JPS59173746A - Electrochemical gas analyzer for content of gas, particularly, so2 in flue gas - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention comprises a measuring vessel having a measuring electrode indicating a negative flow of the gas to be measured in an equal electrolyte and an incorrigible counter electrode, the electrolyte being dissolved in The electrolyte containing the gas is made to flow through the measuring gas conduit as a circulating flow which discharges through an intermediate chamber between the measuring electrolyte and the counter electrode, and is guided in the circulating flow and constantly regenerated and dissolved in the electrolyte. The invention relates to an electrochemical gas analyzer for the SO content in gases, in particular flue gases, in such a way that the SO content in gases, in particular flue gases, is treated with air in the presence of activated carbon outside the tank and disposed of.

The regulation of the 5O2 content in waste gases is currently a particularly important measurement technology issue. All previously used known measuring instruments based on the color principle (infrared, thermal conductivity, heat radiation, etc.) are either too expensive or can only be used in very limited measuring fields.

For this reason, an electrochemical sludge analyzer of the above type has been developed by the applicant (see European Patent Application No. 0059841). This gas analyzer is reasonably priced and applicable over a wide concentration range. In this gas analyzer, an electrolytic solution is dropped into a measurement tank, and the consumed electrolytic solution is drawn out. This electrolyte is optionally treated outside the tank with air in the presence of activated carbon to remove the S02 dissolved therein, and then returned to the tank via a circulation system. A copper sulfate solution of sulfuric acid is used as the electrolyte.

The higher the detection sensitivity of such a device, the higher the detection sensitivity of such a device, since the measurement effect depends on the 502- concentration in the electrolyte, which increases cumulatively over the contact time until an equilibrium value is reached.
Longer and longer electrolyte saturation times are selected. Therefore, in such a device, approximately Q.01 per minute is normally used.
~0.1 of electrolyte is present in the cell (see German Patent No. 1.091.776). Such electrolyte exchanges generally do not require considerations for thinning, regeneration and recirculation, and are so slight that such considerations become necessary only when the concentration of copper salts in the electrolyte becomes significant. The removal of /S02 by oxidation with oxygen in the presence of the required activated carbon is usually carried out by suspending the activated carbon in an electrolyte and introducing air through this suspension.

However, in practice, unfortunately, the stability and reproducibility of the measurement results and the almost linear dependence of the measurement results on the 5O2 content leave room for improvement over the entire measurement range. I understand. This problem can be solved, for example, by the temperature constant proposed in the above-mentioned German Patent Specification. It cannot be solved even by 144 composition.

However, when the electrolyte exchange is significantly increased so as to result in a modest but useful reduction of the measurable measurement signal in the measuring tank, the working style in the tank is significantly improved and the measured values for the 5O2 content are significantly improved. It is found that the linearity of the dependence of is improved and the response speed is increased. In this case care is taken that an active exchange of the electrolyte takes place in the cell, such that at least about 50 parts of the electrolyte 'fl-iL are exchanged in the cell per minute. Since the signal height decreases as the electrolyte exchange progresses, an upper limit is also placed on the electrolyte exchange.

At the same time, active electrolyte exchange requires regeneration and recirculation.

The gas analyzer according to the present invention is characterized by the following points. That is, the electrolyte in the tank is replaced with a volume exchange of 0.5 to 5 times per minute.The electrolyte is supplied to the circulation system at the inlet of the tank in order to regenerate the electrolyte in the tank, and the carbon of the electrolyte flowing out from the tank is activated carbon connected to the outlet of the waste reservoir and having an air inlet; Patrone is provided.

The ratio of gas flow overflow to electrolyte flow through is approximately 10-40 in this device.

The activated carbon cartridge, which in this case acts as a SO,-filter and has a significantly larger cross-section compared to the measuring tank, is used in such a way that a relatively large surface area is obtained on which the charcoal, electrolyte and oxygen can come into contact with each other. It is configured.

