SK92093A3 - Method of desulfurization of flue gases and device for executing this method - Google Patents

Abstract

Method for operating a flue gas desulphurisation installation which is arranged downstream of a boiler furnace, in particular downstream of a power station boiler furnace, and which operates with an aqueous scrubbing liquid which entrains the finely particulate sorbents and the reaction products formed in the desulphurisation. The flue gas purification installation has a sorption scrubbing tower (1), a lower flue gas inlet (2) and an upper flue gas outlet (3) on the sorption scrubbing tower (1), a scrubbing tower sump (4) beneath the flue gas inlet and a scrubbing liquid circulation. The scrubbing liquid circulation is taken off from the lower part of the sorption scrubbing tower. It is conducted by at least one circulation pump via a piping system and via scrubbing liquid introduction nozzles arranged one above the other in the sorption scrubbing tower, which nozzles generate a shower mass flow of the scrubbing liquid. The reaction products of the desulphurisation are taken off as a suspension from the sorption scrubbing tower with a part of the scrubbing liquid and fed to a separator. A part-stream of the shower mass flow is collected in the region between the scrubbing liquid introduction nozzles and the surface of the scrubbing tower sump. This part-stream is taken out directly from the scrubbing liquid circulation and introduced into the separator. An installation for carrying out the method is also specified. <IMAGE>

Description

Technique

The invention relates to a method for carrying out a flue gas desulphurisation apparatus which is arranged downstream of the boiler furnace, in particular behind the furnace boiler furnace, and operates with an aqueous washing liquid which entrains the finely divided particulate sorption agent and reaction products resulting from desulphurisation. wherein the flue gas scrubber comprises a sorption tower scrubber, a lower flue gas inlet as well as an upper flue gas outlet on the sorption tower scrubber, and a liquid transfer circuit, wherein the scrubbing liquid circuit is discharged from the tower scrubber collection tank and passed through at least one circulation pump, inlet pipe system as well as inlet nozzles for the washing liquid arranged one above the other in a sorbent washing tower, the liquids in which they produce a large stream in the form of raindrops and are discharged with a part of the washing liquid from the sorption tower

d.

into the separator.

which separates the reaction products from the washing liquid, while returning the washing liquid withdrawn from the separator back to the washing liquid circuit and introducing the reaction products to recovery and / or deposition.

The tower scrubber collection tank refers to a region of a sorption tower scrubber in which the wash liquid collects.

but also, of course, that the sorbent tower scrubber has a power supply for refilling the washing water and for supplying finely dispersed sorbents and possibly other additives.

The rinsing of the washing water by feeding to the sorption tower washing machine is carried out most often and mainly by the addition of transferring liquid into droplet separators, the rest is added to the sorption tower or into the collecting tank of the tower washing machine. The fine agent is most often added in the form of a suspended suspension and dry to the collection tank of the tower scrubber. The invention is particularly suitable for the flue gas desulfurization of the above-described construction as well as the above-described for the process according to the invention.

BACKGROUND OF THE INVENTION

In a known method for carrying out a flue gas installation (DE 32 18 470 C3) of the purpose which is to be desulfurized, it is located in the upper to middle region of the tower scrubber collection tank in the tower scrubber collection tank for an oxidation air supply with oxidation air hatch.

In this way, the separation of the washing liquid can be carried out in the collecting tank in relation to the pH value. By separating the washing liquid by means of an oxidizing grid, a preferred pH value of 4 to 6 is set in the upper region.

Sulfur oxidation to sulfate occurs here. Under the grid, the pH value is increased by the addition of a sorbent.

Gypsum is to be precipitated in this case, and the suspension with a very high calcium sulfate content of this known precaution is withdrawn from the lower region.

sorption measures

Within the framework of the interpretation, the energy dependent on

It is an object of the present invention to carry out the above process in such a way that the wash liquid circuit can be maintained by means of considerably lower energy and for desulfurization at a favorable pH value.

The object of the present invention is to provide a device which is particularly suitable for carrying out the process according to the invention.

SUMMARY OF THE INVENTION

To solve this problem, the invention teaches, based on the above-described method, according to independent claim 1, that a partial flow of jet, a plurality of raindrops, is trapped in the region between the washing liquid supply nozzles and the tower surface of the tower scrubber. is removed directly from the circuit with a washing liquid and fed to a separator. Various separators can be operated within the scope of the invention. Generally, one or more hydrocyclones are used. It goes without saying that, in the method of the invention, a partial flow of a large stream of raindrops is fed to an installation still installed or to be installed to remove the reaction product suspension from the tower scrubber collection tank. In this way, it is possible to withdraw all the desulfurization reaction products to be removed from the sorption tower scrubber and to feed them to the separator.

