WO2016070977A1

WO2016070977A1 - Method for operating a regenerative burner system, and regenerative burner system

Info

Publication number: WO2016070977A1
Application number: PCT/EP2015/002168
Authority: WO
Inventors: Martin Schöninger
Original assignee: Linde Aktiengesellschaft
Priority date: 2014-11-03
Filing date: 2015-10-29
Publication date: 2016-05-12

Abstract

The present invention relates to a method for operating a regenerative burner system (100) having a number of regenerative burners (110, 120) which each comprise a bidirectionally operable line section (113, 123) and which are operated alternately in a first operating mode and in a second operating mode, wherein, in the first operating mode, a fuel (132) is burned in a combustion chamber (101) with a combustion assistance gas (131), the latter being fed partially via the bidirectionally operable line section (113, 123), such that a combustion gas (141) is obtained, and in the second operating mode, the combustion exhaust gas (141) is discharged out of the combustion chamber (101) via the bidirectionally operable line section (113, 123), wherein, at the start of the first operating mode, as combustion assistance gas, use is made of a residual amount of the combustion exhaust gas (141) which is present in the respective bidirectionally operable line section (113, 123) after the second operating mode, and of at least one oxygen-rich auxiliary gas.

Description

description

Method for operating a regenerative burner system and

Regenerativbrennersvstem

The invention relates to a method for operating a regenerative burner system with a number of regenerative burners, each comprising a bidirectionally operable line section and operated alternately in a first operating mode and a second operating mode, wherein in the first operating mode, a fuel supplied with a bidirectionally operable line section Combustion support gas is burned to obtain a combustion exhaust gas in a combustion chamber, and in the second mode of operation

Combustion exhaust gas is discharged from the combustion chamber via the bidirectionally operable line section.

State of the art

In regenerative burner systems can burn with a

Energy recovery can be performed. Regenerative burner systems may include a number of regenerative burners that operate alternately in a first and a second mode of operation. In a first number of

Regenerative burners operated in the first mode of operation may have a

Combustion are carried out in a combustion chamber. In this case, fuel can be burned while supplying a combustion support gas into the combustion chamber. At the same time, in a second number of regenerative burners operating in the second mode of operation, a combustion exhaust gas may

Burning be discharged from the combustion chamber.

In general, each of the regenerative burners has a common supply and discharge line for the combustion support gas or the combustion exhaust gas in the form of a line section of a gas line, here as "bidirectionally operable

Depending on the operating mode, either the combustion assisting gas for combustion can be supplied to the respective regenerative burner via this bidirectionally operable line section, or Are discharged combustion exhaust gas. The fuel is usually supplied via one or more separate lines.

After a change from the second to the first operating mode, a so-called rinsing phase is usually carried out at the beginning of the first operating mode. In the course of this purge phase, a residual amount of the combustion exhaust gas, which can still be operated in the respective bidirectional mode after the second operating mode

Line section is located, first removed from this. It can the

corresponding bidirectionally operable line section, for example, be flushed with air.

During this rinsing phase, the corresponding regenerative burner can usually not be used for combustion. Only when the remainder of the

Combustion exhaust gas completely from the bidirectionally operable

Line section is removed, combustion assist gas is again supplied via the bidirectionally operable line section and the corresponding regenerative burner is fired. This is time consuming and leads to inhomogeneities in the thermal output of a corresponding regenerative burner system. Furthermore, can be operated by flushing the bidirectional

Line section with air an undesirably high oxygen content in the

Combustion exhaust gas in the course of the subsequent combustion result. Although the best possible oxygen content in the exhaust gas of about 2% can be set before changing the operating modes. Immediately after the rinsing phase, the

However, oxygen content in the exhaust gas can be up to about 12%.

It is therefore desirable to provide an improved way of operating a regenerative burner system. Disclosure of the invention

According to the invention, a method for operating a

Regenerative burner system and a corresponding regenerative burner system proposed with the features of the independent claims. advantageous Embodiments emerge from the respective subclaims and the following description.

The regenerative burner system includes a number of regenerative burners each including a bidirectionally operable line section and operated alternately in a first mode of operation and a second mode of operation. In the first mode of operation, a combustion assisting gas is at least partially supplied via the bidirectionally operable line section and combusted with a fuel also supplied, for example, via one or separate lines to obtain a combustion exhaust gas in a combustion chamber. In the second operating mode, the combustion exhaust gas is discharged from the combustion chamber via the bidirectionally operable duct section. As fuel, for example, natural gas can be used. For example, air may be supplied as combustion assist gas.