This configuration includes, in particular, a channel with a lower outlet, an open top end, a vertically arranged coarse activated carbon particle size of at least about 11 m, approximately 50 to 100 ml of coarse activated carbon! This is made possible by a cartridge containing a liquid and into which an electrolyte is added dropwise at the upper end.

In particular, the measuring electrode consists of charcoal, in particular formed with a graphite rod, while the counter electrode consists of copper. Advantageously, both electrodes are separated from each other by a membrane that essentially delimits the electrolyte flow.

For reasons of manufacturing technology, the electrode mechanism is installed in the vertical hole of the block, and the gas introduction tube is installed in this block by means of a diagonal hole with a branch tube opening at the lower end of the vertical hole. in which the two holes are connected to each other in the upper region via a connecting conduit (particularly obliquely inclined in the direction of the vertical holes), the extension of the connecting conduit extending from the bath. It is also possible to provide both holes at an angle, which function as gas outlet and electrolytic outlet. This coupling conduit is opened by an electrolyte inlet, which in particular is provided with an outflow capillary (at the bottom) and a leveling container provided above the coupling conduit.

In the electrolyte return circuit there is in particular a relatively large storage tank (with a volume of approximately 5 t) for the regenerated electrolyte, the liquid level of which is level-controlled. Regulated by water supply. In this way, losses due to evaporation are compensated and the electrolyte concentration is kept virtually constant. The liquid level in this reservoir is below the reservoir, so that the electrolyte flowing out of the reservoir passes through a 5O2-filter, in particular a subsequent mechanical filter (e.g. a paper filter or a textile filter or a glass filter). Advantageously, it can then be drained into this reservoir. A pump is connected to this vessel, which pump 802'ff: removes the free electrolyte from the reservoir (formed in particular by a leveling vessel with an outflow capillary to balance fluctuations in pump efficiency). into the element for electrolyte supply control.

Advantageously, twin vessels (each with a branch pipe for introducing gas for circulation) are provided, as described in European Patent Application No. 0 059 841. In this case, both vessels are preferably arranged as holes inside a single block. In this case, the second tank acts as a reference tank into which air is simply introduced, and the difference in flow between the two tanks is detected as a measured value. In this way, the incubation that would normally be necessary when measuring the 502-content of a chimney with different ambient temperatures is avoided.

The gas, in particular the flue gas, to be supplied to the electrolytic circulation system in suitable proportions is sampled, for example, from a chimney by means of a sonde and a gas feed pump and introduced into a measuring tank, in which case automatic control of the gas supply is carried out. Therefore, the above European patent application a.
A constant pressure mechanism as described in Ann is provided. However, the particularly hot gas is charged via a pressure regulator formed by a flow chamber with a partition wall essentially in the form of a spring-loaded membrane. The spring acts on one arm of a two-armed lever, the other arm of which is designed as a throttle flag for the gas supply. Advantageously, the spring pretension is adjustable by means of a screw. The removal of membranes for monitoring flue gases is particularly effective in view of high temperatures (in the range 100-200°C) from polytetrafluoroethylene with silicone rubber or textile reinforcement. The present invention will now be described in detail.

FIG. 1 shows a double tank mechanism 1 equipped with a measuring tank 2 and a reference tank 3.
is shown, and the electrolyte exiting this double tank mechanism passes through a common conduit 4 and reaches SO, - filter 5, from where it is further mechanically missed at position B, and then roughly The electrolytic solution from which impurities have been removed flows into a storage tank 7 equipped with a leveling pot.

The constant maintenance of the liquid level takes place via the water supply 8, which compensates for evaporation losses and keeps the concentration of the electrolyte virtually constant.

The pump 9 supplies the electrolyte through a conduit 10 to a leveling container 11.
From this leveling vessel the electrolyte flows via two capillary tubes 11' into vessels 2 and 3 (or a connecting conduit leading to a branch tube serving for gas introduction).

