Determination of the Number of Heat Generators of an Independent

Heat Supply Source When Planning the Development of the Urban

Environment

Dmitry Kitaev

a

, Svetlana G. Tulskaya

b

and Galina N. Martynenko

c

Voronezh State Technical University, Voronezh, Russia

Keywords: Development of the Urban Environment, Heat Supply, Heat Generator, Coolest Month Mode, Heating, Hot

Water Supply, Number of Heat Generators

Abstract: The article concentrates on the selection of the number of boilers in boiler houses of independent heat supply

sources. The analysis of the current standards to justify the selection of the number of boilers is carried out.

For settlements, presented in the latest revision of climatological data, the values of the heat consumption

reduction coefficient for heating needs in the cold month mode were obtained, the possible range of its change

was established. Using the example of a low power boiler house, a significant influence of the climatic data

of the cold month on the number of heat generators is shown. Based on the established range of variation of

the heat consumption reduction coefficient, the ratio of heat consumption for heating and hot water supply for

multi-apartment residential buildings with independent heat supply sources, the range of the possible number

of boilers was established. The ranges of the heat consumption reduction coefficient for heating needs have

been found, which make it possible to nearly determine the corresponding number of required heat generators.

1 INTRODUCTION

The heat supply system is part of the engineering

infrastructure of cities. The sustainable development

of city development is closely related to the

development of the heat supply system. When

planning general plans of cities, it is necessarily to

take into account the development of generating

capacities and the system of transporting heat energy.

The federal law on heat supply in the Russian

Federation obliged each settlement to develop and

approve heat supply schemes, that determine the

development of the entire system as a whole, and also

update them annually. Often the planning horizon of

the city general plan and the heat supply scheme

coincide, i.e. their development is synchronous. In

addition, the heat supply scheme during development

is linked to the water supply and gas supply schemes.

The approach to sustainable development of

territories and engineering infrastructure should be

complex (Kitaev, 2010; Semenov, 2010)

a

https://orcid.org/0000-0003-4148-1261

b

https://orcid.org/0000-0003-4822-4938

c

https://orcid.org/0000-0002-2133-6051

With the strategy of the sustainable development

of the heat supply system, it is necessary to determine

the possibility of connecting the promising city

development to the existing systems. The centralized

system does not always have the necessary capacity

reserves, and in some cases, the construction of long

underground networks with generation sources is not

economically feasible. In recent decades, there has

been an increase in the number of introduction of

independent heat supply sources in the housing and

utility services. In urban infrastructure, integrated

heat supply sources are widely used, represented by

built-in, attached and roof boiler houses (Semenov,

2011; Khavanov, 2005; Minin, 2016). Independent

heat supply is widely used to provide energy to high-

rise buildings in close city development, where it is

impossible to use underground centralized heating

pipelines (Gapeeva, 2018). The main advantage of

such systems is the ability to accurately regulate the

load of heat consumption systems, and the

disadvantages are noise and vibration impacts.

Beyond the scope of the article, we will drop the

Kitaev, D., Tulskaya, S. and Martynenko, G.

Determination of the Number of Heat Generators of an Independent Heat Supply Source When Planning the Development of the Urban Environment.

DOI: 10.5220/0010586801010106

In Proceedings of the International Scientiﬁc and Practical Conference on Sustainable Development of Regional Infrastructure (ISSDRI 2021), pages 101-106

ISBN: 978-989-758-519-7

Copyright

c

2021 by SCITEPRESS – Science and Technology Publications, Lda. All rights reserved

101

subject of the need for a decentralized approach to

heat supply, its disadvantages and advantages over

the priority direction of the development of

centralized heat supply in the Russian Federation. In

recent years, along with centralized, independent heat

supply has been widely developing, this is a reality of

our time (Kitaev, 2010; Melnikov,2015).

Determining the number of boilers, installed in

boiler houses, is an important stage in the design of a

heat supply system (Martynenko, 2018; Semenov,

2015). The reliability of heat supply, operating costs,

and the cost of heat generation depend on the correct

selection. The selection of the number of boilers is a

multivariate task, that often requires creative

approach. The number of installed boilers in the

boiler house is influenced by many factors, such as

the consumer reliability category, climatic data of the

design area, the value of the design heat currents for

heating, ventilation, hot water supply and technology,

the value of the boiler house's needs, the minimum

value of the heat load of the heat generator itself

(Zbaraz, 2019; Panferov, 2020; Fang, 2015). Modern

standards in the field of heat supply recommend,

when determining the design capacity, to take into

account additionally the own needs of boiler houses

and waste of the heat energy during the transportation

of the heat carrier (in heating networks). The correct

value of the boiler house's own needs can be fulfilled

only after the end of the calculation and selection of

all equipment and pipelines, but even in this case,

some data, for example, on the number of boiler start-

ups, will have to be taken approximately. In addition,

in boiler houses of centralized sources, the values of

their own needs can reach 12-15% of the output,

especially in the case of using fuel oil and coal dust.

