JPS61246515A - Detecting method and device for water concentration of exhaust gas in incinerator - Google Patents

Abstract

PURPOSE:To enable to find out water concentration in exhaust gas simply, exactly, continuously, and stably by detecting temp. and flow rate at an inlet and an outlet of a cooler respectively for exhaust gas sample which is sucked into the cooler. CONSTITUTION:Exhaust gas sample in unsaturated wet gas condition is induced and cooled in a cooler 7 and made in saturated wet gas condition and temp. T and flow rate F of the exhaust gas sample before entering into the cooler 7 and temp. T and flow rate F of the exhaust gas sample after leaving the cooler 7 and also water vapor quantity Vw of the exhausted gas sample in saturated wet gas condition are detected respectively and water concentration in the exhaust gas sample is calculated by the detected values thereof. As a detecting part A is composed of connection of the cooler 7, a heater 9, and flow meters 6, 12 in series and temp. and flow rate of the exhaust gas sample sucked in and flowed by a pump 12, measuring error of change in dust and components contained in exhaust gas is small, and simple, exact, and stable detection of water concentration is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for detecting moisture concentration in exhaust gas discharged from an incinerator in a city, etc., and an improvement of the device.

(Prior Art) Urban wastewater supplied to a garbage incinerator contains a large amount of moisture, and the exhaust gas discharged from the incinerator contains a large amount of moisture. The moisture concentration in the waste gas is closely related to the combustion efficiency of the waste, air pollution, and the formation of white smoke from the exhaust gas.In order to achieve automatic control of waste combustion and prevention of air pollution, it is necessary to reduce the moisture concentration in the waste gas. It is essential to be able to detect accurately, easily, and continuously.

Therefore, in conventional waste incinerators, the so-called bridge method and capacitance measuring method are often used to continuously measure the water concentration in exhaust gas. That is, the former converts the difference in thermal conductivity between dry exhaust gas and exhaust gas containing water vapor into a temperature difference between hot wires, and detects the temperature difference between the hot wires using a resistance bridge circuit, thereby determining the moisture concentration in the exhaust gas. It is something to detect.

The latter method takes advantage of the fact that the capacitance value of the capacitance with the adsorbent as a dielectric changes depending on the amount of moisture in the exhaust gas, and measures the capacitance using a capacitance bridge circuit. It detects the moisture concentration inside.

Each of the water concentration measuring methods described above exhibits excellent effectiveness when the components in the exhaust gas to be measured are constant and relatively clean. However, when the exhaust gas from a garbage incinerator is high temperature, high humidity, has a high content of dust and corrosive gases, and the components in the exhaust gas change greatly from moment to moment, it is difficult to accurately determine the moisture concentration. Continuous measurements are difficult, resulting in inaccurate measured values, and correction of the measuring device takes too much effort.

In addition, because a large amount of corrosive gas is contained in the exhaust gas, the hot wire in the resistance bridge circuit and the capacitor electrode in the capacitance bridge circuit are easily corroded, leading to a rise in repair costs. There is.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned problems in measuring the water concentration of exhaust gas from conventional municipal waste incinerators, namely: (1) the inability to accurately and continuously measure water concentration on-site; ■It solves problems such as the time-consuming correction of the measuring device during measurement and the severe damage to the measuring device, which increases repair costs, making it easy and accurate to measure the moisture concentration in exhaust gas from waste incinerators. The present invention provides a method and apparatus for detecting water concentration that enables continuous and stable detection.

(Means for Solving the Problems) The first invention of the present application leads sample exhaust gas in an unsaturated humid gas state to a cooler 7 to cool it, removes a part of water vapor in the sample exhaust gas, and converts it into saturated humid gas. The temperature Tl and flow rate fiFt of the sample exhaust gas before it is brought into a gas state and introduced into the cooler 7, and the temperature T2 and flow rate F of the sample exhaust gas after passing through the cooler 7.
2 and the amount of water vapor Vw2 in the sample exhaust gas in the saturated humid gas state, respectively, and the respective detected values Tt, F+
, T2, F2, and VW2 to calculate the amount of water in the sample exhaust gas.

