JPS58202016A - Method and apparatus for recovering soda ash - Google Patents

Abstract

PURPOSE:To prevent the clogging and the corrosion of a dust collection apparatus, by a method wherein a gas is sent into the dust collecting apparatus while the temp. and the moisture of the gas are regulated during a period for introducing the gas into the dust collecting apparatus and air from the outside of a furnace heated by a heat accumulator is introduced into the dust collecting apparatus during a period not introducing the gas into said dust collecting apparatus to constantly adjust the temp. in the dust collecting apparatus. CONSTITUTION:A dust-containing gas from an oxygen steel manufacturing furnace 1 is mainly introduced into a heat recovery device 6 and the part thereof is introduced into a heat accumulator 7 to be heated by the heat accumulating part 7b thereof. These gases are further guided to an evaporative cooling tower 10 to lower the temp. thereof to a set temp. while simultaneously humidified and soda ash and other dusts in the exhaust gas are recovered by a dry dust collecting apparatus 3. When the generation of a high temp. gas in the oxygen steel manufacturing furnace 1 is stopped, in order to prevent the lowering in the temp. of the dry dust collecting apparatus 3, an auxiliary blower 4b is operated to guide air in the vicinity of the furnace 1 to the heat accumulating part 7b and heated to a high temp. to be introduced into the dust collecting apparatus 3.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and an apparatus for recovering sorter ash from high-temperature exhaust gas that is intermittently generated in exhaust gas from oxygen steelmaking furnaces, etc., contained in sorter ash-depleted multi-noodles.

The exhaust gas for oxygen steelmaking furnaces contains a large amount of sorter ash (Na2CO,
)% - may be included with other lists.

Sorter ash absorbs water loss in the gas and easily deliquesces (when deliquesced, it becomes a significant contaminant (adhesion) together with other ash, which can lead to blockage of equipment flow paths such as dust collectors and severe corrosion). There is a fear.

For example, in Figure 1, (01) is an oxygen steelmaking furnace, (02) is a gas pipe, and (03) is an oxygen steelmaking furnace.
is an electric precipitator.

A dry dust collector such as a butterfilter (04) is a ventilator, and in the oxygen steelmaking furnace (01), gas containing multi-violet sorter ash and other dust is generated intermittently. FIG. 2 shows such a dust-containing gas generation situation, in which dust-containing scum is generated intermittently twice as shown by the hatched area with respect to the time indicated on the abscissa. Here T1 is around 20 minutes tTt
is around 20 minutes or more. Also, the gas temperature is i
oo.

Around C, the moisture in the gas is close to zero.

When performing dry dust collection on the dust-containing exhaust gases mentioned above, it is necessary to appropriately adjust the temperature and moisture content of the gas and target solids in the dust collector in order to sufficiently maintain the performance and equipment of the dust collector. However, until now, there was no solid knowledge or concrete method for this.

Therefore, the inventors of the present invention have developed a method that contains a large amount of sorter ash,
As a result of 111 years of research into technology for effectively recovering ash from intermittent high-temperature gases, we have discovered the following.

FIG. 5 shows the relationship between gas temperature and spark generation voltage in an electrostatic precipitator. As can be seen from the figure, if the gas temperature is too high, sparks are likely to occur, resulting in a low operating voltage (and therefore, dust collection performance). Also, if there is little moisture in the gas, sparks will occur. Therefore, if an electrostatic precipitator is not used, appropriate temperature and moisture must be maintained several times.

Next, FIG. 4 shows an example of the relationship among the deliquescence of the sorter ash, the condensation of moisture in the gas, and the dust collection gas conditions. Sorta Ash (N Town C08
) turns into Na2CO3 hydrated salt in humid gas, which has deliquescent properties. The saturated vapor pressure p of this aqueous solution is the water vapor partial pressure p of the dregs. It is known that approximately 80% of the Therefore, the deliquescence of Na1CO3 hydrate is:
If it is based on po k standard, then p. −p as p. / = p. This can be avoided by keeping the temperature (dew point) above the temperature (dew point) corresponding to po' determined to be 108. Curve A in FIG. 4 depicts the relationship between the gas temperature, which is safely increased by 200 degrees from the temperature thus determined, and the moisture content in the gas. There is a risk that deliquescence will occur on the lower temperature side (shaded area) than curve iA, but it can be considered that deliquescence will not occur on the higher temperature side.

