JPS59204763A - Measurement of sulphur trioxide in exhaust gas - Google Patents

Abstract

PURPOSE:To enable continued measurement by allowing exhaust gas to pass through a hydrogen iodide filled convertor and detecting a concentration sulphur trioxide in exhaust gas by decrement of measurement hydrogen iodide in entrance and exit of the convertor. CONSTITUTION:Exhaust gas 1 containing SO3 and moisture is introduced to a sampling pipe as sampling gas 2 and then, a portion of the gas is introduced to a convertor 3 containing sodium iodide and other portion to an analyzer 10 of hydrogen iodide via the sampling tube 9. In the analyzer 10 a concentration of hydrogen iodide of gas 1 is measured. The gas introduced in the convertor 3 generates hydrogen iodide of doubled equivalent weight to SO3 according to the chemical terminal here. Temperature of the convertor is kept in a range 300- 400 deg.C suited to the reaction by a convertor heater 4. Gas from the convertor is introduced to a hydrogen iodide analyzer 6 through 4 a conduit pipe 5 and exhausted into air as hydrogen iodide analyzer discharge gas 7. 1/2 of the difference of analysis measurements of hydrogen iodide analyzer 10 and that of 6 is defined as the concentration of SO3.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to the treatment of sulfur trioxide (hereinafter referred to as 803) in gas containing sulfur trioxide, such as gas discharged from exhaust gas generating sources such as boilers! 1: Concerning a method for continuously measuring degrees.

In line with regulations on the total amount of sulfur oxides, the concentration of sulfur oxides in exhaust gas emitted from various exhaust gas sources has been reduced by using low-sulfur fuel and installing flue gas desulfurization equipment, and at the same time, the concentration of SO3 has also decreased to a trace level. It is becoming. However, when installing denitrification equipment, air preheaters, etc. at these exhaust gas generation sources, accurate understanding of SO2 concentration is one of the important items in equipment design such as equipment materials.

Conventionally, the method for analyzing So3 in exhaust gas has not been established in the Japanese Industrial Standards (JS), and the method used is to collect Jso3 using the 803 collection flow shown in Figure 1 and analyze it as sulfate ions using a prescribed method. Generally known. (Special application 1973
-49722) In this conventional method, the sample gas collected from the sampling tube is cooled to about 110°C, which is below the dew point of sulfuric acid and above the boiling point of water, and gaseous SO2 is made into a mist. These methods include collision, adhesion, or collection in a dust filter.

In FIG. 1, the exhaust gas flows through the flue 1 in the direction shown. A dust filter 4 is connected to collect the sample exhaust gas from the collection tube 2 heated by the heater 3, and the bog is turned into a mist in the spiral tube 7 disposed in the glycerin bath 9 kept at 110°C. Inertial collision, adhesion, or collection on membrane filter 8. This method has disadvantages in that it requires delicate know-how regarding the exhaust gas sampling temperature, cooling temperature, and passage speed through the spiral tube, requires skill in measurement, and cannot continuously measure the concentration.

The present invention was made to improve these drawbacks.
Rather than collecting So3 in the exhaust gas and chemically analyzing it as sulfate ions to measure the So3 concentration in the exhaust gas, the SOs and water contained in the exhaust gas are converted into a converter filled with sodium iodide (1 ) It is reacted with sulfuric acid as shown in the formula (2) and decomposed into IJium and hydrogen iodide.

801 (f) + H10 (f) + 2Na engineering (S) → Na2
804(S)+2E Engineering(f)-m-(Riko's reaction is performed by heating at 300-400°C.

Almost 100% So with an appropriate amount of sodium iodide.

is converted to hydrogen iodide. The hydrogen iodide concentration produced is measured by a continuous hydrogen iodide analysis instrument, making it possible to continuously measure S03. The present invention will be explained below with reference to Examples.