A similar situation is with waste of the heat energy in

networks, the actual values of which can reach 15-

20%. With a decrease in the capacity of the boiler

house, own needs and waste in the networks decrease,

especially when using gaseous fuel. In integrated heat

supply sources, their own needs are minimal, and

there are no networks.

Domestic and foreign authors pay great attention

to the issues of influence of the number of installed

boilers, modes of their load during the year on the

efficiency of the boiler house, and the heat supply

system as a whole. Measures are proposed to improve

the efficiency of existing heat supply sources (Kitaev,

2020; Chicherin, 2019; Terhan and Comakli, 2017).

2 RESEARCH METHODOLOGY

Modern design standards contain recommendations

for the selection of the required number of boilers.

Let's consider them in more detail. In the current SP

124.13330.2012 (Heating networks), it is

recommended in case of emergencies in the

centralized heating system during the entire repair-

recovery period to provide: supply of 100% of the

required heat to consumers of the first category

(unless other modes are provided for by the contract);

heat supply for heating and ventilation to housing and

utility and industrial consumers of the second and

third categories in the amount (depending on the

design temperature of the outside air from 78 to 91%);

consumer-specified emergency mode of steam and

process hot water consumption; consumer-specified

emergency heat mode of operation of non-

disconnectable ventilation systems; average daily

heat consumption for the heating period for hot water

supply (if it is impossible to turn it off).

SP.89.13330.2016 (Boiler-house plants)

recommends to select the number and capacity of

boilers, installed in the boiler house, providing: the

design capacity of the boiler house; stable operation

of boilers at the minimum permissible load during the

warm season. In case of failure of the boiler with

maximum output in the boiler houses of the first

category, the remaining boilers must provide heat

energy to consumers of the first category in an

amount determined by: the minimum permissible

loads (regardless of the outside air temperature) - for

technological heat consumption and ventilation

systems; mode of the coldest month - for heating and

hot water supply. In case of failure of one boiler,

regardless of the category of the boiler house, the

amount of heat, supplied to consumers of the second

and third categories, should be provided in certain

amounts (as in the SP Heating networks). It should be

noted, that these requirements do not apply to

independent heat supply sources, integrated into

buildings.

SP 373.1325800.2018 (Independent heat supply

sources) recommends, in the event of failure of the

boiler with maximum output, to provide heat with

remaining in operation for the following purposes:

technological heat supply of the ventilation system -

in an amount, determined by the minimum

permissible loads (regardless of the outside air

temperature); heating, ventilation and hot water

supply - in the amount, determined by the mode of the

coldest month.

From the above recommendations, it can be

concluded, that in the absence of a ventilation load

ISSDRI 2021 - International Scientiﬁc and Practical Conference on Sustainable Development of Regional Infrastructure

102

(usually multi-apartment residential buildings), the

requirements for independent heat supply sources and

other boiler houses of the first category are the same

in terms of reliability.

3 RESULTS

Putting aside the heat load for the ventilation system,

it is usually absent for a residential building, then

independent source need, in case of failure, to provide

a load of heating and hot water supply in the cold

month mode.

In this case, when determining the power value of

the boiler house when the largest boiler fails, it will

be necessary to evaluate the heat consumption

reduction coefficient for heating needs by the well-

known formula

0

i

х

м

i

tt

K

tt

.

To evaluate the coefficient K, the data of SP

131.13330.2018 (Construction climatology) were

analyzed for the presented settlements (467

settlements). For the majority of the territory of the

Russian Federation (except for two settlements), the

coldest month is January. Table 1 presents climatic

data and the value of the coefficient K for a sample of

51 settlements, that are regional capitals.

Table 1: Values of the heat consumption reduction coefficient.

