DE1244366B - Electrically heated liquid steam generator equipped with a heat storage device - Google Patents

Description

Provided with a heat storage device, electrically heated Liquid vapor generator The invention relates to one with a heat storage device equipped, electrically heated liquid steam generator, in which the heat storage its heat by evaporation and condensation of a liquid in a heat exchanger to the final heat transfer medium to be heated.

A liquid steam generator of this type is already known at which is a vertically arranged, loosely filled with thermally conductive material, Kettle covered by a jacket made of heat-retaining fabric. Water from above is fed forth. Between the boiler and the jacket made of heat-retaining fabric an expandable, highly thermally conductive layer is provided in which the electrical Radiators are embedded, through which the heat storage z. B. with cheap night electricity can be heated. This liquid steam generator can be used in conjunction with a hot water heating system can be used when the generated water vapor its heat via a heat exchanger to a through the hot water heating system releases circulating amount of water, the water vapor after releasing its heat and after condensation in the circuit returned to the storage tank for evaporation can be. The inflow of the water to be evaporated into the boiler is either depending on the water vapor pressure in the boiler or the temperature of the heating water controlled by a regulator. In this known system there is once the regulation the amount of water to be evaporated fed to the boiler, especially when starting up the system, difficult, on the other hand, the water entering the boiler evaporates immediately, and the steam pressure in the boiler and in the steam line rises suddenly at. Therefore, the water supply to the boiler is shut off by the control valve. To If the steam pressure in the boiler falls, the valve opens again and the process is repeated themselves. These strong fluctuations or the oscillation of the pressure in the boiler are for the operation of the boiler unfavorably and not completely prevent with the known means. On the other hand, in this system, the one between the boiler and the actual one Heat storage jacket provided layer made of thermally conductive material due to the movements of the boiler and tries to blow up the heat storage jacket.

To remedy that, one is using a heat storage device provided, electrically heated liquid steam generator of the aforementioned Kind according to the invention of the evaporator at its lowest point via an expansion line with an expansion vessel with at least the same volume as the evaporator connected, at the junction of the expansion line one of a throttle device Non-return valve that can be bridged and shuts off the backflow of the condensate into the evaporator is provided while in the expansion line between the evaporator and the Check valve and the throttle device switched on a steam separator is.

In a further embodiment of the invention, the expansion vessel be provided in the outlet line of the final heat transfer medium on the condenser, so that the expansion line from the evaporator with check valve and throttle device can be connected to the outlet pipe of the final heat transfer medium.

According to a further feature of the invention, the evaporator and the condenser can be connected to one another by a pipe. Instead of this the evaporator can also be connected to a steam line and a condensate return line be connected to the condenser, with the vapor separator in the condensate return line is switched on.

If several evaporators are used, these can be used in a further refinement the invention connected in parallel via a common steam manifold and a common condensate return line are connected to the condenser, whereby in addition, the steam collecting line can be connected to the expansion line.

The evaporator can also according to a further feature of the invention on the steam outlet side in parallel via individual steam lines into the steam collecting line open and each via a further connecting line to the condensate inlet end of the next vaporizer and only the first vaporizer directly are in connection with the condensate return line.

According to the invention, when several evaporators are used, each evaporator have a steam line to the condenser and on its condensate inlet side discharge into the common condensate return line in parallel.

