KR20060071542A - Improvement of gas permability in preheater of rotary kiln calciner - Google Patents

Abstract

The present invention is a rotary kiln type ore kiln comprising a rotary kiln, a cooling device, an ore preheater, a kiln ore loading inlet duct, wherein an exhaust gas discharge duct 35 for discharging exhaust gas from an upper end of the ore preheater is installed, Water cooling heat exchanger (70) is installed on one side of the ore entrance inlet duct, and cooled to the exhaust gas temperature discharged after the heat exchange bleeding is recovered from the ore preheater (30) with high temperature exhaust gas. Rotating kiln ore blast furnace, characterized in that the mounting as a gist.

Rotary Kiln

Description

Rotary kiln-type ore kiln with improved vents {Improvement of gas permability in preheater of rotary kiln calciner}

1 is a general rotary kiln type ore kiln facility configuration diagram.

Figure 2 is a conventional lime kiln ore preheater structure and rotary kiln ore kiln.

Figure 3 is a rotary kiln type ore blast furnace configuration comprising the exhaust gas by-pass piping breathable improvement system according to the present invention.

Figure 4 is a block diagram of a heat exchanger for exhaust gas cooling devised in the present invention.

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

1. Fired raw material ore 2. Fluid fuel (COG, LNG, heavy oil, etc.)

3. Air (for combustion and cooling) 4. Furnace flue gas

2a.2b, Fluid Fuel Supply and Flow Meters

3a, 3b, 3c.3d air and flue gas mixture gas supply pressure gauge and flow meter

4a, 4b, 4c, 4d kiln flue gas supply pressure gauge and flow meter

10: rotary kiln body 15: burner system for heat source supply

20: calcination cooling device 25a, 25b: intake fan

30: ore preheater 31: kiln ore loading inlet duct                 

35: ore preheater exhaust gas discharge piping

40: Multicyclone

45: ID Fan 46: Exhaust Fan Control Denper

47: Ventrury scrubber Inlet Duct

50: venturi scrubber 51: venturi scrubber control damper (Damper)

52: venturi scrubber exhaust duct

53: Cyclonic separator

60: By-pass exhaust pipe gas cooling jacket

70: By-pass flue gas heat exchanger

71: high temperature exhaust gas cooling piping in the water-cooled heat exchanger

72: water-cooled heat exchanger

73: dust collection chamber containing gas

66,67,68: By-pass exhaust gas cooling cooling water piping

75: By-pass flue gas piping 76a, 76b: by-pass flue gas piping opening and closing valve

80: Dust Storage Hopper

81: By-Pass Exhaust Gas Cyclone Heat Exchanger

100: stack

The present invention relates to improving the air permeability of a rotary kiln type ore kiln with a shaft type ore preheater. The core device of the rotary kiln type ore kiln is to install a bypass piping system to improve the air permeability of the ore preheater. The present invention relates to a rotary kiln type ore kiln with improved ventilation to smooth the discharge of generated flue-gas and to reduce the formation of deposits in the furnace by separating and discharging particulate gas containing exhaust gas through a bypass pipe heat exchanger.

In the lime-fired furnace for producing quicklime or light dolomite by firing fine limestone and dolomite, which are mined in mines, combustion of fluid fuel such as LNG and coke oven gas (COG) or heavy oil, which are commonly used as a source of plastic energy. During the process, a large amount of high-temperature exhaust gas is discharged. In order to recover the high-temperature sensible heat contained in the exhaust gas, the heat is generally recovered through a shaft-type ore preheater, and then discharged to the outside through a stack through a dust collector. At this time, the ore preheater is blocked due to the exhaust gas-containing fine ore, and the kiln kiln flue gas cannot be discharged smoothly.

Therefore, in the present invention, the ore preheater bypasses the ore preheater so that the exhaust gas can be smoothly recovered from the ore preheater while the high-temperature flue gas sensitized in the ore preheater is composed of the ore preheater and the rotary kiln kiln. The invention relates to a rotary kiln ore kiln and a method of operation thereof including a by-pass pipe.

