DE202015106840U1 - Apparatus for treating solids laden process waste water - Google Patents

Abstract

Process for the treatment of solids laden process waste water, which is produced in the purification of synthesis gas in a gasification plant for the production of synthesis gas from carbonaceous fuels, comprising the following components: • a gasification reactor (1) with a reaction chamber (2) for generating a raw synthesis gas under high temperature and high pressure and with a quenching chamber (4) adjoining the reaction chamber (2) for cooling the crude synthesis gas comprising quenching means (6) and a water bath (5) with water supply, • at least one gas scrubber (11) for separating solids from the raw synthesis gas stream, which is downstream of the quench chamber (4), at least one hydrocyclone (16) to which the process waste water from the at least one gas scrubber (11) can be supplied, • a line which overflows the hydrocyclone (16) for clear water (17) with the Quench devices (6) in the quench chamber (4) connects, characterized gekennz eichnet that an underflow (19) of the hydrocyclone (16) with the water bath (5) of the quench chamber (4) is connected.

Description

The invention is directed to a device for the treatment of solids laden process wastewater, which is produced in the purification of synthesis gas in a gasification plant for the production of synthesis gas from carbonaceous fuels, according to the preamble of claim 1.

The principle of the production of synthesis gas by gasification is that under certain temperature and pressure conditions carbon-containing fuels such as coal, charcoal or petroleum coke with oxygen-containing gasification agents (air, oxygen, steam, etc.) react and thereby the organic components in a mixture of Carbon monoxide and hydrogen (synthesis gas) are reacted, wherein the mineral residues of the fuels are transported in the form of molten slag particles in the raw synthesis gas and must be separated.

A gasification process therefore comprises three complexes: the gasification of carbonaceous substances, the purification of raw synthesis gas and the treatment of process wastewater laden with solid matter. It is customary to call the process wastewater containing mainly slag and ash, depending on its solids loading, "black water" or "greywater", greywater, as a rule, designating a purified black water which is fed into the process again.

The carbonaceous fuels react with the gasification agents in a reaction chamber of a gasifier. The synthesis gas, slag and fly ash produced in this process are discharged through the bottom of the reaction chamber into a cooling or quenching chamber in which the raw synthesis gas and the slag particles transported with it are cooled below the slag melting point in contact with water, for example by atomizing water in the area of the slag Crude gas (spray quench) and / or by passing the Rohsynthesegases through a water bath (immersion quenching). A large part of the ash and slag sinks down in the water bath of the quench chamber and collects at the conical bottom of the water bath. Since ash and slag residues are still present in the raw synthesis gas, it is necessary to purify the raw synthesis gas using gas purifiers. The resulting charged with solid black water, which comes with high temperature and high pressure from the carburetor and the gas purification devices is recycled for economic reasons, i. the black water must be discharged from the pressure system, can then be prepared for example by precipitation, sedimentation or filtration in other cleaning devices and must then be covered again, i. be brought to system pressure. Also common is a combination of relaxation and solids separation, referred to as flash distillation.

The known method for the treatment of process wastewater (black water) are complex and require a relatively large amount of equipment due to the numerous pressure locks, cause high costs and require large amounts of water circulation.

From the DE 24 44 819 A1 It is known to liberate crude synthesis gas from a coal-pressure gasifier in a downstream wet scrubber (washer-cooler) with spray tower and water bath of tar and dust. From the bottom outlet of the water bath is loaded with tar and slag loaded washing water and purified in one or more series-connected hydrocyclones. The purified wash water is then returned to the head of the wash cooler. The water cycle washer-hydrocyclone washing cooler remains completely at the pressure level of the gas generator, the dust and tar constituents from the lower reaches of the hydrocyclones are discharged as a concentrate and aftertreated under normal pressure. The washing water thus recovered is fed to the head of the washing cooler after an increase in pressure as well as the hydrocyclone clear water.

