JPH0240410A - Automatic combustion control of municipal waste incinerating furnace - Google Patents

Abstract

PURPOSE:To control exactly without delay an incinerating furnace according to a variation in the qualities of refuse by calculating the low calorific value based on the moisture content in the exhaust gas that is produced by the combustion and the concentration of oxygen. CONSTITUTION:An air discharge port 15 in an incinerating furnace 1 communicates with a wet type gas washing device 19 via an electric precipitater 18. At the outlet of a fast cooling and washing section 20 in the wet type gas washing device 19 a first temperature sensor 23 is provided, and at the inlet of a wet type gas washing device 19 an oxygen sensor 25 and second temperature sensor 26 are provided, and they are connected to a calculator 27. In the calculator 27 the amount of the dry gas that is generated during the combustion of dry refuse is calculated from the concentration of oxygen, and from this and the moisture content in the exhaust gas the moisture content in the dusts are calculated, and from the correlation beforehand provided between the moisture content and low calorific value the low calorific value of the refuse that is thrown in is calculated to control the incinerating furnace.

Description

[Detailed description of the invention] Industrial applications The present invention relates to an automatic combustion control method for a municipal waste incinerator.

Conventional technology Conventional automatic combustion control of municipal waste incinerators
The procedure was as shown in the flowchart in the figure. First, various process data (temperature, pressure, flow rate, etc.) for each process of the municipal waste incinerator is collected, heat balance is calculated from this process data, and the set amount of steam generation is calculated. Then, PID calculation is performed from the calculated set steam generation amount and steam generation amount, and the calculated value is used as the burn-out point,
Correct calculations were performed based on the thickness, bulk specific gravity, etc., and the speeds of the bushings and stokers were controlled based on the calculated values, or the opening and closing of the combustion air damper was controlled. In order to perform operations that appropriately respond to changes in waste quality (lower calorific value), it is necessary to accurately understand the lower calorific value, but it is impossible to actually measure the lower calorific value. For this reason, conventionally, low-level V!
As a method for estimating the amount, heat balance calculation was performed as follows.

W': Amount of waste incinerated (t/h) G': Amount of steam generated in the boiler (t/h,
)He: Lower calorific value (estimated amount) of waste (Nical/+q
r) K: Parameter determined from other process data such as combustion air flow rate cr' = KxHe It was impossible to continuously measure the amount of trash incinerated, as the trash was dumped into the incinerator intermittently by a trash crane. To do this, data had to be collected over a period of 1 to 2 hours, making it impossible to grasp the current combustion status in a short period of time, resulting in a time delay in control and poor control accuracy. . For this reason, it is possible to follow sudden changes in the quality of the garbage, resulting in a ``heaped garbage pattern'', in which the quality of garbage suddenly deteriorates and the garbage piles up on the stoker and does not burn. , resulting in a decrease in steam and an increase in burnout loss, or a "garbage cutting pattern", in which the quality of the waste suddenly improves and the amount of waste being burned on the stoker decreases.
There was a problem in that the amount of steam suddenly decreased and the NOx'a degree increased.

The present invention solves the above problems by providing a municipal waste incinerator that can calculate the lower calorific value of waste within a short period of time, eliminate time delays, and accurately deal with fluctuations in waste quality. The aim is to provide an automatic combustion control method.

Means for Solving the Problems In order to solve the above problems, the present invention calculates the moisture and oxygen concentrations in the exhaust gas discharged from the incinerator, and calculates the amount of dry gas generated when dry waste is combusted from this oxygen concentration. The moisture content of the waste put into the incinerator is determined from the relationship between the amount of dry gas and the moisture in the exhaust gas, and from the correlation between the moisture content of the waste and the lower calorific value, which was determined in advance as a statistical model, The structure is such that the lower calorific value corresponding to the moisture content of the garbage is estimated, and the incinerator is operated appropriately based on the estimated lower calorific value.

