EP0000515A1 - Procédé pour enlever le gaz sulfureux d'un courant gazeux et installation pour la mise en oeuvre du procédé - Google Patents

Procédé pour enlever le gaz sulfureux d'un courant gazeux et installation pour la mise en oeuvre du procédé Download PDF

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Publication number
EP0000515A1
EP0000515A1 EP78100389A EP78100389A EP0000515A1 EP 0000515 A1 EP0000515 A1 EP 0000515A1 EP 78100389 A EP78100389 A EP 78100389A EP 78100389 A EP78100389 A EP 78100389A EP 0000515 A1 EP0000515 A1 EP 0000515A1
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zone
acid
content
absorption
nitrogen
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EP78100389A
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EP0000515B1 (fr
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Volker Dr. Fattinger
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Novartis AG
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Ciba Geigy AG
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/46—Removing components of defined structure
    • B01D53/48—Sulfur compounds
    • B01D53/50—Sulfur oxides

Definitions

  • the invention relates to a method for separating SO 2 from a gas stream containing it at least temporarily in a concentration that is inadmissibly high for discharging into the ambient air with the production of sulfuric acid by the nitrogen oxide method, in which the latter contains the SO 2 -containing gas
  • H 2 SO 4 is brought into contact with thin acid circulated through the relevant area of this zone at concentrations below 70% by weight (55 ° Be),
  • the nitrogen oxides released in the denitrification zone are taken up by sulfuric acid and from the absorption zone nitrous acid containing 70 to 85% by weight (55 to 63.5 ° Be) H 2 SO 4 is removed and transferred to the denitrification zone becomes.
  • nitric acid or other nitrogen oxide-containing substances are added at any point in the denitrification zone just defined.
  • the regulation of the color of the exhaust gases of the system that is, the control of the ratio NO: N0 2 in the exhaust gases, is done in most cases in known nitrogen oxide-sulfuric acid plants by adding more or less water in the acid cycle through the denitrification zone and Nitric oxide absorption zone.
  • DE-PS 1,140,909 (Ruhr-Schwefelkla GmbH) describes an adjustment of the ratio of NO: NO 2 and the content of NO + NO 2 in the gas phase by means of opposite changes in the density of the acid. Such changes are said to be the most effective measure to influence the oxidation rate of the process.
  • the acid which circulates in the system according to this DE-PS is a strong acid with a content of 80% by weight H 2 SO 4 and no thin acid of less than 70% by weight H 2 SO 4 , such as it circulates in the S0 2 processing zone of DE-OS 26 09 505.
  • This problem did not occur in previous processes.
  • the invention further aims to achieve an improved, very rapid adaptation of the NO: NO 2 ratio in the exhaust gas emitted from the system, so that this exhaust gas virtually eliminates the yellow flag caused by the presence of NO 2 in the exhaust gas leaves while avoiding inadmissible losses of colorless NO from the system.
  • Another object of the invention is to achieve an improved emission of gases from the system mentioned, in which the nitrogen oxide content is below a legally prescribed maximum limit (e.g. 400 ppm).
  • the invention described below also primarily solves the problem of correcting the composition of the exhaust gases of a nitrogen oxide-sulfuric acid system within a few minutes and also enabling automation of the overall system.
  • the invention is preferably applied to the method described in the introduction, which is described in particular in DE-OS 25 10 294 and 26 09 505.
  • the specific amount of the NO limit or the steepness limit cannot be specified in general, but depends on the system and in particular on the size of the various reaction apparatuses (towers). In the production of sulfuric acid using the nitrogen oxide process and in particular in Petersen's intensive tower process, it is always necessary to determine the conditions under which the operation of a system is carried out optimally and the measuring devices for checking the limit values mentioned above that they correspond to this optimal operation.
  • the inventive measures do not represent a "make-up" as an answer. indicates an increase in the NO content due to an insufficient NO content in the system. Rather, the increase in the NO content as it is poured in accordance with the invention shows above all one in the present system Decrease in the activity of the thin acid circulating in one of the sectors or in both sectors of the SO 2 processing zone.
  • the activity of the thin acid in the SO 2 processing zone is just sufficiently stimulated, to continue the conversion of SO 2 into SO 3 or sulfuric acid, surprisingly even if there is a lack of nitrogen oxides in the overall balance of the system.
  • the measures defined under (a) and (b) above are therefore not primarily intended to increase the NO x content of the system in such a way that a deficiency in the overall balance of NO x in the system is compensated for (make-up) , but as I said, to stimulate the activity of the thin acid circulating in the SO 2 processing zone each time a decrease in this activity is indicated by the measure (a) mentioned.
  • the nitric acid or the nitrogen oxides are brought into the liquid phase (the thin acid).
  • the liquid containing nitrogen-oxygen compound eg nitric acid
