TWI497066B - Sulphite sensor and method for measuring sulphite concentration in a substance - Google Patents

Description

Sulfite sensor and method for measuring sulfite concentration in a substance

The present invention relates to a method for measuring the concentration of sulfite in a substance in a gas purification process.

The invention further relates to a sulfite sensor adapted to measure the concentration of sulfite in a substance in a gas cleaning apparatus.

In many industrial processes, process gases containing acid gases are produced. One such industrial process may burn a fuel (such as coal, petroleum, peat, waste, etc.) in a combustion plant, such as a power plant, thereby producing one of the contaminants (which contain acid gases) Heat treatment gas or "flue gas". The process gas needs to be treated to remove at least a portion of the acid gases. This treatment can be provided in a wet scrubber such as disclosed in EP 0 162 536. The disclosed wet scrubber includes an absorbent that is in contact with the process gas to absorb at least a portion of the acid gases. For example, the absorbing liquid can be atomized through the nozzle to react with the processing gas.

The processing program can be controlled based on one of the information related to the status of the processing program. This information may include the measured properties of the absorbing liquid. One common way to control a wet scrubber is to measure the pH level of the absorbent and thereby provide information that can be used to control the supply of fresh absorbent, such as limestone, to the absorbent.

However, measuring the pH of an absorbent is not reliable. pH measurement is a difficult process that does not provide reliable information about the nature of the absorbent. This reduces the control accuracy of the processing program and the efficiency of the wet scrubber.

Therefore, there is a need to more reliably measure the nature of one of the liquid purification devices to control the process of purifying a process gas.

It is an object of the present invention to provide an improved method relative to the prior art by which reliable information relating to the nature of a substance in a gas purification process is provided.

This object is achieved by a method for measuring a concentration of sulfite in a substance in a gas purification process, the method comprising the steps of: transmitting a plurality of signals by passing a first electrode and a second electrode through the substance a voltage pulse, the first and second electrodes are in contact with the substance; receiving a current response generated by the plurality of voltage pulses; and analyzing the current response using multivariate data analysis to calculate a sulfite concentration in the substance .

One of the advantages of this method is that the sulfite content of the material can be measured in a more reliable manner. Further, a low sulfite concentration can be measured with high precision by the present method. Thereby, the gas purifying process can be controlled with high precision. If the substance is one of the wet scrubbers (for example, a wet scrubber using limestone as one of the absorbents), the method according to the invention provides a reliable measure of one of the sulfite concentrations in the absorbent, An input is thus provided to control the processing of one of the processing gases in the wet scrubber. The method can use voltammetry. In the method, a voltage pulse can be transmitted through a first electrode and a second electrode in the substance. The second electrode can be a large piece of metal. The second electrode may have an area that is at least 20 times larger than the area of the first electrode. Processing the current response generated by the voltage pulses by using multivariate data analysis, using from a known sulfite concentration The mathematical model of the sample is used to establish a predictive model that can be used to determine the concentration of sulfite in an unknown substance.

According to an embodiment, the step of transmitting the plurality of voltage pulses may include transmitting a plurality of voltage pulses in the series to gradually increase and/or decrease the voltage level.

By gradually increasing and/or decreasing the voltage level, a series of voltages transmitted through the first electrode may be in a stepped shape. A voltage pulse can be generated to generate a current response when the voltage level is increased or decreased to a new level. During one measurement of the sulfite concentration, the voltage level can be scanned stepwise (from a first voltage level to a final voltage level). The first voltage level can be a negative voltage and the final voltage level can be a positive voltage to cause an anode scan. Alternatively, the first voltage level can be a positive number and the final voltage level can be a negative number to result in a cathode scan.

According to an embodiment, the step of analyzing the current response comprises analyzing the peak of the current response using multivariate data analysis.

An advantage of this embodiment is that multivariate data analysis is an efficient way to obtain one of the sulphite concentrations from the information available in the current response.

According to an embodiment, the step of analyzing the current response may comprise analyzing the one peak of each current response and at least another value using multivariate data analysis.

When measuring a sulfite in a substance, a series of voltages are transmitted through the first electrode to cause a series of current responses. The peak shape of each current response provides information about the sulfite in the material. The current response can include one of the peak levels of current and an attenuation. Can extract electricity from many samples The stream responds to the sample to provide a number of values. The peak of each current response and at least another value are analyzed to be sufficient to assess the sulfite concentration in the material using multivariate data analysis. Thereby, the amount of data processed in the analysis is reduced compared to analyzing a complete peak or a plurality of data values (ie, all sample values). Only two values can be used to provide a reliable measure of one of the sulfite concentrations. The sulfite may have a redox potential at which one of the current responses may be greater than the current response at other potentials. The current response provides a peak-shaped increase in current level when a series of voltage pulses approaches a voltage level corresponding to the redox potential of the sulfite. This increased current level can be identified when analyzing the peak of each current response. In an embodiment, the at least one value other than the peak may be four values. This value can be obtained when the current is responsive to attenuation to provide further information regarding the sulfite content of the material. As an example, each current response sample can be extracted in 50 samples. If multivariate data analysis can be used to analyze five values (which include the peak), then three of the values (which include the peak) can be taken from the first 1/3 of the sample. In addition, a value can be taken from the second 1/3 of the sample, and a value is obtained from the last 1/3 of the sample. In an embodiment, the peak may be from a first or second sample of each current response.

According to an embodiment, the method may further comprise cleaning a surface of the first electrode to remove a coating caused by contact between the first electrode and the substance.

The first electrode can be made of platinum. When a substance containing a subsulfide compound is measured, the first electrode becomes relatively unusable due to the adhesion of the sulfide to the platinum surface of the electrode. This can form a coating on the surface of the electrode and negatively affect the results of the measurement. The coating can be removed by cleaning the surface of the electrode Ensure the reliability of the measurement. The electrode can be cleaned continuously or semi-continuously. Cleaning can be performed by a cleaning unit such as a brush, a grinder, a scraper or the like.

According to an embodiment, the value of each voltage pulse transmitted through the substance may be 0.02 volts to 0.2 volts higher or lower than the previous adjacent voltage pulse.

