City heat supply scheme: classification of systems

Accord­ing to reports, the length of ther­mal sys­tems in EU has reached 185 thou­sand km. This fig­ure does not ful­ly reveal the scale, branch­ing and com­plex­i­ty of their cre­ation. That is why this arti­cle will address issues relat­ed to the design of heat­ing net­works and the heat sup­ply of set­tle­ments in our vast.

Any heat sup­ply sys­tem is designed for heat­ing, hot water sup­ply and ven­ti­la­tion of build­ings and struc­tures of var­i­ous nature, as well as indus­tri­al facil­i­ties. As a rule, heat sources are boil­er hous­es and CHPPs (com­bined heat and pow­er plants) that pro­duce heat ener­gy by burn­ing hydro­car­bons.

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The main prod­uct of ther­mal ener­gy sources is steam and hot water, which are sub­ject to seri­ous require­ments. The thing is that when an untreat­ed liq­uid is heat­ed, some of the sol­id par­ti­cles and min­er­als con­tained in it are deposit­ed on the walls of the pipeline and equip­ment, which sig­nif­i­cant­ly reduces their ser­vice life. To remove impu­ri­ties, almost every boil­er house and CHP has water treat­ment and soft­en­ing points.

Any heat sup­ply sys­tem con­sists of a heat source and trans­port sys­tems through which it is deliv­ered to the con­sumer. The lat­ter are heat-using equip­ment oper­at­ing in engi­neer­ing sys­tems.

On the ter­ri­to­ry of Europe, the most com­mon steel pipeline for heat sup­ply. In addi­tion to pipes, in the con­struc­tion of heat­ing net­works, they use: sup­ports, expan­sion joints, con­trol, pump­ing equip­ment, heat­ing points.

Classification and design features

Heat sup­ply sys­tems are clas­si­fied as fol­lows:

  1. Decen­tral­ized. Deliv­ery of the coolant is car­ried out from the boil­er room or from the house (apart­ment) heat gen­er­a­tor.Decentralized heating scheme
  2. Cen­tral­ized heat­ing sys­tems. There are four vari­eties of them:
    • Inter­ci­ty.
    • Urban.
    • Dis­trict (with­in the dis­trict of one set­tle­ment).
    • Heat sup­ply of a group of build­ings.

City heat­ing sys­tems are dis­tin­guished by:

  1. The type of coolant pro­duced, which, in turn, is clas­si­fied accord­ing to ther­mal poten­tial: up to 150 ° C; from 150 to 400°C; from 400°С.CHP

    Impor­tant! The domes­tic sec­tor uses a low-grade coolant, where the tem­per­a­ture in the sup­ply pipe does not exceed 150°C. and the pres­sure is 1.4 MPa. High-poten­tial — in steam sys­tems it is used in heat sup­ply schemes of enter­pris­es.

  2. Heat pro­duc­tion method.
    • Heat gen­er­a­tion takes place sep­a­rate­ly from elec­tric­i­ty gen­er­a­tion.
    • Simul­ta­ne­ous receipt of heat and elec­tric­i­ty.

      Impor­tant! The sec­ond method of dis­trict heat­ing wins sig­nif­i­cant­ly in terms of effi­cien­cy. It’s all about the pos­si­bil­i­ty of simul­ta­ne­ous­ly gen­er­at­ing elec­tric­i­ty and heat by burn­ing low-grade hydro­car­bons, which are impos­si­ble or extreme­ly dif­fi­cult to use in boil­er hous­es.

  3. The method of sup­ply­ing hot water from the source to the con­sumer.
    • Open means draw­ing water for hot water sup­ply direct­ly from the heat source.
    • With the closed method, the coolant is used exclu­sive­ly for heat­ing water from the water sup­ply sys­tem in spe­cial devices — boil­ers.
  4. pipeline num­ber. The most wide­spread in EU are two-pipe sys­tems.
  5. Accord­ing to the method of pro­vid­ing the con­sumer with heat, the heat sup­ply sys­tems of cities are:
    • Designs where the con­sumer is con­nect­ed direct­ly to the heat­ing net­works. Heat­ing points are locat­ed at the junc­tion point.
    • Sys­tems where dis­tri­b­u­tion points are locat­ed between the heat pro­duc­er and the con­sumer. In them, the ini­tial char­ac­ter­is­tics of heat­ed water can vary based on the actu­al heat con­sump­tion.

The advan­tages of the sec­ond method are obvi­ous: when plac­ing dis­tri­b­u­tion points, it is pos­si­ble to reduce ini­tial costs due to the reduc­tion in equip­ment used.

Basic heat supply schemes

Basic schemesToday in EU, two schemes of heat sup­ply sys­tems are used, dif­fer­ing in com­po­si­tion and design.

  • The first option involves the sup­ply of heat­ed water for heat­ing and hot water needs through the same trans­port net­works. Water is drawn from the sup­ply line, which cre­ates a sit­u­a­tion where dif­fer­ent vol­umes of water flow through two branch­es of the pipeline.
  • Accord­ing to the sec­ond scheme, heat­ed water is sup­plied only for heat­ing needs. To cre­ate a hot water sup­ply, points for heat­ing tap water with a heat car­ri­er are used.

The advan­tages of the first scheme are the low cost of the project (heat exchang­ers are not required) and oper­a­tion. The dis­ad­van­tage is high water loss­es and dete­ri­o­ra­tion of its qual­i­ty.

The advan­tages of the sec­ond are sta­ble tem­per­a­ture and water qual­i­ty, ease of con­trol. The dis­ad­van­tage is the rise in the cost of hot water sup­ply for sub­scribers, due to the use and main­te­nance of addi­tion­al equip­ment (boil­ers).

Impor­tant: the devel­op­ment of a city heat sup­ply scheme is the most impor­tant process to pro­vide the pop­u­la­tion, indus­tri­al and cul­tur­al facil­i­ties with heat and hot water with min­i­mal envi­ron­men­tal impact.


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