JP2943162B2 - Method and apparatus for measuring lime concentration in slurry absorbent for flue gas desulfurization - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for continuously measuring the concentration of a specific substance in a slurry for measuring the lime concentration and the like of an absorbent used in a wet desulfurization apparatus, and an apparatus therefor.

[Related Art] In general, in a wet type de-flow device provided in a coal-fired boiler or the like, exhaust gas is desulfurized using a slurry-like absorbent.

As shown in FIG. 4, a conventional wet desulfurization apparatus 1 of this kind
After the exhaust gas discharged from the boiler 2 is once cooled and dust-removed, the exhaust gas is contact-reacted with an absorbing solution of lime (calcium carbonate, CaCO ₃ ) circulated by a circulator 4 in an absorption tower 3 and then reacted with air. To be released.

The lime powder, which is a raw material of the absorbing liquid, is supplied to the absorption tower 3 in the charging section 5 having a hopper or the like, and the gypsum (CaSO ₄ ) generated by the reaction is separated by another route. It is to be collected.

[Problems to be Solved by the Invention] By the way, in order to carry out the desulfurization reaction in the best condition corresponding to the operating conditions of the boiler 2 and the like, it is necessary to constantly control the concentration of the absorbing solution.

However, since the absorbing solution contains solids such as gypsum, calcium sulfite (CaSO ₃ ), coal ash, and unburned matter, in addition to poorly soluble lime, lime is extracted and quantitative analysis is performed. It was difficult and time-consuming.

For example, if the solid component was quantitatively analyzed by a chemical method except for the water in the absorbing solution, a period of about one day was required, and the problem of measuring the concentration in real time could not be met.

In view of the above circumstances, the present invention has been devised in order to provide a method and apparatus capable of rapidly and continuously measuring the lime concentration of a slurry absorbing solution.

[Means for Solving the Problems] A first aspect of the present invention relates to a method for measuring lime concentration in a slurry absorbing solution when desulfurizing exhaust gas and slurry absorbing solution in gas-liquid contact in an absorption tower. Forming a sample cell for introducing the slurry absorbing solution around the cylindrical inner reflector, injecting the slurry absorbing solution in the absorption tower into the sample cell and uniformly stirring the same, An infrared ray is incident on one side, and the infrared ray reflected entirely on the inner surface of the internal reflector is extracted on the other side to extract the absorption spectrum of the slurry absorbing solution, and the density of the slurry in the slurry absorbing solution is measured by a densitometer. The intermittent calculation of the concentration of lime in the slurry absorbing liquid is performed on the basis of the above, and washing is performed by spraying fresh water onto the surface of the inner reflector in the sample cell.

In addition, the second aspect of the present invention is a device for measuring the lime concentration in the slurry absorbing liquid when the exhaust gas and the slurry absorbing liquid are brought into gas-liquid contact in the absorption tower to measure the lime concentration in the slurry absorbing liquid. Infrared spectroscopy that has a sample cell around which the slurry absorbing liquid is introduced, and which receives infrared light from one of the internal reflectors and extracts infrared light that has been totally reflected from the internal reflecting body and extracts the absorption spectrum of the slurry absorbing liquid A photometer, a slurry stirring means for injecting the slurry absorbing solution in the absorption tower into the sample cell and uniformly stirring the same, a density meter for measuring the slurry density in the slurry absorbing solution, and the density and the absorption spectrum. The apparatus includes an arithmetic processing unit for intermittently calculating the concentration of lime in the slurry absorbing liquid, and a washing means for washing by spraying fresh water onto the surface of the inner reflector in the sample cell.

[Operation] By the above method, the content of lime in the solid component of the slurry is detected from the detected spectral intensity of lime,
By taking into account the density of the solid component in the slurry at that time, the concentration of lime is calculated intermittently. Thereafter, the surface of the inner reflector is washed and the slurry absorbing liquid is removed, so that the lime concentration can be continuously measured.

Further, with the above configuration, the infrared spectrophotometer repeatedly reflects the infrared light on the inner surface of the inner reflector, and performs component analysis of the slurry absorbing liquid around the inner reflector. The stirring means uniformly distributes the slurry absorbing liquid flowing into the sample cell around the internal reflector. The arithmetic processing unit extracts a spectrum for which a predetermined wavelength is obtained in advance, integrates and analyzes the intensity, and calculates the lime concentration from the slurry density measured by the densitometer. The cleaning means cleans the surface of the internal reflector after calculating the concentration.

Embodiment First, the principle of the total reflection absorption measurement method (ATR method) according to the present invention will be described with reference to FIG.

Various methods are known for determining the components in a sample based on the transmission spectrum of the reflected light.In the ATR method, instead of the air-sample surface of the normal reflection spectrum, the sample and the red having a higher refractive index are used as the reflection surface. A transparent butterfly is used in the outer region, and the incident angle θ is set to be larger than the critical angle θe so that total reflection occurs at the medium-sample interface.

