DD160979A3 - METHOD FOR THE AUXILIARY ARMING OF A CARBON STEAM GENERATOR - Google Patents

Abstract

The invention relates to a method for zuendoel- or gas-poor startup of a pulverized coal-fired steam generator with a fixed evaporation end point, being closed when starting the Kesselkopfschieber or the high-pressure side Umleitstation and Zuendoelbrenner or gas burner in operation. In order to reduce the operating time of the Zuendbrenner when starting and thus save Zuendbrennstoff, it should be largely retained by the operation of Zuendfeuerung in the steam generator heat in the water-steam system and the pulverized coal firing only in dependence on the achievement of firing parameters are put into operation. According to the invention, depending on the heat state of the steam generator such a number of ignition burners staggered put into operation that the permissible pressure or temperature change rate of the critical component is maximized, the Stattwasserablaesse and Entwaesserungen only for technologically related removal of a minimum water and Dampfmaenge from the evaporation system be opened, so that the supplied with the Zuendfeuerung heat is used primarily to increase the pressure in the water-steam system, and that the Kesselkopfschieber or the high-pressure side Umleitstation anfueckt and ascended with staggered in a conventional manner commissioning the pulverized coal firing at almost the same system pressure is, so that primarily by the increased heat input in the combustion chamber, a rapid development of steam volume in the water-steam system is achieved and that the Zuendbrenner staggered taken out of service and the kick-off or. Coupling parameters can only be approached with the dust firing.

Description

Method for the low-ignition start-up of a pulverized coal-fired steam generator

Field of application of the invention

The invention relates to a method for low-ignition start of pulverized coal natural or forced circulation steam generators and forced flow steam generators with fixed evaporation end point, and with or without superimposed circulation, which are approached with a Zündöl- or Zündgasfeuerung and ampfst ig with ümleitstat ions and equipped with or without Kesselkopfschieber are.

Characteristic of the known technical solutions

In order to achieve the required temperature for the ignition of the pulverized coal-air mixture in the combustion chamber of the steam generator, the start-up operation of the pulverized coal-fired steam generator with a Zündöl- or -gasfeuerung is required. Depending on the heat state of the steam generator and the quality of the coal dust, an ignition oil requirement of up to 50 t per start-up cycle is necessary for a large steam generator.

For the purpose of Zündöleinsparung it is known to make a preheating of the steam generator flue gas and / or water side.

In order to save ignition oil, it is also known to introduce specially prepared flammable pulverized coal via the pilot burner system or a separate pilot burner into the combustion chamber and after ignition of this pulverized coal the

to achieve the required combustion chamber temperature. Furthermore, it is known that the pulverized coal-air mixture Tor burn the burner main in the startup phase thermally and / or to create an annealing bed. It is also known to keep out of service steam generator flue gas and / or water side warm. All mentioned steam generator s is in common that the solid Yerdampfungsendpunkt forming thick-walled component, for. 3. the boiler drum or bottle, at the same time the critical component with the lowest permissible rate of change of temperature and thus determines the approach speed of the steam generator »In practice, a constant amount of heat is introduced into the combustion chamber of the steam generator and known at a constant with the aid of oil or Gaszundfeuerung Feed water quantity, the pressure development of the Yerdampfers ^ stems by opening the Kesselkopfsschiebers and / or the UmIeitstat ions, the drainage and / or the saturated water drainage or the Trommelschnellablasses influenced and adapted to the permissible rates of change of the critical component. As a result, a large part of the heat supplied in the combustion chamber with the boiling water or hoohkalorisohen steam is dissipated again, which has unnecessary heat loss and increased oil or gas use result.

