Steam generator and heating system with steam generator, as well as a method for operating such a steam generator

Abstract

The invention relates to a steam generator (2) with a housing (5) and elements arranged therein rotating about parallel axes of rotation (D), wherein the movement of the rotating elements is coupled and the elements, in conjunction with an inner wall of the housing (5), form movable chambers (6), an ignition device (8) for triggering an explosive oxidation process in the chambers (6) is provided in the housing (5) near the inner wall, and lines (L1-L4) leading to the area of ​​the inner wall of the housing (5) are provided in the housing (5), through which gaseous fuels and water (H2O) can be supplied to the chambers (6) from the inner wall of the housing (5) and water vapor (H2O(g)) can be discharged.The rotating elements are formed by two gears (3) with a plurality of teeth, which divide the chambers (6). The tips of the teeth are positioned directly adjacent to the inner wall of the housing (5) over a portion of the circumference and project into the chambers (6) of the adjacent gear (3) in an intermediate region (7). The openings of the lines (L1-L4) and the ignition device (8) are distributed along the inner wall of the housing (5) in relation to the teeth of the gears (3). The positions of the openings of the lines (L1-L4) and the ignition device (8) are arranged sequentially in the direction of rotation of the gears (3) in a mirror-symmetrical manner about a central plane (E) through the intersection points of the outer circles of the gears (3). Such a steam generator (2) can be part of a heating system (1).

Description

[0001] The present invention relates to a steam generator, in particular a steam generator that is part of a complex heating system.

[0002] Steam boilers are well known; these are closed, heated pressure vessels or pressure pipe systems that serve the purpose of generating steam or hot water at temperatures above 110°C for heating and operational purposes.

[0003] Furthermore, there are also boilers that can be operated with hydrogen. The problem here is that when hydrogen and oxygen are mixed and ignited, a highly energy-efficient and explosive combustion process occurs, making it difficult to control.

[0004] A rotary piston engine, in which a hydrogen-air mixture is burned, is known from EP 0 837 219 A1. This engine has two rotary pistons rotatably mounted in a housing, whose axes of rotation are parallel and which are designed such that the opposing line segments of their circumferential surfaces maintain a constant distance from each other in all rotational positions over one revolution of the two rotary pistons. The two rotary pistons are located between the inlet and outlet of the housing. Hydrogen and oxygen are used as fuel, which are supplied separately to the interior of the housing via the inlet. The two rotary pistons are coupled for counter-rotation at the same rotational speed, for example by means of gears or toothed belts. The rotary pistons are arranged with a 90° phase shift.Water sprayed into the combustion chamber reduces the combustion chamber temperature and increases the operating pressure. This rotary piston engine requires two complexly designed and manufactured, meshing rotary pistons to generate torque for propulsion using the steam pressure.

[0005] A gear-rotor motor is known from CN 1 08 035 796 A, comprising a housing and two gears arranged therein, rotating about parallel axes of rotation, whose movement is coupled and which mesh with each other. The gears form chambers with an inner wall of the housing. Conduits for fuel and water leading to the inner wall of the housing are provided, the arrangement being mirror-symmetrical with respect to the two gears. Furthermore, an ignition device for initiating an explosive oxidation process in the chambers is provided in the housing near an inner wall. Air is supplied from the front, and exhaust gas is discharged from the opposite side.

[0006] The object of the present invention is to provide a steam generator that is as simple in design as possible and operates safely and reliably without complex technical measures.

[0007] This problem is solved by a steam generator having the features of claim 1.

[0008] The steam generator comprises a housing and elements arranged therein that rotate about parallel axes of rotation. The movement of the rotating elements is coupled, and the elements, in conjunction with an inner wall of the housing, form movable chambers for explosive oxidation processes. An ignition device for initiating the explosive oxidation process is provided in the housing near the inner wall. Furthermore, lines leading to the area of ​​the housing's inner wall are provided within the housing, through which gaseous fuels (in particular H₂ and O₂) and water (H₂O) can be supplied to the chambers from the inner wall of the housing, and water vapor (H₂O(g)) can be discharged. According to the invention, the rotating elements are formed by two gears with a plurality of teeth, which divide the chambers.The tips of the teeth are positioned directly adjacent to the inner wall of the housing over a portion of the circumference and project into the chambers of the adjacent gear in an intermediate region. The openings for the conductors and the ignition device are distributed across the inner wall of the housing in relation to the teeth of the gears, with the positions of the openings, conductors, and ignition device being arranged sequentially, mirror-symmetrically to a central plane through the intersection points of the outer circles of the gears in the direction of rotation of the gears.