FIG. 2 is a sectional view of the S02 filter. The electrolyte applied from above at location 12 wets the activated carbon filling 13 and at the same time comes into contact with the incoming air at location 14 . The electrolyte from which 802 has been removed flows out from the lower end at position 15.

FIG. 3 shows a measuring tank 2 which is simple in terms of production technology and use. This measuring tank 2 is operated by a flow regulator 16 in a dedicated measuring gas supply pipe, and is provided in a common measuring tank block 1'. Inside the electrolytic cell 17 is a measuring electrode 1 taken from a carbon rod that oxidizes S02 containing an electrolyte.
8 is provided. A copper 'fj 19, which is separated from the carbon rod 18 by a filter 20, serves as the counterelectrode. A branch vessel 21 is connected to the electrolytic cell 17, at the lower end of which the measuring waste is introduced via a pipe 22. In this way, a small continuous electrode circulation occurs (due to the mammoth pump principle) in the manner illustrated by the arrows.

Fresh electrolyte enters at position 23 and gas and excess electrolyte reach position 24 from the paddle.

A coupling conduit leads from the electrode to a measuring and recording device for the boularographic flow (not shown). FIG. 4 shows a measuring block with a double tank of the tank type according to FIG. In the electrolyte guided by the circulation when S02 is removed outside the cell (from position 24 to position 23), the Cu-concentration change force that occurs during a long operation is corrected. Since the change is small when monitoring gases containing only 802 ml and has a weak influence on the measured value, in a good implementation of the device it can easily be used as a twin tank for both measurement and measurement. The reference tank can be replaced periodically, in which case the copper deposited in the reference tank in the measuring tank is contained in the gas (and is dissolved again by oxidation by oxygen). A pressure regulator 16 is shown in one of the compartment walls of the flow chamber, which is made of a corrosion-resistant elastic material capable of withstanding high temperatures, such as silicone rubber or Teflon with a textile core. It is divided by a membrane 26. A spring 27 acts on the membrane, the pretension of which is adjusted by a screw 28. One arm 29 of the two-armed lever is connected to this membrane, and the other arm 3
0 is provided with a valve element 31 in the vicinity of the inlet of the gas supply conduit 620. This valve element 61 is formed, in particular in front of the outlet 66, by a silicone rubber plate. At position 34 the gas leaves the pressure regulator. This pressure regulator is provided with holes 65 in the compartment wall above the membrane, which prevent gas backpressure from building up.

FIG. 6 shows the scum analyzer according to the invention installed in a chimney or waste gas conduit 36. The measuring gas is removed from this waste gas line via a gas sampling probe 67 via a line 38 which is equipped with a coarse and fine particle filter 39 and by means of a transfer pump 40 . At position "41", a measuring gas and a gauge gas or pure gas are applied via multiple paths.

The gas passes through a pressure regulator 16 (as shown in diagram 5) (
1), in which the electrolyte is guided through the circulation system in the manner shown. In this case, the electrolyte coming from both tanks passes through the 8.02-' filter 5 into the electrolytic storage vessel 7, from which fresh electrolyte is returned to the double tank by the electrolyte pump 9. At position 42, the left-hand electrical sensor is shown.

Reference numeral 43 designates the slider, reference numeral 44 designates the casing containing the important parts of the analyzer (parts 16° 37-41 and 45 shown on the left side of the casing are arranged so as not to fall below the dew point of the gas to be measured). ).

Example: A mixture consisting of nitrogen with a given SO,- concentration is 38
Analyzer heated to 20°C (vessel with gas conduit branches and connections of approx. 10-) guided at a rate of 0-gas 7 min.
Electrolyte solution (0,5m H2SO4+ 0-2
If one or two solution exchanges per minute of mCuSO4) are carried out, a calibration curve as shown in FIG. 7 is obtained. The signal magnitude is stable over time when the 5O2 concentration is constant. The time required to change the signal height by a factor of 90 (τ90) was about 110 seconds. 90 is obvious (200 seconds and more) with a capacity exchange of less than 0.5
becomes longer. The signal stability was then low and the steepness of the calibration curve was reduced.

