KR100862849B1 - A duplex waste water purification apparatus for shaft kiln - Google Patents

Abstract

The present invention rapidly precipitates the slurry contained in the dust collector using its own waste gas in a vertical kiln, and improves the water quality for dust collection to purify and discharge the exhaust gas, thereby significantly reducing air pollution. The present invention relates to a dust collecting secondary purification treatment apparatus for a vertical kiln.

The present invention, in the vertical type kiln for discharging the flue gas generated during the process of manufacturing quicklime using limestone as a stack through a venturi scrubber, the fan is connected to the exhaust through the exhaust gas supply pipe on one side of the stack and discharged from the stack A suction part which draws out part of it; A moisture treatment unit having a demister for treating moisture contained in exhaust gas sucked by the suction unit by gravity settling; A nozzle unit for introducing exhaust gas passing through the moisture treatment unit into the venturi scrubber and continuously reacting calcium hydroxide in the collected wastewater and carbon dioxide in the exhaust gas; and electrically connected to a fan of the suction unit to operate it remotely. It provides a secondary purification treatment apparatus for collecting dust for a vertical kiln comprising a controller.

Limestone, quicklime, venturi scrubbers, vertical kilns, dust collection and purification equipment

Description

Dust collecting secondary purification apparatus for vertical kilns {A DUPLEX WASTE WATER PURIFICATION APPARATUS FOR SHAFT KILN}

1 is an explanatory view showing a vertical kiln according to the prior art;

2 is a detailed view of a venturi scrubber equipped in a vertical kiln according to the prior art;

3 is an explanatory diagram showing an operating state of a venturi scrubber provided in a vertical kiln according to the prior art;

4 is a detailed view showing a configuration in which the dust collecting secondary purification apparatus according to the present invention is mounted in a vertical kiln;

5 is a cross-sectional view showing a state in which a nozzle provided in a dust collecting secondary purification apparatus for a vertical kiln according to the present invention is inserted into a venturi scrubber;

Figure 6 is a flow chart showing the operating state of the dust collecting secondary purification treatment apparatus for a vertical kiln according to the present invention in sequence;

7 is a graph showing the experimental results of the present invention and the prior art.

       <Description of the symbols for the main parts of the drawings>

5 ..... flue gas supply pipe 10 .... suction

12 .... Fan 13 .... Magnifier                 

15 .... Gate Valve 30 .... Moisture Treatment

34 .... Demister 37 .... Suction tube

40 .... Outlet tube 42 .... Inner tube

43 .... level control tank 50 .... nozzle

52 .... Nozzle 55 .... Secondary flue gas supply line

55a .... damper 57 .... tertiary flue gas supply line

57a .... Flexible hose 70 .... Controller

100a, 100b ... Fire Furnace 110 .... Gas Channel

114a, 114b ... Lance 121 ... Venturi Scrubber

124 .... stack 129 .... scrubber cone

132 .... Pump

The present invention relates to a secondary dust purification apparatus for collecting dust used in a vertical kiln for preparing quicklime, and more specifically, to a slurry contained in a dust collector using its own waste gas of a vertical kiln. The present invention relates to a secondary purification treatment apparatus for collecting dust for vertical kilns which can significantly reduce air pollution by rapidly settling) and improving the water quality for dust collection to purify and discharge the exhaust gas.

In general, vertical type kilns 100a and 100b manufacture limestone by heating limestone at a high temperature of 900 ° C. or more for a long time using the heat of combustion of a coke oven gas, which is described in more detail with reference to FIG. 1. The explanation is as follows.

Limestone used as the raw material of quicklime is erected to 40 ~ 80㎜ to wash the foreign matter adhering to the surface, and then charged and discharged for a certain time according to the production amount, and also two kilns in parallel In (100a) and (100b), mutual gas passages (110) are formed, and after completing the charging and discharging cycles, the firing process of supplying the gas as a heat source and the non-firing process of discharging the gas are mutually performed. It is made to replace repeatedly.

