KR102313703B1 - Extraction Equipment For Circulation Material in Combustion Gas of Alternative Fuel and in Decomposition Gas of Raw Meal in Cement Plant - Google Patents

Abstract

The present invention relates to a facility and a process, which extracts, together with kiln flue-gas, a part of a circulating material adversely affects a calcination process from high-temperature combustion gas and raw material cracking gas resulting from use of a waste synthetic resin as an alternative fuel for coal in a cement kiln. According to the present invention, an extraction apparatus for extracting kiln exhaust gas discharged from a kiln of a cement manufacturing facility comprises: a fire-resistant structure installed on the wall of a cement firing chamber to form an exhaust gas outlet; an outer cylinder mounted on the fire-resistant structure and having a cooling air inlet for distributing cooling air formed at one end to guide the cooling air to the exhaust gas outlet; a hollow inner cylinder installed in the center of the outer cylinder, having one end facing the exhaust gas outlet, and having the other end extending to the outside through the outer cylinder to extract the exhaust gas from the exhaust gas outlet; and a plurality of rotation guide plates installed a space, which is as a downward flow path of the cooling air introduced into the cooling air inlet, between the outer cylinder and the inner cylinder to guide the rotational flow of the introduced cooling air. The rotation guide plate has a predetermined angle while extending toward the exhaust gas outlet.

Description

Extraction Equipment For Circulation Material in Combustion Gas of Alternative Fuel and in Decomposition Gas of Raw Meal in Cement Plant

The present invention relates to a facility and process for withdrawing a part of the circulating material adversely affecting the calcination process among high-temperature combustion gas and raw material cracking gas resulting from the use of waste synthetic resin as an alternative fuel for coal in a cement kiln together with the kiln flue-gas.

Cement factories use a variety of combustible recycled recycling fuels by substituting coal as a heat source for manufacturing cement. is of great help to

The components such as chlorine compounds, alkali compounds, and sulfur compounds contained in cement raw materials and fuels are volatilized and decomposed at a high temperature of 1000~1450℃ or higher inside the cement kiln. It is essential to remove them because they are condensed on raw materials as low as 900°C and have a huge impact on operation by obstructing the flow of raw materials due to their high tackiness.

In particular, the high-concentration chlorine compound contained in the waste synthetic resin is a substance that impedes the flow of raw materials and must be withdrawn because it is in a gaseous state in the kiln exhaust gas at a high temperature of 1050 to 1150°C. From cubic meters (m ³ ) to more than a thousand cubic meters ( m ³ ), a large amount of cement raw materials are discharged together with it.

The temperature of the withdrawal gas from the exhaust gas of the cement kiln is about 1050~1150℃, and the chlorine compound contained in this exhaust gas is rapidly cooled to 450℃ or less so that the gaseous state becomes a solid state. is forcibly introduced. When the withdrawal amount of the exhaust gas from the kiln is small, there is no problem because the facility is small and the amount of cooling air flowing in is small. The amount of dust that is withdrawn and the equipment that needs to be collected will also increase.

When the cooling air flows into the kiln, the gas and raw material temperatures drop abruptly in that part, and the fine raw materials and circulating materials condense and adhere to each other on the kiln wall. The shape of the hot gas inlet part of the draw-out facility is very important because it greatly hinders the cooling air from the draw-out facility.

1A and 1B are cross-sectional views schematically illustrating the structure of a conventional withdrawal device.

Referring to FIG. 1 , the withdrawal device is installed on the wall of the inlet chamber of the kiln so that high-temperature exhaust gas can be withdrawn through the outlet 20 of FIG. 1A . The withdrawing device is largely composed of an outer cylinder 30 and an inner cylinder 50, and the cooling air flowing in through the cooling air inlet 18 of the outer cylinder passes through the cooling air flow path between the outer cylinder 30 and the inner cylinder 50 and is below. direction, passes through the cooling air discharge unit 18 (a), and is extracted together with the exhaust gas from the end 19 of the inner cylinder.

