Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F22—STEAM GENERATION
  • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
  • F22B29/00—Steam boilers of forced-flow type
  • F22B29/06—Steam boilers of forced-flow type of once-through type, i.e. built-up from tubes receiving water at one end and delivering superheated steam at the other end of the tubes
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F22—STEAM GENERATION
  • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
  • F22B29/00—Steam boilers of forced-flow type
  • F22B29/06—Steam boilers of forced-flow type of once-through type, i.e. built-up from tubes receiving water at one end and delivering superheated steam at the other end of the tubes
  • F22B29/061—Construction of tube walls
  • F22B29/062—Construction of tube walls involving vertically-disposed water tubes
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F22—STEAM GENERATION
  • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
  • F22B29/00—Steam boilers of forced-flow type
  • F22B29/06—Steam boilers of forced-flow type of once-through type, i.e. built-up from tubes receiving water at one end and delivering superheated steam at the other end of the tubes
  • F22B29/061—Construction of tube walls
  • F22B29/065—Construction of tube walls involving upper vertically disposed water tubes and lower horizontally- or helically disposed water tubes
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F22—STEAM GENERATION
  • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
  • F22B37/00—Component parts or details of steam boilers
  • F22B37/02—Component parts or details of steam boilers applicable to more than one kind or type of steam boiler
  • F22B37/22—Drums; Headers; Accessories therefor
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F22—STEAM GENERATION
  • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
  • F22B37/00—Component parts or details of steam boilers
  • F22B37/02—Component parts or details of steam boilers applicable to more than one kind or type of steam boiler
  • F22B37/22—Drums; Headers; Accessories therefor
  • F22B37/227—Drums and collectors for mixing