In the DE 35 37 493 A1 a process for the treatment of quench water is described in which a crude gas is cooled in a quench and subjected to gas scrubbing, fresh water and process condensate are fed into the gas scrubber. The resulting process waste water and the withdrawn from the water of the quench water are fed together to a hydrocyclone. Its clear-running feeds to a part spray nozzles in the quench room and the other part is relaxed, cooled and cleaned. The underflow of the hydrocyclone passes the solids enriched concentrate via a discharge lock to an ash discharge device.

Subject of the DE 10 2010 040 493 A1 is an apparatus and method for recirculating process waters of a fly-back reactor wherein soot water containing slag water, residual quench water, wash waters and condensates is freed of solids under process pressure by hydrocyclone or filter press and returned to consumers of the entrainer gasifier. The underflow of one or more hydrocyclones transports the solid concentrate into a sludge tank and over a Relaxation lock to a filter press, in which circulating water is recovered discontinuously.

A disadvantage of the solutions described is that although clarified in hydrocyclones process water is returned for quenching the Rohsynthesegases, but the solids-laden concentrate from the lower reaches of the hydrocyclones with a high water content is discharged without further treatment from the circulation and then under ambient pressure in a sedimentation stage or filter press is separated into solid and liquid phases. The recovered process water must be re-strung and recycled. The effort is economically disadvantageous.

The invention is therefore based on the object, starting from the disadvantage of the known solutions to improve the circulation of process water to the effect that the proportion of discharged process waste water is reduced. The use of hydrocyclones should be maintained because they are due to their continuous operation and closed design optimally suitable for solids separation within a water circulation system under pressure.

According to the invention the object is achieved by a device having the features of the first claim. Advantageous embodiments are the subject of the dependent claims.

By connecting an underflow of a hydrocyclone for the purification of solid laden process wastewater with the water of the quench chamber loaded with solids underflow water of the hydrocyclone is not immediately discharged in an additional lock device, but initially fed to another, already existing separation stage, in the sedimentation again a Solid-water separation takes place before the solid is discharged from the quench chamber discharge cone in high concentration and with low water content with the existing lock device.

The present invention has the advantage of providing a simple and inexpensive process wastewater treatment facility with lower water consumption within a coal gasification process and effectively utilizing existing apparatus and lock devices. The purification of the recirculated process water takes place in a continuous, continuous mode of operation and under the system pressure of the gasification reactor.

The water bath of the proposed scrubber is advantageously used in addition to the gas-solid separation at the same time as a buffer tank for the circulating water. The water bath in the quench chamber, which serves to receive the slag from the raw gas, also acts as a sludge collection chamber for the lower reaches of the hydrocyclone.

With the introduction of the sludge underflow of the hydrocyclone in the quench water, the Schlackeaustragsschleuse the quench is also co-used for the separated in the Rohsynthesegasreinigung solid and thus saved a further discharge device. The quench chamber also serves as an additional sedimentation space for the solids-water separation of the process effluent from the gas purification. With the influx of the hydrocyclone underflow into the quench water bath, an additional dynamic is introduced there, which can be used to prevent slag clogging at the discharge lock of the quench chamber.

In the following, the invention will be explained using the example of an entrainment gasification plant in an extent necessary for understanding the proposed solution. The accompanying drawings represent:

1 : schematic representation of the device for the treatment of process wastewater

2 : Process wastewater treatment with a two-stage arrangement of hydrocyclones

The present invention provides a technical solution for black water treatment within a coal gasification plant.

Like from the 1 As can be seen, the proposed device for the treatment of solids laden process wastewater, which is formed during the purification of synthesis gas, integrated into an entrained flow gasification plant for the production of synthesis gas from carbonaceous fuels. Likewise, the proposed solution can also be used in fluidized bed, fluidized bed or fixed bed gasification plants, provided that a crude gas quench device is present.

In a reaction chamber 2 an air flow gasification reactor 1 is at high temperatures and pressures with the help of a burner 3 from the reaction partners carbon, hydrogen and oxygen in an exothermic partial oxidation of the carbon a Rohsynthesegas generated in a subsequent quench 4 by quenching means 6 and a water bath 5 can be cooled in each case with a water supply in contact with the water. Under quenching facilities 6 are all water consumers who understand the quenching chamber 4 can be assigned For example, spray devices for atomizing quench water in the raw synthesis gas stream or ring manifold for producing protective water films on pipe or container wall surfaces.

