DE102011107685A1 - Method and apparatus for recovering heat energy from coils - Google Patents

Abstract

In a method for recovering heat energy from one or more superheated coil (s) (30), in which the coil (30) is transported along a heat absorber device from at least one heat absorber (8) during its transport from its production site, the coil (30) transferred heat energy substantially to a liquid (F), such as water, water vapor or an oil, in a heat absorber (8). Furthermore, in a device (1) for recovering heat energy after the production of a coil along a transport path (31) of the heated coil (30) from its production site and at least on one side of the transport path (31), a heat absorber device comprising at least one heat absorber (8 ), wherein the heat absorber (8) is designed to flow through suitable for receiving heat energy liquid (F) and the heat absorber or heat absorber (8) with supply and discharge lines (12, 9) for the heat energy absorbing liquid (F) provided are.

Description

The invention relates to a method for recovering heat energy from a highly heated coil during transport of the coil from its production site along a heat absorber device comprising at least one heat absorber. It further relates to a device for recovering heat energy after the production of a metal strip or wire coil.

The coil (strip steel roll or steel wire roll) is the common form for the provision and transport of wide-area products of metals and metal alloys for further processing. For the production of steel strip (steel wire), metal blocks are heated and rolled. After rolling, the strip-shaped, superheated metal is wound into a coil. For decades, such a coil, which weighs up to 40 tons, has been cooled in the air after its manufacture. The thermal energy of these coils is lost unused.

The WO 2010/113410 A1 proposes a method for recovering the thermal energy of a coil just produced, in which it is flowed around with a gaseous medium which is to absorb the heat energy. The thereby heated gaseous medium is compressed in the following; the carried heat energy can be made available to another process.

A disadvantage of the known method is the transfer of heat energy to a gaseous medium, because a further process step, namely the compression of the gaseous medium is necessary and the compressed gaseous medium can not easily be transported over long distances to use at another location Find.

The invention is therefore based on the object to provide an improved method for recovering the heat energy from coils heated by the production without the disadvantages of the known method.

The invention thus relates to a process for the recovery of heat energy from one (or more) heated coil (s), in which the coil is guided during transport from its production site along a heat absorber from at least one heat absorber, wherein the heat energy emitted by the coil essentially to a liquid in a heat absorber and the liquid is water, water vapor or an oil.

The invention further relates to a device for recovering heat energy after the production of a coil in which along a transport path of the heated coil from its production site and at least on one side of the transport path a heat absorber is arranged from at least one heat absorber, the heat absorber can be flowed through for a Absorption of heat energy suitable liquid is formed and the heat absorber or heat absorber are provided with inlets and outlets for the heat energy absorbing liquid.

The advantage of the method according to the invention is that the transferred to a liquid medium can be easily transported over long distances for further use. Liquids allow a simpler and cheaper design of pumps and pipes for transport. Liquids no longer need to be compressed, as is required with gaseous media.

To transfer the heat from the coil to the liquid heat absorber are used, which are flowed through by the liquid. Direct contact between liquid and coil is not necessary. The heat energy is released from the highly heated coils by thermal radiation and carried by the liquid.

1 schematically shows a side view of a device according to the invention.

2 schematically shows cross sections of the possible different sections of the device according to the invention 1 ,

3 schematically shows a cross section of the heat absorber portion of the device according to the invention.

4 schematically shows a cross section of a portion of the device according to the invention, in which the heat transfer from the coil to a gaseous medium takes place mainly by convection.

5 shows the temperature profile of the cooling of a coil under different experimental conditions.

The individual sections of the method according to the invention can be accommodated in one or more housings. According to one embodiment of the invention, each section of the method may be arranged in a single enclosure.

The temperature of the coils during transport from their production facility, for example a rolling mill, ie at the beginning of the process according to the invention, should be above 350.degree. It can be at 400 ° C to 900 ° C, especially at 600 ° C to 700 ° C.

The heat absorbers used according to the invention are hollow bodies and can be flowed through for a liquid. They have a liquid delivery and laxative. The heat absorbers may be formed as plates or tubes. Heat absorbers of this type are known and available on the market, for example, as so-called radiant panels or dark spotlights.