Curve B in the figure is a graph depicting the relationship between the waste temperature and the moisture in the waste, which is approximately 25 C higher than the dew point, which corresponds to the vapor pressure of the moisture in the gas, and almost coincides with the second curve A.

Next, curve C in Fig. 4 assumes that the generated gas temperature is 1000.
In the case of C, there is no approximate estimate of the condenser outlet temperature and moisture that are simultaneously determined when cooling to an arbitrary temperature on curve C by water addition and evaporation.

D shows the case where the moisture content in the waste was adjusted to be constant (10%), and the gas temperature was optionally adjusted by other cooling* (for example, air mixing). It is considered appropriate to operate a dry electrostatic precipitator in the shaded area E between curves C and D in order to maintain normal charge, but in the case of a back filter,
In terms of heat resistance, it will be limited to around 200C.

Here, as an example of scum with a lot of water, 20DC of 9 curve C
When collecting dust with It is the largest compared to (a), (tsul, (jll, taste), ri).Also, when there is little water, 20D
If it is C, the corresponding temperature difference will be (), and the safety when the temperature drops is greater than in (a) above, but it cannot be said to be sufficiently large.

In the case of an electrostatic precipitator, it is possible that a larger amount of moisture in the gas is required than in a curved one, so the safety level is even lower (like this).

It can be seen from Figure 4 that it is necessary to use an effective heat retaining means to prevent the temperature of the dust collector from dropping.

This will be further explained with reference to FIG.

FIG. 5 schematically shows temporal changes in various quantities in the dry dust collector (05), with the explanations of FIGS. 1 and 4 broken out. Since high-temperature gas is generated intermittently, one generation stop time is T.

The gas temperature and moisture will decrease. If the gas temperature is lower than the temperature indicated by curve A (Fig. 4) corresponding to the moisture content, the gas temperature becomes a deliquescent region shown by diagonal lines in Fig. 2, which is dangerous.

As is clear from the above explanation, when collecting dust using the dry method, the gas temperature and moisture content in the gas during 2nd ventilation (T1) must be appropriately determined.
It is necessary to adjust the temperature and maintain the internal temperature of the dust collector at a predetermined temperature during non-ventilation (T).

The present invention has been developed in view of the above-mentioned problems. 1. Oxygen steelmaking which is generated intermittently and contains a large amount of sorter ash, and when sorter ash is dry-recovered from the furnace exhaust gas, contamination of the dry-type dust collector.

This method was developed to control the gas temperature and moisture content to prevent corrosion, and to recover sorter ash in a dry state from the gas containing a large amount of high-temperature sorter ash that is intermittently discharged from an oxygen steelmaking furnace. During the period when the gas is introduced into the gaseous dust collector, the gas temperature and the moisture content in the gas are adjusted to a predetermined value before the gas is introduced into the heat storage device (at least some of the waste is introduced into the heat storage device). During periods when the dust equipment is not connected,
A sorter ash recovery method, and an oxygen steelmaking furnace, characterized in that the air outside the furnace is heated by passing through the above-mentioned heat storage device, and then guided to the above-mentioned dust collector, and the internal temperature of the dust collector is adjusted to a predetermined value. The sorter ash is recovered in a dry state from the high-temperature sorter ash containing a large amount of scum that is intermittently discharged from the oxygen steelmaking furnace, and there is a heat storage device downstream of the oxygen steelmaking furnace.

This paper proposes a sorter ash recovery device characterized by sequential installation of a gas cooler and a dry dust collector.

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 6 is a schematic diagram illustrating a secure embodiment of the present invention. In the figure, i11 is an oxygen steelmaking furnace in which high-temperature gas containing sorter ash is intermittently generated (21 is a gas conduit leading to the waste scrap of the oxygen steelmaking furnace. (5a) and (5b) are branched from the above gas conduit t2+. , one is a heat recovery device such as a boiler (610 inlet,
The other is a heat storage device (at the entrance of 71).