A first number of these regenerative burners are operated in the first operating mode while at the same time a second number of these regenerative burners are operated in the second operating mode. After predetermined time intervals, a change of the operating modes is carried out in each case. After this change, the first number of regenerative burners is accordingly operated in the second operating mode, the second number in the first operating mode. Such a change of

Operating modes are in particular carried out in each case at constant time intervals, for example in each case after a time interval between 30 s and 120 s. The regenerative burner system has, in particular, a gas supply for supplying the combustion support gas and possibly the fuel. The gas supply, for example, separate lines, which typically open directly into the corresponding burner, with the fuel on the one hand and the

On the other hand, apply combustion assist gas. In particular, the regenerative burner system has a gas discharge for discharging the

Combustion exhaust gas via the bidirectionally operable line section.

The respective bidirectionally operable line sections are thus designed, in particular, as common supply and discharge lines and are furthermore connected, in particular in each case, to the gas supply and the gas removal. Depending on the operating mode can the respective regenerative burners are supplied via the respective bidirectionally operable line section either the fuel for the combustion or the combustion exhaust gas are discharged from the combustion chamber. Upstream of the respective bidirectionally operable line sections of

different regenerative burner is in particular each a suitable switching element arranged, for example, a flap or a valve. One

corresponding switching element may also have a plurality of such valves or valves. By appropriate, i. In particular synchronized with the aforementioned operating modes, switching or driving this switching element can between the supply of the combustion support gas and the discharge of the

Combustion exhaust gas can be changed over the respective bidirectionally operable line section by this is optionally connected to the gas supply or the gas discharge. Thus, it is possible to switch between the first and the second operating mode of the respective regenerative burner.

Corresponding switching elements may also be provided in one or more lines for the fuel and synchronously with the switching elements for the

Combustion support gas and the combustion exhaust gas are operated. The bidirectionally operable line section is in particular a section of a

Gas line between this switching element and the respective regenerative burner itself or its terminal end.

According to the invention at the beginning of the first operating mode as

Combustion assist gas instead of a separately supplied

Combustion support gas such as air has a residual amount of

Combustion exhaust gas, which is present in the respective bidirectionally operable line section after the second operating mode, and at least one

oxygen-rich additional gas used. For this purpose, the

Regenerative burner system an additional gas supply to feed the

oxygen-rich additional gas. This supplemental gas is mixed with the remaining amount of the combustion exhaust gas existing in the respective bidirectionally operable duct section after the second operation mode, and therefore has an oxygen content sufficient or specifically set for combustion. The additional gas is supplied in particular to a region (immediately) in front of the respective regenerative burner, ie upstream of the respective regenerative burner. In particular, additional gas is at least partially supplied to the bidirectionally operable line section. As a result, the additional gas can be operated bidirectionally with the residual amount of combustion exhaust gas

Mix pipe section. However, a feed is also downstream of one

corresponding regenerative burner, i. in the combustion chamber, but in the immediate vicinity of the burner, possible. Advantages of the invention

With the invention, it is no longer necessary to carry out a rinsing phase at the beginning of the first operating mode. The invention makes it possible, also and immediately at the beginning of the first operating mode combustion in the respective

To perform regenerative burner. It does not have to wait until the

Residual amount of the combustion exhaust gas is completely removed from the bidirectionally operable line section to a respective regenerative burner

To carry out combustion. Instead, the remaining amount of

Combustion gases themselves are used to in the respective

Regenerative burner to perform a combustion. In particular, combustion can already be started in the respective regenerative burner as soon as the corresponding switching element in the respective gas line is actuated.

This results in a particularly homogeneous heat output. By the oxygen-rich additional gas physical and / or chemical properties of the residual amount of the combustion exhaust gas can be changed or specifically influenced. In particular, the properties of the residual amount of the combustion exhaust gas are changed by the additional gas such that the residual amount of the combustion exhaust gas is suitable for combustion, or that

corresponding combustion assist gas may assist combustion of the fuel.

By combustion with the residual amount of the combustion exhaust gas and the additional gas, in particular the oxygen content in the combustion exhaust gas can be influenced or adjusted, which in the course of this first operating mode is generated by the respective regenerative burner in the combustion chamber. In particular, this oxygen content can be kept very uniform over the entire first operating mode, without leading to peaks of the oxygen content at the beginning thereof (due to a purging with air). Furthermore, the

Oxygen content should be kept as low as possible, especially at about 2%.

By the invention, an increase in performance of the regenerative burner system can be achieved in total and the energy efficiency can be increased. Furthermore, a slight increase in a proportion of carbon dioxide in the

Combustion exhaust gas can be achieved during the first operating mode.