When starting the steam generator from a still existing pressure and thus temperature level, z. As in the warm start, the permissible rate of change is not exhausted, thereby delaying the pressure development of the Yerdampfersystems and the temperature development of the superheater? St ems. The latter, in turn, causes a late closing of the drainage, which additionally reduces the Drucikaufbau. In addition, the after-ignition evaporation causes the superheaters, collectors, and pipelines to flow with L-colder steam, which is associated with a drop in temperature, especially in the exhaust collectors and piping. If then the dust firing is switched on after reaching the ignition conditions, are due

the rapidly increasing vapor evolution exceeded the permissible pressure and temperature change rates. To avoid this, in the known start-up technologies, the connection of the dust firing and the achievement of certain parameters of the water-steam system, eg. As pressure, temperature, mass flow, Teraturaturdifferenzen, and degrees of opening of Umleitstationen made dependent. This makes it necessary to keep the oil or Gaszündfeuerung longer in operation, as it would be necessary due to the already reached flue gas side ignition conditions, eg. B. after reaching a certain Brennkamraertemperatur or temperature of a suitable location of the flue.

Object of the invention

The aim of the invention is to save on startup by shortening the operating time of Zündöl- or gas burner Zündöl or gas.

Explanation of the essence of the invention

The invention has for its object to keep the heat introduced by the operation of Zündfeuerung in the steam generator largely in the water-steam system and to take the pulverized coal firing only in response to achieving firing parameters in operation.

This is achieved by the fact that according to the invention irf depending on the heat state of the steam generator staggered such a number of pilot burners is taken in 3betrieb that the allowable rate of change is maximized, the Sattwasserablässe and drains only for technologically related discharge of a minimum water and Darapfraenge from the Evaporating system can be opened so that the heat supplied with the ignition heat is used primarily to increase the pressure in the water-steam system, and that the boiler head slide or the high-pressure side Umleitstation moved and staggered with the manner known per se

Commissioning the pulverized coal firing is raised at approximately the same system pressure, so that primarily by the increased heat input in the combustion chamber, a rapid Darapfmengenentwicklung in water-steam Systera is achieved and that the pilot burner staggered taken out of service and the Anstoßbzw. Coupling parameters can only be approached with the dust firing.

embodiment

In one embodiment, the invention is explained in detail. The drawing shows:

Fig. 1: Drift change rate as a function of the pressure at the end of the dilution point at a saturated steam temperature increase of 2 k / min and 3 k / min;

Fig. 2: theoretical pressure development as a function of time at a saturated steam temperature increase of 2 k / min and 3 k / min;

3 shows the basic start-up circuit of a once-through steam generator with superimposed circulation without boiler head slider and diverter stations,

Fig. 4: the basic start-up circuit of a natural circulation Darapferzeugers with Kesselkopfschieber and without reheater; sowis

Table ·: Comparison of starting technologies,

The permissible rate of change of temperature resulting from the strength calculation for the critical component gives, according to the state equations for water and steam, the variable pressure change rate which is variable as a function of the system pressure (FIG. 1). From the permissible pressure change rate, the theoretically possible pressure development of a vaporizer as a function of time can be determined (FIG. 2). In the start-up circuit for _a once-through steam generator with superimposed circulation (FIG. 3), the steam generator is fed via feedwater line 1 and feedwater control valve 2. The feed water passes via the line 3 in the economizer 4 and after its preheating via the line 5 to

mixing point

6, where it mixes with the coming via the line 7 from the Separatur 8 saturated water. About the Umwälzpumpensaugleitung 9, the circulation pump 10 and the circulation pump pressure line 11, the mixed water is supplied to the evaporator 12, in which a part "evaporated, and via the Dampfabführröhre 13, the generated steam-water Gemisoh tangentially into the separator 8. The lower part of the evaporator 12 designed as Wandberohrung is located in a combustion chamber 14, in which open the Zündölbrenner 15 and the pulverized coal burner 16. In the separator 8, the incoming water-steam mixture is separated, the saturated water flows down to the line 7 and to maintain the Water level in the separator via the saturated water line 17 and the Hegelorgan 18 excess saturated water is discharged .. The dry saturated steam passes through a steam outlet line 19 in the first superheater 20, which are arranged as a wall or ÜBerührüberhitzer in the following unheated collectors and / or mixing tubes 21st are drains 22 a bound, is discharged through the forming condensate. The steam then flows over the formed as a radiation super heater middle superheater stages 23, collectors and mixing tubes 24, which are also drains 25, the final superheater 26, then into the main steam line 27 and since he to ܬchdruckseitigen ümleitstation 28, gate of the other drains 29 are involved , Via the cold rail 30, the expanded steam passes to the first reheater stage 31, via collector and mixing tubes 32, where the reheater drainage 33 is arranged, to the second reheater stage 34 and then via the hot rail 35 to the low pressure side Umleitstation 36. Via line 37 finally flows twice relaxed steam to the condenser 38, in which it condenses.

