FI20215627A1 - System and method for transferring district heat - Google Patents

Abstract

The invention relates to a system and a method for transferring district heating, which system comprises - a heat-producing plant (32), which is connected to a watercourse (10) with an inlet line (321), and which is arranged to emit heat in the transfer water taken from the watercourse (10), - a plurality of heat consumers (18), - a regional distribution pipe system (24) for district heating to conduct heat to the area's heat consumers (18), and - a transfer line (50) for hot transfer water to transfer heat from the plant (32) to the heat consumers (18), wherein the plant (32) is at the front end (58) of the transfer line (50), and at the end (59) of the transfer line (50) there are means for transferring heat from the transfer line (50) to the distribution pipe system (24). ). In addition - the hot water transfer line (50) is a unidirectional insulated pipe without return pipe, - the system comprises an outlet pipe (603) for discharging water into the watercourse (10), which discharge end (613) of the outlet pipe (603) is closer to the transfer line (50). ) end (59) than the front end (58), and - is as a return line for transfer water from the outlet pipe (603) to the inlet line (321) of the plant (32) a natural water circuit arranged to operate, preferably a watercourse (10), forming an open circuit for district heating between the discharge end (613) of the outlet pipe (603) and the inlet end (331) of the inlet line (321) of the system (32).

Description

The invention relates to a system and method for the transfer of district heat, the system comprising - at least one heat generating plant connected to a water supply line with an inlet end and adapted to transfer heat to the transfer water taken from the water body, a district heating distribution pipeline for conducting heat to district heat consumers, and - a hot water transfer line for transferring heat from the plant to the heat consumers, where the plant is in the direction of hot transfer water flow at the beginning of the transmission line and means for transferring heat from the transmission line to the distribution pipeline. In the current district heating network ('Suomalainen Kaukolämmitys'', Veli-Matti Mäkelä and Jarmo Tuunanen), district heating is transferred from the power plant to heat consumers as hot water in a closed two-pipe district heating network. The district heating network plays an essential role in the district heating system, as it enables the centralization of heat production in one or more power plants. O 25 Insulated district heating supply and return pipes are typically installed in parallel to run underground. The supply and return pipes are of the same size N and contain numerous pumping stations, valves, measuring devices and control devices. In the supply pipes, the hot N district heating water flows from the power plant to the heat consumers, and in the O 30 return pipes, the district heating water returns to the N power plant when it has cooled down for reheating.

N The district heating network can be very long. For example, if the district heating used in Helsinki were produced at a power plant in Porvoo, the distance between the power plant and the heat consumers would be about 40 km. In that case, the costs of district heating transmission would be significant due to the large number of pipes in the district heating network, and therefore the considerable construction and operating costs as well as network losses. District heating is typically produced as cogeneration of electricity and heat, so that waste heat from power plants can be utilized, which increases the overall efficiency of the power plant. However, the condensate produced by a conventional condensing power plant is typically so cold that it is hardly available for heat production. For cogeneration, therefore, the power plant process needs to be slightly modified. Technical solutions include, for example, a back-pressure power plant and an intake power plant.

The prior art discloses patent publication KR 101897226 B1, which discloses a district heating system in which district heating water is discharged into the sea after heat transfer. In the system described in the publication, the district heating return water is led back to the power plant outlet pipe in the return pipe, from where the water is discharged into the sea. Thanks to the system, the temperature of the water discharged into the sea from the power plant's discharge pipe can be lowered. The object of the invention is to provide an improved system O 25 in district heating transmission to reduce the transmission costs and the need for ro energy. The characteristic features N of the present invention appear from the appended claim 1. It is also an object of the invention to provide an improved method for transferring district heat N. The characteristic features of the present invention appear from the appended claim 15. The system according to the invention for district heating transmission comprises at least one heat generating plant connected to a water supply line with an inlet end and adapted to supply heat to the water supply from a number of heat consumers. a district heating distribution pipeline for conducting heat to the district heat consumers; The hot transfer water transmission line is a one-way insulated pipe without a return pipe, the system includes an outlet pipe for discharging the transfer water into a water system with and the input end of the plant input line. In this way, the number of pipes in the district heating network is considerably smaller compared to the prior art. In this case, construction and operating costs are significantly lower due to lower pumping requirements and lower network losses. Fdullically the water body is at least partly sea. In this case, the heat load caused to the water system by the district heating system is small in proportion to the size of the water system. From an environmental point of view, the best option for O 25 as a water body is the sea. A body of water can be at least 3 into a lake or river.