Settlement K Settlement K Settlement K

Krasnoyarsk 0.618 Maykop 0.517 Yakutsk 0.817

Sevastopol 0.514 Blagoveshchensk 0.790 Yekaterinburg 0.634

St. Petersburg 0.586 Arkhangelsk 0.620 Vladikavkaz 0.674

Magadan 0.748 Astrakhan 0.585 Smolensk 0.593

Yoshkar-Ola 0.590 Ufa 0.624 Stavropol 0.581

Saransk 0.592 Ulan-Ude 0.787 Kazan 0.604

Moscow 0.600 Vladimir 0.616 Tomsk 0.633

Murmansk 0.594 Vologda 0.594 Kyzyl 0.728

Naryan-Mar 0.633 Makhachkala 0.561 Tyumen 0.643

Nizhny Novgorod 0.585 Chita 0.791 Ulyanovsk 0.559

Novosibirsk 0.649 Irkutsk 0.714 Khabarovsk 0.815

Orenburg 0.618 Nalchik 0.578 Abakan 0.665

Perm 0.604 Kaliningrad 0.546 Chelyabinsk 0.660

Vladivostok 0.765 Sochi 0.600 Grozny 0.577

Pskov 0.552 Cherkessk 0.581 Cheboksary 0.620

Saratov 0.621 Vorkuta 0.649 Anadyr 0.686

Rostov-on-Don 0.589 Petropavlovsk-Kamchatsky 0.692 Yuzhno-Sakhalinsk 0.790

Fig. 1. shows the values of the coefficient K for

all settlements

Figure 1: Values of the coefficient K.

From these calculations, it follows, that the

minimum value of the coefficient K = 0.5 is observed

for Klepnino (Rep. Of Crimea), and the maximum for

the rural settlement of Kalakan is K = 0.949. The

maximum value is an exception and is observed only

for one settlement, moreover, with a small population

and consisting of individual residential development.

Putting aside the value of 0.949, then the following

will be K = 0.863 for Zavitinsk, Amur Region.

It follows from the calculations, that the load of

heating and ventilation systems in the coldest month

mode can range from 0.5 to 0.863 of the design one.

Consider an example of determining the number

of heat generators with the following initial data:

maximum heating load

max

o

Q

= 3.4 MW; average load

of hot water supply during the heating period

з

гвс

Q

=

0.96 MW, in non-heating period

л

гвс

Q

= 0.768 MW;

own needs of the boiler house are 1%. Taking into

Determination of the Number of Heat Generators of an Independent Heat Supply Source When Planning the Development of the Urban

Environment

103

account the initial data, the design capacity of the

boiler house in the heating period will be

з

р

Q

= 4.4

MW.

Table 2 shows the results of calculating the

number of boilers, that meet the requirements for

ensuring the load of heating and hot water supply in

the event of the failure of the largest boiler, for

various values of the coefficient K. Boilers of the

KVa type with a unit capacity of N1 1, 1.25, 1.6, 2,

2.5 MW were considered. In table N1 is the result of

dividing

з

р

Q

by the number of boilers. The last

column shows the load values in the summer period

∆,%. The minimum value for the type of boiler under

consideration is 40%.

Table 2: Number of boilers.

Coefficient

K

N

1

,

MW

N

1

,

MW

N

umber of

boilers n,

p

cs

∆,%

0.5 1.468 1.6 3 48

0.6 1.468 1.6 3 48

0.7 1.101 1.25 4 61.4

0.8 1.101 1.25 4 61.4

0.863 0.881 1 5 76.8

As can be seen from Table 2, climatic data have a

significant impact on the number of boilers. In the

example considered, the number of boilers is from

three to five. The minimum number of boilers, that

meet the requirement of standards, is three.

The heat load of the hot water supply system does

not depend on the outside temperature, therefore, for

the coldest month mode, the heat supply is

determined by the formula

max max

(0,5 0,863)

з

з

х

м o гвс o гвс

QQKQ Q Q

. (1)

4 DISCUSSION OF RESULTS

Consider the range of ratios of the maximum heat

consumption for hot water supply and heating 0.2≤

max

гвс

Q

/

max

o

Q

≤1, used in a number of standards (SP 41-

101-95 "Designing heat points", STO NP "RT"

70264433-5-1-2009 "Recommendations on the

design of heat points, located in buildings"). This

range of load ratios is predominant for residential

buildings (Zbaraz, 2019; Panferov, 2020; On the

analysis, 2017). Taking into account the ratio between

the maximum and average heat consumption for hot

water supply 2.4, given in SP 373.1325800.2018

"Independent heat supply sources", we obtain the

range 0.083≤

ср

гвс

Q

/

max

o

Q

≤0.417. Therefore, the

value of the average consumption for hot water

supply is in the range of 0.083

max

o

Q

≤

ср

гвс

Q

≤0.417

max

o

Q

. Substituting the minimum and maximum

values of the ranges into expression (1), we get:

max max max

0,5 0,083 0,583

хм o оо

QQ Q Q

;

max max max

0,863 0,4167 1,28

хм o оо

QQ QQ

As a result, without taking into account own needs,

we obtain the possible range of heat load for the cold

month

0.583

max

o

Q

≤

х

м

Q

≤1.28

max

o

Q

. (2)

The algorithm for selecting the number of boilers

is shown in Figure 2 and contains the following

stages.

