DE102009014223A1 - Firing system of a designed for the oxyfuel operation steam generator - Google Patents

Abstract

In a steam generator with fossil-fired combustion chamber and at least one burner level and / or at least one top air nozzles and / or side wall nozzles having plane with connected feeding means (9, 10, 11, 12) and / or supply lines (2, 4, 5, 9a-9d, 10a-10d, 11a-11d, 12a-12d) by / by which (r) the combustion chamber combustion and / or oxidation oxygen-promoting gas streams are supplied, a solution is to be created by means of which in oxyfuel operation of the steam generator in the partial load range undesirable Avoid oxygen levels in flue gas. This is achieved in that the supply means (9, 10, 11, 12) and / or the supply lines (2, 2a-2d, 4, 5, 9a-9d, 10a-10d, 11a-11d, 12a-12d) in such a way are formed, that at least a portion of each of a burner or nozzle level and / or in each case a burner (1) or a nozzle (13) supplied gas streams individually and / or separately acted upon by the other gas streams with oxygen and / or individually and / or or separately from the other gas streams in terms of their oxygen content or their oxygen concentration and / or the oxygen mass flow promoted with them is adjustable.

Description

The Invention is directed to a steam generator with fossil fuel fired Firebox and at least one burner level and / or an upper air nozzles and / or side wall nozzles having plane with attached Supply means and / or supply lines, by / means which (s) the combustion chamber and / or oxidation oxygen promoting Guest streams can be fed.

conventional fossil, d. H. especially with coal, fired large steam generators have a firebox where the fossil fuel burned becomes. These firing systems consist of several superimposed arranged burner levels and other nozzle levels, through which, for example, upper air, fog or other air the Firebox is supplied. The burner levels exist from a variety of burners, which have a conveyor cross-section have, by which in coal-fired burners a subsidized with supporting air Kohlemassenstrom funded by the burner and at the outlet end of the mouth is ignited. to Support combustion, one burner points another Flow and delivery cross sections through which through core air, secondary air or tertiary air in support of the combustion process and for example a particular low NOx combustion through the burner promoted to the mouth-side outlet end becomes. The number of flow cross-sectional openings depends on the type of burner and depending on the burner type different, so not in any case conveyor cross sections for transporting air, secondary and tertiary air must be present.

in principle but it is so that in addition to the fuel-promoting Cross section also further, combustion and / or oxidation oxygen in the firebox conveying cross sections available. The trained in a steam generator respectively Burner levels and / or upper air or sidewall nozzles having Layers are then connected to supply means and / or Supply lines provided by which or by which Combustion and / or oxidation oxygen supplied to the furnace becomes. It is in terms of piping in practice So far, that of one, the coal as fossil fuel aufmahlenden Mill each burner all a burner level or at least all burners on one side of a burner level together over a mill discharge line, which then followed Branched, with the fossil fuel (coal) and this promoting Gas flow (carrying air) are supplied. Furthermore, it is in practice usual in such large steam generators, that the supply of the other existing flow and / or conveying cross sections in the individual burner levels or the additional top air or side wall nozzles having levels of a common, heated combustion air feeding supply line branching supply lines he follows. This is the oxygen content of in these lines promoted gas flow due to the diversion of all lines Once established by an originating authority and at all in the Firebox opening flow and / or flow cross sections equal. Only the amount of each funded gas stream is regulated by flaps or similar devices. at These known large steam generators is also the oxygen content in the outgoing from the mill flow for all burners connected to the respective mill are the same.

If such a system is now driven in the partial load range will be individual burner levels or individual burners shut off while a remaining number of burners or burner levels continue to operate stay. So that it still prevails in the firebox due to high temperatures do not damage the parked Burner comes, these must be cooled. These Cooling is achieved by continuing to contain oxygen Gas flows through at least part of the in the respective Burner existing flow and / or cross sections is promoted and possibly also by existing top air nozzles or sidewall nozzles conveyed into the furnace becomes. In addition to cooling is such a promotion of oxygen-containing gas streams also necessary to in the Steam generators, d. H. in the boiler, a necessary minimum amount of flue gas to maintain that in the steam generator, especially in the high pressure area and in the reheater area, necessary temperatures to reach. These in the partial load range even when the burners are switched off the amount of oxygen supplied to the firebox now that the total oxygen supply made available is much higher than procedural for a complete combustion of the in the active burners fuel required and necessary.