[0009] According to the invention, the arrangement of openings of the lines and the ignition device in the inner wall of the housing in the direction of rotation of the gears is as follows: opening of the line for supplying the first gaseous fuel, opening of the line for supplying the second gaseous fuel, opening of the ignition device, opening of the line for supplying water, and opening of the line for removing water vapor.

[0010] In pure steam generation, as envisaged here, no torque generation is required, so simple rotary systems can be used. The gap between two teeth forms the chamber for the oxidation process. The chambers have a relatively small, constant size (at least over the injection and combustion phases), which also facilitates the control of the explosive oxidation process. In contrast to conventional steam boiler processes, where steam generation occurs through heat transfer across large wall surfaces, the steam generator according to the invention allows for small designs and, due to the small surface area, also low energy losses. Manufacturing is significantly more cost-effective due to the reduced material and production costs.

[0011] During the oxidation process, a very high temperature (up to over 3000°C) is generated in the chamber. The injection of water, which immediately evaporates and thus cools, lowers the steam temperature, preferably to 400–600°C, and increases the steam volume. The additional steam generated as a result of the injected cooling water increases the steam pressure in the steam-condensate cycle in which the steam generator is located. This steam can then be used to drive a power engine (steam engine or turbine) for optimized energy utilization.

[0012] By selecting the number of teeth, the number and size of the chambers can be optimized, which in turn optimizes the mixing of the fuels and the oxidation process in individual phases.

[0013] Particularly preferably, the opening of the line for supplying the first fuel is arranged adjacent to the intermediate area in the direction of rotation of the gears, and the opening of the line for supplying the second fuel is arranged offset by at least two teeth in the direction of rotation of the gears to the opening of the line for supplying the first fuel.

[0014] Particularly preferably, the opening of the ignition device is offset by at least two teeth in the direction of rotation of the gears after the opening of the line for supplying the second fuel. This distance ensures sufficient mixing of the fuels for optimal combustion.

[0015] The number of teeth on the gears is preferably at least eight. In particular, when designing the steam generator for high rotational speeds and with small chambers, a larger number of teeth allows for a more economical size of the steam generator.

[0016] Such a steam generator is preferably integrated into a heating system. To increase efficiency, the steam from the steam-condensate cycle is directed into a heat exchanger system (condensate heat exchanger and, if necessary, further heat exchangers), thus forming an optimal combined heat and power (CHP) system.

[0017] A very high efficiency is achieved by cooling the exhaust steam in a condensate heat exchanger to below the condensation temperature. The resulting condensate is then used for injection into the chambers, thus creating a closed system loop.

[0018] In particular, the excess condensate from combustion is preferably collected and used for electrolysis and thus for the reproduction of the fuels.

[0019] The invention is explained in more detail below with reference to an embodiment illustrated in the drawing. The drawing shows... Fig. 1 a steam generator according to the invention, Fig. 2 a cross-section through a condensate heat exchanger, Fig. 3 a cross-section of the condensate heat exchanger of Fig. 2, and Fig. 4 A functional diagram of a heating system with steam generator and condensate heat exchanger.

[0020] A key component of a heating system 1 powered by gaseous fuels is a steam generator 2. Hydrogen (H2) and oxygen (O2) are supplied to this generator in gaseous form. Preferably, the hydrogen and oxygen used for this purpose are produced by electrolysis, for example, using solar or wind power.

[0021] The steam generator 2 has two gears 3 with parallel axes of rotation 4, each with eight teeth, which mesh essentially without contact and are rotatably arranged in a housing 5. The housing 5 is essentially mirror-symmetrical about a median plane E (defined by the plane passing through the intersections of the tip circles of the gears 3). The distance between the rounded tips of the teeth and the inner wall of the housing 5 is minimized and optimized with regard to friction and pressure losses. The teeth, in conjunction with the housing 5, form small, rotating chambers 6. In an intermediate region 7, where the tips of the teeth do not directly face any inner wall, these chambers open towards the adjacent chambers 6 of the other gear 3. The intermediate region 7 is located within the housing 5 in the region of the median plane E.

