DE102010041231A1 - Method and device for heat recovery method for a dryer section of a machine for producing a fibrous web - Google Patents

Abstract

The invention relates to a method for heat recovery for a dryer section of a machine for producing a fibrous web (F), in particular a paper, cardboard or tissue web, the fibrous web (F) having at least one steam-heated drying cylinder (1) and at least one high-temperature hood ( L1) is dried with hot air, the at least one drying cylinder (1) being at least partially charged with live steam (D1), the condensate / steam mixture (K1) of the at least one drying cylinder (1) being fed to a condensate separator (A1), wherein the steam (D3) from the condensate separator (A1) is fed to the live steam (D1) or a live steam / high-pressure steam mixture (D1,2), at least part of the condensate (K3) from the condensate separator connected downstream of the at least one drying cylinder (1) (A1) is fed to a heat exchanger (W1) in the exhaust air flow (L6) of the high-temperature hood (L1), and the condensate (K3,4) is heated there absorbs rd and energy of the exhaust air (L6), is then expanded by a pressure-reducing element (DR1) and thereby at least partially evaporated again. The method according to the invention is characterized in that the condensate (K * 3,4) heated by the heat exchanger (W1), which was subsequently expanded by a pressure-reducing element (DR1) and thereby at least partially evaporated again, at least partially as high-pressure steam (D2 ) is fed into a steam line or a steam container, the pressure of which is higher than the pressure of the condensate separator (A1) connected downstream of the at least one drying cylinder (1). The application also relates to a device (100) for carrying out the method according to the invention.

Description

The invention relates to a method for heat recovery for a dryer section of a machine for producing a fibrous web, in particular a paper, board or tissue web, wherein the fibrous web is dried at least with a steam-heated drying cylinder and at least one high-temperature hood with hot air, wherein the at least one drying cylinder at least partially applied with live steam, wherein the condensate / steam mixture of the at least one drying cylinder is fed to a condensate, wherein the steam from the Kondensatabscheider the live steam or a live steam / high pressure steam mixture is supplied, wherein at least a portion of the condensate from the at least one Drying cylinder downstream condensate is fed to a heat exchanger in the exhaust air stream of the high-temperature hood, and wherein the condensate is heated there and absorbs energy of the exhaust air, then ents ents by a pressure-reducing element is panned and thereby at least partially evaporated again.

Furthermore, the invention relates to a device for heat recovery for a dryer section of a machine for producing a fibrous web, in particular a paper, board or tissue web, in which a fibrous web is dried, consisting of at least one steam-heated drying cylinder and at least one high-temperature hood which acts with hot air wherein the at least one drying cylinder is at least partially supplied with live steam, wherein the condensate / steam mixture of the at least one drying cylinder is fed to a condensate, wherein the steam from the Kondensatabscheider the live steam or a live steam / high pressure steam mixture is supplied, wherein at least a portion the condensate from the at least one drying cylinder downstream condensate is fed to a heat exchanger in the exhaust air stream of the high-temperature hood, and wherein the condensate is heated there and absorbs energy of the exhaust air, in the connection s is relaxed by a pressure-reducing element and thereby at least partially evaporated again.

Such a method, or such a device is for example from the document AT 506 077 B1 known. A method and apparatus for heat recovery in a dryer section of a paper machine is disclosed wherein a paper web is dried with a steam heated drying cylinder and a hot air supplied high temperature hood and exhaust steam is fed from a steam system to a vapor separator, wherein a portion of the condensate from the vapor separator in a a separate circuit is recycled via a heat exchanger back into the same and single steam separator and the condensate is supplied via the heat exchanger heat from the exhaust air of the high-temperature hood. The invention had the object of providing an improved and easier controllable heat recovery process available. The improvement seen by the applicant there compared to the prior art is that the heating of the condensate in the heat exchanger mentioned does not have to result completely in evaporation, since the steam, or else the vapor / condensate mixture, is returned to the said condensate separator. An elaborate control of the condensate flow through the heat exchanger to account for the evaporation capacity of the heat exchanger, which in turn depends on an optionally fluctuating exhaust air temperature, omitted.

