MXPA98005773A

MXPA98005773A - Apparatus to remove so2 from combustion gas to produce a lacquer ammonium sulphate solution can be processed additionally to produce uti substances

Info

Publication number: MXPA98005773A
Application number: MXPA/A/1998/005773A
Authority: MX
Inventors: Risse Theo; Ferrao Lourenco
Original assignee: Ae&Ampe Lentjes Gmbh
Priority date: 1997-07-19
Filing date: 1998-07-17
Publication date: 1999-06-01

Abstract

An apparatus for removing SO2 from combustion gas and for producing an ammonium sulfate solution comprising: a scrubbing and scrubbing tower (1) which comprises at least one wash zone (2) and placed below the washing area a gas permeable collection tray (8), for fluid, a device (4) for the supply of ammonia water to the washing zone, an oxidation device (5), a fluid circuit (9) of absorption, a duct (6) of combustion gas for the supply of combustion gas to the tower for washing and purifying gases, which supplies above the container (11) of washing sedimentation to the interior of the washing tower and gas scrubbing (1), a spray device (7) placed in the combustion gas duct (6) for the supply of a rapid cooling fluid which cools the flow of the combustion gas and saturates it with steam of water, and a device (12) for the purpose of returning the f from the washing sedimentation container (11) to the spray device (7) placed in the flue gas duct. Ammonium sulfate can be supplied from the oxidation device (5) to the wash settler (11) by means of a supply line (13). The washing sedimentation container (11) is connected to an elutriation line (14), from which it is possible to extract a concentrated solution of suitable ammonium sulfate to produce fertilizer. In addition, a discharge line (15) is connected to the oxidation device (5), for the purpose of extracting an ammonium sulfate solution substantially free of contamination suitable for the production of ammonium sulfate.