  • the liquid containing nitrogen-oxygen compound can either be mixed directly with the thin acid or mixed with the packing material. are introduced, in such a way that the reaction is preferably filled with packing apparatus diesor Zone sine mixing between added liquid and thin acid takes place.
  • Nitrous-oxygen compounds are those compounds which normally occur or are used in the nitrogen oxide process, that is to say NO, NO 2 , N 2 O 3 , nitrose or nitric acid and possibly also solid "chamber crystals". Nitrous acid is immediately oxidized to nitric acid in the nitrogen oxide process, or releases N 2 O 3 or forms nitric acid with nitric acid.
  • Gaseous contain substances which bound to oxygen, nitrogen, are thus NO- or NO 2 - and N 2 O 3 - containing gases, fliasige substances are in particular nitric acid itself or nitrous acid.
  • the amount of metered substance containing nitrogen-oxygen compound is preferably increased, to the extent that the NO content of the gas stream increases in or after the absorption zone.
  • the inflow rate of substance containing nitrogen-oxygen compound can also be kept constant as long as the NO content of the gas stream in or downstream of the absorption zone exceeds the limit content of NO.
  • the amount of nitrogen-oxygen compound added to the pretreatment part or the main part of the SO 2 processing zone in each corrective measure is only very small compared to the total amount of nitrous oxide circulating in the system.
  • the amount of substance added containing nitrogen-oxygen compound is increased to the extent that a steepness limit of the increase per unit time of the NO content in the gas stream in or downstream of the absorption zone is exceeded.
  • nitric acid as the nitrogen-oxygen compound.
  • the nitrogen-oxygen compound preferably consists of nitrogen oxides generated by ammonia combustion.
  • the substance mentioned can be formed in particular by absorption of nitrogen oxides in sulfuric acid.
  • the metering of the substance mentioned is preferably interrupted when the NO content of the gas stream downstream of the absorption zone drops below a predetermined value. d is lower than the aforementioned limit of NO; or the addition of said substance is reduced if the slope falls below a predetermined steepness limit value per unit of time of the NO content in the gas stream downstream of the absorption zone, the latter steepness limit value roughly corresponding to the steepness limit value according to (b).
  • At least a part of the substance introduced into the S0 2 processing zone can consist of nitrous sulfuric acid removed from the absorption zone, in particular the content of the nitroseha sulfuric acid removed from the absorption zone and metered into the SO 2 processing zone by the addition of nitrogen-oxygen compound Nitric acid can be increased.
  • a pretreatment zone through which the gas stream is passed before being introduced into the denitrification zone is connected upstream of the denitration zone and a part or the total amount of nitrogen-oxygen compound containing substance is added initiated this pre-treatment zone.
  • the portion of the stated amount of substance introduced into the pretreatment zone can be branched off from a nitrous sulfuric acid flowing from the absorption zone into the SO 2 processing zone.
  • At least part of the amount of substance to be introduced into the pretreatment zone can consist of gaseous nitrogen oxides produced by ammonia combustion, which are introduced into the gas stream before it enters the pretreatment zone.
  • the nitrogen-oxygen compound content of the nitrogen-oxygen compounds removed from the absorption zone and partly into the main area of the SO 2 processing zone and partly into the pretreatment zone can be increased by adding nitric acid.
  • the density of the acid emerging from the denitrification zone can be kept constant by adding thin acid or water, while the density of the thin acid flowing through the main area of the SO 2 processing zone in the circuit can be kept constant by adding acid from the pretreatment zone or water .
  • the feed line for taking up the nitrogen-oxygen compounds in the form of nitrous sulfuric acid can be connected to the bottom of a reaction apparatus of the nitrogen oxide absorption zone.
  • An introduction device for nitric acid can be provided in the last-mentioned feed line.
  • Such a preferred system according to the invention include a pretreatment zone upstream of the denitrification zone with a reactor and a sump, the line for Gas flow first into this pretreatment zone, preferably at its lower end and from the other end thereof, to one, preferably lower end of the denitrification zone and with a separate circuit line for thin acid leading from top to bottom through the pretreatment zone and a compensation line between the sumps of the pretreatment zone and the denitration zone is provided, and a branch line from said feed line to the upper end of the pretreatment zone can be provided.
  • An ammonia incineration plant can also be used with at least partial absorption of those developed therein Oxide in sulfuric acid serving column, and a transfer line can the bottom of the column with the upper end of a first in the gas flow direction the SO 2 processing zone for feeding Combine sulfuric acid in the latter zone.
  • Such a system can further comprise a pretreatment zone of the type described above upstream of the denitration zone, a feed line for nitrogen oxide-containing gases the upper end of the column of the ammonia combustion system with the part of the line introducing the gas stream into the preferably lower end of the pretreatment zone
