EP4273373A1 - Plant with heat exchanger and plant operating method - Google Patents

Abstract

The invention relates to a system with a line (18) for an oxidant-containing gaseous heat transfer fluid, in which a heat exchanger (20) is arranged for exchanging heat between the oxidant-containing gaseous heat transfer fluid and a fluid containing flammable components, which has a heat exchanger inlet (50 ), through which the oxidant-containing gaseous heat transfer fluid can be fed from the line (18) into the heat exchanger (20), and which has a heat exchanger outlet (52) through which the oxidant-containing gaseous heat transfer fluid returns after flowing through the heat exchanger (20). can get into the line (18). According to the invention, the system contains a device (58) for triggering combustion of heat transfer fluid mixed with the fluid containing combustible components in the line (18) for the oxidant-containing gaseous heat transfer fluid.

Description

The invention relates to a system with a line for an oxidant-containing gaseous heat transfer fluid, in which a heat exchanger for exchanging heat between the oxidant-containing gaseous heat transfer fluid and a fluid containing flammable components is arranged, which has a heat exchanger inlet through which the heat transfer fluid from the Line can be fed into the heat exchanger, and which has a heat exchanger outlet through which the heat transfer fluid can get back into the line after flowing through the heat exchanger.

The invention also relates to a method for operating a system with a line for an oxidant-containing gaseous heat transfer fluid, in which a heat exchanger for exchanging heat between the oxidant-containing gaseous heat transfer fluid and a fluid containing combustible components is arranged, so that the heat transfer fluid the heat exchanger from a heat exchanger -Inlet for the heat transfer fluid to a heat exchanger outlet for the heat transfer fluid to flow through.

From the DE 21 2016 000 187 U1 a system and a method are known in which a gas is compressed, with the heat generated during compression being released via a heat exchanger to an ORC system (ORC = Organic Rankine Cyle) after the gas has been compressed.

The specific heat capacity of a gas is generally lower than the specific heat capacity of a liquid. In order to transfer the same amount of heat per unit of time in a heat exchanger from a primary side, through which a heat transfer fluid flows, to a secondary side of the heat exchanger, a gaseous heat transfer fluid must be moved through the heat exchanger with a larger mass flow than a liquid heat transfer fluid.

When transferring heat in a heat exchanger with gaseous heat transfer fluid, there is the advantage that this can generally be exposed to higher temperatures than liquid heat transfer fluid without phase transitions and/or chemical conversions occurring.

Air in particular is suitable as a heat transfer fluid for transferring heat from a primary side to a secondary side in a heat exchanger that can withstand temperatures T ≥ 1000 ° C and is freely available.

If a heat transfer fluid is used to transfer heat from the primary side to the secondary side in a heat exchanger to another heat transfer fluid, there is a risk that the two heat transfer fluids will mix if there are leaks in the heat exchanger. In particular, if one heat transfer fluid, such as air, has an oxidizing agent as a component due to the oxygen it contains and the other heat transfer fluid, such as an ORC working fluid, has flammable components, there is a risk that uncontrolled burns or even explosions can occur damage a system.

In order to avoid that the heat transfer fluid on a primary side of a heat exchanger can mix with the heat transfer fluid on a secondary side of the heat exchanger, it is known to design the heat transfer fluid channels in a heat exchanger to be double-walled. However, the technical effort involved in producing double-walled heat exchangers is high because special equipment and special materials are required for production.

In addition, it is known to design systems with lines in which flammable gas mixtures are carried at high temperatures to be explosion pressure-proof or explosion-pressure shock-proof, so that they are also resistant to explosions not take any damage. However, the measures to be taken for this are complex and result in many assemblies and elements of the system being oversized for normal operation.

The object of the invention is to provide a system in which heat can be reliably transferred from a gaseous heat transfer fluid containing oxidants to a fluid containing combustible components, as well as to provide a method for operating a system in which heat can be transferred from a gaseous heat transfer fluid containing oxidants to a combustible one Fluid containing components is transferred, which avoids accidents.

This task is solved by a system with the features of claim 1 and a method with the features of claim 17. Advantageous embodiments and further developments of the invention are specified in the dependent claims.

A system according to the invention has a line for an oxidant-containing gaseous heat transfer fluid, in which a heat exchanger for transferring heat from the oxidant-containing gaseous heat transfer fluid to a fluid containing combustible components is arranged. The heat exchanger has a heat exchanger inlet through which the oxidant-containing gaseous heat transfer fluid can be fed from the line into the heat exchanger. The heat exchanger has a heat exchanger outlet through which the oxidant-containing gaseous heat transfer fluid can get back into the line after flowing through the heat exchanger. The system contains a device for triggering combustion of heat transfer fluid mixed with the fluid containing combustible components in the line for the oxidant-containing gaseous heat transfer fluid.

The invention is based on the idea that in a system in which heat from a gaseous heat transfer fluid containing oxidants is transferred to a Fluid containing combustible components is transferred as a further heat transfer fluid, leaks in a heat exchanger can be accepted, which can lead to an explosive atmosphere being created if an explosion is avoided and/or locally limited by controlled combustion of the explosive atmosphere in the system. One idea of the invention is, in particular, to prevent an explosive gas mixture from accumulating and spreading in the system by controlled ignition and oxidation at one point or at several points in a system.