In FIG. 3, assuming that the refractive indexes of the touch substance (ATR crystal) A and the sample B are n ₁ and n ₂ , the critical angle θe is represented by the following equation.

Looking at the state of the total reflection microscopically, the light is not reflected at the interface but is totally reflected after entering the sample B side by a certain depth dp. At this time, the light is totally reflected in the wave number region where the sample B does not absorb light, but is not completely reflected in the region where the light is absorbed, but the intensity of the totally reflected light decreases according to the intensity of the absorption. Therefore, if this reflection energy is measured, a total reflection spectrum similar to the transmission spectrum can be obtained.

 Next, examples of the present invention will be described.

First, referring to FIG. 1, one embodiment of a device for measuring the concentration of a specific substance in a slurry according to the present invention will be described. In this embodiment,
This shows a case where the present invention is applied to a desulfurization apparatus 1 provided in a coal-fired boiler or the like, in which the concentration of lime (calcium carbonate) as a specific substance in an absorption liquid of a desulfurization apparatus as a slurry is measured.

This measuring apparatus includes an infrared spectrophotometer 13 having a sample cell 11 into which the absorbing liquid S is injected, an inner reflector 12 set in the sample cell 11, and a stirring means 14 provided in the sample cell 11.
And a densitometer 15 for measuring the density of the absorbing solution S, and an arithmetic processing unit 16 for calculating the lime concentration based on the information of the densitometer 15 and the infrared spectrophotometer 13.

A known infrared spectrophotometer 13 analyzes an organic component in an aqueous solution by utilizing absorption of a specific vibration energy depending on a molecular structure when an infrared ray hits a substance (infrared spectroscopy). belongs to. The photometer 13 includes a light source device 17 for generating infrared rays R to the inner reflector 12,
A detector 18 is provided for receiving the infrared rays R emitted from the internal reflector 12 and transmitting the information to the arithmetic processing unit 16.

The inner reflector 12 is made of a substantially columnar hard crystal, and is provided along the optical path of the infrared ray R. Then, the infrared ray R that has entered from one end side is transmitted to its inner surface 19 and inner reflector
Is repeatedly reflected (multiple-reflected) on the analysis effective layer 20 near the outer periphery of the infrared ray, thereby giving the infrared ray R emitted from the other end side spectral information. That is, it is a "medium" for implementing the ATR method.

The sample cell 11 is formed of a shell that accommodates the absorbing liquid S in a closed state, and holds the inner reflector 12 at the center thereof. An absorption liquid injection pipe 21 and an absorption liquid discharge pipe 22 branched from a circulation path 4 provided in the absorption tower 3 of the desulfurization device 1 are provided radially outward of the inner reflector 12 which is a side portion thereof. The connected and circulating absorbing solution S can be introduced into the sample cell 11.

The injection port 23 and the spout 24, which are connection portions with the injection pipes 21 and 22, are formed so as to be deviated in the opposite directions from the center of the sample cell 11. In the middle of the absorbing liquid injection pipe 21, a pump 25 for giving a predetermined flow rate to the absorbing liquid S is provided. That is, the injected absorbing liquid S forms a swirling flow, and the injection outlets 23 and 24 and the pump 25 form the stirring means 14.

The arithmetic processing unit 16 extracts the lime spectrum from the infrared absorption spectrum received by the detector 18, calculates (integrates) the intensity based on the peak area, and converts the intensity into the ratio of solid components. It has become. And
From the density (specific gravity) of the absorbing solution at that time, the lime concentration (% by weight) in the absorbing solution is calculated and displayed.

In addition, a cleaning means 26 for cleaning dirt on the surface is provided near the inner reflector 12. The cleaning means 26 includes a plurality of nozzles 27 provided facing the outer periphery of the inner reflector 12, and a pipe 28 for guiding fresh water to the nozzles 27.
By intermittently ejecting fresh water, the optical soundness of the inner reflector 12 is maintained.

A switching valve 29 is provided at the connection between the circulation path 4 and the injection / exhaust pipes 21 and 22, and can be continuously opened or closed to measure the concentration of the absorbing solution S continuously or as needed. It has become.

Next, an embodiment of a method for measuring the concentration of a specific substance in a slurry according to the present invention will be described as an operation of the above embodiment.

As shown in FIG. 2, first, a standard absorption solution containing only lime is prepared, injected into the sample cell 11, and the wavelength of the infrared absorption spectrum is measured. Store it in 16. (See FIG. 2 (a).) Then, by operating the switching valve 29, a part of the absorption liquid S circulating in the sample cell 11 is transferred to the sample cell 11 via the absorption liquid injection pipe 21.
At the same time, the pump 25 is operated and pressurized,
A swirling flow around the longitudinal axis of the inner reflector 12 is formed.

In this state, the infrared spectrophotometer 13 is operated. That is,
By emitting infrared rays R from the light source device 17 and making multiple reflections on the inner reflector 12, the absorption spectrum of the absorbing liquid S in the analysis effective layer 20 on the outer periphery is detected.