  • the feed line mentioned under (g) can be connected to the nitrogen sump of the nitrogen oxide absorption zone between the uptake of the nitrogen-oxygen compound in the form of nitrogenous sulfuric acid and the bottom of a reaction apparatus, and a branch line can lead from the latter to the upper end of the column of the ammonia combustion plant.
  • This branch line from the supply line according to (g) with another sub-branch to the top of the zone.
  • the S0 2 processing zone follows the denitriding tower 2 in the gas flow direction with a first one and subsequent second tower 4 and on this the one and subsequent second tower 4 and on this the united in a single tower packed layers 5 and 6 ver nitrogen oxide absorption zone.
  • the SO 2 -containing exhaust gas to be treated is introduced via the inlet line 102 into the bottom end of the denitrification tower 2 and passes through Line 32 from the upper end of the tower 2 into the upper end of the tower 3 of the S0 2 processing zone, from the lower end of the tower 3 through the gas line 42 into the lower end of the tower 4 of the same zone and from the upper end of the tower 4 through the gas line 52 into the lower end of the tower with the filler layer 5 and then into the lower end of the filler layer 6 of the same tower and from the upper end of the latter filler layer via the exhaust line 72 with the aid of the blower (fan) 167 outside.
  • thin acid is circulated through the thin acid line 33 by means of a pump 35 via a heat exchanger 34 to the upper end of the packing layer of the tower 3 and collects at the bottom of this tower in the sump 31, from which the thin acid is pumped 45 through line 43 and exchanges heat to the upper end of the packed layer of tower 4 is pumped.
  • the thin acid cycle through the SO 2 processing zone is closed by pumping the thin acid out of the bottom of the tower 4 via line 33.
  • the density of the circulating acid in the SO 2 processing zone is measured by the density measuring device 233 at the outlet of the thin acid from the sump 41.
  • the density measuring device 233 can be used in a manner known per se. However, the corresponding valves and lines have been omitted from FIG. 1 for better clarity.
  • the vapor 51 of the common tower of the nitrogen oxide absorption zone is passed via line 54 with the aid of the pump 25, using the pump 25, into the heat exchanger 24 and after heating in the latter through the acid line 23 sprayed onto the upper end of the packing layer of the denitrification tower 2.
  • the denitrified acid collects in the sump 21 of this tower and is pumped through line 121 to heat exchanger 64 and from the latter through line 63 to the upper end of packed layer 6 of the tower of nitrogen oxide. Pumped up absorption zone.
  • the acid from the filler layer 6 flows directly onto the filler layer 5, while the gas to be treated from the filler layer 5 directly into the filler layer 6. In this case, therefore, no gas seal is required between the two filler layers.
  • Denitrated sulfuric acid with a content of 70-85% by weight of H 2 SO 4 can be branched off from line 63 via line 95 and valve 96 into the acid container 90 and can be removed from the system via P through line P.
  • the denitrification step is thus carried out in known catfish in the packed layer of the tower 2.
  • the process step of SO 2 processing takes place in the packed layers of towers 3 and 4 and the nitrogen oxide absorption step in the packed layers of the towers oxide absorption zone (towers 5 and 6), an acid between 70 and 85% by weight H 2 SO 4 (absorption acid) is used.
  • the concentration of the absorption acid is preferably 72 to 80% by weight of H 2 SO 4 .
  • nitrogen oxide is also released from the supplied acid in the denite zone in the method of the invention and reaches the absorption zone via the gas path, where the gas-form nitrogen oxide is absorbed by sulfuric acid. According to FIG.
  • this process takes place as follows: the nitrous-free absorption acid, which flows from the packed layer of the tower into the sump 21, is cooled in the cooler 64 and can be pumped through the pump 65 and the line 63 onto the packed ski 6 and then flows into. the packing layer 5 and from there i the sump 51 and then via line 54 to the pump 25 ur. Via the acid heater 24 and the line 23 back to the filling layer of the tower 2, where the nitrogen oxides which have been taken up in the layers of the towers 5 and 6 are released again.
  • the sumps of the towers are additionally pumped acid to the top of the same tower.
  • the corresponding devices are not shown to simplify the diagram; only those acid pipelines are given which bring about an acid exchange between different packing layers.
  • a container 80 is provided in which there is nitric acid a sulfuric acid with a high content of nitrose Nitric acid located.
  • the nitric acid is by the 83 passed into the container 80.
  • a line 82 provided with a valve 56 is connected to the sump 51 of the nitrogen oxide absorption zone and opens into the container 80. Nitrous acid-containing sulfuric acid can be discharged into the container 80 through the line 82.
  • the latter container is now according to the invention via the line 37, in which the pump 85 and the valve 46 are provided, connected to the upper end of the first tower 3 of the SO 2 processing zone.
  • An analyzer 285 continuously measures the NO Ge from the packed layer 6 of the tower, the zone outflowing gases. As soon as the NO content rises above a permissible value, or if the rise in the If NO occurs beyond a defined speed, the pump 85 is started, and sulfuric acid containing high nitric acid flows via the valve 46 and the line 37 into the packed layer of the tower 3.