[Example 1] Fig. 3 This is an example in which the present invention is applied to the case of measuring the SO3 concentration of the outlet gas of the economizer of a heavy oil-fired boiler.

80. The exhaust gas 1 containing water and water is led to a sampling pipe as a sampling gas 2.

Next, it is divided into two types: one is passed through a converter 5 filled with sodium iodide, and the other is passed directly through a sampling tube 9 to a hydrogen iodide analyzer 10. The analyzer 10 measures the hydrogen iodide concentration of the exhaust gas 1. Here, the gas passed through the converter 3 filled with sodium iodide is converted to 80% according to equation (1). twice the equivalent of hydrogen iodide is produced. The temperature of the converter is maintained by a converter heater 4 in a range of 300 to 400°C suitable for the reaction. Gas from the converter is passed through conduit 5 to a hydrogen iodide analyzer 6 and discharged to the atmosphere as hydrogen iodide analyzer exhaust gas 7. The difference K between the analysis values of the hydrogen iodide analyzer 10 and the hydrogen iodide analyzer 6 is taken as the EIO3 concentration of the exhaust gas 1.

In this method, if the hydrogen iodide concentration in the exhaust gas is almost negligible compared to the So3 concentration, the So3 concentration can be set as % of the hydrogen iodide concentration on the converter side, and one can be omitted.

Also, the caution with this method is that dust accumulates in the exhaust gas in the converter 3 and the reaction efficiency decreases over time, but the dust concentration in the combustion exhaust gas is 10 to 20 q/In3.803.
Continuous measurement is possible for approximately 1000 hours at a concentration of 1 to 10 ppm without replacing the filling (sodium iodide).

[Example 2] In applying Example 1, in order to find the converter 3 temperature (reaction temperature), the converter temperature was varied in the range of 200°C to 400°C, and the sampling gas amount and sodium iodide filling amount were changed. The SO3 measurement value was determined under constant conditions. The results are shown in Table 1.

As a result, almost the same results as manual analysis were obtained in the temperature range of 300°C to 400°C.
It was found that it was sufficient to maintain the temperature at 0°C.

Table 1 Test results Note that if the amount of sodium iodide filled in the converter 3 is small, sufficient reaction with So in the exhaust gas may not be obtained. ONt/mi
In order to determine the necessary amount of sodium iodide to be filled into the converter 3 at the time of n, the following experiment was conducted just to be sure.

The amount of sodium iodide charged was varied while keeping the converter temperature and sampling gas amount constant.

The measured value of So was determined. The results are shown in Table 2.

As a result, it was found that the collection tube should be planned under the conditions of experiment numbers 2 to 5.

Table 2 Test Results This is an example of the measurement of 803 in the exhaust gas of a dry flue gas denitrification device that injects ammonia as a reducing agent into heavy oil combustion exhaust gas according to the present invention. Dry flue gas denitrification equipment usually operates at 500℃~
It operates at a gas temperature of about 400℃. In this case, there is no need to measure the converter heater 4 and the hydrogen iodide concentration in the exhaust gas. The mode is shown in FIG.

As described above, the method for measuring EI03 in combustion exhaust gas of the present invention is extremely useful in practice.

[Brief explanation of drawings]

FIG. 1 is an explanatory schematic diagram of a conventional exhaust gas sampling device, and FIG. 2 is an explanatory front schematic diagram of the spiral tube with a menglan filter in FIG. 1. 6 and 4 are diagrams showing two specific embodiments of the present invention. Sub-agents 1) Meifuku agent Ryo Hagiwara -

Claims (1)

[Claims] A method for continuously measuring the concentration of sulfur trioxide in non-exhaust gas containing sulfur trioxide and water. The exhaust gas is filled with sodium iodide and passed through a converter, and the concentration of sulfur trioxide in the exhaust gas is detected based on the difference between the measured values of hydrogen iodide concentration at the inlet and outlet of the converter. Method for measuring sulfur trioxide concentration.