JPS604722B2 - Exhaust smoke purification method and device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and device for purifying flue gas, and more specifically, it also removes fine water-soluble salts and other harmful substances in addition to dust contained in flue gas from various combustion devices. It concerns the removal method and device.

Various methods and devices have been proposed for the purpose of purifying flue gas.

Recently, in order to prevent pollution, many combustion exhaust gases are dedusted and desulfurized at the same time, and green treatment is generally adopted for exhaust gas treatment in this case, but after treatment, the exhaust gas contains JI
The ``dust'' measured in the SZ Spotted Female is ``inherent dust (water-insoluble) ``dissolved salts in the entrained mist (
Water-soluble salts such as sodium salts and calcium salts) are contained, and it is difficult to remove them mechanically, especially 'o'', and for this reason, many of them fail to meet the smoke emission regulation values.

When conventional equipment uses seawater, caustic soda, and lime for cleaning exhaust gas, it is difficult to avoid the presence of fine particles of salts in the exhaust gas after cleaning, and this is the biggest drawback of wet gas cleaning equipment. In order to remove the dust, it was necessary to consider the use of a wet electrostatic precipitator.

Furthermore, when using an overflow type electrostatic precipitator, there are operational problems such as corrosion of the device and scale adhesion, which, combined with high equipment costs, makes it unsuitable for waste gas treatment of small to medium capacity in particular. Conventionally,
It has been known that the condensation of moisture in the air has a great effect on dust removal, but the inventor of the present invention has conducted various studies based on the knowledge that ultrafine particles of water-soluble salts are captured in this condensed moisture, and has found that A fan is installed in the flow path of the exhaust gas, a humidifier is installed in front of the 8E fan and a condensed water filtration device is installed behind the 8E fan, and a throttle is installed in front of the humidifier and at least one of the rear of the condensed water separator. By installing this, the saturated water in the exhaust gas is condensed using the pressure difference before and after the fan, and this condensed water is removed downstream of the fan, resulting in a highly effective dust removal effect.

Next, a detailed explanation will be given with reference to drawings showing an example of the implementation of the present invention.

The throttles 1 and 1' are for suppressing the flow of exhaust gas in the flow, and are, for example, orifices, venturi tubes, etc.
Various types of dampers, valves, cocks, etc. can be adopted and used. This throttle needs to be provided at least either in front of the humidifying device 2, which will be described below, or in the rear of the condensed water separation device 4, and in some cases, it can be provided in both. In the present invention, the term "front" and "rear" refer to the upstream side of the exhaust gas flow as the front side, and the downstream side of the exhaust gas flow as the rear side.
The throttles 1 and 1' are provided to generate a high pressure difference between the front and rear sides of the exhaust fan by driving the 9E wind fan 3, and the degree of the throttle is set arbitrarily depending on the purpose of use. The humidifying device 2 is used to give sufficient humidity to the exhaust gas in front of the exhaust shore, preferably to saturate it with water vapor. Various humidifying devices can be used, but steam injection, water mist, etc. are suitable, and an exhaust gas is used. When the diaphragm 1 is installed in front of the exhaust fan, it is preferable to install the diaphragm 1 at the same position as the humidifier or just in front of the humidifier.

The 9E blower 3 is used to transport exhaust gas and create a high pressure difference between the front and rear sides of the blower, and a fan, a blower, or any other type of blower may be used.

The condensed moisture extraction device 4 is installed behind the 9E fan 3, and separates and removes the condensed moisture in the exhaust gas generated by the pressurizing effect of the exhaust fan 3, thereby removing fine dust (water-insoluble) and entrained particles in the exhaust gas. The water-related salts in the mist are removed at the same time, and any commonly used centrifugal or inertial mist removal device can be used.

However, a filter-type mist removal device is not suitable in this case because it causes clogging. Since this device has the above configuration, when the exhaust fan 3 is driven, the exhaust gas 6 flowing from the front is suppressed by the throttle 1 and is forcibly transferred to the rear by the exhaust fan 3. As a result, the space between the aperture 1 and the aE fan 3 is reduced in pressure, and is then saturated with water vapor by the humidifying device 2 provided between the aperture 1 and the aE fan 3.