The fluid containing flammable components can, for example, come from an ORC system. However, it may be expedient to use the system in further design variants for air pre-purging of an exhaust tract in internal combustion engines, gas turbines, thermal exhaust air purification systems and the like, in particular in all applications and processes in which a flammable or explosive mixture of substances is exposed to disruptive influences within spatially limited apparatus, containers , pipelines and the like can occur.

The device for triggering combustion advantageously has an ignition source for providing ignition energy, which can trigger a, preferably controlled, combustion of heat transfer fluid mixed with the fluid containing combustible components in the line for the oxidant-containing gaseous heat transfer fluid. It is advantageous if the ignition source is kept in an operating state during operation of the system that ensures that any ignitable gas that comes into contact with the ignition source is ignited immediately.

The ignition source is preferably arranged in the line for the oxidant-containing gaseous heat transfer fluid, preferably downstream of the heat exchanger, ie in a section connected to the heat exchanger outlet the line for the gaseous heat transfer fluid containing oxidants. This measure ensures that the explosive gas in the system is ignited shortly after it has formed within it.

The ignition source expediently has a body with a contact surface to the oxidant-containing, gaseous heat transfer fluid. It is advantageous if the ignition source has a heating device for heating the body. This allows the contact surface to be heated to a predetermined ignition temperature. In order to ensure reliable ignition of the mixture, it is advantageous if the body or the contact surface of the body reaches a temperature at any time which is above the ignition temperature of a mixture of the oxidant-containing gaseous heat transfer fluid and fluid containing flammable components.

The ignition source can have an ignition electrode, such as is used, for example, as a glow igniter in wood-burning stoves. Preferably the body is a ceramic body. A ceramic body can permanently withstand high temperatures, especially temperatures above the ignition temperature. This makes it suitable for continuous operation.

The system preferably contains a sensor for monitoring the temperature of the contact surface of the body of the ignition source. The sensor expediently has at least one thermal sensor thermally coupled to the body of the ignition source. Such a thermal sensor makes it possible to monitor the ignition source or the body of the ignition source. If the temperature falls below a temperature limit, a warning signal can then be issued, for example.

It is advantageous if the section of the line for the oxidant-containing, gaseous heat transfer fluid connected to the heat exchanger outlet and/or the section of the line connected to the heat exchanger inlet contains a pressure relief device that responds to a predetermined overpressure. By the device for triggering combustion of heat transfer fluid mixed with the fluid containing combustible components in the line causes a burn-off of a combustible gas atmosphere in the line in a burn-off section spaced from the heat exchanger and the pressure relief device for reducing a burn-off caused by the burn-off of a flammable gas atmosphere If the pressure increase caused in the combustion section is designed, it can be achieved that the system is not damaged when combustion is triggered by the ignition source.

Preferably, in the device for triggering combustion of heat transfer fluid mixed with the fluid containing combustible components, there are means which serve to detect a composition of the oxidant-containing gaseous heat transfer fluid after the heat exchanger outlet for the oxidant-containing gaseous heat transfer fluid.

The device for triggering combustion of heat transfer fluid mixed with the fluid containing combustible components in the line for the oxidant-containing gaseous heat transfer fluid expediently contains a control assembly which is designed for adjusting the temperature of the contact surface depending on a signal from the sensor for monitoring the temperature . This can ensure that the temperature of the contact surface corresponds at least to the ignition temperature. If the sensor detects a temperature below the ignition temperature, it is advisable to provide a warning signal or emergency stop signal at an interface to a control center in the system.

The fluid containing flammable components can be, for example, a Rankine Cycle (RC) working medium, in particular an ORC working medium. By routing the working medium in an RC or ORC working medium circuit, which contains a steam turbine as well as a condenser and a pump, heat from the oxidant-containing gaseous heat transfer fluid can be converted into mechanical energy, for example in order to convert this into electrical energy.

In the present case, an RC system (RC = Rankine Cycle) is to be understood as meaning a system in which a thermodynamic cycle is carried out using a working medium, e.g. B. water or water vapor, heat is converted into mechanical energy.

In the present case, an ORC system (ORC = Organic Rankine Cycle) is to be understood as meaning an RC system with a working fluid circuit, which contains an organic medium, e.g. ethylbenzene, pentane, butane, toluene, silicone oil or ammonia, the evaporation temperature of which is at atmospheric pressure can be lower than the evaporation temperature of water. In an ORC system, the work fluid is pressurized. The ORC system usually contains a pump for this. The pressurized working fluid is then heated in an evaporator. The working fluid is evaporated or overheated. The evaporated or overheated working fluid is then fed to a steam turbine. Here it is expanded to a low pressure while generating mechanical energy and then condensed. In the working fluid circuit of the ORC system, the working fluid is then pressurized again and fed back to the evaporator, where it is heated again and then evaporated again. It should be noted that media whose evaporation temperature is higher than that of water can also be used as working fluid in an ORC system. ORC systems can be used advantageously for generating mechanical or electrical energy from heat, particularly when the available temperature gradient between a heat source and a heat sink is too low to operate a heat engine, such as a turbine, with steam.

It is advantageous if a heat engine heat exchanger is arranged in the line in a section of the line connected to the heat exchanger inlet for the oxidant-containing gaseous heat transfer fluid, which is used to transfer heat from the oxidant-containing gaseous heat transfer fluid serves as a heat engine working medium for a heat engine. In this way, the heat of the heat transfer fluid in the line can be used in temperature ranges in which no heat is exchanged in the heat exchanger because there is a risk that the fluid containing flammable components will be damaged. The heat engine can be, for example, a Stirling engine.

