation is completed by balancing the system, while during the simulation of hydraulic operation, the dependencies and influence of changes in the capacity of one node of the system on all others are taken into account. Practice shows that mastering and using even paid software products turns out to be cheaper than if the calculations were entrusted to contract specialists.

Introduction
1 area of ​​use
2. Normative references
3. Basic terms and definitions
4. General provisions
5. Qualitative characteristics of surface runoff residential areas and enterprise sites
5.1. Selection of priority indicators of surface runoff pollution during design treatment facilities
5.2. Determination of calculated concentrations of pollutants when diverting surface runoff for treatment and releasing into water bodies
6. Systems and structures for draining surface runoff from residential areas and enterprise sites
6.1. Surface drainage systems and schemes Wastewater
6.2. Determination of estimated costs of rain, melt and drainage water in rainwater sewers
6.3. Determination of the estimated wastewater flow rates of a semi-separate sewer system
6.4. Regulation of wastewater flows in the storm drainage network
6.5. Surface runoff pumping
7. Estimated volumes of surface wastewater from residential areas and enterprise sites
7.1. Determination of average annual volumes of surface wastewater
7.2. Definition estimated volumes rainwater discharged for treatment
7.3. Determination of the estimated daily volumes of melt water discharged for treatment
8. Determination of the design capacity of surface runoff treatment facilities
8.1. Estimated capacity of treatment facilities accumulative type
8.2. Estimated productivity of flow-type treatment facilities
9. Conditions for the removal of surface runoff from residential areas and enterprise sites
9.1. General provisions
9.2. Determination of permissible discharge standards (VAT) of substances and microorganisms when releasing surface wastewater into water bodies
10. Surface runoff treatment facilities
10.1. General provisions
10.2. Selecting the type of treatment facility based on the principle of water flow regulation
10.3. Basic technological principles
10.4. Cleaning surface runoff from large mechanical impurities and debris
10.5. Separation and regulation of wastewater treatment plants
10.6. Purification of wastewater from heavy mineral impurities (sand collection)
10.7. Accumulation and preliminary clarification of wastewater using static settling method
10.8. Reagent treatment of surface runoff
10.9. Surface runoff treatment using reagent sedimentation
10.10. Treatment of surface runoff using reagent flotation
10.11. Purification of surface runoff using contact filtration
10.12. Additional purification of surface runoff by filtration
10.13. Adsorption
10.14. Biological treatment
10.15. Ozonation
10.16. Ion exchange
10.17. Baromembrane processes
10.18. Disinfection of surface runoff
10.19. Waste management technological processes surface wastewater treatment
10.20. Basic requirements for control and automation of technological processes for surface wastewater treatment
Bibliography
Appendix A. Terms and Definitions
Appendix B. Meaning of rain intensity values
Appendix B. Parameter values ​​for determining the estimated flow rates in rainwater sewer collectors
Appendix D. Territory zoning map Russian Federation along the layer of melt runoff
Appendix E. Map of zoning of the territory of the Russian Federation according to coefficient C
Appendix E. Methodology for calculating the volume of a reservoir for regulating surface runoff in a storm drainage network
Appendix G. Methodology for calculating productivity pumping stations for pumping surface runoff
Appendix I. Methodology for determining the value of the maximum daily rainfall layer for residential areas and enterprises of the first group
Appendix K. Methodology for calculating the maximum daily precipitation layer with a given probability of exceedance
Appendix L. Normalized deviations from the mean value of the ordinates of the logarithmically normal distribution curve Ф at different meanings security and asymmetry coefficient
Appendix M. Normalized deviations of the ordinates of the binomial distribution curve Ф for different values ​​of security and asymmetry coefficient
Appendix H. Average daily precipitation layers Hsr, coefficients of variation and asymmetry for various territorial regions of the Russian Federation