The explanation of the invention for a forced once-through steam generator with superimposed circulation (Fig. 3) takes place using the example of the warm-start (warm start) for a 815 t / h. Steam generator. A warm start should be understood to mean the startup of a steam generator after a standstill - 8 hours, with the residual pressure in the evaporator system falling short of

at least 10 kp / cm. A comparison of the method according to the invention with the start-up procedure (FIG. 5) as a function of fixed time sequences and specific tests (indicator T) clarifies the different steps of the handling (identification S ,, S, etc.). Before starting, the ümleltstat ions are 28; 36, the drainages 22; 25; 29; 33 and the saturated water control valve

18 closed. First, by strand-opening the drainages 22; 25 ensures that condensate formed in the cooling phase is derived from the Überleit system · The circulation pumps 10 are turned on and the feedwater control valve 2 is set a minimum amount of feed water and at constant water level; discharged in separator 8, the same amount of saturated water via line 17 and control valve 18. At the time of ignition of the first two oil burners 15, only the drainages 22 are open after the first superheater stages 20 located in the region of low flue gas heat output. The forming steam flows over the pipe

19 and the superheater stages 20 to the drainages 22, where a small part is discharged, while the majority contributes to the pressure increase in the water-steam Syst em. The start-up of further oil burners 15 depends on whether the rate of pressure change that occurs in the critical component 8 is less than the permissible value (FIG. 2). Is z. For example, if the system pressure before ignition of the oil burners is 10 kp / cm, ie the lowest value for warm start, and the permissible saturated steam temperature increase is 2 k / min, then a rate of pressure change of 0.4 at / min is permissible (FIG 5 minutes after the ignition of the first oil burner, a pressure of -12 kp / cm ^ would have to be reached (40 to 45 minutes of the time counting). If this is not the case, then another oil burner 15 is to be put into operation. At a system pressure of 12 kp / cm, the permissible pressure change rate is already just under 0.5 at / min (FIG. 1), and 10 min after the start of ignition (50 min) at least 15 kp / cm would have to be reached (FIG. 2). Tom reaching this pressure, the connection of the fourth oil burner 15 is dependent, etc. Has the Strangtemperatür after the first superheater 20 reaches a value that

20_Jüber the saturation temperature is ,, the drainages 25 are opened and the drainages 22 closed. The now already superheated steam continues to flow through mixing tubes and collectors 21 to the middle, lying in the field of radiant heat transfer superheater stages 23, which are therefore already well warmed up. Sin small part of the steam is discharged through the drainages 25, the predominant already superheated steam ensures further rapid pressure increase. The criterion high temperature higher saturation temperature + 2Ok is quickly reached for the average superheater stages, and the drains 29 can be opened and the drains 25 closed. Thus, mixing tubes and collectors 24, the final superheater stage 26, the live steam outlet collector and the main steam line 27 are flown. Since a high pressure and temperature level has already been reached, temperature drops in the unheated thick-walled components are avoided. Meanwhile, the flue gas temperatures in the combustion chamber 14 have risen so high that the conditions for switching the first mill 16 are met. Already before are the UmIeitstat ions 28; 36 to encourage their warming and the flow of the Zwischendampfsyst ems 30 bis

35 to secure, with the drainage 33 is opened and the drainage 29 is closed. Immediately before putting the first mill 16 into operation, the diverting stations 28;

36 moved into the control range and maintained the pressure in the system from the setpoint constant. Hun is the staggered commissioning "of 4 mills 16 and the staggered decommissioning of the oil burner 15 with the exception of two oil burners of the lower floor.Further increase the fuel and feed water quantity ensures rapid steam development and to achieve a stable fire situation, these oil burners except The starting or coupling parameters are only started with the dust firing system.

