WO1997032113A1

WO1997032113A1 - Steam engine plant comprising a condenser system

Info

Publication number: WO1997032113A1
Application number: PCT/SE1996/000255
Authority: WO
Inventors: Ove Platell
Original assignee: Ranotor Utvecklings Ab
Priority date: 1994-08-29
Filing date: 1996-02-28
Publication date: 1997-09-04

Abstract

The invention relates to a steam engine plant with a condenser buffer (1) partly filled with liquid, and a radiator (12) provided with a cooling device. The condenser buffer (1) shall have the ability to condense all arriving steam from the steam outlet pipe (5) of the steam engine also at very high, instantaneous power outputs from the steam engine, which may be the case for instance when the plant comprises a stem buffer (18), which is capable of multiplying the maximum steam flow to the condenser buffer (1). The condensing should be performed at a low sound-level, that is without imploding steam bubbles. According to the invention all steam is arranged in the steam buffer to be fed to channels (7) having walls which are provided with a large number of fine openings (8), which all are located below the liquid level in the condenser buffer (1) at different depths and with areas adapted such that the steam exhaust will occur in the shape of concentrated jets (24) of steam in the liquid surrounding the channels. According to a preferred embodiment the bottom parts of the channels (8) are further provided with outlet openings (26) with large area and with valves in the shape of buoyant bodies (27), which restrict or close the outlet openings (26) when the liquid level in the channels (8) approaches the outlet openings.

Description

STEAM ENGINE PLANT COMPRISING A CONDENSER SYSTEM.

The present invention relates to a steam engine plant of the kind set forth in the introduction of the accompanying claim 1.

Steam engine plants of this kind are previously known which are big and heavy and which have a low power as compared to the size. Especially the accompanying condenser systems are space consuming and have in spite of a large number of auxiliary devices an insufficient condensing capacity for enabling operation in a hermetically closed system. This is partly the reason why the development of steam engine plants since a long time ago has ceased, particularly plants for driving vehicles and boats.

By utilizing modern steam technique with advanced steam data and by utilizing a high-power steam buffer it is possible, however, to achieve extremely good performance, and recently highly efficient steam engine plants have been known, as shown in WD 95/35430, WD 95/35432 and WD 95/35433. In order to enable a complete utilizing of such a plant it is necessary to have access to a correspondingly efficient and a practically noiseless condenser device.

A condenser device of that type has not been accessible up to now. As an instance of known condenser devices the device shown in the US 3,237,413 can be mentioned. This is a steam power plant having a partly water filled condenser buffer with a special space into which vertical steam pipes stick down, which pipes are provided with openings, which are positioned partly above and partly below the water surface of the condenser buffer. When a strong steam flow is directed down into the pipes and an attached, condensing radiator does not necessarily have the sufficient instantaneous cooling capacity for condensing this flow, the pressure in the condenser system will rise rapidly to injurious values as all the steam cannot condense in the water of the condenser buffer.

Another example of a known condenser device for a steam engine plant is described in DE 1 936 576. Here the steam is fed down to the bottom of a partly water filled condenser which through a pipe socket communicates with the atmosphere. There is no possibility to avoid a pressure rise in the steam circuit when the steam flow increases, and no condensing device for cooling the water in the condenser is utilized, only a water radiator with a circulation pump. In order to avoid the need of filling up with working medium it is a must for an efficient steam engine plant that the working medium, preferably water/steam, is hermetically enclosed and, thus, forms a completely closed system. This means, that the working medium has to be enclosed in the plant at the manufacture and after that does not need to be refilled during the life of the plant, except possibly for inspection purposes at service occasions.

The completely closed steam system also requires, however, that the condensing sub-system has the capacity to condense the highest instantaneous flows of outlet steam from the steam engine that might occur. If the condensing system cannot condense all the steam flow the pressure will rise quickly and working medium will get lost because steam must have the possibility to escape through a safety valve.

A steam plant of the kind described in the above mentioned WD-publications which works with admission steam at high pressure and high temperature, especially supercritical steam, and which has a piston engine operated as an expander can give rise to extremely high efficiency in relation to the weight and will by utilizing the high power deliver very high flows of outlet steam to the condenser system. These high efficiency peaks, which always have a short duration, have a magnitude, however, that makes it impossible for the air-cooled condenser to transmit this heat transfer instantaneously to surrounding air without special measures.

The object of the present invention, hence, is to accomplish a solution of this problem with a condenser system for a completely closed system that has an extremely high power and that works automatically and extremely silent.