Appendix P. Methodology and example of calculating the daily volume of melt water discharged for treatment Introduction
1 area of ​​use
2. Legislative and regulatory documents
3. Terms and definitions
4. General provisions
5. Qualitative characteristics of surface runoff from residential areas and enterprise sites
5.1. Selection of priority indicators of surface runoff pollution when designing treatment facilities
5.2. Determination of calculated concentrations of pollutants when surface runoff is diverted for treatment and released into water bodies
6. Systems and structures for draining surface runoff from residential areas and enterprise sites
6.1. Systems and schemes for the disposal of surface wastewater
6.2. Determination of the estimated flow rates of rain, melt and drainage water in rainwater sewer collectors
6.3. Determination of the estimated wastewater flow rates of a semi-separate sewer system
6.4. Regulation of wastewater flows in the storm drainage network
6.5. Surface runoff pumping
7. Estimated volumes of surface wastewater from residential areas and enterprise sites
7.1. Determination of average annual volumes of surface wastewater
7.2. Determination of the estimated volumes of rainwater discharged for treatment
7.3. Determination of the estimated daily volumes of melt water discharged for treatment
8. Determination of the design capacity of surface runoff treatment facilities
8.1. Estimated productivity of storage-type treatment facilities
8.2. Estimated productivity of flow-type treatment facilities
9. Conditions for the removal of surface runoff from residential areas and enterprise sites
9.1. General provisions
9.2. Determination of permissible discharge standards (VAT) of substances and microorganisms when releasing surface wastewater into water bodies
10. Surface runoff treatment facilities
10.1. General provisions
10.2. Selecting the type of treatment facility based on the principle of water flow regulation
10.3. Basic technological principles
10.4. Cleaning surface runoff from large mechanical impurities and debris
10.5. Separation and regulation of wastewater treatment plants
10.6. Purification of wastewater from heavy mineral impurities (sand collection)
10.7. Accumulation and preliminary clarification of wastewater using static settling method
10.8. Reagent treatment of surface runoff
10.9. Surface runoff treatment using reagent sedimentation
10.10. Treatment of surface runoff using reagent flotation
10.11. Purification of surface runoff using contact filtration
10.12. Additional purification of surface runoff by filtration
10.13. Adsorption
10.14. Biological treatment
10.15. Ozonation
10.16. Ion exchange
10.17. Baromembrane processes
10.18. Disinfection of surface runoff
10.19. Treatment of waste from technological processes of surface wastewater treatment
10.20. Basic requirements for control and automation of technological processes for surface wastewater treatment
Bibliography
Appendix 1. Rain intensity values
Appendix 2. Parameter values ​​for determining the estimated flow rates in rainwater sewer collectors
Appendix 3. Map of zoning of the territory of the Russian Federation by melt runoff layer
Appendix 4. Map of zoning of the territory of the Russian Federation according to coefficient C
Appendix 5. Methodology for calculating the volume of a reservoir for regulating surface runoff in a storm drainage network
Appendix 6. Methodology for calculating the productivity of pumping stations for pumping surface runoff
Appendix 7. Methodology for determining the maximum daily layer of rainwater runoff for residential areas and enterprises of the first group
Appendix 8. Methodology for calculating daily precipitation with a given probability of exceedance (for enterprises of the second group)
Appendix 9. Normalized deviations from the average value of the ordinates of the logarithmically normal distribution curve Ф at different values ​​of security and asymmetry coefficient
Appendix 10. Normalized deviations of the ordinates of the binomial distribution curve Ф for different values ​​of security and asymmetry coefficient
Appendix 11. Average daily precipitation layers Hsr, coefficients of variation and asymmetry for various territorial regions of the Russian Federation
Appendix 12. Methodology and example for calculating the daily volume of melt water discharged for treatment