A method according to the invention is used to operate a system with a line for an oxidant-containing gaseous heat transfer fluid, in which a heat exchanger for transferring heat from the oxidant-containing gaseous heat transfer fluid to a fluid containing combustible components is arranged, so that the oxidant-containing gaseous heat transfer fluid passes through the heat exchanger Heat exchanger input for the oxidant-containing gaseous heat transfer fluid can flow through to a heat exchanger output for the oxidant-containing gaseous heat transfer fluid. A controlled combustion of the oxidant-containing, gaseous heat transfer fluid in the line is triggered when it is mixed with the fluid containing flammable components.

The invention is explained in more detail below with reference to the exemplary embodiments shown schematically in the drawing.

Fig. 1

eine Anlage für das Speichern von elektrischer Energie,

Fig. 2

einen Abschnitt einer Leitung mit einem Wärmetauscher und mit einer Einrichtung für das Auslösen einer Verbrennung in der Anlage,

Fig. 3

einen Querschnitt der Einrichtung für das Auslösen einer Verbrennung in der Anlage entlang der Linie III - III aus Fig. 2;

Fig. 4

einen perspektivischen Längsschnitt der Leitung entlang der Linie IV - IV aus Fig. 3; und

Fig. 5

eine Steuerbaugruppe für das Einstellen der Temperatur der Kontaktfläche von Zündquellen in der Einrichtung für das Auslösen einer Verbrennung.

Show it:

Fig. 1

a system for storing electrical energy,

Fig. 2

a section of a line with a heat exchanger and with a device for triggering combustion in the system,

Fig. 3

a cross section of the device for triggering combustion in the system along line III - III Fig. 2 ;

Fig. 4

a perspective longitudinal section of the line along line IV - IV Fig. 3 ; and

Fig. 5

a control assembly for adjusting the temperature of the contact surface of ignition sources in the device for initiating combustion.

The ones in the Fig. 1 The system 10 shown is used to store electrical energy, which is generated, for example, by a wind turbine. The system 10 contains a line system 12 with a first line branch 13, in which a heating device 14 is arranged, and with a second line branch 15, in which a heat accumulator 16 is located. The heat storage 16 is designed to absorb an amount of heat Q. In the system 10 there is a line 18 which communicates with the line system 12. The line system 18 contains hot air lines which are designed as internally insulated channels, for example rectangular channels. The internal insulation preferably consists of a compacted fiber material, for example in the form of mats. These mats are elastic and can be deformed.

A heat exchanger 20 is arranged in the line 18 and is used to transfer heat from a heat transfer fluid carried in the line system 12 and in the line 18 communicating therewith to the working medium in an ORC system 22. The heat transfer fluid carried in the line system 12 and in the line 18 is air. The heat transfer fluid is therefore gaseous and, due to the oxygen in the air, particularly contains oxidants. The heat transfer fluid in the line system 12 can be heated in the heating device 14 with electrical current. By passing heat transfer fluid heated by means of the heating device 14 through the heat accumulator 16, it is possible to release the heat contained therein to the heat accumulator 16. The system 10 contains a heat engine 24 designed as a Stirling engine and has a heat engine heat exchanger 26. In the system 10, heat can be transferred from the heat transfer fluid the line system 12 and the line 18 communicating with it are transferred to a working fluid of the heat engine 24 by means of the Stirling engine heat exchanger 26. In the system 10 there is a heat transfer fluid fan 28, which is used to convey the heat transfer fluid through the line system 12 and line system 18. The system 10 has a first bypass line 30 through which heat transfer fluid can be guided past the heat engine heat exchanger 26 into the line 18. In addition, there is a recirculation line 32 in the system with a recirculation heat transfer fluid delivery fan 34, which makes it possible to return heat transfer fluid guided through the heat exchanger 20 to a section of the line 18 arranged between the heat exchanger 20 and the Stirling engine heat exchanger 26.

The ORC system 22 has an evaporator 36 and has a condenser 38. The evaporator 36 is fed with heat which is transferred from the heat transfer fluid in the line system 12 to the working fluid in the ORC system 22 by means of the heat exchanger 20. The condenser 38 in the ORC system 22 transfers the heat of condensation of the working fluid to the heat transfer fluid. The working fluid in the ORC system 22 contains flammable components. For example, the working fluid can be ethylbenzene. In the ORC system 22 there is a working fluid pump 40 which moves the working fluid condensed in the condenser 38 to the evaporator 36 in a working fluid circuit 42. The ORC system 22 has an engine designed as a turbine 44, which receives vaporous working fluid from the evaporator 36 on its pressure side. The working fluid in the ORC system expanded in the turbine 44 is fed to the condenser 38 through a heat exchanger 46. In the heat exchanger 46, heat from the working medium expanded in the turbine 44 is transferred to the working fluid conveyed from the condenser 38 into the heat exchanger 20 by means of the compressor 40. The turbine 44 in the ORC system 22 serves as a drive for a generator 47, which is designed here for an electrical power P _EL ≈ 50 kW. So that the flow of the in the system 10 by means of the heat transfer fluid fan 28 conveyed heat transfer fluid can be adjusted through the first line branch 13, the second line branch 15 and the line 18, there are several flow control means 48 in the line system 12 and in the bypass line 30.