Each voltage pulse can have a voltage level increment or decrement. For each voltage pulse, the voltage level can have an increment or decrement between 0.02 volts and 0.2 volts. Preferably, the voltage level can have an increment or decrement of about 0.05 volts. A complete measurement of one of the sulfites in the material can, for example, begin at a voltage of -0.9 volts, which is increased to 0.8 volts in a stepwise manner. A current response can be received based on each voltage pulse or step. A plurality of current responses can be received after a voltage sweep. Each current response is peak shaped and multivariate data analysis can be used to analyze the first and last current values. By providing a step-by-step voltage sweep, the plurality of current responses provide reliable information about the concentration of sulfite in the material.

According to an embodiment, the step of cleaning a surface of the first electrode may include rotating a cleaning unit into contact with the first electrode.

A cleaning unit can be rotated into contact with the first electrode to provide continuous cleaning of one of the electrodes. Thereby, the coating formed on the surface of the electrode can be continuously removed. The cleaning electrode can be brushed, ground, scratched or otherwise treated in an electrode. The first electrode can be annular to provide extended contact with one of the substances. An annular first electrode can further provide continuous contact with the rotary cleaning unit.

According to an embodiment, the cleaning unit can be rotated to a surface with one of the first electrodes at a rate of 2 revolutions per minute to 40 revolutions per minute (2 rmp to 40 rmp) contact.

The coating on the surface of the first electrode can be continuously removed by rotating the cleaning unit into contact with one of the first electrodes at a rate of about 2 revolutions per minute to about 40 revolutions per minute, and can be reliably implemented. Perform measurements. The cleaning unit does not interfere with the transmission of voltage pulses. Preferably, the cleaning unit can be rotated at a rate of about 15 revolutions per minute. The rate of rotation of the cleaning unit can be varied over time to provide a rate interval to the cleaning unit.

According to an embodiment, the substance may be one of the absorbents used in a wet scrubber purification procedure.

In a gas purification process (such as in a wet scrubber adapted to purify the process gas), an absorption liquid that reacts with an acid gas in the process gas, such as one based on limestone, may be provided. These acid gases may include sulfur dioxide. This reaction can result in the absorption liquid containing sulfite. The sulfite concentration in the sorbent provides information on the status of the gas purge process that can be used to control the wet scrubber. The wet scrubber can be controlled in a reliable manner by providing a reliable sulfite measurement method to the absorbent.

According to another aspect, a sulfite sensor for measuring a sulfite concentration in a substance in a gas purification device, wherein the sulfite sensor comprises: a first electrode and a second An electrode, which is adapted to be in contact with the substance; a control unit adapted to transmit a voltage pulse by the first electrode and the second electrode transmitting the substance; and an analysis unit adapted to receive and A current response generated by the voltage pulses is analyzed, wherein the analysis unit is adapted to perform multivariate data analysis.

One of the advantages of this sulfite sensor is that it can perform a reliable measurement of one of the sulfite concentrations in a substance. The measured values can then be used to control the gas purification process. This sulfite concentration can be reliably measured even when the sulfite concentration is very low. The control unit can transmit a voltage pulse to the substance through the first electrode. A current response generated by the voltage pulses can be received through a second electrode. The second electrode can be a metal piece. By using multivariate data analysis in the analysis unit, a mathematical model from a sample having a known sulfite concentration can be used to establish a predictive model that can be used to determine the sulfite concentration in an unknown substance.

According to an embodiment, the control unit can be adapted to transmit a series of voltage pulses such that one of the voltage pulses can be increased and/or decreased in a stepwise manner.

A series of voltage pulses transmitted through the first electrode can be in a stepped shape by increasing and/or decreasing the voltage level step. A voltage pulse can generate a current response when the control unit increases or decreases the voltage level to a new level. The sulfite sensor can be adapted to step through the voltage level (from a first voltage level to a final voltage level) to measure the sulfite content. The first voltage level can be a negative voltage and the last voltage level can be a positive voltage to cause an anode scan. Alternatively, the first voltage level can be a positive number and the last voltage level can be a negative number to cause a cathode scan.

According to an embodiment, the analysis unit can be adapted to perform a multivariate data analysis based on the peak of the current response.

One of the peaks of the current response provides information about the sulfite in the substance. The current response can include a peak level and the current tends to zero Less. A reliable measurement of one of the sulfite concentrations can be achieved if the analysis unit analyzes the peak of the current response. The sulfite may have a redox potential at which one of the current responses may be greater than the current response at other potentials. If the voltage pulse sent by the control unit corresponds to the redox potential of the sulfite, the current response peak provides an increased current level. However, when measuring a rough complex medium (as a liquid from a gas purification process), a clear peaking current level at the redox potential cannot be obtained. This is due to the fact that the measurement of more or less redox active substances in the medium leads to a very complicated one-current response. This makes this current response from a measurement very difficult to interpret. Therefore, multivariate data analysis is used to interpret data from a current spectrum. Next, a current spectral training set with a known sulfite concentration is used to generate a mathematical prediction function for samples having unknown sulfite concentrations. An example of a current spectrum is shown in Figure 4c.

According to an embodiment, the sulfite sensor may further comprise a cleaning unit adapted to clean one of the first electrodes.

The first electrode can be made of platinum. When a sulfite sensor is used to measure a substance containing a subsulfide compound, the first electrode becomes relatively unusable due to the sulfide bonding to one of the platinum surfaces of the electrode. This forms a coating on the surface of the first electrode and negatively affects the results of the measurement. The coating on the surface of the electrode can be removed by providing a sulfite sensor having a cleaning unit to ensure the reliability of the sensor. The cleaning unit can be adapted to clean the first electrode in a continuous or semi-continuous manner during the measurement of the sulfite. The cleaning unit can be a brush, a grinder, a scraper or the like.

The invention is described in more detail with reference to the drawings.

The invention will be described more fully hereinafter with reference to the accompanying drawings in which <RTIgt; However, the present invention may be embodied in many different forms and should not be construed as being limited to the embodiments described herein; rather, the embodiments are provided so that the present invention is thorough and will be fully conveyed to the skilled artisan. The scope of the invention. In the drawings, the same component symbols mean the same components.