Definitions

• the invention relates to a forced once-through steam generator with a surrounding gas-tight welded, formed in the vertical direction steam generator tubes wall, in which a fürgangs ⁇ collector is arranged within the enclosure, the first plurality of parallel switched steam generator tubes outlet side with a two ⁇ th, the first A plurality of series connected downstream plurality of steam generator tubes connected on the inlet side flow medium side. It further relates to a power plant with such a steam generator.
• a steam generator is a plant for producing steam from a flow medium.
• a flow medium typically water is heated, and vice ⁇ converts into steam.
• the steam is then used to drive machinery or generate electrical energy.
• a steam generator comprises an evaporator for generating the steam and a superheater, in which the steam is heated to the temperature required for the consumer.
• the evaporator is preceded by a preheater for the use of waste heat, which further increases the efficiency of the overall system.
• Steam generators are industrially today usually designed as ⁇ serrohrkessel, ie, the flow medium is guided in steam generator tubes.
• the steam generator tubes can be welded gas-tight with each other and thus form a order ⁇ supervisedswand, within which the heat-supplying hot gas is guided.
• Steam generators can be designed either in a vertical or horizontal design, ie, the hot gas is guided in the vertical or horizontal direction.
• Steam generators can furthermore be designed as forced-circulation steam generators, the passage of the flow medium being forced by a feed pump. The flow medium is conveyed by the feed pump into the boiler and successively the preheater, the evaporator and the superheater are flowed through.
• the tubing of the containment is subdivided into a unte ⁇ ren and an upper section, said lower section includes a first plurality of parallel-connected steam ⁇ generator tubes and the upper portion of a second, the first plurality serially downstream Plural parallel connected steam generator tubes.
• the lower and upper From ⁇ section are connected by a passage collectors.
• the invention proceeds from the consideration that the overheating of individual steam generator tubes is due to a unzurei ⁇ sponding derivative of the incoming heat by flow medium. Inadequate heat removal occurs when the steam generator tube in question has too low a mass flow. With a pronounced natural circulation characteristic, with very low inlet steam content and very low heat input, the hydrostatic pressure drop in these tubes is already approximately as large or equal to the total pressure difference between the inlet and outlet of the steam generator tube. The remaining pressure difference as a driving force of the flow is therefore very low or disappears completely, so that in the worst case the flow stagnates.
• Throughput collector causes a complete pressure equalization, but not complete mixing of the incoming flow medium, which would lead to a balance of water and vapor content in the downstream steam generator tubes. Due to the low vapor content of the lower heated steam boiler tubes of the lower section and additional local segregation phenomena in the Collector can thus still go at entry into individual tubes of the upper vertical bore in certain operating conditions of the vapor content to zero. Thus, this phenomenon should be avoided by a sufficient weakening of the natural circulation characteris- tics.
• the number and / or the inner diameter of the steam generator tubes come as a parameter in the design of the mass flow density of Umfas ⁇ sungswand into consideration. These parameters essentially influence the flow characteristic within the enclosure wall and at the same time can be influenced in the design of the steam generator without any special effort.
• the surrounding wall of a steam generator in a vertical construction can have different horizontal cross sections.
• a particularly simple construction is possible if the cross section is substantially rectangular.
• the steam generator tubes arranged in the corner regions are heated particularly weakly, since they are furthest away from the center of the hot gas duct and at the same time have a particularly small heat input surface.
• the vapor content of individual corner tubes of the lower section of the vertical bore can be reduced to zero.
• an unevenly distributed water-steam mixture enters the intermediate collector. Since the intermediate collector does not cause sufficient mixing here, too, the mass flow in the downstream corner tubes can come to an end and thus the heat dissipation can be insufficient.
• the through-collector can be arranged horizontally all around, d. h., It connects all below or above arranged steam generator tubes of
• the steam generator tubes downstream of the throughput collector are designed such that the average mass flow density in the paral ⁇ lel switched steam generator tubes of Um chargedswand at full load of the steam generator is not less than 1200 kg / m2s.
• the tubing below the passage collector can be designed spiral ⁇ circumferentially. The tubes run around as surrounding the entire enclosure wall. Although this causes a more complex construction and also a smaller number of steam generator tubes in the lower area, but this heating differences in various areas of the enclosure wall are largely compensated. Nevertheless, he was ⁇ known that even with such a construction in the through-collector to random local segregation can occur, the above-described problems of too low a mass flow in the passage collector downstream
• the steam generator tubes connected downstream of the throughput collector are designed such that the average mass current density in the parallel-connected steam generator tubes of the surrounding wall at full load of the steam generator does not un ⁇ ter is 1200 kg / m2s.
• the heat input to the steam generator tubes of the combustion chamber does not occur exclu ⁇ Lich convectively, but a large part of the heat content is introduced by heat radiation in the steam generator tubes.
• the differences in the heating of individual steam generator tubes can be particularly large. Therefore advantageously has
• the forced-circulation steam generator is followed by a steam turbine, for example for generating electricity, downstream of the flow medium.
• a power plant advantageously has such a steam ⁇ generator.
• FIG. 2 shows a graphical representation of the mass flow density and the fluid temperature at the outlet of a comparatively weakly heated corner tube of the once-through steam generator with different mass flow density designs at full load.
• FIG. 1 schematically shows a fossil-fired, vertically bored forced once-through steam generator 1 according to the invention.
• the once-through steam generator 1 comprises an enclosing wall 4 formed from gas-tightly welded steam generator tubes 2.
• the enclosing wall 4 has a substantially rectangular horizontal cross-section 6.
• a combustion chamber 8 is arranged with a number of burners not shown in detail for the combustion of a fossil fuel, which provide the heat supply to the steam generator tubes 4.
• the enclosure wall 4 is divided into an upper portion 10 and ei ⁇ NEN lower portion 12, wherein the portions 10 and 12 are connected to each other via a through-collector 14.
• the tubing in the lower portion 12 is arranged vertically here, but may also be arranged spirally around the Umfas ⁇ sungswand circumferentially.
• the passage collector 14 collects all of the flow medium exiting from the steam generator tubes 2 of the lower section 12 and thus enables a pressure equalization between the parallel connected
• the flow medium from the passage collector 14 is introduced into the steam generator tubes 2 of the upper portion 10, where it is further heated and optionally superheated.
• the superheated steam is going down further overheating in not shown heating surfaces of a steam turbine not shown in a power plant ⁇ fed system.
• the heat generated by the burner is largely absorbed by heat radiation through the steam generator tubes 2.
• the corner tubes 16 of the lower portion 12 is due to their location in the greatest distance to the center of the once-through steam generator 1 and due to the geometri-see arrangement of particularly low heat-treated surface of the heat input so low that from the corner ⁇ tubes 16 of the lower portion 12 in the passage header 14 entering flow medium has a comparatively low vapor content.
• the passage collector 14 now effects a complete pressure equalization, however, no complete mixing of the incoming flow medium. Due to the described low vapor content at the exit from the corner tubes 16 of the lower section 12 as well as additional local segregation phenomena in the passage header 14, the vapor content at the entrance to individual steam generator tubes 2 of the upper section 10 can become very small. Depending on the operating state of the once-through steam generator 1, this can lead to a significant drop in the flow through individual steam generator tubes 2 as far as stagnation given an unfavorable design of the bore of the upper section 10. This in turn can result in insufficient heat removal and inadmissibly high fluid temperatures, so that ultimately the pipe wall assumes inadmissibly high temperatures and is destroyed.
• FIG. 2 shows a graphical representation of the parameters of the flow medium in a corner tube 16 of the upper portion 10 for various designs of mean mass flow density of the upper section 10 at full load, namely at comparatively low heat and for a partial load ⁇ operation of the steam generator 1.
• the left scale shows the Mas ⁇ senstrom Why in the corner pipe 16 in kg / m2s
• in the right scale shows the fluid temperature at the outlet of Eckrohres 16 in degrees Celsius (° C), in each case plotted against the vapor portion of the flow medium at the pipe inlet.
• Curve 20 shows the mass flow density in the corner tube 16 in a design of the tubing for a mean mass flow density at full load of 870 kg / m2s.
• the drop of the curve 20 to the left of the graph clearly shows how towards lower steam files the mass flow density in the corner tube 16 decreases.
• the mass flow density drops to a value of 40 kg / m2s, which practically equates to a stagnation of the flow in the pipe.
• a sufficient heat dissipation in the pipe is no longer guaranteed and accordingly increases the temperature of the flow medium and thus of the corner tube 16 from a Dampfan ⁇ part of about 0.2 significantly, as curve 22 represents.

Landscapes

• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)
• Control Of Steam Boilers And Waste-Gas Boilers (AREA)
• Engine Equipment That Uses Special Cycles (AREA)

Priority Applications (6)

Applications Claiming Priority (2)

Publications (2)

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Family Applications (1)

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Family Cites Families (12)

• 2010
  • 2010-08-04 DE DE102010038885.8A patent/DE102010038885B4/de not_active Revoked
• 2011
  • 2011-06-16 EP EP11725744.4A patent/EP2601442A2/de not_active Withdrawn
  • 2011-06-16 CN CN201180038297.5A patent/CN103052848B/zh not_active Expired - Fee Related
  • 2011-06-16 WO PCT/EP2011/059989 patent/WO2012016750A2/de active Application Filing
  • 2011-06-16 KR KR1020137002784A patent/KR20130098993A/ko not_active Application Discontinuation
  • 2011-06-16 JP JP2013522156A patent/JP5709995B2/ja active Active
  • 2011-06-16 AU AU2011287836A patent/AU2011287836B2/en not_active Ceased
• 2013
  • 2013-01-22 ZA ZA2013/00582A patent/ZA201300582B/en unknown

Non-Patent Citations (1)

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