In addition to the measures of the separator,

When cleaning flue gases, it is known per se (DE 35 13 544 A1) that a partial flow of a large stream of raindrops is trapped. For this purpose the collector is used. Within these known, however, this part-flow stream is not recirculated and is again circulated as a wash liquid in order to achieve two separate wash liquid circuits.

It is further within the scope of the invention to remove the particulate stream of entrained finely divided sorption agents as far as possible and to return them to a sorbent scrubber while introducing the particulate stream free of finely divided sorbents into a separator. This separation of the finely divided sorption agent can be carried out in a tower scrubber or outside the tower scrubber.

In the method according to the invention, there is in all cases the possibility of varying the amount of partial quantity stream according to the scale of the different operating ratios so as to correspond to the operating ratios. Determining the amount of partial flow stream determines the concentration of solids in the wash liquor.

It is possible within the scope of the invention to work with a wide variety of sorbents. In the desulphurization of the flue gases downstream of the boiler plant, in particular after the boiler plant, it has proven to work with finely divided limestone, so that calcium sulfite is formed as the reaction product and calcium sulfate dihydrate is oxidized in the sorbent buckle. When working with finely divided limestone as a sorbent, the invention teaches that the pH of the washing liquid supplied by the washing liquid nozzles is adjusted to a pH of 5.7-5.9. This is advantageous for desulfurization reactions.

The pH of the partial flow stream is decisively influenced by the amount of SO 2 in the raw gas, the circulating amount, and the amount of sorption agent added. The pH of the entrapped liquid can be expected to be adjusted by at least 0.5 to a maximum of 2 pH units below the pH of the circulating wash liquid. The energy cost to maintain the wash liquid circuit is greatly reduced.

The invention also relates to such a flue gas desulfurization plant of the above-described construction and the above-described use. The flue gas desulphurisation apparatus according to claim 6, characterized in that a device for collecting a stream of a partial flow of a large stream of raindrops is arranged in the sorption tower scrubber in the region between the washing liquid supply nozzles and the surface of the tower scrubber collector. an apparatus for introducing the trapped partial-stream stream into the separator, wherein all reaction products that are discharged from the sorbent tower scrubber can be withdrawn with the partial-stream stream.

According to a preferred embodiment of the invention, the device for capturing the flow of the partial quantity is arranged in the center of the sorption tower washer. In this case, the device for capturing the partial flow, a plurality of raindrops, may be formed as an upwardly open shielding cover, and at the deepest point of the shielding cover there is a device for introducing the trapped partial flow into the separator. However, it is also possible to provide an upwardly open, hollow cylinder with a closed bottom as a device for capturing the partial quantity flow. wherein a device is provided in the bottom region for introducing the trapped partial quantity stream into the separator. According to a preferred embodiment of the invention, the partial quantity flow capture device is configured as an upward and downwardly open nozzle whose upper edge protrudes sufficiently over the surface of the tower of the scrubber and whose lower edge is submerged approximately half the height of the tower of the scrubber. wherein, in the region of the center of the nozzle height, a device is provided for introducing the trapped stream of partial quantity. In this connection, the invention further teaches that the diameter of the nozzle is to be chosen such that the particulate stream to be captured is large enough to prevent the washing liquid from being sucked into the immersion tube from the collection tank of the tower scrubber and into the separator.

In all cases, it is possible to provide a device for introducing the trapped partial flow into the separator by means of a valve device or controlled pumps, by means of which the quantity of the partial flow can be adjusted. It is also within the scope of the invention that the device for capturing the partial quantity stream is designed in such a way that, as in the settling tank, gypsum is pre-thickened. It is then possible in certain circumstances to dispense with a separate separator in the form of nydrocyclone.

Overview of the figures in the drawing

In the following, the invention is explained in detail by means of only one exemplary embodiment, shown in the drawings, which shows FIG. 1 is a diagram of a flue gas desulfurization plant operating according to the method of the invention; FIG. 2 shows a vertical section through the sorption tower of the device according to FIG. 1, with further construction details.