In general, in the case of lime calcination furnaces that make quicklime or light dolomite from limestone or dolomite, rotary kiln is generally used for the treatment of particulate ore with a diameter of 0 to 35mm, and it is necessary for the process of calcining ore in the kiln. Gas and heavy oil burners are used to supply large amounts of energy.

At this time, the air is primarily supplied as a combustion gas along with the fuel to be mixed with the burner at the burner front end to maintain the uniform temperature in the furnace, so that the ore is easily calcined. In addition, a large amount of room temperature air is supplied onto the product hopper (product cooling device) for the purpose of cooling the product discharged after firing, and this cooling air passes through the kiln and acts as an excess of secondary combustion air, causing a high temperature combustion gas. In addition, it is discharged to the outside through the ore preheater, in this case is sucked by the exhaust fan for smooth discharge is discharged through the stack through the wet cleaning equipment.

As shown in FIG. 1, the structure of the rotary kiln used for calcination of the ore has a burner 11 positioned horizontally to the center of the kiln 10, where fuel and air are supplied to burn at the burner front end, and thus 5 to 10 m in length. As the flame is formed in the furnace, the atmosphere in the furnace is kept constant at about 1000 to 1100 ℃ as the ore firing temperature, and the ore (1) moves downwards while the kiln rotates at a constant speed and the plastic reaction proceeds uniformly. At this time, the generated flue gas is discharged to the ore entrance in the direction of ore and countercurrent flow, and then heat exchanged while passing through a shaft-type ore preheater that preheats the ore charged from the charging hopper at a temperature of about 1000 ° C. It is discharged to the outside through the stack 100 through a dust collector such as cyclone and venturi scrubber in a state separated from 280 ~ 350 ℃. In the process of exhausting the exhaust gas, the exhaust fan strongly suctions the exhaust gas in the furnace at the rear end of the ore preheater, and the ore is substantially differentiated during the firing process in the furnace. Being is inevitable.

However, during the long operation, the derivative passes through the shaft-type ore preheater in front of the rotary kiln and is discharged through the exhaust fan to the stack.

As it accumulates in the fixed-bed ore preheater by the suction action, it has a chronic problem of blocking pores and preventing gas flow. As a result, a large amount of fines remaining due to the disturbance of flue gas discharge in the furnace makes it impossible to supply a sufficient amount of energy source in the furnace, which not only degrades ore plastic quality but also fundamentally reduces productivity relative to capacity. do.

In addition, if the high temperature is formed on the furnace wall while the fine powder stays in the furnace and the burner flame shape does not extend horizontally while the flue gas cannot be discharged from the furnace smoothly, it is one of the chronic problems of reducing the productivity of the rotary kiln kiln. It causes the obstacle to form one of the furnace attachments and provides the cause to prevent facility operation.

Therefore, many attempts have been made to solve such an obstacle in exhaust gas emission, but the cause has not been clearly identified, and various secondary technologies such as suppressing the formation of deposits such as fine powder removal at the rotary kiln ore loading have been proposed.

 The present invention is to solve the problems as described above, in the rotary kiln type lime firing furnace for producing quicklime or light dolomite by firing fine limestone and dolomite mined in the mine in the shaft type ore preheater In order to improve the problem of worsening breathability by blocking the gap between the ores, the breathability is deteriorated due to the differentiation by installing the by-pass piping connecting the rotary kiln ore entrance and the ore preheater flue gas exhaust pipe, which is an area that worsens the breathability. Since the pressure loss of the shaft-type ore preheater is alleviated, not only the effect of improving air permeability, but also the exhaust fan in the rotary kiln can be discharged by bypassing the ore preheater directly by the exhaust fan. By solving the obstacles caused by the one-way exhaust gas discharge of the shaft-type ore preheater, it is aimed at preventing burner flame shape and forming deposits due to fine particles remaining in the furnace.

Hereinafter, the present invention will be described with reference to the accompanying drawings.