Further, the second invention of the present application includes a cooler 7 that cools sample exhaust gas in an unsaturated wet gas state to bring it into a saturated wet gas state, and a temperature provided on the inlet side of the cooler 7.

a detector (3) including a temperature gauge 5 and a flow meter 6, a thermometer 10 and a flow meter 11 provided on the outlet side of the cooler 7, and a drain trap 13 for discharging condensed water in the cooler 7; Temperature signal T+ from meter 5 and flow rate signal F1 from flow meter 6
A calculation unit 14 converts the sample exhaust gas flow rate flowing into the cooler 7 into a flow rate at normal temperature and pressure, and a temperature signal T3 from the thermometer IO and a flow rate signal F2 from the flowmeter 11. It includes a calculator 15 that converts the flow rate of the sample exhaust gas flowing out into a flow rate at room temperature and normal pressure, and a function generator 17 that determines the amount of water vapor VW2 in the sample exhaust gas flowing out from the cooler 7 in a saturated wet gas state. The water concentration calculator B is the basic configuration of the invention.

(Function) A part of the exhaust gas from the waste incinerator that contains a large amount of moisture in the form of water vapor, that is, a sample exhaust gas in the state of unsaturated wet gas, is introduced into the cooler, and the gas state at the outlet of the cooler is Cool sufficiently so that the temperature is 100% or higher.

The sample exhaust gas flowing out from the cooler becomes a saturated humid gas state, and the sample exhaust gas undergoes a volume change due to temperature and a volume change corresponding to condensed water.

On the other hand, the amount of moisture in the sample exhaust gas on the cooler inlet side is determined by the amount of water vapor in the sample exhaust gas in a saturated humid gas state on the cooler outlet side, and the amount of water vapor between the cooler inlet and outlet converted to room temperature and normal pressure. There is a certain relationship between the amount of gas and the amount of change in volume, as will be described later. Therefore, the temperature and flow rate of the sample exhaust gas at the inlet and outlet of the cooler are detected, and from each detected value, the volumetric change in gas amount between the inlet and outlet of the cooler is calculated based on the detected values. By calculating the amount of water vapor in the sample exhaust gas in a saturated humid gas state on the cooler outlet side using the psychrometric diagram and gas constant, it is possible to know the amount of water in the sample exhaust gas.

(Example) Fig. 1 is a system diagram of the detection part (4) of the moisture concentration detection device according to an example of the present invention. Suction probe, 3 is sampling probe box, 4 is heating conduit, 5 is cooler inlet thermometer (TI), 6 is cooler inlet flow meter (F1), 7
is a cooler, 8 is a cooler outlet thermometer (T2), 9 is a heater, and 1o is a heater outlet thermometer (T3).

11 is a heater outlet flow meter (F2), 12 is a sample pump,
13 is a drain trap.

The exhaust gas generated from the garbage incinerator is sucked as sample exhaust gas from the flue duct 1 through the probe 2, and is led out through the sampling probe box 3 and heating conduit 4 without condensation, and the temperature (T1) is measured with the thermometer 5. death,
Further, after measuring the flow fi (F1) with the flowmeter 6, it is put into the cooler 7.

In the cooler 7, the sample exhaust gas is sufficiently cooled, and the condensed water 14 is discharged via the drain trap 13. After the condensed water has been discharged and the gas has become a saturated moist gas, its temperature (T2) is measured by a thermometer 8 after leaving the cooler 7 and enters the heater 9.

The sample exhaust gas heated by the heater 9 measures the temperature (T3) with a thermometer 1O, and further detects the flow rate (F2) with a flowmeter 11, and then passes through the sample pump 12 and is discharged to the outside of the system. . The sample exhaust gas is sucked by the sample pump 12.

Next, each detection value T+, T2 . detected by the detection unit A shown in FIG. The processing of Ts, Fl, F2, etc.; that is, the principle of water concentration detection according to the present invention will be explained.

First, the dry gas and water vapor in the combustion exhaust gas can be approximately treated as ideal gases, and the state equation of the ideal gas is expressed by the following equation 0.

P@V=G@R-T-...■ Here, P: Pressure (Kyf/m'), T: Temperature (K
), G: weight (Kgf), ■=volume (→, R: gas constant (KffA9f −K)).

In FIG. 1, assuming that the pressures at the inlet and outlet of the cooler 7 are approximately equal to atmospheric pressure, the sample exhaust gas flow rate Ft (m') at the inlet of the gas cooler 7, that is, the unsaturated wet gas flow rate FI is expressed by the following equation 0.

Here, TI: Sample exhaust gas temperature at the cooler inlet ■,
Vd = amount of dry gas in unsaturated wet gas (fr/), Vw
+: Amount of water vapor in unsaturated wet gas (-.