[0022] Lines L1-L4 in housing 5 allow, via corresponding openings in the inner wall of housing 5, the controllable supply of oxygen O2, hydrogen H2, water H2O, and the removal of water vapor H2O(g). The term "openings of the lines" hereafter also includes injection nozzles or other devices that enable the injection or introduction of gaseous fuels or water into the chambers.

[0023] The oxygen supply via line L1 is located – viewed in the direction of rotation of the gears 3 – after the intermediate section 7. Two teeth further along in the direction of rotation of the gears 3, the hydrogen supply is located via line L2. Two teeth further along, an ignition device 8 in the form of a glow plug is provided. The distance between the second line L2 and the ignition device 8 should generally be at least two teeth to ensure sufficient mixing of the fuels. In the area of ​​the last chamber 6 before the intermediate section 7, viewed in the direction of rotation of the gears 3, a line L3 is provided for the supply of cooling water. Opposite the oxygen supply, and positioned before the intermediate section 7 in the direction of rotation of the gears 3, a line L4 is provided for the removal of water vapor.

[0024] The gears 3 are driven via a transmission (not shown in detail), in this case a gear transmission, with the speeds being regulated by a control gear. This serves in particular to relieve the teeth of the gears 3, which are thus coupled to each other without contact.

[0025] The function of the steam generator 2 is briefly described below. The gears 3 rotate in the housing 5 in the Fig. 1. Opposing directions indicated by arrows with corresponding rotational speeds. The following refers only to the upper gear 3. The process for the lower gear 3 occurs slightly later.

[0026] Oxygen is supplied to chamber 6, which rotates in front of the opening of line 1, via line L1. The two chambers 6 of the interlocking gears, which open after the intermediate section 7, create a vacuum, drawing in the oxygen. The oxygen-filled chamber 6 continues to rotate continuously counterclockwise. It is briefly "closed," during which time the oxygen distributes itself within the chamber 6. The chamber 6 then moves in front of the opening of line L2, through which hydrogen is supplied in a controlled manner and in a stoichiometric ratio to the oxygen in chamber 6. This results in a pressure of approximately 1 bar inside chamber 6. As chamber 6 continues to rotate, the hydrogen and oxygen mix before it opens towards the ignition device 7, which initiates a controlled ignition. Subsequently, the hydrogen is combusted to water at high speed.As the rotation continues, the combustion process continues. At the end of the combustion, chamber 6 contains steam at a pressure of approximately 11 bar. At this point, chamber 6 has rotated in front of the opening of line L3, through which water is injected. This water evaporates, causing cooling and resulting in a steam temperature of approximately 400°C to 600°C. Shortly before chamber 6 reaches the end of the inner wall of housing 5, it passes in front of the opening of line 4. The pressurized steam that has formed in chamber 6 is released through this opening by the other gear closing chamber 6, making it available for other uses. Chamber 6 then reaches the intermediate section 7, where it opens towards chambers 6 of the other gear 3 and, through further rotation, returns to its initial position.

[0027] The volume of the rotating chambers 6 can be changed by arranging partitions, but remains constant during operation. Variations are possible, in particular, with regard to the number of rotating chambers around the circumference, the diameter of the gears, and the length (in the direction of the axis of rotation), whereby the volume of the chambers 6 should be kept as small as possible. Performance adjustment is possible, in particular, by varying the rotational speed.

[0028] By using relatively small reaction chambers with constant volume in the form of chambers 6, the steam generator 2 according to the invention enables controlled combustion. Heat losses to the outside can also be easily minimized. Due to the injection of water, the steam temperature can be reduced to 400°C–600°C, which allows the system temperature to be kept relatively low. This enables the use of cost-effective materials.

[0029] The supply of the two fuels, oxygen and hydrogen, can also be carried out in reverse order. It is important that the two fuels are supplied in a stoichiometric ratio.

[0030] The heating system 1, of which the previously described steam generator 2 is an essential component, will be explained in more detail below.

[0031] Heating system 1 has two circuits, namely a heating circuit H and a steam condensate circuit D.