Furthermore, from the document DE 35 01 584 A1 a device on a drying section of paper machines known, which consists of drying cylinders and at least one high-temperature hood. The invention in this application was based on the object to use the energy content of the exhaust air and thereby reduce the primary energy use for drying. Furthermore, the inventive solution should be retrofittable to existing systems. According to the invention, this object is achieved in that the cylinder in a conventional manner, a vapor separator for separating the exhaust steam is connected, on the one hand, the vapor separator is connected to a Schlupfdampfleitung and a compressor to the feed line to the drying cylinder, and on the other hand, the condensate line of the vapor separator is connected via the heat exchanger of the high temperature hood with the Schlupfdampfleitung.

Note: In the literature, different names are used alternately for the same procedural device: steam separator or condensate separator or separator. In the context of this writing, all three names have the same meaning. However, it has been tried in the following to consistently use the name Kondensatabscheider.

The present invention has for its object to improve a method and an apparatus of the aforementioned types for heat recovery in such a way over the prior art that the offered energy of the exhaust air flow of at least one high-temperature hood is used thermodynamically at the highest possible level.

This object is achieved in the method according to the invention that by the condensate heated by the heat exchanger, which is subsequently expanded by a pressure-reducing element and thereby at least partially evaporated again, is at least partially fed as high-pressure steam into a steam line or vapor vessel whose pressure is higher than the pressure of the condensate separator connected downstream of the at least one drying cylinder.

Live steam is understood in this application as steam, whose production does not emerge from this description or from the figures. The production of live steam could take place in a boiler house or in another steam generator. Another steam generator could also be a steam generator that uses the burner capacity of a hot air hood.

The thermodynamic advantage is that the condensate can be heated to a very high temperature in the heat exchanger, resulting in a very high vapor pressure after recuperation. Because the resulting steam is fed into a steam line or vapor vessel, the pressure of which is higher than the pressure of the condensate downstream of the at least one drying cylinder, there is no system-limited limit on the pressure of the resulting vapor, as is the case, for example would feed the steam in a condensate, which is immediately downstream of a drying cylinder and therefore there must prevail the condensate side pressure of the drying cylinder.

Another advantage is that the entire heat recovery system without compressor, which are located in a steam-containing line, gets along.

It is advantageous that the condensate re-evaporated by the pressure-reducing element is fed to a second condensate separator, since this ensures that condensate possibly contained in the steam can be safely separated.

Advantageously, the steam line or the steam tank into which the high-pressure steam is fed, be the line is guided in the live steam.

Alternatively, or else additional, the steam line or the steam tank, in which the high-pressure steam is fed, be the line in which the steam mixture of live steam and steam from the at least one drying cylinder downstream condensate is performed.

The resulting condensate, which can form in the second condensate, is advantageously, at least partially, again supplied to the heat exchanger. There, the condensate that comes from the second condensate can be reheated and thus can form a higher temperature of the condensate, which in turn can lead to a higher pressure on the second Kondensatabscheider, or to a higher pressure possible high pressure steam.

The resulting condensate, which may form in the second condensate separator, may alternatively be supplied via a pressure-reducing element to at least a portion, preferably for the most part, the condensate separator to which the condensate / vapor mixture of the at least one drying cylinder is also fed, so that the condensate of the second condensate can evaporate via this pressure-reducing element.

The resulting condensate, which may form in the second condensate separator, may alternatively be supplied at least in part, preferably for the most part, to a third condensate separator via a pressure-reducing element, which may be a diaphragm or, preferably, a valve.

The resulting vapor of this third condensate separator can be used in at least two variants:
On the one hand, this steam can be fed into the line in which the steam mixture of live steam and steam is passed out of the at least one drying cylinder downstream condensate. This variant has the thermodynamic advantage that the heated by the heat exchanger condensate can evaporate in two stages, each of which is higher than the pressure of the at least one drying cylinder downstream condensate. In other words, the heated condensate from the heat exchanger can be fed via the second Kondensatabscheider as high pressure steam in the live steam, and the still hot condensate from the third Kondensatabscheider can be fed as steam in the line in which the steam mixture of live steam and steam out of the at least one drying cylinder downstream condensate.

On the other hand, the vapor of the third condensate can be combined with the steam of the at least one drying cylinder downstream condensate. In this variant, the third condensate and the at least one Drying cylinder downstream condensate be interconnected communicating. Communicating means in this context without closed shut-off devices; It is possible that prevail in both condensate equal pressure conditions. This variant is particularly suitable for conversions of the heat recovery system, since the capacity of an existing condensate, which is connected downstream of the at least one drying cylinder, can continue to be used. The third condensate separator fulfills the function described above and, in effect, extends the capacity of the existing condensate separator.

