JPS59142461A - Method for measuring continuously of calcium sulfite concentration - Google Patents

Abstract

PURPOSE:To measure continuously and automatically CaSO3 in a slurry by letting the slurry flow continuously into a reaction vessel in the absence of air, maintaining the quantity of the slurry at a constant state, blowing an oxygen- contg. gas into the slurry and measuring the difference of each O2 concentration between a gas before blowing and an exhaust gas. CONSTITUTION:When measuring the concentration of CaSO3 in a slurry in an SO2 absorbent or the like of a wet desalting and desulfurization apparatus, the slurry to be measured is put in a reaction vessel 1 through a piping 6 and the slurry level in the vessel 1 is maintained constant by flowing out the overflowed slurry through a piping 4. A gaseous mixture of N2 and O2 is blown through holes 16 of a pipe 8 to oxidize CaSO3 to CaSO4. The gaseous mixture brought into contact with the slurry is exhausted from a pipe 10. Each O2 concentration in the blowing gaseous mixture and the exhaust gas is measured respectively by analizers 9, 11 and the CaSO3 concentration in the slurry is shown on an indicator 17 by calculating the difference of each O2 concentration using a prescribed relative equation by a calculator 15. In this manner, the concentration can be measured automatically and continuously.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for continuously measuring the concentration of calcium sulfite in a slurry such as So, absorption liquid, etc. of a wet flue gas desulfurization device.

Conventionally, there has been no method to continuously measure calcium sulfite concentration, and it has been necessary to rely on manual analysis, which has the disadvantage of being labor-intensive and time-consuming.

Therefore, the present inventors conducted various studies to eliminate the drawbacks of conventional manual analysis, and finally completed the present invention.

That is, the present invention allows slurry to continuously flow into a reaction vessel that is kept fresh from the atmosphere, adjusts the amount of slurry flowing out from the reaction vessel, keeps the amount of slurry in the reaction vessel constant, and further increases the amount of slurry in the reaction vessel. An oxygen-containing gas such as air or a mixed gas of an inert gas and oxygen (containing no other components reactive with calcium sulfite) is blown into the slurry, and the slurry and the mixed gas are brought into contact with each other. The present invention relates to a method for measuring the concentration of calcium sulfite in a slurry, which is characterized by calculating the concentration of calcium sulfite in the slurry from the oxygen concentration before and after contact.

In the method of the present invention, (1) if the oxygen concentration before contact is unknown, measure the oxygen concentration at two locations, before and after contact;
Calculate the calcium sulfite concentration in the slurry from these two measured values, (2) If the oxygen concentration before contact is known, measure the oxygen concentration after contact, and from the measured value, calculate the calcium sulfite concentration f in the slurry: calculate.

A practical example of the present invention applied to SO and absorption slurry in a wet flue gas desulfurization device will be specifically described with reference to FIG. The slurry to be measured flows into the reaction vessel 1 through the pipe 6, and then flows into the reaction vessel 1 through the pipe 4.
The amount of slurry in the reaction vessel 1 is controlled to be constant by allowing more overflowed slurry to flow out. Piping 4 is inserted below the slurry level in vessel 5, refreshing reaction vessel 1 with atmosphere. Note that the inflow slurry flow rate is controlled to a constant flow rate by a flow rate detection controller 7 and a control valve 18. A mixed gas of nitrogen and oxygen is blown into the slurry in the reaction vessel 1 through the piping 8 and the gas blowing hole 16, and brought into contact with the slurry. At this time, if calcium sulfite is present in the slurry, the following reaction will occur.

Ca803→Ca"+803"-(1)F303"--
1-4o, -) So-" □ (21Ca"" +
Oxygen in the gas is consumed by the reaction of the formula SQ, "-→CaSO4-13112). Since the reaction occurs at a ratio of 1 mole of oxygen to 2 moles of calcium sulfite from the reaction of the formula 11r21131, the concentration of calcium sulfite Oxygen is consumed proportionally.The gas that has come into contact with the slurry passes through the pipe 10 to the outside of the system.

The oxygen-containing gas to be blown is detected by a flow rate detection controller 19 and a control valve 2.
0, the flow rate is controlled to be constant.