Some embodiments of the invention are given below described by drawings. F i g. 1 is a vertical longitudinal section by an embodiment of the liquid steam generator according to the invention an expansion tank and a single connection line between an evaporator and a capacitor, FIG. 2 shows a vertical longitudinal section through another Embodiment in which the expansion line with an outlet line of a final heat transfer medium connected, F i g. 3 shows a vertical longitudinal section through an embodiment with separate steam line from the evaporator to the condenser and condensate return line from the condenser to the evaporator, FIG. 4 and S different configurations of the Steam line inlet into the condensation chamber of the condenser and the condensate return line outlet from the condensation space in the embodiment according to FIG. 3, fig. 6 one vertical longitudinal section through the condenser and evaporator part of another Embodiment of the liquid vapor generator according to the invention, with several Evaporator and heat storage cores are provided, F i g. 7 is a vertical longitudinal section by an embodiment which is similar to that of FIG. 6, apart from that the evaporator and the heat storage cores are inclined and the steam manifold is connected to the expansion line, F i g. ß and 9 each have a vertical Longitudinal section of the evaporator and condenser part with further embodiments several inclined, superimposed evaporators and heat storage cores, F i g. 10 shows a vertical longitudinal section through an embodiment with condensation the heat transferring substance in the evaporator and control valve in the bypass line, F i g. 11 the additional arrangement of two control or shut-off valves in the condensation line from F i g. 10, fig. 12 also shows a vertical longitudinal section through an embodiment with condensation of the heat transferring substance in the evaporator, with additional the expansion line with the expansion tank is also shown, and the F i g. 13 and 14 a vertical longitudinal section through and the plan view of a Another embodiment of the liquid steam generator according to the invention with condensation of the heat-transferring substance to those not enclosed by heat accumulators and walls of the evaporator free of heat-insulating protective layers.

The individual figures are to be understood as schematic drawings.

According to FIG. 1, a heat accumulator 3 surrounded by a housing 1 and a heat insulating layer 2 is provided in the liquid steam generator, which heat accumulator 3 can be heated by means of an electrical heating device 4 embedded therein. In the heat accumulator 3, an evaporator 6 provided with a jacket 5 is inserted, embedded or formed by corresponding cavities in the heat accumulator. The evaporator 6 is connected by the line 7, 10 to the condensation space 8 of a condenser, the condensation surface 9 of which separates the condensation space from the heating space 11. The boiler room is connected via a boiler room inflow line 12 and a boiler room outflow line 13 to the line of the final heat transfer medium, for. B. with the return and flow lines of a hot water heating system. At its lowest point, the expansion line 14 opens into the evaporator 6 via a vapor separator 19, which at its other end is connected to the expansion vessel 17 via a check valve 16 , the volume of which is at least as large as that of the evaporator 6, the line 7, 10 and the condensation space B. The check valve 16 is bridged by a throttle device 15 connected in parallel, preferably by the capillary shown. In the evaporator 6, the expansion line 14 and the expansion vessel 17 there is a liquid which serves as a heat exchanger between the condensation surface 9 and the heat accumulator 3. The electrical heating device 4, which may consist of a heating coil, tubular heater or the like, is connected to the electrical network and, when switched on, heats the heat accumulator 3 to the desired temperature.

The way in which the system works is explained below. Due to its higher temperature, the heated heat accumulator 3 gives off heat to the liquid contained in the evaporator, in particular water, and evaporates it. The steam passes through the line 7, 10 into the condensation space 8, where it condenses on the condensation surface 9. The condensate flows back through the line 7, 10 into the evaporator 6 in order to evaporate again as long as and as far as the heat supply from the heat accumulator 3 is sufficient for the evaporation. The condensation on the condensation surface 9 takes place in accordance with the amount of heat absorbed by the final heat transfer medium flowing through the heating space 11. A reduction or interruption of the cooling of the condensation surface 9 by the final heat transfer medium reduces or interrupts the condensation of the heat transferring substance in the evaporator and thus also the evaporation or the removal of heat from the heat accumulator. The heat is thus transferred in a self-regulating manner depending on the heat extraction through the final heat transfer medium, the transfer limit being determined by the size of the cooling surface.