Regulatory and methodological documents are provided that regulate the design of systems for the disposal and purification of surface (rain, melt, irrigation) wastewater from residential areas and enterprise sites, as well as comments on the provisions of SP 32.13330.2012 “Sewerage. External networks and structures" and "Recommendations for calculating systems for collecting, discharging and purifying surface runoff from residential areas and enterprise sites and determining the conditions for its release into water bodies" (JSC "NII VODGEO"). These documents allow for the diversion for treatment of the most contaminated part of surface runoff in an amount of at least 70% of the annual volume of runoff for residential areas and enterprise sites that are close to them in terms of pollution, and the entire volume of runoff from the sites of enterprises, the territory of which may be polluted with specific substances containing toxic substances. properties or significant content organic matter. Common design practices reviewed engineering structures separate and all-alloy sewerage systems that allow short-term discharge of part of the wastewater during intense (storm) rains of rare frequency through separation chambers (storm discharges) into a water body. Situations related to refusals of the territorial departments of State Expertise and Rosrybolovstvo to approve the implementation of activities on designed objects are considered. capital construction on the basis of Article 60 of the Water Code of the Russian Federation, which prohibits the discharge of wastewater into water bodies that has not undergone sanitary treatment and neutralization.

Keywords

List of cited literature

1. Danilov O. L., Kostyuchenko P. A. Practical guide to the selection and development of energy-saving projects. – M., JSC Tekhnopromstroy, 2006. pp. 407–420.
2. Recommendations for calculating systems for the collection, disposal and purification of surface runoff from residential areas, enterprise sites and determining the conditions for its release into water bodies. Addendum to SP 32.13330.2012 “Sewerage. External networks and structures" (updated edition of SNiP 2.04.03-85). – M., JSC “NII VODGEO”, 2014. 89 p.
3. Vereshchagina L. M., Menshutin Yu. A., Shvetsov V. N. O regulatory framework design of systems for disposal and treatment of surface wastewater: IX scientific and technical conference “Yakovlev Readings”. – M., MGSU, 2014. pp. 166–170.
4. Molokov M.V., Shifrin V.N. Treatment of surface runoff from the territories of cities and industrial sites. – M.: Stroyizdat, 1977. 104 p.
5. Alekseev M.I., Kurganov A.M. Organization of drainage of surface (rain and melt) runoff from urbanized areas. – M.: Publishing house ASV; St. Petersburg, St. Petersburg State University of Civil Engineering, 2000. 352 p.

FEDERAL AGENCY OF THE RUSSIAN FEDERATION FOR
CONSTRUCTION AND HOUSING AND COMMUNAL SERVICES
(ROSSTROY)

Introduction Section 3. General provisions Section 4. Qualitative characteristics of surface runoff from residential areas and enterprise sites 4.1. Selection of priority indicators of surface runoff pollution when designing treatment facilities 4.2. Determination of calculated concentrations of pollutants when surface runoff is diverted for treatment and released into water bodies Section 5. Quantitative characteristics of surface runoff from residential areas and enterprise sites 5.1. Determination of average annual volumes of surface wastewater 5.2. Determination of the estimated volumes of surface wastewater when diverted for treatment 5.3. Determination of the estimated flow rates of rain and melt water in rainwater sewer collectors 5.4. Determination of the estimated flow rates of surface runoff when diverted for treatment and into water bodies Section 6. Conditions for the removal of surface runoff from residential areas and enterprise sites 6.1. General provisions 6.2. Determination of MPC standards for pollutants when releasing surface wastewater into water bodies Section 7. Systems and structures for the collection and disposal of surface runoff from residential areas and enterprise sites 7.1. Surface runoff collection and disposal schemes 7.2. Structures for regulating surface runoff during disposal for treatment and methods for their calculation 7.3. Surface runoff pumping 7.4. Determination of the design capacity of treatment facilities Section 8. Treatment of surface runoff from residential areas and enterprise sites 8.1. General provisions 8.2. Mechanical cleaning 8.3. Wastewater treatment by flotation 8.4. Filtration 8.5. Reagent treatment of surface runoff 8.6. Biological treatment 8.7. Ion exchange 8.8. Adsorption 8.9. Ozonation 8.10. Sludge treatment 8.11. Disinfection of surface runoff Legend: BIBLIOGRAPHY Appendix 1 Classification of regions of the Russian Federation depending on climatic conditions Appendix 2 Values ​​of rain intensity q20 Appendix 3 Values ​​of parameters n, mr, γ for determining the estimated flow rates in rainwater sewer collectors Appendix 4 Average duration rain on a day with precipitation Appendix 5 Methodology for constructing a graph of the probability distribution function of daily rain layers and an example of calculating the daily rain layer with a given period of a single excess of P< 1 года Appendix 6 Methodology for calculating the daily precipitation layer with a given probability of exceedance Appendix 7 Schemes for regulating surface runoff and methods for calculating the flow of wastewater discharged for treatment and into water bodies Appendix 8 Methodology for calculating the productivity of pumping stations for pumping surface runoff