In the present invention, in firing ore raw materials containing a large amount of fine powder, such as fine limestone, dolomite, and cement manufacturing clinker, such as a rotary kiln type ore kiln, preheating the recovered ore in the furnace It is characterized by installing by-pass piping bypassing the shaft-type ore preheater to improve the ventilation of the ore preheater and to smoothly discharge the exhaust gas from the rotary kiln type kiln.

The basic configuration of the ore preheater by-pass piping system in the present invention is a rotary kiln type ore furnace 10 including the conventional ore preheater 30 shown in FIGS. 1 and 2.

On the lower end of the ore preheater, ie on the rotary kiln kiln ore entrance 31

Exhaust gas discharge duct 35 is made and the cooling jacket-type pipe 60 is first installed to exhaust the high-temperature exhaust gas from the ore preheater 30 to the exhaust gas temperature after the heat exchange sensible heat is recovered.

It is supplied to the water-cooled heat exchanger 70 that can be cooled, through which the exhaust gas is cooled and then discharged to the upper exhaust gas discharge pipe 35 of the ore preheater.

By-pass piping system having such a configuration is designed to have a very low pressure loss compared to the pressure loss of the flue gas passing through the shaft-type ore preheater, so that the by-pass primarily inhaling the flue gas in the rear exhaust gas suction fan 45 The flow of flue gas through the pipe is easy to adjust the flow rate of the high-temperature damper valve (76a) and the slide valve (76b) installed in the front and rear end of the exhaust gas cooling heat exchanger.

The action that can be obtained through the installation of the bypass pipe is basically the fine ore particles generated during the firing process of the ore layer in the shaft-type ore preheater, which shows the one-way suction characteristics of the exhaust gas by the suction fan having a large suction capacity. As the pores are closed in the process of being scattered by a large amount of exhaust gas discharge, the exhaust gas can not be discharged smoothly. This phenomenon can be primarily alleviated.

That is, the driving force through the bypass pipe becomes larger than the driving force passing through the shaft-type ore preheater, and thus, the shaft ore preheater acts to lower the pressure loss of the ore layer overall, thereby improving the breathability of the ore preheater. In addition, the solid particles floating in parallel can be collected and removed through the characteristic of being easily discharged through the by-pass pipe rather than the large prestressed ore preheater, thereby reducing the concentration of suspended fine particles in the furnace body. have.

In addition, the structure of the by-pass pipe exhaust gas cooling heat exchanger according to the present invention adopts a water cooling jackel 70a to have a rapid instant cooling of the exhaust gas, and the rapid temperature drop of the exhaust gas brings about a rapid volume reduction and contains it through a flow rate reduction. Since the rate of scattering of the fine particles is reduced, a large amount of fine particles containing flue gas can be separated and sedimented from the flue gas in the lower settling tank 73 at the lower end of the flue gas heat exchanger 70.

Gravity sedimentation collected particulates have a structural feature so that when a certain amount is collected on the rotary valve 81 bucket can be automatically cut out to be discharged to the lower particulate collection hopper (80).

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings and embodiments.

When the ore preheater By-pass piping system of the present invention is applied to 350 tons of limestone production equipment of A company, the limestone or dolomite is used as a raw material and the rotary kiln is produced using coke oven gas (COG) using limestone or dolomite. Of type lime calcination furnace

The operating conditions are as follows.

2 is a combustion of COG burner used as a heat source in the existing lime-fired furnace

Shows the ore preheater and ore loading and flue-gas flow paths installed to recover sensible heat from the hot combustion flue-gases emitted by the system. Basically, the furnace firing temperature is usually 980 ~ 1100 ℃, and the exhaust gas discharge flow rate of fluid fuel is about 64000Nm3 / hr.

Therefore, a large amount of fine ore is differentiated during the firing process, they are scattered by the flue gas generated in the furnace, and the dust is discharged through the stack after being collected through the ore preheater and the rear flue gas dust collecting facility.

Therefore, in the operation of the rotary kiln type calcination furnace before the improvement, the suction fan strongly suctions the furnace exhaust gas from the rear end of the ore preheater, but after a certain time, the pressure in the furnace at the ore duct part 35 becomes -5 to +2 mmAq. There was a problem that no further negative pressure was formed, and the orbit of the suction fan also had a problem that could not be opened more than 30-40%.