A perspective view of a sulfite sensor 1 in accordance with the present invention is illustrated in FIG. 1, and a schematic side cross-sectional view of the sulfite sensor 1 is illustrated in FIG. The sulfite sensor 1 comprises: a base section 4; and a casing 2 forming a side wall for a space 3 for sulfite detection. A sensor head 10 is located in the space 3. The sensor head 10 is formed to extend into one of the tubes in the space 3. One of the first electrodes 11 in the form of a platinum ring is disposed at one of the axial end portions 13 of the sensor head 10. One surface 12 of the first electrode 11 is flush with the axial end portion 13 of the sensor head 10.

A shaft 31 extends through the interior 10a of the tubular sensor head 10. An electric motor (not shown) rotates the shaft 31. The shaft 31 is coupled to a grinding unit 30. The grinding unit 30 has a surface 32 that is adapted to abut the surface 12 of the first electrode 11 (as best shown in Figure 2). The shaft 31 rotates the grinding unit 30 such that the surface 32 of the grinding unit 30 grinds/cleans the surface 12 of the first electrode 11. The grinding unit 30 is rotated to contact the surface 12 of the first electrode 11 at a rate of 2 revolutions per minute to 40 revolutions per minute, preferably at a rate of 15 revolutions per minute. The grinding unit 30 is preferably made of one based on, for example, tantalum carbide or tantalum nitride Made of porcelain material.

The sulfite sensor 1 further includes a second electrode 20. The second electrode 20 is preferably made of a metal such as steel or the like. The second electrode 20 is located at a distance from the first electrode 11. In the illustrated embodiment, the second electrode 20 is constructed from a metal casing 2.

A control unit 40 is disposed in the sulfite sensor 1 or connected to the sulfite sensor 1 and adapted to transmit a voltage pulse through a substance occupying a space between the first electrode 11 and the second electrode 20 . When the sulfite sensor 1 is immersed in a substance, the voltage pulses enter the substance via the first electrode 11. The second electrode 20 is adapted to receive a current response generated by the voltage pulses and to pass back the current responses to the control unit 40. Control unit 40 receives and analyzes (using an analysis unit 50) the current responses and uses a multivariate data analysis to calculate the sulfite concentration in the material. By using multivariate data analysis in analysis unit 50, a mathematical model from a sample having a known sulfite concentration is used to establish a predictive model that can be used to determine the sulfite concentration in an unknown substance.

Information from voltammetric measurements is often difficult to interpret. Each measurement consists of a number of variables. Multivariate data analysis methods (such as principal component analysis (PCA) and latent structure projection (PLS), for example, from the following: Wold, S., Esbensen, K. and Geladi, P. "Principal component analysis: A Tutorial.", Chemometrics and Intelligent Laboratory Systems 2, 37-52, 1987; and "PLS-regression: a basic tool of chemometrics" by S. Wold, M. Sjöström and L. Eriksson, Chemometrics and Intelligent Laboratory Systems, 58 ( 2001) 109-130) has been shown to be useful. PCA is a mathematical tool that describes the variance of experimental data. A vector is calculated which describes the direction of the largest variance of the experimental data, ie, the direction of the largest difference between the observed data. This vector is called the first principal component. The second principal component is orthogonal to the first principal component and thus independent of the first principal component. The other principal components can be calculated in a similar manner until most of the observations have been interpreted. Next, a new matrix defined by the principal components is formed, and the data set is substantially reduced according to the importance of the different principal components, but in many cases only reduced to two dimensions. The load vector describes the direction of the principal component associated with the original variable, and the score vector describes the direction of the principal component associated with the observed data. Therefore, a score map can be made to show the relationship between the original samples and the extent to which they affect the system. Therefore, a score map shows the relationship between experimental data, and the grouping of experimental data can be used for classification.

PLS is used to generate a model of the calibration set from the data. PLS is a linear method in which PCA is performed on both X data (voltammogram) and Y data (density). Next, a linear regression is performed on each PC between the data set and the Y data to give a regression model. This model can be used to predict values from voltammograms.

Available in ITJolliffe's "Principle Component Analysis" (Springer-Verlag, New York Company (1986) ISBN 0-387-96269-7) or KRBeebe, RJPell and MB Seasholtz "Chemometrics-A practical guide" (John Wiley) More information on multivariate data analysis can be found in & Sons (1998) ISBN 0-471-12451-6).

In an embodiment, the sulfite sensor 1 further comprises for measuring One of the temperatures of the temperature sensor 60.

Figure 3 is a flow diagram of a method 80 for measuring the concentration of sulfite in a substance. This material can be supplied in a gas purification process. In a step 82, a plurality of voltage pulses are transmitted through the first electrode 11. The first electrode 11 is in contact with the substance. The first electrode 11 and the second electrode 20 transmit a voltage pulse from the control unit 40 as a stepwise increasing or decreasing voltage level (as shown in Figure 4a). A step pattern of a voltage level transmitted through the first electrode 11 is formed. Each step involves increasing or decreasing the voltage level by about 0.05 volts. In one example of the method, the voltage level transmitted as a voltage pulse (as a voltage pulse) is increased from -1.0 volts to 1.0 volts in a stepwise manner (step is 0.05 volts). In another example, depicted in Figure 4a, the voltage level first drops from 0.8 volts to -0.1 volts (steps are 0.05 volts), then rises from -0.1 volts to 0.8 volts (steps are 0.05 volts).

In a step 84, a current response is received which is generated in response to a voltage pulse transmitted by the first electrode 11 to the second electrode 20. The second electrode 20 receives the current responses. The second electrode 20 is also in contact with the substance. Each step of increasing or decreasing the voltage level produces a new current response in the second electrode 20.

In a final step 86, a multivariate data analysis is used to analyze the current response. Thereby, the sulfite concentration in the substance can be measured based on the current response. According to an embodiment, all of the plurality of current responses are used to measure the sulfite concentration in the substance. In an embodiment, the current response is analyzed after each transmit voltage pulse. Alternatively, a series of voltage pulses are sent to generate a series of current responses prior to performing a multivariate data analysis on a series of current responses.