In addition, the firing furnaces 100a and 100b are each provided with a charging device, a combustion device, a cooling device and a dispensing device. In each of the firing furnaces 100a and 100b, preheating, firing, and cooling zones are formed to form the limestone. After 20 hours of decarbonation reaction, that is, heat is applied to limestone to release carbon dioxide, the main component, and then slowly lowered to produce pure quicklime.

1 is a view showing a flue gas treatment process in the manufacture of quicklime in the conventional vertical kiln (100a, 100b). In FIG. 1, the combustion and cooling devices provided in the kiln are omitted, and the fuel gas supplied through the lances 114a and 114b and the combustion air supplied through the duct 115 are fired on the firing side 100a. (The other kiln is in the air) and calcined by heating limestone for a predetermined time, and the hot exhaust gas generated at this time is discharged to the non-fired side kiln 100b through the chanel 110.

The exhaust gas continuously discharged through this repetitive process contains a large amount of toxic gas (CO2) and dust (Dust), so that the dust contained in the flue gas as well as the toxic gas (CO2) and the toxic gas (CO2) are completely treated before being released into the atmosphere. It is legally mandated to do so.

The exhaust gas discharged here is impregnated with dust, and as shown in FIG. 2, a large amount of dust removal water (dust collecting) is sprayed by the nozzle 127 by a venturi scrubber 121, which is a wet dust collecting device, to generate dust. This exhaust gas is discharged to the atmosphere through the stack 124. In the venturi scrubber 121, the dust is filtered by the scrubber cone part 129 at the lower side of the stack 124, and the dust is resupplied to the nozzle 127 through the pump 132.

The dust collected after dust removal is PH of 8.1 ~ 9.5, SS is 740 ~ 820 and is alkaline and contains a large amount of suspended solids such as calcium hydroxide (Ca (OH) 2: lime water reacted with lime and water). It can be seen from the experiment that contains 15 to 20% CO2.

Therefore, in the venturi scrubber 121, when the dust collected by the conventional instantaneous sedimentation is reused, a large amount of foreign matter is contained, and even when the dust is used, it is found that the foreign matter dust collection in the exhaust gas becomes poor. Can be.

Meanwhile, in recent years, various apparatuses and methods for treating flue gas generated during quicklime manufacturing have been actively developed.

In this regard, in the conventional method for treating flue-gas generated during the quicklime manufacturing process, the “Scrubber Dust Collector Using Steam Injection and Condensation Effect” of Korean Utility Model Application No. 1997-00042330 uses high-pressure steam and water at the inlet of the venturi. The technique of improving the exhaust concentration of dust in exhaust gas by improving the performance of a venturi part by spraying is disclosed.

However, such a conventional technique has a large amount of coating formed in the venturi inlet duct due to the collision of high-pressure steam and exhaust gas, which requires frequent cleaning, thereby reducing productivity due to lower operation rate, and simultaneously removing harmful gas contained in the exhaust gas. There is a problem that cannot be done.

In addition, as another conventional technology, the "scrubber with ultrasonic vapor spraying device" of Korean Utility Model Application No. 1997-00029672 attaches the ultrasonic steam spraying device to the scrubber and sprays the absorbent liquid in the vapor state to maximize the absorption of harmful substances. This technology, but this is a large installation cost when applied to large-capacity equipment, there is a problem that can not function properly due to the slurry management.

In addition, as another conventional technology, "exhaust gas cooling and dust collecting device" of Korean Utility Model Application No. 1998-00024945 relates to a device for cooling and collecting exhaust gas generated during converter blown, and adopts a water-cooled tube method and an electric dust collecting method. It is designed to control the temperature of the exhaust gas in the chamber and to separate and remove dust from the exhaust gas, but this technology is applied to dry exhaust gas, and this process contains a large amount of moisture and dust in the exhaust gas, making it difficult to use for performance.

Therefore, in the related art, in order to reduce the generation of dust (Dsut), especially in the flue-gas of the vertical type kiln, there are frequent cases of reducing the daily quicklime production of the kiln or pausing the process.