A heat absorber in the form of a continuous plate has the advantage of a larger area for heat absorption than a plurality of spaced tubes. The area of tubular heat absorbers can be increased by arranging further tubes behind the interstices of the tubes. As a result, a larger area is achieved overall than in the plate-shaped heat absorbers. However, such an arrangement is structurally complex.

The heat absorber may comprise a plurality of heat absorbers. The heat absorber and heat absorber may be a structural element of an enclosure surrounding the transport path of the coil from its production site.

Heat absorbers may preferably be arranged on both sides along the transport path of the coil for receiving heat energy from the coil. Heat absorbers may preferably be arranged to receive heat energy from the coil also above the transport path of the coil from its production site.

The liquid flowing through the heat absorber can be conducted in countercurrent to the transport direction of the coils or in cocurrent to the transport direction.

The flow direction of the liquid through a heat absorber can be opposite to the movement of the coils. This has the advantage that the coils cooling down in the course of the transport meet ever colder heat absorbers and thus counteract the decrease in the net heat flow.

The heat absorber may be part of a circulatory system comprising a liquid feed and a liquid recirculation, wherein the liquid heated in the heat absorber is supplied to the flow of the circulating system and the liquid to be heated in the heat absorber is removed from the return of the circulatory system and wherein the heat energy from the feed is a heat energy consumer supplied and / or carried. The heat absorber can also have its own fluid circuit, which is connected via control valves to the circulation system.

In the previously described embodiment of the method according to the invention, the release of heat through the coil takes place as far as possible by thermal radiation. According to a preferred embodiment of the method according to the invention can be applied in a further process section, the coil with a gaseous medium, preferably air, substantially in transverse flow to the direction of movement of the coil, so that emitted by the coil heat energy is transferred by convection to the gaseous medium.

For this purpose, a further housing may be provided which has gas supply means and at least one discharge device for the convection heated by gaseous medium, and means for gas delivery, which are arranged so that the gaseous medium G at least partially in a direction of movement of the coils substantially in the cross flow through the enclosure is eligible. In this case, the means for conveying the gas are preferably arranged so that the gaseous medium flows from one section within the housing to the next section in opposite directions in the transverse flow for the movement of the coils.

The heat energy transferred to a gas by convection in this preferably additionally present process section can be transferred to another medium, in particular a liquid, for example in a heat exchanger. This heat exchanger can be connected directly to the return and flow of the liquid circulation system. However, the heat exchanger may also have its own pump circuit operated by liquid, which are connected via control valves to the liquid circulation system.

When using an industrial water as a heat transfer fluid, which is to absorb the heat energy, the heat transfer fluid at entry into a first heat absorber at the beginning of the inventive method, a temperature of 50 to 150 ° C, preferably in the range of 80 to 130 ° C, exhibit. The temperature of heat transfer fluid is particularly preferably 90 to 120 ° C.

The temperature of the liquid to be heated can be controlled by regulating the flow rate, the volume of heat absorbers flowing through, and the type of liquid.

The temperature of the heat transfer fluid leaving the last heat absorber in a section where the heat energy of the coil is largely released by heat radiation may be in the range of 100 to 170 ° C.

Up to a temperature of the heat transfer fluid of 170 ° C, the associated pressures in the piping systems still allow an economic design of the fluid circuit. However, as the temperature of the heat transfer fluid increases, the temperature difference (delta T) to the coil decreases, which reduces the energy transfer efficiency.

Therefore, a temperature of the heat transfer fluid when leaving the last heat absorber of 120 ° C to 150 ° C is preferred. Suitable heat absorbers for this purpose are known and available on the market.

The maximum temperature of the heat transfer fluid in the heat absorber will depend on the robustness of the heat absorber and thus on its design.

According to a further preferred embodiment of the method according to the invention, the heated liquid can be supplied to a liquid supply of a circulatory system and the liquid to be heated in a heat absorber taken from a liquid return of the circulatory system and the heat transferred from the liquid flow to another medium.

The pressure in the heat absorber can be in the range of 100,000 to 800,000 Pa. The pressure in the pipe system depends on the temperature of the liquid and the flow velocity. Liquid pressures of up to 800,000 Pa, for example, allow economically viable design of the pipe systems and pumps. Due to the flow rates and temperatures to be chosen, a minimum pressure value may be 100,000 Pa.

