EP0000515B1 - Verfahren zum Abtrennen von Schwefeldioxyd, aus einem Gasstrom und Anlage zur Durchführung des Verfahrens - Google Patents

Verfahren zum Abtrennen von Schwefeldioxyd, aus einem Gasstrom und Anlage zur Durchführung des Verfahrens Download PDF

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EP0000515B1
EP0000515B1 EP78100389A EP78100389A EP0000515B1 EP 0000515 B1 EP0000515 B1 EP 0000515B1 EP 78100389 A EP78100389 A EP 78100389A EP 78100389 A EP78100389 A EP 78100389A EP 0000515 B1 EP0000515 B1 EP 0000515B1
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zone
acid
nitrogen
gas
content
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French (fr)
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EP0000515A1 (de
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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

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  • the invention relates to a process for separating S0 2 from a gas stream which contains it at least temporarily in a concentration which is inadmissibly high for discharging into the ambient air with the production of sulfuric acid by the nitrogen oxide process, in the latter the gas containing SO 2 first being a denitrification zone or a gas dewatering zone serving pretreatment zone and then the denitrification zone, then the main area of the SO 2 processing zone, consisting of at least one full-body tower and then a nitrogen oxide absorption zone, wherein it flows through the relevant area of this zone in at least one of the two areas of the SO 2 processing zone circulating dilute acid of concentrations below 70% by weight (55 ° Be) H 2 SO 4 is brought into contact, while in the absorption zone the nitrogen oxides released in the denitrification zone are taken up by sulfuric acid and nitrous acid from the absorption zone t a content of 70 to 85 wt .-% (55 to 63.5 ° Be) H 2 S0 4 is removed and transferred to the denitr
  • nitric acid or concentrated nitrous gases such as those resulting from the catalytic combustion of ammonia (make-up).
  • nitric acid or concentrated nitrous gases such as those resulting from the catalytic combustion of ammonia (make-up).
  • the addition of nitric acid or the addition of strong nitrous gases is carried out either at the top of the denitrification tower (DE-A-26 09 505) or in front of a production tower which is covered with acid of more than 70% by weight H 2 SO 4 is sprinkled.
  • the need for the addition of nitric acid or strong nitrous gases can be seen in known nitrogen oxide-sulfuric acid systems above all by the nitrous content of the acid flowing out of the absorption zone into the bottom of this zone. It has the highest nitrous content of any acid in the system.
  • 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 to say the control of the ratio NO: N0 2 in the exhaust gases, is carried out in most cases in known nitrogen oxide-sulfuric acid plants by adding more or less water into the acid cycle through the denitrification zone and the nitrogen oxide absorption zone.
  • the difference between the temperatures of the gases at the inlet and at the outlet of the series of reaction chambers of the SO 2 processing zone provides what difference according to the US-A- 1 486 757 (Jensen) from 1924 to determine nitrogen oxide losses and to compensate for them by introducing nitric acid into the first S0 2 processing chamber, for example, is not a reliable criterion, since this temperature difference is not only due to the more or less correct functioning of the System but also depends on the daily fluctuations in the outside temperature. Otherwise, this method would also not be applicable to intensive processes for the production of sulfuric acid, such as, for example, that of DE-A-26 09 505 and the process of the present invention, since the temperature differences occurring in this case would be far too small to control the system.
  • DE-C-1 140 909 (Ruhr-Schwefelkla GmbH) describes an adjustment of the ratio of NO: N0 2 and the content of NO + N0 2 in the gas phase by 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 patent is a strong acid with a content of 80% by weight H Z S0 4 , and not a thin acid of less than 70% by weight H 2 SO 4 , as in the SO 2 processing zone of DE-A-26 09 505 circulates.
  • the invention further aims to achieve an improved, very rapid adaptation of the NO: N0 2 ratio in the exhaust gas emitted from the system, so that this exhaust gas leaves the system practically without formation of a yellow flag caused by the presence of N0 2 in the exhaust gas 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 explained 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-A-25 10 294 and 26 09 505.
  • the specific amount of the NO limit value or the slope limit value cannot be specified in general, but depends on the system and in particular on the size of the various reaction apparatuses (towers).
  • the activity of the thin acid in the SO 2 processing zone is just sufficiently stimulated to continue the conversion of SO 2 to S0 3 or sulfuric acid, and surprisingly even then, if there is a deficiency of nitrogen oxides in the overall balance of the system.
  • This makes it possible to operate the system practically at a minimum level of NO x , thus avoiding any excess of NO.
  • the stimulation mentioned is far greater than was to be expected from the slight increase in the NO x content in the system, as occurs as a result of measures (a) and (b).
  • 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 for example nitric acid