If a valve is used as the pressure-reducing element after the heat exchanger for the expansion of the condensate, there is the advantage that the pressure downstream of the pressure-reducing element, and thus the pressure at the second condensate separator, can be influenced.

If a valve is used as a pressure-reducing element after the heat exchanger for the expansion of the condensate, this can be advantageously controlled according to a pressure setpoint, the pressure actual value of which represents the pressure at the second condensate separator. The pressure can be ideally measured at the second condensate separator, since this belongs to the so-called controlled system of the valve.

This pressure setpoint can now be generated automatically in a further embodiment according to the Druckist- / or pressure setpoint in the steam line or the steam tank, the pressure of which is higher than the pressure of the at least one drying cylinder downstream condensate.

Finally, as the desired pressure value, a value can be generated which is greater than the pressure setpoint or pressure setpoint in the steam line or the steam container, the pressure of which is higher than the pressure of the condensate separator downstream of the at least one drying cylinder. It is thus achieved that in a eingependelten operating state of the generated high-pressure steam can flow safely.

If a valve is used as a pressure-reducing element after the heat exchanger for the expansion of the condensate, so can be controlled alternatively to the aforementioned control versions to a pressure setpoint whose actual pressure is the condensate pressure on or after the heat exchanger. After the heat exchanger is called here between the heat exchanger and said pressure-reducing valve. This alternative control would have the advantage that the pressure of the condensate in the heat exchanger can be kept so high explicitly via the pressure-reducing valve that unwanted evaporation of the condensate at the heat exchanger is prevented.

It is also advantageous that unwanted return flow of steam of the steam line or the steam tank, the pressure of which is higher than the pressure of the at least one drying cylinder downstream condensate to prevent mechanically into the high-pressure steam. A non-return valve, preferably a check valve, could prevent the undesirable backflow.

Since the best possible heat transfer in the heat exchanger is desired, it should be advantageously ensured that the condensate does not evaporate in the heat exchanger. Vaporizing already in the heat exchanger would be an unwanted operating condition and, moreover, would considerably impair the heat transfer in the heat exchanger. Advantageously, the pressure of the condensate is raised to a sufficient pressure level, so that it is ensured that the condensate does not evaporate unintentionally. To increase the pressure in this area, a pump upstream of the heat exchanger can be used.

The generation of hot condensate via the heat exchanger is largely determined by the energy offered in the exhaust air stream of the high-temperature hood. Operating conditions, in particular safety-relevant requirements, can lead to bypassing, or at least partially bypassing, the exhaust air of the high-temperature hood around the heat exchanger. For example, an exhaust bypass system can prevent unwanted, excessive heating of the condensate by passing the exhaust air from the high-temperature hood through a bypass on the heat exchanger.

The object of the invention is achieved in a device of the type mentioned in that the heated by the heat exchanger condensate, which was subsequently relaxed by a pressure-reducing element and thereby at least partially evaporated again, via at least one line as high-pressure steam to a steam line or a steam tank is connected, the pressure is higher than the pressure of the at least one drying cylinder downstream condensate.

The thermodynamic advantages of the device arise in accordance with the thermodynamic advantages of the method according to the invention.

Just as advantageous as in the described method, dispenses with the invention Device on compressors, which are located in steam pipes. This is advantageous from an investment as well as from an operating cost point of view.

The pressure-reducing element is advantageously followed by a second Kondensatabscheider. This condensate separator allows non-evaporated condensate to collect there specifically.

Advantageously, the steam line or the steam tank into which the high-pressure steam is fed, be the line is guided in the live steam.

Alternatively, or else additional, the steam line or the steam tank, in which the high-pressure steam is fed, be the line in which the steam mixture of live steam and steam from the at least one drying cylinder downstream condensate is performed.

Advantageously, the conduit which carries the condensate from the second condensate separator is connected to the conduit to the heat exchanger. This thermodynamically has the advantage that the already heated condensate from the second condensate can be driven again over the heat exchanger. In continuous operation of the system can thus set a desired pressure level in the second condensate.