The Fig. 2 shows a section of the line 18 with the heat exchanger 20. The line 18 is a pipe with a pipe axis 49, which has a circular pipe cross section perpendicular to the pipe axis 49. The line 18 can be, for example, an externally insulated, round steel pipe.

The heat exchanger 20 has a heat exchanger inlet 50 through which the heat transfer fluid can be fed from the line 18 into the heat exchanger 20 in the direction of the arrow 19. The heat exchanger 20 has a heat exchanger outlet 52, through which the heat transfer fluid, after flowing through the heat exchanger 20, returns to the line 18, in which it flows in the direction of the arrow 21.

The working fluid with the combustible components contained therein circulating in the ORC system 22 through the working fluid circuit 42 has an excess pressure compared to the oxidant-containing gaseous heat transfer fluid in the heat exchanger 20 during system operation. The excess pressure means that if there is a leak in the heat exchanger 20, the heat transfer fluid in the system 10 cannot get into the working fluid circuit 42 of the ORC system 22. However, due to the overpressure of the working fluid of the ORC system 22, there is fundamentally the possibility that working fluid of the ORC system 22 can enter the line 18 and the line system 12 of the system 10 if a leak occurs at a leak point 54 in the heat exchanger 20.

If working fluid of the ORC system 22 containing flammable components is in the system with gaseous heat transfer fluid containing oxidants 10 mixed, there is a risk that a flammable gas atmosphere will arise in the line 18 and in the line system 12 of the system 10, which can ignite or even explode, if necessary.

In order to prevent a flammable gas atmosphere 56 from spreading from the heat exchanger 20 into the line 18 when a leak occurs in the heat exchanger 20 in the system, the system 10 contains a device 58 for triggering combustion of fluid containing the flammable components mixed heat transfer fluid in the line 18, which causes the combustible gas atmosphere in the line 18 to burn off in the direction of the arrow 21 at a distance A from the device in a burn-off section 60. The distance A is as small as possible, but chosen to be large enough to ensure that the medium containing oxidizing agents and the combustible medium are mixed.

The Fig. 3 is a cross section of the device 58 for triggering combustion in the system 10 along line III - III Fig. 2 . In the Fig. 4 is a perspective longitudinal section of the line along line IV - IV Fig. 3 shown.

The device 58 for triggering combustion in the system 10 has a first ignition source 62, a second ignition source 64 and a third ignition source 66, each of which is accommodated on a connector 67 fixed to the pipeline wall 65 and projecting into the interior of the line 18 . The connection piece that accommodates the respective ignition source 62, 64, 66 is a gas-tight ignition source holding device which ensures that the gaseous heat transfer fluid from the inside of the line 18 cannot escape to the outside at the connection piece.

Each ignition source 62, 64, 66 has an ignition electrode 68 with a cylindrical ceramic body projecting into the line 18 and having a contact surface 70 for the heat transfer fluid flowing in the line. In the ignition electrode 68 there is an ignition electrode heating device 72 and a thermal sensor 74 which is thermally coupled to the cylindrical body. The ignition electrode heating device 72 and the thermal sensor 74 are connected to electrical lines 75, which in which the respective ignition source 62, 64, 66 receiving nozzle 67 run. The ignition electrode 68 of each ignition source 62, 64, 66 has the technical function of a glow element that can ignite a combustible gas atmosphere in its surroundings.

The ignition sources 62, 64, 66 project in the direction of the cylinder axis 76 of their ignition electrode 68 into the interior of the line 18, which is designed as a pipeline. The cylinder axes 76 of the ignition electrodes 68 of the ignition sources 62, 64, 66 have a common intersection point lying on the pipeline axis 49 and lie in a plane perpendicular to the pipeline axis 49. The cylinder axes 76 of adjacent ignition sources 62, 64, 66 enclose the angle α = 120 °. The cylinder axis 76 passes through the center of gravity 78, 80, 82 of a cross-sectional area circle segment 84, 86, 88 of the line 18 in the ignition electrode 68 of each ignition source 62, 64, 66, which has the segment angle α ₈₄ = α ₈₆ = α ₈₈ = 120 ° has. This ensures that the ignition sources 62, 64, 66 do not generate excessive flow resistance for the gaseous heat transfer fluid flowing through the line 18. Here, a free flow of the oxidant-containing gaseous heat transfer fluid is made possible.

Each ignition source 62, 64, 66 is protected against the flow in the direction of arrow 21 on its side facing the flow direction for the heat transfer fluid in line 18 by a shielding element 90 designed as a perforated plate. This ensures that any ignitable mixture that may be present comes into direct contact with the ignition sources 62, 64, 66 comes and is ignited. The ignition electrode 68 of an ignition source does not touch the shielding element 90.

The flow around the contact surface 70 of the ignition electrode 68 of each ignition source 62, 64, 66 with oxidant-containing gaseous heat transfer fluid causes continuous cooling of the contact surface. In order to ensure that the temperature of the contact surface 70 does not fall below the ignition temperature Tz, the ignition electrode heating device 72 must enable a correspondingly high heating output for heating the ignition electrode 68 of each ignition source 62, 64, 66.