Effect With the above configuration, the lower calorific value is estimated using the moisture and oxygen concentrations in the exhaust gas generated by combustion as indicators, so the lower calorific value of the garbage currently being combusted can be calculated within a short time. As a result, the incinerator can be properly controlled without any time delay in response to fluctuations in waste quality.6 Embodiments An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, a hopper 3 for charging garbage 2 is formed on one side of an incinerator 1, and a garbage crane 4 is provided above an input port 3a of the hopper 3. A stoker 5 for holding and burning the waste 2 is provided inside the incinerator 1, and the stoker 5 is connected to a dry stoker 5a from the side of the homper 3 according to the combustion stage of the waste 2. and combustion stoker 5b and after-combustion stoker 5C
It is divided into three stages. Also, hopper 3
A button 6 is provided at the bottom of the button 6.
is for pushing the waste 2 onto the drying stoker 5a. A hood 7 is provided below the stoker 5, and the hood 7 is formed to guide primary air into the incinerator 1 through the stoker 5 and to guide ash to the ash bit 8. Further, a forced air blower 9 is provided in communication with the hood 7. And on the other side of the incinerator 1,
An ash discharge port 10 is formed adjacent to the after-combustion stoker 5C, and an observation window 1a for observing the combustion state within the incinerator 1 is formed near the ash discharge port 10. In addition, an industrial television camera (ITV) is installed corresponding to the observation window 1a.
) 11 are arranged. The incinerator 1 is provided with a start burner 12 and an ITV 13 for observing the combustion state of the start burner 12. Further, a secondary air blower 14 is provided in communication with the upper interior of the incinerator 1, and a waste heat boiler 16 is arranged near the exhaust port 15 in the incinerator 1. Then, the waste heat boiler 16 communicates with the turbine power generation unit 117,
Exhaust port 15 is electrical! [Communicated with the wet gas cleaning device 19 via 1g.] And this wet scum cleaning device 1
9 has a quenching cleaning section 20 and a dehumidification section 21, and inside the wet gas cleaning device 19, a first temperature sensor 23 of a temperature detection device 22 is provided at the outlet of the quenching cleaning section 20. It is being In addition, at the entrance of the wet gas cleaning device 19,
An oxygen sensor 25 of the oxygen concentration detection device 24 and a second temperature sensor 26 of the temperature detection device 22 are provided. Both the temperature detection device 22 and the oxygen concentration detection device 24 are connected to a calculation device 27.

The effects of the above configuration will be explained below.

First, the garbage 2 put into the hopper 3 by the garbage crane 4 is pushed onto the drying stoker 5a by the busher 6, and is dried by the heat in the incinerator 1. Then, the dried garbage 2 is pushed by the garbage 2 that is subsequently thrown in, moves onto the combustion stoker 5b, receives air supplied from the forced air blower R9, and burns. Further, the combustible garbage is further combusted while moving to the post-combustion stoker 5c, and ash is discharged from the ash outlet 9 to the ash pinto 8. Then, the combustion gas receives air supplied from the secondary air blower l1114 and is further combusted, and after heat exchange in the waste heat boiler 16, it passes through the electrostatic precipitator 18 and the wet gas cleaning bag r! Sent to 119. Furthermore, the exhaust gas sent to the wet gas cleaning device 19 is
It is cooled in the quenching washing section 20 and sent to the next processing system through the dehumidification section 21. Then, at the entrance of the wet gas cleaning device 19, the oxygen sensor 25 and the second temperature sensor 26 detect the oxygen concentration and temperature in the exhaust gas, and the oxygen concentration is sent as an electrical signal from the oxygen concentration detection device 24 to the calculation device 27. , the temperature is sent from the temperature detection device 22 to the calculation device 27 as an electrical signal.

Further, the first temperature sensor 23 detects the temperature of the exhaust gas at the outlet of the quenching cleaning section 20, and this temperature is sent as an electrical signal from the temperature detection device 22 to the calculation device 27.