Furthermore, it is known from trade publications that power plants are driven with large steam generators to reduce CO ₂ emissions in so-called oxyfuel operation. In oxyfuel operation, only pure oxygen is supplied to the burners as "combustion air" and the resulting CO ₂ -containing flue gas is returned to the burners, but also to the mills, and in particular by appropriate adjustment of CO ₂ / O ₂ mixtures in the furnace adjusted the required steam parameters in order to operate such a power plant optimally. In these operated in the oxyfuel operation power plants, the CO ₂ reduction of the exhaust gas exhausted in the end he thus It is sufficient that the CO _{2 is} removed from the flue gas and compressed in particular for subsequent storage. For this final flue gas treatment process, it is necessary that the oxygen content in the flue gas is minimized. Oxygen at this point represents an undesirable pollution of the flue gas and makes direct storage of the compressed CO ₂ impossible.

The design of such large steam generator now takes place so that an amount of oxygen / oxygen concentration is provided, as required by the requirements of Brennerverfahrenstechnik for a complete, low-NO _x combustion of the fuel is necessary. The amount of oxygen necessary for complete, CO-poor combustion is optionally added as so-called burn-out air at the end of the furnace in transition to the actual steam generator. When oxy fuel operation in the partial load range now the problem arises that when switching off a burner level then due to the above-described necessary cooling of the individual burner due to the same for all similar flow and / or opening cross sections by relying on a single common original delivery line oxygen content of respective gas flows present an oxygen supply in the furnace, which goes beyond the necessary for a stoichiometric combustion of the fuel supplied. As a result, oxygen is present as an impurity in the flue gas, which impairs or even makes impossible the proposed CO ₂ separation. A conceivable reduction of all relevant oxygen-containing gas streams, ie the core air and / or secondary air and / or tertiary air, with respect to their oxygen content or their oxygen concentration in order to then produce the total allowable total amount of oxygen in the furnace to avoid O ₂ -Anteilen in the exhaust gas would then but due to the existing line interconnection lead to a low oxygen concentration would be available to the active burners and thus a stable combustion of the fuel at these burners in the partial load range could not be ensured. Therefore, it would be problematic according to previous findings to operate conventional, known from the prior art large steam generator after the oxyfuel process when a partial load range is reached, which would require the shutdown of a burner level or part of a burner level or would allow. In order not to jeopardize the proposed CO ₂ capture, such power plants would therefore always have to be operated in such a way that all burners are in operation, even if it is not necessary for this entire load to be made available. Consequently, it would be in the power plants known from the prior art so that the partial load capacity of a thus operated in the oxyfuel process large steam generator would be severely limited, that required for CO ₂ capture CO ₂ purity in the exhaust gas below a load range at which one burner level can or should be switched off, would no longer exist.

Of the Invention is based on the object, a solution for to provide the problem described above.

at a steam generator of the type described is this task solved according to the invention that the supply means and / or supply lines such are formed, that at least a part of each of a burner or nozzle plane and / or in each case a burner or a nozzle each supplied gas flows individually and / or be acted upon by oxygen separately from the other gas streams and / or individually and / or separately from the other gas streams be acted upon by oxygen and / or individually and / or separately from the other gas streams in terms of their oxygen content or their oxygen concentration and / or the one promoted with them Oxygen mass flow is adjustable.

The Invention thus turns from the previous design principle all with combustion and / or oxidation oxygen for providing the combustion process in the firebox Gas streams from a common source line, in which by the gas flow promoted therein, the oxygen content is destined to dine. Instead, the invention provides that at least a part of the cross sections and / or opening cross sections individually and separately and thus also independently of others Gas streams can be acted upon by a gas stream. The easiest way is if this is realized by a separate own supply line, in the example behind an air separation plant and a in the oxygen decomposing the oxygen decomposition plant formed Device controllable a gas is introduced into this line, that with respect to the desired conditions the oxygen content and / or the oxygen concentration and / or the amount of oxygen delivered by the gas stream (oxygen mass flow) identifies.

