DE4110939A1 - Reheating gaseous media in flue gas desulphurisation reactors - esp. for coal-fired power stations, using turbine pass-out stream for indirect contact heating of fluidised bed - Google Patents

Abstract

The gaseous medium is treated by contacting with additives, and following a period of desulphurisation in a reactor, the coarse particulates are taken-up and separated by a fluidised bed on the flow of the reactor. Novelty is that the fluidised bed, which is provided with a submerged heating surface, is back-flushed by fluidising with purified smoke gas, that the submerged heating surface is warmed by pass-out steam from an associated power turbine, and that the precipitated coax particulates are blown from the edge zone of the bed in the direction of the funnel shaped centre of the bed, and/or moved tangentially to the funnel wall towards the centre. ADVANTAGE - Total dirty smoke flow from the furnace can be put to the absorber, without the need to split the flow to provide recalorification of the treated portion of the smoke at the stack. Additional capital equipment downstream of the absorber is not required. Heating of the treated smoke gases is energy efficient. Pptd. damp particulates are dried in the fluidised bed, avoiding fouling by surface bake-on. Ash removal follows without the need for mechanical devices. The funnel reactor can be free-standing.

Description

The invention relates to a method and an arrangement for reheating gaseous media, in particular in and / or after spray absorption dryers to flue gas desulfurization.

Desulphurization of flue gases from combustion plants gene by means of so-called spray absorption processes the temperature of the flue gas by spraying it with water or water-solids suspensions lowered. Preferential Temperatures should be achieved wisely, which only a little are above the water dew point temperature. With that those temperatures sometimes considerably lower than that for further flue gas discharge via dedusting lay and chimney permissible, so that reheating the flue gas becomes necessary.

As is known, the following are used for reheating:

• - Steam or flue gas heated heat exchangers that the Absorbers for flue gas desulfurization are subordinate;
• - The admixture of hot flue gases either over a external flue gas system (branch from the steam boiler, DD-PS 2 58 893) or through an internal flue gas system (Arrangement of inner walls, DD-PS 2 59 570).

The disadvantage is that

• - when using steam or flue gas powered heat exchanger additional systems are required, the An increase location costs and because of limited space difficult when retrofitting existing systems or in connection with additional expenses are orderable,  
• - when using the admixture of hot flue gases Partial flow of the flue gas, which is used for reheating is required and from the steam boiler before air supply warmer or economiser, desulfurization withdrawn and thus affect the degree of desulfurization is pregnant.

Also known is a method in which the lower Part of the desulphurization reactor with a fluidized bed is issued (EP-PS 1 28 698). This turns ash or inert material formed by means of hot maintain gas against the desulfurized and cooled flue gas flows into the reactor. The use of flue gas, which precedes the Reactor at a point with the required smoke gas temperature branch is branched off. The smoke temperature should ture should be as high as possible in order to warm up after mixing with the cooled flue gas keep the mass flow as low as possible. On the other hand minimizing the efficiency of the we belbetts, which may also dry at the same time moist ash particles are used, restricted and the stability of the fluidized bed when the load is reduced Asked a question. The energy required to maintain the fluidized bed is high. For an effective heating is a large-volume fluidized bed with a correspondingly high appara tive effort required.

The same reactor with one on the bottom Fluid bed is known from DE-OS 39 10 716. The disadvantage is the high pressure drop (i.e. relatively high pressure of the flue gases), the flue gases who the passed over a water bath. There is no how the warming of the desulfurized gases.

The invention is based, in the Rauchgasent the task sulfurization reactor after the spray absorption moist coarse components before entering the electrostatic precipitator and subsequent components to be dried, to avoid caking.

This is achieved according to the invention in that the a fluidized bed equipped with an immersion heating surface whirled up a sucked back cleaned flue gas, the immersion heating surfaces by steam from a power Turbine tapping using heat coupling warmed up and the coarse constituents of the edge areas the fluidized bed in the direction of the funnel-shaped blown and / or formed center of the fluidized bed led tangentially to the center of the funnel wall will. The flue gas is in the area of the secondary heating areas taken. With a tangential guide in the funnel an ash-laden surface layer is removed in front of the economizer peels and passed into the double-walled funnel. The arrangement belonging to the invention is thereby known shows that the funnel is double-walled, in the floor area a horizontal plane, the sloping In bores and / or slots and the inner jacket the horizontal plane nozzles as well as a central tube have and that in the fluidized bed an immersion heater surface is arranged.