Due to the temperature reduction of the coil after the first stage of the process and to increase the yield of heat energy from the coils, it is advantageous to carry out a heat transfer to a gaseous medium by convection in a second process stage. Preferably, the gaseous medium is blown through the enclosure, for example, by a fan in order to absorb the heat of the coils as comprehensively as possible. The heated air can then be removed by a derivative of the housing and fed to a heat exchanger. This heat exchanger liquid can be supplied from the liquid return and heated by the heated, gaseous medium to the temperature of the liquid flow. The liquid thus heated in the heat exchanger can be supplied to the flow of the liquid circulation system. The second stage of the process may be followed by further stages of the process.

The device according to the invention can have an enclosure. The enclosure may be formed by the heat absorber. However, an enclosure can also have a plurality of inner surfaces, spaced apart from the coils liquid-flow heat absorber. The distance of a heat absorber to the coil is chosen so that the coils are not on the one hand in direct contact with the heat absorber and on the other hand still so close that a high heat transfer is ensured. The distance between coil and heat exchanger may preferably be 50 to 500 mm, preferably the distance may be between 100 and 300 mm.

The heat absorbers should cover as much of the inner surface of the enclosure as possible. The heat absorbers may either be directly coupled to one another or connected to the fluid flow and return of a circulatory system. It is preferable to arrange individual heat absorbers directly coupled to one another in the transport direction of the coils on the inner surfaces of the housing, so that a group of heat absorbers on an inner surface of the housing has in each case a liquid feed and a liquid discharge.

In a further preferred embodiment of the device according to the invention, the heat absorber has a rough surface. Rough surfaces have the advantage over smooth surfaces that the specific heat coefficient of rough surfaces is higher and thus a larger amount of heat energy per surface can be accommodated.

In a further preferred embodiment of the device according to the invention, the heat absorber has a dark surface. It is preferably a black surface. The specific heat absorption coefficient of a surface increases the darker the surface is, the maximum value is achieved with a black surface.

The liquid in the liquid circulation system, ie the liquid flow and the Liquid return can be moved by one or more pumps.

Heat absorbers can either be supplied with water by the pumps of the liquid circulation system or can have a separate liquid circuit with their own pump. Further, the connection between the flow and heat absorber and the connection between the return and heat absorber may be connected via a three-way valve. Such a direct connection via a three-way valve has the advantage that the liquid to be heated from the return, it should be too warm, be introduced directly into flow via this three-way valve. According to a further preferred embodiment of the device according to the invention, the housing includes a transport device for coils with which the at least one coil is movable.

An exemplary embodiment of the invention will be explained below with reference to the figures.

The energy recovery device 1 in 1 includes a first enclosure 3 , a second enclosure 2 and a third enclosure 4 , In the first enclosure 2 are on the upper inner surface 7 liquid-flow, plate-shaped heat absorber 8th are arranged. The individual heat absorbers 8th are directly connected to each other, leaving the fluid F from a heat absorber 8th can flow to the next. The group of heat absorbers 8th on the upper inner surface 7 have a liquid feed 9 , This 9 is with the water return 10 a water circulation system 11 connected. Furthermore, the group points to heat absorbers 8th a liquid drain 8th on. This liquid drain 12 is with the water supply 13 the water circulation system 11 connected.

The second enclosure 3 indicates at the front end 5 a first air discharge device 15 with a first fan 16 on. The first air discharge device 15 is with a first heat exchanger 17 connected such that the air G the first heat exchanger 17 can be supplied. The first heat exchanger 17 is via piping both with the water return 10 as well as with the water supply 13 connected. At the far end 18 the second enclosure 3 there is a gas introduction device 19 with a first blower 20 , Inside the second enclosure 2 are on the side walls alternately cross-flow fan 20 arranged.

Accordingly, on the side inner surfaces of the third enclosure 4 alternately on the opposite sides crossflow fan 20 arranged. The third enclosure 4 points near the front end 21 a second air discharge device 22 with a second fan 23 on. Through the second air discharge device 22 air is transferred to a second heat exchanger 24 guided, in turn, via a pipe system with the air introduction device 15 the second enclosure 3 connected is. The second heat exchanger 24 is also with the water return 10 and the water supply 13 the water circulation system 11 connected via a pipeline. At the far end 25 the third enclosure 4 there is an air introduction device 27 with a blower and a fresh air filter 28 ,

In the floor area below the enclosures 2 . 3 and 4 there is a transport device 29 for the coils, with which the coils 30 through the enclosures 2 . 3 and 4 be transported.