[0032] The said steam condensate cycle D includes the previously described steam generator 2, a heat exchanger 11 and / or a turbine 12 and / or a steam generator 13, a condensation heat exchanger 14, a condensate storage tank 15, a collection tank 16, an electrolysis device 17, a storage tank 18 for oxygen and a storage tank 19 for hydrogen.

[0033] The heating circuit H in this case has a heater 20 as well as the aforementioned heat exchanger 11 and / or the aforementioned condensation heat exchanger 14, i.e. heat exchanger 11 and / or condensation heat exchanger 14 are the areas in which heat is transferred from the steam condensate circuit D to the heating circuit H.

[0034] The steam generated in the steam generator 2 travels via pipes to the heat exchanger 11, where it transfers heat to the heating circuit H, in which the heater 20 is located. The steam then travels via pipes to the condensation heat exchanger 14, where it is liquefied, releasing further heat. The condensate (water) collects and is fed in a controlled manner to the condensate storage tank 15.

[0035] From the condensate storage tank 15, part of the water is fed directly to the steam generator 2 as cooling water by means of a condensate pump 21.

[0036] Excess water from the condensate storage tank 15 flows via an overflow into the collection tank 16, from where it is pumped 22 to the electrolysis unit 17 and split into oxygen and hydrogen using electricity. The oxygen is stored in storage tank 18, the hydrogen in storage tank 19, and supplied to the steam generator 2 via pipes as needed.

[0037] In heating circuit H, a heat transfer medium, in this case water, is supplied to the heater 20, from which the heat is used, for example, to heat a living space. Heating circuit H is circulated by a heating circuit pump 23 located downstream of the heat output and enters the condensing heat exchanger 14 at a temperature of approximately 40-50°C. In the first heat transfer step, heat is absorbed from the steam condensate circuit D, and the temperature rises to approximately 50-70°C. A second heat transfer step then takes place in heat exchanger 11, during which heat is also transferred from the steam condensate circuit D to heating circuit H. The heat transfer medium, heated by these two successive heat transfer steps, returns to the heater 20. A heat storage tank can also be provided in heating circuit H to temporarily store heat.

[0038] It goes without saying that heat losses to the outside of heating system 1 are minimized in circuits H and D.

[0039] Referring to Fig. 2 and Fig. Section 3 below describes in more detail the condensation heat exchanger 14, which is part of the two circuits H and D. The condensation heat exchanger 14 has a substantially cylindrical central section 31, an upper dished end 32 with a dome 33, a lower dished end 34 which has a larger diameter than the central section and is flattened at the bottom, and a ring line 35 which runs around the lower section of the central section 31 and connects to the lower dished end 34.

[0040] Inside the condensing heat exchanger 14, J-shaped bent tubes 36 run in two concentric circles, spaced apart from each other. The long end of each tube terminates in the upper dished end 32, the bent section runs in the lower dished end 34, and the lower end terminates in the ring main 35. A base with openings for the tube ends separates the upper dished end 32 from the middle section 31.

[0041] The condensing heat exchanger 14 is part of both the steam-condensate circuit D and the heating circuit H. In the steam-condensate circuit D, water vapor H₂O(g) enters the area of ​​the upper dished head 32 via a pipe and from there, via the J-shaped bent tubes 36, into a heat exchange zone where the water vapor condenses, so that hot water predominates in the lower section of the tubes 36. This water flows from the J-shaped bent tubes 36 into the ring main 35, located above the lower dished head 34. A temperature-controlled outlet valve regulates the outflow via a pipe into the condensate storage tank 15. In this case, the outlet valve closes at a temperature above 60°C. If the steam pressure rises as a result of the closed outlet valve, the system is switched off.

[0042] A valve is provided in the upper area of ​​the dome 33 to release excess gas, which is lighter than the steam, that collects in the dome 33 and thus remove it from the steam-condensate circuit D. This gas could be, for example, oxygen, which remains in the steam during incomplete combustion and accumulates in this area of ​​the condensation heat exchanger 14.