The amount of ash from the reactor is shown by the edge hot gas injection dried and towards the funnel center blown and / or tangential to the funnel wall to the center (using a funnel line is secured).

The dried ash is in the area of the nozzles and / or the central blowpipe from the inflowing Hot gases (as heating gas of the desulphurized flue gases) detected and blown into the gas discharge nozzle. From there the ash is ge with the flue gas stream from the reactor wear and separated as dry ash in the electrostatic precipitator. The amount of dry gas and / or transport gas injected  is at the same time a partial and / or total amount of gas Hot gas admixture. This amount of gas can be as special advantageous in the area of secondary heating surfaces be taken, which makes the differential pressure so great that no further drives are required. In the Tangential guidance in the funnel is particularly advantageous an ash-laden surface layer in front of the economizer as the amount of ash and sand carried is a Reini effect by impulse and erosion, which the Keeps the funnel wall clear. In a further embodiment becomes a floating amount of ash through the nozzles flow reached. The amount of ash suspended can be pulled off over the standpipe.

In the following, the invention is intended to be based on an embodiment example are explained in more detail.

It shows:

Fig. 1, the incorporation of out with the fluidized bed reactor outfitted in the power station process,

Fig. 2 shows the reactor of funnel formation, fluidized bed and Tauchheizfläche in section,

Fig. 3, the funnel formation in plan view,

Fig. 4 shows the funnel with the standpipe as a die body in section,

Fig. 5 the funnel with internals in oblique view,

Fig. 6 funnel with peeling device on average.

The flue gas generated in the furnace 1 is passed through the flue gas duct 2 into the spray absorber 3 , where it is brought into contact with injected water or water-solid suspensions 4 ( FIG. 1). The temperature of the flue gas, which is reduced in temperature by loading with water or water-solid suspension, leaves the sorber 3 via the flue gas duct 6 and is removed via the dust separator 47 by means of a suction fan 48 via the chimney 49 into the open. In the lower part of the absorber 3 , a fluidized bed 5 consisting of ash or other inert material is arranged, which is equipped with immersion heating surfaces 7 . Purified flue gas is used as the fluidizing medium, which branches off behind the suction draft 48 and is added to the fluidized bed 5 by means of a recirculation fan 8 via the fluidized bed 9 . The immersion heating surfaces 7 are integrated via the bleed line 10 of the turbo set 11 and the condensate return 12 in the power plant block. The integration of the condensate return 12 is preferably carried out between two preheaters 13 of the low pressure preheating column of the regenerative feed water preheating of the power plant block. The reactor 3 with the head part 42 , the cylinder part 43 and the funnel 44 has the flue gas channel 2 and the centrically designed revenge gas channel 6 ( FIG. 2; 3). The funnel 44 consists of the inclined part 45 and the nozzle base 9 with the nozzles 41 and the suction pipe. The suction pipe 24 extends into the funnel 44 . The inclined part 45 consists of the outer jacket 23 and the inner jacket 22 , the gap 33 being formed. The inner jacket 22 has the holes 14 in the inclined part 45 . The flue gases 46 to be desulfurized pass through the flue gas duct 2 into the cylinder part 43 of the reactor 3 and are guided into the electrostatic filter 47 via the centrally arranged flue gas duct 6 . A portion of ash 16 falls into the hopper 44 . Hot flue gases 17 are forced through the bores 14 via the intermediate space 33 . So that the entire inclined part 45 is heated and a constant hot gas layer 18 is maintained. These hot gases 17 dry the ashes 16 and direct them to the bottom of the nozzles 9 . By means of the amount of hot gas 19 in the intermediate space 20 , the nozzles 41 are acted on in such a way that the amount of ash 16 dries up in compressed form and is withdrawn as ash stream 21 via the suction pipe 24 . The funnel having the inner wall 22 and the outer wall 23 and supplied with the amount of hot gas 27 is provided with holes 26 and a line 25 charged with hot gas 29 in the funnel center 28 arranged blow body 24 ( Fig. 4). The partial ash quantity 16 is detected by the hot gas quantity 27 flowing out of the nozzles and transported in the direction of the funnel center 28 , with intensive drying taking place. At the same time, hot gas (steam, air) 29 is introduced via the blow body 24 . This hot gas detects the ash parts 30 directed into the center and hurls them into an ash hot gas stream 31 in the discharge nozzle 6 , so that this ash is discharged with the gas stream 32 into the electrostatic precipitator.