2 shows in cross section the three enclosures 2 . 3 and 4 the energy recovery device 1 of the 1 , Contrary to the actual arrangement of the enclosures 2 . 3 . 4 one behind the other are the cross sections of the enclosures 2 . 3 . 4 shown side by side. In 2 is also the liquid circulation system 11 represented as well as the compounds of the liquid flow 13 and the water return 10 to the first heat exchanger 17 and the second heat exchanger 24 as well as to the three groups of heat absorbers 8th in the first enclosure 2 ,

In the cross section of the first enclosure 2 are next to the group of heat exchangers 8th on the upper inner surface 7 also the heat absorbers 8th shown on the lateral inner surfaces. Each of the three groups has its own fluid supply 9 and its own liquid drainage 12 , In the middle of the three enclosure cross sections 2 . 3 and 4 there is one coil each 30 ,

An exemplary embodiment of the method according to the invention will be described below with reference to FIGS 1 and 2 described.

The hot coils 30 with a temperature of about 650 ° C are on a transport device 29 through the first enclosure 2 emotional. This heat energy of the coils 30 by heat radiation on the plate-shaped heat absorber 8th . 32 . 33 and transferred from there to the heat absorber passing liquid.

The coils 30 leave the first enclosure 2 with a temperature of about 500 ° C and enter the second enclosure 3 one. When transported through the second enclosure, the coils are flowed around by the air G and thereby transfer the heat energy to the air G. At the exit from the second enclosure 3 the coils have a temperature of about 450 ° C. In the third enclosure 4 become the coils were finally cooled by air circulation to a temperature of 400 ° C.

The path of the air G through the energy recovery device 1 begins with the intake of fresh air G by means of a blower 27 from the gas introduction device 26 the third enclosure 4 , The air is through the fresh air filter 28 filtered. The air is in cross flow to the coils 30 from a side wall of the third enclosure 4 moved to the other side wall and then moved along the side wall and against the movement of the coils on. Thereupon, air from a fan arranged on the second side wall is again directed in the direction of the first side wall in transverse flow to the coils 30 emotional.

At the same time air G heats up from entrance to the third enclosure 4 until the exit from 20 ° C to 240 ° C. In the second heat exchanger 24 The air is then cooled to a temperature of 180 ° C and introduced into the second enclosure. The airway within the second enclosure 3 is according to the inside of the third enclosure 4 , At the exit from the second enclosure 3 the air has a temperature of 320 ° C and is passed through the first heat exchanger and then discharged to the environment. The two heat exchangers 17 and 24 are each connected to the liquid flow and return of the liquid circulation system and thus transmit those of the coils 30 transferred to the air G heat energy to the liquid circulation system.

The temperature in the water supply 13 is about 130 ° C, that of the water return 10 about 110 ° C. The water F of the water return 10 becomes the heat absorber 8th , as well as the heat exchangers 17 and 24 fed, heated therein and then in the water supply 13 initiated.

3 is a section of the energy recovery device described above 1 , The detail shows only a cross section of the first enclosure 2 with the heat absorbers arranged on the inner surfaces of the enclosure 8th . 32 . 33 , Exemplary is only at the arranged on the left side wall heat absorber 32 the connection to the fluid circuit system 11 shown. In 3 It is emphasized that the heat absorber has its own fluid circuit with pump 34 and three-way valve 35 can dispose of. With the help of this arrangement can be adjusted to temperature fluctuations in the liquid circulation system 11 be reacted and too hot liquid from the liquid reflux 10 directly to the liquid flow 13 be fed again.

The injection of air to receive the heat energy of the coils by convection is in 4 shown. After flowing around the coils 30 the air G is in the heat exchanger 24 sucked and gives heat to the liquid of the liquid reflux 14 from.

5 shows a heat diagram for the cooling of a coil as a function of time at four different experimental conditions. The temperature profile is shown for a total duration of 120 minutes and the initial temperature is 550 ° C.

In the first experimental approach, the coils were left outdoors in the air. The solid line shows the temperature profile of this approach.