Alternatively, the conduit which carries the condensate from the second condensate separator may be connected to the condensate separator, which is also supplied with the condensate / vapor mixture of the at least one drying cylinder, wherein a pressure-reducing element, preferably a valve or orifice, is located in this conduit , Advantage of this arrangement is that the condensate from the second condensate directly back into the Kondensatabscheider, which is also fed to the condensate / vapor mixture of at least one drying cylinder, can evaporate.

Alternatively, the conduit which carries the condensate from the second condensate separator may be connected to a third condensate separator. In this line, a pressure-reducing element, preferably a valve or a diaphragm may be located.

The line that carries steam from this third condensate separator can be connected to various other lines.

On the one hand, the line leading from this third condensate vapor can be connected to the line in which the vapor mixture of live steam and steam from the at least one drying cylinder downstream condensate is performed. This variant has the thermodynamic advantage that the heated by the heat exchanger condensate can evaporate in two stages, each of which is higher than the pressure of the at least one drying cylinder downstream condensate. In other words, the heated condensate from the heat exchanger can be fed via the second Kondensatabscheider as high pressure steam in the live steam, and the still hot condensate from the third Kondensatabscheider can be fed as steam in the line in which the steam mixture of live steam and steam out of the at least one drying cylinder downstream condensate.

On the other hand, the line leading from this third condensate steam, connected to the line, which leads the steam from the at least one drying cylinder downstream Kondensatabscheider. This variant is particularly suitable for conversions of the heat recovery system, since the capacity of an existing condensate, which is connected downstream of the at least one drying cylinder, can continue to be used.

The pressure-reducing element is advantageously designed as a valve. A valve has the advantage that the pressure gradient can be adjusted specifically at this point. An orifice whose geometric flow area is designed according to the operating conditions and the desired pressure gradient can be used as a pressure-reducing element as an alternative to a valve.

To a safer inflow of high-pressure steam into the steam line or a steam tank, the pressure of which is higher than the pressure of the at least one drying cylinder 1 downstream condensate separator A1, is a mechanical non-return element, preferably a mechanical check valve, an advantage. Only if the high pressure steam is greater than z. B. has the live steam, high pressure steam should flow into the line of live steam. If the high-pressure steam is lower in pressure than the live steam, it is intended to prevent fresh steam from flowing into the high-pressure steam through the mechanical non-return element. However, it is also a controlled valve that takes over the function of the check valve, conceivable in this position. This would even have the advantage that when starting the entire device, a targeted, partial filling of the second condensate could be done with steam.

The heat exchanger is advantageously preceded by a pump which is able to produce a pressure of condensate to the heat exchanger, which is higher than the temperature corresponding evaporation pressure of the condensate in the heat exchanger. The pressure of the condensate can be explicitly set via the pump in such a way that no unwanted vaporization occurs at a given temperature of the condensate.

Hereinafter, advantageous embodiments of the invention will be explained with reference to embodiments and with reference to the figures.

Show it:

1 A schematic representation of a preferred embodiment of the invention.

2 Another schematic representation of a preferred embodiment of the invention.

3 Another schematic representation of a preferred embodiment of the invention.

4 Another schematic representation of a preferred embodiment of the invention.

5 Another schematic representation of a preferred embodiment of the invention.

6 Another schematic representation of a preferred embodiment of the invention.

7 Another schematic representation of a preferred embodiment of the invention.

8th Another schematic representation of a preferred embodiment of the invention.

The 1 shows a preferred embodiment of the invention in which a fibrous web F is dried. The fibrous web F is a drying cylinder 1 , which is acted upon by steam, guided. It can also be seen a high-temperature hood L1, which acts on the fibrous web F with hot air.

The air system of the high-temperature hood L1 has a circulation fan L3 with a subsequent gas burner L2 for heating the circulating air L4 performed. It is a large part of the circulating air L4, which is guided by the high-temperature hood L1, circulated directly in this recirculation system. Since the circulating air L4 can absorb only a finite degree of water, circulating circulating air L4 is partially removed via the exhaust air system and replaced by supply air L7. The exhaust air system consists of an exhaust fan L5 and several heat exchangers W1 and L8. Heat exchangers L8 may be a plurality of heat exchangers for warming up process water or for heating air, such as supply air L7 for high temperature hood L1. Since the heat exchangers L8 are not obvious from this invention, the use is not discussed in more detail. However, in the exhaust air flow is a heat exchanger W1, whose function is related to the invention. In this heat exchanger W1 condensate is heated from a steam and condensate system. The exhaust air L6 can be passed to the heat exchanger W1 wholly or partially by an exhaust air bypass system. Of course, the exhaust air bypass system can be switched so that the whole exhaust air L6 is passed through the heat exchanger W1.