The water bath 5 in a lower portion of the quench chamber 4 is intended for the separation of a first part of the resulting from the mineral residues of the coal slag. The in the water bath 5 sedimented slag becomes over the slag discharge 7 discharged from the printing system.

At the raw gas outlet of the quench chamber 4 is a raw synthesis gas line 8th arranged, which the raw gas stream to gas scrubbers 10 . 11 in which the ash and slag particles remaining in the raw synthesis gas stream can be separated.

The solids separation from the crude synthesis gas takes place at least with a gas scrubber 11 which, as implemented in the embodiment, with one or more venturi scrubbers 10 can be combined.

The gas scrubber 11 contains, for example, a wet scrubber with a water bath 13 into which a raw gas dip tube 12 dips, and a arranged above it tray column 22 , wherein the tray column 22 For example, can contain bubble trays and with high pressure water 23 and / or condensate 24 is operated in countercurrent to the crude synthesis gas.

The exit of the venturi scrubber 10 is with the raw gas dip tube 12 the scrubber 11 connected. A pipe for slag-laden process waste water 14 is from the water bath 13 the scrubber 11 to an inlet of a hydrocyclone 16 guided. In the inlet to the hydrocyclone 16 is a pump 15 arranged.

A supply line for the clear water 17 from the overflow of the hydrocyclone 16 is with the quenching devices 6 in the quench chamber 4 connected.

According to the invention, the underflow 19 of the hydrocyclone 16 with the water bath 5 the quench chamber 4 connected. A discharge for heavily laden with solid process wastewater 21 is at a lowest point of a conical bottom of the water bath 13 arranged and to a downstream cleaning device 26 guided.

To improve the cleaning effect of hydrocyclones, it is expedient, according to 2 several, preferably two serially arranged hydrocyclones 16 insert, wherein the inlet of the first hydrocyclone in the flow direction 16 with the gas scrubber 11 and the pipe for the clear water 17 from the overflow of the last hydrocyclone 16 with the quenching device 6 connected is. The mud-leading underflows 19 hydrocyclones 16 open with a common supply line in the water bath 5 the quench chamber 4 ,

For better separation of finely dispersed solids, cyclones with a smaller size can also be connected in parallel, and these cyclone batteries can be combined with a serial arrangement.

For a regulation of the quench chamber 4 guided circulating water, it is advantageous if a throttle valve 18 in the supply line of the clear water 17 from the overflow of the hydrocyclone 16 to the quench chamber 4 is arranged.

From the water bath 5 the quench chamber 4 is another sewer pipe for black water 20 to the downstream cleaning device 26 guided.

The cleaning device 26 is a separate, known from the prior art device for the separation of impurities from the discharged black water, which is usually operated under ambient pressure. Here can flash distillation, sedimentation tanks, filter plants or similar. be used with or without precipitation of the solid particles for solids separation.

For the operation of the device according to the invention:
In the reaction chamber 2 a gasification reactor 1 is in the flame zone of one or more burners 3 produced at high temperatures and high pressures a raw synthesis gas, which subsequently into a quenching chamber 4 overflowed and cooled there in contact with water. It also a large part of mittransportierten slag particles in a water bath 5 deposited.

After leaving the quench chamber 4 The raw synthesis gas is put into two scrubbers 10 . 11 cleaned. The raw synthesis gas is first in a Venturi scrubber 10 with high pressure gray water 9 intensively mixed, wherein the remaining fine ash and slag particles wetted with water and agglomerated. The greywater-laden raw synthesis gas then flows through the raw gas immersion tube 12 in a water bath 13 a second scrubber 11 a, wherein the agglomerated ash and slag particles in a water bath 13 be withheld.