There are two major problems when withdrawing exhaust gas from the kiln inlet chamber 15, one of which is when a large amount of exhaust gas is withdrawn from the kiln inlet chamber 15, that is, the volume of exhaust gas of the kiln When withdrawing more than 5% by fraction, a lot of cooling air is required, and when the strength of the cooling air flow increases and the cooling air flows into the kiln inlet chamber 15, as shown in FIG. 1B, alkali with high temperature adhesiveness Raw materials containing a lot of compounds, chlorine compounds, and sulfur compounds are attached (22a, 22b) and must be removed.

In addition, when the strength of the cooling air flow is large and flows into the kiln inlet chamber 15, the high-temperature gas is cooled and the efficiency of heat exchange in the preheating chamber 8 is lowered, so that more fuel is supplied to the sintering process, resulting in energy loss. This phenomenon interferes with the stable operation of the cement kiln and causes a decrease in productivity.

The bold black arrow in FIG. 1B indicates that the cooling air leaks into the kiln inlet chamber 15 through the exhaust gas outlet 20 when the cooling air flow rate is rapidly introduced into the withdrawal device.

Another problem is that in Korea, waste synthetic resin used as an alternative fuel for coal in the cement firing process controls the quality such as calorific value, chlorine content, size, moisture content, and foreign matter content. When the ratio is as high as 56.8%, a polyvinyl chloride-based plastic is sometimes mixed, and a polyvinylidene chloride-based synthetic resin with a chlorine content higher than vinyl chloride at 73.1% by weight is mixed. Therefore, the chlorine content of the used synthetic resin is high, and the chlorine content dispersion is also greatly increasing.

In particular, when the chlorine content of the waste synthetic resin is high, even if a large amount of exhaust gas is withdrawn from the withdrawal device, the chlorine content in the cement product increases and exceeds the regulation value. Close the damper and open the outlet duct damper of the withdrawal device to increase the amount of extraction gas and dust to keep the chlorine content within the regulated value.

(1) KR 2001-0079060 A (2) KR 2014-0112520 A (3) KR 2000-0068565 A

In order to solve the problems of the prior art, an object of the present invention is to provide a withdrawal device for suppressing the condensation of the adhesive compound at the exhaust gas outlet of a cement kiln.

Another object of the present invention is to provide an exhaust gas extraction device suitable for use of combustible recycled circulating fuels such as chlorine compounds and sulfur compounds in a cement kiln.

In order to achieve the above technical object, the present invention provides an extraction device for extracting kiln exhaust gas discharged from a kiln of a cement manufacturing facility, comprising: a fireproof structure installed on a wall of a cement firing chamber to form an exhaust gas outlet; an outer cylinder mounted on the fire resistant structure and provided with an inlet for cooling air at one end to guide the cooling air to the exhaust gas outlet; A hollow inner cylinder installed in the middle of the outer cylinder, one end facing the exhaust gas outlet, and the other end extending through the outer cylinder to the outside in order to withdraw exhaust gas from the exhaust gas outlet; and inflow into the cooling air inlet It provides a kiln exhaust gas extraction device, characterized in that it includes a rotation guide plate for guiding the rotation of the incoming cooling air installed between the outer cylinder and the inner cylinder, which is a flow path in the downward direction of the cooling air.

In the present invention, the rotation guide plate may have an angle of preferably 0 to 60 degrees, 5 to 60 degrees or 15 to 60 degrees with respect to the central axis of the hollow inner cylinder.

In the present invention, the exhaust gas outlet formed by the fire resistant structure may further include a cooling air induction unit protruding toward the inner cylinder to form a cooling air discharge unit between the exhaust gas outlet and the inner cylinder.

In the present invention, the cooling air induction unit may form an acute angle with the exhaust gas outlet.

The present invention enables stable operation of the cement kiln by improving the performance of efficiently removing chlorine compounds, etc. that interfere with the cement manufacturing process during operation, from the extraction device in utilizing the calorific value of the waste synthetic resin, thereby increasing productivity. As a result, energy is saved and cement quality is improved, which ultimately reduces the cement manufacturing cost. In addition, the use of waste synthetic resin can be increased, so that the coal replacement rate can be increased, and also the amount of greenhouse gas reduction can be improved more effectively.