In the second experimental approach "cooling radiation 33% + air 67% Alfa 25", the coil was cooled in an energy recovery device according to the invention. In the first third, that is, in the first 40 minutes, the cooling took place in the presence of cooled radiant panels, which absorb the heat radiation of the coil. In the last two-thirds, ie from minute 41 to 120, was surrounded by cool air. The temperature profile of this approach is shown as a dashed line. In the first 40 minutes, the temperature is the same as in outdoor cooling, the air circulation increases the cooling rate and the coil reaches a final temperature of about 420 ° C.

The third experimental approach "cooling radiation 33% + air 67% Alfa 100" differs from the second by a higher speed of air. This achieves an even higher cooling rate in the second third. The temperature profile of this approach is shown as a dashed line. The final temperature is around 370 ° C.

In the fourth approach, "Cooling air 100% Alfa 50", the coil is surrounded by air over the entire duration. The flow rate of the air is between the flow rates of the lugs 2 and 3. The temperature profile of this approach is shown as a dashed line. The final temperature is around 380 ° C.

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• WO 2010/113410 A1 [0003]

Claims (14)

Method for recovering heat energy from one or more superheated coil (s) ( 30 ) in which the coil ( 30 ) is guided during transport from its production site along a heat absorber from at least one heat absorber, characterized in that the one of the coil ( 30 ) heat energy substantially to a liquid (F) in a heat absorber ( 8th ) and the fluid (F) is water, water vapor or an oil. A method according to claim 1, characterized in that the temperature of the coil is at least 200 ° C above the ambient temperature. Method according to claim 1 or 2, characterized in that the heat absorber ( 8th ) is formed substantially plate-shaped. Method according to one of claims 1 to 3, characterized in that Wäremeabsorber construction element of a transport path of the coil ( 30 ) housing surrounding its production site ( 2 ) are. A method according to claim 4, characterized in that heat absorber on both sides along the transport path of the coil ( 30 ) for receiving heat energy from the coil (3 = are arranged. A method according to claim 4 or 5, characterized in that above the transport path heat absorber ( 8th ) for absorbing heat energy from the coil ( 30 ) are arranged. Method according to one of claims 1 to 6, characterized in that the heat absorber device part of a circulatory system ( 11 ) is, of a liquid flow ( 13 ) and a liquid return ( 9 ), wherein the heated in the heat absorber liquid (F) the flow ( 13 ) of the circulatory system ( 11 ) and to be heated in the heat absorber liquid (F) the return ( 9 ) of the circulatory system ( 11 ) and wherein the heat energy from the flow ( 9 ) is supplied or carried to a heat energy consumer. Method according to claim 1, characterized in that, in a further process stage, the coil is subjected to a gaseous medium (G) substantially in cross-flow with respect to the direction of movement of the coil, so that the coils of the coil ( 30 ) is at least partially transferred to the gaseous medium (G). A method according to claim 8, characterized in that the absorbed heat energy from the gaseous medium (G) by means of heat exchangers ( 17 ) is transferred to another medium, in particular a liquid. Device for recovering heat energy after the production of a coil ( 30 ), characterized in that along a transport path ( 31 ) of the heated coil from its production site and at least on one side of the transport route ( 31 ) a heat absorber device comprising at least one heat absorber ( 8th ), the heat absorber ( 8th ) is designed for a suitable for receiving heat energy liquid (F) and the heat absorber or heat absorber with supply and discharge lines ( 12 . 9 ) are provided for the heat energy absorbing liquid (F). Device according to claim 10, characterized in that the heat absorbers ( 8th ) is formed from plate-shaped or tubular hollow bodies. Device according to claim 10 or 11, characterized in that heat absorbers ( 8th ) Construction element of a transport path of the coil ( 30 ) are enclosing its production site housing. Device according to one of claims 10 to 12, characterized in that heat absorber ( 8th ) on both sides along the transport path of the coil ( 30 ) for absorbing heat energy from the coil ( 30 ) are arranged. Device according to one of claims 10 to 13, characterized in that it comprises a further section in which means for applying coils ( 30 ) are arranged with a gaseous medium (G) substantially in cross-flow to the direction of movement of the coil, so that by a coil ( 30 ) is at least partially transferred to the gaseous medium (G).

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