JPH02298316A - Operation of filter dust collection type exhaust gas treating device - Google Patents

Abstract

PURPOSE:To regulate the removing effect of heavy metal, dioxine and acidic gas by controlling the temp. of exhaust gas to be treated and also controlling the loadings of a deoxidizer to this exhaust gas. CONSTITUTION:In the case of treating the combustion exhaust gas in a filter dust collection type exhaust gas treating device, the temp. of gas to be treated is detected by a temp. detector 4. The feed rate of water is controlled by this signal and the temp. of gas is controlled at the required temp. while the gas is passed through a desuperheater 1. Thereby the removing effect of heavy metal and dioxine can be regulated. Further the feed pipe 6 of a deoxidizer is arranged to the downstream side of the desuperheater 1. Ca(OH)2, etc., are added as the deoxidizer to the exhaust gas therethrough and the removing effect of acidic gas is regulated. Further the filter cloth can be avoided from being clogged by sticking of CaCl2 contained in the dust collecting gas on the filter cloth.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention uses a filtration and dust collection type exhaust gas treatment device to remove harmful substances such as heavy metals and dioxins, as well as hydrogen chloride gas and sulfur oxides. The present invention relates to a method for treating combustion exhaust gas containing acidic gases, and more particularly to a new operating method for adjusting the removal effect of these contained substances and preventing clogging of a filter cloth.

[Prior art and its problems] When the above-mentioned combustion exhaust gas is treated using a filtration and dust collection type exhaust gas treatment device, such as a bag filter, removal of heavy metals and dioxins from the exhaust gas is achieved as a result. In addition, temperature control of the exhaust gas was carried out exclusively for the purpose of safe operation of the equipment and removal of acid gas from the exhaust gas.

However, the removal methods for heavy metals and dioxins and acidic gases such as hydrogen chloride gas and sulfur oxides are completely different, and the removal effect of the former greatly depends on the temperature of the exhaust gas, as shown in Figure 4. On the other hand, the latter removal effect is
As shown in the figure, it is directly influenced by the amount of acid adsorbent added.

By the way, in order to treat exhaust gas containing HC/gas using a filtration and dust collection type exhaust gas treatment device as described above, slaked lime Ca (OH
)z is added. However, HC/ and Ca (OH)
CaCl2 produced by the reaction in step 2 exhibits remarkable deliquescent properties, especially at low temperatures, so there is a problem that CaCl2 adheres to the filter cloth and causes clogging of the filter cloth at low temperatures such as when the operation is stopped or during preparation for operation. there were.

In view of the above-mentioned circumstances, this invention efficiently adjusts the removal effect of harmful substances such as heavy metals and dioxins in exhaust gas, as well as acid gases such as hydrogen chloride gas and sulfur oxides, as well as dust collection. To provide a method that prevents deliquescent CaC/2 from adhering to a filter cloth and causing clogging by suppressing the content of CaCl2 in dust, thereby allowing an exhaust gas treatment device to operate without any trouble. The purpose is to

[Means for Solving Problems] The first method of operating the filtration and dust collection type υF gas treatment device according to the present invention is that when treating combustion exhaust gas using the filtration and collection type exhaust gas treatment device, the exhaust gas to be treated is The method is characterized in that the effect of removing heavy metals and dioxins is adjusted by adjusting the temperature, and the effect of removing acid gases is adjusted by adjusting the amount of deoxidizing agent added to the exhaust gas.

In addition, in the second method of operating the filtering and dust collection type exhaust gas treatment device according to the present invention, the exhaust gas to be treated contains Ca (OH
) 2 is added to remove HC/gas in the exhaust gas as CaCl2 using a filtration/dust collection type exhaust gas treatment device, the content of CaC/2 in the collected dust is detected and CaC/2 is removed.
By adjusting the amount of Ca(OH)2 added according to the content of L2, or by increasing the amount of Ca(OH)2 added at the time of burial and increasing the interval at which the adhering dust is brushed off. It is characterized by suppressing the content of CaCl2 in the dust to a low level.

In the first invention, the deoxidizing agent is slaked lime Ca (O
H)2 is common, but is not necessarily limited to this.

Temperature regulation of the exhaust gas to be treated is usually carried out by washing the exhaust gas with water in a cooling tower.

Adjustment of the amount of water supplied to the cooling tower and the amount of deoxidizing agent added to the exhaust gas are usually performed based on the temperature of the treated gas and the amount of HCl.
This is done by detecting the respective concentrations and controlling the opening and closing of the water supply valve and the deoxidizer supply valve based on the obtained detection signals.

In the second invention, the content of CaCl2 in the collected dust is detected by sampling a part of the collected dust, dissolving it in water, and measuring the degree of Ca in the solution. The amount of Ca(OH)2 added to the exhaust gas and the interval for brushing off the attached dust are adjusted by controlling the opening/closing of the Ca(OH)2 supply valve and the timer for brushing off the dust based on this detection signal. be exposed.

Furthermore, since the HC/a degree in the exhaust gas increases when the fire is buried, the amount of Ca(OH)2 added is increased at the same time as the fire is buried, and the intervals at which the adhering dust is brushed off are increased. the result,
The content of deliquescent CaCl2 in the collected dust is suppressed to a low level, and CaCl is prevented from adhering to the filter cloth and causing clogging.

[Example] Next, the present invention will be specifically explained with reference to the illustrated example.

