Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23H—GRATES; CLEANING OR RAKING GRATES
  • F23H3/00—Grates with hollow bars
  • F23H3/02—Grates with hollow bars internally cooled
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23H—GRATES; CLEANING OR RAKING GRATES
  • F23H2900/00—Special features of combustion grates
  • F23H2900/03021—Liquid cooled grates
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T137/00—Fluid handling
  • Y10T137/8593—Systems
  • Y10T137/85954—Closed circulating system
  • Y10T137/85962—With thermal circulating means [thermo-siphons]

Definitions

• the invention relates to a furnace with liquid-cooled grate elements, each having an inlet and a return for a coolant.
• Such liquid-cooled, in particular water-cooled, grate elements for firing grates have long been known from WO 96/29544 A1 and DE-PS 624 892.
• the arrangement of a container open to the atmosphere is known, but only allows a connection of the return to the atmosphere.
• the flow is, however, charged via a feed pump, whereby the pressure of the coolant in this area, as well as the flow rate, by the work of this feed pump and the downstream of this pump control valves is determined.
• the second document discloses a furnace grate in which a container open to the atmosphere is provided at the upper end, but this container does not serve as a condensation device, but allows the escape of low-pressure steam into the atmosphere.
• the degree of cooling of the cooling medium in this combustion grate is more or less random, since one can not vary the volume flow of the primary air, which serves as a re-cooling medium for the cooling liquid.
• the primary air supplied must orientate itself on the combustion process on the grate and can thus under no circumstances bring about a defined condensation of optionally formed water vapor in the circulating system.
• a disadvantage of modern combustion plants is the fact that a relatively large, regulatory effort must be operated to ensure on the one hand sufficient cooling of the grate elements and on the other hand, the necessary safety with excessive heat on the grate elements.
• the object of the invention is to provide a firing system with a cooling system for the grate elements, which manages for the circulation of the coolant without control device and without conveyor and in which on top of that no facilities for maintaining the safety in terms of pressure are necessary.
• a particularly preferred embodiment which serves in particular the operational safety, is characterized in that the upper, connected to the central manifold end of the shorter leg is by a selected safety height measure below the lowest point of the coolant flow of the deepest grate element.
• the condensation device open to the atmosphere, that even with complete evaporation of the coolant in the circulation cooling system, no higher pressure may arise than that specified by the liquid level of the longer leg of the liquid template, which is arbitrary.
• the liquid level of the longer leg of the liquid template which is arbitrary.
• the distance between the lowest flow level of the deepest grate element and the upper end of the shorter leg connected to the central manifold is referred to as a safety height measure and indicates the liquid level which creates a pressure in the U-shaped liquid reservoir which is intended to counteract a reverse flow in the cooling system.
• this safety height dimension is chosen so that it corresponds to twice the height difference of a tilted grate between the highest and the lowest point of the coolant flow in this Feuerungsrost.
• the central manifold below the flow parallel connected grate elements of the grate steps and in the longitudinal direction of the grate with a the length of the entire furnace grate is arranged at the same height distance which is smaller than the safety height dimension.
• the return has a central collector for the individual flow-parallel grate elements of the grate steps, which is arranged below the grate elements and in the longitudinal direction of the grate with a uniform height over the entire length of the grate, the lower than the safety height measurement is.
• the arrangement of both the central distributor and the central collector with a height distance to the firing grate, which is less than the safety height dimension, is provided because operational changes may make it necessary to change the safety height dimension. Even in such a case, it should be ensured that the central collector and the central distributor have a smaller height distance to the firing grate than corresponds to the safety height dimension.
• This central collector and central distributor are permanently installed and can hardly be changed in height subsequently, which is not valid for the connection to the shorter leg of the U-shaped coolant reservoir, which determines the safety height distance, not to that extent.
• the invention provides in a further advantageous embodiment that the second short leg of the U-shaped coolant reservoir an additional Storage volume for coolant has.
• a preferred embodiment for realizing a liquid reservoir according to the invention is characterized in that the short leg of the U-shaped coolant reservoir is formed as a container into which the longer, thinner in diameter thigh dives and extends to near the bottom of the short leg, that the upper closed End until just below the lowest point of the lowest coolant flow of the deepest grate element extends and that a branch to the central distributor below the highest point of the container goes off.
• the cylindrical container is higher than corresponds to the geodetic height of the short leg, ie the cylindrical container extends beyond the branch to the central distributor.
• the central collector In order to return the entire cooling liquid present in the cooling system again, in a further development of the invention, the central collector, starting from its lowest point, is connected via a line to a condensate collecting vessel. From here, the cooling liquid can be reintroduced into the system by connecting the condensate collecting tank to the condensing device via a pump and a pipe. It is particularly expedient that the line opens according to the invention with a spray nozzle in the condensation device.
• the condensation tank is provided with a cooling device, then the condensed cooling medium can be recycled in cooled form into the condensation device.
• the condensation device is formed as a surface capacitor with water-cooled heat sinks and a switchable wet condensation device in the invention.
• the switchable wet condensation device is formed by the spray nozzle through which cooled condensate is sprayed from the condensate collection tank. This wet condensing device, in which condenses the vapor returned to the condensing device to the cooled water droplets, in some way, the cooling liquid circuit even then sure if the water-cooled tubes of the condensation device should be subject to interference.
• the condensation device can be shut off against the atmosphere and connected to a vacuum source, then the cooling system of the furnace can be put into operation in a particularly simple manner.
