Patent Application
20180106551
The invention relates to a heat exchanger component and a heat exchanger system comprising a plurality of the heat exchanger components that control the temperature of a gas flow containing solid particles. The invention also relates to a device that includes such a heat exchanger system and produces a combustible product gas from carbon-containing input materials.
Gas flows that contain solid particles include flue gas produced by combustion systems, product gas streams generated by chemical reactors and also combustible product gas produced from carbon-containing solid particles. For example, combustible product gas is generated through wood gasification and coal gasification. The hot gas flows that include solid particles must generally be cooled. If this cooling is carried out in conventional liquid-gas heat exchangers, there is a danger that the solid particles will be partially deposited in the heat exchanger and thus will significantly reduce the efficiency of the heat transfer. Moreover, the operating time is reduced because the heat exchangers must periodically be cleaned.
Japanese patent JP H1162723A and European patent EP 1884634A2 describe heat exchangers for an exhaust. The heat exchanger for exhaust gas of Japanese patent application JP 2000111277A has cooling ribs in a longitudinal direction. Austrian patent AT 371591B discloses a heat exchanger, in particular for injection molding machines and die casting machines. The heat exchanger has a helical heat transfer body that can be heated or cooled. Heating elements and a coolant feed tube protrude into the hollow core of the helical heat transfer body.
United States patent application publication US 2008/0190593A1 discloses a heat exchanger that has helical guide plates with inner and outer parts. The helical guide plates are penetrated by tubes through which a heat exchange medium flows for heat exchange. U.S. Pat. No. 6,827,138 discloses a heat exchanger that has quadrant baffles arranged in the form of a helix.
A problem with these known heat exchangers is that the volume of the gas flow is reduced by cooling the gas flow in the heat exchanger component. The reduced gas flow also reduces the flow velocity. Consequently, the centrifugal forces in the helical gas stream are reduced, the thickness of the Prandtl boundary layer increases, and the heat transfer coefficient drops.
It is an object of the present invention to provide a heat exchanger component, and a heat exchanger system that includes such heat exchanger components, that pollutes less by controlling the temperature of gas flows and in particular by cooling gas flows that include solid particles, while also exhibiting a large heat transfer capacity. Moreover, it is also an object of the present invention to provide a device for producing a combustible product gas from carbon-containing input materials that includes such a heat exchanger system.
A heat exchanger component is disclosed that controls the temperature of the flow of gas that contains solid particles, such as a gas generated by a device that produces a combustible product gas from carbon-containing input materials. A heat exchanger system is also disclosed that includes a plurality of the heat exchanger components.
Gas flows that are mixed with solid particles occur in the form of flue gas and product gas streams. The hot gas flows that contain solid particles must generally be cooled. If this cooling is carried out in conventional liquid-gas heat exchangers, there is a danger that the solid particles will be partially deposited in the heat exchanger and thus significantly reduce the efficiency of the heat transfer. By designing the gas inlet and the gas outlet to enter and exit tangentially and transversely to the flow channel of the heat exchanger component, a helical shaped gas stream is generated inside the flow channel around the middle of the cylindrical main body of the heat exchanger component. The velocity of the gas flow is maintained by making the cross-sectional area of the gas outlet smaller than the cross-sectional area of the gas inlet so as to compensate for the reduced volume of the gas as it cools.
The high velocity of the gas flow is thereby maintained so that the Prandtl boundary layer on the inner side of the cladding of the cylindrical main body is comparatively thin. This significantly increases the heat transfer between the cladding and the environment because the outer side of the cladding releases more heat. Because the high velocity results in large centrifugal forces, the solid particles in the gas concentrate in a narrow region on the inner side of the cladding, and the probability of particle collisions and the caking of smaller particles into larger particles increases sharply. Larger solid particles are easier to separate using downstream filters. Due to the high flow velocity and the associated turbulent flow, the depositing of solid particles on the inner side of the cladding is prevented.
A heat exchanger component for cooling product gas generated from carbon-containing input materials includes a cylindrical main body, a rod-shaped component, a gas inlet and a gas outlet. The cylindrical main body has a circumferential cladding. An annular flow channel is formed in the cylindrical main body around the rod-shaped component, which extends axially in the cylindrical main body. The gas inlet and gas outlet are disposed towards opposite ends of the cylindrical main body. The gas inlet is tubular and enters the annular flow channel tangentially to the circumferential cladding and perpendicularly to the axial direction of the cylindrical main body. The velocity of the gas flow is maintained despite the decreasing volume as the product gas cools by making the cross-sectional area of the gas outlet smaller than that of the gas inlet.
