GB2076524A

GB2076524A - District Heating

Info

Publication number: GB2076524A
Application number: GB8017077A
Authority: GB
Original assignee: BELL GEORGE MALCOLM
Current assignee: BELL GEORGE MALCOLM
Priority date: 1980-05-23
Filing date: 1980-05-23
Publication date: 1981-12-02
Also published as: GB2076524B

Abstract

A district heating system is disclosed in which a single main distribution pipe 12 is taken from a source of hot water 10, e.g. waste water from a power station, to the buildings to be heated. After passing through radiators 16 and hot water cylinders 18, the now spent hot water is discharged to drain. In a modification, the spent hot water is drained into a storage tank and used to supply the "cold taps" of baths or washbasins, or to supply water closets or hot water cylinders. <IMAGE>

Description

SPECIFICATION District Heating This invention relates to a district heating system, and in particular to a single pipe district heating system.

Power stations, and certain other types of large industrial processes, produce large quantities of hot water as a by-product. This hot water represents a waste product since the power station must dispose of it, and often it is merely cooled and dumped into a river. With rapidly rising energy costs the energy wastage represented by such practices is causing increasing concern, and schemes for using the waste hot water for heating nearby homes, offices or factories and the like are being proposed. The use of a centralised source of hot water piped to nearby buildings is known as "district heating".

Currently ploposed systems of district heating have not, however, met with a great deal of success since in many cases the capital cost of installing the necessary flow and return pipework, together with the maintenance thereof, has outweighed the cost of savings in using an effectively "free" supply of hot water.

The invention seeks to provide a district heating system of lower capital costs and having lower maintenance costs than systems hitherto proposed.

According to the present invention there is provided a district heating system in which a single main distribution pipe is taken from the source of hot water to the buildings to be heated and in which the hot water, once it has passed th ough an individual build ng, is dischargd to drain.

The use of a single pipe system, rather than a return and flow system, means that only half the pipework is required to distribute the hot water to the buildings to be served. The hot water may be distributed under high pressure and so the diameter of pipe needed may be kept to a minimum.

The pipework used may be constructed of any of the conventional water-piping material, for example steel, copper or certain plastics materials. However, in general copper piping is preferred for its resistance to corrosion and low cost of maintenance. Once the water has been piped to, and used in, an individual building, it may be discharged to drain, preferabiy through a thermostatically controlled limit valve which will only discharge the water when it is below a certain temperature. Alternatively, instead of discharging it to drain, if the water originally has come from a relatively "clean" supply for example a town main supply, the used hot water may be discharged to a tank and used to supply, for example, washbasins, hot water cylinders, water closets, and the like.

The source of waste water, particularly from a power station, can be of two main varieties. First a high temperature supply, having a superatmospheric pressure at temperatures in the order of 3500F, or a low temperature supply typically having a temperature in the order of 1800 F. While the system of the invention may be adapted to be used with either supply it is preferred for it to employ high temperature waste water supply. A high temperature supply may be modulated, that is reduced in temperature, by various means at the power station, and in certain circumstances, for example, during the summer months, it may be desirable to use the modulated supply rather than the full high temperature supply.

The invention will be described further, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a block diagram of a single pipe district heating system according to the invention; and Figure 2 is a block diagram of a modified form of the system of the invention.

Referring to Figure 1, waste hot water from a power station boiler heat exchanger 10 is piped along a single main distribution pipe 12 to various buildings in the locality of the power station. A branch distribution pipe 14 serves an individual building and the hot water may pass through one or more radiators, convectors, heat exchanges, or the like, diagrammatically illustrated at 1 6 in Figure 1, for space heating. From the radiator 1 6 the water may pass to the heating coil of an indirect hot water cylinder 1 8 to heat the building water supply. From the indirect cylinder 1 8 the, now spent, hot water passes through a thermostatically controlled limit valve 20 to drain.

In Figure 2, the water from the heat source 10 passes through a main distribution pipe 12 and each building has a branch distribution pipe 14.

After passing through radiator 1 6 and the indirect cylinder 18, the water is now piped to a storage tank 22. From the storage tank 22 the water, which is now lukewarm, may be used to supply the "cold" taps on washbasins 24, or baths 26.

The water may also be used to supply water closets 28 and may be fed back to the hot water cylinder to act as the hot water supply. This latter has the added advantage that since the water supplied to the cylinder 1 8 may still have a residual temperature in the order of 1 00 F it requires less energy to heat it up to the required hot water temperature for domestic consumption, namely in the region of 1 40 C.

It can be seen that the system of the invention provides a simple and economical means of district heating which has a relatively low capital cost to install and requires only mimimal maintenance. Although the supply of hot water may be under fairly high pressure, the normal plumbing employed in domestic hot water and central heating systems, namely soldered copper piping, is perfectly adequate to cope with the increased pressure and so it is envisaged that no modification to the domestic installations would be necessary.