The steam and condensate system feeds the drying cylinder 1 with steam, wherein the steam may be a mixture of different steam pressure stages and steam from different heat recovery stages. The steam D1,2,3, the drying cylinder 1 is fed, condenses due to the heat transfer through the drying cylinder 1 to the fibrous web F and is called condensate / vapor mixture K1 from the drying cylinder 1 dissipated. The condensate / vapor mixture K1 from the drying cylinder 1 is fed to a first condensate separator A1. In this first condensate separator A1 contained steam from the condensate / vapor mixture K1 from the drying cylinder 1 ascend as separated steam. In addition, condensate can re-evaporate due to the pressure conditions in the first condensate A1 and rises as so-called Brüdendampf. The separated steam and the so-called Brüdendampf then yield the steam D3 from the first condensate A1. The vapor D3 from the first condensate separator A1 is fed via a so-called thermocompressor TK1 as low pressure steam according to the injector principle into the live steam / high pressure steam mixture D1,2. The steam D3 from the first condensate separator A1 has a lower pressure than the live steam / high pressure steam mixture D1,2.

The condensate K2 from the first condensate separator A1 can be pumped via a pump P1 to a steam generator. The steam generator may be, for example, a boiler house or other steam generator, which is not shown in this figure. Another part of the condensate K3 from the first condensate separator A1 is conveyed via another pump P2 for later steam generation directly or indirectly to the heat exchanger W1. Before the condensate K3 reaches the heat exchanger W1 from the first condensate separator, condensate K4 of a second condensate trap A2 is fed to this condensate K3. However, it would also be possible to use the condensate K3 of the first Condensate A1 first in the second condensate A2 to promote and then from there to promote the condensate mixture in the heat exchanger W1.

Before the condensate K3,4 reaches the heat exchanger W1 to the heat exchanger W1, it is guided to increase the pressure via a pump P3. The pump P3 conveys the condensate K3,4 and increases the pressure such that the condensate K3,4 does not evaporate in the heat exchanger W1 despite heating in the heat exchanger W1. The pressure of the heated condensate K * 3.4 from the heat exchanger W1 is only, and explicitly, degraded via a pressure-reducing element DR1. The pressure of the condensate K * 3.4 from the heat exchanger W1 is reduced above the pressure-reducing element DR1 such that the condensate K * 3.4 evaporates. The pressure-reducing element DR1 can be designed as a regulated valve or as a diaphragm. The resulting at the pressure reducing element DR1 steam is supplied to said second condensate A2. It may be reflected in the second condensate A2 of this resulting steam in part again as condensate, as must build for the eingependelten operating condition of the system, a pressure in the second condensate A2, which is large enough to overcome the back pressure of live steam D1 at the check valve R1. The exemplary check valve R1 is installed so that no steam from the live steam line D1 can get into the line of high-pressure steam D2; the direction of flow is from high pressure steam D2 to live steam D1. If the pressure in the second condensate separator A2 and thus the pressure of the high-pressure steam D2 have been set to a higher level than the pressure of the live steam D1, the high-pressure steam D2 generated flows via the check valve R1 into the live steam D1. The check valve R1 could also be designed as a controllable valve, which is a control deposited, which releases the valve only when electronically queried operating conditions and optionally drives the valve to certain degrees of opening.

The now possibly resulting steam / high pressure steam mixture D1,2 is now passed through a thermocompressor TK1. The steam D3 from the first condensate separator A1, whose pressure is inherently lower than the pressure of the live steam / high-pressure steam mixture D1,2, is likewise fed to said thermocompressor TK1 and is fed in according to the injector principle. As a result, steam D1,2,3 flows to the drying cylinder 1 ,

The 2 shows a further schematic representation of a preferred embodiment of the invention, which in the following features of 1 is different:
The condensate K3 from the first condensate separator A1 is required by a pump P2 to the heat exchanger W1. It eliminates in this embodiment, the pump P3 for pressure increase.