Therefore, the present inventors have applied for the "secondary vibration damping device in the vertical type kiln" of the Republic of Korea Patent Application No. 2000-00042967 in order to solve such a problem of the prior art and use it in actual vertical type kiln to stack the stack (Stack By exhausting the exhaust gas discharged from the) 124 by the blower to the scrubber cone portion 129 to reduce the dust in the exhaust gas efficiently.

However, the previously filed method has a limitation in removing dust discharged from a vertical kiln, and also increases the use of water used for wet dust collection and inevitably releases carbon dioxide when producing limestone as quicklime. In the process, there was an urgent problem to be prepared for the new regulation of carbon emission.

In order to solve the problems of the prior art as described above, the present invention, by inputting limestone in a vertical kiln for the purpose to effectively reduce dust and carbon dioxide in the flue gas generated in the process of calcining the quicklime at the same time collecting dust The present invention aims to provide a dust collecting secondary purification treatment device for a vertical kiln, which significantly improves dust collecting performance without using a large amount of gas and also solves a problem of cost burden and environmental pollution by reducing carbon dioxide emission.

In order to achieve the above object, the present invention, in the vertical kiln for discharging the flue gas generated during the process of manufacturing quicklime using limestone as a stack through a venturi scrubber

A suction unit for connecting a fan through an exhaust gas supply pipe at one side of the stack to draw a part of the exhaust gas discharged from the stack; A moisture treatment unit having a demister for treating moisture contained in exhaust gas sucked by the suction unit by gravity settling; A nozzle unit for introducing exhaust gas passing through the moisture treatment unit into the venturi scrubber and continuously reacting calcium hydroxide in the collected wastewater and carbon dioxide in the exhaust gas; and electrically connected to a fan of the suction unit to operate it remotely. By providing a dust collecting secondary purification treatment apparatus for a vertical kiln, characterized in that it comprises a controller.

Hereinafter, with reference to the accompanying drawings will be described in more detail the dust collecting secondary purification treatment apparatus for a vertical kiln according to the present invention.

Figure 4 is a perspective view showing a state of use of the exhaust gas treatment dust-collecting secondary purification treatment apparatus provided in the vertical kiln according to the present invention, Figure 5 is a cross-sectional view showing a flue gas inlet state of the scrubber chanel of Figure 4, It is a flowchart which shows the control method of the dust collecting secondary purification processing apparatus which concerns on this invention.

In the dust collecting secondary purification treatment apparatus 1 for the vertical kiln according to the present invention, as illustrated in FIG. 4, a fan 12 is connected to one side of the stack 124 through an exhaust gas supply pipe 5 to form a stack ( It has a suction part 10 which takes out a part of exhaust gas discharged | emitted from 124.

The suction unit 10 sucks the exhaust gas of the vertical kilns 100a and 100b containing 15 to 20% of CO 2, which is first wet-damped and discharged from the stack 124 using the high pressure fan 12. It is.

The suction unit 10 is the size of the exhaust gas supply pipe (5) is determined according to the exhaust gas flow rate, the stack 124 and the connection portion of the supply pipe (5) is fixed using an expansion tube (13), to one side Is equipped with a gate valve 15 for the purpose of shutting off the exhaust gas during repair work. In addition, the flange 17 is welded and mounted on the opposite end to facilitate connection with the moisture processing unit 30.

In addition, the dust-collecting secondary purification treatment apparatus 1 for the vertical kiln of the present invention is a moisture treatment unit having a demister 34 for treating moisture contained in the exhaust gas sucked by the suction unit 10 by gravity settling. Bar 30 is provided, the moisture treatment unit 30 is a right angle to the outer circumferential surface of the hollow demister 34 so that the exhaust gas flows into the cylindrical demister 34 along the inner contact surface, the suction pipe ( 37) is welded to the end of the flange to connect the suction pipe 37 to the exhaust gas supply pipe (5).

In addition, the inner tube 42 is integrally installed in the outlet tube 40 of the demister 34, and the length of the inner tube 42 is inserted downward and fixed to 75% of the demister 34.