• the same negative pressure in the central collector is generated by the pressure reduction in the vapor space of the condensation device, whereby the coolant flows according to the pressure drop from the grate elements to the central collector, this flow start is still supported by so-called start-burners are ignited in the firing space above the grate, which cause a heat radiation on the firing grate.
• start-burners are ignited in the firing space above the grate, which cause a heat radiation on the firing grate.
• the cooling medium located in the grate elements is heated and possibly even evaporated, causing the cooling system in motion in the manner of a gravity heater.
• a Feuerungsrost 2 is arranged, the five successive, constructed of adjacent grate elements, rust stages 2.1, 2.2, 2.3, 2.4 and 2.5, which overlap roof tiles and are inclined so that the rear end of the Feuerungsrostes, where a discharge roller 3 is arranged, is lower than the feed point 4 for the fuel.
• the individual grate stages 2.1 to 2.5 are water-cooled.
• these individual grate stages are connected to a central distributor 5 serving as an inlet via supply lines 6 to 10.
• Cooling liquid usually water
• Cooling liquid is supplied to the individual grate stages via these lines, whereupon the reflux takes place via discharge lines 11 to 15, which each have a throttle 16 to 20 in order to pressurize the system in the central distributor 5 and the individual grate elements to be cooled build.
• the drain lines 11 to 15 open into a central collector 21 serving as a return, from which a line 22 leads to a condensation device 23.
• the condensate accumulating in the condensation device 23 flows via an inlet 24 to a coolant reservoir designated 25, which is designed as a U-tube, of which the longer leg is denoted by 26 and the shorter leg by 27, which serves as a liquid reservoir and a substantial larger diameter than the longer, thinner in diameter, legs 26, which dips into these simultaneously serving as a reservoir for storage liquid shorter leg and thereby extends to just above the bottom 28.
• a connecting line 29 to the central manifold 5 forms the upper end of the shorter leg 27 of this U-shaped coolant reservoir 25.
• the shorter leg which also forms a container 27, extended beyond the junction of the connecting line 29 upwards. This part of the container 27 is designated 30.
• Both the central distributor 5 and the central collector 21 are arranged below the Feuerungsrostes 2 and have the same inclination as the Feuerungsrost, so that the respective grate elements are subjected to the same pressure.
• a condensate line 31 which leads to a condensate collecting tank 32, which is equipped at its lower end with a cooling device 33.
• the condensate is pumped by means of a pump 34 via a line 35 to the condensation device 23, where it is sprayed via a spray nozzle 36 into the condensation device 23.
• the cooling tubes through which the cooling medium flows are indicated schematically in the condensation device, the inlet of which is designated 38 and the outlet 39.
• the cooling system ie the individual grate elements of the central distributor 5 through which the coolant flows, the cooling liquid reservoir 25 and the condensation device 23 are filled up to slightly beyond the connecting line 24.
• the condensation device 23 which is open during normal operation to the atmosphere, briefly closed and connected via a line 40 to a vacuum source.
• the upper, not filled with liquid vapor space 23.1 is under a certain negative pressure.
• the firing grate and thus the coolant present in the grate elements heat is supplied until at a temperature of 96.72 ° C, the transition from the liquid to the saturated steam phase takes place when the cooling system is filled with water.
• the coolant begins to evaporate and the resulting saturated steam is passed via the central collector 21 and the connecting line 22 to the condensation device 23, which is then already in open communication with the atmosphere.
• the saturated steam condenses on the cooling tubes 37. Due to the density difference between the liquid in the coolant reservoir 25 and the saturated steam in the central collector and the vapor space 23.1 of the condensation device 23, the coolant is circulated.
• the condensate collected in the condensate collecting tank 32 from the central collector 21 is cooled by the cooling device 33 and sprayed by means of the pump 34 via the line 35 into the vapor space 23.1 of the condensation device 23.
• This injection of cooled condensate acts as a mixed condensation in which the vapor condenses on the cold condensate droplets, which can thus be switched on for surface condensation.
• the coolant reservoir 25 is sized to have a longer and shorter leg of a U-tube, with the distance of the uppermost point of the longer leg formed by the fluid level in the condenser 23 above the lowest point of the coolant flow of the deepest Grate element 2.5, 4.85 m, so as not to give rise to a higher pressure in the system than 0.5 bar, otherwise the system would fall under the steam boiler regulation and then would be expensive again in their structure.
• the height difference between the lowest point of the coolant flow in the deepest grate element 2.5 to the upper end of the shorter leg, which is formed by the connecting line 29, corresponds to a safety height dimension, which is preferably selected so that it is about twice the height difference between the highest coolant flow point of the uppermost grate element and the lowest coolant flow point of the lowest grate element corresponds.
• This safety height measurement results in a water column and thus a certain pressure which is sufficient to counteract the resulting pressure even in the strongest steam evolution in any of the grate elements so that never a reversal of the flow direction of the coolant flow can occur.
• the second shorter leg is to be formed as a larger diameter container over the longer leg, not only to accommodate the thinner leg to form a U-shaped pipe system, but also a certain liquid reservoir form, for which in particular over the connecting line 29 upwardly projecting portion 30 of the container 27 is used. Since the condensation device 23 is open during normal operation to the atmosphere, no higher pressure can arise in the cooling system, than by the height of the water column of the longer Leg is given over the lowest point of the coolant flow of the lowest grate element.
• This height which is freely selectable, determines the maximum pressure in the system, while the distance between the lowest coolant flow of the lowest grate element to the connecting line 29, ie the upper point of the shorter leg, generates those fluid pressure, act against the steam bubbles formed in the grate elements and him would have to overcome in order to force a reversal of the coolant flow can. Due to the selectability of this safety height measurement of the back pressure can be set so high that even with the highest expected heat exposure to a grate element such a volume of vapor with appropriate pressure can not arise.