  • the pump 85 is deactivated. Instead of switching the pump 85 on or off, a technically improved increase or decrease in the flow of strongly nitric acid-containing sulfuric acid can of course also be brought about.
  • the dead times in the control system are only a few minutes. Nevertheless, it is advisable to take appropriate control measures to prevent the concentrations from swinging back and forth. Such control measures are well known.
  • the analysis device 285 is located at the outlet of the packing layer of the absorption tower 6. It is also possible to adjust the nitrogen oxide content on the gases in the packing layer 5 of the between the packing layers 5 and 6 of the to eat. At these points, the nitrogen oxide content is of course correspondingly higher than at the outlet of the Zone. However, a measurement within the zone can be used as a controlled variable. It follows a reduction in dead time. It is also possible and, in special cases, expedient to have an NO measurement at the same time perform various points in the nitrogen oxide absorption zone.
  • liquid or gaseous St according to the invention which contain nitrogen-bound nitrogen as far as possible in the system.
  • This measure allows relatively small amounts of added nitrogenous subs to have a major influence on the NO content of the exhaust gases from the system.
  • the invention thus makes it possible to automate a nitrogen oxide-sulfuric acid system.
  • FIG. 2 realized form of the system according to the invention.
  • moist SO 2 -containing gases are brought into contact with thin acid in a pretreatment tower 1 connected to the denitration zone, the gases being drawn part of their water vapor content.
  • this function takes place in the packing layer 1.
  • the thin acid flowing out of the packing layer of tower 1 into the sump 71 of this tower is now pump 75 via line 73 the acid heating heat exchanger 74 and further the line 73 in the upper end of the tower 7, the layer represents an acid drainage zone
  • tower 1 of the pretreatment zone represents a pre-area of the SO 2 processing zone.
  • the amount of water absorbed by this acid during its circulation in the packed layer of the tower 1 is thus passed directly to the end of the system, i.e. led into the packed layer of the tower 7 and released there to the exhaust gas of the system supplied via line 72.
  • This dewatering measure by means of which the gas stream is dried in the pretreatment zone, means that less or no water vapor is transported further in the gas stream, thereby making it possible to maintain a sufficient acid concentration in the packing layer of the denitrification tower 2 and in the packing layers 5 and 6 of the nitrogen oxide absorption zone (e.g. 75% by weight H 2 SO 4 ). ;
  • the amount of water released can be controlled, whereby a desired concentration of the acid in the circuit via the packed layers of the towers 7 and 1
  • nitric acid or sulfuric acid or nitrous or nitric nitric acid-containing sulfuric acid is now conveyed from the container SO via the pump 85 through the line 37 to the valve 86 and further via the line 78 to the upper end of the packed layer of the tower and sprayed into the packed layer of the tower 1.
  • NO analyzer 285 opens the valve 86 and starts the pump 85.
  • This tower 1 which is provided with a packing layer, or a corresponding gas-liquid reaction apparatus of another type, which is sprinkled with thin acid and is located on the gas side at the beginning of the system, is thus charged with the total amount of the liquid or gaseous substances which contain nitrogen-bound nitrogen .
  • the packing layer of the tower 7 is connected at its lower end to the fan 167 via the conduit 72 and receives 6 dry exhaust gases from the absorption zone from the packing layer of the absorption tower. These exhaust gases remove water from the acid in the packed layer of the tower 7 and, together with the water vapor, reach the atmosphere via line 705.
  • the concentration of acids in certain circuits in order to regulate the NO: NO 2 ratio in the exhaust gas of the system or within the absorption zone of the nitrogen oxide-sulfuric acid system. This happened through Add water or add dilute acid to more concentrated acid.
  • changes in the acid concentrations for the purpose of regulating the system can be dispensed with. It is sufficient to keep the density of the acids at the outlet of the denitrification zone and in the circuit of the SO 2 processing zone constant. This known keeping constant is possible through automatic density control devices. As can be seen from FIG. 2, the density measuring device 221 is located on the drain line 121 from the sump 21.
  • This measuring device controls the valve 36 /, which causes some thin acid to flow into the packing layer of the denitrification tower via the pump 25 and the line 23 2 arrives.
  • the density meter controls the addition of thin acid in such a way that a constant acid concentration is maintained at the exit of the denitration zone, ie at the exit of the packing layer of the denitrification tower 2.
  • a compensation line 133 connects the sumps 71 and 31 and thus ensures a compensation of the acid level in both sumps.
  • the total amount of nitrogen-oxygen compound or of the substance containing it is not passed into the pre-area of the SO 2 processing zone, that is to say the pretreatment tower 1, but only part of the compound mentioned or substance, while the remaining part of the latter, as in the plant according to FIG. 1, is introduced into the upper end of the tower 3, that is to say into the main area, of the SO 2 processing zone.