N = Preferably, the inlet line of the plant is located upstream of the water body, N and the heat consumers are in the direction downstream of the water body O 30 with respect to the inlet line. The return line can be the natural water circulation 3, so that the water returns with the clouds and rain to the upper reaches of the water to the entrance line of the plant. In this case, the natural water circulation replaces the need for pumping, thus saving costs.

Preferably, the system includes a heat pump system adapted to take heat from the hot transfer water of the heat transfer line and adapted to transfer heat to the distribution piping at a higher temperature. In other words, the heat pump system is preferably adapted to take heat from its transmission line with its evaporator and to transfer heat with its condenser to the distribution piping. In this way, the temperature of the district heating water in the flow line can be kept lower than normal, whereby the heat loss of the district heating transfer is lower. In this case, the invention can also be used in connection with power plants whose condensate water is too cold for use in conventional district heating systems. In this context, a heat pump system means an assembly of one or more cascaded heat pumps, each heat pump comprising a compressor, a choke, an evaporator and a condenser. Preferably, the system includes a heat pump system adapted to heat the transmission water of the transmission line. In this way, the temperature of the transmission water in the transmission line can be raised to the required level, and plants that would not otherwise have sufficient heat production for district heating can also be used for district heating production. O 25 ro Preferably, the plant is also connected to the water system by a condensate drain line N and the heat pump system is adapted to take = heat from its condenser drain line and transfer heat to the transfer line with its condenser. In this way, the heat from the condensate water of the O 30 plant can be efficiently utilized for the production of N district heat.

N Preferably, the heat pump system is connected to at least one side (evaporator or condenser side) of its so-called circuit.

with a robbery / condenser side pump to circulate the medium from the common line.

In this case, the operation of the system easily adapts to various disturbance and change events. Preferably, the heat pump system is further connected on the evaporator side to use water as a heat source.

In this way, the water taken from the water body can be cooled in the summer before the water is delivered to the plant and the heat from the water body can be used to produce district heating.

In addition, the system also includes a hot tub fitted between the district heating transmission line and the district heating distribution pipeline supply line.

In this case, hot transfer water can be stored when heat production is advantageous.

In addition, the system also includes a cold pool arranged between the return line of the district heating distribution pipeline and the water system.

In this case, the stored cold water can be used flexibly for cooling.

In addition, the system also includes district cooling piping for transferring heat from heat consumers to the cold pool.

In this way, cooling of customer properties can be provided, which O 25 can also be needed at the same time as heating, for example due to internal heat sources in buildings, such as N machines, computers and other electrical equipment. = a ~~ The distance between the plant and the heat consumers can be 5 to 100 km, preferably 30 to 100 km.

In this case, the energy and cost savings achieved by the district heating N transfer according to the invention are very significant.

Preferably, the distance between the discharge end of the exhaust pipe and the inlet of the inlet line of the plant is 50 to 100%, preferably 80 to 100%, of the distance between the plant and the heat consumers. In this case, the transfer water is discharged into the water body close to the heat consumers, whereby the number of pipes is considerably smaller compared to the known technology. Preferably, the system comprises a flue gas scrubber adapted to preheat the water taken from the water and a boiler adapted to heat the water taken from the water. In this way, the heat generated by the plant can be efficiently transferred to the water. Preferably, the system includes a heat exchanger for transferring heat from the transmission line to the district heating distribution pipeline and a heat pump system adapted to heat the return of district heat alongside the heat exchanger. In this way, the heat of the transmission line can be efficiently transferred to the closed circuit of the district heating distribution piping.