Due to this inventive measure makes it possible to continue to provide in the partial load range shutdown of burner levels in the active burner planes which there _x low-carbon for a stable NO combustion oxygen necessary amounts and concentrations available in other places where the oxygen-containing gas stream only Cooling serves, however, to reduce the oxygen content and the oxygen concentration to such an extent that considered overall over the entire firebox such a procedural equilibrium is set that in the steam generator leaving the flue gas and the CO ₂ capture supplied flue gas is no longer detectable as impurity detectable or measurable or evaluated O ₂ content.

There this problem arises in particular when switched off Burner this continues to be charged for the purpose of cooling with gas streams have to be, the invention provides in an embodiment, that at least part of the part load of the steam generator, in particular for the purpose of cooling, with an oxygen-containing gas stream applied burner or nozzle levels and / or burner or nozzles such a supply means and / or a having such supply line.

ever After use, it is possible for cooling of burners the secondary gas and / or tertiary gas streams each burner individually, separately and independently or at least per burner level with the then necessary, but be supplied with minimal required oxygen. The invention therefore provides in an embodiment that the secondary and / or Tertiary gas supply to each burner level and / or each Burner individually and / or separately from other gas streams be acted upon by oxygen and / or individually and / or separately from other gas streams in terms of their oxygen content is adjustable.

As well It is possible that the core air streams or core gas streams be used for cooling. For this possible is, the invention is further characterized by the fact that the Core gas supply of each burner level and / or each burner individually and / or separately from other gas streams with oxygen acted upon and / or individually and / or separately with respect its oxygen content is adjustable.

As usual the fuel for a burner level of a mill supplied by means of a conveying gas flow, It may also be provided that when switching off this burner level, through the corresponding conveyor cross section exclusively an oxygen-containing gas stream is conveyed. The invention therefore also provides that the primary gas supply every Burner level and / or each burner individually and / or separately from Other gas streams can be acted upon with oxygen and / or individually and / or separately with regard to their oxygen content is adjustable.

there it is also appropriate, the Oxygenregulierungsmöglichkeit also for the upper air supply and / or the supply provided by sidewall nozzles. Another embodiment of Invention therefore consists in that the upper air nozzle supply and / or the sidewall nozzle supply to each nozzle plane and / or each nozzle individually and / or separately from others Gas flows can be acted upon by oxygen and / or individually and / or separately adjustable with respect to their oxygen content is.

Around a particularly large variation of the Setting distribution of different combustion and / or To achieve oxidizing oxygen-promoting gas streams, it is then according to another embodiment of the invention advantageous if all gas flows at each burner level and / or each Burner and / or each nozzle level and / or each nozzle individually and / or separately from other gas streams Oxygen acted upon and / or individually and / or separately are adjustable in terms of their oxygen content.

The separate and individual adjustment of the gas flows and the impingement of the individual burner or burner levels or nozzles or nozzle levels can be constructive particularly favorable realize that each burner or nozzle plane and / or each burner or each nozzle with an oxygen-containing gas stream feeding Supply line is connected, the oxygen content of the respective supplied gas stream independently from the other burner or nozzle levels and / or others Burners and / or other nozzles respectively supplied Gas flows is adjustable.

by virtue of the inventive design of a steam generator It is possible in the individual burners or burner levels or nozzles or nozzle levels, the oxygen content in the respective gas stream between 0 and 100 wt .-% or Vol .-% in particular less than 21% by volume, thereby obtaining the invention also distinguished.

An embodiment of the steam generator according to the invention then further consists in that in the supply line, a mixture of recycled CO ₂ -containing flue gas and mixed oxygen of the respective burner or nozzle level and / or the respective burner or the respective nozzle is supplied.

Since the inventive design of a steam generator is sensible and advantageous in particular when a CO ₂ separation from the resulting flue gas is to be carried out in a steam generator operated in oxyfuel operation, the invention finally also characterized by the fact that the steam generator at least temporarily operated in the oxyfuel process.

If cooling gas is also applied to the primary pipe in the partial load range, it must also be provided with oxygen for this gas stream individually or levelwise or the primary gas feed is to be provided with a flap, with the gas from another gas stream (secondary air, tertiary air or others) ) can be deflected to the primary gas cross-section. Such a construction is for the air operation of the EP 1 369 640 B1 known. Are upper air and side wall nozzles available, and these are applied in part-load operation with cooling gas, so these gas streams are also individually or level to provide their own admission and control with oxygen.