  • the ratio of the partial quantities which on the one hand reach the preliminary area and on the other hand reach the main area of the SO 2 processing zone can be controlled by actuating the valves 46 and 86 accordingly.
  • the NO 2 content of the gases inside or after the absorption zone is also measured.
  • This measuring device is coupled to a control device of a known type (not shown) which is superior to the control described above, which is based on the measurement of the NO content.
  • the addition of substances which contain nitrogen-bound nitrogen is continuously reduced or reduced.
  • nitrous acid-containing sulfuric acid is removed from the absorption zone with the valve 56 open, and a corresponding amount of nitrous-free or low-nitrous acid is passed into the absorption zone.
  • the analyzer 255 continually measures the NO 2 concentration of the gases at the outlet of the packing layer 6. As soon as the NO 2 content rises above a predetermined level, or if the NO 2 concentration rises too rapidly, the pump 85 is shut down. As a result, the addition of strongly nitric acid-containing sulfuric acid from the container 80 into the packing layer of the tower 3 is interrupted. From lyser 255 also controls the pump 55.
  • the supply of / bound nitrogen is not in the form of nitric acid but in the form of gaseous nitrogen oxides, it is advantageous not to introduce the gaseous nitrogen oxides directly into the packed layers of towers 3 and 4 of the S0 2 processing zone. Rather, a quicker and more powerful effect is achieved if the nitrogen oxides are first dissolved in sulfuric acid and the nitrogen-containing sulfuric acid thus obtained is introduced into the SO2 processing zone.
  • 108 denotes a device for the catalytic oxidation of ammonia.
  • the nitrogen oxides formed are cooled in a heat exchanger 104 and then flow through a column 10 from bottom to top. That part of the nitrogen oxides which is not absorbed in the column 10 passes via a line 12 into the line 102 and thus into the main gas stream of the system.
  • Acid can be passed from line 78 via valve 106 into column 10, in which it is saturated with nitrogen oxides. This acid now passes through the sump 101 and the line 115 to the pump 116 and via line 117 and the valve 118 into the packed layer of the tower 3,
  • FIG. 5 an overall system is shown in FIG. 5, which combines all the features of the embodiments of the systems and permits them according to FIGS. 1 to 4 /, depending on the type and SO 2 content of the gases to be processed and depending on whether temporarily more Ammonia or more nitric acid is to be consumed, to perform optimally.
  • the following exemplary embodiment illustrates that of the method according to the invention in the system shown in FIGS. 3 and 5.
  • a controllable volume flow of this gas is introduced into the packing layer of the tower 1 of a plant according to FIG. 3.
  • the volume of the packed layers of towers 1 and 7 is 1 m 3 each.
  • the layers of towers 2 to 6 each contain 2.6 m 3 packing.
  • the total of all filling volumes is therefore 14 m 3 .
  • Polyethylene bodies according to DT-OS 24 16 955 are used as filling material.
  • the filling has a surface area of 2 3 c a. 300 m 2 / m 3 .
  • the acid circulation in the packed layers of towers 1 and 7 takes place as shown in FIG. 3 and amounts to 2 liters / Nm 3 of gas.
  • the layer of the tower 2 is sprinkled with 1 liter / Nm 3 of gas in the manner shown in FIG. 3.
  • the layers of towers 3 and 4 each have a sprinkling of 3 liters / Nm 3 of gas.
  • the sprinkling of layer 5 of the absorption tower is reinforced by a pump and a line, which are not shown in FIG. 3.
  • This pump conveys acid from the sump 51 onto the layer 5, so that together with the acid flow shown in FIG. 3, the filling results in a trickle of 4 liters / Nm 3 of gas.
  • the acid temperature at the outlet of heat exchange 74 and 24 is 63 ° C.
  • the acid temperature after the heat exchangers 34, 44, and 64 is between 30 and 40 ° C. Relative to a temperature of 15 ° C, the pumped acids have the following liter weight:
  • the nitrogen oxides absorbed in layers 5 and 6 of the absorption tower are passed with the acid via the sump 51 through the pump 25 via line 23 to the layer of the tower 2, in which these nitrogen oxides are reacted with the SO 2 as NO in the Gas flow arrive, which leaves the layer of the tower 2 through line 32.
  • the SO. Processing in the layers of towers 3 and 4 is all the better the more nitrogen oxides are contained in the gas stream.
  • nitrous acid per Nm 3 of gas is passed into the layer of tower 2 via line 23.
  • nitric acid which was fed to the container via line 83, is passed from the container 80 by means of the pump 85 via the valve 46 through the line 37 to the layer of the tower 3.
  • the nitrogen oxides released in the layer of this tower 3 and the subsequent tower 4 pass through the gas line 42, 52 into the layer 5 of the absorption tower and are taken up there by the sulfuric acid and trickle into the sump 51.
  • an exhaust gas from the overall system in line 705 is obtained, which contains 50 to 100 ppm NO and 200 to Contains 300 ppm N0 2 . If instead of 400 Nm 3 / h a gas quantity of 500 Nm 3 / h is fed into the system, or if the SO 2 content in the inlet gas increases while the gas quantity remains the same, the system can no longer process the S0 2 completely and SOA can be used 2 into the absorption zone, which increases the NO content of the system's exhaust gases.
  • the invention In order to be able to process the increased amount of SO 2 without a large loss of nitrogen oxide, the invention must - provided that were not used - the nitrous content of the acid which is passed into the layer of the tower 2 increased and / or the amount of acid which is in the layer of the 2 is increased.