Preferably, the system is connected to the water supply network so that the cooled water of the transmission line is led to a water utility. In this way, water taken from the watercourse and used to transfer district heat can be recycled to the water supply network before the O 25 water is returned to the watercourse. 8 N In the method according to the invention, district heat transfer = produces heat in a plant connected to the water supply line N and transfers heat to the O 30 transmission water taken from the water body, supplies heat to a large number of heat consumers, supplies heat to the district heating system, is transferred from the plant to the heat consumers in the hot transfer water transmission line, and in the flow direction of the hot transfer water at the beginning of the transmission line the heat is transferred to the transmission water plant, and at the end of the transmission line the heat is transferred from the transmission line to the distribution pipeline.

Heat is transferred from the plant to heat consumers in a one-way insulated hot water transfer line without a return pipe, the transfer water is discharged from an outlet pipe with a% discharge end closer to the end of the between the discharge end of the circulation outlet pipe and the inlet end of the plant inlet line.

In this way, district heating can be transferred from the plant to heat consumers with less piping and lower network losses and thus lower total costs and energy.

The invention will now be described in detail with reference to the accompanying drawings, which illustrate some embodiments of the invention, in which Figure 1 shows a system according to the invention for district heat transfer, Figure 2 shows another system according to the invention for district heat transfer. 8 N In one district heat = transfer according to the invention shown in Figure 1, the hot transfer water passes between the heat generating plant 32 N and the heat consumers 18 O 30 away from the plant 32 in only one pipe, namely the transfer water transfer line N 50. The return line is instead water body 10, N is, for example, the sea that forms the open circuit of district heating.

The plant 32 may be any heat generating plant 32 connected to the water body 10 by an inlet line 321 and a condensate outlet line 326. The plant 32 at the beginning of the transmission line 50 may be, for example, a power plant in Porvoo and heat consumers near the end 59 of the transmission line 50 may be located in Helsinki, in which case the distance L between them is approximately 40 km.

Plant 32 may also be, for example, a nuclear power plant in Loviisa.

From the water body 10 the water is led to the plant 32 in the supply line 321. From the plant 32 the hot condensate is first fed to the pipe 322, from where the hot water is led through the three-way valve 324 to the condensate drain line 326 and the district heating transfer line 50. The heat pump system 40 may comprise a single heat pump or a plurality of cascaded heat pumps.

The heat pump system 40 is adapted to take heat from the condensate discharge line 326 by its evaporator and to transfer heat by its condenser to the district heat transfer line 50, to which the heat pump system 40 is also preferably connected by an open circuit via pipes 401 and 402.

In this case, a recurring rise in the temperature of the district heating flow is achieved.

The water produced by the plant 32 in the pipe 322 may have a temperature of, for example, 25 to 35 ° C, and the water heated by the heat pump system 40 in the district heating transmission line 50 is preferably 55 ° C.

As a result, the water in the condensate drain 326 cools to about 10 ° C and the cooled water is returned to the water 10. N Cooling the water in the condensate 326 with the heat pump system 40 also reduces the N heat load caused by the condensate to the water 10. O 30 3 In addition to the heat pump 40 preferably connected on its evaporator side to the inlet line 321 via pipes 327 and 328.