Figure 2: Block scheme of determining the number of

boilers.

1. Based on the known load of the heating period,

the maximum and minimum value of the load of the

hot water supply and the boiler house is determined.

In accordance with the accepted restraints, the design

capacity of the boiler house can be in the range of

1.083

max

o

Q

≤

кот

Q

≤1.4167

max

o

Q

. (3)

2. The unit capacity (of one boiler) of the boiler

N1, installed in the boiler house, is determined by

dividing the design capacity by the number of boilers

n. In the initial approximation, the minimum

allowable is taken, equal to two.

3. According to the catalog of boilers, we select a

boiler with a capacity of Ncat equal or greater than

the design N1. We install identical boilers of equal

capacity, as people try to do in practice.

ISSDRI 2021 - International Scientiﬁc and Practical Conference on Sustainable Development of Regional Infrastructure

104

4. In order to fulfill the condition of providing the

calculated load of heating and hot water supply in

case of failure of the boiler with maximum output in

the cold month mode, we evaluate the value of the

load Qхм.

5. Check the fulfillment of the inequation N1 (n-

1) ≥ Qхм. If it is valid, then proceed to checking the

fulfillment of the requirement for the minimum boiler

load during the heating period (see cl. 6). If the

inequation is not valid, then go to step 2 and set more

boilers (n + 1), repeat the calculation until the

inequation is valid.

6. We check the fulfillment of the requirement to

provide the minimum boiler load in the non-heating

period

min

N

, when only the hot water supply system

is operating:

л

гвс

Q

/ N1≥

min

N

. If the inequation is

valid, then we print the number of boilers, if not, then

we increase the number of boilers (Cl. 2).

We use the algorithm considered to find the

maximum and minimum number of boilers, installed

in an integrated heat supply source.

Let's introduce additional restraints. We assume,

that according to the catalog of boiler designs, it will

be possible to select a boiler with a capacity Ncat

equal to the design N1. We assume, that it is possible

to select a boiler with an acceptable percentage of

load for the summer period. This will be facilitated by

the minimum value of boilers in the boiler houses of

the housing and utilities services, equal to two, and

the fact, that with an increase in the number of boilers,

the percentage of the minimum load in the summer

period of one boiler increases.

The requirement to provide the design load for the

cold month, when the boiler with maximum output

fails (with the same capacity of the boilers) is

determined by the inequation

1

кот хм

n

QQ

n

.

(4)

The minimum number of boilers is determined by

the expression

1

1

хм

кот

Q

n

Q

.

(5)

Taking into account expressions (2), (3), we

evaluate the values of the minimum and maximum

number of boilers, rounded to integers: nmin =

1.699≈2; nmax = 10.36≈11.

Using expressions (1), (2), (5), taking into account

the inequation 0.083

max

o

Q

≤

ср

гвс

Q

≤0.417

max

o

Q

, the

values of the ranges of the coefficient K for the

corresponding number of boilers, presented in Table

3, were evaluated.

Table 3: Ranges of the heat consumption reduction

coefficient for heating needs for the corresponding number

of boilers.

n 2 3,4,5,6 7 8 9 10 11

K

min

0.5 0.5 0.511 0.531 0.546 0.558 0.568

K

max

0.63 0.861 0.863 0.863 0.863 0.863 0.863

From table 2 it follows, that two boilers cannot be

installed in the range 0.63 < K < 0.863, 3-6 boilers at

0.861 < K, 7 boilers at 0.5 < K < 0.511, 8 boilers at

0.5 < K < 0.531, etc. The determining factor is the

ratio of heat loads for heating and hot water supply.

5 CONCLUSIONS

The analysis of the standard literature allowed to

establish the requirements for providing minimum

consumer loads, affecting the determination of the

number of heat generators. On the basis of modern

climatic data, it has been established established, that

the value of the heat consumption reduction

coefficient for heating needs in the cold month mode

can have a value from 0.5 to 0.863. Taking into

account the data on the ratio of heat consumption for

hot water supply and heating, it was established, that

the number of boilers can be in the range from 2 to

11. The ranges of the heat consumption reduction

coefficient for heating needs are evaluated for the

corresponding number of boilers. The conclusions

obtained are also valid for boiler houses of centralized

heat supply systems of the first category of reliability

in the presence of heating and hot water supply loads.

The results obtained can be used in planning the

development of independent heat supply sources for

urban infrastructure.

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