  • the nitrous content in the sump 51 With the normal sprinkling of the layer of tower 2 of 1 liter / Nm 3 of gas, the nitrous content in the sump 51 must be increased to approximately 3% by weight of HNO 3 , 500 Nm 3 / h of gas must be processed.
  • both an increase and a decrease in the SO 2 concentration of the inlet gases and also a change in the volume flow of the SO 2 -containing gases can be compensated for without a greater loss of nitrogen oxide via the exhaust gases.
  • An increase in the S0 2 content in the gas to be treated causes the NO content of the gases measured continuously in the analyzer 285 after the absorption zone to exceed the normal value of 100 ppm to, for example, 150 ppm.
  • An automatic control device then starts the pump 85, whereby a sulfuric acid, which contains 20% by weight of nitric acid, is passed from the container 80 through the lines 78 and 37, respectively, into the packed layers of the towers 1 and 3.
  • the valves 86 and 46 are regulated so that 0.4 liters per minute flows to the layer of tower 1 and 0.6 liters per minute to the layer of tower 3. After only two minutes, the NO content at the exit of the absorption zone drops below 100 ppm and the pump 85 is deactivated.
  • the nitric acid added to the thin acid in the two circuits through towers 1 and 3 consumes after about 15 minutes and is released in the form of gaseous nitrogen oxides. These nitrogen oxides are taken up by the acid in the absorption zone, as a result of which the nitrous content of the acid in the sump 51 increases.
  • the increase in nitrose is not yet sufficient to bring about a reaction in the layer of the denitrification tower which is adapted to the increased quantity of SO 2 in the gas stream.
  • the NO content of the exhaust gases rises again above 150 ppm, while the NO 2 content drops from a maximum of 250 ppm below 150 ppm.
  • the analyzer 285 switches the pump 85 on again and again the NO content of the gases after the absorption zone drops below 100 ppm after only two minutes, as a result of which the pump 85 is switched off.
  • This process of switching the pump 85 on and off is repeated until the nitrous content in the sump 51 has adapted to the increased amount of SO 2 in the gas stream entering through line 102, which must be processed in the system.
  • the distance between two switching periods becomes longer the closer the nitrous content in the sump 51 approaches the value necessary for SO 2 processing.
  • the amount of gas that has to be processed in the system becomes smaller or the concentration of S0 2 in the gas to be treated drops, then the NO 2 content of the gases increases downstream of the absorption zone and the NO content falls far below 100 ppm from.
  • the N0 2 content of the exhaust gases in the absorption zone is continuously measured by the analyzer 255. If the N0 2 content per minute increases by more than 30 ppm per minute, and / or if the NO 2 content reaches over 200 ppm, an automatic control means. device (not shown) the pump 85 stopped, provided that it was in operation at that time.
  • an automatic control device opens the valve 56 and switches on the pump 55.
  • nitrous sulfuric acid flows into the container 80, while from the container 90 nitrous-free sulfuric acid reaches the packing layer 5 by means of the pump 55 via the line 53.
  • the amount of acid added and drawn off is 0.3 liters per / Nm 3 of gas.
  • the automatic control device closes the valve 56 and puts the pump 55 out of operation.
  • sulfuric acid is produced, which flows out of the container 90 as production via the drain line (P).
  • the control devices described make it possible to keep the N x O y content (sum of the NO and NO 2 content) of the exhaust gases of the system constantly below 400 ppm, even if the amount of gas to be processed or the SO 2 concentration is subject to frequent fluctuations in the range of ⁇ 70% of the daily average.
  • the liter weight (or density) of the acid circuits is regulated as follows:
  • the liter weight of the circuit over the packing layers of the towers 1 and 7 is kept at 1.5 kg / liter by regulating the heat supply in the heat exchanger 14. Increased heat supply increases the water release in the packing layer of the tower 7 and therefore increases the liter weight.
  • the liter weight in the acid cycle of the packed layers of the towers and 4 of the SO 2 processing zone is kept at 1.56 kg / liter by the controlled addition of acid from the sump 71.
  • the corresponding lines and valves are not shown in Fig. 3.
  • the liter weight at the outlet of the denitrification tower 2 is kept at 1.67 kg / liter by controlled addition of thin acid from the sump 31 onto the packed layer of the tower 2.
  • Analyzers as used in plants according to the invention are well known. For example, we manufacture them from Thermo Electron Corporation, Waltham, Mass., USA and sell them as "NO x chemiluminescent source analyzer for automative emission” or as “NO-NO x chemiluminescent analyzer", eg "Model 44".
  • a circuit to be used for control is, for example, in the article "Automation Control Technology” in Meyer. Handbook on technology, Biographical Institute Mannheim General Publishing House 1971, pages 729 - 736. If, for example in Fig. 1 of this article, a NO or N0 2 analyzer of the type described above is used instead of the thermocouple, the valve shown is controlled via the electrical transmitter MU and controller R. A more detailed representation of the switching part from the electrical transmitter MU to a valve or a pump is illustrated in the left half of Fig. 8 of the same article.