Overall, the invention thus provides that at least the secondary gas, Tertiärgas- and core air streams, as far as they are also provided for cooling the respective burner, each burner individually or at least level by level supplied with the necessary oxygen, so in the partial load range of the steam generator, the oxygen content of this Gas flows to a lower than the full load and normal load case lower value, in extreme cases down to zero, can be reduced. The installation of the necessary Kanal Zuführmittel- and / or supply line system is not considered in the interpretation of fossil fuel fired large steam generators of power plants. However, if a total surplus of oxygen to be complied with should not be exceeded in the oxyfuel operation of such a large steam generator at partial load, this is a relatively simple measure to avoid oxygen contamination in the exhaust gas which would be detrimental to the CO ₂ separation.

The invention is explained in more detail below by way of example with reference to a drawing. This shows in the single figure in schematic representation a four burner 1 comprehensive burner level of a fossil-fueled combustion chamber of a steam generator. The burners 1 stand over one in sub-lines 2a - 2d branching supply line 2 each with a coal mill 3 in line connection. In the design of the system shown in the figure, in particular the firing system for a oxyfuel operation of the steam generator, the coal mill 3 over a line 4 CO ₂ -containing recirculated flue gas supplied via the line 2 also the burners 1 reached. The over the supply line 4 supplied gas stream then promotes those in the mill 3 ground coal via the feed line 2 and the branches 2a - 2d this primary gas and coal dust the respective burners 1 to. In partial load operation of the steam generator, it is possible to turn off the primary gas or carrier gas / coal supply to the individual burners, in particular to all burners of the illustrated level, and so the burner 1 to take out of service. For adjusting the oxygen content in the through the supply line 4 supplied, recirculated flue gas stream is a supply line shown in dashed lines 5 provided with an oxygen heater 6 in line connection, which is from an air separation plant 7 over a line 8th an oxygen gas stream is supplied.

For individual and separate supply of the further provided in the burners gas flow cross sections with core "air", secondary "air" and tertiary "air", wherein the term "air" essentially nitrogen-free, oxygen-containing gas flows, these are at each burner 1 connected to its own supply line. So will the burners 1 over the supply lines 9a - 9d Core "air", over the supply lines 10a - 10d Secondarily "air" and over the lines 11a - 11d Tertiary "air" supplied. The supply of a substantially nitrogen-free, oxygen-containing gas stream to nozzles 13 , For example, upper "air" gas nozzles, a nozzle plane via the lines 12a - 12d , The oxygen warmer 6 is also operatively connected to delivery means 9 . 10 . 11 and 12 , in cooperation with the respective associated supply lines 9a - 9d . 10a - 10d . 11a - 11d and 12a - 12d ensure that each of the feed lines can be exposed to oxygen individually and / or separately from the other gas streams, wherein the oxygen content of the respective gas stream conveyed therein and the oxygen concentration of this gas stream and the oxygen mass flow conveyed with the gas stream can be selectively adjusted, so that the the firing required oxygen-containing Gastrom to the (gas) nozzles 13 and / or optionally with a cooling by the burner in the respective 1 Guided oxygen-containing gas stream regulated and adjustable and the total introduced into the combustion chamber oxygen or excess oxygen does not exceed the particular desired level. The delivery means 9 . 10 . 11 and 12 also include the possibility of supplying and admixing recycled, CO ₂ -containing flue gas and the possibility of measuring and controlling the respective oxygen concentration in the individual streams in the supply lines 9a - 9d . 10a - 10d . 11a - 11d and 12a - 12d , so in the feed lines 9a - 9d . 10a - 10d . 11a - 11d and 12a - 12d the oxyfuel operation characterizing oxygen-flue gas mixtures the burners 1 and / or the nozzles 13 can be supplied. In particular, the so-called air ratio is thereby selectively adjustable and adaptable to the respective load case.

By this configuration can be avoided not only in the partial load range by the individually adjustable O ₂ - or oxygen levels unwanted O ₂ - or oxygen levels in the flue gas, even in full load operation can thereby ge wanted to set oxygen ratios targeted.