The shielding element 90 assigned to each ignition source 62, 64, 66 in the device 58 for triggering combustion in the system 10 increases the residence time for the heat transfer fluid carried in the line 18, since it locally reduces the flow velocity for the heat transfer fluid. The result is that with a given heat input from the ignition electrode 68 into the heat transfer fluid via the contact surface 70, the temperature of the heat transfer fluid in the area of the contact surface increases. By means of the shielding elements 90, it is therefore possible to ignite heat transfer fluid mixed with the combustible components of the ORC working fluid at an ignition temperature T _z of the contact surface 70, which is lower than that, by heating the ignition electrode 68 of each ignition source 62, 64, 66 required ignition temperature T _z of the contact surface 70 without shielding by means of a shielding element.

The shielding element 90 is fixed to the connection piece 67 which accommodates the respective ignition source 62, 64, 66. The shielding element 90 has the shape of a semi-cylindrical tube with a cylinder axis which coincides with the cylinder axis 76 of the ignition electrode 68. The shielding element 90 extends over the entire length of the ignition electrode 68 of an ignition source 62, 64, 66 in the direction of the cylinder axis 76 of the body 68 and beyond. It has a radius R, which is approximately the diameter D of an ignition electrode 68 corresponds. The shielding element 90 surrounds an ignition electrode 68 radially at an arc angle β = 180 °. The shielding element 90 has edges parallel to a cylinder axis 76 of the body, which lie in a common cross-sectional plane of the line 18 perpendicular to the pipeline axis 49.

The shielding element 90 has a plurality of openings and causes the ignition electrode 68 of an ignition source 62, 64, 66 to be shielded against direct flow of gaseous heat transfer fluid. However, due to the openings in the shielding element 90, a possible ignitable mixture in the line 18 can reach the contact surface 70 of the ignition electrode 68 and thus be ignited.

The ignition electrode heating device 72 in the ignition electrode 68 of each ignition source 62, 64, 66 makes it possible to adjust the temperature T of the contact surface 70 of the ignition electrode 68 to an ignition temperature T _z required for igniting a gas mixture in the line 18 in such a way that: $$\mathrm{T}\gg {\mathrm{T}}_{\mathrm{Z}}$$

In the present case, the ignition temperature T _z of the ORC working fluid is ethylbenzene $${\mathrm{T}}_{\mathrm{Z}}\approx 430°\mathrm{C}$$

lässt sich erreichen, dass in der Leitung 18 mit dem ORC-Arbeitsmittel Ethylbenzol versetztes oxidationsmittelhaltiges gasförmiges Wärmeträgerfluid an den Zündquellen 62, 64, 66 entzündet werden kann.By ensuring that the temperature T of the contact surface 70 of the body 68 applies: $$\mathrm{T}\approx 900°\mathrm{C}$$

It can be achieved that gaseous heat transfer fluid containing oxidizing agents containing the ORC working fluid ethylbenzene can be ignited at the ignition sources 62, 64, 66 in line 18.

If, as a result of a leak in the heat exchanger 20, a combustible gas atmosphere arises in the line 18 in a section connected to the heat exchanger outlet 52, this at least partially flows around the contact surface 70 of the ignition electrode 68 of the ignition sources 62, 64, 66. Because the temperature T a contact surface 70 exceeds the ignition temperature T _z , the gas atmosphere is ignited here and then burned off in the burn-off section 60 of the line 18. In this way it is ensured that flammable components are removed from the heat transfer fluid in the line 18 and in the line system 12.

Since the ignition of a gas atmosphere in the line 18 results in a local volume expansion and, as a result, an increase in pressure, the line 18 has a pressure relief device 92 with an opening 94 in the sections connected to the heat exchanger outlet 52 and the heat exchanger inlet 50 the pipe wall 65 has a gas-tight sealing rupture disk 96. The pressure relief device 92 is an overpressure protection and responds to a predetermined overpressure in the line 18. If the pressure increases in the section of the line 18 connected to the heat exchanger inlet 50 or the heat exchanger outlet 52, which exceeds an overpressure threshold value, which can be, for example, 100 mbar, the rupture disk 96 is destroyed and thus the opening 94 in the Pipe wall 65 released to a discharge line 98. This ensures that assemblies and elements 10 in the piping system 12 and the line 18 of the system 10 do not experience excessive mechanical stress when a gas atmosphere is ignited in the section of the line 18 connected to the heat exchanger outlet 52.

That section of the line 18 of the line system 12 which contains the device 58 for triggering combustion and which is arranged between the devices for pressure relief 92, which, viewed in the flow direction for the heat transfer fluid corresponding to arrow 19, is located in front of the heat exchanger inlet 50 and on the other hand behind the heat exchanger outlet 52 of the heat exchanger 20 is therefore such designed so that they can withstand the mechanical stress caused by explosions, burns or deflagrations due to overpressure pressure surges without being damaged if the overpressure dp of the pressure surges does not exceed a value of, for example, dp = 200mbar.

An explosion area is thus created which contains the ignition device 58, the combustion section 60, the heat exchanger 20 and the above-mentioned section of the line 18 of the line system 12. If the rupture disks 96 in the pressure relief devices 92 are destroyed due to an explosion, combustion gases are released through the then released openings 94 so that they cannot spread into the system 10.