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  • Analytical Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Treating Waste Gases (AREA)
  • Gas Separation By Absorption (AREA)
EP78100389A 1977-07-21 1978-07-13 Procédé pour enlever le gaz sulfureux d'un courant gazeux et installation pour la mise en oeuvre du procédé Expired EP0000515B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH906377 1977-07-21
CH9063/77 1977-07-21

Publications (2)

Publication Number Publication Date
EP0000515A1 true EP0000515A1 (fr) 1979-02-07
EP0000515B1 EP0000515B1 (fr) 1981-12-02

Family

ID=4347916

Family Applications (1)

Application Number Title Priority Date Filing Date
EP78100389A Expired EP0000515B1 (fr) 1977-07-21 1978-07-13 Procédé pour enlever le gaz sulfureux d'un courant gazeux et installation pour la mise en oeuvre du procédé

Country Status (16)

Country Link
US (1) US4242321A (fr)
EP (1) EP0000515B1 (fr)
JP (1) JPS5452672A (fr)
AT (1) AT372619B (fr)
AU (1) AU528394B2 (fr)
BR (1) BR7804687A (fr)
CA (1) CA1103899A (fr)
DD (1) DD137916A5 (fr)
DE (1) DE2830214A1 (fr)
ES (1) ES471907A1 (fr)
FI (1) FI65978C (fr)
IN (1) IN149347B (fr)
IT (1) IT7850388A0 (fr)
PL (1) PL111169B2 (fr)
SU (1) SU980611A3 (fr)
ZA (1) ZA784133B (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5456891A (en) * 1991-08-16 1995-10-10 Nymic Anstalt Process for the purification of contaminated exhaust gases from incineration plants