The condensate K4 from the second condensate A2 passes via a line to a pressure-reducing element DR2 before the first condensate A1, so that the condensate K4 can evaporate due to the pressure-reducing element DR2 and enters the condensate A1. A pump for the condensate K4 of condensate separator 2 after Kondensatabscheider 1 is not necessary, since the condensate K4 is pressed due to the higher pressure in the condensate separator 2 by itself in the direction of condensate 1. The pressure-reducing element DR2 can be designed as a valve or as a diaphragm.

The 3 shows a further schematic representation of a preferred embodiment of the invention, which in the following features of 1 is different:
The feed point, in which the high-pressure steam D2 is fed, is located in the line in which the steam mixture of live steam D1 and steam D3 is led out of the first condensate separator A1.

The 4 shows a further schematic representation of a preferred embodiment of the invention, which in the following features of 2 is different:
The feed point, in which the high-pressure steam D2 is fed, is located in the line in which the steam mixture of live steam D1 and steam D3 is led out of the first condensate separator A1.

The 5 shows a further schematic representation of a preferred embodiment of the invention, which in the following features of 1 is different:
The high pressure steam D2 is directed to other applications than the steam and condensate system shown here.

The 6 shows a further schematic representation of a preferred embodiment of the invention, which in the following features of 2 is different:
The high pressure steam D2 is directed to other applications than the steam and condensate system shown here.

The 7 shows a further schematic representation of a preferred embodiment of the invention, which in the following features of 1 is different:
The condensate K4 from the second condensate A2 is not merged with the condensate K3 from the first condensate A1, but passed into a third condensate A3. In the line of K4 is a pressure-reducing element DR3, preferably a controlled valve or an orifice, which allows the condensate K4 from the second condensate A2 relaxed in the third condensate A3 and thereby can evaporate again.

The resulting vapor D4 from the third condensate A3 is passed through a check element R2 in the line in which the vapor mixture of live steam D1 and steam D3 is guided out of the first condensate A1.

The condensate K5 from the third condensate A3 is guided into the line in which the condensate K3 is from the condensate A1. Accordingly, the condensate K5 and condensate K3 are led together to the heat exchanger.

The 8th shows a further schematic representation of a preferred embodiment of the invention, which in the following features of 2 is different:
The condensate K4 from the second condensate A2 is not merged with the condensate K3 from the first condensate A1, but passed into a third condensate A3. In the line of K4 is a pressure-reducing element DR3, preferably a controlled valve or an orifice, which allows the condensate K4 from the second condensate A2 relaxed in the third condensate A3 and thereby can evaporate again.

The resulting vapor D4 from the third condensate A3 is fed into the line in which the steam D3 is guided out of the condensate A1. The resulting vapor D4 from the third condensate A3 can also be led to other steam consumers, which are not shown in this figure.

The condensate K5 from the third condensate A3 is guided into the line that leads the condensate from condensate A1.

LIST OF REFERENCE NUMBERS

1

drying cylinders

100

Device for heat recovery

A1

First condensate separator

A2

Second condensate separator

A3

Third condensate separator

D1

live steam

D2

High pressure steam

D3

Steam from the first condensate separator

D4

Steam from the third condensate separator

D1,2

Live steam / high pressure steam mixture

D1,3

Live steam / steam from the first condensate mixture

D1,2,3

Mixture of D1, D2 and D3

DR1

Pressure reducing element

DR2

Pressure reducing element before the first condensate separator

DR3

Pressure reducing element before third condensate separator

F

Fibrous web

K1

Condensate / vapor mixture from the drying cylinder

K2

Condensate from the first condensate separator to the steam generator externally

K3

Condensate from the first condensate separator

K4

Condensate from the second condensate separator

K3,4

Condensate to the heat exchanger

K3,5

Condensate to the heat exchanger

K * 3.4

Condensate from the heat exchanger

K * 3.5

Condensate from the heat exchanger

K5

Condensate from the third condensate separator

L1

High-temperature hood

L2

gas burner

L3

circulation fan

L4

circulating air

L5

exhaust fan

L6

exhaust

L7

supply air

L8

Heat exchangers in general

L9

Exhaust bypass system

P1

Pump for condensate to the steam generator externally

P2

Pump for condensate from the first condensate separator

P3

Pump for pressure increase

R1

check valve

R2

check valve

TK1

thermal compressor

W1

heat exchangers

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• AT 506077 B1 [0003]
• DE 3501584 A1 [0004]