Figure 4b further shows an exemplary simulation of one of the voltage pulses in a stepped pattern. The voltage level changes from about -0.75 volts to about 0.8 volts over time. The value on the x-axis represents the number of voltage pulses. Figure 4c shows the corresponding current response as an output voltage from one of the electronic circuits. Information from these current responses is used to assess the sulfite content of the material (using multivariate data analysis). As shown in Figure 4b, each voltage pulse corresponds to the five measured voltage values in Figure 4c. Thus, in the example shown in Figures 4b and 4c, the response of each voltage pulse is measured five times during each voltage pulse. The value on the x-axis of Figure 4c represents the number of measurements.

As an exemplary application of the sulfite sensor 1 according to the present invention, FIG. 5a illustrates a wet scrubber 101. The wet scrubber 101 is operable to remove at least a portion of a sulfur dioxide content of a process gas produced in a form of flue gas F produced in a boiler (not shown) operable to combust a fuel, such as coal , oil, peat, natural gas or waste.

The wet scrubber 101 comprises: an absorption vessel in the form of a vertically open tower 102; an inlet 104 for the flue gas F to be purified; and an outlet 106 for at least a portion of the sulfur dioxide content The flue gas FC is removed.

An absorbing liquid oxidation vessel in the form of an absorbing liquid reservoir 108 is disposed at the bottom 109 of the vertical open tower 102. The absorbing liquid reservoir 108 achieves dual use: acting as a recirculating sump for one of the absorbing liquids; and acting as one of the containers in which oxidation can occur. For the latter reason, the absorbing liquid reservoir 108 has an oxidizing configuration 110. The oxidation configuration 110 includes an oxygen supply device 112 in the form of a blower 112a, and an oxygen distributor 114 including a distribution tube 118 A plurality of nozzles 116; and a supply tube 120 fluidly coupled to the blower 112 and the distribution tube 118 to supply compressed oxygen-containing gas, such as air, to the dispensing tube 118 and the nozzle 116. The nozzle 116 is configured to distribute air into one of the limestone absorbing liquid contained in the absorbing liquid storage tank 108 and cause oxidation of the sulfite contained in the limestone absorbing liquid, as described in more detail below. It will be appreciated that as an alternative to a blower 112a, the oxygen supply device 112 can be a compressor or some other device suitable for compressing an oxygen-containing gas into the absorbent of the absorbent reservoir 108. Further, the oxygen-containing gas blown by the blower 112a may be, for example, air, a certain purity of oxygen (such as one gas including 90% by volume to 99% by volume of oxygen) or a mixture of oxygen and air.

It will show, for example, fresh limestone (CaCO ₃₎ in the form of an absorbent material from the absorbent supply system 122 is supplied to the absorption liquid storage tank 108. The absorbent supply system 122 includes a limestone storage bin 124, a fluid connection supply conduit 126, and a mixing reservoir 128 including a stirrer 130. In the mixing tank 128, the water supplied via the fluid connection supply pipe 126 is mixed with the limestone powder supplied from the limestone storage tank 124 to form a limestone slurry. The limestone slurry is supplied from the mixing tank 128 to the absorbing liquid storage tank 108 via a fluidly connected limestone supply pipe 132. It should be understood that as an alternative, the sorbent sump 108 can be positioned external to the tower 102; and as an alternative, the supplied limestone can enter the system at other locations in the form of dry powder, slurry, or both. Limestone (CaCO ₃ ) can be at least partially dissolved in water: CaCO ₃ (solid) + H ₂ O <=> Ca ²⁺ (solution) + CO ₃ ^2- (solution) [Reaction formula 1]

The wet scrubber 101 further includes a scrubber circulation pump 134 that circulates the limestone absorbing liquid from the absorbing liquid sump 108 via the absorbing liquid circulating pipe 136. The two spray level systems 138, 140 positioned within the open tower 102 are looped.

Each spray level system 138, 140 includes a piping system 142 and a plurality of fluid connection spray nozzles 144 that fluidly distribute the limestone absorbent circulating by the scrubber circulation pump 134 to achieve limestone absorbent and flue gas F ( It is in effective contact between the wet scrubber 101 and substantially vertical upward flow inside the open tower 102. All or a portion of the fluid connection spray nozzle 144 can be, for example, the 4CF-303120 model available from Spraying Systems, Inc. (Wheaton, Illionis, USA). In the open tower 102 of the wet scrubber 101, the following reaction occurs after the limestone absorbing liquid finely distributed by the fluid connection spray nozzle 144 absorbs the sulfur dioxide (SO ₂ ) contained in the flue gas F: SO ₂ (gaseous state) +CO3 ^2- (solution) + Ca ²⁺ (solution) <=> CaCO ₃ (solution) + CC ₂ (gaseous state) [Reaction formula 2]

An mist eliminator 146 is located downstream of the spray level systems 138,140. The mist eliminator 146 removes at least a portion of the absorbed droplets from the purified flue gas FC.

In the wet scrubber 101, sulfur dioxide (SO ₂ ) in the flue gas F reacts with limestone (CaCO ₃ ) to form calcium sulfite (CaSO ₃ ), which is subsequently oxidized to form calcium sulfate (CaSO ₄ ). . Oxidation of the calcium sulfite is performed by using an oxidizing arrangement 110 to cause an oxygen-containing gas, such as air, to escape through the limestone absorbing liquid. The following reaction can occur in the absorbing liquid storage tank 108: CaSO ₃ (solution) + 1/2 O ₂ (gaseous state) <=> CaSO ₄ (solid state) + 2 H ₂ O [Reaction formula 3]

Thus, calcium sulphate (CaSO ₄ ), which is sometimes described as containing two water molecules, ie, CaSO ₄ × 2H ₂ O, is formed into the final product. It has been described above that the absorbed SO ₂ produces calcium sulfite (CaSO ₃ ). It will be appreciated that at least a portion of the absorbed SO ₂ will produce calcium hydrogen sulfite (Ca(HSO ₃ ) ₂ ) (solution) depending on the conditions, and will oxidize calcium hydrogen sulfite according to principles similar to those of [Reaction 3] above. .