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1900701C3 (de) * 1969-01-08 1980-08-07 Hauni-Werke Koerber & Co Kg, 2050 Hamburg Verfahren und Anordnung zum Steuern des Anfahrens und/oder Anhaltens einer Maschine zum Herstellen von Zigaretten oder anderen stabförmigen Tabakartikeln
US4400362A (en) * 1981-11-04 1983-08-23 Lerner Bernard J Removal of nitrogen oxides from gas
EP0174907A3 (fr) * 1984-08-13 1989-10-25 Ciba-Geigy Ag Procédé d'élimination d'oxydes d'azote et de soufre des gaz d'échappement
US4716066A (en) * 1985-04-16 1987-12-29 Wam-Plast Ag Filling body of acid-resistant synthetic plastics material

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BE501481A (fr) *
SU172728A1 (ru) * К. В. Нейперт, А. П. Громов , В. М. Проценхо Способ регулирования состава окислов азота
DE2510294A1 (de) * 1975-03-10 1976-09-23 Ciba Geigy Ag Verfahren zum abtrennen von so tief 2 aus gasstroemen unter gewinnung von schwefelsaeure nach dem stickoxid-verfahren

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US1486757A (en) * 1923-05-31 1924-03-11 Jensen Ernst Method of automatic regulation of the supply of oxidizing agents, such as nitric acidnitrate solution, or others in the manufacture of sulphuric acid
US1889973A (en) * 1924-06-06 1932-12-06 Silica Gel Corp Chamber process of manufacturing sulphuric acid
US1800786A (en) * 1926-08-12 1931-04-14 Andrew M Fairlie Ammonia oxidation equipment and the use thereof for the manufacture of sulphuric acid
GB270988A (en) * 1926-10-12 1927-05-19 Hugo Petersen Improvements in and relating to the manufacture of sulphuric acid
GB363327A (en) * 1929-06-11 1931-12-11 Industrikemiska Ab Improvements in and relating to the production of sulphuric acid
NL37191C (fr) * 1931-11-12
FR1072033A (fr) * 1953-01-08 1954-09-07 Saint Gobain Procédé et appareil pour le contrôle du fonctionnement des installstions de fabrication de l'acide sulfurique
DE1140909B (de) * 1959-10-06 1962-12-13 Ruhr Schwefelsaeure Ges Mit Be Verfahren zur Steuerung der Oxydations-geschwindigkeit des Schwefeldioxyds und der Stickoxyde in einem System zur Herstellung von Schwefelsaeure nach der Stickoxydmethode

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE501481A (fr) *
SU172728A1 (ru) * К. В. Нейперт, А. П. Громов , В. М. Проценхо Способ регулирования состава окислов азота
DE2510294A1 (de) * 1975-03-10 1976-09-23 Ciba Geigy Ag Verfahren zum abtrennen von so tief 2 aus gasstroemen unter gewinnung von schwefelsaeure nach dem stickoxid-verfahren

Non-Patent Citations (1)

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Title
CHEMISCHES ZENTRALBLATT, Jrg.127, 1956, no. 51. A.I. APACHOW et al.: "Automatische Regulierung der Vorbereitung der Stickstoffoxyde f}r die Absorption in der Turmschwefels{ureindustrie", Zusammenfassung Seite 14151; & CHEM. IND. 1955, nr. 8, 27-29 Dez. (in russischer Sprache). *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5456891A (en) * 1991-08-16 1995-10-10 Nymic Anstalt Process for the purification of contaminated exhaust gases from incineration plants

Also Published As

Publication number Publication date
DE2830214A1 (de) 1979-02-08
ES471907A1 (es) 1979-02-01
ZA784133B (en) 1979-07-25
AU528394B2 (en) 1983-04-28
BR7804687A (pt) 1979-04-17
AT372619B (de) 1983-10-25
SU980611A3 (ru) 1982-12-07
DD137916A5 (de) 1979-10-03
ATA526178A (de) 1983-03-15
PL208579A1 (pl) 1979-04-23
CA1103899A (fr) 1981-06-30
FI65978B (fi) 1984-04-30
AU3820078A (en) 1980-01-24
FI782255A (fi) 1979-01-22
US4242321A (en) 1980-12-30
IN149347B (fr) 1981-10-31
IT7850388A0 (it) 1978-07-20
FI65978C (fi) 1984-08-10
EP0000515B1 (fr) 1981-12-02
PL111169B2 (en) 1980-08-30
DE2830214C2 (fr) 1989-03-16
JPS5452672A (en) 1979-04-25
JPS6332723B2 (fr) 1988-07-01

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