In this case, the heat pump system 40 can also use the water body 10 directly as a heat source, preferably in summer, when the water system 10 is warm, and thus cools the water in the supply line 321. From the district heating transmission line 50, the district heating water is led to the heating pool 601. The heating pool 601 can act as a battery that is charged when the hot water output is favorable and discharged when the hot water output is expensive. The system also includes a cold pool 602 to which district heating water is conducted from the hot tub 601 in the tube 604. A heat pump system 60 is connected to the tube 604 by a robbery connection. The temperature of the water from the hot tub 601 is preferably about 55 ° C and the heat pump system 60 preferably cools the water to a temperature of 10 to 15 ° C. The heat pump system 60 is connected from the condenser side by a robbery connection to a pipe 606 which connects to the manifold 24. The manifold 24 supplies hot water to the heat consumers 18 on the supply line 28. The cooled water from the heat consumers 18 returns to the heat pump system 60 in the return line 30. O 25 The system further includes a district cooling piping 29 with which cold water can be supplied to the ro heat consumers 18 from the cold pool 602 for cooling. Heating and cooling can = be arranged simultaneously. The temperature of the cold cooling water is preferably 10 to 15 ° C. O 30

LO N The open-circuit district heating water is led from the cold pool 602 N back to the water system 10 in the discharge pipe 603. The water can also be used as hot water after the transfer of the district heat, whereby the water returns to the water system 10 at the end of the hot water cycle.

Between the discharge end 613 of the discharge pipe 603 and the inlet end 331 of the supply line 321 of the plant 32, the natural water circulation, in this case the water body 10, acts as a return circuit. The invention also relates to a district heating system in which heat production takes place far from consumption, where a power plant cannot be set up economically. This is the case, for example, in Helsinki. A power plant using biofuel would be uneconomical in Helsinki, as biofuel (logging residues, etc.) would have to be brought from far away in the middle of densely populated areas. The transport of ash must also be taken into account.

Figure 2 shows a system that solves the above problem. the plant 32, preferably a biofuel power plant, is located in a logistically advantageous location for fuel deliveries and close to a water body 10 from which water for heat transfer is obtained. In Figure 2, water is taken from the water body 10 (lake or river), which is preferably cooled in summer by a heat pump system -70, whereby the flue gas scrubber 34 of the plant 32 always reaches a low final flue gas temperature and heats up before it is delivered to boiler 36. is 120 - 75 ° C depending on the season. = a ~~ Boiler 36 may have steam generation. Figure 2 shows a cylinder 361, an O 30 circulating water pump 362 and a superheater 363 for supplying steam to an N turbine (not shown). Alternatively, it is a boiler, in which case there is no electricity production at all.

The boiler 36 thus discharges water, which is preferably water from the area, to be heated by a single pipe arrangement in a transmission line 50 to a district heating site 18. The district heating water circulates in a closed circuit in the distribution pipe 24. In the district heating distribution pump 51 Alongside the district heating heat exchanger 51, which transfers heat from the actual transmission line 50 to the supply line 28, there is a condenser 81 of the heat pump system 80 which heats the district heating return water, a smaller side stream which is connected to the main stream for pumping along the mains. In the heat exchanger 51 and the evaporator 82 of the heat pump system 80, the cooled water in the transfer line 50 can be passed to the water plant 90.

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Claims (15)