In one embodiment, a helical shaped guide plate is disposed in the annular flow channel and has an outer circumferential edge that seals tightly against an inner surface of the circumferential cladding. The inner circumferential edge of the helical shaped guide plate fits tightly around the rod-shaped component. In another embodiment, the cylindrical main body is coaxially oriented inside an outer cylindrical container that forms a channel between the circumferential cladding and the outer cylindrical container. A heat transfer medium is disposed in the channel and transforms the heat exchanger component without the outer container from a gas-gas heat exchanger to a gas-liquid heat exchanger, which has a higher heat transfer performance.
A heat exchanger system includes multiple heat exchanger components. For example, a heat exchanger system with two heat exchanger components includes a first cylindrical main body with a first circumferential cladding and a second cylindrical main body with a second circumferential cladding. A first gas inlet and a first gas outlet are disposed towards opposite sides of the first cylindrical main body. The first gas inlet enters the first cylindrical main body tangentially to the first circumferential cladding. The cross-sectional area of the first gas inlet is larger than that of the first gas outlet. A second gas inlet and a second gas outlet are disposed towards opposite ends of the second cylindrical main body. The second gas inlet is connected to the first gas outlet and has the same cross-sectional area as that of the first gas outlet. The second gas inlet enters the second cylindrical main body tangentially to the second circumferential cladding. The cross-sectional area of the second gas inlet is larger than that of the second gas outlet.
A first rod-shaped component extends axially in the first cylindrical main body, and a second rod-shaped component extends axially in the second cylindrical main body. A first annular flow channel is formed around the first rod-shaped component in the first cylindrical main body, and a second annular flow channel is formed around the second rod-shaped component in the second cylindrical main body. The second annular flow channel has a cross-sectional area that is smaller than that of the first annular flow channel.
A gasifier device for producing a product gas from carbon-containing material includes a gasifier component whose diameter is smaller than the diameter of a gasifier container in which the gasifier component is coaxially positioned. The upper closed end of the gasifier component projects up and out of the gasifier container. A supply inlet is adapted to receive the carbon-containing material into the upper closed end of the gasifier component. An air supply inlet enters the gasifier component near the upper closed end and is used to feed combustion air into the gasifier component. A rotary grate is disposed in the lower portion of the gasifier container and is adapted to support the carbon-containing material. A product gas vent leads out of the gasifier container below the grate. The product gas generated from the carbon-containing material exits the gasifier container through the product gas vent.
A heat exchanger component includes a gas inlet, a gas outlet and a cylindrical main body. The gas inlet is connected to the product gas vent and enters the heat exchanger component tangentially to the cylindrical main body. Product gas containing solid particles, such as ash from the carbon-containing material, enters the heat exchanger component through the gas inlet. The cross-sectional area of the gas inlet is larger than the cross-sectional area of the gas outlet.
Other embodiments and advantages are described in the detailed description below. This summary does not purport to define the invention. The invention is defined by the claims.
The accompanying drawings, where like numerals indicate like components, illustrate embodiments of the invention.
Reference will now be made in detail to some embodiments of the invention, examples of which are illustrated in the accompanying drawing.
The cross-sectional area of the gas outlet 14 is made smaller than the cross-sectional area of the gas inlet 13 to account for the fact that the volume of the gas flow decreases as the gas flow cools in the heat exchanger component 10. The flow velocity of the gas flow 11 would decrease if the cross-sectional area and initial flow volume were maintained constant while the temperature of the gas flow 11 decreases. By making the cross-sectional area of the gas outlet 14 smaller than that of the gas inlet 13, the flow velocity at the gas outlet 14 is made to equal approximately the flow velocity at gas inlet 13.
The gas inlet 13 enters tangentially and transversely into an annular flow channel 15 of the cylindrical main body 16 of the heat exchanger component 10. The gas outlet 14 also exits the cylindrical main body 16 transversely and tangentially from the annular flow channel 15. The gas inlet 13 and the gas outlet 14 pass through the cylindrical outer cladding 17 of the main body 16. By allowing the gas flow 11 to enter the annular flow channel 15 tangentially, a screw-thread, cyclone or helical shaped gas stream is generated inside the flow channel 15 that travels in a helix around a rod-shaped member 18 oriented axially in the cylindrical main body 16.