The slurry in the reaction vessel 1 is stirred by an agitator drive motor 2 and an agitator 5. When the slurry is SQ or absorption liquid for wet flue gas desulfurization equipment, the slurry contains a small amount of carbon ions, and when it comes into contact with a mixed gas of nitrogen and oxygen, the following reaction occurs, resulting in CO8"-+2H −→F(, O+CO, ↑ (
4) Carbon dioxide is released into the gas mixture. At this time, pH increases because hydrogen ions are consumed. When p[( increases, the dissolution reaction of calcium sulfite in equation (1) progresses, and as a result, the oxidation reaction rate in equation (2) worsens. To keep the oxidation reaction rate constant, pF( Therefore, sulfuric acid is flowed into the reaction vessel 1 from the pipe 12, and the pH is kept constant by a pH detection controller 15 and a control valve 14.An inlet oxygen analyzer is installed in the pipes 8 and 10. 9 and an outlet oxygen analyzer 11 are provided to measure the respective oxygen concentrations, and input the measurement signals to a calculator 15.The calculator 15 performs the following calculations.

xl: Measured oxygen concentration of inlet oxygen analyzer 9 (%1x,: ?l!Iln elementary concentration of Ichihiro oxygen analyzer 11 (dry) K: Constant Y: Calcium sulfite concentration (m-mol/L)
(Equation 51 was derived as follows. The flow rate of the slurry flowing into the reaction vessel 1 per unit time is L(Z/II(l), the concentration of calcium sulfite contained in the slurry y (+
Assuming that n-mol/41 and the oxidation reaction rate is α, the amount of calcium sulfite that is oxidized to become gypsum Z' (m-m
ol/old is Z=α・L, Y(6) and potash, the oxygen required at this time Ji Z' (m −mo
Since the molar ratio is l/Hl, oxidized calcium sulfite may be used, so zl = jiα · L-7(a). On the other hand, if the flow rate of the mixed gas of nitrogen and oxygen blown into the reactor 1 is F(N-6/F(), the amount of oxygen per unit time A (m-mat/H) is The amount AJm-mol/H1 is expressed by equation (8), (γ)
From the formula, the amount of nitrogen exiting from the pipe 10 c (m-mol/
Since H1 remains unchanged, the oxygen concentration x, (chi-dry) in the pipe 10 is defined by the aυ equation from equation (9). Note that the amount of Co generated within the reactor is very small, so it will be ignored.

X, 1000 1 Transforming the 09 formula into a formula for determining y, 000 F·□ If we set 000 F·□ 22.4 in the formula of a, the 63 formula becomes the formula (5). In formula I, the nitrogen and oxygen mixed gas flow rate F1 slurry flow rate is controlled to be constant by a slurry flow rate detection controller 7 and a gas flow rate detection controller 19, and the fermentation reaction rate α is controlled to be pf by a pH controller 15. Since ( is controlled to be constant, it can be regarded as constant. Therefore, K in the aJ formula is considered to be a constant and is set in the calculator 15 in advance.The calculator 15 calculates the formula (5), The calculation result y is displayed on the indicator 17.

In this way, it became possible to measure calcium sulfite concentration continuously.

To give a concrete explanation using numerical values, O slurry flow rate L = 1.0 (t, /H1O mixed gas flow rate of air and oxygen F = 2 o (N-1/a
)0 oxidation reaction rate α=0.9 − Xo, 9X1.0 To simplify the explanation, inflow mixed gas oxygen concentration xl=2
If it is constant at 0%, the relationship between the outflow mixed gas oxygen concentration For the known field &, as shown in Fig. 5, it is only necessary to input only the oxygen concentration of the outflow mixed gas into the calculator 15, but in that case, the calculation becomes 0O-x2, Ko: a constant, and K is (13 The number determined by the formula is the oxygen concentration of the incoming mixed gas (for example, K in the case of air), which is known to KO.
21.0) in the arithmetic unit in advance.

In addition, as a method of keeping the slurry amount in the reaction vessel 1 constant, an overflow method was used in the embodiments shown in FIGS. Other methods may be used as long as the amount of slurry is kept constant.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing one embodiment of the present invention, FIG. 2 is a graph showing the relationship between the oxygen concentration of the outflow mixed gas and the calcium sulfite concentration in one example of the present invention, and FIG. It is an explanatory view showing one example when oxygen concentration is known. Sub-agents 1) Meifuku agent Ryo Hagiwara - Figure 2

Claims (1)

[Claims] Continuous VC flow of slurry into a reaction vessel called atmospheric,
While keeping the amount of slurry in the reaction vessel constant, oxygen-containing gas is blown into the slurry to bring the slurry into contact with the oxygen-containing gas, and the calcium sulfite concentration in the slurry is determined from the oxygen concentrations in the oxygen-containing gas before and after contact with the slurry. A method for measuring calcium sulfite concentration in a slurry, the method comprising: calculating the concentration of calcium sulfite in a slurry.