DE8703599U1 - Device for steam extraction and drainage from steam pipelines with simultaneous heat transfer to heat consumers, preferably as a house station (heat transfer station) of steam district heating systems - Google Patents

Description

Dr.-Ing. Franz MaIy Ostfildern, 9.3.1987

Mühlhaldenstrasse 6/1

D - 7502 Ostfildern 2 (Nellingen)

Apparatus for steam extraction and drainage from steam pipelines with simultaneous heat transfer to heat consumers, preferably as a house station for steam district heating systems.

Object

The subject of the invention is an apparatus which simultaneously for

a) Steam extraction from a steam pipeline for heating purposes (or for other heat consumption),

b) Drainage of the steam pipeline, and

c) Heat transfer to the heat consumer using the heat content of the line condensate and the condensate of the heat consumer

serves,

and also ensures that the laying of steam pipelines (steam supply lines) is simplified and cheaper and that the construction of the supply network is largely independent of the terrain.

In the current design of steam district heating systems, the condensate from the heat consumer is returned to the heating plant in the so-called condensate line. This condensate is usually subcooled, i.e. its temperature is lower than the saturation temperature associated with the prevailing pressure.

In addition to this condensate, the so-called line condensate (also: "remote condensate") also occurs in the steam mains: part of the flowing steam condenses due to the heat losses in the line. Steam lines must therefore be constantly drained if they are in operation.

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For this purpose, they are laid with a gradient and equipped with drainage devices at the lowest points (water trap on the steam line, connections, shut-off device, steam line, automatic condensate drain, check valve, connection to the condensate line, if necessary other shut-off devices or measuring devices). These devices are usually installed in buildings because they require permanent monitoring.

The line condensate is either returned to the heating plant in a separate "line condensate line" or fed into the condensate line at certain points. In this case, the installation of so-called condensate coolers is required to cool the line condensate beforehand.

In any case, the handling of condensate as it is known and practiced today requires structures and facilities in the supply network with constant monitoring, maintenance and repair. This involves considerable investment. It also makes practical operational management more difficult.

A steam supply system is therefore desirable in which

1. the steam pipes can be laid with any gradient and thus within certain limits without taking the terrain into account.

. can be laid and operated,

2. all facilities for draining the steam pipes j

can be omitted, I

3. all condensates occur at a common temperature, j

This temperature should ideally be between 30 and 40 ^° C.

A low condensate temperature should always be aimed for so that the condensate heat is utilized as much as possible and the heat losses in the condensate lines are reduced.

When operating with "lost condensate", i.e. when the condensate is not returned to the heating plant but drained into the sewer system, a condensate temperature of approx. 35 ⁰ C must be maintained.

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This last-mentioned mode of operation is particularly economical, since all equipment such as pumps, pipes, structures, etc., which are otherwise required for condensate recovery, are eliminated, and the steam supply network can be constructed as a single-pipe system, similar to a gas supply.

This is achieved with the apparatus described below ■" according to the invention in that the heat is not transferred to the heat consumer by condensing the steam in a condenser, but by the steam and the line condensate being taken from the steam pipeline via a common line and fed to a mixing vessel in which they are mixed with the water of a primary circuit and then fed as a ("directly") heated liquid to a heat exchanger, the secondary circuit of which is the building heating.

•The circulation pump installed in the primary circuit serves to maintain the heat transfer in the heat exchanger and the mixing process in the mixing vessel. It also removes a quantity of cooled water from the primary circuit corresponding to the amount of steam and line condensate supplied and conveys it into the condensate line or into the sewer system. This is done via a temperature-controlled control or outlet valve.

The mixing vessel, the heat exchanger, the primary pump, the control valve and the connecting lines together form a functional unit, i.e. the apparatus according to the invention. |

In principle, the device is suitable for supplying heat consumers of all kinds, as long as the temperature level of the steam supply corresponds to the requirements of the heat consumer. However, it is primarily used to simplify and reduce the cost of steam district heating for supplying individual buildings or settlements.

In the following description of the functionality, it is therefore assumed that the device is used as a house station (heat transfer station) for a steam district heating system, j where the performance of the building heating system depends on the climatic

see conditions in Central Europe (about 50 degrees latitude). The numerical values given in the text are only examples and were chosen freely within this framework.

Description of how it works

Fig. 1 shows the apparatus for operation with lost condensate.