Even if they open more orbits, they found that the outside air is introduced through the bottom of the multi-cylon or the ore supply surgy hopper, and the intake of exhaust gas is not achieved due to the poor breathability of the ore preheater. Therefore, the existing rotary kiln lime kiln has a design limit of 500 tons / day lime kiln, but the operation limit is set to absolutely low fuel unit and combustion air volume. Due to the presence of the high temperature part of the operation problems such as the formation of deposits showed an average of about 280 ~ 350 tons / day was forced to operate. An example of the operating conditions is shown in Table 1.                     

Therefore, to improve the air permeability of the flue gas in the furnace by installing an exhaust gas outlet through the exhaust gas outlet at the lower end of the ore preheater, that is, the preheating ore loading of the rotary kiln type calcination furnace, under the above conditions. It was. As a result, the hot exhaust gas discharged through the exhaust gas bypass pass system installed on the ore entrance duct is about 1/10 volume ratio of the total generated combustion gas, and the exhaust gas bypass heat exchanger has a discharge temperature of about 1000 C. Through this, it was confirmed that the temperature dropped to 280 C, and a large amount of fine dust was collected and discharged through the lower rotary valve.

Bypassing the calcination furnace, the suction fan trajectory is also 80%.

Even if the heat was heated, it could be confirmed that the exhaust gas generated in the furnace was discharged smoothly without the introduction of external air through the cyclone or the ore supply surgy hopper valve.                     

Therefore, it was also confirmed that the furnace pressure was lowered to -10 to -5 mmAq by the suction fan under normal operating conditions. In addition, the fuel source unit was initially increased from 1000 kcal / Kg-CaO to 1150kcal / Kg-CaO to increase product output, and as a result, the suction fan trajectory can be opened up to about 80% more than before improvement, and smooth exhaust gas ventilation is ensured. As a product firing rate index, the hydration rate also improved significantly from 88% to 94% compared to the existing 80%. Table 2 summarizes the operating conditions at this time.

The primary improvement effect through the operation of the present invention was to improve the flame shape to a horizontal shape through the improvement of air permeability of the ore preheater, a large amount of fine ore

By removing the exhaust through the by-pass piping heat exchanger,

It was confirmed that the formation is significantly reduced.                     

The present invention applies a By-pass piping system to improve the air permeability of the ore preheater as a core device of a rotary kiln type ore kiln, and the exhaust gas containing fine particles through the By-Pass pipe heat exchanger together with the smooth discharge of the generated flue gas by the suction fan. Separation and discharge of ores could mitigate the formation of deposits in the furnace.

Claims (3)

In a rotary kiln type ore kiln comprising a rotary kiln, a cooling device, an ore preheater and a kiln ore loading inlet duct, The exhaust gas discharge duct 35 is installed to discharge the exhaust gas from the upper end of the ore preheater, and a cooling jacket type pipe 60 is installed at one side of the kiln ore entrance inlet duct, and the ore preheater 30 is heated at a high temperature. Rotary kiln type ore kiln, characterized in that the water-cooled heat exchanger 70 is installed to cool down to the exhaust gas temperature discharged after the heat exchanging heat from the heat recovery. The method of claim 1, A pipe connected to a rear end of the ore preheater exhaust gas discharge pipe 35 has an exhaust gas opening and closing valve 76, and cooling water pipes 67, 66, 68, and 65 for bypass exhaust gas cooling are provided at the front and rear ends of the heat exchanger 70. Rotary kiln type ore furnace, characterized in that connected. The method of claim 1, The rotary kiln type ore-calcining furnace preheats and charges the charged ore using exhaust gas Bottom of ore preheater in rotary kiln ore kiln with shaft type ore preheater By installing an exhaust gas discharge line at the kiln inlet and separating and discharging a large amount of less than -1mm of fine powder contained in the flue gas discharged through the exhaust gas discharge line from the water cooling heat exchanger Improving the breathability of the ore preheater and suppressing the formation of deposits in the rotary kiln furnace. Features of Rotary kiln ore kiln.

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