  • Nitrous-oxygen compounds are those compounds that normally occur or are used in the nitrogen oxide process, ie NO, NO 2 , N 2 O 3 , nitrous 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 0 3 or forms nitric acid with nitric acid.
  • Gaseous substances which contain nitrogen-bound nitrogen are therefore NO- or N0 2 - or N 2 0 3 -containing gases, liquid substances are in particular nitric acid itself or nitrous sulfuric 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 with each corrective measure is compared to the total amount of nitrous oxide circulating in the system only very small.
  • the amount of substance containing nitrogen-oxygen compound added is increased to the extent that a steepness limit value 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 is preferably used 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 said substance is preferably interrupted when the NO content of the gas stream downstream or absorption zone drops below a predetermined value which is lower than the aforementioned limit NO content; or the addition of said substance is reduced if the drop below a predetermined steepness limit value per unit time of 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 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 nitrogen-oxygen compound content of the nitrous sulfuric acid removed from the absorption zone and metered into the S0 2 processing zone by adding 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 compound in the form of nitrous sulfuric acid can be connected to the bottom of a reactor of the nitrogen oxide absorption zone.
  • An introduction device for nitric acid can be provided in the last-mentioned feed line.
  • Such a preferred plant according to the invention may comprise a pretreatment zone with reaction apparatus and sump upstream of the denitration zone, the line for the gas stream first leading into this treatment zone, preferably at the lower end and from the other end thereof, to one, preferably lower end of the denitration zone, and one separate, leading through the pretreatment zone from top to bottom circulation line for thin acid and a compensating line between the sumps of the pretreatment zone and the denitrification zone is provided, and a branch line from said feed line to the upper end of the pretreatment zone can be provided.
  • An ammonia combustion plant can also be provided with a column which serves at least partially to absorb the nitrogen oxides developed therein in sulfuric acid, and a transfer line can connect the base of the column with one, preferably the upper end of a first apparatus in the gas flow direction of the SO 2 processing zone for the purpose of supplying sulfuric acid containing nitrogen oxide connect to the latter zone.
  • such a system can comprise a pretreatment zone of the type described above upstream of the denitrification zone, a feed line for nitrogen oxide-containing gases connecting the upper end of the column of the ammonia combustion system to 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 bottom of a reactor of the nitrogen oxide absorption zone for the purpose of taking up the nitrogen-oxygen compound in the form of nitrous sulfuric acid, 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 feed line according to (g) can be connected to the upper end of the pretreatment zone with a further sub-branch.
  • the denitrification tower 2 is followed in the gas flow direction by the S0 2 processing zone with a first tower 3 and subsequent second tower 4, and by this the packing layers 5 and 6 of the nitrogen oxide absorption zone combined in a single tower.
  • the SO 2 -containing exhaust gas to be treated is introduced via the inlet line 102 into the lower end of the denitrification tower 2 and passes via 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 packing layer 5 and then into the lower end of the packing layer of the same tower and from the upper end of the latter packing layer via the exhaust line 72 with the aid of the blower (fan) 167 to the outside.
  • thin acid is circulated in the system shown in FIG. 1 through the thin acid line 33 by means of a pump 35 via a heat exchanger 34 to the upper end of the packed layer of the tower 3 and collects at the lower end of this tower in Sump 31 from which the thin acid is pumped up by means of the pump 45 through the line 43 and the heat exchanger 44 to the upper end of the packed layer of the tower 4.
  • the thin acid cycle through the S0 2 processing zone is closed by pumping off the thin acid from the sump 41 of the tower 4 via line 33.
  • Sulfuric acid of about 65% by weight H 2 SO 4 is preferably used as the thin acid in this circuit.
  • 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.
  • Either water or acid can be used in a manner known per se to regulate the density.
  • the corresponding valves and lines have been omitted from FIG. 1 for the sake of a better overview.
  • nitrous sulfuric acid is fed via line 54 with 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 packing layer 6 flows directly onto the packing layer 5, while the gas to be treated passes from the packing layer 5 directly into the packing layer. In this case, no gas seal is required between the two packing 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 the removal line at P.
  • the denitrification step therefore takes place in a known manner in the packed layer of the tower 2.
  • the S0 2 processing step takes place in the packed layers of towers 3 and 4 and the nitrogen oxide absorption step in the packed layers of towers 5 and 6 S0 2 processing zone (towers 3 and 4) a sulfuric acid of less than 70 wt .-% H 2 SO 4 is used (thin acid).