This is achieved according to the invention by the fact that in the steam engine plant mentioned by way of introduction all outlet steam from the steam engine is arranged in the pressure container to be supplied to channels with walls, which are provided with a great number of small openings, which all are located below the liquid surface of the pressure container at different depth levels and with areas adapted such, that the steam exhaust through the openings which are uncovered from liquid in dependence of the steam pressure prevailing in the channels always occurs in the shape of jets of steam out into the the surrounding liquid.

In a specially preferred embodiment of the invention having the capability of overcoming the largest steam flows the bottom parts of the channels are provided with outlet openings with large area and valves controlled in dependence of the liquid level in the channels for restricting the outlet openings when the liquid level in the channels are getting near to the outlet openings.

The essentially new of the invention is, that the steam is made to condense in the water more or less noiseless in the water due to the fact that the steam is exhausted into the water through the small openings and with a determined least velocity. It has turned out namely that steam that with an uncontrollable, low velocity streams through an opening below the water level has a bad condensation and forms comparatively large steam bubbles, that with strong bangs collapse or implode in the water. At increasing velocity the steam bubbles become smaller and smaller and more or less cease at a certain lowest velocity, in which case an instantanious more or less noiseless condensation occurs in that the steam flows out in the shape of jets of steam. This is achieved by the plant according to the invention already at low steam flows in that only the upper openings are active. If the steam flow increases more openings become active when the liquid level in the channels drop under the influence of the increasing steam pressure. It is easily seen that at each pressure the number of active openings becomes the required for the steam to flow out through these in the shape of jets of steam.

It is also desirable that the condenser system is able to work automatically with rapid response when the steam flows to be condensed vary quickly between maximum and minimum values. This is obtained thanks to the large area outlet openings in the bottom parts of the channels provided with the simple valves active in the openings. A great increase of the steam flow has to be swallowed by the channels without much pressure increase. The velocity of the liquid pressed downwards in the channels by the steam would be insufficient if all the liquid had to be pressed out through the small openings, which should result in a harmful increase of pressure. The presence of said large area outlet openings permits a rapid discharge of the liquid through these openings without appreciable increase of the pressure. Normally, there is time for the steam pressure to decrease until the level of the liquid in the channels has sunk to the bottom parts of the channels. If the level should sink further, exhaust of steam through these openings is prevented. Otherwise a deteriorated condensing should have been obtained and also an ear-splitting noise. Hence, this is prevented by said valves, which throttle the openings. The valves may consist of simple buoyant bodies, which when the liquid-level approaches the bottom parts of the channels cover the outlet openings.

The problems involved with a rapid and a least possible noisy condensing of especially an instantaneously, rapidly increasing steam flow has been solved by the plant according to the invention. An efficient cooling of the liquid in the condenser buffer is of the greatest importance. A conventional radiator or condenser provided with a pump for returning the condensed steam to the condenser buffer is not efficient enough. Especially an air-cooled radiator has a very varying condensing capacity, and in the plant according to the invention is it of great value if this capacity can be utilized to an optimum. This is possible in an embodiment according to a preferred embodiment of the invention, in which the effective volume of the radiator is located all above the liquid-level of the condenser buffer, which is provided with a steam pipe, that connects the upper part of the condenser buffer with the upper part of the radiator, and a return pipe for condensed steam, which pipe connects the bottom part of the radiator with a part of the condenser buffer located below the liquid-surface. At all working conditions the condensation of all outlet steam from the steam engine is effected in the condenser buffer. If the cooled radiator does not have a cooling capacity corresponding to the power delivered by the steam engine the temperature of the condenser buffer will increase. In a vehicle application the radiator is air-cooled and its cooling capacity is dependent on the speed of the vehicle and the temperature of the steam. None of these is particularly favourable in the beginning of a high-power output from the steam engine, but at the end of this power output when the temperature of the condenser buffer and normally also the speed of the vehicle has increased due to the high-power output, the air-cooled radiator always gets a strongly increased cooling capacity. By the arrangement set forth in claim 6 a heat-pipe function is achieved between the radiator and the condenser buffer such that when the cooling capacity of the radiator increases this cooling capacity is automatically connected to the condenser buffer. Hence, an optimum cooling of the condenser buffer is achieved without use of pumps, regulating means or some other active system by means of the air-cooled radiator which responds to the need of cooling capacity of the condenser buffer with its own increased cooling capacity obtained by the very increased temperature of the buffer. This means that the pressure and temperature of the condenser system can be kept below the desired about 3 bar and 13 °C, respectively, also during and directly after a high-power outlet. The advantage of the heat-pipe function in a very application of this kind can be explained by the fact, that the same temperature and pressure values prevail all over the condenser system. These values are determined by the liquid temperature in the condenser buffer. As soon as the radiator by some reason gets increased cooling capacity the steam present in the radiator becomes condensed. Thereby the pressure in all the condenser system has a tendency to decrease, which is counteracted by a spontaneous steam evaporation from the condenser buffer liquid. This results in a very intense heat transmission between the condenser buffer and the radiator. Condensed steam flows by itself back to the condenser buffer in perfect correspondence to the instantaneous cooling capacity of the radiator.