1 is a view schematically showing a withdrawal device for withdrawing hot gas in a conventional cement production facility.
2 is a conceptual diagram for explaining a treatment process of withdrawing the exhaust gas of the cement kiln.
3 is a cross-sectional view schematically illustrating an exhaust gas extraction device according to an embodiment of the present invention.
4A and 4B are a plan view and a side view schematically showing an exhaust gas extraction device of the present invention, respectively.
5 is a cross-sectional view schematically showing an exhaust gas extraction device according to another embodiment of the present invention.
6 to 9 are views showing simulation results for the structure of the withdrawal device according to the present invention.

2 is a conceptual diagram for explaining a treatment process of withdrawing the exhaust gas of the cement kiln.

Referring to FIG. 2 , when the finely pulverized cement raw material is supplied to the raw material inlet 14, heat exchange is conducted at about 800 to 900° C. while passing through the preheating chamber 8, and finally the kiln 5 through the cement raw material conduit 8a. ) and heated to 1450°C or higher, it becomes clinker, a semi-finished cement product, and is cooled to about 100-200°C in the cooler 6, which is then finely pulverized to make cement products.

The combustion furnace 13 for burning the cement fuel of FIG. 2 has a function of increasing the residence time of the fuel particles and the combustion gas to about 6 to 10 seconds and the combustion temperature to about 900° C. so that the waste synthetic resin can be completely burned. .

Since the waste synthetic resin contains components that adversely affect the cement process, such as chlorine, sulfur, and alkali, among them, especially chlorine components, when introduced into the cement kiln 5, volatilize from about 1000 ° C. It is condensed on the cement raw material at 800~900℃ in 8b) and the adhesion is increased and the smooth flow of the raw material is blocked and the operation of the cement manufacturing process must be stopped. In order to prevent this in advance, the high-temperature gas is withdrawn by the extraction device 1 for withdrawing the chlorine component contained in the waste synthetic resin and the alkali component of the raw material. Cooling air is forcibly introduced into the kiln exhaust gas at about 1050 to 1150° C. drawn into the withdrawal device 100 through the cooling fan 2 to cool it to 450° C. or less, and is cooled by the secondary cooling air inlet pipe 17b. After additional air is introduced to finally make the temperature below 200°C, dust is collected in the bag filter 4 and the gas is discharged.

The high-temperature gas of 1050 to 1150° C. withdrawn from the extraction device 100 of FIG. 2 is contained together with dust containing chlorine compounds, sulfur compounds, alkali compounds, and the like. In particular, the flow of the raw material in the raw material conduit 8a is improved only when the chlorine compound is drawn out of these, so that the kiln can be operated stably. Chlorine compounds are discharged to the exhaust gas of the kiln. Since chlorine compounds are attached to the gaseous state and the dust surface, they are taken out and cooled to 450℃ or less in a short time to attach to gaseous chlorine compounds and dust in a liquid state. It is necessary to make the chlorine compound in a solid state and withdraw it to the outlet 19 of the withdrawal device.

Representative chlorine compounds that adversely affect the stable operation of the cement firing process are potassium chloride (KCl) and calcium chloride (CaCl ₂ ), whose melting temperatures are 770 ° C and 772 to 775 ° C, respectively. It does not become completely solid in a short period of time taken out, but becomes a semi-solid state with adhesiveness, and as shown in FIG. Therefore, when it is necessary to withdraw a large amount of high-temperature gas from the kiln inlet chamber 15 , the high-temperature gas must be cooled quickly and dust adhesion to the kiln inlet chamber 15 must be suppressed as much as possible.

3 is a cross-sectional view schematically illustrating an exhaust gas extraction device according to an embodiment of the present invention.