  • a sulfuric acid of less than 70 wt .-% H 2 SO 4 is used (thin acid).
  • 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 denitration zone in the method of the invention and passes via the gas path into the absorption zone, where the gaseous nitrogen oxide is absorbed by sulfuric acid.
  • this process takes place as follows: the nitrous-free absorption acid, which flows from the packed layer of the tower 2 into the sump 21, is cooled in the cooler 64 and reaches the packed layer via the pump 65 and the line 63 and then flows into the Packing layer and from there into the sump 51 and then via the line 54 to the pump 25 and via the acid heater 24 and line 23 back to the packing layer of the tower 2, where the nitrogen oxides which have been taken up in the layers of the towers 5 and 6, be given back to the gas.
  • acid is additionally pumped from the sumps of the towers to the top of the same tower in order to increase the mass exchange between the gas and the acid.
  • the corresponding devices are not shown to simplify the scheme; only those acid lines are shown in the diagram which have an acid bring about exchange between different packing layers.
  • a container 80 is now provided in the system according to FIG. 1, in which there is nitric acid or a sulfuric acid with a high content of nitrous and / or nitric acid.
  • the nitric acid is passed through line 83 into 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 drained through line 82 into container 80.
  • the latter container is now connected according to the invention via line 37, in which the pump 85 and the valve 46 are provided, to the upper end of the first tower 3 of the SO 2 processing zone.
  • An analyzer 285 continuously measures the NO content of the gases flowing out of the packed layer of the tower of the absorption zone. As soon as the NO content rises above a permissible value, or if the concentration of NO rises above a predetermined speed, the pump 85 is started and strongly nitric acid-containing sulfuric acid flows via the valve 46 and the line 37 into the packed layer of the Tower 3.
  • pump 85 is deactivated. Instead of switching the pump 85 on or off, it is of course also possible to bring about an increase or decrease in the flow of strongly nitric acid-containing sulfuric acid, which is improved in terms of control technology.
  • 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 measure the nitrogen oxide content at the entry of the gases into the packing layer 5 of the absorption tower or between the packing layers 5 and 6 of the absorption zone. At these points, the nitrogen oxide content is of course correspondingly higher than at the exit of the absorption zone. However, a measurement within the absorption zone can also be used as a controlled variable. The dead time is then reduced. It is also possible, and in particular cases expedient, to carry out an NO measurement simultaneously at different points in the nitrogen oxide absorption zone.
  • the acid can be additionally heated in the heat exchanger 74 so that the water release of the acid in the packed layer of the tower 7 is increased.
  • the tower 1 of the pretreatment zone shown in FIG. 2 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 S0 4 ).
  • the amount of water dispensed can be controlled, as a result of which a desired concentration of the acid in the circuit can be set via the packed layers of the towers 7 and 1.
  • a desired concentration of the acid in the circuit can be set via the packed layers of the towers 7 and 1.
  • nitric acid or sulfuric acid or nitrous or nitric acid nitric acid is now conveyed from the container 80 via the pump 85 through the line 37 to the valve 86 and further via line 78 to the upper end of the packed layer of the tower and sprayed into the packed layer of the tower 1 when that NO analyzer 285 opens valve 86 and activates pump 85.
  • This preferred embodiment of the invention as shown in the system according to FIG., therefore uses tower 1 sprinkled with thin acid, which is connected on the gas side in front of the denitrification zone, for regulating the entire system.
  • 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 via line 72 to the fan 167 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 density measuring device 221 is located on the drain line 121 from the sump 21.
  • This measuring device controls the valve 36, so that some thin acid is introduced into the packed layer of the denitrification tower 2 via the pump 25 and the line 23 reached.
  • the density measuring device controls the addition of thin acid in such a way that a constant acid concentration is maintained at the outlet of the denitration zone, ie at the outlet 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 substance containing it is not passed into the pre-area of the SO 2 processing zone, that is to say the pre-treatment tower 1, but only part of the compound mentioned or substance, while the remaining part of the latter is introduced into the upper end of the tower 3, that is to say into the main area of the SO 2 processing zone, as in the system according to FIG. 1.
  • 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 Z processing zone can be controlled by corresponding actuation of valves 46 and 86.
  • the NO Z content of the gases is measured inside or after the absorption zone.
  • 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 containing nitrogen-bound nitrogen is interrupted or reduced.
  • nitrous acid-containing sulfuric acid is removed from the absorption zone by opening valve 56 beyond the normal level and a corresponding amount of nitrous-free or low-nitrous acid is passed into the absorption zone.