The ignited gas atmosphere can exit the line 18 through the openings 94 and be released through the discharge line 98, for example over a hall roof. The outlet of a discharge line 98 is preferably arranged in such a way that a flash flame emerging from the discharge line, in particular in a straight line, can emerge within a radius of approximately 6 m without igniting objects in the vicinity of the outlet.

It is advantageous if the outlet of the outlet line is protected against the ingress of rainwater, snow or the like, for example by a valve, a cap, a closure, or the like. It should be noted that such a pressure relief device 92 in the system 10 can also be provided in other sections of the system 10, for example in the recirculation line 32.

The Fig. 5 shows a control assembly 100 with the ignition sources of the device for triggering combustion. The control module 100 is used to set an ignition temperature T _Z on the contact surface 70 of the ignition electrode 68 of the ignition sources 62, 64, 66. The heating device 74 in the ignition electrodes 68 is powered by electrical current, for example from a transformer 102 or operated by a thyristor powered from a low voltage subsupply. The ignition electrode heating devices 72 of the ignition sources 62, 64, 66 are connected in parallel with one another. The temperature T on the contact surface 70 of the ignition electrode 68 of the ignition sources 62, 64, 66 is monitored by means of a thermal sensor 74. The thermal sensor 74 measures the temperature of the contact surface 70 of the body of an ignition electrode 68. The thermal sensor 74 is arranged in the body of an ignition electrode 68. Alternatively, the thermal sensor 74 can be applied to the contact surface 70. It should be noted that the temperature at the contact surface 70 of the body of an ignition electrode 68 can be up to 1300 ° C.

The measurement signals from the thermal sensors 74 are fed to the control module 100 and converted there into temperature values. The control module 100 monitors these temperature values and compares them with a predetermined minimum temperature T _min , which can be approximately 900 ° C, for example.

The control module 100 is set up to provide a warning signal at an interface 104 and an emergency stop signal at an interface 106 for a control center of the system 10. The warning signal is provided when the measurement signals from one of the thermal sensors assigned to the ignition sources 62, 64, 66 correspond to temperature values that fall below the predetermined minimum temperature T _min . The warning signal carries the information that the function of the device 58 for triggering combustion of heat transfer fluid mixed with the fluid containing flammable components in the line 18 is impaired.

The emergency stop signal is provided at the interface 104 when two of the thermal sensors assigned to the ignition sources 62, 64, 66 detect temperature values that fall below the predetermined minimum temperature T _min . By means of the emergency stop signal, the system 10 can be put into an operating state in which the spread of any ignitable mixture that may be present via the line system 12 of the system 10 is avoided.

In particular, spread to the hot parts of the system 14 and 16 is prevented. This is done by switching off the heat transfer fluid fan 28 and the recirculation heat transfer fluid delivery fan 34 and by closing quick-closing flaps 51, which stop the flow of heat transfer fluid through the heat exchanger 20. This emergency stop operating state is ended, for example, when the emergency stop signal 104 is no longer present and a leak test of the heat exchanger 20, for example by evacuation, has been carried out and preferably no leakage is detected.

It should be noted that in a first alternative embodiment of the system 10, the control module 100 can be designed to regulate the heating devices 74 in the ignition electrodes 68 to a predetermined temperature value depending on the temperature detected by a thermal sensor 74.

In addition, it should be noted that in a second alternative embodiment of the system 10, the control assembly 100 can be designed to send measurement signals to a device with sensors for detecting the chemical composition of the heat transfer fluid in the section of the line 18 connected to the heat exchanger outlet 52 obtained and evaluated in order to set the heating devices 74 in the ignition electrodes 68 for an ignition temperature that is adapted to the chemical composition of the heat transfer fluid in the system 10.

The system 10 described above can assume at least three operating states:

First operating state

und $$500°\mathrm{C}\le {\mathrm{T}}_{\mathrm{o}}\le 1500°\mathrm{C},\mathrm{vorzugsweise}{\mathrm{T}}_{\mathrm{o}}\approx \mathrm{1000}°\mathrm{C}\mathrm{.}$$

In a first operating state, the heat storage 16 is loaded with heat. Here, the heat transfer fluid heated by the heating device 14 flows through the heat storage 16 with a mass flow m. The heating device 14 heats the heat transfer fluid here from a temperature T _u to a temperature T _o , whereby, for example: $$0°\le {\mathrm{T}}_{\mathrm{u}}\le 350°\mathrm{C},\mathrm{preferably}{\mathrm{T}}_{\mathrm{u}}\approx \mathrm{270}°\mathrm{C}$$

and $$500°\mathrm{C}\le {\mathrm{T}}_{\mathrm{O}}\le 1500°\mathrm{C},\mathrm{preferably}{\mathrm{T}}_{\mathrm{O}}\approx \mathrm{1000}°\mathrm{C}\mathrm{.}$$

When the heat transfer fluid flows through the heating device 14, a pressure loss of dp occurs.

After the heat transfer fluid flows through the heating device 14, the line system 12 leads the heat transfer fluid to the heat storage 16. During this supply from the heating device 14 to the heat storage 16, the heat transfer fluid loses energy, which is expressed in a temperature reduction dT of the oxidant-containing gaseous heat transfer fluid. By releasing heat from the heat transfer fluid onto the heat storage 16, the latter is loaded. Due to the heat given off by the heat transfer fluid to the heat storage 16, its temperature T drops to T ≈ 260 ° C after flow through the heat storage. When the heat transfer fluid flows through the heat storage 16, the oxidant-containing gaseous heat transfer fluid experiences a pressure loss dp.