Example 1 In the attached FIG. 1, combustion exhaust gas containing heavy metals, dioxins, and acid gases such as hydrogen chloride gas and sulfur oxides is first passed through a cooling tower (1). Opening group (1)
A water supply pipe (3) having a valve (2) is arranged at the top of the pipe, and water is injected from the pipe (3). The opening and closing of the valve (2) is regulated by a detection signal obtained by detecting the temperature of the processing gas with a temperature sensor (4), which will be described later.

In this way, by controlling the amount of water supplied, the exhaust gas is adjusted to the required temperature while passing through the cooling tower (1).

A deoxidizing agent supply pipe (6) having a valve (5) is arranged on the downstream side of the cooling tower (1), and Ca (OH)2 is added to the exhaust gas as a deoxidizing agent through the intermediate pipe (6). has been done. Ca
The amount of (OH) added can also be adjusted by adjusting the amount of H
This is done by detecting the carbon concentration with the HC detector (7) and controlling the opening and closing of the valve (5) based on the detected signal.In this way, the required amount of Ca is injected into the exhaust gas.
By adding (OH)2, HC/
The gas is made into CaCl, and other acid gases are made into Ca salt.

The temperature-adjusted exhaust gas to which Ca(OH)z has been added is then passed through a bag filter (8) for dust collection. The temperature and HC/concentration of this process gas are detected by the respective detectors (4) and (7) as described above, and the opening and closing of the valve (2) and the valve (5) are controlled based on the obtained detection signals.

In this way, by adjusting the temperature of the exhaust gas to be treated by washing with water in the cooling tower (1), the removal effect of heavy metals and dioxins by the bag filter (8) is adjusted, and at the same time, the removal of Ca (OH) 2 from the exhaust gas is adjusted. By adjusting the amount added, the effect of removing acidic gases such as hydrogen chloride gas and sulfur oxides in exhaust gas can be adjusted.

Example 2 In the attached FIG. 2, a deoxidizer supply pipe (1a) having a valve (15) is arranged on the upstream side of the bag filter (18), and a deoxidizer is supplied to the exhaust gas through an intermediate pipe (16). As Ca
(OH)2 is added. By thus adding the required amount of Ca(OH)2 to the exhaust gas, the HC/gas in the exhaust gas is converted to CaCl2.

The exhaust gas to which Ca(OH)z has been added is then passed through a bag filter (18) for dust collection.

The bag filter (18) is provided with a device for removing attached dust. The device uses means such as reverse airflow, shaking, and sound waves to remove dust from the filter cloth. This dusting device is equipped with a timer (10),
The device is activated intermittently by a timer (IO).

Part of the dust collected by the bag filter (18) is sampled and dissolved in water, and the content of CaCl2 in the collected dust is determined by measuring the degree of Caa in the solution with the detector (9). Detected. This detection signal controls the opening and closing of the Ca(OH)2 supply valve (15). In this way, the amount of Ca(01()2) added is adjusted according to the content of CaCl2 in the collected dust.As a result, the content of deliquescent CaCl2 in the collected dust is suppressed to a low level, and CaCl2 is filtered out. This prevents it from adhering to the cloth and causing clogging.

Further, the timer (lO) of the brushing device is also controlled by this detection signal.

Example 3 In the configuration shown in FIG. 2, when the fire is buried, υ1. HC in gas
/6 degrees, so Ca(OH) is removed at the same time as the buried fire operation.
The amount of addition of No. 2 is increased, and the intervals at which the adhering dust is brushed off are made closer.

The amount of Ca(OH)z added and the interval at which adhering dust is brushed off are adjusted by changing the respective set values of the valve (15) and timer (10).

As a result, the content of deliquescent Ca C/2 in the collected dust is suppressed to a low level, and CaCl2 is prevented from adhering to the filter cloth and causing clogging.

The other configurations are the same as those of the second embodiment.

[Effects of the Invention] Since the operating method of the filtration and dust collection type exhaust gas treatment device according to the present invention is configured as described above, heavy metals and dioxins in the exhaust gas, as well as acid gases such as hydrogen chloride gas and sulfur oxide, can be removed. By controlling the content of CaCl2 in the collected dust to a low level, it is possible to effectively prevent deliquescent Caf,j2 from adhering to the filter cloth and causing clogging. Therefore, the exhaust gas treatment device can be operated without any trouble.

[Brief explanation of drawings]

Figures 1 and 2 are flow sheets showing examples of the present invention, Figure 3 is a graph showing the relationship between slaked lime supply amount and acid concentration, and Figure 4 is a graph showing the relationship between temperature and dioxin concentration. This is a graph showing. Patent applicant: Hitachi Zosen Corporation L;,:! −・
1.・3h Sekijin Sorei Figure 3 Figure 4

Claims (2)

[Claims] (1) When treating combustion exhaust gas using a filtration and dust collection type exhaust gas treatment device, by adjusting the temperature of the exhaust gas to be treated, the removal effect of heavy metals and dioxins can be adjusted, and the deoxidizing agent applied to the exhaust gas can be adjusted. A method for operating a filtration and dust collection type exhaust gas treatment device, characterized in that the acid gas removal effect is adjusted by adjusting the amount added. (2) When adding Ca(OH)_2 to the exhaust gas to be treated and removing HCl gas in the exhaust gas as CaCl_2 using a filtration and dust collection type exhaust gas treatment device, C in the collected dust is removed.
By detecting the content of aCl_2 and adjusting the amount of Ca(OH)_2 added according to the content of CaCl_2, or by increasing the amount of Ca(OH)_2 added at the time of burial and adjusting the interval for brushing off attached dust. A method for operating a filtration and dust collection type exhaust gas treatment device, characterized in that the content of CaCl_2 in collected dust is suppressed to a low level by making the dust dense.