Advantageously, the oxygen-rich additional gas at the end of the second

Operating mode of the residual amount of the combustion exhaust gas fed. The

Oxygen-rich additional gas is thus supplied, while the bidirectionally operable line section is still flowed through with the combustion exhaust gas. In particular, the oxygen-rich additional gas is fed directly or at least partially into the bidirectionally operable line section. The

Combustion exhaust gas and the oxygen-rich additional gas can be mixed over the entire length of the bidirectionally operable line section, up to the appropriate switching element, which is arranged upstream of the bidirectionally operable line section.

When switching between the second and the first operating mode, in which the switching element is switched accordingly, the volume flow comes out

Combustion exhaust gas and oxygen-rich additional gas to a standstill. As a result, combustion exhaust gas and oxygen-rich additional gas are mixed together again. At the beginning of the subsequent first operating mode mix

Combustion exhaust gas and oxygen-rich additional gas again in the bidirectionally operable line section between switching element and burner. In this way, a homogeneous, best possible mixture of the combustion exhaust gas and the oxygen-rich additional gas can be achieved.

Alternatively or additionally, the oxygen-rich additional gas is advantageously fed to the remainder of the combustion exhaust gas at the beginning of the first operating mode. When the supplemental gas is supplied only at the beginning of the first operating mode In particular, first a predetermined time interval can be waited for before the corresponding burner is fired with the mixture of combustion exhaust gas and additional gas. Thus, it can be ensured, in particular, that the combustion exhaust gas and the oxygen-rich additional gas mix homogeneously and as optimally as possible.

Preferably, in the further course of the first operating mode as

Combustion support gas again the externally supplied

Combustion assist gas, for example, air, used when no

Residual amount of the combustion exhaust gas in the respective bidirectionally operable line section longer exists. When the oxygen-rich additive gas is supplied at the beginning of the first operation mode, the supply of the additional gas is stopped, especially at this time. The fuel is then, for example, with pure air, which is supplied as combustion support gas via the bidirectionally operable line section, by the corresponding

Renewable burners burned in the combustion chamber. The corresponding

Regenerative burner is normally fired according to the first mode of operation.

In the context of the present invention, pure oxygen, oxygen-enriched air or so-called "pure oxygen" is preferably selected from a

Air separation plant fed as additional gas. In this context, "pure oxygen" is understood as meaning oxygen having a purity of preferably at least 90% or 99%, more preferably of at least 99.5%, further preferably with a maximum impurity of 1 ppm The residual amount of combustion exhaust gas can thus be enriched for combustion by the respective regenerative burner.

Advantageously, an oxygen content of the combustion support gas is adjusted to a predetermined value by the oxygen-rich additional gas. Through this oxygen content, the combustion of the remaining amount of

Combustion exhaust gas affects or be adjusted. Furthermore, the oxygen content in the combustion exhaust gas can thus also be influenced or adjusted. which is generated in the course of combustion by the respective regenerative burner in the combustion chamber. Preferably, the oxygen content of the

Combustion assist gas adjusted to a value between 15% and 25%, more preferably in particular to a value between 20% and 22%, preferably to a value of substantially 20.9%.

Preferably, in the bidirectionally operable line section

Heat storage elements or regenerator arranged, for example, regenerator balls. Such heat storage elements may for example be made of aluminum oxide (Al ₂ 0 ₃ ) or silicon carbide (SiC). By such

Heat storage elements can be performed in the regenerative burner system combustion with energy recovery.

If combustion exhaust gas is discharged via the bidirectionally operable line section in the second operating mode, the heat storage elements are preferably heated by the exhaust gas exhausted or by the thermal energy of the combustion exhaust gas. This is preferred

Combustion assist gas in the first mode of operation through this

heated heat storage elements in the bidirectionally operable

Line section heated. The heated heat storage elements release thermal energy to the combustion support gas. Thus, the combustion assistance gas for the combustion can be preheated.

The invention further relates to a regenerative burner system with a number of regenerative burners. Embodiments of this invention

Regenerative burner will be apparent from the above description of the

inventive method in an analogous manner.

figure description

The invention and its advantages will now be explained with reference to the accompanying drawings. In this shows schematically a preferred embodiment of a regenerative burner system according to the invention and Figure 2 schematically shows a preferred embodiment of a method according to the invention as a block diagram. FIG. 1 shows a preferred embodiment of a device according to the invention

Regenerative burner system shown schematically and designated 100.

The regenerative burner system has two regenerative burners 110 and 120, which are arranged on a combustion chamber 101. The regenerative burners 110 and 120 are connected to a gas line 111 and 121, respectively.