Therefore, the limestone absorbing liquid includes a small amount of calcium sulfite and calcium sulfate as a main component in addition to limestone. The calcium sulphate formed by this procedure is removed from the wet scrubber 101 via a disposal tube 148 and transferred to a calcium sulphate dewatering unit (shown schematically as a belt filter 150). Dehydrated calcium sulphate has commercial value, for example for the production of wallboard.

Wet scrubber 101 except removal of sulfur dioxide (SO ₂₎ except that the other will also be at least partially remove contaminants from the flue gas. Examples of such other contaminants include sulfur trioxide (SO ₃ ), hydrochloric acid (HCI), hydrofluoric acid (HF), and other acidic contaminants. In addition, the wet scrubber 101 can also at least partially remove other types of contaminants from the flue gas, such as, for example, dust particles and mercury.

A control unit 152 controls the operating parameters of the wet scrubber 101. The wet scrubber 101 has an absorption liquid sampling system 154 that supplies measurement data to one of the control units 152. The sampling system 154 includes a direct sampling device 156 and an absorbent sump sampling device 158.

The direct sampling device 156 includes a collector 160 for capturing droplets of absorbing liquid just above the surface 162 of one of the absorbing fluids of the sump 108. Captured by the absorption liquid droplets of the droplet collector 160 following: and the like which have been fluidly connected atomizing spray nozzle 144 and the absorbing sulfur dioxide (SO ₂₎ through the open tower 102, but has not been exposed to oxidative configuration 110 Oxidation. The droplets of the absorbing liquid captured by the collector 160 have not been in contact with the absorbent material supplied via the absorbent supply system 122. The absorbing liquid captured by the collector 160 is transferred to a first pH analyzer 166 and a first sulfite analyzer 168 via a fluid connection tube 164. The first sulfite analyzer 168 includes a sulfite sensor 1.

The absorbent sump sampling device 158 includes a tube 170 fluidly coupled to the absorbing fluid reservoir 108. The absorbing liquid collected from the sump 108 via the tube 170 is transferred via a tube 170 to a second pH analyzer 172 and a second sulfite analyzer 174. The oxidizing arrangement 110 causes the absorbing liquid contained in the sump 108 to be agitated, and therefore, the sump 108 can be regarded as one of the continuous agitated sump reactors in which the oxidation reaction takes place. Another agitator can be disposed in the sump 108 as appropriate.

Fluid connection tube 164 and tube 170 are fluidly coupled to a circulation tube 176. A circulation pump 178 is disposed in the circulation pipe 176 to pump the absorption liquid that has passed through the direct sampling device 156 and the absorption liquid storage tank sampling device 158 to the absorption liquid storage tank 108. Shut-off valves 180, 182, and 184 disposed in fluid connection tube 164, tube 170, and circulation tube 176, respectively, can collect an absorbent sample via sample tube 186 and associated shut-off valve 188 for manual analysis via direct sampling device 156 or absorbent The sulphate concentration and/or pH of the absorbing liquid collected by the sump sampling device 158.

The control unit 152 receives the measurement signals from the analyzers 166, 168, 172, and 174, and controls at least one of: a control valve 190 disposed in the limestone supply tube 132 and controlling the self-mixing sump 128 based on the measurement signals. The amount of limestone slurry supplied to the absorption liquid storage tank 108; the scrubber circulation pump 134; and the blower 112 of the oxidation configuration 110. In addition, control unit 152 may also receive measurement signals from a first SO ₂ analyzer 192 to measure SO ₂ concentration in flue gas F entering open tower 102 of wet scrubber 101, and from a second SO ₂ analysis 194 receives the measurement signal from the measurement of the wet scrubber 101 via the opening ₂ concentration of the purified flue gas is discharged FC column 102 of SO.

FIG. 5b illustrates a collector 160 in accordance with an alternate embodiment. The collector 160 is fully disposed within the open tower 102 and includes a funnel portion 196 disposed within the open tower 102, the funnel portion 196 being located above the surface 162 of the absorbent contained in the absorbent reservoir 108. Droplets LD produced by the fluid connection spray nozzle 144 depicted in Figure 5a and dripped down into the interior of the open tower 102 are collected in the funnel portion 196. The funnel portion 196 has its bottom 197 connected to an "S" shaped discharge tube 199. The drain 199 will act as a water trap to ensure that a certain amount of collected liquid is present in the funnel portion 196. One of the outlets 195 of the discharge tube 199 is open above the surface 162 to avoid any siphoning effect. A first sulfite analyzer 168 extends into the collection absorbing liquid of the open column 102 and the funnel portion 196. The first sulfite analyzer 168 can include the sulfite sensor 1 described above with reference to Figures 1-4. The funnel portion 196 and the discharge tube 199 ensure that the sulfite sensor 1 measures the concentration of sulfite in the newly collected absorbent.

Another illustrative application of sulfite sensor 1 is illustrated in Figure 6a, which shows a schematic side cross-sectional view of one of power plants 201. The power plant 201 includes a boiler 202 in which one of the fuel (such as coal, petroleum, peat, natural gas, or waste) is supplied via the feed pipe 204 in the presence of oxygen supplied via the oxygen supply pipe 206. If the boiler 202 is a so-called "oxygen fuel" boiler, oxygen may be supplied, for example, in the form of air and/or in the form of a mixture of oxygen and recycle gas. Combustion of the fuel produces a heat treatment gas in the form of a flue gas. The sulfur species contained in the fuel form sulfur dioxide (SO ₂ ) after combustion (which will form part of the flue gas).

The flue gas may flow from the boiler 202 through a fluid connection tube 208 to an optional dedusting device in the form of an electrostatic precipitator 210. Electrostatic precipitator 210 (an example of which is described in US 4,502,872) uses dust from flue gas to remove dust particles. As an alternative, another type of dust removal device can be used, such as a fabric filter (an example of which is described in US 4,336,035).