  • the analyzer 255 continuously measures the N0 2 concentration of the gases at the outlet of the packing layer 6. As soon as the NO z content rises above a fixed value, or if the NO 2 concentration rises too rapidly, the pump 85 is shut down. This will add strong nitric acid containing sulfuric acid from the container 80 interrupted in the packed layer of the tower 3.
  • the pump 55 is also controlled by the analyzer 255.
  • nitrous acid flows into the tank 80 and from the tank 90 nitrous-free acid via line 53 to the packing layer of the Absorption tower is directed.
  • the nitrous-free absorption acid flushes the nitrous acid from the packing layer 5 into the sump 51 and via the line 82 into the container 80.
  • the supply of nitrogen-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 SO 2 processing zone. Rather, a faster and more powerful effect is achieved if the nitrogen oxides are first dissolved in sulfuric acid and the nitrogen-containing sulfuric acid obtained in this way is introduced into the SO z 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 plant.
  • 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.
  • FIGS 4 which shows all the features of the embodiments of the systems according to FIGS 4 combines and permits, depending on the type and S0 2 content of the gases to be processed and depending on whether more ammonia or more nitric acid is to be used temporarily, the treatment of the SO 2 -containing in any of the sub-systems shown in the previous figures To carry out exhaust gases in accordance with the method according to the invention in an economically optimal manner.
  • the following exemplary embodiment illustrates the implementation of the method according to the invention in the system shown in FIGS. 3 and 5.
  • the rest is nitrogen.
  • 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 15 m 3 .
  • Polyethylene bodies according to DE-A-24 16 955 are used as filling material.
  • the filling has a surface area of approx. 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 gas.
  • the sprinkling of layer 5 of the absorption tower is increased by a pump and a line, which are not shown in FIG. 3.
  • This pump conveys acid from the sump 51 to the layer 5, so that together with the acid flow shown in FIG. 3, the filling is sprinkled with 4 liters / Nm 3 of gas.
  • the acid temperature at the outlet of heat exchangers 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 S0 2 processing in the layers of towers 3 and 4 is the better, the more nitrogen oxides are contained in the gas stream.
  • nitrous acid is passed into the layer of the tower 2 per Nm 3 of gas.
  • the higher the nitrous content of the acid the more SO 2 -containing gas can be processed in the system. If the acid's nitrous content is too high, however, the nitrogen oxide content of the system's exhaust gases increases.
  • 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 300 contains 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 S0 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 S0 is reached 2 into the absorption zone, which increases the NO content of the system's exhaust gases.
  • the nitrous content of the acid which is passed into the layer of tower 2 must be increased and / or the amount of acid which is in - unless the measures according to the invention are used the layer of the tower 2 is directed, increased.
  • the nitrous content in the sump 51 must be increased to approx. 3% by weight of HN0 3 if 500 Nm 3 / h of gas have to 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 an increase in the NO content of the gases measured continuously in the analyzer 285 after the absorption zone above the normal value of 100 ppm to, for example, 150 ppm.
  • An automatic control device then activates the pump 85, as a result of which a sulfuric acid, which contains 20% by weight of nitric acid, is passed from the container 80 through the lines 78 and 37 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 has to 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 required for S0 2 processing.
  • the N0 2 content of the gases increases downstream of the absorption zone and the NO content falls far below 100 ppm from.
  • the analyzer 255 continuously measures the NO 2 content of the exhaust gases in the absorption zone. If the NO 2 content per minute increases by more than 30 ppm per minute and / or if the NO 2 content reaches over 200 ppm, the pump 85 is stopped by an automatic control device (not shown), if the same at this time was in operation.
  • the acid of the container 80 is reintroduced into the system during periods of entry of gases with a high SO 2 content into the system.
  • sulfuric acid is produced, which flows out of the container 90 as production via the drain line (P).
  • Analyzers as used in plants according to the invention are well known. We are, for example, manufactured by Thermo Electron Corporation, Waltham, Mass., USA and marketed as "NO x chemiluminescent source analyzer for automat i ve emission” or as “NO-NO x chemiluminescent analyzer", eg "Model 44".
  • a circuit to be used for control is described, for example, in the article "Automation Control Technology in Meyers Handbook on Technology, Blographisches Institut Mannheim, Bushe Verlag 1971, pages 729-736. If, for example in Fig. 1 of this article, a NO or NO 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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EP78100389A 1977-07-21 1978-07-13 Verfahren zum Abtrennen von Schwefeldioxyd, aus einem Gasstrom und Anlage zur Durchführung des Verfahrens Expired EP0000515B1 (de)

