JP3025129B2 - Operating method of boiler exhaust gas treatment device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method of operating a boiler exhaust gas treatment apparatus installed in order to remove dust and SO _X in the exhaust gas of a coal fired boiler.

[0002]

BACKGROUND OF THE INVENTION FIG 2 is a system flow diagram of an apparatus for removing dust and SO _X in the exhaust gas of a conventional coal fired boiler.

[0003] The gas leaving the boiler 1 is an air preheater (AH).
2. Cooled by the GGH heat recovery unit 3a and removed by the dry electric precipitator 4. Further, SO _X is removed by the desulfurization device 5, heated by the GGH reheater 3b, and sent to the chimney. The dry type electrostatic precipitator 4 is a device for removing dust,
Dust collection efficiency varies depending on gas temperature and coal properties. The heat recovery unit 3a and the reheater 3b recover heat from the exhaust gas before the desulfurization unit 5 via a heat medium and reheat the exhaust gas after the desulfurization unit 5. The heat recovery amount is adjusted by adjusting the flow rate of the heat medium. And the amount of reheating can be adjusted by heating the heat medium with a separate heater.

[0004] In the conventional operation, the outlet gas temperature of the AH2 changes with the fluctuation of the outside air temperature and the fluctuation of the boiler load.
Further, since the outlet gas temperature of the GGH heat recovery unit 3a, that is, the gas temperature at the inlet of the dry-type electrostatic precipitator 4 changes, the dust-collecting efficiency of the dry-type electric precipitator 4 also constantly changes.

[0005]

The dust collection efficiency of the above-mentioned conventional dry type electrostatic precipitator is that the exhaust gas temperature is 80 to 110 ° C.
In the range, the electrical resistivity of fly ash varies depending on the type (brand) of coal, and therefore differs as shown in FIG.
For example, the allowable dust collection efficiency may be lower in a low temperature region such as coal B, or lower than the allowable dust collection efficiency in a high temperature region such as coal C. For this reason, when the outside temperature in winter is low or the boiler load is low,
When the coal B is used when the exhaust gas temperature is low, when the temperature outside the summer is high, or when the boiler load is high, when the coal C is used when the exhaust gas temperature is high, the dust collection efficiency decreases. The emission dust concentration exceeds the allowable value,
The operation of the plant was sometimes restricted.

[0006]

The present invention employs the following means to solve the above-mentioned problems.

That is, as an operation method of the boiler exhaust gas treatment apparatus, in the exhaust gas treatment apparatus in which the exhaust gas of a coal-fired boiler is cooled by an air preheater and a heat recovery device and then removed by a dry electric dust collector, Of dust equipment
Inlet gas temperature and outlet dust concentration are detected, and when the dust concentration is equal to or higher than a predetermined value, the inlet gas temperature is within a predetermined range.
The amount of cooling medium in the heat recovery unit depending on whether it is higher or lower
The increases and decreases the inlet gas temperature of the dry electrostatic precipitator is adjusted the operation of the heat recovery device such that a predetermined range, the outlet dust concentration of the dust collecting apparatus that does not exceed the predetermined value.

[0008]

[Action] by the above method of operation, for example, the exhaust gas temperature Tokoro
During operation in a region lower than the predetermined range, when the dust concentration at the outlet of the dry type electrostatic precipitator is detected and becomes higher than a predetermined value,
The amount of heat recovered by the heat recovery device is reduced, and the dust collection efficiency is improved by increasing the inlet gas temperature of the electrostatic precipitator,
The exit dust concentration does not exceed a predetermined value.

During operation in a region where the temperature of the exhaust gas is higher than a predetermined range, for example, the concentration of dust and dust at the outlet of the dry-type electrostatic precipitator is detected. When the concentration becomes higher than a predetermined value, the amount of heat recovered by the heat recovery device is increased. As the temperature decreases, the dust collection efficiency is improved, and the concentration of the dust in the outlet does not exceed a predetermined value.

[0010] As described above, the operation is performed so that the dust concentration does not always exceed the predetermined value.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment according to the method of the present invention will be described with reference to FIGS.

The parts described in the prior art will be assigned the same reference numerals and their explanation will be omitted, and the parts related to the present invention will be mainly described.