Before the electrical heating of the still cold heat storage tank begins 3 are the evaporator 6, the line 7, 10 and the condensation space 8 with the evaporative and condensable heat transfer agents, e.g. B. water filled. To when the electrical heater 4 is switched on, the temperature of the heat accumulator rises. 3 and consequently the evaporator jacket 5 until the transfer medium evaporates begins. The steam that forms pushes the heat transfer medium in the evaporator through the expansion line 14 into the expansion vessel 17, which, as an open vessel under atmospheric pressure, both above, next to or below the evaporator 6 can be arranged so that the evaporation with excess pressure, at atmospheric pressure or with a negative pressure corresponding to that which is established in each case in the expansion vessel 17 Water column takes place. If arranged accordingly, it will be well below the evaporator the evaporation point is reduced and thus the lower usable temperature limit of the heat storage improved. An arrangement of the expansion tank 17 over the The highest point of the rest of the system, on the other hand, makes it easier to use the usual means accomplishing venting. When condensation suddenly sets in and with it The throttle device prevents negative pressure arising in the condensation chamber 8 15, e.g. B. a capillary, needle valve, orifice plate. Ä. That too rapid after-flow and an associated excessive formation of steam of the heat-transferring substance, which could lead to local overpressure, pendulum of the transfer material column or the like, while the check valve 16 with interrupted condensation the heat transferring Means can flow unhindered into the expansion vessel 17, so that pressure increases can be prevented in the system. If the temperature of the heat storage tank gradually falls 3 and decaying heat supply to the evaporator jacket 5 fills the heat transferring Means more and more the evaporator 6 until no more evaporation takes place and the condensation space 8 is also filled with liquid heat transfer material. warmth is only through to the condensation surface 9 and thus to the final heat transfer medium Convection transferred, and the unit of evaporator 6 and condenser 8, 9, 11 acts as a simple heat exchanger.

When the final heat transfer medium can be evaporated and condensed and at the same time it is ensured that the final heat transfer medium is not necessary for the operation of the System assumes harmful overpressure, d. i.e. if z. B. in hot water collective heating systems a corresponding expansion vessel and / or other pressure regulator, possibly Safety valves or the like are provided, then a 'Peil of the final heat transfer medium branched off and fed into the evaporator, where it serves as a heat exchanger. According to FIG. 2, the expansion vessel 17 is omitted in this case; the one with the throttle device 15 and the non-return valve 116 provided expansion line 14 is via an expansion line 14a connected to the outlet line of the final heat transfer medium on the side of the condenser, on which the expansion vessel and / or another pressure regulator is in the line of the final heat transfer medium. For hot water heating systems z. B. the connection exists the expansion line 14 via the check valve 16 and the throttle device 15 and the expansion line 14a, preferably with the return line (in F i G. 2 this would correspond to the inflow line 12), since in the heating flow line Usually throttle or shut-off valves are installed.

The embodiment of the liquid vapor generator according to FIG. 3 differs compared to the according to FIG. 2 only in that a separate steam line 7 and condensate return line 10 a, 10 b is provided. The returning condensate passes through line 10 a into a vapor separator 19 and from there via the Line 10 b back into the evaporator 6. At the lowest point of the steam separator the expansion line 14 opens into this. The steam separator ensures, in particular when dividing the evaporator 6 into several units (Fig. 6 to 9), for this, that when the condensation from the evaporator 6 and the condensation space is interrupted 8 The steam-water mixture pressed out is initially separated into steam and water is, which prevents vapor bubbles in the expansion line 14 and the Expansion vessel 17 or are pressed into the final heat transfer medium when the expansion line 14 connected via the expansion line 14 a to the outlet line of the final heat transfer medium is.

With the separate arrangement of steam line 7 and condensate return line 10 or 10 a and 10 b , according to FIG. 3, the bottom of the condensation space 8 is inclined or according to FIG. 4, a weir 18 can be provided to raise the inlet opening of the steam line 7 into the condensation space 8, or according to FIG. 5 let the upper edge of the steam line 7 protrude a certain distance above the horizontal floor of the condensation space 8. Furthermore, it is also possible to incline the entire condenser 8, 9, 11 towards the condensate return line 10. By separating the steam line 7 and the condensate return line 10, it is possible, in contrast to the embodiments according to FIGS. 1 and 2, in which the condensate is fed to the evaporator 6 for renewed evaporation from above, this is fed to the evaporator 6 at any point, for example below, as shown in FIG. 3 is shown, whereby a better circulation in the conduction circuit of the heat-transfer medium is achieved in particular with pure heat exchanger operation, ie with heat transfer by convection. Depending on the task and other design of the entire system, one or the other evaporator charge may be more advantageous. So z. B. in the embodiments according to FIG. 1 and 2 saturated steam, while in the embodiment according to FIG. 3 superheated steam enters the condensation space 8.