Referring to FIG. 3 , the withdrawal device 100 may be installed on the wall of the entrance 15 of the firing chamber, and largely includes an outer cylinder 130 and an inner cylinder 150 . The fire resistant structure 110 on the wall of the inlet 15 of the firing chamber supports the extraction device 100 , and an exhaust gas outlet 120 is formed therein.

The outer cylinder 132 of the extraction device 100 has a cooling air inlet 132 for distributing cooling air at one end, and the exhaust gas outlet 120 through the cooling air flow path between the outer cylinder and the inner cylinder. ) to lead to

On the other hand, the inner cylinder 150 has a hollow structure and is installed in the center of the outer cylinder, one end faces the exhaust gas outlet 120 , and the exhaust gas outlet 152 is the outer cylinder to draw exhaust gas from the exhaust gas outlet. through and extending to the outside.

On the other hand, the withdrawal device 100 includes a plurality of rotation guide plates 170 installed between the outer cylinder and the inner cylinder, which is a downward flow path of the cooling air introduced into the cooling air inlet, and the rotation guide plate 170 is Guide the incoming cooling air to rotate. Accordingly, the high temperature exhaust gas and cooling air in the inner cylinder 150 of the take-out device 100 increase the residence time, thereby increasing heat exchange between the cooling air and the exhaust gas and improving the cooling efficiency. Also, by increasing the lateral component of the cooling air flow, it is possible to suppress the cooling air from flowing out to the exhaust gas outlet.

In the present invention, the rotation guide plate 170 extends from the top to the bottom at a predetermined angle toward the outlet of the flow path of the cooling air. In the present invention, the angle between the rotation guide plate 170 and the inner cylinder central axis is preferably 0 to 60 degrees, 5 to 60 degrees, or 15 to 60 degrees.

4A is a plan view of the take-out device of FIG. 3 viewed from above after cutting it along the line A-A', and FIG. 4B is a schematic side view of the take-out device.

As shown, four rotation guide plates 170 are provided between the outer cylinder and the inner cylinder of the withdrawal device 100 . In addition, the rotation guide plate 170 is formed along the outer cylinder surface, the rotation guide plate 170 is inclined from the top to the downward direction. The rotation guide plate 170 may be arranged at periodic or irregular intervals along the circumference of the outer cylinder, and the angle formed with the central axis of the inner cylinder is preferably in the range of 0 to 60 degrees, 5 to 60 degrees or 15 to 60 degrees. It may have an arbitrary angle, and the inclination angles of the individual rotation guide plates 170 may be different from each other.

Again, referring to FIG. 3 , the take-off device 100 of the present invention may further include a cooling air induction unit 180A. The cooling air induction part 180A protrudes toward the inner cylinder from the exhaust gas outlet formed by the fire resistant structure. Accordingly, the cooling air discharge portion 154 formed between the exhaust gas outlet and the inner passage moves away from the exhaust gas outlet. Accordingly, when a large amount of high-temperature gas is withdrawn from the kiln inlet chamber 15, dust adhesion to the kiln inlet chamber 15 is maximally suppressed even when a large amount of cooling air is circulated to the blower 2 in order to rapidly cool it. can make In the present invention, the cooling air induction part may be made of a heat-resistant material so as not to be corroded and deteriorated by the high-temperature gas of the kiln exhaust gas.

5 is a cross-sectional view schematically showing an exhaust gas extraction device according to another embodiment of the present invention.

Referring to FIG. 5 , the illustrated extractor is the same as the extractor of FIG. 3 , except that the cooling air induction unit 180B is inclined to have an acute angle with respect to the exhaust gas outlet 120 . In the present invention, the inclination angle may be in the range of 15 to 75 degrees. The cooling air induction part 180A of FIG. 3 has the advantage of being easy to manufacture, although the pressure loss is as high as 113 mmAq in several weeks because the cooling air is turned twice at a 90° angle, and the cooling air induction part 180B of FIG. 5 is cooled Since the air is gently discharged from the outlet, the pressure loss is less than 41mmAq for several weeks, but it is difficult to manufacture.