The pre-purified synthesis gas from the water bath 13 (represented by arrows) flows through the tray column 22 above the water bath 13 and is doing countercurrent initially with high-pressure gray water 23 that of the cleaning device 26 is provided, and then with solid free condensate 24 washed from a (not shown) process cooling, the particulate matter is separated from the raw gas. The mechanically purified synthesis gas 25 leaves the gas scrubber 11 above the tray column 22 and is then fed to further chemical cleaning processes. The washing water from the tray column 22 is in a water bath 13 collected.

Instead of the described two gas scrubbers 10 . 11 are also more or other wet scrubber with a common process wastewater collection container used.

In the described arrangement of the embodiment, the entire dust removed from the raw gas is in the water bath 13 collected.

In an expedient embodiment of the gas scrubber 11 The collected black water with different solids content from the water bath 13 taken.

The black water 14 with a lower solids content, approximately from mid-height of the water bath 13 with the help of the pump 15 is sucked off, the hydrocyclone 16 fed. In the hydrocyclone 16 There is a concentration of the solid, which is the hydrocyclone 16 over the lower reaches 19 leaves and in the loaded with slag water bath 5 the quencher 4 is initiated. The clear water 17 from the hydrocyclone 16 can be used for raw gas cooling in the quencher 4 be used by it because of its low solids content the quenching 6 in the quencher 4 is supplied. The clear water 17 It is preferably atomized finely dispersed in the raw synthesis gas stream, whereby it evaporates and thereby absorbs heat from the Rohsynthesegasstrom. Usually, quench nozzle rings are in the region of the gas inlet into the quench chamber 4 arranged there to achieve a "flash cooling" of the raw synthesis gas.

Likewise, the clear water 17 also for the construction of water films on internals or wall surfaces of the quench chamber 4 serve.

With the throttle valve 18 in the supply line of the clear water 17 are the throughput and thus the separation behavior of the hydrocyclone 16 adapted and the volume flows to the quench device 6 and to the water bath 5 in the quench chamber 4 affected.

A removal of the continuously separated from the raw synthesis gas solid from the process water cycle via the sewers (black water 20 . 21 ) from the water baths 5 . 13 ,

The process waste water to be cleaned 20 . 21 must be decompressed for discharge from the pressure system of the gasification plant in an expansion lock (shown symbolically with a dashed line) and reintroduced after cleaning. Therefore, the efforts to optimize the operation of the gas cleaning equipment are aimed at keeping the proportion of circulating water circulated under system pressure as high as possible and the proportion of highly loaded, outside the gasification system in the cleaning device 26 to minimize to be purified black water. Accordingly, only the highly loaded black water 20 . 21 from the cone area of the quench chamber 4 and from the cone bottom of the gas scrubber 11 in the separate cleaning device 26 initiated.

The proposed process water treatment differs from the known solutions at least in that the clear water flow and the underflow stream from the hydrocyclone 16 in two different places in the quench chamber 4 is fed, whereby a separate discharge of the hydrocyclone underflow is eliminated.

To improve the clarification effect of the hydrocyclone 16 can use several hydrocyclones 16 be connected in series, so that the clear water from the first hydrocyclone 16 in the second hydrocyclone 16 is cleaned. For better separation of even the finest dust particles, in the second stage an even more intensive separation of solids in several smaller hydrocyclones 16 be provided in parallel. In this way, the risk of blockages in the quenching devices 6 , especially at Zerstäubungsdüsen be safely reduced.

In addition to the described embodiments for black water treatment, other modifications of the present invention are within the scope of protection, provided that they are in the Quenchwasserzuführung to the quench chamber 4 have a continuous device for the separation of solids from process wastewater, whose outputs with a quenching chamber 4 are connected.