So can in full load operation the different burner cross sections of a Brenners or the burner of a burner level each a different or at least the respectively desired admission with be fed to an oxygen concentration, so that thereby a flame image or temperature image or a combustion adjusted analogously to the usual air operation (non-oxyfuel operation) can be. Likewise it is possible a trim in Referring to the oxygen content / oxygen concentration between To adjust burner levels.

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• EP 1369640 B1 [0021]

Claims (11)

Steam generator with fossil-fired combustion chamber and at least one burner level and / or at least one top air nozzles and / or side wall nozzles having plane with connected feeding means ( 9 . 10 . 11 . 12 ) and / or supply lines ( 2 . 4 . 5 . 9a - 9d . 10a - 10d . 11a - 11d . 12a - 12d ) by / by means of which (r) combustion gas and / or oxidation oxygen-promoting gas streams can be fed to the combustion chamber, characterized in that the supply means ( 9 . 10 . 11 . 12 ) and / or the supply lines ( 2 . 2a - 2d . 4 . 5 . 9a - 9d . 10a - 10d . 11a - 11d . 12a - 12d ) are formed such that at least a part of each of a burner or nozzle plane and / or in each case a burner ( 1 ) or a nozzle ( 13 ) supplied individually and / or separately from the other gas streams can be acted upon by oxygen and / or individually and / or separately from the other gas streams with respect to their oxygen content or their oxygen concentration and / or the oxygen mass flow promoted with them adjustable. Steam generator according to claim 1, characterized in that at least part of the part load of the steam generator, in particular for the purpose of cooling, acted upon by an oxygen-containing gas stream burner or nozzle level and / or burner ( 1 ) or nozzles ( 13 ) such a delivery means ( 9 . 10 . 11 . 12 ) and / or such a supply line ( 2 . 2a - 2d . 9a - 9d . 10a - 10d . 11a - 11d . 12a - 12d ) having. Steam generator according to claim 1 or 2, characterized in that the secondary and / or Tertiärgasversorgung each burner level and / or each burner ( 1 ) is individually and / or separately acted upon by other gas streams with oxygen and / or individually and / or separately adjustable in terms of their oxygen content. Steam generator according to one of the preceding claims, characterized in that the core gas supply of each burner level and / or each burner ( 1 ) is individually and / or separately acted upon by other gas streams with oxygen and / or individually and / or separately adjustable in terms of their oxygen content. Steam generator according to one of the preceding claims, characterized in that the primary gas supply to each burner level and / or each burner ( 1 ) is individually and / or separately acted upon by other gas streams with oxygen and / or individually and / or separately adjustable in terms of their oxygen content. Steam generator according to one of the preceding claims, characterized in that the upper air nozzle supply and / or the sidewall nozzle supply to each nozzle plane and / or each nozzle ( 13 ) is individually and / or separately acted upon by other gas streams with oxygen and / or individually and / or separately adjustable in terms of their oxygen content. Steam generator according to one of the preceding claims, characterized in that all gas flows of each burner level and / or each burner ( 1 ) and each nozzle plane and / or nozzle ( 13 ) are individually and / or separately acted upon by other gas streams with oxygen and / or individually and / or separately adjustable in terms of their oxygen content. Steam generator according to one of the preceding claims, characterized in that each burner or nozzle plane and / or each burner ( 1 ) or each nozzle ( 13 ) with an oxygen-containing gas flow supplying supply line ( 2 . 2a - 2d . 4 . 5 . 9a - 9d . 10a - 10d . 11a - 11d . 12a - 12d ), wherein the oxygen content of the respectively supplied therein gas stream is independent of the other burner or nozzle planes and / or other burners and / or nozzles respectively supplied gas streams adjustable. Steam generator according to one of the preceding claims, characterized in that the oxygen content in the respective Gas flow between 0 and 100 wt .-% or Vol .-%, in particular less than 21 Vol .-% is adjustable. Steam generator according to one of the preceding claims, characterized in that at least in a part of the supply lines ( 2 . 2a - 2d . 4 . 5 . 9a - 9d . 10a - 10d . 11a - 11d . 12a - 12d ) a mixture of recycled CO ₂ -containing flue gas and mixed oxygen of the respective burner or nozzle level and / or the respective burner ( 1 ) or the respective nozzle ( 13 ) is supplied. Steam generator according to one of the preceding claims, characterized in that the steam generator at least temporarily operated in oxyfuel mode.