Before the regenerative burners 1 10 and 120 each heat storage elements 1 14 and 124 are arranged in the respective gas line 11 1 and 121, for example, regenerator balls of alumina (Al ₂ 0 ₃ ).

In the gas lines 111 and 121 each one designed here as a flap switching element 1 12 and 122 respectively. A portion of the respective gas line 1 11 and 121 between the respective flap 112 and 122 and the respective

Regenerative burner 110 or 120 is designed as a bidirectionally operable line section 113 or 123 of the respective gas line 1 1 1 or 121.

The gas lines 111 and 121 are connected to a gas supply 130 and a gas discharge 140, respectively. When the respective flap 112 or 122 is switched to a first position, the respective regenerative burner 110 or 120 through the gas supply 130 in the course of a first operating mode, for example, air as

Combustion support gas 131 is supplied via the respective gas line 111 and 121, respectively. In addition, natural gas is supplied as fuel 132 to the respective regenerative burner 110 or 120 via a separate fuel line or a separate fuel lance 170 or 180 in the first operating mode.

In the first operating mode, combustion of the mixture of natural gas 132 and, for example, air 131 in the combustion chamber 101 is performed by the respective regenerative burner 110 or 120. In the combustion chamber 101, a combustion exhaust gas 141 results. This combustion exhaust gas 141 is discharged in the course of a second operating mode by the gas discharge 140 via the respective gas line 1 11 and 121 and thus also the bidirectionally operable line sections 113 and 123 from the combustion chamber 101 when the flap 1 12 or 122 in a second Position is switched.

In FIG. 1, the regenerative burner 110 is shown in the first operating mode and the regenerative burner 120 in the second operating mode.

The regenerative burner system 100 further includes an auxiliary gas supply 160. This additional gas supply 160 comprises two oxygen lances 161 and 162, respectively, which are arranged on the bidirectionally operable line sections 113 and 123, respectively. About these oxygen lances 161 and 162, respectively, an oxygen-rich additional gas can be fed into the respective bidirectionally operable line section 113 and 123, respectively. In particular, pure oxygen with a purity of at least 99.5% is fed in as such oxygen-rich additional gas. As mentioned, corresponding oxygen lances can also be introduced into the combustion chamber 101, but in

Close proximity of the regenerative burner 110 and 120, open.

The regenerative burner system 100 furthermore has a control unit 150, which is set up to carry out a preferred embodiment of a method according to the invention. This preferred embodiment is shown schematically in Figure 2 as a block diagram.

In a step 201, the regenerative burner 110 is operated in the first operating mode and the regenerative burner 120 in the second operating mode, as shown in FIG.

In a step 202, at the end of the second operating mode of the

Regenerative burner 120 through the additional gas supply 160 via the oxygen lance 162 pure oxygen or another oxygen-rich gas, hereafter briefly

"Oxygen", fed into the bidirectionally operable line section 123.

Subsequently, a change of the operating modes is performed. The feed of the oxygen is stopped, the regenerative burner 110 is now operated in the second mode of operation and the regenerative burner 120 in the first

Operation mode. For this purpose, the flap 112 from the first to the second Switched position and the flap 122 from the second position to the first. In the bidirectionally operable line section 123 of the gas line 121 is after

Switching the position of the flap 122 still a residual amount of

Combustion exhaust gas 141 and the supplied oxygen before.

This residual amount of the combustion exhaust gas 141 and the injected oxygen are supplied to the regenerative burner 120 at the step 203 at the beginning of the first operation mode of the regenerative burner 120 through the bidirectionally operable line portion 123 of the gas conduit 121. This supplied oxygen and the residual amount of the combustion exhaust gas 141 are referred to as

Combustion assist gas used and burned by the regenerative burner 120 at the beginning of the first mode of operation. By the supplied oxygen, an oxygen content of this combustion assist gas is set to a predetermined value, for example, 20.9%.

In a step 204, there is no remaining amount of the combustion exhaust gas 141 in the bidirectionally operable line section 123 of the gas pipe 121. In step 204, in the further course of the first operating mode, natural gas 132 and air 131 are burned by the regenerative burner 120.

After a predetermined time interval of, for example, 30 s after the change of the operating modes according to step 202, a change of the operating modes is carried out again in step 205. Before this change, in step 205, oxygen is initially fed into the bidirectionally operable line section 113 at the end of the second operating mode of the regenerative burner 110 by the additional gas feed 160 via the oxygen lance 161. Subsequently, the flap 1 12 is switched back to the first position, the flap 122 back to the second position and the oxygen lance 161 no more oxygen is fed. The regenerative burner 110 is now back in the first

Operating mode operated and the regenerative burner 120 again in the second operating mode.