PATENT CLAIMS A system for district heat transfer, the system comprising - a at least one heat generating plant (32) connected to a water body (10) by an inlet line (321) having an intake head (331) and adapted to transfer heat to a water body (10) - a large number of heat consumers (18), - a district heating distribution pipeline (24) for conducting heat to the district heat consumers (18), and - a hot transfer water transmission line (50) for transferring heat from the plant (32) to the heat consumers (18), where the plant (32) is in the flow direction of the hot transfer water at the beginning (58) of the transfer line (50) and at the end (59) of the transfer line (50) is means for transferring heat from the transfer line (50) to the distribution pipeline (24), characterized in that - the hot transfer water transfer line (50) without a return pipe, the system comprises an outlet pipe (603) for discharging the transfer water into a body of water (10), the discharge end (613) of the outlet pipe (603) being closer to the end (59) of the transfer line (50). the starting end of the float - (58), and O 25 - as the return line of the transfer water from the outlet pipe (603) to the inlet line (321) of the plant (32) is adapted to operate a natural water circulation, N preferably a water body (10), forming an open circuit 613) and the input end (331) of the input line N (321) of the plant (32). O 30 N A system according to claim 1, characterized in that the system comprises a heat pump system (60) adapted to take the heat transfer line (50) from the hot transfer water and adapted to transfer heat to the distribution piping (24) at a higher temperature. A system according to claim 1 or 2, characterized in that the system comprises a heat pump system (40) adapted to heat the transfer water of said transmission line (50). A system according to any one of claims 3, characterized in that the plant (32) is also connected to the water body (10) by a condensate drain line (326) and that the heat pump system (40) is adapted to take heat from said condensate drain line (326) and dissipate heat to said transmission line (50). System according to one of Claims 3 to 4, characterized in that the heat pump system (40) is connected to its circulation circuit at least on one side (evaporator or condenser side). with a robbery / condenser side pump to circulate the medium from the common line. System according to one of Claims 3 to 5, characterized in that the heat pump system (40) is further connected on its evaporator side to use the water body (10) as a heat source. N = System according to one of Claims 1 to 6, characterized in that the system further comprises a heating basin O 30 (601) arranged between the transmission line (50) and the supply line (28) of the district heating distribution pipeline N (24). OF A system according to any one of claims 1 to 7, characterized in that the system further comprises a cold pool (602) fitted between the return line (30) of the district heating distribution pipeline (24) and the water body (10). A system according to any one of claims 1 to 8, characterized in that the system further comprises a district cooling piping (29) for transferring heat from heat consumers to said cold pool (602). System according to one of Claims 1 to 9, characterized in that the distance (L) between the plant (32) and the heat consumers (18) is 5 to 100 km, preferably 30 to 100 km. System according to one of Claims 1 to 10, characterized in that the distance between the discharge end (613) of the outlet pipe (603) and the inlet end (331) of the inlet line (321) of the plant (32) is 50 to 100%, preferably 80 to 100%, of the plant (32) and heat consumers (18). A system according to any one of claims 1 to 11, characterized in that the system comprises a flue gas scrubber (34) adapted to preheat the water taken from the water body (10) and a boiler (36) adapted to heat the water taken from the water body (10). O 25 A system according to any one of claims 1 to 12, characterized in that the system comprises a heat exchanger (51) for transferring N heat from the transmission line (50) to the district heating distribution piping (24) and a heat pump system (80) adapted N to heat the district heat return to the heat exchanger. (51) alongside. O 30 N System according to one of Claims 1 to 13, characterized in that the system is connected to the water supply network in such a way that the cooled water of the transmission line (50) is led to the water plant (90). A method for the transfer of district heat, comprising: - producing heat in a plant (32) connected to a water body (10) by an inlet line (321) and transferring heat to a transfer water taken from the water body (10), - supplying heat to a plurality of heat consumers (18), is supplied to the district heat consumers (18) in the district heating distribution pipeline (24), and - heat is transferred from the plant (32) to the heat consumers (18) in the hot transfer water transmission line (50), and in the hot transfer water upstream (58) (32), and at the end (59) of the transmission line (50) heat is transferred from the transmission line (50) to the distribution pipeline (24), characterized in that - heat is transferred from the plant (32) to heat consumers (18) in a one-way insulated hot water transmission line (50) ) without a return pipe, - the transfer water is discharged into the water body (10) from an outlet pipe (603) whose discharge end (613) of the outlet pipe (603) is closer to the transfer line (5). 0) an end (59) rather than an initial end (58), and - the transfer water is returned from the outlet pipe (603) to the inlet line (321) of the plant (32) via a natural water circulation, preferably a water body - (10), forming an open circuit outlet pipe for district heating N S 25 (603) between the discharge end (613) and the inlet line 3 (331) of the input line (321) of the plant (32). 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