After the exhaust gas saturated with water vapor is sent out by the exhaust fan 3, it is elevated and returns to the original pressure state, or the original pressure is reduced by the condensed water pipe 4, other throttles 1', and other flow path obstructions. The voltage is further increased. In this way, the exhaust gas that is reduced in pressure and saturated with water vapor in front of the exhaust fan is elevated and becomes supersaturated with water vapor at the rear of the exhaust fan.
Moisture condensation occurs instantly.

When this exhaust gas is subsequently passed through the condensed water separator 4, the generated condensed water is separated from the exhaust gas.

At this time, water-insoluble dust adhering to the condensed water and water-soluble salts dissolved in the condensed water are removed together with the condensed water. The greater the amount of condensed water generated, the better the desired dust removal effect will be, but the greater the pressure difference before and after the SE blower, or the higher the exhaust gas temperature, the greater the amount of condensed water generated.

In the embodiment of the present inventor, in an actual incinerator exhaust gas treatment equipment equipped with a seawater washing tower and a medium-pressure venturi scrubber, medium-pressure venturi scrubbers are adopted as the throttle 1 and the humidifying device 2, and the The pressure difference is 50 mm water column (
The following results were obtained when the exhaust gas temperature was 35 to 40° C., and the amount of dry exhaust gas passing was 20,000 N/day. Table 1 The condensed water broiler device 4 has a special inertial type (Euroform).
A mist eliminator (manufactured by Nippon Insulator) was used to remove condensed water at a high rate.

The properties of the separated condensed water were as follows.
Table 2 The color of condensed water is black because it contains fine particles of unburned carbon.
It also contained dissolved sodium chloride in seawater, and was as salty as seawater.

Each device constituting the flue gas purification device of the present invention can be easily incorporated into existing exhaust gas treatment equipment, and when improving the capacity of an existing dust removal device, for example, the exhaust dust concentration can be reduced to 0.2 at the current level. This has the advantage that it can be implemented without a large capital investment if you want to reduce it from ~0.5 night/N to 0.2 night/N or less.

In many cases, the only equipment required is to replace the exhaust fan, or if a Venturi scrubber is installed and a high-pressure artificial fan is already in use, a condensed water draining device is installed after the 8E fan as shown in the drawing. alone can be effective. Note that an exhaust gas cleaning device that uses seawater, caustic soda, or lime must be placed in front of the exhaust fan 3 to prevent water-soluble salts from being entrained in mist.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the configuration in the case of implementing the present invention. 1, 1'...
Aperture, 2... humidifier, 3... 9E fan, 4. ．． ．． ．．・
・Condensed moisture koji device, 5... Manometer, 6,6'
...Indicates exhaust gas.

Claims (1)

[Claims] 1. A pressure difference generating section is provided in a part of the flow path of the flue gas that has passed through the wet gas cleaning device, and furthermore, a pressure difference generating section is provided at least in front and behind the pressure difference generating section with respect to the flow of the flue gas. A throttle is provided in one flow path so that the front becomes a low pressure part and the back becomes a high pressure part, and by supplying moisture in the low pressure part, water soluble salts and dust in the flue gas are captured to almost saturate with water vapor, A flue gas purification method characterized in that the moisture generated in a supersaturated state of steam in a high-pressure section is then condensed and separated, thereby separating and removing water-soluble salts and dust together with the condensed water. 2. An exhaust fan that can generate a pressure difference in a part of the flow path of the flue gas that has passed through the wet gas cleaning device, a humidifier in front of the exhaust fan for the flow of exhaust smoke, and a centrifugal or centrifugal type humidifier behind the exhaust fan. 1. A flue gas purification device comprising a condensed water separation device using an inertial mist removal method, and further comprising a throttling device before the humidification device and after the condensed water separation device.