The flue gas from which most of the dust particles have been removed flows from the electrostatic precipitator 210 to a seawater scrubber 214 via a fluid connection pipe 212. Seawater scrubber 214 includes a wet scrubber tower 216. An inlet 218 is disposed at a lower portion 220 of one of the wet scrubber towers 216. Tube 212 is fluidly coupled to inlet 218 such that flue gas flowing from electrostatic precipitator 210, via tube 212, can enter interior 222 of wet scrubber column 216 via inlet 218.

After entering the interior 222, the flue gas flows vertically upward through the wet scrubber tower 216 as indicated by arrow F. The central portion 224 of the wet scrubber tower 216 is equipped with a plurality of spray configurations 226 that are vertically disposed on each other. In the example of Figure 5a, there are three such spray configurations 226, and one wet scrubber tower 216 typically has from 1 to 20 such spray configurations 226. Each spray configuration 226 includes a supply tube 228 and a plurality of nozzles 230 fluidly coupled to respective supply tubes 228. Water is supplied to the nozzle 230 by the atomizing nozzle 230 in the interior 222 of the wet scrubber tower 216 is in contact with the flue gas from the flue gas to absorb sulfur dioxide (SO ₂₎ via a respective supply tube 228.

A pump 232 is configured to draw seawater from the ocean 236 via the fluid connection suction tube 234 and transfer the seawater to the fluid connection supply tube 228 via a fluid connection pressure tube 238.

According to an alternative embodiment, the seawater supplied to the tube 228 by the pump 232 may be the aforementioned seawater, which is used in the steam turbine system associated with the boiler 202 before the seawater is used as the wash water in the seawater scrubber 214. Cooling water.

The seawater atomized by the nozzle 230 in the interior 222 of the wet scrubber tower 216 flows downwardly within the wet scrubber column 216 and flows vertically from the interior 222 of the wet scrubber column 216. Absorbs sulfur dioxide. As the seawater absorbs the sulphur dioxide, the seawater gradually becomes contaminated seawater while flowing downward in the interior 222 of the wet scrubber tower 216. The contaminated seawater is collected in a portion 220 below the wet scrubber tower 216 and transferred from the wet scrubber column 216 to the oxidation pond system 242 via the fluid connection sewer 240.

According to an alternate embodiment, the seawater scrubber 214 can include one or more layers of packing material 239 disposed in the interior 222 of the wet scrubber column 216. The gas-liquid contact can be enhanced by a filler material 239 made of plastic, steel, wood or another suitable material. In the case of the filler material 239, the nozzle 230 only distributes seawater to the filler material 239, rather than atomizing seawater. Examples of the filler material 239 comprises a commercially available from Sulzer Chemtech AG, Winterthur, CH and the Mellapak ^TM available from Raschig GmbH, Ludwigshafen, DE Pall ^TM of the ring.

Fresh seawater can be added to contaminated seawater as appropriate, before further treatment of contaminated seawater. To this end, a tube 249 can be fluidly coupled to the pressure tube 238 to transfer a stream of fresh seawater to the fluid connection sewer 240 that transfers the contaminated seawater to the oxidation pond system 242. Therefore, fresh seawater is mixed with one of the polluted seawater in the fluid connection sewage pipe 240. As an alternative For example, fresh seawater transferred via line 249 can be directly transferred to oxidation pond system 242 for mixing with contaminated seawater in oxidation pond system 242. Alternatively, residual water and/or condensate produced in boiler 202 or a steam turbine system associated therewith may be mixed with contaminated seawater.

Oxidation cell system 242 includes an air blower in the form of a compressor or a blower 244 that is configured to blow an oxygen-containing gas, such as air, into the contaminated seawater via fluid connection conduit system 246. The blower 244, together with the piping system 246, forms an oxygen supply system 247 for supplying oxygen to one of the contaminated seawater. A more detailed description of one of the oxidation pond systems 242 will be given hereinafter with reference to Figure 5b.

The contaminated seawater can be transferred from the oxidation pond system 242 to a basification tank 250 as appropriate via a fluid connection overflow 248. The alkaline storage tank 252 is configured to supply alkaline agent to the basin 250 via the fluid connection tube 254 as appropriate. The alkaline agent can be, for example, limestone or fresh seawater from the ocean, which is used to increase the pH of the contaminated seawater as needed.

Finally, the contaminated seawater is returned to the ocean 236 from the alkalizing tank 250 via a fluid connection overflow 256.

According to an alternative embodiment, the contaminated seawater that is transferred via the overflow pipe 248 is directly transferred to the ocean 236 without passing through any alkalizing tank. According to another alternative embodiment, the contaminated seawater is mixed with fresh seawater before being discharged into the ocean 236. To this end, a tube 251 can be fluidly coupled to the pressure tube 238 to transfer a stream of fresh sea water to the fluid connection overflow tube 248. Therefore, fresh seawater is mixed with one of the polluted seawater in the tube 248.

Figure 6b shows the oxidation cell system 242 in more detail. Polluted seawater via oxidation pond A fluid at one of the first ends 258 (which is an "inlet end") is connected to the oxidation tube 240 and supplied to the oxidation cell 243 of the oxidation pond system 242. The contaminated seawater flows from the first end 258, along the length LB of the oxidation pond 243 (as indicated by arrow S), to a substantially horizontal flow to one of the second ends 260 of the oxidation pond 243 (which is an outlet end). At the second end 260, the contaminated seawater overflows into the fluid connection overflow tube 248 and exits from the pool 243.