Claims (26)

Method for heat recovery for a dryer section of a machine for producing a fibrous web (F), in particular a paper, board or tissue web, wherein the fibrous web (F) is at least heated by a steam-heated drying cylinder ( 1 ) and at least one high-temperature hood (L1) is dried with hot air, wherein the at least one drying cylinder ( 1 ) is at least partially supplied with live steam (D1), wherein the condensate / vapor mixture (K1) of the at least one drying cylinder ( 1 ) is fed to a Kondensatabscheider (A1), wherein the steam (D3) from the condensate (A1) to the live steam (D1) or a live steam / high pressure steam mixture (D1,2) is supplied, wherein at least a portion of the condensate (K3) from the at least one drying cylinder ( 1 ) downstream condensate (A1) is a heat exchanger (W1) in the exhaust air stream (L6) of the high-temperature hood (L1) is supplied, and wherein the condensate (K3,4) is heated there and energy of the exhaust air (L6) receives, then by a pressure-reducing Element (DR1) is relaxed and thereby at least partially evaporated again, characterized in that the heated by the heat exchanger (W1) condensate (K * 3.4), which subsequently relaxed by a pressure-reducing element (DR1) and thereby at least partially has been vaporized, at least partially fed as high-pressure steam (D2) in a steam line or a vapor vessel whose pressure is higher than the pressure of the at least one drying cylinder ( 1 ) downstream condensate separator (A1). A method according to claim 1, characterized in that the by the pressure reducing element (DR1) re-evaporated condensate (K * 3,4) is fed to a second condensate separator (A2). A method according to claim 1 or 2, characterized in that the steam line or the steam tank, in which the high-pressure steam (D2) is fed, is the line in which live steam (D1) is guided. A method according to claim 1 or 2, characterized in that the steam line or the steam tank, in which the high-pressure steam (D2) is fed, is the line in which the steam mixture of live steam (D1) and steam (D3) from the at least one Drying cylinder ( 1 ) is guided downstream condensate. Method according to one of claims 2 to 4, characterized in that at least a part, preferably the largest part of the condensate (K4) of the second condensate (A2) is fed back to the heat exchanger (W1). Method according to one of claims 2 to 4, characterized in that at least a part, preferably the largest part of the condensate (K4) of the second condensate (A2) the condensate (A1), which is also the condensate / vapor mixture (K1) of at least a drying cylinder ( 1 ) is supplied via a pressure-reducing element (DR2), so that the condensate (K4) of the second condensate separator (A2) can evaporate via this pressure-reducing element (DR2). Method according to one of claims 2 to 4, characterized in that at least a part, preferably the largest part of the condensate (K4) of the second condensate (A2) a third condensate (A3) via a pressure-reducing element (DR3), which a diaphragm or preferably a valve can be supplied. A method according to claim 7, characterized in that the steam line or the steam tank, into which the steam (D4) of the third condensate (A3) is fed, is the line in which the steam mixture of live steam (D1) and steam (D3) the at least one drying cylinder ( 1 ) downstream condensate (A1) is performed. Process according to Claim 7, characterized in that the vapor (D4) of the third condensate separator (A3) communicates with the vapor (D3) of the at least one drying cylinder (A3). 1 ) downstream condensate (A1) is connected. Method according to one of the preceding claims, characterized in that as a pressure-reducing element (DR1) after the heat exchanger (W1) to relax the condensate (K * 3,4), a valve is used. Method according to one of claims 2 to 9 and claim 10, characterized in that the valve (DR1) is controlled according to a pressure setpoint, the pressure actual value of which represents the pressure at the second condensate separator (A2). A method according to claim 11, characterized in that the pressure setpoint preferably automatically according to the Druckist- or pressure setpoint in the steam line or the steam tank whose pressure is higher than the pressure of the at least one drying cylinder ( 1 ) downstream condensate (A1) is generated. Method according to one of the preceding claims, characterized in that prior to feeding the generated high-pressure steam (D2) into the steam line or the steam tank whose pressure is higher than the pressure of the at least one drying cylinder ( 1 ) is ensured by at least one check valve (R1) that no steam from the steam line or the steam tank, the pressure of which is higher than the pressure of the at least one