Then, in the arithmetic unit 27, the following hand) 1n
Calculations are made according to

First, the exhaust gas temperature at the outlet of the quenching cleaning section 20 of the wet gas cleaning device 19 is the adiabatic saturation temperature of the exhaust gas at the inlet of the wet gas cleaning device 19. Therefore, the exhaust gas temperature at the outlet is Tt ('C), and the exhaust gas molar humidity at the outlet is Hl (moisture hgnol/dry gas kgn
ol), the exhaust gas temperature at the inlet is T2, and the exhaust gas humidity is N2, then a relationship as shown in FIG. 2 exists. In FIG. 2, the molar saturation humidity curve X can be expressed as Ps -10A-7 from Andonie's equation. However, A, B, and C are constants, and Ps is a pressure value. Also, the adiabatic cooling line Y is approximately as follows: H=DT+E ・・・・・・・・・(
2). However, D and E are parameters. Therefore, Hl can be found by substituting the actually measured 1 into equation (1). N2 can then be found by substituting the actually measured T2 into equation (2).

The garbage 2 has a configuration as shown in FIG. However, C: Amount of combustible carbon in the treated material (-) h: Jl Hydrogen amount 0: Nol Oxygen amount S 2 No I Sulfur amount N
: 1 nitrogen Cl 2 salt
It is basic. Here, the composition of the dried garbage 2 is the same, and only the water content W varies. Furthermore, the gas composition when the garbage 2 is burned is as shown below.

Theoretical air amount Low = 8.89C + 26.7fh - 0/8) +3
．． 333-13) If the air ratio is -m, then C02= 1.87x C・・・・・・・・・(4)0
2 = 0.21X (m −1) X Low ---
-... f5) N2 = 0.79X tov
m −−−−・−・−(6) N20=11.2
Xh+1.244 W ・・・・・・・・・(7) Dry gas amount DG=CO2+02 +N2・・・・・・・・・
...(8) Therefore, DG is obtained by substituting the actually measured 024 degrees into equation (9), and the obtained DG and previously obtained H2 (exhaust gas humidity)
Substituting and into equation (10) to find H20, the obtained t■2
W is determined by substituting 0 into equation (7).

In addition, there is a fourth
As shown in the figure, there is a statistically clear correlation. Therefore, the lower calorific value He corresponding to the water W determined previously is estimated from FIG.

Then, the combustion in the incinerator 1 is controlled by operating the bushing 6 and the like based on the obtained lower heat generation iHe.

Effects of the Invention As described above, according to the present invention, the lower calorific value is estimated using the moisture and oxygen concentrations in the exhaust gas generated by combustion as a yardstick.
Calculations can be made within a short period of time, and as a result, the incinerator can be accurately controlled in response to fluctuations in waste quality without any time delay.

[Brief explanation of the drawing]

Fig. 1 is an overall configuration diagram showing one embodiment of the present invention, Fig. 2 is a diagram showing the relationship between exhaust gas temperature and molar humidity, Fig. 3 is a diagram showing the composition of waste components, and Fig. 4 is a diagram showing the composition of waste gases. A statistical model diagram showing the relationship between moisture and lower calorific value, and FIG. 5 is a flowchart diagram showing conventional control. 1...Incinerator, 2...Garbage, 5...Stoker, 6
... Butsusha, 18... collection all! , 19... Wet gas cleaning device, 20... Rapid cooling cleaning section, 22... Temperature detection device, 23... First temperature sensor, 24... Oxygen concentration detection device, 25... Oxygen sensor , 26... Second temperature sensor, 27... Arithmetic device. Agent Yoshihiro Morimoto 2 Figure 3 Figure 4 Figure 'Hfm'F-/7JXW C'10) Figure S αm1 = 1 4 departments

Claims (1)

[Claims] 1. Determine the moisture and oxygen concentrations in the exhaust gas discharged from the incinerator, determine the amount of dry gas generated when dry waste is burned from this oxygen concentration, and calculate the amount of dry gas produced in the incinerator based on the relationship between this amount of dry gas and the moisture in the exhaust gas. The moisture content of the input garbage is determined, and the lower calorific value corresponding to the moisture content of the input garbage is estimated from the correlation between the moisture content of the garbage and the lower calorific value, which has been determined in advance as a statistical model. An automatic combustion control method for a municipal waste incinerator, characterized in that the incinerator is operated appropriately based on the estimated lower calorific value.