Oxidation cell system 242 further includes an oxygen supply system 247 having a piping system 246. Piping system 246 includes a central dispensing tube 262 that extends horizontally from one of the first ends 258, along the pool 243, to a position adjacent one of the second ends 260. The piping system 246 further includes first, second, third, fourth, fifth, and sixth continuous air distribution tubes 264, 266, 268, 270, 272, 274 that are fluidly coupled to the central distribution tube 262 and extend It flows through the contaminated seawater 275 of the pool 243 horizontally. The six air distribution tubes 264, 266, 268, 270, 272, 274 are continuously disposed along the length LB of the pool 243, wherein the first air distribution tube 264 is located closest to the first end 258 and the second air distribution tube 266 is located Downstream of first tube 264, etc., and sixth air distribution tube 274 is located closest to second end 260. Each of the air distribution tubes 264, 266, 268, 270, 272, 274 has a respective control device in the form of a control valve 276, 278, 280, 282, 284, 286 that can be controlled to control the passage of the respective air The flow rate of the oxygen-containing gas (such as air) of the pipes 264, 266, 268, 270, 272, 274. The blower 244 blows air into the central distribution tube 262 and further into the air distribution tubes 264, 266, 268, 270, 272, 274. The lower ends 288 of the air distribution tubes 264, 266, 268, 270, 272, 274 are open and disposed in oxygen Below the liquid surface 290 of the contaminated seawater 275 in the chemistry pool 243. Air blown by the blower 244 is transferred to the open lower end 288 via the central distribution tube 262 and the air distribution tube. At the open end 288, the air is dispersed and mixed with the contaminated seawater. Thus at least a portion of the oxygen content of the air dispersed and mixed with the contaminated seawater is dissolved in the contaminated seawater and reacts to oxidize the sulfite and/or bisulfite ions according to the reactions described below.

According to an alternative embodiment, the oxygen supply system 247 is operable to blow one of the oxygen-rich gas including 21% by volume or more of oxygen (for example, it includes 75 to 100% by volume of oxygen) into the contaminated seawater in the oxidation tank 243. .

The oxidation pond system 242 can further include first, second, third, fourth, and fifth continuous water quality sensors 292, 294, 296, 298, 300 that are immersed in the contaminated seawater 275 flowing through the pool 243. . The five water quality sensors 292, 294, 296, 298, 300 are continuously disposed along the length LB of the pool 243, wherein the first water quality sensor 292 is located closest to the first end 258, and the second water quality sensor 294 is Located downstream of the first sensor 292, etc., and the fifth sensor is located closest to the second end 260. A sixth and last water quality sensor 302 is disposed in the overflow tube 248. Each water quality sensor 292, 294, 296, 298, 300, 302 can include one or more detection elements. In the embodiment illustrated in FIG. 5b, each water quality sensor includes a sulfite detecting element 304, an oxygen detecting element 306, and a pH detecting element 308. The sulfite detecting element 304 includes a sulfite sensor 1.

Each water quality sensor 292, 294, 296, 298, 300, 302 is configured to detect one or more parameters of the contaminated seawater (as measured in a particular location in which the associated water quality sensor is configured) and send a signal To a control unit 310. Control unit 310 (which may be a process control computer) analyzes signals received from respective water quality sensors 292, 294, 296, 298, 300, 302 and automatically controls respective control valves 276, 278, 280, 282, 284, 286 The setting is such that a suitable flow of oxygen-containing gas is supplied to the contaminated seawater via each of the air distribution pipes 264, 266, 268, 270, 272, 274. Control unit 310 can also automatically control the output of blower 244 such that a suitable amount of air is supplied to piping system 246 and further to air distribution tubes 264, 266, 268, 270, 272, 274.

While the invention has been described with respect to the preferred embodiments embodiments illustrated embodiments In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the scope of the invention. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed, Moreover, the use of the terms first, second, etc. does not mean any order or importance. Instead, the terms first, second, etc. are used to distinguish the elements.