drying cylinder ( 1 ) downstream condensate separator (A1), in the line of high-pressure steam (D2) passes. Method according to one of the preceding claims, characterized in that the heat exchanger (W1) is preceded by a pump (P3) which generates a sufficiently high pressure to prevent evaporation of the condensate (K3,4) in the heat exchanger (W1). Contraption ( 100 ) for heat recovery for a dryer section of a machine for producing a fibrous web (F), in particular a paper, board or tissue web, in which a fibrous web (F) is dried, consisting of at least one steam-heated drying cylinder ( 1 ) and at least one high-temperature hood (L1) which is acted upon by hot air, wherein the at least one drying cylinder ( 1 ) is at least partially supplied with live steam (D1), wherein the condensate / vapor mixture (K1) of the at least one drying cylinder ( 1 ) is fed to a condensate (A1), wherein the steam (D3) from the condensate (A1) to the live steam (D1) or a live steam / high pressure steam mixture (D1,2) is supplied, wherein at least a portion of the condensate (K3) from the at least one drying cylinder ( 1 ) downstream condensate (A1) is a heat exchanger (W1) in the exhaust air stream (L6) of the high-temperature hood (L1) is supplied, and wherein the condensate (K3,4) is heated there and energy of the exhaust air (L6) receives, then by a pressure-reducing Element (DR1) is relaxed and thereby at least partially evaporated again, characterized in that the heated by the heat exchanger (W1) condensate (K * 3.4), which subsequently relaxed by a pressure-reducing element (DR1) and thereby at least partially is vaporized, is connected via at least one line as high-pressure steam (D2) to a steam line or a steam tank, the pressure of which is higher than the pressure of the at least one drying cylinder ( 1 ) downstream condensate separator (A1). Device according to Claim 15, characterized in that the pressure-reducing element (DR1) is followed by a second condensate separator (A2) via a line. Apparatus according to claim 15 or 16, characterized in that the steam line or the steam tank, in which the high-pressure steam (D2) is fed, is the line in which live steam (D1) is guided. Apparatus according to claim 15 or 16, characterized in that the steam line or the steam tank, in which the high-pressure steam (D2) is fed, is the line in which the steam mixture of live steam (D1) and steam (D3) from which the at least one Drying cylinder ( 1 ) is guided downstream condensate. Device according to one of claims 16 to 18, characterized in that the line which condensate (K4) from the second condensate separator (A2) leads, is connected to the line to the heat exchanger (W1). Device according to one of claims 16 to 18, characterized in that the line leading condensate (K4) from the second condensate (A2), with the condensate (A1), which is also the condensate / vapor mixture (K1) of at least one Drying cylinder ( 1 ), wherein there is a pressure-reducing element, preferably a valve or a diaphragm, in this line. Device according to one of claims 16 to 18, characterized in that the line which condensate (K4) from the second condensate separator (A2) leads to a third condensate separator (A3) is connected, wherein in this line, a pressure-reducing element, preferably a Valve or aperture is located. Apparatus according to claim 21, characterized in that the line which leads steam (D4) from the third condensate separator (A3), is connected to the steam line, the steam mixture of live steam (D1) and steam (D3) from the at least one Drying cylinder ( 1 ) leads downstream condensate. Apparatus according to claim 21, characterized in that the conduit which carries steam (D4) from the third condensate separator (A3) is connected to the conduit which separates the steam (D3) from the at least one drying cylinder (D3). 1 ) leads downstream condensate. Device according to one of claims 15 to 23, characterized in that as a pressure-reducing element after the heat exchanger (W1), a valve (DR1) is used. Device according to one of claims 15 to 23, characterized in that in the conduit of the high-pressure steam (D2), before the connection to the steam line or a steam tank whose pressure is higher than the pressure of the at least one drying cylinder ( 1 ) downstream condensate (A1), a non-return element, preferably a check valve (R1), is installed. Device according to one of claims 15 to 25, characterized in that the heat exchanger (W1) is preceded by a pump (P3) which is capable of generating a pressure of the condensate (K3,4) to the heat exchanger (W1) is higher than the pressure at which the condensate (K3,4) would evaporate in the heat exchanger (W1).

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