When the heat transfer fluid is supplied from the heat storage 16 through the heat transfer fluid blower 28 to the heating device 14, flow work is absorbed by the heat transfer fluid, which is expressed in a temperature reduction dT of the oxidant-containing gaseous heat transfer fluid. The oxidant-containing gaseous heat transfer fluid then enters the heating device 14 again at a reduced temperature. The cycle now begins again until the heat storage 16 has absorbed the desired amount of heat Q.

Second operating state

In a second operating state, heat is removed from the heat storage 16, ie the heat storage 16 is discharged.

Here, heat is taken from the heat storage 16 in the system 10 in order to convert it into electrical energy. In the second operating state, the flow paths for the heat transfer fluid in the line system 12 are set so that heat transfer fluid from the heat storage 16 with a temperature T with 600 ° C ≤ T ≤ 975 ° C and with a mass flow m ≈ 0.4 kg / s initially passes through the heat engine heat exchanger 26 and then through the heat exchanger 20. The heat engine heat exchanger 26 receives the heat transfer fluid at a temperature T ≈ 950 ° C due to the pipe heat losses in the pipe system 18. To operate the Stirling engine, heat is removed from the oxidant-containing gaseous heat transfer fluid at a heat rate Q̇ ≈ 30 kW, which then results in a temperature drop dT of the oxidant-containing gaseous heat transfer fluid of dT ≈ 150 K. The oxidant-containing gaseous heat transfer fluid therefore has a temperature T ≈ 800 ° C downstream of the heat engine heat exchanger 26. In this operating state, the Stirling engine delivers an electrical power P _el ≈ 7.5 kW. A mass flow of the oxidant-containing gaseous heat transfer fluid of approximately 0.2 kg/s is used.

Optionally, the heat engine heat exchanger 26 can be partially or completely bypassed using the bypass line 30. The bypass line 30 is activated or interrupted via a closing valve 48. In the system 10, approximately half, i.e. approximately 0.2 kg/s, of the mass flow m of the oxidant-containing gaseous heat transfer fluid flows through the bypass line 32 and thus bypasses the heat engine heat exchanger 26, the other half is sent to the heat engine 24 via the heat engine heat exchanger 26 supplied. Depending on the desired operating point of the heat engine 24 and/or heat engine 22, the bypass line 30 or the closing valve 48 and the heat transfer fluid fan 28 can be used Mass flow can be adjusted so that the correspondingly necessary enthalpy flow of the oxidizing agent-containing gaseous heat transfer fluid is present.

Through the recirculation line 32, a portion, in particular between 0% and 100%, preferably between approximately 20% and approximately 80%, of the total mass flow m of the already cooled, oxidant-containing gaseous heat transfer fluid emerging from the heat exchanger 20 can be fed again to the heat exchanger 20. This allows the inlet temperature of the oxidant-containing gaseous heat transfer fluid to be regulated at the heat exchanger inlet 50.

The portion of the oxidant-containing gaseous heat transfer fluid that does not flow through the recirculation line 32 has a temperature of approximately 200 ° C and is moved back to the heat storage 16 via the heat transfer fluid blower 28. The cycle now begins again until the heat accumulator 16 has released the desired amount of heat Q.

In the second operating state, when starting up the ORC system 22 in the system 10, it is preferably checked for safety reasons whether the ignition electrodes 68 of the ignition sources 62, 64, 66 are functioning properly. For this purpose, the temperature values of the thermal sensors 74 are monitored in the control module 100. If a faulty function is detected in only one of the three ignition sources, an error message is preferably output to the control center of the system 10.

Third operating state

In a third operating state, the system comes to a standstill. Here the flow control devices 48, ie flaps, closing valves and the like, are closed so that as little heat as possible can escape from the system 10, in particular from the heat accumulator 16. It may be useful that individual flow control devices 48 are opened to allow the heat transfer fluid blowers 28 to run out. In the third operating state, the system 10 is conveniently operated when neither energy is to be supplied to the heat storage 16 nor energy is to be removed from the heat storage 16.

In summary, the following preferred features of the invention should be noted in particular: A system has a line 18 for an oxidant-containing gaseous heat transfer fluid, in which a heat exchanger 20 is arranged for exchanging heat between the oxidant-containing gaseous heat transfer fluid and a fluid containing flammable components. The heat exchanger 20 has a heat exchanger inlet 50 through which the oxidant-containing gaseous heat transfer fluid can be fed from the line 18 into the heat exchanger 20. The heat exchanger 20 has a heat exchanger outlet 52 through which the oxidant-containing gaseous heat transfer fluid can get back into the line 18 after flowing through the heat exchanger 20. The system contains a device 58 for triggering combustion of heat transfer fluid mixed with the fluid containing combustible components in the line 18 for the oxidant-containing gaseous heat transfer fluid.