Via the line 35 is a highly enriched with ash, sand 36 edge flow 37 (peeled) in the inter mediate space 33 ( Fig. 4; 5). This amount of hot gas-ash 37 exits via the slots 34 as an edge flow 38 in the direction of the funnel center 28 . This marginal flow 38 detects the amount of ash 16 , dries it up and directs it towards the blowing body 24 . Due to the intensive edge flow with a high proportion of sand, the inner wall 22 is constantly blown free or ash deposits are removed. With the hot gas supply 29 via the line 25 and the blowing body 24, it is followed by blowing the downward amount of ash-sand 39 in the direction of the flue gas duct 6 . Baffles 40 are also arranged for flow conduction in the ash funnel having the fluidized bed. They support the direction of flow for ash removal.

Advantages of the procedure are:

• - The entire flue gas flow from the combustion system is passed through the absorber without a partial flow is required for reheating.
• - The reheating does not require any additional Downstream, expensive systems and absorber Equipment.  
• - The amount of heat required is based on energy economy Way by using the cogeneration poses.
• - For drying, possibly even more moist Particles become favorable for mass and heat transfer conditions of the fluidized bed.
• - Ash is discharged without mechanical devices.
• - The reactor funnel wall is kept free at all times.
• - There is no additional ash on the reactor funnels plant required.

Claims (10)

1. A method for reheating gaseous media in flue gas desulfurization reactors, the gaseous medium being acted upon by additives and the coarse constituents inherent in the gaseous medium being collected and separated in a reactor after a desulfurization section through a vortex arranged at the bottom of the reactor, characterized in that the vortex layer equipped with an immersion heating surface is whirled up with a sucked-back cleaned flue gas, the immersion heating surfaces are warmed up by steam from a turbine tapping using the cogeneration and the resulting coarse parts of the edge areas of the fluidized bed are blown towards the funnel-shaped center of the fluidized bed and / or be guided tangentially to the funnel wall into the center. 2. The method according to claim 1, characterized in that that the flue gas in the area of the secondary heating surfaces is removed. 3. The method according to claim 1, characterized in that that with a tangential guide in the funnel ash-laden surface layer peeled off in front of economizer and is used. 4. The method according to claim 1, characterized in that that the drying gases are removed from the air system will. 5. Arrangement for reheating gaseous media in flue gas desulfurization reactors, being in the bottom area of the reactor with a dip tube Funnel and a fluidized bed is arranged,  characterized in that the funnel is double-walled is formed, a horizontal in the floor area Level, the oblique inner jacket holes and / or Slots and the inner surface of the horizontal plane Have nozzles and a central tube and that an immersion heating surface is arranged in the fluidized bed is. 6. Arrangement according to claim 4, characterized in that the double-walled funnel, the horizontal plane and the centric pipe is connected to a hot gas pipe are. 7. Arrangement according to claim 5, characterized in that the hot gas line with a peeling device that is arranged in front of economizer, is connected. 8. Arrangement according to claim 4, characterized in that the immersion heating surfaces with the steam turbine and with the regenerative preheating of the power plant block ge are coupled. 9. Arrangement according to claim 4, characterized in that baffles are arranged in the funnel. 10. The arrangement according to claim 4, characterized in that the central tube is designed as a suction or blowing tube det.