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The explanation of the invention for a natural circulation steam generator with Kesselkopfschieber and without superimposed circulation takes place in a general example (Fig. 4):

The steam generator is fed via the feedwater line 1 and the feedwater control valve 2. Via the line 3 ', it flows to the economizer 4, where it is preheated and then fed to the water space of the drum 5, is. The resulting wet steam flows through the line 8 due to natural drive to the drum 5. The deposited in the drum 5 dry saturated steam is the Dampfabführrohre 9 the ÜberhitzerniO; 11 supplied. When the boiler head slider 12 is closed, the heat supplied in the combustion chamber 13 with the aid of the ignition firing 14 until the connection of the pulverized coal firing 15 to the pressure build-up in the water-steam system 3 to

11 used. About the drain and / or the Trommelschnellablaß 16 and the drains 17 only minimum amounts of saturated water or steam are removed. With the commissioning of the dust firing 15 is the Kesselkopfschieber

12 opened in such a way that at approximately constant pressure in the water-steam Syst em 3 to 11 of the steam generated via the main steam line 18 (analogous to FIG. 3) to the UmIeit- and / or Heduzierstationen (not shown) flows *

Although the invention is described exclusively for the starting operation with ignition oil or gas, so the invention is also applicable to the start-up operation with specially treated ignitable coal dust.

The invention achieves the following door parts:

1. By connecting exactly so rieler Ölzündbrenner or, Gaszund burner, that just closed the permissible pressure change rates are used with closed Kesselkopfschieber or closed HD station, depending on rome heat state of the steam generator reduces the number of Zündbrenner used and thus the oil demand when starting ,

The critical component (drum or bottle) is gently approached, and temperature drops in the outlet heaters of the superheater and piping and thus additional stress on these components when moving from the warm state by flowing with colder steam are Yermieden.

The switching on of the dust firing is only dependent on the parameters of firing parameters (combustion chamber temperature), so that the duration of use of the pilot burners is significantly lower

By starting with closed Kesselkopfschieber or Umleitstation only so much feed water is needed that pre-evaporation is avoided in economizer. On the one hand, this prevents a critical feedwater situation during startup due to the limited power of the startup feed pumps. • On the other hand, the startup losses are reduced.

With increasing system pressure, the required evaporation heat is reduced, so that the desired rapid development of steam volume is achieved when connecting the pulverized coal firing. As a result, a sufficient cooling of the immediately after the combustion chamber is arranged and secured in this start-up phase thermally most loaded superheater stage.

The maximum possible pressure increase in the evaporator system in conjunction with the earlier connection of the dust firing leads to a shortening of the startup time.

Claims (2)