In the embodiments according to FIG. .6 to 9 several evaporators 6, heat storage 3 and electrical heating devices 4 are provided. These units lie either horizontally or parallel to one another with a more or less large common inclination (FIGS. 7 to 9). The individual embodiments differ from one another in the design of the connection between the evaporator and the condensation space 8 of the condenser. In the embodiments according to FIG. 6 and 7, the condensate runs out of the condensation space 8 via a common condensate return line 10 and a condensate distributor 23 into the superposed evaporators 6, which are enclosed by the heat accumulators 3 with the electrical heating devices 4. On their steam outlet side, the evaporators 6 are connected in parallel via their respective steam line 7 to a steam collecting line 21, which has a correspondingly large diameter and opens into the condensation space 8 at the highest point. The condensate distributor 23 is connected to the expansion line 14. Likewise, the steam collecting line 21, as shown in FIG. 7, can be connected to the expansion line 14 via the connecting line 22. In the embodiment according to FIG. 8, the inclined, parallel superposed evaporators 6 are connected via their respective steam pipe 7 to the common steam collecting line 21 , which opens into the condensation space 8 in its higher part and can be connected to the expansion line 14, which is not shown. A connecting line 24 branches off from the steam line 7 of each evaporator 6 and runs to the condensate inlet end of the next evaporator, while only the first evaporator is connected to the condensate return line 10, which is connected to the expansion line 14. In the embodiment according to FIG. 9, each of the evaporators lying parallel one above the other has a separate steam line 7, from each of which a connecting line 24 is branched off, which runs to the condensate inlet end of the next evaporator 6 in each case. Again, only the first evaporator is connected to the condensate return line 10, which is connected to the expansion line 14. In addition to the in FIGS. 6 to 9, such a design of the liquid steam generator according to the invention is still possible in which, in the case of several evaporators, a separate steam line 7 and a common condensate return line 10 for all evaporators are provided for each evaporator 6, into which they open in parallel. The condensate return line 10 is connected to the expansion line 14 .

The types of installation shown in FIGS. 6 to 9 according to the Invention differ in terms of their effect in that in the embodiments according to FIG. 6 and 7 the evaporation can start in all evaporators at the same time. With a correspondingly large condensation surface 9, very large condensation surfaces can be used here for a short time Heat extraction rates are achieved, d. i.e., such a liquid evaporator is particularly suitable for burst operation. In the embodiments according to FIG. 8 and 9, the condensate is fed to the individual evaporators 6, starting from the bottom after another. Only when the initially charged evaporator 6 from the neighboring one Part of the heat accumulator 3 has dissipated so much heat that it deals with liquid Can fill transfer substance, this flows through the connecting line branched off at the top 24 in the next evaporator. The steam manifold 21 needs in this embodiment to have only a cross section in the size of the individual steam line 7, because theoretically only the amount of steam generated by an evaporator 6 to the condensation space 8 must be directed. The cross section of the steam manifold 21 is still something chosen larger, since also in an evaporator filled with liquid transfer substance 6 by continuing to supply heat from the lower parts of the heat accumulator 3 evaporation continues. The in F i g. 9 illustrated liquid evaporator works essentially like that in FIG. 8 shown.