Description

* - 1 - APPARATUS TO REMOVE SQ FROM COMBUSTION GAS TO PRODUCE A SOLUTION OF SULFATE D? AMMONIUM WHICH CAN BE PROCESSED ADDITIONALLY TO PRODUCE USEFUL SUBSTANCES DESCRIPTION OF THE INVENTION The invention relates to an apparatus for the removal of S02 from combustion gas and to produce an ammonium sulfate solution which can be further processed. to produce useful substances. An apparatus known from DE-C 37 33 319 comprises a prewash unit for the purpose of separating hydrogen halides, and a scrubbing and scrubbing tower connected downstream of the prewash unit and comprising three washing areas. A washing fluid circuit is connected in the middle wash zone of the scrubbing and scrubbing tower and is supplied with ammonia water as an absorbent. A partial flow is removed from the washing fluid circuit and directed to an oxidation device. Oxidation of ammonium sulphite and Ammonium acid sulfite contained in the absorption fluid to form ammonium sulfate is carried out in the oxidation device. Water is used in the prewash unit and returned in a washing water circuit placed in the prewash unit from a fluid settling tank of the prewash unit to a spray device of the prewash unit. A partial flow is withdrawn from the fluid sedimentation vessel and is directed to the absorption fluid circuit of the middle wash zone of the scrubbing and scrubbing tower connected downstream. The toxic substances are separated in the passage of the prewash unit within the absorption fluid circuit of the scrubbing and scrubbing tower and are excluded from the oxidation device with the ammonium sulfate solution. During further processing to form ammonium sulfate by concentration and granulation, an impure final product is produced, which can still be used as a fertilizer. An apparatus is known from EP-A 620 187 which likewise comprises a prewash unit, for the purpose of separating hydrogen halides, and a scrubbing and scrubbing tower connected downstream for the purpose of removing SO2. . The sedimentation container of the scrubbing and scrubbing tower is equipped with a ventilation system for the sedimentation tank. The washing of the gas is done using ammonium sulfate which is extracted from the sedimentation tank of the scrubbing and gas scrubbing tower and goes to the spray nozzles of the scrubbing and gas scrubbing tower. A partial flow of ammonium sulfate is directed to the fluid settling vessel of the prewash unit, which comprises a spraying device and a device for the purpose of returning the fluid from the fluid settling vessel to the spraying device. The ammonium sulfate solution is concentrated as it passes through the circuit. A partial flow of the concentrated ammonium sulfate solution is subjected to the removal from the fluid settling vessel of the prewash unit, further concentrated by hydrocyclones and dried to form ammonium sulfate. The final product in the same way is combined with the toxic substances separated in the prewash unit. The known apparatus comprising a separate prewash unit for the purpose of separating hydrogen halides and comprising a separate scrubbing and scrubbing tower for the purpose of removing S02 from the flue gas is expensive. An additional advantage is that with the known apparatus it is only possible to produce a final product of impure ammonium sulfate which, in the best of cases, can still be used as a fertilizer. The object of the invention is to provide an apparatus with which it is possible to produce two solutions of ammonium sulfate of different qualities. The device must have the most convenient structure possible. The subject matter of the invention and the solution of this object is an apparatus for the purpose of removing S02 from the combustion gas and to produce a solution of ammonium sulfate which can be further processed to produce useful substances., which comprises: a washing and purifying gas tower which comprises at least one washing zone through which the combustion gas flows from the lower part to the upper part, a distributing device which is placed above the washing area for the purpose of supplying absorption fluid and a gas cleaning and purification tower comprising a gas permeable collection tray, placed under the washing zone, for fluid, a device for the supply of ammonia water to the washing zone, an oxidation device for oxidizing ammonium sulfite and ammonium acid sulfite contained in the absorption fluid to form ammonium sulfate, an absorption fluid circuit which connects the collection tray with the oxidation device and the oxidation device with the distributor device placed above the washing area; a combustion gas pipeline for the supply of combustion gas to the scrubbing and gas scrubbing tower which supplies it above the scrubbing tank inside the scrubbing and scrubbing tower, a spray device placed in the combustion gas pipeline for the purpose of supplying a rapid cooling fluid which cools the flow of combustion gas and saturates it with water vapor and which is transported as droplets in the flue gas flow and passes into the wash settling vessel, a device for the purpose of returning the fluid out of the washing sedimentation vessel to the spraying device placed in the flue gas duct, wherein the ammonium sulfate can be supplied to the washing sedimentation by means of a supply line or pipe from the oxidation device and an elutriation line is connected to the washing sedimentation basin, line from which it is possible to extract a solution of ammonium sulfate which has been concentrated when passing through the circuit and is suitable for the production