JPH01153913A - Exhaust gas flow rate measuring instrument for combustion furnace - Google Patents

Abstract

PURPOSE:To measure an exhaust gas flow rate with high reliability by controlling the flow rate of the atomized water in a gas cooler so that the entrance exhaust gas temperature of the gas cooler is constant, and calculating the heat balance of the gas cooler. CONSTITUTION:The gas cooler 2 which cools the exhaust gas of a combustor 1 by atomization is provided on the downstream side of the combustor 1 and the flow rate of the exhaust gas is measured. At this time, the temperature of the exit of the cooler 2 is measured by a temperature detector 5b, whose measured value is sent to a cooler controller 6, which controls the flow rate of the atomized water so that the exit temperature is constant. Then an arithmetic processor 7 calculates the heat balance of the cooler 2 from the point where the heat input and heat output of the cooler 2 become equal to each other, thereby calculating the exhaust gas flow rate.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a device for measuring the exhaust gas flow rate of a combustion furnace such as an incinerator in a waste incineration plant, and in particular to a device for calculating a heat balance. The present invention relates to an exhaust gas flow measuring device for a combustion furnace that calculates the exhaust gas flow rate without installing a dedicated flow meter.

[Prior art] Conventional exhaust gas flowmeters generally include: (1) an orifice flowmeter that measures the flow rate from the pressure difference before and after an orifice plate inserted into the pipe as a restriction, and (2) a concentric double pipe. There are two known methods: one that uses a pitot tube that is placed parallel to the flow, detects the total pressure at the front and the static pressure at the side, and determines the flow velocity from the differential pressure, and the other that uses a turbine meter.

[Problems to be Solved by the Invention] However, the method using the orifice in (2) causes a large pressure loss at the measurement point, leading to an increase in the capacity of the fan that draws the exhaust gas to the outside.

In the case of (2) using a pitot tube, the pitot tube becomes clogged with soot in the exhaust gas and becomes unusable in a short period of time, so a purge device is required, leading to cost increase and missing measurement time.

③ Turbine meters are prone to corrosion and damage to the measuring part.

In order to install the exhaust gas flow meters of roughly The reality is that it is not possible to secure a direct section.

Therefore, the main object of the present invention is to provide an exhaust gas flow rate measuring device for a combustion furnace that enables highly reliable exhaust gas flow rate measurement without installing these flowmeters.

[Means for Solving the Problems] The exhaust gas flow rate measuring device for a combustion furnace according to the present invention measures the flow rate of the exhaust gas in a system including a gas cooler downstream of the combustion furnace that injects and cools the exhaust gas of the combustion furnace. TIJI'71f inside the gas cooler so that the exhaust gas temperature at the inlet of the gas cooler is constant.
The above-mentioned problems are solved by providing a control means for controlling the flow rate of water, and a calculation means for calculating the flow rate of the exhaust gas by calculating the heat balance in the gas cooler.

[Operation] According to the present invention, the temperature of the artificial exhaust gas in the gas cooler becomes constant by controlling the flow rate of spray water in the gas cooler by the control means. In this case, focusing on the fact that the heat input and heat output of the gas cooler are equal (however, the heat loss in the gas cooler can be ignored), the exhaust gas flow rate can be calculated by calculating the heat balance in the gas cooler using the calculation means. Calculated.

[Embodiments] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a block diagram showing an example of the device configuration of the present invention.

In the figure, combustion exhaust gas from a combustion furnace (for example, a garbage incinerator) 1 is cooled by water spray in a gas cooler 2, and is discharged from a chimney 4 via a dust collector 3.

The outlet temperature ts of the gas cooler 2 is measured by a temperature detector 5b, and the measured value is given to a cooler controller 6 (control means). The cooler controller 6 controls the gas cooler self-sprayed rime ice flow rate W so that the gas cooler outlet temperature ts[t] is constant. Control [g/h].

Here, the heat balance in the gas cooler 2 will be considered.