When the system is ready for operation (no heat demand) only the steam main (5) and the primary pump (2) are in operation. The steam main keeps the primary circuit, consisting of the mixing vessel (1), the primary pump (2), the heat exchanger (3) and the connecting line (4), under pressure, whereby the house connection line (6) is gradually filled with line condensate. A small amount of primary water flows temporarily into the sewer system (13) via the temperature-controlled control valve (9) when the temperature of the primary circuit falls below a set value tj. (e.g. t _E = 50 ⁰ C). This value is set on the sensor of the control valve (10).

The heat requirement is met by the secondary pump (17) starting up. Due to the heat transfer in the heat exchanger (3), the temperature of the primary water after the heat exchanger falls below t-g. This causes the control valve (9) to be opened further for a longer period of time and correspondingly more of the cooled primary water is removed from the primary circuit. This means that more steam is fed into the primary circuit until the temperature at the sensor (10) reaches the set value γ-, again.

The heat exchanger (3) and the building's radiators (16) are dimensioned so that when the control valve (9) is opened to its maximum, a quantity of steam can flow into the primary circuit, which ensures the desired flow temperature for the building's heating.

Before the primary water at temperature tp can flow out via the control valve, it is led through the aftercooler (12) where it is cooled to the discharge temperature.

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If the building to be heated is a single-family home, the aftercooler can consist of, among other things, a commercially available sectional heating box, which is installed in a subordinate room of the building, preferably facing north.

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With an inlet temperature of t-, = 50 ⁰ C, an outlet temperature between 30 and 40 ⁰ C can be reliably achieved in all seasons. However, other designs of the aftercooler are also conceivable, e.g. in connection with hot water preparation, etc.

Fig. 2 shows a further variant of the apparatus according to the invention.

In this case, the primary water to be drained is pumped into a condensate line (19) at the temperature t~ and thus recovered.

From the illustration in Figure 2, it is immediately apparent that the choice of the discharge head of the primary pump (2) means that the course of the condensate line (19) is independent of the terrain. To indicate this, the condensate line (19) in Figure 2 has been drawn slightly higher than the steam pipeline (5).

Since the house connection pipes (6) are usually arranged every 20 to 50 m along the steam pipeline (5), the steam pipeline is drained at these intervals when the device according to the invention is used. The steam pipeline can therefore be laid horizontally or at (almost) any angle. For comparison: normally drainage points are installed on a steam pipeline every 100 to 300 m*

&Idigr; The steam flowing over the condensate follows the laws

Moderation of the gas flows, which are - at least in this context - largely independent of the height of the pipes.

J For these reasons, the supply network can be laid largely without consideration of the terrain.

Fig. 3 shows a further variant of the apparatus according to the invention.

In this case, the cooled primary water is fed into the condensate line (19) optionally via an aftercooler (12) in the outlet line (11).

Fig. 4 shows a further variant of the apparatus according to the invention.

In this case, the control valve (9) is controlled via a controller (20) with setpoint adjustment (21) and inclusion of the building flow temperature (22) and the outside temperature (23).

The other designations in Fig. 1 to 4 are:

(7) Shut-off devices

(8) Check valves

(14) Supply line of the building heating

(15) Return line of the building heating system (18) Expansion vessel of the building system·

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Claims (5)

Dr. Ing. F. MaIy Ostfildern, 21 May 1987 Protection claims 1. Device for steam extraction and drainage from steam/long-distance pipelines with simultaneous heat transfer to heat consumers, preferably as a house station (heat transfer station) of steam district heating systems, characterized in that it has a primary circuit with a mixing vessel (1), a circulation pump (2) and a heat exchanger (3), in which primary circuit the primary water is constantly circulated during operation. J 2. Device according to claim 1, characterized in that it is connected to the steam supply line (5) via a single connection line (6) which serves both for removing steam from the supply line (5) and for draining the supply line (5), and thus generally supplies a mixture of steam and line condensate to the device. 3. Device according to claim 2, characterized in that the mixing vessel (1) for mixing the mixture of steam and line supplied via the connecting line (6) x __ condensate is formed with the constantly circulating water of the primary circuit. 4. Device according to one of claims 1-3, characterized in that a - preferably temperature-controlled - drain device (7, 9, 11, 12, 13) for cooled primary water is provided on the outlet side of the heat exchanger (3). 5. Device according to claim 4, characterized in that the discharge device has an aftercooler (12).