Thus, since the length of the inner pipe 42 is extended downward by 75%, the water contained in the exhaust gas is stably separated by gravity sedimentation in the process of discharging the exhaust gas downward from the upper side to the lower side and discharged through the inner pipe 42. will be.

In addition, the drain pipe 34a is connected to the bottom of the demister 34, and a water level control tank 43 is installed at one side thereof, and a ball valve (not shown) that is easy to operate is installed in the middle thereof. It is preferable.                     

In addition, the present invention has a nozzle unit 50 for flowing the exhaust gas passing through the moisture treatment unit 30 into the venturi scrubber 121 to continuously react the calcium hydroxide of the wastewater and carbon dioxide of the exhaust gas. Bar, the nozzle unit 50 is boosted to the pressure required to exhaust gas using the suction fan 12, after the first wet damping, the channel of the venturi scrubber 121, which is a passage through which dust collecting flows, the channel (121a) To be introduced through the nozzle 52.

The nozzle unit 50 is connected to the secondary exhaust gas supply pipe 55 at the end of the gas outlet pipe 40 of the demister 34 is fastened to the inlet of the suction fan 12, the middle of the damper for flow control 55a is mounted.

In addition, the suction fan 12 is fixed to the ground by the fixing member 12a, the third exhaust gas supply pipe 57 is also fastened to this outlet side is installed to the chanel 121a of the scrubber 121, The end of the primary exhaust gas supply pipe 57 is made of a flexible hose 57a.

Thus, vibration from the fan 12 is not transmitted to the venturi scrubber 121.

The chanel 121a is formed to have a sufficient depth (700 to 1200 mm) to insert the nozzle 52 so that the cylindrical nozzle 52 can be inserted into and fixed therein. Meanwhile, the present invention includes a controller 70 electrically connected to the fan 12 and the damper 55a of the suction unit 10 to remotely operate the controller 70, and the controller 70 is an instrument controller (not shown). The dust collector is configured in the cab so that the present invention can be operated by the operation program of the vertical kilns 100a and 100b, and is supplied to the vertical kilns 100a and 100b under the control of the instrumentation controller. It is provided with a screen display (70a) for outputting the information related to the water quality (PH, etc.) on the screen.

The operation and effect of the dust collecting secondary purification apparatus 1 for a vertical kiln according to the present invention configured as described above will be described in detail with reference to FIG. 6 as follows.

The vertical firing furnace (100a) (100b) is composed of two furnaces, as in step 90, in the furnace (100a) of one side, the coke oven gas and the combustion air is a heat source for firing quicklime In addition, the other furnace (100b) discharges the combustion gas injected during the firing, this operation is operated while being periodically replaced with each other in a constant cycle according to the production amount.

The exhaust gas discharged here is impregnated with dust, and as in step 91, a large amount of dust removal water (dust collecting) is sprayed by the nozzle 52 by the venturi scrubber 121, which is a wet dust collecting device, to remove dust. This exhaust gas is discharged to the atmosphere through the stack 124.

The dust collected after dust removal is PH of 8.1 ~ 9.5, SS is 740 ~ 820 and is alkaline and contains a large amount of suspended solids such as calcium hydroxide (Ca (OH) 2: lime water reacted with lime and water). Contains 15-20% CO2.

Therefore, in the present invention, the suction fan of the suction unit 10 of the inlet 10 in the exhaust gas stack 124 is known to have good cohesion with the suspended matter contained in the dust collected and discharged in the exhaust gas. Inhalation by (12) passes through the demister 34 of the moisture removal unit 30 to remove moisture contained in the exhaust gas.

Then, in the next step 93, the suction fan 12 is passed to boost the exhaust gas to an appropriate pressure (600 to 1200 mmH 2 O), and then, through the exhaust gas supply pipe 57, a plurality of nozzles ( 52) to be introduced into the front side chanel 121a of the venturi scrubber, and the quality of dust collection is improved by the following reaction formula in the channel 121a.