The invention is described in the following in more detail with reference to the attached drawings, which schematically illustrate various embodiments of condenser buffers for steam engine plants according to the invention and on which Figure 1 is a longitudinal section through a first embodiment of a condenser buffer with an attached radiator shown as a side view, Figure 2 is a cross section through the condenser buffer shown in Fig.l, Figure 3 is a section of a detail of the condenser buffer shown in Figs.l and 2, Figure 4 is a section of a detail showing an outlet opening in Fig.3, Figure 5 is a longitudinal section through a second embodiment of the condenser buffer, Figure 6 is a section through a detail of a condenser buffer according to a further embodiment, and Figure 7 is a section of a detail of outlet openings of the embodiment according to Fig.6.

The condenser buffer 1 shown in Fig.l has a housing formed by a cylindrical wall 2 and two circular, slightly domed end walls 3 and 4. The housing is designed to withstand at least the pressure of about 3 bar which might occur at the supply of outlet steam from the steam engine via a steam pipe 5, which steam is is supplied via a distribution chamber 6 mounted close to the top of the housing and provided with a great number of distribution pipes 7 directed downwards with closed bottom ends and small outlet openings for the steam placed in close proximity to each other. The condenser buffer 1 is filled with water 9 approximately up to the upper ends of the pipes 7 such that all the openings 8 always are located below the water surface 10. An opening in the end wall 3 above the water surface is connected by a steam pipe 11 to a conventional air-cooled radiator 12 from which a return pipe 13 conveys condensed steam to an opening in the end wall 3 close to its bottom part. Further, in the bottom part of the end wall 4 there is an opening to which a pipe 14 is connected for supply of condensate to a feed pump 15 which feeds condensate to a steam generator 16, from which steam is fed to a steam engine 17 via a steam buffer 18.

Figs.l and 2 show the condition in the condenser buffer 1 when no steam is supplied from the steam engine 17, viz. the water level inside the perforated pipes 7 is essentially equal to the water level 10 outside the pipes. When steam is supplied via the pipe 5 and the distribution chamber 6 the pressure in the chamber increases and the water level inside the pipes 7 sinks such that more and more of the openings 8 are uncovered when the pressure rises as shown in Fig.3. It has proved, that it is very important that the exhaust of steam through the openings 8 is effected with a velocity of flow that does not go under a lowest limit value. If not, the steam flowing out through the openings will form a row of steam bubbles which condense in the water and rapidly collapse - implode - generating loud bangs, which in this connection is quite unacceptable. When the outflow velocity increases above said limit value a dramatic change occurs in that the steam bubbles cease and instead a fine steam jet is formed going out from each uncovered opening 8, which steam jet extremely rapid starts condensing against the surrounding wall of water, at which the remainder of the steam jet rapidly narrows conically to a point, where the condensing is complete, and at the same time the steam jet tears with itself particles of the surrounding water during transformation of the kinetic energy of the steam jet 24 to a water flow 25 having a corresponding kinetic energy. Due to the fact that no steam bubbles implode any more the condensation will be quite noiseless.

This way of working is obtainable without movable regulating means or similar means and with the highest condensing capacity by arranging the openings 8 as shown in Figs.1-3. At a low pressure in the pipes 7 only the upper openings 8 are uncovered and the velocity of the outflowing steam is forced up to above the said limit value. At increasing pressure further openings 8 are uncovered. Said velocity will be mainly unchanged but the condensing capacity will of course increase by the increasing number of uncovered openings 8.

At very rapidly changing flows of steam there is not time enough for the steam to flow out through the openings 8 for preventing an undesired increase of the pressure in the pipes. Therefore the bottom parts of the pipes are provided with outlet openings 26 with a large area and cooperating with these valves in the shape of buoyant bodies 27, which when the water levels in the pipes approach said openings choke them or close them. By that water is permitted to rapidly flow through the openings 26 without any appreciable pressure rise, but at the same time steam is prevented from blowing out through the openings, which should result in decreased condensing capacity and a high noise.