Landscapes

• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Furnace Details (AREA)
• Incineration Of Waste (AREA)
• Processing Of Solid Wastes (AREA)
• Medicines Containing Plant Substances (AREA)
• Gasification And Melting Of Waste (AREA)
• Seasonings (AREA)
• Apparatus Associated With Microorganisms And Enzymes (AREA)
• Baking, Grill, Roasting (AREA)
• Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)
• Non-Alcoholic Beverages (AREA)

Applications Claiming Priority (2)

Publications (2)

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• 1999
  • 1999-06-28 DE DE19929614A patent/DE19929614C2/de not_active Expired - Lifetime
• 2000
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  • 2000-05-18 DK DK00110634T patent/DK1065442T3/da active
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  • 2000-06-23 CZ CZ20002384A patent/CZ289700B6/cs not_active IP Right Cessation
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  • 2000-06-26 TW TW089112497A patent/TW550361B/zh not_active IP Right Cessation
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  • 2000-06-27 JP JP2000192481A patent/JP3451058B2/ja not_active Expired - Lifetime
  • 2000-06-27 UA UA2000063802A patent/UA49982C2/uk unknown
  • 2000-06-27 PL PL341020A patent/PL191610B1/pl unknown
  • 2000-06-27 RU RU2000117399/06A patent/RU2181181C2/ru not_active IP Right Cessation
  • 2000-06-28 US US09/605,950 patent/US6378447B1/en not_active Expired - Lifetime

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