of fertilizer, and in which a discharge line with the purpose of extracting a solution of ammonium sulfate which is substantially free of contamination and which is suitable for the production of pure ammonium sulfate is connected to the oxidation device. The doctrine according to the invention uses the wash settling vessel as a collection vessel for the ammonium sulfate solution used for the prewash unit and as a quench fluid. The wash settling vessel is incorporated into the fluid circuit, in which, by virtue of the mass transfer within the flow of hot combustion gas during the rapid cooling process, the ammonium sulfate solution is concentrated. The absorption fluid used to separate the S02 is collected separately in a collection tray placed below the washing zone and directed to the oxidation device. In the apparatus according to the invention, a concentrated but contaminated solution of ammonium sulfate can be extracted from the sedimentation vessel of the scrubbing and scrubbing tower, and furthermore an ammonium sulfate solution substantially free of contamination, the concentration of which of ammonium sulfate is lower, it precipitates in the oxidation device. The production of the two different solutions of ammonium sulphate is variable with respect to the proportion in quantity, so that it is possible to produce ammonium sulphate which suits the specifications and satisfies the requirements of practical operations. According to a preferred embodiment of the invention, an additional device is connected for the purpose of supplying solutions of NaOH and / or KOH to the spraying device of the flue gas duct. The KOH and NaOH help the halogen binding and in the neutralization process. Preferably, KOH is used, which is also acceptable as a potassium component in the ammonium sulfate fertilizer. The washing zone preferably comprises a packed bed which is sprayed with the absorption fluid. In addition, it is possible, for the purpose of separating aerosols, to install a humid electronic filter in the scrubbing and scrubbing tower which is placed upstream of the cleaned gas outlet on the upper side of the scrubbing and gas scrubbing tower. . In a further embodiment, the invention discloses that the second absorption fluid circuit is located in the wash zone and that an absorption fluid containing ammonium sulfite can be directed through the absorption fluid circuit, while bypassing the fluid. oxidation device, directly to the distributor device above the washing area. The apparatus formed with two absorption fluid circuits makes a process possible, in which the absorption fluid is added to the upper side of the washing zone, absorption fluid which consists of a mixture of ammonia water, washing fluid containing ammonium sulfite, which is extracted from the washing tower and purification of gases below the wash zone and return without intermediate treatment, and a solution of ammonium sulfate which is returned from the oxidation device, where the mixing ratio between the ammonium sulphate and the sulphate of Ammonium is adjusted in the range from 15: 1 to 3: 1. Preferably, the mixing ratio of ammonium sulfite / ammonium sulfate is in the range between 10: 1 and 5: 1. The absorption fluid is characterized by a high capacity to absorb S02 and does not show a tendency to form aerosols. The invention is explained in the following with reference to the only exemplified embodiment illustrated in the drawing. The single figure shows a schematic illustration of the apparatus for the purpose of removing S02 from combustion gas and for the purpose of producing an ammonium sulfate solution which can be further processed to form useful substances. The fundamental structure of the apparatus includes a gas cleaning and scrubbing tower 1 comprising at least one wash zone 2 through which the combustion gas flows from the bottom upwards, and a distribution device 3 positioned by above the washing zone 2 with the supply of absorption fluid, a device 4 for the supply of ammonia water to the washing zone 2, an oxidation device 5 for the oxidation of ammonium sulfite and sulfite ammonium acid present in the absorption fluid to form ammonium sulfate, a combustion gas duct 6 for the supply of combustion gas to the scrubbing and scrubbing tower 1, a sprinkling device 7 placed in the combustion gas duct 6 for the supply of a rapid cooling fluid which cools the combustion gas stream and saturates it with water vapor. Below the washing zone 2 a gas permeable collection tray 8 is placed for the fluid, the washing zone 2 selects an absorption fluid circuit 9 which connects the collection tray 8 with an oxidation device 5 and the oxidation device 5 with the distributor device 3 positioned above the washing zone 2. In addition, the washing zone 2 is assigned a second circuit 10 of absorption fluid through which an absorption fluid containing ammonium sulfite can be guided, while bridging the oxidation device, directly to the dispensing device 3 placed above it. zone 2 washing. The combustion gas duct 6 for the supply of combustion gas to the gas scrubbing and purification tower 1 supplies above the washing sedimentation container 11 to the scrubbing and scrubbing tower 1. The rapid cooling fluid it is supplied from the spray device 7 placed in the flue 6 of the combustion gas and is transported in the flow of combustion gas as it falls and passes inside the washing sedimentation vessel 11. By means of a return device 12, the fluid is returned to the washing sedimentation container 11 to the spray device 7 placed in the combustion gas duct 6.