The arithmetic processing unit 16 extracts a spectrum of the corresponding wavelength, that is, an absorption spectrum of lime (calcium carbonate) from all the detected spectra, integrates the intensities thereof (see FIG. 2 (b)), and furthermore, the absorption liquid S Calculate the solid component ratio in the inside.

On the other hand, the density meter 15 measures the density of the absorbing solution S in the process of returning to the circulation path 4 from the sample cell 11 by the absorbing solution discharging pipe 22, and inputs the measured value information to the arithmetic processing device 16.

Then, the arithmetic processing unit 16 calculates the lime concentration in the absorbing solution S from the spectrum intensity and the density, and displays the data.

As described above, the present invention is characterized in that the concentration of a specific substance in a slurry can be measured accurately and in real time by combining the photometer of the ATR method and the infrared spectroscopy. That is, an infrared spectrophotometer provided with the internal reflector 12
Since 13 sample cells 11 were provided with a stirring means 14 and a densitometer 15 for always making the mixed state of the slurry around the inner reflector 12 uniform, the lime concentration was measured by an infrared absorption spectrum. The lime concentration in the circulating absorbent S is immediately known, and can be continuously measured only by operating the switching valve 29. That is, quick and continuous absorption liquid management can be performed, and it is possible to contribute to realizing the best control of the desulfurization device 1.

The provision of the stirring means 14 can prevent non-uniformity (sedimentation or stagnation) around the inner reflector 12. That is, measurement according to the slurry characteristics of the absorbing solution S has become possible.

It is desirable that the hard material of the inner reflector is made of a material that is not worn by the absorbing liquid, for example, germanium. Specifically, a cylindrical crystal for liquid used in an ATR apparatus may be applied.

Further, any stirring means may be used as long as it provides a swirling flow, and a rotating blade or the like may be provided in the sample cell.

Further, as the cleaning means, in addition to the water jet as in the present embodiment, an ultrasonic wave may be formed along the outer periphery of the inner reflector 12, or may be cleaned with an acid.

[Effects of the Invention] In summary, according to the invention of the present method and apparatus, an absorption spectrum of a slurry can be obtained by infrared rays that are multiple-reflected on an internal reflector, and the concentration of a specific substance in the slurry can be measured quickly and continuously. It has an excellent effect of being able to do it.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the apparatus for measuring the concentration of a specific substance in a slurry according to the present invention, and FIG. 2 is an embodiment of a method for measuring the concentration of a specific substance in a slurry according to the present invention. FIG. 3 is a conceptual diagram for explaining the principle of the ATR method, and FIG. 4 is a block diagram showing a wet de-flow device of a boiler for explaining a conventional technique. In the figure, 11 is a sample cell, 12 is an internal reflector, 13 is an infrared spectrophotometer, 14 is a slurry stirring means, 15 is a density meter, 16 is a processing unit, and S is a slurry absorbing liquid.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01N 21/00-21/61 G01N 21/84-21/89

Claims (2)

(57) [Claims] In a method for measuring the lime concentration in an exhaust gas and a slurry absorbent in a gas-liquid contact with the exhaust gas and a slurry absorbent in an absorption tower, a slurry is provided around a cylindrical inner reflector. A sample cell for introducing the absorbing liquid is formed, and the slurry absorbing liquid in the absorption tower is injected into the sample cell and uniformly stirred. On the other hand, infrared rays are incident from one of the internal reflectors and the internal reflection is performed on the other. Extract the infrared spectrum that is totally reflected inside the body, extract the absorption spectrum of the slurry absorption solution, measure the slurry density in the slurry absorption solution with a densitometer, and intermittently determine the lime concentration in the slurry absorption solution from the density and absorption spectrum. A method for measuring the lime concentration in a slurry absorption solution for flue gas desulfurization, wherein the lime concentration is calculated and the surface of the inner reflector in the sample cell is washed by spraying fresh water. 2. An apparatus for measuring the lime concentration of an exhaust gas and a slurry absorbing liquid in gas-liquid contact in an absorption tower to measure the lime concentration in the slurry absorbing liquid. An infrared spectrophotometer that has a sample cell for introducing the absorbing liquid, emits infrared light from one of the internal reflectors, extracts infrared light that is totally reflected on the internal reflecting body on the other side, and extracts the absorption spectrum of the slurry absorbing liquid, A slurry stirring means for injecting and uniformly stirring the slurry absorbing solution in the absorption tower into the sample cell, a density meter for measuring a slurry density in the slurry absorbing solution, and a density meter for measuring the slurry density in the slurry absorbing solution. A flue gas desulfurization slurry, comprising: an arithmetic processing device for intermittently calculating the concentration of lime of the present invention; and washing means for spraying fresh water onto the surface of the inner reflector in the sample cell for washing. Lime concentration of the measuring device in Osamueki.