According to the F i g. 10 and 12, the condenser can also be arranged within the evaporator 6 by namely a z. B. U-shaped or in the form of a helix bent pipe is arranged in the evaporator 6, which is connected through the thermal insulation layer 2 with the inlet line 12 and the outlet line 13. The evaporator is again connected via the expansion line 14, which is provided with a check valve 16 and a throttle device 15, either to an expansion tank 17 or to the side of the outlet line of the final heat transfer medium in which an expansion tank, a safety valve or the like is provided. In the case of the FIGS. In the embodiments of the liquid vapor generator shown in FIGS. 10 and 12, the heating space 11 and thus the condensation surface 9 are moved into the evaporator 6, which at the same time becomes the condensation space 8. This arrangement in particular eliminates the steam line 7 between the evaporator and the condensation chamber 8, the cross-section of which must be large to avoid high steam velocities ("whistling"), as well as the condensate return line 10. Since the final heat transfer medium located in the boiler room 1.1, ie in the curved line, should be interrupted for a long time the heat extraction is further heated and evaporated by the steam present on the condensation surface 9 in the evaporator, if it has a correspondingly low boiling point, the possibility of expansion of the final heat transfer medium by the steam generated in the heating room 11 must be given.

Regardless of the self-regulation of the condensation, the evaporation and the expansion in the liquid steam generator according to the invention, regulating or shut-off valves 20 can be used to regulate the heat extraction by the final heat transfer medium in the supply line 12 and / or in the outlet line 13 and / or between these two lines be arranged as in FIG. 10 and 11 is shown. These valves can be combined into a unit, for example a mixing valve, and mechanically or electrically connected to the other control devices of the circuit of the substance to be heated, e.g. B. the temperature controller of a hot water collective heating system, be coupled. By means of these valves 20, the expansion from the heating space 11 can be achieved with intermittent heat removal, e.g. B. by switching off a circulating pump arranged in a collective heating system, be directed into the inflow line 12 (heating return) or z. B. only part of the circulated final heat transfer medium, z. B. heating water, are passed through the boiler room 11, while the other part is passed parallel to this. The boiler room II can either be closed off on one side, which interrupts the heat transfer, or closed off on both sides if it has its own displacement space, with which the heat transfer can also be interrupted.

An arrangement of the condenser within the evaporator 6 is how in Figs. 10 and 12 is also possible if the liquid steam generator is equipped with several evaporators. In the F i g. 13 and 14 an embodiment of the liquid vapor generator is shown in which the Condensation of the heat transfer fluid on the not from the heat storage 3 enclosed wall parts of the evaporator 6 takes place. This is as a plate formed, the upper and lower surfaces of which each adjoins a heat accumulator 3 and which is connected to the expansion line 14, which - as in all embodiments of the liquid vapor generator - with a vapor separator, not shown, a check valve and a throttle device is provided. The heat storage 3 are surrounded by a thermal insulation layer 2. The boiler room 11 for the final heat transfer medium, which flows in at 12 and exits heated at 13, is a square ring box formed, the square, closed inner surface on the narrow sides of the Plate evaporator 6 and serves as a condensation surface 9. The plate evaporator 6 also serves as a condensation space B.

The embodiments according to FIGS. 6 to 9 can be divided into special advantageously also as a steam generator, e.g. B. for butchers, hospitals etc., use if steam is to be generated with cheap night electricity or if large amounts of steam are required for a short time, but only connections with low electrical power are available. For this purpose, the liquid steam generator is in each case without building capacitor 8, 9, 11; the steam manifold 21 or the individual Steam lines 7 are to be provided with shut-off or control valves, and the condensate return line 10 is connected to a water reservoir instead of the condensation space 8.

With the liquid steam generator according to the invention it is possible to take advantage of the cheaper electricity during the so-called off-peak times and heat up the steam generator. This stored heat can then be converted to any Point in time to be used. It is also possible to have low, long-lasting Converting performance into high performance over a short period of time, d. H., the heat storage in the steam generator becomes slow with weak electrical power charged and this stored energy can suddenly be used for the desired purpose hand over. This is especially beneficial in cases where only weak electrical Connection services are available, but large short-term services are required are.

Furthermore, the liquid steam generator according to the invention Advantage that with him the heat depends on the heat extraction by the final heat transfer medium is transmitted in a self-regulating manner. For this reason, the system is simple in structure; by the arrangement of the check valve 16 and the throttle device 15 in the expansion line 14 pressure fluctuations in the evaporator part are avoided.