The pipes (8m) and (8b) communicating with each other are distribution valves provided in the pipes (5a) and tsb), respectively. The heat storage device (71) is connected to the dust removal section (7a) and the heat storage section (7b) filled with heat storage material. It merges with the outlet pipe (9b) and communicates with the inlet of the evaporative cooling tower, and the outlet pipe α11 of the evaporative cooling tower 111m.
communicates with the inlet of a dry dust collector (3) such as an electrostatic precipitator,
A cold air supply pipe az opens to the pipe (111). , ab) open to gas utilization equipment or the atmosphere via v.+131
and 04) are a water injection control valve and an air injection control valve respectively provided in the cooling water shortage supply pipe to the evaporative cooling tower αυ and the cold air supply pipe [1X5]. Also a9
is a temperature detector *f16+ is a temperature setting/transmitter.

Evaporative cooling El tower α・, water injection control valve fi11. Temperature detector [
151 and the temperature setting/transmitter a61, conventionally known devices can be used.

In a sorter ash recovery device having such a configuration.

The dust-containing exhaust gas that comes out of the oxygen steelmaking furnace i11' is mainly guided to the heat recovery device (61), and a part of it is guided to the heat storage device (71) for heat recovery. After rough dust removal in section (7a), heat storage section (7b)
The heat storage material is heated, and the water husks are cooled. Distribution of ventilation to the heat recovery device (61) and heat storage device (71)
Perform according to a) and (8b). The exhaust gas cooled by the heat recovery device (61) and the heat storage device (7) is transferred to the evaporative cooling tower θG.
At this point, the temperature is further lowered to a preset temperature, and at the same time, it is humidified and humidified. This temperature adjustment is performed by predetermining the target temperature of the dry dust collector (31) and using the temperature detector [15+, temperature setting/transmitter (161), and water injection control valve 041.

A part of the sorter ash and other dust contained in the exhaust gas is collected in a dry state in the dust removal section (7a) of the heat storage device (7).
Most of it is collected by a dry precipitator (31).If this dry precipitator (31 is an electrostatic precipitator), the gas temperature is 40
0C may be as high as desired, but in the case of a Bata filter, the limit is 250U at most.

When high temperature gas generation in the oxygen steelmaking furnace fi+ stops,
The gas temperature in the dry type dust collector (31) drops rapidly.If the main ventilation fan (4a) continues to operate, low-temperature air passes through the dry type dust collector (31), causing the temperature to drop even faster. , at the same time as gas generation stops, the main ventilator (
4a) is also stopped.

Furthermore, in order to prevent the temperature of the dry dust collector (31) from decreasing as much as possible, the first distribution valve (8a) is closed, and the second distribution valve (8b) is left open and the sub-ventilator (4b) is operated.

Then, the air near the oxygen steelmaking furnace (1) will be transferred to the heat storage (
71, where it becomes high temperature due to the accumulated heat of the heat storage i (7b), and this high temperature air is introduced into the dry type dust collector (3), thereby preventing the temperature of the dry type dust collector from decreasing. In this case, the high temperature air during this period is
) may be specially vented to the atmosphere at the exit. In this embodiment, the temperature of the dry dust collector (3) may be adjusted only by adjusting the ventilation lid using the main ventilator (4a) without installing the subventilator (4b). Due to changes in heat storage amount, etc.

If the temperature of the dry dust collector (31) is not constant and becomes higher than the predetermined temperature, it can be adjusted by increasing the amount of cold air from the cold air supply pipe α2.
Temperature detector a9. Temperature setting/transmitter and air control valve 0
Adjust according to 4). The set temperature of the dry dust collector (3) may be determined in accordance with the explanation given above for FIG. 4.

In this way, in this embodiment, the gas temperature and the moisture content in the gas are adjusted during the gas generation period and the gas generation stop period,
Can retain heat.