After this switching is in step 206 at the beginning of the first operating mode of the regenerative burner 110 now in the bidirectionally operable line section 1 13th the gas line 111 before a residual amount of the combustion exhaust gas 141 and the supplied oxygen.

This residual amount of the combustion exhaust gas 141 and the oxygen are supplied in step 206 at the beginning of the first operating mode of the regenerative burner 110 through the bidirectionally operable line section 1 13 of the gas line 1 11 in the direction of the regenerative burner 110. This supplied oxygen and the residual amount of the combustion exhaust gas 141 are used as the combustion assist gas and burned by the regenerative burner 110 at the beginning of the first operation mode. Also in this case, an oxygen content of this combustion assist gas is adjusted to 20.9% by the supplied oxygen.

As soon as there is no remaining amount of the combustion exhaust gas 141 in the bidirectionally operable line section 13 of the gas line 111, step 101 is performed again, and in the course of the first operating mode, natural gas 132 and air 131 are burned by the regenerative burner 110.

After the predetermined time interval of 30 s after the change of the operating modes according to step 205, the change of the operating modes according to step 202 is performed again.

LIST OF REFERENCES

100 regenerative burner system

101 combustion chamber

110 regenerative burners

111 gas line

1 12 flap, switching element

1 13 bidirectionally operable line section

1 14 heat storage elements

120 regenerative burners

121 gas line

122 flap, switching element

123 bidirectionally operable line section

124 heat storage elements

130 gas supply

131 air, combustion support gas

132 natural gas, fuel

140 gas discharge

141 combustion exhaust gas

150 arithmetic unit

160 additional gas supply

161 oxygen lance

162 oxygen lance

170 fuel line, fuel lance

180 fuel line, fuel lance

201 process step

202 process step

203 process step

204 process step

205 process step

206 process step

Claims

claims

A method of operating a regenerative burner system (100) comprising a plurality of regenerative burners (110, 120), each comprising a bidirectionally operable line section (1, 13, 123) and operated alternately in first and second modes of operation, wherein in the first one

Operating mode, a fuel (132) with an at least partially supplied via the bidirectionally operable line section (113, 123)

Combustion assist gas (131) is burned to obtain a combustion exhaust gas (141) in one combustion chamber (101), and in the second

Operating mode the combustion exhaust gas (141) via the bidirectionally operable line section (113, 123) is discharged from the combustion chamber (201) (201, 204), characterized in that at the beginning of the first operating mode as combustion support gas, a residual amount of the combustion exhaust gas (141) after the second

Operating mode in the respective bidirectionally operable line section (113, 123) is present, and at least one oxygen-rich additional gas can be used (203, 206).

The method of claim 1, wherein the oxygen-rich additional gas at the beginning of the first operating mode and / or at the end of the second operating mode of the

Residual amount of the combustion exhaust gas is fed (202, 205).

A method according to claim 1 or 2, wherein in the further course of the first

Operating mode is used as the combustion assist gas (131) air when there is no remaining amount of the combustion exhaust gas in the respective bidirectionally operable line section (113, 123) more (201 204).

A method according to any one of the preceding claims, wherein pure oxygen or oxygen-enriched air is used as the oxygen-rich make-up gas (202, 205).

5. The method of claim 4, wherein the pure oxygen or the oxygen-enriched air is fed through an oxygen lance (161, 162) (202, 205). 6. The method according to any one of the preceding claims, wherein by the

oxygen-rich additional gas an oxygen content of the

Combustion assist gas is set to a predetermined value.

7. The method according to claim 6, wherein the oxygen content of the

Combustion assist gas is adjusted to a value between 15% and 25%, in particular to a value between 20% and 22%, more particularly to a value of substantially 20.9%.

8. The method according to any one of the preceding claims, wherein in the second

Operating mode heat storage elements (114, 124) in the bidirectionally operable line section (1 13, 123) through the outgoing

Combustion exhaust gas (141) are heated.

9. The method of claim 8, wherein in the first mode of operation, the fuel (132) and / or at least a portion of the combustion assisting gas (131) are heated by the heated heat storage elements (1,14,124) in the bidirectionally operable conduit section (113,123) ,

A regenerative burner system (100) having a number of regenerative burners (110, 120),

characterized in that

the regenerative burner system (100) comprises an auxiliary gas supply (160) for supplying an oxygen-rich additional gas and a control unit (150) which is adapted to carry out a method according to one of the preceding claims.

11. A regenerative burner (100) according to claim 10, wherein the additional gas supply (160) comprises at least one oxygen lance (161, 162).