G: Exhaust gas flow rate [Nm3/hlt6
: Gas cooler artificial exhaust gas temperature ['C] tw: Gas cooler spray ice temperature [1] δ: Gas cooler self-propelled water vapor density [g/Nm3] Igta: Gas cooler artificial exhaust gas enthalpy Igti: Gas cooler exit exhaust gas enthalpy iw: Heat input to the gas cooler 2 as enthalpy of sprayed ice in the gas cooler (1+n is given by the following formula.

1+n=(Gh-Wn/δ), i, to+Wo-i
w・−・・・・ (1) Similarly, the heat output Q out from the gas cooler 2 is calculated by the following formula: % Heat input Qtn and heat output Q of the gas cooler 2. ut is equal to ut assuming that the heat loss of the gas cooler 2 is negligible.

Therefore, from equations (I) and (o), the gas cooler outlet exhaust gas flow rate Gh is given by the following equation.

G hi(i w i 1Ita・δ)・Wn)/
(i, rt-1)... (II+) Moreover, each enthalpy is approximated by the following formula.

11tG=C3+C2・to・・・・・・(!
v) 1w=C3+C4・tw... (V
)11tffi=C5+C6・ts・・・・・・
(v■) (However, C and -C4 are constants.) In these formulas (IV) to (Vl), C4 to C4 can be measured in advance, and C5 and C6 are the gas cooler self-spraying rime ice flow rate W. Although it changes slightly depending on the value of , it can be measured as a function of the gas cooler self-spouting water flow rate Wn.

When these equations Hv) to (Vl) are substituted into equation (II!), the gas cooler outlet exhaust gas flow rate Gh is given by the following equation.

G h = ((:3”C3tw-(C++C2ta)
/ δ・W, )/ (Cs (wn+ +(:6fWn
l ・t5-t) [Nm3/h]... (■
) (However, C3fWnl, C81W.) is a constant 05°Ca expressed as a function of the gas cooler self-spouting water flow "X W n." To explain the calculation of the exhaust gas flow rate Gh with reference to FIG. The inlet exhaust gas temperature tG of No. 2 is measured by the temperature detector 5b, and the measured value is given to the arithmetic processing device 7 (arithmetic means).

Also, the flow rate W of spray water in the gas cooler 2. .

The temperature tw and the vapor density δ are each given to the arithmetic processing unit 7 via the cooler controller 6. Pre-measured constant C7
~C4 and n Function representation of water flow rate Wn C5N1n1,
C611n+ is set and input via a human-powered device 8 attached to the arithmetic processing device 7.

The arithmetic processing unit 7 calculates O8+□ based on the spray water flow rate Wn given via the cooler controller 6.

The value of 061Wnl is calculated, and the exhaust gas flow rate Gh is calculated using the calculation result, each measured value, and the set input values C1 to C4 according to the above-mentioned formula (■).

In the above embodiment, each constant is set and inputted from the input value @8, but it may be stored in the memory of the arithmetic processing unit 7 in advance. Furthermore, although the water 1/2 exposure amount controller 6 and the arithmetic processing unit 7 are shown as constituent elements each having separate functions for the purpose of explanation, they may also be realized by a digital controller that has the same functions as those described above. good.

[Effects of the invention] As explained above, this invention allows the exhaust gas flow rate to be calculated by calculating the heat balance, so there is no need to provide a direct section for measurement or an exhaust gas flowmeter in the exhaust gas duct. Instead of conventional exhaust gas flow! The cost and space required for measurement can be significantly reduced.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of an installation configuration according to an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Combustion furnace, 2... Gas cooler, 3... Collector, 4... Chimney, 5a, 5b... Temperature detector, 6...
...Cooler controller, 7...Arithmetic processing unit, 8...
Human Power Equipment Representative Masaru Sato Patent Attorney Figure 1 6: Cooler controller 8: Input device

Claims (1)

[Claims] In a system that measures the flow rate of the exhaust gas in a system including a gas cooler downstream of the combustion furnace that spray-cools the exhaust gas of the combustion furnace, the temperature of the exhaust gas at the inlet of the gas cooler is constant. A combustion furnace comprising: a control means for controlling the flow rate of spray water in the gas cooler; and a calculation means for calculating the flow rate of the exhaust gas by calculating the heat balance in the gas cooler. Exhaust gas flow rate measuring device.