JPS6223423A - Method for controlling wet type waste gas desulfurization apparatus - Google Patents

Abstract

PURPOSE:To reduce the operation cost of a pump, by measuring the flow amount and SOx concn. of flue gas introduced from an inlet flue and operating a necessary number of spray stages corresponding to the SOx amount operated from the measured values. CONSTITUTION:The measuring signals of the flow amount detector 10 and inlet SOx densitometer 11 provided to an inlet flue 2 are sent to an operational controller 12 to operate the amount of SOx to be absorbed and the optimum number of absorbing spray stages 7 to be operated are calculated in addition to the desulfurization capacity in the cooling spray stage 8 and the cut-off valve 3 of recirculation lines 6 are operated so as to coincide with the calculated number of stages while unnecessary cut-off valves 13 are closed and a necessary number of recirculation pumps 5 are driven and unnecessary recirculation pumps 5 are stopped. The measuring signal from the outlet SOx densitometer 14 of an outlet flue 3 is sent to an operational controller 12 and the number of the recirculation pumps 5 to be operated and the number of the absorbing spray stages 7 are subjected to feedback control.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method of controlling a wet flue gas desulfurization device.

[Prior Art] In boiler equipment, as shown in Fig. 2, a denitrification device, an air heater C, an electrostatic precipitator d, and an absorption tower e are installed in sequence on the downstream side of a boiler a, and denitrate, remove dust, and desulfurize the combustion exhaust gas. After it becomes pollution-free, it is discharged from the chimney f.

As shown in FIG. 3, the absorption tower e has a cylindrical shape and has spray stages 9 arranged in multiple stages at required intervals in the upper part of the tower, and a slurry-like absorption liquid j containing lime etc. is pumped by a pump k. They are circulated and ejected from the spray nozzle h. As shown in FIG. 4, each spray stage g is constructed by combining a required number of spray joint pipes 1 each having spray nozzles h arranged at required intervals.

[Problems to be solved by the invention] ゛However, in the past, the boiler load, that is, the absorption tower inlet SOz
Since the pump k is operated and the absorbing liquid j is spouted from the spray nozzles h of all stages, the operating cost of the pump may be wasted, which is a problem in terms of energy saving. It had become.

Means for Solving Problem E] In order to solve the above-mentioned conventional problems, in the present invention, the desulfurization performance in the absorption tower is determined by the ratio of absorption liquid to exhaust gas (
L/G), and by circulating and supplying the absorption liquid to each spray stage arranged multiple times in the absorption tower through a circulation line equipped with a circulation pump, the inlet flue of the absorption tower is In the method of desulfurizing exhaust gas introduced from
The flow rate of the exhaust gas introduced from the inlet flue and the WJ degree of sulfur oxide in the exhaust gas were measured, and the necessary number of spray stages were operated according to the sulfur oxide amount calculated from the measured values. .

[Function] Since the minimum number of spray stages necessary to absorb 802 in the exhaust gas introduced into the absorption tower is operated, it is possible to stop driving unnecessary circulation pumps, reducing operating costs. can do.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

Figure 1 shows an example of a wet flue gas desulfurization system used in the actual flow of the present invention, in which 1 is an absorption tower, 2 is an inlet flue, 3 is an outlet flue, 4 is an absorption liquid, 5 is a circulation pump, 6 is a circulation line, 7 is an absorption spray stage, 8 is a cooling spray stage,
9 is an eliminator, and the inlet flue 2 is provided with a flow rate detector 10 for measuring the flow rate of exhaust gas and an inlet SO2 concentration meter 11 for measuring 3029 degrees in the exhaust gas, and the flow rate detector 10 and the inlet SO2 concentration are A total of 11 measurement signals are respectively sent to the calculation controller 12, and the calculation controller 12 calculates the absolute amount of population SO2, calculates the number of 7 absorption spray stages required to absorb the 802 m, and The Rfi controller 12 is installed in each circulation line 6 to open the necessary number of cutoff valves 13 and to open unnecessary cutoff valves 13.
to send a signal to each of the shutoff valves 13, and
A drive or stop signal is sent from the calculation fil+controller 12 to each circulation pump 5.

In addition, an outlet SO2 concentration meter 14 is installed at the outlet flue 3 of the absorption tower 1.
is provided, and the S1 measurement signal is sent to the arithmetic controller 12 to feedback-control the number of operating circulation pumps 5 and absorption spray stages 7.

Furthermore, an emergency cooling water line 17 is connected to the downstream side of the circulation pump 16 of the circulation line 15 that circulates the absorption liquid 4 to the cooling spray stage 8, and a flow rate detector (or pressure detector) is provided in the circulation line 15. 18, the circulation line 1
When the flow rate (or pressure) of the absorbing liquid 5 drops below a predetermined value, this signal causes a shutoff valve 19 provided in the emergency cooling water line 17 to be opened. Note that the measurement signal of the flow rate detector (or pressure detector) 18 is also sent to the arithmetic controller 12.

