JPS5836280B2 - Water treatment method for heat exchanger for sintering exhaust gas treatment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a water treatment method for a heat exchanger in an apparatus for treating exhaust gas from a sintering machine or the like.

The sintering exhaust gas generated from the sintering machine is 1 million Nrn'/
In a large amount of Hr or more, the dust in this exhaust gas is 50 ~
200 m9/Nm'', and furthermore, the exhaust gas contains 10 to 12% moisture.

When discharging (dispersing) such sintering exhaust gas into the atmosphere, it is necessary to make it harmless in order to prevent pollution, etc. Therefore, the exhaust gas is desulfurized by a desulfurization device and dust is removed by a dust collector. After that, it is released into the atmosphere through the chimney, but the temperature of the exhaust gas is usually about 150℃.
Since the temperature is as high as 0.degree. C., there are problems such as the reaction temperature being too high when introduced into the 1-inch desulfurization device, which deteriorates the desulfurization efficiency and may damage the device.

Therefore, conventionally, as shown in the schematic diagram of an exhaust gas desulfurization and dust removal treatment device in FIG. The untreated exhaust gas is passed through the heat exchanger 1 to lower its temperature from, for example, 150°C to 90°C, and then led to the (wet type) desulfurization device 2 for desulfurization treatment;
Next, the exhaust gas whose temperature has dropped to about 50° C. after the desulfurization treatment is guided to a dust collector 3 to remove dust, and then the exhaust gas after the dust removal treatment is passed through the heat exchanger 1 as a heating gas via a blower 4. The temperature should be raised from 50°C to about 110'C, and then the treated exhaust gas at about 110°C should be heated to about 120°C, which is suitable for dissipation into the atmosphere. It was led to chimney 6 and dissipated into the atmosphere.

However, since untreated exhaust gas containing a large amount of dust passes through the heat transfer element of the heat exchanger 1, dust adheres to it over time, and as a result, the heat exchanger 1 loses heat. There is a problem that the exchange efficiency deteriorates and so-called sagging occurs.Moreover, in the case of a rotary heat exchanger, the heat transfer element rotates, and the attached dust is absorbed into the heating gas as it passes through. There was a problem in that dust was dispersed into the atmosphere due to the mixing.

Therefore, this invention solves the above problems, maintains the heat exchange efficiency of the heat exchanger well, and eliminates the need for a casing.
Moreover, it provides a water treatment method for a heat exchanger for sintering exhaust gas treatment that prevents tarst from being mixed into the gas after desulfurization and dust removal treatment. In a heat exchanger for passing sintering exhaust gas after desulfurization and dust removal treatment as a cleaning gas, the heat exchanger is washed with water by spraying water from above, and the washing water from the heat exchanger is used to pass through the heat exchanger. It is characterized in that it is led to a thickener from the lower part of the vessel, and the supernatant water of the thickener is circulated and used as washing water for the heat exchanger.

The present invention will be explained below with reference to examples and drawings.

FIG. 2 is a schematic diagram of the case where the present invention is applied to a rotary heat exchanger, in which 7 is a rotary heat exchanger (hereinafter referred to as a heat exchanger), and 8 is an airtight structure installed at the bottom of the heat exchanger 7. The installed dust hopper 9 is a water sprinkling pipe installed on the upper part of the heat exchanger 7, and the cleaning water sprayed from the water sprinkling pipe 9 washes the heat transfer element of the heat exchanger 7, and then flows into the dust hopper 8. It is designed to be guided by

10 is a water sealing tank for sealing the lower part of the dust hopper 8 with water, and water from the water sealing tank 10 is led to a thickener 12 via a pump 11.

The supernatant water of the thickener 12 is guided to the water sprinkling pipe 9 via a pump 13 as needed,
The precipitate containing dust at the bottom of the thickener 12 is led to the dust separator 15 via the pump 14, where the dust is removed and the water after the dust removal is sent to the thickener 12. It is set to be returned.

16 is a duct for the temperature-lowering gas of the heat exchanger 7, 17 is a duct for the temperature-raising gas, and the water sprinkler pipe 9 is located in the duct N6, 17 attached to the upper part of the heat exchanger 7.

With such a configuration, the heat transfer element of the heat exchanger 7 is cleaned by sprinkling water from the water sprinkler pipe 9 as necessary, and if dust is attached, it is washed off.
The water reaches the dust tanker 12 via the dust hopper 8 and is recovered by the dust separator 15, while the water from which the dust has been removed is again sent to the sprinkler pipe 9 and used as washing water.

As explained above,. In this invention, since the heat transfer element is appropriately washed with washing water, the heat exchange efficiency does not decrease and there is no fear that trapped dust will be dissipated into the atmosphere, and water can be used effectively by being recycled. be able to.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an exhaust gas desulfurization and dust removal treatment apparatus, and FIG. 2 is a schematic diagram of the present invention applied to a rotary heat exchanger. 1, 7... Heat exchanger, 2... Desulfurizer, 3... Dust collector, 4... Blower, 5... Reheating furnace, 6... Chimney, 8... Storm hopper - 9... Water pipe, 10
...Water seal tank, 11,13.14...Pump, 12.
...Sickener, 15...Dust separator, 16.17
···duct.

Claims (1)

[Scope of Claims] 1. The untreated sintered exhaust gas is passed through as a temperature-lowering gas, and the sintered exhaust gas after desulfurization and dust removal treatment is passed through as a temperature-raising gas, and the high-temperature untreated sintered exhaust gas is brought to a predetermined temperature. In a heat exchanger for lowering the temperature, the inside of the heat exchanger is washed with water by spraying water from the upper part thereof, and the washing water after washing the inside of the heat exchanger is led to a thickener from the lower part of the heat exchanger. . A water treatment method for a heat exchanger for treating sintered exhaust gas, characterized in that the supernatant water of the thickener is recycled as washing water for the heat exchanger.