Claims

1. A district heating system in which a single main distribution pipe is taken from a source of

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION District Heating This invention relates to a district heating system, and in particular to a single pipe district heating system. Power stations, and certain other types of large industrial processes, produce large quantities of hot water as a by-product. This hot water represents a waste product since the power station must dispose of it, and often it is merely cooled and dumped into a river. With rapidly rising energy costs the energy wastage represented by such practices is causing increasing concern, and schemes for using the waste hot water for heating nearby homes, offices or factories and the like are being proposed. The use of a centralised source of hot water piped to nearby buildings is known as "district heating". Currently ploposed systems of district heating have not, however, met with a great deal of success since in many cases the capital cost of installing the necessary flow and return pipework, together with the maintenance thereof, has outweighed the cost of savings in using an effectively "free" supply of hot water. The invention seeks to provide a district heating system of lower capital costs and having lower maintenance costs than systems hitherto proposed. According to the present invention there is provided a district heating system in which a single main distribution pipe is taken from the source of hot water to the buildings to be heated and in which the hot water, once it has passed th ough an individual build ng, is dischargd to drain. The use of a single pipe system, rather than a return and flow system, means that only half the pipework is required to distribute the hot water to the buildings to be served. The hot water may be distributed under high pressure and so the diameter of pipe needed may be kept to a minimum. The pipework used may be constructed of any of the conventional water-piping material, for example steel, copper or certain plastics materials. However, in general copper piping is preferred for its resistance to corrosion and low cost of maintenance. Once the water has been piped to, and used in, an individual building, it may be discharged to drain, preferabiy through a thermostatically controlled limit valve which will only discharge the water when it is below a certain temperature. Alternatively, instead of discharging it to drain, if the water originally has come from a relatively "clean" supply for example a town main supply, the used hot water may be discharged to a tank and used to supply, for example, washbasins, hot water cylinders, water closets, and the like. The source of waste water, particularly from a power station, can be of two main varieties. First a high temperature supply, having a superatmospheric pressure at temperatures in the order of 3500F, or a low temperature supply typically having a temperature in the order of 1800 F. While the system of the invention may be adapted to be used with either supply it is preferred for it to employ high temperature waste water supply. A high temperature supply may be modulated, that is reduced in temperature, by various means at the power station, and in certain circumstances, for example, during the summer months, it may be desirable to use the modulated supply rather than the full high temperature supply. The invention will be described further, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a block diagram of a single pipe district heating system according to the invention; and Figure 2 is a block diagram of a modified form of the system of the invention. Referring to Figure 1, waste hot water from a power station boiler heat exchanger 10 is piped along a single main distribution pipe 12 to various buildings in the locality of the power station. A branch distribution pipe 14 serves an individual building and the hot water may pass through one or more radiators, convectors, heat exchanges, or the like, diagrammatically illustrated at 1 6 in Figure 1, for space heating. From the radiator 1 6 the water may pass to the heating coil of an indirect hot water cylinder 1 8 to heat the building water supply. From the indirect cylinder 1 8 the, now spent, hot water passes through a thermostatically controlled limit valve 20 to drain. In Figure 2, the water from the heat source 10 passes through a main distribution pipe 12 and each building has a branch distribution pipe 14. After passing through radiator 1 6 and the indirect cylinder 18, the water is now piped to a storage tank 22. From the storage tank 22 the water, which is now lukewarm, may be used to supply the "cold" taps on washbasins 24, or baths 26. The water may also be used to supply water closets 28 and may be fed back to the hot water cylinder to act as the hot water supply. This latter has the added advantage that since the water supplied to the cylinder 1 8 may still have a residual temperature in the order of 1 00 F it requires less energy to heat it up to the required hot water temperature for domestic consumption, namely in the region of 1 40 C. It can be seen that the system of the invention provides a simple and economical means of district heating which has a relatively low capital cost to install and requires only mimimal maintenance. Although the supply of hot water may be under fairly high pressure, the normal plumbing employed in domestic hot water and central heating systems, namely soldered copper piping, is perfectly adequate to cope with the increased pressure and so it is envisaged that no modification to the domestic installations would be necessary. Claims

1. A district heating system in which a single main distribution pipe is taken from a source of hot water to the buildings to be heated and in which the hot water, once it has passed through an individual building, is discharged to drain.

2. A system as claimed in claim 1 in which the single main distribution pipe is a copper pipe.

3. A system as claimed in either of claims 1 and 2 in which the used hot water is discharged through a thermostatically controlled limit valve.

4. A system as claimed in either of claims 1 or 2 in which the used hot water is discharged to a storage tank from which it supplies washbasins, baths, water closets or hot water cylinder.

5. A system as claimed in any of claims 1 to 4 in which the source of hot water is under pressure and at temperature in the order of 3500 F.

6. A district heating system substantially as herein described with reference to and as illustrated in Figure 1 or Figure 2 of the accompanying drawings.