With the above configuration, the exhaust gas that enters the absorption tower 1 from the inlet flue 2 is first transferred to the absorption liquid 4 spouted from the cooling spray stage 8 (in the case of a decrease in the absorption liquid outflow, the exhaust gas is discharged from the emergency cooling water line 17). After being cooled by cooling water), it is desulphurized by the absorption liquid from the absorption spray stage 7 arranged above it and discharged through the outlet flue 3. In addition, when the absorption liquid 4 is spouted from the cooling spray stage 8, it goes without saying that the exhaust gas is cooled and desulfurized at the cooling spray stage 8 at the same time.

Flow rate detector 10 provided in the inlet flue 2 and inlet SOz
The measurement signal of 'fA degree meter 1] is sent to the arithmetic controller 12, and the arithmetic controller 12 outputs the measured flow rate of exhaust gas and SO
The 5O2ffi that should be absorbed from 1 m of 2 concentration is calculated, and if the measurement signal sent from the flow rate detector (or pressure detector) 18 provided in the circulation line 15 to the calculation controller 12 is greater than a predetermined value, the In the spray stage 8 for cold fjl] The absorption spray stage 7 is suitable for taking into account the desulfurization performance.
The number of operating stages is determined, and each shutoff valve 13 of the circulation line G is closed so as to match the number of stages of the absorption spray stage 7, and each unnecessary shutoff valve 13 is closed, and at the same time, the circulation pump of the circulation line 6 is closed. 5 are driven as many times as necessary, and unnecessary circulation pumps 5 are stopped.

Furthermore, the 5O2a degree in the outlet exhaust gas is detected by the outlet 5O21 degree meter 14 provided in the outlet flue 3, and the detection signal is sent to the arithmetic controller 12, which controls the opening according to the 5O2ffi of the inlet. Because the number of shutoff valves 13 and the number of operating circulation pumps 5 are insufficient, 5O2i1 in the outlet exhaust gas
! If the temperature is higher than the upper limit, the shutoff valve 13 is opened and the number of operations of the circulation pump 5 is increased.
If 028 degrees is lower than the lower limit, feedback control is performed to close the shutoff valve 13 and reduce the number of operations of the circulation pump 5.

On the other hand, the cooling spray stage 8 has a cooling circulation line 15.
The required amount of absorption liquid 4 is constantly supplied through the inlet flue 2.
The temperature of the exhaust gas introduced into the absorption tower 1 is lowered,
Burning of the corrosion-resistant lining layer inside the absorption tower 1 is prevented.

If the flow of the cooling circulation line 15 drops below a certain flow m, the shutoff valve 19 of the emergency cooling water line 17 is opened in response to a signal from the flow rate detector 18 or the pressure detector, and the cooling water is sent to the cooling spray stage 8 to prevent damage to the absorption tower 1 due to temperature rise of the introduced exhaust gas.

Note that the method of controlling a wet flue gas desulfurization apparatus of the present invention is not limited to the above-described embodiments, and the object of the present invention can be achieved even without detecting SOz in the exhaust gas in the outlet flue and performing feedback control. It goes without saying that various changes may be made without departing from the gist of the present invention, such as things that can be done differently, cooling water not having to be supplied from the emergency cooling water line, etc.

[Effects of the Invention] As explained above, the method for controlling a wet flue gas desulfurization apparatus of the present invention exhibits various excellent effects as described below.

(1) Since the required number of absorption spray stages is operated by determining 802 m in the inlet exhaust gas, the absorption liquid necessary for SO2 absorption is circulated in just the right amount and the operating cost of the circulation pump is minimized. Become.

(■) A significant running cost reduction effect can be obtained by simply adding a small amount of equipment.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of a wet flue gas desulfurization device used in the implementation of the present invention, FIG. 2 is an explanatory diagram showing an example of boiler equipment,
FIG. 3 is an explanatory diagram showing an example of a conventional absorption tower, and FIG. 4 is a view taken along the IV-TV direction in FIG. 3. 1 is an absorption tower, 2 is an inlet flue, 3 is an outlet flue, 5 is a circulation pump, 6 is a circulation line, 7 is an absorption spray stage, 8 is a cooling spray stage, 10 is a flow rate detector, 11 is an inlet 302
12 is an arithmetic controller, and 13 is a shutoff valve. Patent application Hitoshi Kawajima Harima Heavy Industries Co., Ltd.

Claims (1)

[Claims] 1) A method for desulfurizing exhaust gas introduced from the inlet flue of the absorption tower by circulating and supplying the absorption liquid to each spray stage arranged in multiple stages in the absorption tower through a circulation line having a circulation pump. Measuring the flow rate of exhaust gas introduced from the inlet flue and the concentration of sulfur oxides in the exhaust gas,
A method for controlling a wet flue gas desulfurization apparatus, comprising operating a required number of spray stages according to the amount of sulfur oxide calculated from the measured value.