On the other hand, the sufficiently cooled sample exhaust gas flow ffi F2 (m') in a saturated wet state after passing through the gas cooler 7 is as follows:
It is expressed by the following 0 formula.

Here, Vd: amount of dry gas in saturated wet gas (rrI'
), Vwz: Water vapor amount in saturated humid gas (→, T3:
This is the sample exhaust gas temperature (A) at the outlet of the heater 9.

When the amount of water vapor in the unsaturated wet gas (the amount of water vapor in the sample exhaust gas at the inlet of the cooler) Vw+ is determined from the above equations 0 and 0, the following equation 0 is obtained.

By the way, VW2 (amount of water vapor in saturated humid gas) in the above equation 0 is calculated using an psychrometric chart to find the absolute humidity which is a function of the outlet gas temperature T2 of the cooler 7, and using a gas constant. The volume can be determined by doing this.

Therefore, the amount of water vapor Vw+ in the sample exhaust gas can be determined by knowing the inlet gas temperature TI and inlet gas flow rate F1 of the cooler 7, and the outlet gas temperature T3 and outlet gas flow rate F2 of the heater 9.
It can be obtained by calculating the above equation 0.

Moreover, when the above-mentioned Vw+ is determined, the water concentration W in the sample exhaust gas
(vol/vol1%) can be determined by the following formula 0.

Vw+ +Vd 273
Ft, that is, gas inlet temperature Tl of cooler 7, gas flow rate F1
By detecting the gas outlet temperature T2, the gas outlet temperature T3 of the heater 9, and the gas flow rate F2, the moisture concentration W in the sample exhaust gas can be determined by calculation. 7 and the heater 9, etc., but it is of course better to correct the pressure difference. 0 Figure 2 shows the pressure difference detected by the detection unit in Figure 1 above. It is a block diagram of a computing unit (B) that computes the moisture concentration in exhaust gas using each detection end. In the figure, 14 and 15 are arithmetic units, 16 is a subtracter, 17 is a function generator, 18 is an adder, 19 is an arithmetic unit, and 20 is a water concentration display.

The computing unit 14 is a computing unit that converts the amount of unsaturated wet sample exhaust gas introduced into the cooler 7 into the amount of gas at normal temperature and pressure. The gas temperature signal Ts from the flowmeter 6 and the gas flow rate signal F from the flowmeter 6
+ is input, respectively, and the amount corresponding to the first term of the 0 formula is calculated. Similarly, the computing unit 15 is a computing unit that converts the amount of sample exhaust gas in a saturated humid state from the heater 9 into the amount of gas at room temperature and normal pressure. The temperature signal T3 and the gas flow rate signal F2 from the flow meter 11 are input, respectively, and a quantity corresponding to the second term of the above equation 0 is calculated.

Each signal H1 calculated by the calculator 14 and the calculator 15
, Hz are input to the subtracter 16, and the subtracted signal H3 calculated by the subtracter 16 is input to the adder 18.

On the other hand, the temperature signal T2 from the thermometer 8 installed at the outlet of the cooler 7 is inputted to the function generator 17, and the absolute temperature of the saturated humid gas is determined based on the psychrometric diagram, and the absolute temperature of the saturated humid gas is determined using the gas constant. By calculating, the amount of water vapor vw2 in the saturated humid gas is calculated. Further, a signal H4 representing the amount of water vapor vw2 in the saturated humid gas generated by the function generator 17 is input to the adder 18, where it is added to the signal H3 from the subtracter 16.

The output signal from the adder 18, that is, the signal H6 corresponding to the amount of water vapor Vws in the sample exhaust gas at the inlet of the cooler 7 expressed by the above equation 0 is input to the calculator 19; The flow rate signal F+ from the flow meter 6 provided at the inlet of the cooler and the temperature signal T1 from the thermometer 5 are respectively input, and using these, the water concentration W in the sample exhaust gas expressed by the above equation 0 is calculated. (vo1%) is calculated, and its value is displayed on the moisture display 2o.

Note that in the arithmetic unit B shown in FIG. 2, the subtracter 16 first obtains HIHz, and the adder 18 adds the signal H4 from the function generator 17 to it.
The subtracter 16 may be omitted and the three signals H1, H2, and Hs may be input directly to the adder 18.

Moreover, it goes without saying that each of the above-mentioned detections and calculations are performed continuously.