The flow velocity of the gas flow 11 that includes solid particles 12 is very high in the vicinity of the gas inlet 13, which allows the Prandtl boundary layer 19 on the inner side 20 of the circumferential cladding 17 of the main body 16 to be comparatively thin. The Prandtl boundary layer 19 is compressed by the high centrifugal forces resulting from the high flow velocity. This significantly increases the heat transfer between the gas flow 11 and the cladding 17 such that the outer side 21 of the cladding 17 releases more heat to the environment. Because of the high centrifugal forces, the solid particles 12 also concentrate in a narrow region on the inner side 20 of the cladding 17, thereby sharply increasing the probability of particle collisions and the caking of smaller particles into larger particles. Larger solid particles are easier to separate using downstream filters. Finally, due to the high flow velocity and the associated turbulence of the flow, solid particles 12 are prevented from being deposited on the inner side 20 of the circumferential cladding 17, which would more likely occur with a laminar flow.
The disclosed configuration of the heat exchanger component 10 promotes the formation and maintenance of the desired helical gas flow 11 within the annular flow channel 15. Specifically, the heat exchanger component 10 is configured such that the gas inlet 13 and the gas outlet 14 lead into the cylindrical main body 16 tangentially and perpendicularly to the longitudinal direction of the cylindrical main body 16.
In another embodiment, a helical (screw-thread shaped) guide plate 22 is disposed in the cylindrical main body 16 and maintains a helical gas stream through the heat exchanger component 10. The helical shaped guide plate 22 may have one or more windings. A plurality of helical shaped guide plates may also be used. It is beneficial for the helical shaped guide plates to have one or just a few windings because the greater the number of windings, the more pressure of the gas stream is lost in the heat exchanger, which is undesirable. For this reason, it is advantageous to provide just one helical shaped guide plate per heat exchanger component 10.
By designing the gas inlet 13 and gas outlet 14 to open transversely and tangentially into the flow channel 15, a helical flow of gas is created inside the flow channel 15 that travels around the center rod-shaped component 18 of the main body 16. The helical shaped gas stream is maintained in the flow channel 15 by the helical shaped guide plate 22 that tightly surrounds the rod-shaped component 18 and extends outwards to the inner side 20 of the circumferential cladding 17.
The volume of the gas flow 11 decreases as the gas flow 11 in the heat exchanger component 10 cools, thereby also reducing the flow velocity. To compensate for the reduced flow velocity, the cross-sectional area 26 of the gas outlet 14 is made smaller than the cross-sectional area 27 of the gas inlet 13. The flow velocity at the gas inlet 13 can be made approximately equal to the flow velocity in the gas outlet 14 by sufficiently reducing the cross-sectional area 26 of the gas outlet 14 compared to that of the gas inlet 13.
The reduction in the volume of the gas flow 11 resulting from the heat extraction causes the flow velocity to drop between the gas inlet 13 and the gas outlet 14. In addition, as the centrifugal forces in the helical shaped gas flow 11 decrease with decreased flow velocity from the gas inlet 13 to the gas outlet 14, the heat transfer coefficient drops, and the thickness of the Prandtl boundary layer 19 increases, as shown in
The heat exchanger system 28 is formed by connecting the gas outlet 14 of the ith heat exchanger component to the gas inlet 13 of the (i+1)th heat exchanger component. Because the cross-sectional area of the gas outlet 14 of the ith heat exchanger component (also the gas inlet 13 of the (i+1)th heat exchanger component) is made smaller than the cross-sectional area of the gas inlet 13 of the ith heat exchanger component, the gas flow 11 is accelerated back to the original flow velocity. By maintaining the original high flow velocity, high centrifugal forces are again present in the region of the gas inlet 13 of the (i+1)th heat exchanger component, and the Prandtl boundary layer 19 is tightly pressed to the inner side 20 of the cladding 17 of the main body 16 of the (i+1)th heat exchanger component.
As the volume of the gas flow 11 decreases from cooling in successive downstream heat exchanger components of the heat exchanger system 28, the volume of the annular flow channel in each successive step of the heat exchanger system 28 is decreased in order to prevent the flow velocity from decreasing.
By using the heat exchanger system 28 in a device for producing a combustible product gas from carbon-containing input materials, the gas producing device becomes more efficient. For the same gas production, the size of the heat exchanger system can be smaller on account of the compactness of the design of the linked heat exchanger components.