Reference symbol list

10

Attachment

12

Piping system

13

first line branch

14

Heating device

15

second line branch

16

Heat storage

18

Line

20

Heat exchanger

22

ORC system

24

Heat engine

26

Heat engine heat exchanger

28

Heat transfer fluid blower

30

Bypass line

32

Recirculation line

34

Recirculation heat transfer fluid conveyor fan

36

Evaporator

38

capacitor

40

Working fluid pump

42

Work fluid circulation

44

turbine

46

Countercurrent heat exchanger

47

generator

48

Flow control means

49

Pipe axis

50

Heat exchanger inlet

51

Quick-closing flap

52

Heat exchanger outlet

54

Leak point

56

gas atmosphere

58

Device for initiating combustion

60

burn section

62

first ignition source

64

second ignition source

66

third ignition source

65

Pipe wall

67

Support

68

ignition electrode

70

Contact surface

72

Ignition electrode heater

74

Thermocouple

75

electric lines

76

Cylinder axis

78, 80, 82

Center of gravity

90

Shielding element

92

Pressure relief device

94

opening

96

rupture disk

98

discharge line

100

Control assembly

102

transformer

104, 106

interface

Claims (18)

System (10) with a line (18) for an oxidant-containing gaseous heat transfer fluid, in which a heat exchanger (20) for exchanging heat between the heat transfer fluid and a fluid containing flammable components is arranged, which has a heat exchanger inlet (50), through which the heat transfer fluid can be fed from the line (18) into the heat exchanger (20), and which has a heat exchanger outlet (52) through which the heat transfer fluid returns to the line (18) after flowing through the heat exchanger (20). can,
marked by
a device (58) for triggering combustion of heat transfer fluid mixed with the fluid containing combustible components in the line (18). Plant according to claim 1, characterized in that the device (58) for triggering combustion has an ignition source (62, 64, 66) for providing ignition energy. System according to claim 2, characterized in that the ignition source (62, 64, 66) is arranged in a section of the line (18) connected to the heat exchanger outlet (52). System according to claim 2 or 3, characterized in that the ignition source (62, 64, 66) has a body with a contact surface (70) to the oxidant-containing gaseous heat transfer fluid and has a heating device (72) for heating the body (68), to heat the contact surface (70) to a predetermined ignition temperature. System according to claim 4, characterized in that the body is a ceramic body. System according to claim 4 or 5, characterized by a sensor for monitoring the temperature of the contact surface (70) of the body of the ignition source (62, 64, 66). System according to claim 6, characterized in that the sensor has at least one thermal sensor (74) thermally coupled to the body of the ignition source (62, 64, 66). Plant according to one of claims 6 or 7, characterized in that the device (58) for triggering combustion of heat transfer fluid mixed with the fluid containing combustible components has means for detecting a composition of the oxidant-containing gaseous heat transfer fluid after the heat exchanger outlet (52). which has gaseous heat transfer fluid containing oxidizing agents. System according to claim 8, characterized in that the device (58) for triggering combustion of heat transfer fluid mixed with the fluid containing combustible components in the line (18) for the oxidant-containing gaseous heat transfer fluid contains a control assembly (100) which is used for the adjustment the temperature of the contact surface (70) is designed depending on a signal from the sensor for monitoring the temperature. System according to one of claims 3 to 9, characterized in that the section of the line (18) for the oxidant-containing gaseous heat transfer fluid connected to the heat exchanger outlet (52) and/or the section of the line connected to the heat exchanger inlet (50). (18) contains a pressure relief device (92) for the oxidant-containing gaseous heat transfer fluid. System according to one of claims 1 to 10, characterized in that the device (58) for triggering combustion of heat transfer fluid mixed with the fluid containing combustible components in the line (18) in a combustion section (60) spaced from the heat exchanger (20). ) causes a combustion of a combustible gas atmosphere in the line (18) and the pressure relief device (92) is designed to reduce a pressure increase caused by the combustion of a combustible gas atmosphere in the combustion section (60). Plant according to one of claims 1 to 11, characterized in that the fluid containing flammable components is an ORC working medium. Plant according to claim 12, characterized in that the ORC working medium is guided in an ORC working medium circuit which contains a turbine (44), in particular a steam turbine, as well as a condenser (38) and a compressor (40). System according to claim 13, characterized by a line system (12) communicating with the line (18), in which a heating device (14) and/or a heat accumulator (20) is arranged for heating gaseous heat transfer fluid containing oxidizing agents flowing through the heat exchanger (20). is. System according to claim 14, characterized in that in the line in a section of the line (18) connected to the heat exchanger inlet (50) for the oxidant-containing gaseous heat transfer fluid, a heat engine heat exchanger (26) is arranged, which is used for transferring heat from the oxidant-containing gaseous heat transfer fluid is arranged on a heat engine working medium for a heat engine (24). System according to claim 15, characterized in that the heat transfer fluid supplied to the heat engine heat exchanger (26) through the line (18) can be passed through the heat exchanger (20) for transferring heat to the ORC working medium. Plant according to claim 15 or claim 16, characterized in that the heat engine (24) is a Stirling engine. Method for operating a system (10) with a line (18) for an oxidant-containing gaseous heat transfer fluid, in which a heat exchanger (20) is arranged for exchanging heat between the heat transfer fluid and a fluid containing flammable components, so that the heat transfer fluid reaches the heat exchanger ( 20) can flow from a heat exchanger inlet (50) for the heat transfer fluid to a heat exchanger outlet (52) for the heat transfer fluid,
marked by
triggering a controlled combustion of the oxidant-containing gaseous heat transfer fluid in the line (18) when it is mixed with the fluid containing flammable components.

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