1. A method for zündöl- or Zündgasarmen starting a coal dust-fired boiler rait fixed evaporation end point, which is closed when starting the Kesselkopfschieber or the high pressure Uraleitstation, pilot burner are put into operation and the critical component (drum or bottle) after the temperature or pressure change rate is driven, characterized in that in dependence vora heat state of the steam generator such a number of pilot burners is stepped into operation, that the permissible rate of change is maximized, the Sattwasserablässe and drains only for technologically related discharge of a minimum amount of water and steam from the Evaporating system can be opened so that the heat supplied to the ignition firing is used primarily to increase the pressure in the water Datnpf system, and that the boiler head slide or the high-pressure side Umleitstation is is engaged and ascended with the staggered in known-W se _Q ise commissioning of the pulverized coal at approximately the same system pressure, so that a rapid steam development is achieved in the water-steam system by the increased supply of heat in the combustion chamber of priority and that the pilot burner staggered except Operation taken and the Anstoßbzw. Coupling parameters are approached only with the dust firing, 2 «method according to item 1, characterized in that the pulverized coal firing is taken immediately after reaching the ignition temperature in the combustion chamber, regardless of the parameters of the water-steam Systeras in operation. 3. The method according to item 1 and 2, characterized in that the ignition firing is operated with specially treated ignitable coal dust. Hierzo_ji-.Sesten drawings iS-1 Fig. 2 Pressure change rates as a function of the pressure at the evaporation end point at a saturated steam temperature increase of 2 K / min and 3 K / min Δρ / At at / min Theoretical Dryck development as a function of time at a
Sqttdampfemperatursteigerung of 2K / min and 3 K / min kp / cm 3 4 5 6 7 8910 2Ü 40. * .5 6 7 8 910 ν 30 4o 5 © 6ä Warm start 815 t / h steam generator ρ ρ Criterion: 100 kp / cm pressure in the separator 10 kp / cm Step / Time Binding Approach Technology Test (min.) S-] High Pressure Soaking 1 (22) 5 min, "on / off" High pressure drainage 2 (25) 5 min. "On / off" High pressure drainage 1 and 2 on level control in operation Set the feedwater quantity of 27,8 kg / s (100 t / h) per line 2 Ignition oil burner lower; iStage "on" 2 Ignition oil burner lower level "on" 2 Ignition oil burner upper level "on" Line temperature after the average superheater levels (23) 20 K above saturation temperature? Dewatering before live steam slide (2 $) "on" temperature of Sndüberhitzerstufe (26) increases? HD station (28) from end position "to" approach high-pressure drainage too Intermediate steam pressure 10 kp / cm Temperature after ZU Il (34) 100 K above saturation S ₁₁ Advance the ND station (36) from the "too" end position T Toraussetzungen for switching the 1st mill , 6 Ignition oil burners in operation. Steam temperature from 300 to 350 ⁰ C. Intermediate steam temperature 300 - 350 ⁰ C Separator pressure 40 to 50 kp / cm. HD station (28) 10% opening level of ND station (36) 10 % opening degree , Mill in operation , Zündölbrenner ohere floor "off" , Mill in operation , Ignition oil burner upper floor "off" , Mill in operation , Zündölbrenner lower floor "off" , Mill in operation , Ignition oil burner lower level "off" Approaching the initiation or coupling parameters  / 6 " S ^ -i initiate or couple 522 Performance increase of the steam generator 523 3rd and 4th ignition oil burner lower floor "off" Step / time start-up technology according to the invention T est (min.) S-j high pressure drainage 1 (22) 5 min "on / off" 52 high-pressure drainage 2 (25) 5 min "open / close" 53 Water level control in operation Set the feed water quantity of 16.6 kg / s (60 t / h) per line 54 high pressure drainage 1 "on" 55 0 2 Ignition oil burner lower level "on" T 5 'Is the resulting pressure change speed in the critical component smaller than the permissible pressure change speed? 1 Zündölbrenner lower floor "a Sy 1 Zündölbrenner lower floor "one" T .ja strand temperature after the first over ~; heat stages (20) 20 K above saturation temperature? S3 high pressure drainage 2 "on" High pressure drainage 1 "to" T .ja strand temperature after the average superheater stages (23) 20 Z above saturation temperature? Sg drainage gate Frisoh steam knife (29) "on" T .ja temperature after final overheating stage (26) increases? SI ₀ high pressure drainage 2 "to" T. »Yes Δό / δ ΐ - <Γ (/ ifi / jist) -ί-J. ^ S-j ή 1 Ignition oil burner upper floor "on." T & f) tXt <Up ict) -.J- { S-J2 ^ Zündölbrenner upper floor "one" T requirements for switching the 1 mill: Flue gas temperature to Zu I - 350 ⁰ C ο Move to HD station (28) from end position "to" 5 ¹ Move to ND station (36) from end position "to" 10 'Move HD and ND station to control area and Setpoint live steam pressure and intermediate steam pressure constant
S _1. ^ o 1. Mill in operation 5 ₁₇ 1. Ignition oil burner upper floor "off" 5 ₁₈ 10 '2nd mill in operation 5 ₁₉ 2. Ignition oil burner upper floor "off" 5 ₂₀ 2d 3. Mill in operation Sp ₁ 1 · 'Zund81brenner lower floor' off ' 5 ₂ 2 30 '4th mill in operation 5 ₂ 3 - 2. Ignition oil burner lower floor "off" Increase amount of live steam and fuel up to Fire stable T 40'.ja fire stable? 525. 3rd and 4th ignition oil burner lower level "off" Spg Approaching the initiation or coupling parameters 527 'nudging or coupling 528 Performance increase of the steam generator