Furthermore, in this embodiment, a heater 9 is provided after the cooler 7 to dry the sample exhaust gas in a saturated humid gas state, and the outlet gas temperature T3 of the heater 9 is input to the calculator 15. However, the heater 9 may be omitted and the outlet gas temperature T2 of the cooler 7 may be input to the calculator 15 (in this case, T3 in the above equations 0 and 0 is replaced with T2). Of course, this is true.

(Effects of the Invention) As described above, the present invention has an extremely simple configuration of the detection unit A, which only connects the cooler 7, the heater 9, and the flowmeters 6 and 12 in series. Because it is only necessary to suck in gas, circulate it, and detect its temperature and flow rate, even if there is some dust in the exhaust gas or the components contained in the exhaust gas fluctuate, it is not possible to detect moisture using the conventional bridge method. Unlike concentration measurement methods, measurement errors do not increase, and water concentration can be detected easily, accurately, and stably.

In addition, even if the components of detection part A are corroded by corrosive gas in the exhaust gas, they can be replaced extremely easily, and the corrosion of the components will not have a direct adverse effect on the measurement as in the bridge method. In addition, the concentration regulations of hazardous substances based on the Air Pollution Control Act are as follows:
Since it is regulated based on the concentration relative to dry gas, the moisture concentration in the exhaust gas is required to calculate the total amount of emissions from the measured values of hazardous substances. In addition, the exhaust gas discharged from a garbage incinerator equipped with a wet cleaning device tends to generate white smoke due to its moisture concentration, and in order to prevent this, the moisture concentration in the exhaust gas must be adjusted. The present invention has excellent practical effects in preventing air pollution and white smoke as described above.

[Brief explanation of drawings]

FIG. 1 is a system diagram of a detection section A of a water concentration detection device according to an embodiment of the present invention. FIG. 2 is a block diagram of the calculation section B of the water concentration detection device according to an embodiment of the present invention. l Flue duct 2 Probe 3 Sampling probe box 4 Heating conduit 5.8.10 Thermometer 6.11 Flow meter 7 Cooler 9 Heater 12 Sample pump 13 Drain trap 14, 15.19 Arithmetic unit 16 Subtractor 17 Function generation Unit 18 Adder 20 Moisture concentration display T+, T2, T- temperature Fl, F2 flow rate Vwz Moisture content Vwr in sample exhaust gas at cooler outlet
Moisture content A in the sample exhaust gas at the cooler inlet Detector B Moisture concentration calculator

Claims (3)

[Claims] (1) Cooler (7) for sample exhaust gas in unsaturated wet gas state
The temperature (T_1) and flow rate (
F_1) and cooler (7), the temperature (T_2) and flow rate (F_2) of the sample exhaust gas as well as the amount of water vapor (Vw_2) in the sample exhaust gas in the saturated wet gas state are detected, and each of the detected values is (T_1), (T_2), (F_1)
, (F_2), and (Vw_2) to calculate the amount of water in the sample exhaust gas. (2) In the method for detecting moisture concentration in exhaust gas in a waste incinerator as set forth in claim 1, the amount of water vapor (Vw_2) in a sample exhaust gas in a saturated wet gas state is determined using an psychrometric diagram and a gas constant. In addition, the temperature (T_1)
and flow rate (F_1) and temperature (T_2) and flow rate (F_2)
From each detected value, the flow rates (F_1) and (F_2) in the unsaturated wet gas state and the saturated wet gas state are converted to flow values (F) and (F_2) in the normal temperature and normal pressure state, and the water vapor amount (V
w_2) and the amount of change in each of the flow values (F) (F_2) to calculate the amount of water in the sample exhaust gas. (3) A cooler (7) that cools the sample exhaust gas in an unsaturated wet gas state to bring it into a saturated wet gas state;
) a thermometer (5) and a flowmeter (6) provided on the inlet side of the
A detector (A) including a thermometer (8) and a flow meter (11) provided on the outlet side of the cooler (7), and a drain trap (13) for discharging condensed water in the cooler (7); ;thermometer(
A computing unit (
14), the temperature signal (T_3) from the thermometer (10), and the flow rate signal (F_2) from the flow meter (11), the flow rate of the sample exhaust gas flowing out from the cooler (7) is adjusted to the flow rate at room temperature and normal pressure. A calculator for conversion (15) and the cooler (7)
A device for detecting moisture concentration in exhaust gas in a waste incinerator, comprising a function generator (17) that determines the amount of water vapor (Vw_2) in saturated wet gas flowing out from the waste incinerator, and a moisture concentration calculator (B) including a moisture concentration calculator (B).