By means of a supply line 13, ammonium sulfate can be guided out of the oxidation device 5 to the wash settlement vessel 11. An elutriation line 14 is connected to the washing sedimentation vessel 11, from which it is possible to extract an ammonium sulfate solution which has been concentrated as it passes through the circuit and which is suitable for the production of fertilizer. A solution of ammonium sulfate substantially free of contamination from the oxidation device 5 can be extracted. For this purpose, a discharge line 15 is connected to the oxidation device 5, a discharge line through which a solution of ammonium sulfate is extracted which is suitable for the production of pure ammonium sulfate. The apparatus illustrated in the figure serves to remove S02 from the combustion gas, which may originate, for example, from a waste incineration plant, a Claus plant, a power plant, a mud incineration plant or a waste burning plant. sulphite. The dust is preliminarily removed to the combustion gas to a value which is produced from a permissible specification for fertilizer when contaminants are included which contain heavy metals included in the combustion gas and are placed in proportion to the concentration of S02. The preliminary dust removal is carried out in a temperature range of 160 and 350 ° C, so that condensation of sulfuric acid droplets can not occur.

The inlet temperature inside combustion gas duct 6, in which rapid cooling occurs, constitutes from 110 ° C to 180 ° C. The combustion gas directed to the apparatus is sprayed into the combustion gas duct 6 with a solution of NaOH or KOH, which is supplied via a conduit 16, in order to remove any hydrogen halide present. In addition, the ammonium sulfate solution is directed to the combustion gas by means of the spray device 7, where the combustion gas is cooled and saturated with water vapor. The fluid temperature is maintained in a range between 45 ° C and 60 ° C, where the saturation temperature of the gas determines the temperature of the quench fluid. The combustion gas which has been cooled, saturated with water and which is free of hydrogen halide, subsequently flows into the washing zone 2 of the washing tower and purifies gases 1. In the washing zone 2, the The combustion gas charged substantially with S02 is contacted with an absorption fluid which consists of a mixture of ammonia water, an aqueous solution of ammonium sulfate and a freshly formed ammonium sulfite solution. A partial flow of the absorption fluid extracted from the gas permeable collection tray 8 is provided below the washing zone 2 in the absorption fluid circuit 9 to the oxidation device. The oxidation of the ammonium sulfite and the acid ammonium sulphite present in the fluid to form ammonium sulfate is carried out in the oxidation device by adding an oxygen-containing gas. The other portion of the absorption fluid is directed through the conduit 10 in the circuit, mixed with ammonia water from the conduit 4 and with an ammonium sulfate solution from the oxidation device 5 and supplied to the distributor device 3, formed as a spray device, above washing zone 2. The washing zone 2 contains a packed bed, which increases the contact surface between the combustion gas and the absorption fluid and improves the absorption of S02. It is possible to use the packaging to reduce the height of the washing zone 2 and therefore reduce the installation height of the washing and gas cleaning tower 1 in general. A commercially available package consists of a material which is inert with respect to acid gases and can be used in the packed bed. In order to obtain an effective absorption of S02, the pH value of the absorption fluid on the addition side is adjusted between pH 5 and pH 6.5. The pH adjustment is made by adding ammonia water. An air line or pipe 17 comprising a fan is connected to the oxidation device 5. The air supplied via line 17 is brought into intense contact with the fluid containing NH4HS03 and (NH4) 2S03. The ammonium sulfate solution produced is collected in the settling vessel of the oxidation device 5. The concentration of ammonium sulfate is determined, for example, by measuring the density. With an ammonium sulfate concentration between 25 and 30% by weight, the ammonium sulfate solution is withdrawn from the settling vessel of the oxidation device 5. The partial flow withdrawn via conduit 15 can be directed to an ammonium sulfate recovery plant [not illustrated] in which pure ammonium sulfate is produced by removing the water. A partial flow of extraction is directed through the conduit 13 to the washing settling vessel 11 and is used in the fluid circuit, which is connected to the washing settling vessel 11 and includes a return line 12, such as a rapid cooling fluid for the purpose of cooling the combustion gas, wherein a concentration of the ammonium sulfate solution occurs to form an ammonium sulfate concentration of up to 42% by weight. The amount of fluid in the settling vessel of the oxidation device 5 can be kept constant by means of a corresponding supply line by supplying water or washing fluid from a buffer vessel 18. In the exemplary embodiment illustrated in the figure, the gas scrubbing and cleaning tower 1 comprises a second washing zone 2 ', which likewise comprises a packed bed. A washing solution with a pH value between pH 4 and pH 6 is added by means of a distributor device 3 'to the bed of the second washing zone 2' and is brought into contact with the cleaned gas. The washing fluid charged from the second washing zone 2 'is withdrawn into a collection tray 8' placed below the second washing zone 2 'and directed to the buffer vessel 18. The pH value of the wash fluid is adjusted by supplying ammonia water via line 4. The fluid level in the settling vessel of the buffer vessel 18 is controlled by adding water via line 19. The combustion gas subsequently cleaned goes to the chimney and discharges into the environment.