Applications Claiming Priority (2)

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

Publications (2)

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EP0000515A1 EP0000515A1 (de) 1979-02-07
EP0000515B1 true EP0000515B1 (de) 1981-12-02

Family

ID=4347916

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EP78100389A Expired EP0000515B1 (de) 1977-07-21 1978-07-13 Verfahren zum Abtrennen von Schwefeldioxyd, aus einem Gasstrom und Anlage zur Durchführung des Verfahrens

Country Status (16)

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

Families Citing this family (5)

* 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 (de) * 1984-08-13 1989-10-25 Ciba-Geigy Ag Verfahren zur Entfernung von Stickstoff- und Schwefeloxiden aus Abgasen
US4716066A (en) * 1985-04-16 1987-12-29 Wam-Plast Ag Filling body of acid-resistant synthetic plastics material
DE4127075A1 (de) * 1991-08-16 1993-02-18 Nymic Anstalt Verfahren zum reinigen von belasteten abgasen von verbrennungsanlagen

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE501481A (fi) *
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 (fi) * 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
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

Also Published As

Publication number Publication date
ES471907A1 (es) 1979-02-01
DE2830214A1 (de) 1979-02-08
ATA526178A (de) 1983-03-15
IN149347B (fi) 1981-10-31
JPS5452672A (en) 1979-04-25
ZA784133B (en) 1979-07-25
PL208579A1 (pl) 1979-04-23
US4242321A (en) 1980-12-30
FI782255A (fi) 1979-01-22
PL111169B2 (en) 1980-08-30
JPS6332723B2 (fi) 1988-07-01
AU3820078A (en) 1980-01-24
EP0000515A1 (de) 1979-02-07
FI65978C (fi) 1984-08-10
AT372619B (de) 1983-10-25
CA1103899A (en) 1981-06-30
AU528394B2 (en) 1983-04-28
FI65978B (fi) 1984-04-30
SU980611A3 (ru) 1982-12-07
DE2830214C2 (fi) 1989-03-16
BR7804687A (pt) 1979-04-17
IT7850388A0 (it) 1978-07-20
DD137916A5 (de) 1979-10-03

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