A helical gas stream 33 is created in the annular flow channel 15 around the rod-shaped member 18 by orienting the gas inlet 13 tangentially into the annular flow channel 15. The cross-sectional area 34 of the annular flow channel 15 is constant between the gas inlet 13 and the gas outlet 14. In this way, the flow velocity v of the gas flow 11 containing solid particles 12 is sufficiently high in the vicinity of the gas inlet 13 so that the Prandtl boundary layer 19 on the inner side 20 of the cladding 17 of the main body 16 is comparatively thin, as shown in
Because heat is continuously withdrawn from the gas flow 11 through the cladding 17, the volume of the gas flow 11 is continuously reduced, while the mass flow remains constant. The reduction in the volume of the gas flow 11 reduces the flow velocity v, and consequently also the centrifugal forces of the gas flow 11. With reduced flow velocity v, the thickness of the Prandtl boundary layer 19 increases, and the heat transfer coefficient of the cladding 17 is reduced between the gas inlet 13 and the gas outlet 14. The increase in the thickness of the Prandtl boundary layer 19 from the gas inlet 13 towards the gas outlet 14 is illustrated in
The cross-sectional areas 34, 42 and 43 of the annular flow channels 15 of the three heat exchanger components 39, 40 and 41, respectively, are successively smaller. Due to the reduction of the cross-sectional areas 34, 42 and 43 from one heat exchanger component downstream to the next, the reduction of the volume of the gas flow 11 on account of the cooling is offset. By reducing the cross-sectional areas 26 of the gas outlets 14 of successive downstream heat exchanger components compared to the cross-sectional area 27 of the gas inlet 13 of each component, the flow velocity v at the gas inlet 13 of each downstream component is held constant, and the conditions of the centrifugal forces in each annular flow channel are approximately the same.
In
A tubular gasifier component 50 has a lower open end 51 and an upper closed end 52. The gasifier component 50 projects with its lower open end 51 down into the gasifier container 47. The closed end 52 of the gasifier component 50 protrudes out through the upper cover 48 of the gasifier container 47. The open end 51 of gasifier component 50 lies approximately at the middle of the gasifier container 47. A rotary grate 53 is disposed in the gasifier container 47 at a distance 54 below the open end 51 of the gasifier component 50. The rotary grate 53 is moved periodically by a motor 55 and a drive shaft 56 that penetrates through the lower cover 49 of the gasifier container 47.
The upper, closed end 52 of the gasifier component 50 is penetrated by a supply inlet 57 for carbon-containing input materials such as pourable biomass particles 58, an air supply inlet 59 through which combustion air 60 enters the gasifier container 47, and a level sensor 61 by which the level of biomass particles 58 in the cylindrical gasifier component 50 is determined and monitored. An inspection shaft 62 penetrates the outer wall of the gasifier container 47 at the level of the open end 51 of the gasifier component 50. The inspection shaft 62 is closed by a covering flange 63 that is part of a temperature measurement device 64. The temperature in the gasifier container 47 is monitored using the temperature measurement device 64. Access into the reactor vessel can be gained through the inspection shaft 62 in order to perform maintenance and cleaning work inside the reactor vessel during the standstill of the reactor.
The product gas 11 is removed from the region of the gasifier container 47 beneath the grate 53 through a product gas vent 65. The product gas 11 is then cooled in the heat exchanger system 28 in accordance with
Both the tubular gasifier container 47 and the tubular gasifier component 50 have a circular cross-section and are arranged concentrically to one another. The tubular gasifier component 50 has an outer diameter 67 that is smaller than the inner diameter 68 of the tubular gasifier container 47.
Although the present invention has been described in connection with certain specific embodiments for instructional purposes, the present invention is not limited thereto. Accordingly, various modifications, adaptations, and combinations of various features of the described embodiments can be practiced without departing from the scope of the invention as set forth in the claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102015210826.0 | Jun 2015 | DE | national |
| PCT/EP2016/063507 | Jun 2016 | EP | regional |
This application is filed under 35 U.S.C. § 111(a) and is based on and hereby claims priority under 35 U.S.C. § 120 and § 365(c) from International Application No. PCT/EP2016/063507, filed on Jun. 13, 2016, and published as WO 2016/198693 A1 on Dec. 15, 2016, which in turn claims priority from German Application No. 102015210826.0, filed in Germany on Jun. 12, 2015. This application is a continuation-in-part of International Application No. PCT/EP2016/063507, which is a continuation of German Application No. 102015210826.0. International Application No. PCT/EP2016/063507 is pending as of the filing date of this application, and the United States is an elected state in International Application No. PCT/EP2016/063507. This application claims the benefit under 35 U.S.C. § 119 from German Application No. 102015210826.0. The disclosure of each of the foregoing documents is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/EP2016/063507 | Jun 2016 | US |
| Child | 15836844 | US |