Next, FIG. 7 is a schematic diagram showing another embodiment of the present invention. This embodiment is for the case where there is no need for heat recovery, and the heat recovery device (61 pieces) as shown in Fig. 6 is not provided, and a simple gas pipe (5
Only a) is included. In addition, in this embodiment, the cold air supply pipe σ2, which reduces the temperature of the dry dust collector (3) during 2-air ventilation, is used.
This is done using cold air taken in from the And gas humidification is
What happens with the steam injected from the steam injection pipe (171)?

The amount of steam injection is adjusted by a steam control valve 010. If humidification is not required or if other humid gas is used,
This steam injection is unsettling. During the ventilation suspension period, a dry dust collector (31 heat retention method and target temperature setting method are the same as the first embodiment and 1'5j) oo This embodiment requires relatively little humidification during ventilation. This method is effective when the exhaust gas temperature is relatively low.

The choice between the embodiment of FIG. 6 and the embodiment of FIG. 7 may be made, for example, according to the above example in which the embodiment of FIG. 7 is effective. The embodiment of FIG. 6 and the embodiment of the seventh factor are summarized.

They can also be arranged on one yarn path as shown in FIG. The embodiment of FIG. 8 can have the features of the embodiments of FIGS. 6 and 7.

As explained in detail above, (1) according to the sorter ash recovery method and apparatus of the present invention, (2) when the sorter ash is collected dryly from the oxygen steelmaking furnace exhaust gas that is intermittently generated and contains a large amount of sorter ash, the gas generation period is During both the period and the gas generation stop period, it is possible to effectively control the temperature of the dust in the dry dust collector and/or the moisture content in the gas, and to effectively prevent the dry dust collector from becoming contaminated or clogged. It is extremely useful industrially because corrosion can be prevented.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of the oxygen steelmaking furnace gas processing equipment that was designated as a subsidiary, Figure 2 is a diagram schematically showing the intermittent generation of the gas, and Figure 6 is the gas temperature and sparks in the electrostatic precipitator. A diagram showing the relationship with the generated voltage is not shown. Figure 4 shows deliquescence of sorter ash and condensation of moisture in gas. A diagram showing an example of the relationship between dust collecting gas conditions, FIG. 5 is a diagram schematically showing changes in various quantities in a dry dust collector over time, and FIG. 6 is a schematic diagram showing a reliable implementation of the present invention. FIG. 7 is a schematic diagram showing another embodiment of the present invention, and FIG. 8 is a schematic diagram showing still another embodiment of the present invention. (01), III...Oxygen steelmaking furnace; (02), +21
...Gas pipe; (03), +31...Dry dust collector; (04)...Ventilator; (4a)...Main ventilator; (4b)...Side ventilation @;( 5a), (5b), (
9a), (9b), ul'-pipe line; (6)... heat recovery device; (7)... heat storage device; (7m)... insect removal section; (7
b)...Heat storage part; (8a), (8b)--Distribution valve; 0ω...Evaporative cooling bath;α2...Cold air supply pipe;
03... Water injection control valve; 041... Air injection control valve: fi
ri...Temperature detector: mark a...Temperature setting/transmitter; 0
7)...Steam injection pipe; 0 crossing...steam control valve.

Claims (2)

[Claims] (1) In a method of recovering sorter ash in a dry state from a gas containing a large amount of crystalline sorter ash that is intermittently discharged from a seismic steelmaking furnace, the above gas is guided to a dust collector (during the period, the A small amount of the gas (some of it passes through the heat storage device, and then all of the gas is introduced into the dust collector (beforehand, the gas temperature and moisture content in the gas are adjusted to predetermined values, and the gas is passed through the dust collector). During the period when the air is not introduced into the apparatus, the air outside the furnace is heated through the heat storage device, and then introduced into the dust collector, and the internal temperature of the dust collector is adjusted to a predetermined value. Method. (2) In a device that recovers sorter ash in a dry state from a gas containing a large amount of high-temperature sorter ash that is intermittently discharged from an oxygen steelmaking furnace, a heat storage device is installed downstream of the upper Kt acid cable steelmaking furnace;
A sorter ash recovery device characterized by sequentially providing a gas cooler and/or a gas humidifier and a dry dust collector.