1‧‧‧ sulfite sensor

2‧‧‧Shell

3‧‧‧ Space

4‧‧‧Base section

10‧‧‧Sensor head

10a‧‧‧Internal

11‧‧‧First electrode

12‧‧‧ surface

13‧‧‧Axial end section

20‧‧‧second electrode

30‧‧‧grinding unit/cleaning unit

31‧‧‧Axis

32‧‧‧ Surface

40‧‧‧Control unit

50‧‧‧Analysis unit

60‧‧‧temperature sensor

101‧‧‧ Wet scrubber

102‧‧‧Vertical open tower

104‧‧‧ Entrance

106‧‧‧Export

108‧‧‧absorbing liquid storage tank

109‧‧‧ bottom

110‧‧‧Oxidation configuration

112‧‧‧Oxygen supply unit / blower

112a‧‧‧Blowers

114‧‧‧Oxygen distributor

116‧‧‧Nozzles

118‧‧‧Distribution tube

120‧‧‧Supply tube

122‧‧‧Absorbent supply system

124‧‧‧ limestone storage silos

126‧‧‧Fluid connection supply tube

128‧‧‧Mixed storage tank

130‧‧‧Agitator

132‧‧‧Limestone supply pipe

134‧‧‧Washer circulation pump

136‧‧‧absorbing liquid circulation pipe

138‧‧‧ spray level system

140‧‧‧Spray level system

142‧‧‧Pipe system

144‧‧‧Fluid connection spray nozzle

146‧‧ ‧ mist eliminator

148‧‧‧Disposal tube

150‧‧‧Band filter

152‧‧‧Control unit

154‧‧‧absorbent sampling system

156‧‧‧Direct sampling device

158‧‧‧Accumulating liquid storage tank sampling device

160‧‧‧ Collector

162‧‧‧ surface

164‧‧‧Fluid connection tube

166‧‧‧First pH Analyzer

168‧‧‧First Sulfite Analyzer

170‧‧‧ tube

172‧‧‧Second pH Analyzer

174‧‧‧Second sulfite analyzer

176‧‧‧Circulation tube

178‧‧‧Circulating pump

180‧‧‧Close valve

182‧‧‧Close valve

184‧‧‧Close valve

186‧‧‧Sampling tube

188‧‧‧Close valve

190‧‧‧Control valve

192‧‧‧First SO ₂ Analyzer

194‧‧‧Second SO ₂ analyzer

195‧‧ Export

196‧‧‧ funnel section

197‧‧‧ bottom

199‧‧‧Drainage tube

201‧‧‧Power Plant

202‧‧‧Boiler

204‧‧‧ Feeding tube

206‧‧‧Oxygen supply tube

208‧‧‧Fluid connection tube

210‧‧‧Electrostatic dust collector

212‧‧‧Fluid connection tube

214‧‧‧Seawater scrubber

216‧‧‧Wet scrubber tower

218‧‧‧ entrance

220‧‧‧下下

222‧‧‧ Internal

224‧‧‧Central Part

226‧‧‧ spray configuration

228‧‧‧Supply tube

230‧‧‧ nozzle

232‧‧‧ pump

234‧‧‧ fluid connection straw

236‧‧‧The ocean

238‧‧‧pressure tube

239‧‧‧ Filling materials

240‧‧‧ fluid connection sewage pipe

242‧‧‧Oxidation Pool System

243‧‧‧Oxidation Pool

244‧‧‧Blowers

246‧‧‧Pipe system

247‧‧‧Oxygen supply system

248‧‧‧Fluid connection overflow pipe

249‧‧‧ tube

250‧‧‧Basification tank

251‧‧‧ tube

252‧‧‧ storage tank

254‧‧‧Fluid connection tube

256‧‧‧Fluid connection overflow pipe

258‧‧‧ first end

260‧‧‧ second end

262‧‧‧Central distribution tube

264‧‧‧First air distribution tube

266‧‧‧Second air distribution tube

268‧‧‧ Third air distribution tube

270‧‧‧fourth air distribution tube

272‧‧‧ fifth air distribution tube

274‧‧‧ sixth air distribution tube

275‧‧‧Contaminated seawater

276‧‧‧Control valve

278‧‧‧Control valve

280‧‧‧Control valve

282‧‧‧Control valve

284‧‧‧Control valve

286‧‧‧Control valve

288‧‧‧open the lower end

290‧‧‧ liquid surface

292‧‧‧First water quality sensor

294‧‧‧Second water quality sensor

296‧‧‧The third water quality sensor

298‧‧‧Fourth water quality sensor

300‧‧‧ fifth water quality sensor

302‧‧‧ sixth water quality sensor

304‧‧‧ sulfite detection component

306‧‧‧Oxygen detection element

308‧‧‧pH detection component

310‧‧‧Control unit

1 is a perspective view of a sulphite sensor in accordance with an embodiment.

Figure 2 is a schematic side cross-sectional view of one of the sulfite sensors.

Figure 3 is a flow chart of one of the methods for measuring sulfite in a substance.

4a is a graph of voltage levels from a method over time, in accordance with an embodiment.

Figure 4b is one of the voltage level pulses from a method in accordance with an embodiment Simulation map.

Figure 4c is a simulation of one of the voltages corresponding to a current response generated by the voltage pulse in Figure 4b.

Figure 5a is a schematic side cross-sectional view of one of the wet scrubbers including a sulfite sensor.

Figure 5b is an enlarged schematic side cross-sectional view of one of the collectors according to an alternative embodiment.

Figure 6a is a schematic side cross-sectional view of one of the power plants having one of the gas purification systems based on seawater.

Figure 6b is a schematic side cross-sectional view of one of the oxidation cell systems in a gas purification system.

1‧‧‧ sulfite sensor

2‧‧‧Shell

3‧‧‧ Space

4‧‧‧Base section

10‧‧‧Sensor head

10a‧‧‧Internal

11‧‧‧First electrode

12‧‧‧ surface

13‧‧‧Axial end section

20‧‧‧second electrode

30‧‧‧grinding unit/cleaning unit

31‧‧‧Axis

40‧‧‧Control unit

50‧‧‧Analysis unit

60‧‧‧temperature sensor

Claims (14)

A method (80) for measuring a concentration of sulfite in a substance in a gas purification process, the method comprising the steps of: (82) transmitting through a first electrode (11) and a second electrode (20) Transmitting a plurality of voltage pulses, the first and second electrodes (11, 20) are in contact with the substance; (84) receiving a current response generated by the plurality of voltage pulses; and (86) using a multivariate Data analysis was performed to analyze the current responses to calculate the sulfite concentration in the material. The method of claim 1, wherein the step (82) of transmitting the plurality of voltage pulses comprises transmitting the plurality of voltage pulses in the series to gradually increase and/or decrease the voltage level. The method of claim 1, wherein the step (86) of analyzing the current responses comprises analyzing the peaks of the current responses using multivariate data analysis. The method of claim 1, wherein the value of each voltage pulse transmitted through the substance is 0.02 volts to 0.2 volts higher or lower than the previous adjacent voltage pulse. The method of claim 1, wherein the step (86) of analyzing the current responses comprises analyzing the peak of one of the current responses and at least another value using multivariate data analysis. The method of claim 1, wherein the method further comprises cleaning a surface (12) of the first electrode (11) to remove a coating caused by contact between the first electrode (11) and the substance. The method of claim 6, wherein the surface (12) of one of the first electrodes is cleaned This step includes rotating a cleaning unit (30) into contact with the first electrode (11). The method of claim 7, wherein the cleaning unit (30) is rotated to contact the surface (12) of one of the first electrodes (11) at a rate of 2 revolutions per minute to 40 revolutions per minute. The method of any of the preceding claims, wherein the substance is one of the absorbing liquids used in a wet scrubber purification process. A sulfite sensor (1) for measuring a concentration of sulfite in a substance in a gas purification device, wherein the sulfite sensor comprises: a first electrode (11) and a second electrode (20), which is adapted to be in contact with the substance; a control unit (40) adapted to transmit a voltage pulse by the first electrode (11) and the second electrode (20) transmitting the substance; And an analysis unit (50) adapted to receive and analyze a current response generated by the voltage pulses, wherein the analysis unit is adapted to perform a multivariate data analysis to calculate the sulfite concentration in the substance. A sulfite sensor as claimed in claim 10, wherein the control unit (40) is adapted to transmit the voltage pulses in the series such that one of the voltage pulses is gradually increased and/or subtracted by the transmitted voltage level. small. A sulfite sensor as claimed in claim 10, wherein the analysis unit (50) is adapted to perform a multivariate data analysis based on peaks of the current responses. The sulfite sensor of any one of claims 10 to 12, wherein the sulfite sensor (1) further comprises an adaptation to clean the first electrode (11) One of the cleaning units (30). The sulfite sensor of claim 13, wherein the first electrode (11) is a ring electrode, and wherein the cleaning unit (30) is in contact with the annular first electrode (11) and is adapted to rotate and clean One surface (12) of the ring electrode (11).