Claims

CLAIMS 1. An apparatus for the purpose of removing S02 from the combustion gas and to produce an ammonium sulfate solution which can be further processed to form useful substances, characterized in that it comprises: a gas scrubbing and cleaning tower which comprises at least one washing zone through which the combustion gas flows from the lower to the upper part, a distributing device which is placed above the washing zone for the purpose of supplying absorption fluid and a tower of washing and purifying gases comprising a gas-permeable collection tray, placed under the washing zone, for fluid, a device for the purpose of supplying ammonia water to the washing area, an oxidation device for the oxidation of ammonium sulfite and ammonium acid sulfite present in the absorption fluid to form ammonium sulfate, an absorption fluid circuit which onecta the collection tray with the oxidation device and the oxidation device with the distributor device placed above the washing area, a flue gas duct for the supply of combustion gas to the tower for washing and purifying gases and which supplies it within the washing and purifying tower of gases above the washing sedimentation container, a spray device placed in the combustion gas duct for the purpose of supplying a rapid cooling fluid which cools the flow of combustion gas and saturates it with water vapor and which is transported as droplets in the flow of combustion gas and passes to the interior of the washing sedimentation container, a device for the purpose of returning the fluid out of the container of washing sedimentation to the spray device placed in the flue gas duct, where ammonium sulfate can be supplied or to the washing sedimentation vessel by means of a supply line or pipe from the oxidation device and an elutriation line is connected to the washing sedimentation vessel, line from which it is possible to extract an ammonium sulfate solution which it has been concentrated when passing through the circuit and is suitable for the production of fertilizer, and in which a discharge line for the purpose of extracting an ammonium sulfate solution which is substantially free of contamination and which is suitable for the production of pure ammonium sulfate is connected to the oxidation device.
2. The apparatus according to claim 1, characterized in that the additional device is connected to the spray device for the purpose of supplying NaOH and / or KOH solutions.
3. The apparatus according to claim 1 or 2, characterized in that the washing zone comprises a packed bed which is sprayed with the absorption fluid.
4. The apparatus according to any of claims 1 to 3, characterized in that the washing zone is located in a second absorption fluid circuit through which absorption fluid containing ammonium sulfite can be guided while the device is bypassed. of oxidation, directly to the distributor device placed above the washing area.
5. The apparatus according to any of claims 1 to 4, characterized in that a wet electronic filter is installed in the washing and purifying gas tower for the purpose of separating aerosols, which filter is placed upstream of the pure gas outlet on the side of the head of the washing tower and cleaned of gases. SUMMARY OF THE INVENTION An apparatus for removing S02 from combustion gas and for producing an ammonium sulfate solution comprising: a scrubbing and scrubbing tower (1) which comprises at least one wash zone (2) and placed below the washing area a tray (8) of gas permeable collection, for fluid, a device (4) for the supply of ammonia water to the washing zone, an oxidation device (5), a circuit (9) of absorption fluid, a duct ( 6) of combustion gas for the supply of combustion gas to the washing and purifying gas tower, which supplies above the container (11) of washing sedimentation to the interior of the washing and gas cleaning tower (1), a spray device (7) placed in the combustion gas duct (6) for the supply of a rapid cooling fluid the which cools the flow of the combustion gas and saturates it with water vapor, and a device (12) for the purpose of returning the fluid from the washing sedimentation container (11) to the spray device (7) placed in the combustion gas pipeline. Ammonium sulfate can be supplied from the oxidation device (5) to the wash settler (11) by means of a supply line (13). The recipient (11) Washing sedimentation is connected to an elutriation line (14), from which it is possible to extract a concentrated solution of suitable ammonium sulfate to produce fertilizer. In addition, a discharge line (15) is connected to the oxidation device (5), for the purpose of extracting an ammonium sulfate solution substantially free of contamination suitable for the production of pure ammonium sulfate.