As mentioned above, the outflowing steam has the characteristic - before it has condensed - to be able to tear with itself a layer of adjacent water, which after that together with the condensate form a water jet, which is preferable for the rising water temperature during the condensation to be fairly distributed in the buffer 1. An amplification of this function is obtained if the openings 8 are provided with a corbelling 19, as shown in Fig.4.

The distribution chamber 6 with the pipes 7 can as an alternative be replaced by the chamber 20 shown in Fig.5. This has the shape of a wide, flat, oblique chamber extending from the water surface 10 down towards the bottom of the cylindrical wall 2. All sides of the chamber 20 are provided with steam outlet openings 8. Hence, the openings are located at different depth, as illustrated by the eiribodiment in Figs.1-4 The working at different pressures will be essentially unchanged, but with the chamber 20 a faster response is obtained at sudden changes of pressure than is the case with the pipes 7.

Another alternative is shown in Fig.6. The bottom wall of the distribution chamber 6 in Figs.1-2 here has been provided with hollow, vertical distribution plates 21 instead of the pipes 7. All sides of the plates 21 are provided with steam outlet openings 8, and the working is essentially the same as that of the previously shown embodiments. An improved stirring of the water 9 is obtainable, however, under the influence of the steam flowing out, if corbellings 22 are directed obliquely such that the steam flowing out from one side of the plate is directed obliquely downwards and at the other side obliquely upwards, as shown in Fig.7. Then a circulation 23 is formed between each pair of plates 21 such that the water temperature is equalized vertically, especially at high condensing capacities.

The invention is of course not limited to the shown and described examples of embodiments, but can be modified in various ways within the scope of the inventive idea defined by the claims. Hence, the steam outlet openings 8 may be circular or oval holes or elongated holes or a combination of such openings. The diameter or width of the holes can suitably be about 1 mm, but has - like the vertical distribution of the openings - to be tested from case to case in order to obtain optimum condensing capacity and noise level. At marine applications the radiator is preferably water- cooled instead of air-cooled.

Claims

C A I M S

1. Steam engine plant with a closed steam system, preferably for driving vehicles, comprising a steam generator (16) fed with liquid, preferably water, for generating steam of high pressure and high temperature, preferably at least critical temperature and critical pressure, a steam buffer (18), a reciprocating steam engine (17), and a condensing system consisting of a condenser buffer (1) and radiator (12) provided with a cooling device, at which a steam pipe (5) from the steam outlet of the engine is arranged to end in a pressure container (2-4) partly filled with liquid and serving as a condenser buffer (1) connected to the radiator

(12) , characterized in that all steam from the steam pipe (5) is arranged in the pressure container (2-4) to feed channels (7,20,21) having walls that are provided with a large number of fine openings (8) , which all are located below the liquid surface (10) in the pressure container at different depth levels and with areas adapted such, that the steam exhaust through the openings which are uncovered from liquid in dependence of the steam pressure prevailing in the channels always occurs in the shape of concentrated jets (24) of steam out into the surrounding liquid.

2. Steam engine plant according to claim 1, characterized in that the bottom parts of the channels (7,20,21) are provided with outlet openings (26) with large area and valves (27) controlled in dependence of the liquid level in the channels for restricting the outlet openings when the liquid level in the channels are approaching the outlet openings (26).

3. Steam engine plant according to claim 1 or 2, characterized in that the steam outlet pipe (5) in the pressure container (2-4) ends in the shape of a distribution chamber (6,7;20,-6,21) , which extends deep down into the liquid (9) and which has walls (7,20,21) in which the fine openings (8) are located.

4. Steam engine plant according to any of claims 1-3, characterized in that the fine openings (8) in the shape of round openings or elongated openings have edges (19;22) that are corbelled out.

5. Steam engine plant according to any of claims 1-4, characterized in that a number of the openings (8) are directed such that the steam jets from the openings (8) form a circulating path (23) that conveys a stirring of the liquid (9) in the buffer (1).

6. Steam engine plant according to any of claims 1-5, characterized in that the effective volume of the radiator (12) is locater" all above the liquid level (10) of the condenser buffer (1) , which is provided with a steam pipe (11) , that connects the upper part of the condenser buffer

(1) with the upper part of the radiator (12) and a return pipe (13) for condensate, which pipe connects the bottom part of the radiator with a part of the condenser buffer (1) located below the liquid surface.