[Brief explanation of the drawing]

FIG. 1 shows the electrolyte pump for the SO□-analyzer with double tank, FIG. 2 shows the S02-filter (in ~r view), and FIG. 3 shows the flow control in the gas supply conduit. Figure 4 shows the double tank arrangement according to Figure 3 (in full plan view); Figure 5 shows the gas supply conduit; Figure 6 shows the installation of the analyzer in the chimney using the gas line, and Figure 7 shows the calibration curve. Symbols in the figure are 11... Supply control element 12... Electrolyte supply section 14... Air supply port 15... Electrolyte discharge section 17.21... Tank agent Mitsuyoshi Ezaki agent Mitsufumi Ezaki

Claims (1)

[Claims] 1. Two measuring vessels each having a measuring electrode indicating a negative flow of the gas to be measured in an equal electrolytic solution and a non-polar counterelectrode, the electrolyte being separated from the bath. an electrolytic solution containing a gas is discharged through an intermediate chamber between the measuring electrolyte and the counterelectrode as a circulating flow through the measuring gas conduit, guided in the circulating flow and continuously regenerated;
Electrochemical sludge analyzer for the 5O2 content in gases, in particular flue gases, in such a way that the s02 dissolved in the electrolyte is treated with air in the presence of activated carbon outside the tank and disposed of. , the tank (
a feeding control element (11) in the circulation system at the inlet of the tank for regenerating the electrolyte in 17) with 21 and the electrolyte charcoal exiting the tank is at least partially wetted only by the liquid; 502 in the scale and arrangement of the electrolyte supply part (12) and the electrolyte outlet part (15) - an activated carbon cartridge connected to the outlet of the tank for disposal and having an air inlet (14); A gas analyzer characterized in that: 2 The activated carbon cartridge is open at the top and is at least 11
111110 particle size activated carbon filling (13) 50-100
- and is formed by a vertical cartridge having a lower outlet (15), an upper drip feed (12) and an air flow opening (14) at its upper end. The gas analyzer according to item 1. S,? 111) Constant electrode and counter electrode (18, 19
) are provided in a common vertical hole of the measuring tank block, at the lower end of this hole there is an inclined hole for the gas introduction conduit, and this gas introduction conduit has a connection at the upper end leading to the vertical hole. 4. A gas analyzer according to claim 1 or claim 2, comprising a conduit and having an electrode supply conduit (11 open) in the coupling conduit. 4. The electrolyte supply control element is located at the bottom. Outflow capillary (11'
) and a leveling container (11) to which liquid is supplied by a pump (9), a branching tank (21) that is useful for introducing waste
A gas analyzer according to any one of the claims 1 to 6, wherein the gas analyzer is formed above a coupling conduit between the gas analyzer and the vessel (17) containing the electrodes. . 5. The electrolyte circulation system is provided with a storage tank (7) whose liquid level is controlled via a water supply conduit whose liquid level is controlled and from which the regenerated electrolyte is taken out by a pump (9). ,%
The gas analyzer according to any one of the first to fourth terms of the range of measurement requirements. 6. A double tank is formed that serves as a reference tank to detect the difference in the flow of both tanks and supplies gas that does not contain 802 to the second tank; in this case, the first tank and the second tank are 6. Gas analyzer according to claim 1, wherein the two vessels (2, 6) are arranged in parallel in the same electrolyte-regeneration circulation system. Z with a partition wall in the form of a spring-loaded membrane (26) acting on one arm (29) of a two-armed lever, the other arm (60) of which is formed as a throttle flag of the gas supply (32); A pressure regulator (25) having a flow chamber (25)
16) in the measuring gas supply conduit (36).