LIST OF REFERENCE NUMBERS

1

 gasification reactor

2

 reaction chamber

3

 burner

4

 quench

5

 water bath

6

 quench

7

 slag discharge

8th

 Rohsynthesegasleitung

9

 High pressure greywater

10

 Venturi scrubber, scrubber

11

 gas scrubber

12

 Raw gas immersion tube

13

 water bath

14

 Process waste water, black water)

15

 pump

16

 hydrocyclone

17

 clear water

18

 throttle valve

19

 underflow

20

 Process wastewater, black water

21

 Process waste water black water

22

 tray column

23

 High pressure greywater

24

 condensate

25

 synthesis gas

26

 cleaning device

n, m

 natural numbers (n, m> 0)

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 2444819 A1 [0006]
• DE 3537493 A1 [0007]
• DE 102010040493 A1 [0008]

Claims (8)

Apparatus for treating solids-laden process waste water which is produced during the purification of synthesis gas in a gasification plant for the production of synthesis gas from carbon-containing fuels, comprising the following components: a gasification reactor ( 1 ) with a reaction chamber ( 2 ) for generating a raw synthesis gas under high temperature and high pressure and with a to the reaction chamber ( 2 ) subsequent quenching chamber ( 4 ) for cooling the crude synthesis gas, which quenching devices ( 6 ) and a water bath ( 5 ) with water supply, • at least one gas scrubber ( 11 ) for solids separation from the Rohsynthesegasstrom, which the Quenchkammer ( 4 ), at least one hydrocyclone ( 16 ), the process wastewater from the at least one gas scrubber ( 11 ), • a line which overflows the hydrocyclone ( 16 ) for clear water ( 17 ) with the quenching devices ( 6 ) in the quench chamber ( 4 ), characterized in that an underflow ( 19 ) of the hydrocyclone ( 16 ) with the water bath ( 5 ) of the quench chamber ( 4 ) connected is. Device according to claim 1, characterized in that the device also comprises a venturi scrubber ( 10 ) for solids separation from the raw synthesis gas. Apparatus according to claim 1 or 2, characterized in that the gas scrubber ( 11 ) contains a wet scrubber with a water bath ( 13 ) into which a crude gas dip tube ( 12 ) and with a tray column ( 22 ), wherein the tray column ( 22 ) with high-pressure gray water ( 23 ) and / or condensate ( 24 ) is operated in countercurrent to the crude synthesis gas. Apparatus according to claim 3 in conjunction with claim 2, characterized in that • a raw gas outlet at the quench chamber ( 4 ) of the gasification reactor ( 1 ) with the venturi scrubber ( 10 ) via a crude synthesis gas line ( 8th ), the outlet of the venturi scrubber ( 10 ) with the crude gas immersion tube ( 12 ) of the scrubber ( 11 ), • a process waste water line ( 14 ) from the water bath ( 13 ) of the scrubber ( 11 ) to an inlet of the hydrocyclone ( 16 ), • the overflow of the hydrocyclone ( 16 ) for clear water ( 17 ) with quenching devices ( 6 ) in the quench chamber ( 4 ) and • the lower reaches ( 19 ) of the hydrocyclone ( 16 ) with the water bath ( 5 ) in the quench chamber ( 4 ) connected is. Device according to one of claims 1 to 4, characterized in that two waste water pipes for process wastewater ( 14 . 21 ) from the water bath ( 13 ) of the scrubber ( 11 ), whereby a line for process wastewater ( 21 ) at a lowest point of a conical bottom of the water bath ( 13 ) and to a downstream cleaning device ( 26 ) and another line for process wastewater ( 14 ) from a mean height of the water bath ( 13 ) to the inlet of the hydrocyclone ( 16 ) is guided. Device according to one of claims 1 to 5, characterized by two or more serially arranged hydrocyclones ( 16 ), wherein the inlet of the first hydrocyclone in the flow direction ( 16 ) with a line for process waste water of the scrubber ( 11 ) and the overflow for clear water ( 17 ) and the lower reaches ( 19 ) of the last hydrocyclone ( 16 ) to the quench chamber ( 4 ) are guided. Device according to one of claims 1 to 6, characterized in that a throttle valve ( 18 ) in the overflow line for the clear water ( 17 ) of a hydrocyclone ( 16 ) to the quench chamber ( 4 ) is arranged. Device according to one of claims 1 to 7, characterized in that a line for process wastewater ( 20 ) from the water bath ( 5 ) of the quench chamber ( 4 ) to the cleaning device ( 26 ) is guided.

Images