DETAILED DESCRIPTION OF THE INVENTION

The flue gas desulfurization plant shown in the embodiment has a sorbent scrubber 1, a lower as well as an upper flue gas outlet 3 on the sorbent scrubber 7, a tower scrubber tank 4 under the flue gas inlet 2 as well as a circuit 5 of the washing liquid. The flue gas desulfurization apparatus operates with an aqueous scrubbing liquid which entrains the finely divided sorption agent and the reaction products resulting from the desulfurization. In the embodiment, finely dispersed

The products are primarily sulfites which are oxidized to calcium sulfate dihydrate during the process.

The wash liquid circuit 5 is passed to the bottom of the sorption pump 6 through the pipe system 7 as well as through the wash liquid supply nozzles.

arranged one above the other in the sorption tower 1. The supply nozzles 8 for the washing liquid form in a sorption tower scrubber

1_ a plurality of raindrops. A partial flow of a plurality of raindrops is withdrawn at the devices and

11, as discussed in more detail below.

The desulphurization reaction products deposited as a slurry are withdrawn from the collection tank 4 of the scrubber scrubber 1 with a portion of the washing liquid and fed to a separator.

9, which separates the reaction products from the wash liquid.

According to a preferred embodiment and according to a preferred embodiment, the separator is formed as a hydrocyclone or as an aggregate of hydrocyclones.

The wash liquid withdrawn from the separator is returned to the wash liquid circuit 5. The reaction products are fed for recovery and / or destruction.

It goes without saying that the sorption tower scrubber 1 has a device for replenishing the supply of washing water and finely dispersed sorption agents, which has not been shown.

In the sorbent scrubber 1, in the region between the inlet nozzles 8 for the washing liquid and the surface 10 of the collecting tank 4, there is a sorbent for collecting a quantity of a stream of raindrops.

d.

for introducing the trapped partial quantity stream to the separator, in particular, in the embodiment it is an apparatus 12 which is likewise the products of the desulfurization process. In the exemplary embodiment and in accordance with the preferred embodiment, FIG. We have removed all desulfurization reaction products to be withdrawn from the sorption tower scrubber.

1. they are fed into the separator 9 with a partial flow.

Apparatus 11 for capturing a partial flow of a tower scrubber 7. In an exemplary embodiment and in accordance with a preferred embodiment of the invention, the device for capturing the partial quantity stream consists of a sleeve

13, which is open up and down and whose upper edge protrudes through the sorption tower 1, while the surface 10 of the collecting tank 4, the lower edge being approximately half the height of the collecting tank 4 is immersed in this. In this case, the arrangement is designed such that, in the region of the middle height of the sleeve 13, a device 12 is provided for introducing the trapped partial quantity stream into the separator 9. It is recommended to select the diameter of the sleeve 13 so that the trapped partial quantity stream is large enough to prevent washing liquid into the immersion tube was sucked from the collection tank 4 of the scrubbing tower 7 and led to the separator 9. In all cases, it is possible to provide a device 12 for introducing a partial flow into the separator 9 with a valve device 14 by means of which amount.

The partial flow current capturing device 11 could also be designed as an upwardly concave shielding cap or as an upwardly open cylindrical sleeve provided with a closed bottom, the device 1 being connected to the shielding cover at the deepest point and to the cylindrical sleeve in the bottom area. 2 for introducing the trapped particulate stream into the separator 9. Here, the trapped excess particulate stream could be discharged through the valve device 14 as a flow to the surface of the collection tank 4 of the sorption tower scrubber 7.

In addition, the invention and the effects achieved are explained by a calculation example of admission;

Example of calculation for sizing of the gripping device in the sorption tower washer;

flue gas volume flow rate SO2 in the flue gas SO2 efficiency rate excluded SO2 amount produced gypsum mass concentration solids (gypsum) in the scrubbing liquid efficiency of the separator (hydrocyclone):

Partial flow to separator (hydrocyclone) Circulation amount of washing liquid in sorption tower washing machine Cross-sectional area of sorption tower washing machine

000 000 m ³ / h / m, s / 2 000 mg / m3 / m, s / 90 % 1 800 kg / h 4 900 kg / h

% wt.