In the embodiment of the liquid vapor generator in which the Condensation chamber 8 is relocated into the evaporator 6, it is advantageous that the Increase in volume of the heat-transferring liquid during the transition from the liquid in the vaporous or gaseous state is no longer to be taken into account. Particularly The embodiments of the liquid steam generator are also advantageous, in which the evaporator 6 or the parallel superposed evaporators 6 are arranged horizontally or slightly inclined. It is difficult and so far hardly was possible, such an intimate connection with vertically arranged evaporators to achieve and maintain the evaporator wall 5 with the heat accumulator 3, that the heat transfer from the heat accumulator 3 to the evaporator surface 5 entirely or occurs mainly through thermal conduction and not through the less favorable thermal radiation. Different thermal expansion of evaporator and heat storage and a work, d. H. Expansion of the evaporator even at low pressures, caused after a few Operating time a separation of the evaporator wall from the heat storage and thus a reduction the heat transfer, which then takes place to a much lesser extent through radiation. One Increase in the usable, lower temperature limit of the heat storage tank and thus a the consequences are poorer utilization of its storage capacity. With the mentioned Embodiments of the liquid steam generator eliminate these disadvantages avoided that the weight of the heat storage device is used to the for an optimal heat transfer, wholly or mainly through thermal conduction, is necessary to establish intimate contact between the heat accumulator and the evaporator, independently from any expansion or contraction of the evaporator. Because of her Weight, the heat accumulators are always on the below or between them arranged evaporators and enable a heat transfer by means of heat conduction. The efficiency of the heat storage and thus of the entire device is considerable improved.

Claims (7)

Claims: 1. Provided with a heat storage device, electrically heated liquid steam generator, in which the heat storage is its Heat by evaporating and condensing a liquid in a heat exchanger to the final heat transfer medium to be heated, d a -characterized in that the Evaporator (6) at its lowest point via an expansion line (14) with a at least the same volume as the expansion tank having the evaporator (17) is connected, at the junction of the expansion line one of a Throttle device (15) bypassable and the return flow of the condensate into the evaporator shut-off check valve (16) is provided while in the expansion line between the evaporator and the check valve as well as the throttle device - a vapor separator (19) is switched on. 2. Liquid vapor generator according to claim 1, characterized in that the expansion vessel in the outlet line (13) of the End heat carrier is provided on the condenser, so that the expansion line (14a) from the evaporator including check valve (16) and throttle device (15) to the outlet line of the final heat transfer medium can be connected (Fig. 2). 3. Liquid vapor generator according to claim 1 or 2, characterized in that the evaporator (6) and the condenser (8, 9, 11) are connected to one another by a pipe (7, 10). 4. Liquid steam generator according to claim 1 or 2, characterized in that the evaporator (6) is connected to the condenser (8, 9, 11) by a steam line (7) and a condensate return line (10 a, 10 b) , wherein in the The condensate return line of the steam separator (19) is switched on (FIG. 3). 5. Liquid steam generator according to claim 1 or 2, characterized in that when several evaporators (6) are used, they are connected in parallel via a common steam collecting line (21) and a common condensate return line (10) with the condenser (8, 9, 11) , wherein the steam collecting line can also be connected to the expansion line (14) (Figs. 6, 8). 6. Liquid steam generator according to claim 5, characterized in that the evaporators (6) open on the steam outlet side in parallel via individual steam lines (7) into the steam collecting line (21) and each via a further connecting line (24) with the condensate inlet end of the next evaporator (6 ) are connected and only the first evaporator (6) is directly connected to the condensate return line (10) (FIG. 8). 7. Liquid steam generator according to claim 1 or 2, characterized in that when using several evaporators each evaporator (6) has a steam line (7) to the condenser (8, 9, 11) and opens parallel on its condensate inlet side into the common condensate return line (10) (Fig. 9). Documents considered: German Auslegeschrift No. 1 146 602.