1) Quicklime production formula: CaCO ₃ ---> CaO + CO ₂

2) Hydration scheme of quicklime in collecting dust: CaO + H ₂ O ---> Ca (OH) ₂

3) Precipitation Scheme: Ca (OH) ₂ + CO ₂ ----> CaCO ₃ + H ₂ O

As shown in Scheme 3), carbon dioxide can be easily reacted with calcium hydroxide contained in a large amount of dust to form a heavy calcium carbonate, thereby facilitating precipitation.

In addition, in order to remove moisture easily while exhaust gas passes through the demister 34 as in step 94, a water level of about 300 to 400 mm is required, and above that, an automatic flow through the overflow pipe 34a. Discharged.

A series of experiments were conducted to more specifically grasp the effect of the present invention operated by this process.

In this experiment, vertical kilns (100a) (100b) were used to produce 300 tons of quicklime per day, and the effective flue gas volume was discharged to 12500 Nm3 / Hr from the kilns (100a) (100b). 15.5%. In such exhaust gas, when the exhaust gas is sucked as a fan 12 at 65 Nm 3 / Hr, and re-injected into the venturi scrubber 121 to enter the discharged dust, the change in hydrogen ion concentration and turbidity is shown in FIG. 7. Comparison is shown as a graph.

As can be seen from the graph of FIG. 7, according to the present invention, it was found that the hydrogen ion concentration and turbidity were significantly lowered in the dust collection than the conventional method.

According to the present invention on the basis of the experimental results, the water quality of the dust collection by vertical recovery of the carbon dioxide contained in the exhaust gas in the vertical calcining furnace (100a, 100b) for producing quicklime and supplying it again to the dust collector of the venturi scrubber 121 You can see the improvement of dust collection effect and the water quality improvement of dust collection.

According to the present invention as described above, in the vertical calcining furnace (100a, 100b) used in the quicklime manufacturing process, the carbon dioxide in the exhaust gas is reacted with the calcium hydroxide of the coagulation to precipitate into heavy calcium carbonate, which causes The slurry contained is quickly precipitated.

Therefore, by removing the slurry from the dust collection, the water quality for dust collection is improved, and the dust quality with improved water quality is better to purify and discharge the exhaust gas, so that a large amount of dust collection used for dust collection of the exhaust gas is not used. It is possible to significantly improve the dust collection performance of the dust contained in the flue gas without.

In addition, by reducing the emission of carbon dioxide in the exhaust gas, a very useful effect of simultaneously solving the problems of cost burden and environmental pollution is obtained.

Claims (4)

In the vertical type kiln to discharge the flue gas generated during the process of manufacturing quicklime using limestone to the stack 124 through the venturi scrubber 121, A suction unit 10 connected to a fan 12 through an exhaust gas supply pipe 5 at one side of the stack 124 to draw a part of the exhaust gas discharged from the stack 124; A moisture processing unit (30) having a demister (34) for treating moisture contained in exhaust gas sucked by the suction unit (10) by gravity settling; A nozzle unit (50) for continuously introducing the exhaust gas passing through the moisture treatment unit (30) into the venturi scrubber (121) to continuously react calcium hydroxide in the collected wastewater and carbon dioxide in the exhaust gas; and And a controller (70) electrically connected to the fan (12) of the suction unit (10) to operate it remotely. According to claim 1, wherein the demister 34 is located on the front side of the fan 12, the inner tube 42 is integrally installed in the outlet tube 40, the length of the inner tube 42 is 75% Dust collecting secondary purification treatment device for a vertical kiln, characterized in that fixed to insert downward. The end of the tertiary exhaust gas supply pipe (57) provided at the outlet side of the suction fan (12) is made of a flexible hose (57a), so that vibration from the fan (12) is prevented. 121) dust collecting secondary purification treatment apparatus for a vertical kiln, characterized in that not configured to be delivered to. According to claim 1, The suction fan 12 boosts the exhaust gas to a pressure of 600 ~ 1200mmH2O, the venturi through a plurality of nozzles 52 of the nozzle unit 50 through the exhaust gas supply pipe 57 Dust collecting secondary purification treatment apparatus for a vertical kiln, characterized in that supplied to the scrubber (121).

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