% m3 / h

000 M ³ / h

120 m ²

Dimensioning the cross-sectional area of the gripping device >>

x 120 m ³ = 0.66 m ³

000

Example of calculation

Comparison of a sorption tower scrubber with a catcher and without a catcher;

1. with an intercepting device;

flue gas volume flow SO2 concentration in flue gases efficiency level SO2 pH of washing liquid to separator pH of washing liquid in the circuit

000 000 m ³ / h / m, s /

000 mg / m ³ / m, s /%

<5.3

5, 8 ίο stechi onetri and the necessary circulating amount of washing liquid

000 m ³ / h

2. be2 2catcher:

flue gas volume flow 1,000,000 n ³ / h / a, s / concentration of SO2 in smoke gases 2 000 mg / m ³ / m, s / the degree of SO2 activity 90% pH value of the wash circuit dripped ny 5.3 stoichiometers a <1.05 necessary circulating amount of washing liquid 12,000 m ³ / h

Claims (9)

PATENT CLAIMS 1. A method and a vylconávan - G? I * r and pr to paragraph ¹ s s clean flue-ynoic full FN ktorotrPS® arranged in the furnace of the boiler plant and operating the washing liquid, which is entrained along with the finely divided sorptive agent, and reaction products of the a flue gas scrubber having a sorbent scrubber, a lower flue gas inlet as well as an upper flue gas outlet on the sorbent scrubber, a sorbent scrubber collection tank arranged below the flue gas inlet as well as a scrubbing liquid circuit, the washing liquid is led from the washing liquid collecting tank and through at least one circulating pump, through a piping system, as well as the washing liquid inlet nozzles arranged one above the other in a sorption tower scrubber, which produces a plurality of washing liquid raindrop streams, washing suspension from sorp and are fed to a separator which separates the reaction products from the wash liquid, while washing the wash liquor from the separator and returning it back to the wash liquid circuit and recovering the reaction products to and / or to the scrubber. destruction, with the promise that: The amount of rain drop stream amount is trapped in the region between the rinsing fluid supply nozzles and the surface of the receiving tank of the sorption tower scrubber, and this partial flow stream is discharged directly from the scrubbing liquid circuit and fed to the separator. Method according to claim 1, characterized in that limestone is used as the sorbent and the pH is adjusted to a value of 5.7 to 5.9 in the washing liquid supplied by the washing liquid nozzles. Flue gas desulphurisation apparatus, having the structure mentioned in the preamble of claim 1 as well as the function of the preamble of claim 1, characterized in that in the sorption tower scrubber (1) there is a scrubber in the area between the supply nozzles (8). an apparatus (11) for collecting a partial flow of a plurality of raindrop streams, and this is connected to a device (12) for introducing the trapped partial mass flow into a separator (9). ). Apparatus according to claim 3, characterized in that the device (11) is arranged to capture a stream of partial quantities in the middle of the sorbent tower washer. Apparatus according to one of claims 3 or 4, characterized in that the partial-flow current capturing device (11) is designed as an upwardly curved housing, wherein a device (12) for introducing the captured partial-flow current is connected to the deepest point of the housing. amount to the separator (9). Apparatus according to one of claims 3 or 4, characterized in that the partial flow current collection device (11) is designed as an upwardly open hollow cylinder with a closed bottom, wherein in the bottom region there is a connected device (12) for introducing the trapped partial quantity stream into the separator (9). 7th Apparatus according to either of Claims 3 or 4, wherein: - X, 11 o. <- With the fact that the device (ii) for stopping the flow of the particulate quantity is designed as an upward and downwardly open nozzle ( 13) whose upper edge extends over the surface of the collecting tank (4) of the sorption tower (1) and whose lower edge is at a height corresponding to approximately half the height of the collecting tank into this submerged and trapped stream of partial quantity into the separator (9). The apparatus of claim 7, n and no U j Ú c e sa by making the nozzle diameter / 4 **>> ♦ - - T 4 \ 1 J O O A A - ». O d Λ, _ Λ-. . QU / SaChytefi / · the partial flow was large enough to prevent the washing liquid from being sucked from the collection tank of the sorption tower washer (1) into the immersion tube and discharged to the separator (9). Apparatus according to one of Claims 2 or 3, characterized in that the device (12) for introducing the trapped partial quantity flow into the separator (9) comprises a valve device or a controllable pump (14) by means of which the partial flow quantity is adjustable. amount. List of reference numbers sorption tower scrubber 1 lower inlet 2 upper outlet 3 Λ. flushing circuit 5 circulating pump 6 piping system 7 inlet nozzles 8 separator 9 collecting tank surface 10 device 11 for capturing partial flow current device 12 for introducing the captured current nozzle 13 valve device 14