In FIG. 1, the heat carrier lines of the heat recovery unit 3a and the reheating unit 3b are connected so as to circulate sequentially. At this time, a heat medium heater 10 is provided at the inlet of the heat medium line of the reheater 3b. Further, an outlet and an inlet of the heat medium line of the heat recovery device 3a are connected via a bypass valve 9. A thermometer 6 is attached to the inlet of the dry electric precipitator 4, and a soot concentration meter 7 is attached to the outlet thereof, and sends outputs to the temperature controller 8. Further, the output of the temperature control device 8 is supplied to the bypass valve 9.
Sent to

In the above configuration, the dust concentration at the outlet of the dry-type electrostatic precipitator 4 varies depending on operating conditions such as the coal used, the boiler load, and the gas temperature at the entrance of the electric precipitator.
Usually, it is below the allowable value, and is monitored by a dust concentration meter 7 at the outlet of the electrostatic precipitator.

However, when the operating conditions change due to a change in the type of coal, etc., the dust collecting efficiency of the electric dust collecting device decreases, and if the concentration of dust at the outlet of the electric dust collecting device exceeds an allowable value, the dust concentration meter 7 detects this. Then, a feedback signal is sent to the temperature control device 8. The temperature controller inputs a signal of the gas temperature at the inlet of the dry electrostatic precipitator from the thermometer 6 and a signal of the dust concentration at the outlet of the electrostatic precipitator, so that the inlet of the dry electrostatic precipitator does not exceed the allowable value. A valve opening signal for adjusting the gas temperature is calculated and output. The opening of the bypass valve 9 is adjusted by the valve opening signal.

For example, as shown in FIG. 3, when C coal is used and the inlet gas temperature is in the range of 100 to 110 ° C., the opening of the bypass valve 9 is reduced, and when the bypass amount of the heat medium is reduced, the heat is reduced. The amount of collection increases. Therefore, the temperature of the inlet gas is reduced, the dust collection efficiency of the electrostatic precipitator is increased, and the concentration of dust at the outlet of the precipitator does not exceed the allowable value.

Further, for example, when coal B is used and the inlet gas temperature is in the range of 80 to 90 ° C., the opening of the bypass valve 9 is increased, and when the bypass amount of the heat medium increases, the heat recovery amount decreases. . Therefore, the temperature of the inlet gas rises, the dust collection efficiency of the electrostatic precipitator increases, and the dust concentration at the outlet of the precipitator does not exceed the allowable value.

If the amount of heat recovery is less than the required amount in the GGH reheater 3b, the heat medium heater 1
0 operates to compensate.

In this way, the operation is always performed so that the dust concentration at the outlet of the electrostatic precipitator does not exceed the allowable value.

[0020]

As described above, according to the method of the present invention, an increase in the soot and dust concentration due to a difference in the type of charcoal used is suppressed, and the operation is always performed so as not to exceed the allowable value.

[Brief description of the drawings]

FIG. 1 is a system diagram of one embodiment according to the method of the present invention.

FIG. 2 is a configuration flowchart of a conventional device.

FIG. 3 is an operation explanatory view of the embodiment and the conventional device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 boiler 2 air preheater 3 a heat recovery unit 3 b reheater 4 dry electric precipitator 5 desulfurizer 6 thermometer 7 soot and dust concentration meter 8 temperature controller 9 bypass valve 10 heating medium heater

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masatoshi Tamai 1-1-1, Wadazakicho, Hyogo-ku, Kobe-shi Inside Mitsubishi Heavy Industries, Ltd.Kobe Shipyard (72) Inventor Katsutoshi Yada 1-chome, Wadasakicho, Hyogo-ku, Kobe-shi No. 1-1 Inside Mitsubishi Heavy Industries, Ltd.Kobe Shipyard (72) Inventor Retsu Sakai 2-5-1 Marunouchi, Chiyoda-ku, Tokyo Inside Mitsubishi Heavy Industries, Ltd. (72) Inventor Tsuneo Higashi 5007 Itozakicho, Mihara City, Hiroshima Prefecture Mitsubishi (56) References JP-A-6-292839 (JP, A) JP-A-6-134341 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F23J 15/08 F23J 15/06

Claims (1)

(57) [Claims] In an exhaust gas treatment apparatus for cooling an exhaust gas from a coal-fired boiler by an air preheater and a heat recovery device, and then removing the exhaust gas by a dry electric dust collector, an inlet gas temperature and an outlet dust of the dry electric dust collector are provided. detecting the concentration, when the dust concentration is equal to or greater than the predetermined value, the inlet gas temperature is predetermined
Coolant for the heat recovery unit above or below the range
Adjust the operation of the heat recovery device so that the inlet gas temperature of the dry type electrostatic precipitator falls within a predetermined range by increasing or decreasing the body weight ,
A method for operating a boiler exhaust gas treatment device, wherein the concentration of dust and dust at the outlet of the dust collection device does not exceed the predetermined value.