[0043] In the area of ​​the heating circuit H, “cold” water (approx. 40°C to 50°C) coming from the heating system 20 enters the area of ​​the lower dished end 34 and flows at low speed along the J-shaped bent pipes 36 into the upper area until below the upper dished end 32, where it is discharged via a pipe at a temperature of approx. 50°C to 70°C. Reference symbol list 1 Heating system 2 steam generators 3 gear 4 axis of rotation 5 cases 6th Chamber 7 Intermediate area 8 Ignition device 11 heat exchangers 12 Turbine 13 Steam generator 14 Condensation heat exchangers 15 condensate storage tanks 16 collection containers 17 Electrolysis device 18 oxygen storage 19 hydrogen storage facilities 20 Heating 21 Condensate pump 22 Pump 23 Heating circuit pump 31 middle range 32 upper dished head 33 Cathedral 34 lower dished head 35 Ring main 36 pipe D Steam condensate cycle E Middle plane (passing through the intersection points of the gear pitch circles) H Heating circuit H2 hydrogen H2O water H2O(g) water vapor L1-L4 line O2 Oxygen

Claims

[1] Steam generator (2) with a housing (5) and elements arranged therein which rotate about parallel axes of rotation (D), wherein the movement of the rotating elements is coupled and the elements form movable chambers (6) in cooperation with an inner wall of the housing (5), an ignition device (8) for triggering an explosive oxidation process in the chambers (6) is provided in the housing (5) near the inner wall, in the housing (5) there are provided lines (L1-L4) leading to the area of ​​the inner wall of the housing (5), via which lines gaseous fuels and water (H2O) can be supplied to the chambers (6) from the inner wall of the housing (5) and water vapor (H2O(g)) can be removed, wherein the rotating elements are formed by two gear wheels (3) with a plurality of teeth which divide the chambers (6), the tips of the teeth are positioned over part of the circumference directly adjacent to the inner wall of the housing (5) and protrude into the chambers (6) of the adjacent gear (3) in an intermediate region (7), the openings of the lines (L1-L4) and the ignition device (8) are arranged distributed over the inner wall of the housing (5) in relation to the teeth of the gears (3), wherein the position of the openings of the lines (L1-L4) and the ignition device (8) in the direction of rotation of the gears (3) are each arranged mirror-symmetrically to a center plane (E) through the intersection points of the outer circles of the gears (3) successively, characterized by that the arrangement of openings of the lines (L1-L4) and the ignition device (8) in the inner wall of the housing (5) in the direction of rotation of the gears (3) is as follows: Opening a line (L1) for supplying a first gaseous fuel, Opening a line (L2) for supplying a second gaseous fuel, Opening of the ignition device (8), Opening of a pipe (L3) for supplying water, and opening a line (L4) for discharging water vapor. [2] Steam generator (2) according to claim 1, characterized by that the opening of the ignition device (8) is arranged offset by at least two teeth in the direction of rotation of the gear wheels after the opening of the line for supplying the second gaseous fuel (L2). [3] Heating system (1) comprising a steam generator (2) according to one of the preceding claims. [4] Heating system (1) according to claim 3, characterized by that the heating system (1) has a heating circuit (H) and a steam-condensate circuit (D), wherein part of the steam-condensate circuit (D) is said steam generator (2) and a condensation heat exchanger (14) to which steam from the steam generator (2) can be supplied. [5] Heating system (1) according to claim 4, characterized by that the heating system (1) has an electrolysis device (17) in which at least a part of the water from the steam-condensate circuit (D) can be electrolyzed to oxygen (O2) and hydrogen (H2), and at least a part of the oxygen (O2) thus produced and at least a part of the hydrogen (H2) thus produced can be fed to the steam generator (2). [6] Heating system (1) according to one of claims 4 to 5, characterized by that the steam-condensate circuit (D) is a closed circuit. [7] Heating system (1) according to one of claims 4 to 6, characterized by that the condensation heat exchanger (14) has a dome (33) with a valve in which gas which is lighter than steam collects. [8] Heating system (1) according to one of claims 5 to 7, characterized bythat the steam-condensate circuit (D) has, in addition to the condensation heat exchanger (14), a further heat exchanger (11) and / or a turbine (12) and / or a steam generator (13). [9] Method for operating a steam generator (2) according to one of claims 1 to 2, characterized by that the first gaseous fuel is sucked in and the second gaseous fuel is injected in a stoichiometric ratio to the first gaseous fuel.

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