Introduction

3. Rules for the use of public water supply and sewerage systems in the Russian Federation.

The recommendations were developed by a team of specialists from the State Scientific Center of the Russian Federation, Federal State Unitary Enterprise "Research Institute VODGEO" under the scientific supervision of a Doctor of Technical Sciences, consisting of: Candidates of Technical Sciences, Doctor of Technical Sciences, Engineer, Candidates of Technical Sciences, Doctor of Technical Sciences.

When developing the Recommendations, data from field studies obtained by specialists from the Leningrad Scientific Research Institute of AKH named after. , VNIIVO and a number of industry research organizations at enterprises in various industries, as well as data from experience in operating treatment facilities for surface runoff from urban areas and industrial enterprises, designed and built over the past 30 years.

The basis for the recommended calculation of systems for the collection and disposal of surface wastewater is the method of limiting intensities, developed and later developed by engineer, Doctor of Technical Sciences, Candidate of Technical Sciences, Doctors of Technical Sciences and A. M. Kurganov.

The authors express special gratitude to the chief specialist of the State Unitary Enterprise “Soyuzvodokanalproekt”, candidate of technical sciences for their assistance in preparing the Recommendations, as well as to the participants of the seminar of the VODGEO Research Institute “Systems for the collection, disposal and purification of surface runoff from residential areas of cities and industrial enterprises” (April 6-7, 2005 g., Moscow), dedicated to the new edition of the Recommendations, for the comments and suggestions expressed.

1 With the release of these recommendations, “Temporary recommendations for the design of structures for treating surface runoff from the territories of industrial enterprises and calculating the conditions for its release into water bodies,” published by VNII VODGEO in 1983, become invalid.

Section 1. Legislative and regulatory documents

1. Water Code of the Russian Federation of November 16, 1995.

3. Security rules surface waters. - M., 1991.

4. SanPiN 2.1.5.980-00. Hygienic requirements to the protection of surface waters.

5. GOST 17.1.3.13-86. General requirements to the protection of surface waters from pollution.

6. Rules for using systems public water supply and sewerage in the Russian Federation. Approved by Decree of the Government of the Russian Federation of February 12, 1999 No. 000.

7. SNiP 2.04.03-85. Sewerage. External networks and structures.

8. SNiP 23-01-99. Construction climatology.

9. GOST 17.1.1.01-77. Protection of Nature. Hydrosphere. Use and protection of water. Basic terms and definitions.

10. GOST 17.1.3.13-86. Protection of Nature. Hydrosphere. Classification of water bodies.

11. SanPiN 2.2.1/2.1.1.1200-03. Sanitary and epidemiological rules and regulations.

12. GOST 27065-86. Water quality Terms and Definitions.

13. GOST 19179-73. Hydrology of land. Terms and Definitions.

14. List of fishery standards: maximum permissible concentrations (MPC) and approximate safe levels impact (OBUV) harmful substances for water from water bodies with fishery purposes. Approved by order of Roskomrybolovstvo dated June 28, 1999 No. 96.

15. GN 2.1.5.1315-03. Maximum permissible concentrations (MPC) chemical substances in the water of water bodies for domestic, drinking and cultural water use. Hygienic standards. Approved and put into effect by Decree of the Chief State Sanitary Doctor of the Russian Federation dated April 30, 2003 No. 78.

16. GN 2.1.5.1316-03. Approximately permissible levels(TAC) of chemical substances in the water of water bodies for domestic, drinking and cultural water use. Hygienic standards. Approved and put into effect by Decree of the Chief State Sanitary Doctor of the Russian Federation dated January 1, 2001 No. 78.

Section 2. Terms and definitions

For the purposes of this document, the following terms and definitions apply:

STORING CAPACITY(surface runoff storage tank) - a structure for receiving, collecting and averaging the flow and composition of surface wastewater from residential areas and enterprise sites for the purpose of their subsequent purification.