The pressure loss βP generated in the cooling air induction units 180A and 180B can be calculated by the following formula. The coefficient of friction used in the calculation formula can be used in general pipelines.

(Pressure loss calculation formula)

ΔP =4 * f * L * ρ * V ² / (2 * g * D) (here, f: friction coefficient, L: pipe length, D: pipe diameter, ρ: air density, V: air velocity, g: gravitational acceleration

f ≒ 1 (when turning 90°)

≒ 0.022 to 0.785 (when turning at an angle of 15 to 75°)

6 shows computational fluid dynamics in order to determine the extent to which cooling air flows from the exhaust gas outlet 120 into the kiln inlet chamber 15 when cooling air is introduced into the cooling air inlet 132 of the withdrawal device. As a figure showing the results of the simulation experiment with the program (STAR CCM+), this simulation was performed without the cooling air rotation guide plate 170 .

Referring to FIG. 6 , when the cooling air rotation guide plate 170 is not installed, cooling air partially escapes from the exhaust gas outlet 120 of the extractor and flows into the kiln inlet chamber 15 (black solid line) part), it can be seen that there is a possibility that a coating may occur as shown in FIG. 1B . In FIG. 8, the standard deviation of the gas temperature and the gas temperature at the outlet 152 of the extraction device is shown in Table 1.

at the exit of the withdrawal device
Gas temperature (℃) of gas temperature
Standard Deviation number of data note 398 237.7 772 º Cooling air induction part: None
º Rotation guide plate: None

7 is a simulation result of four rotation guide plates 170 installed at regular intervals at predetermined angles within the range of 30° to 90° for cooling air rotation between the inner cylinder 150 and the outer cylinder 130 of the take-off device. It is a picture that represents

Referring to FIG. 7 , it can be seen that the hot gas and the cooling air are uniformly mixed in the extraction device 100 compared to the case in which the cooling air rotation guide plate 170 is not installed ( FIG. 6 ), and the exhaust outlet of the extraction device 100 From (152), it can be seen that the discharge temperature is decreasing. In addition, although it is shown that the cooling air does not flow into the kiln inlet chamber 15, it can be seen that a small amount of cooling air flows out immediately after the exhaust gas outlet 120 of the extractor 100. In this case, the kiln Coating does not occur in the inlet chamber 15, but coating occurs in the exhaust gas outlet 120, making it difficult to smoothly take out the hot gas. The performance of the take-out device at this time is shown in Table 2, and it has been shown that it is better than that of FIG. 6 .

at the exit of the withdrawal device
Gas temperature (℃) of gas temperature
Standard Deviation number of data note 358℃ 176.4 772 º Cooling air induction part: None
º Rotation guide plate: Yes

8 is a cooling air rotation guide plate 170 installed as shown in FIG. 7 between the inner cylinder 150 and the outer cylinder 130 of the withdrawal device, and a cooling air induction part 180A in a vertical form to the exhaust gas outlet 120 is installed. The figure shows the simulation result in the formed state.

8, when the vertical cooling air induction unit 180A is installed, the cooling air discharged from the exhaust gas outlet 120 and the high-temperature gas are mixed and the temperature is lowered at the outlet 152 of the extractor, and the kiln inlet chamber In (15), it was confirmed that the cooling air did not flow, and the cooling air did not flow out immediately after the exhaust gas outlet 120 . Due to the installation of the vertical cooling air induction part, the hot gas in the inner cylinder 150 of the withdrawal device is not biased and is mixed well with the cooling air. The withdrawal device performance is shown in Table 3 below.

at the exit of the withdrawal device
Gas temperature (℃) of gas temperature
Standard Deviation number of data note 342 10.6 772 º Vertical induction part: Yes
º Rotation guide plate: Yes

9 is a state in which the cooling air rotation guide plate 170 is installed between the inner cylinder 150 and the outer cylinder 130 of the extraction device, and a cooling air induction part 180B having an inclination is formed in the exhaust gas outlet 120. The figure shows the simulation result.

When the inclined cooling air induction part 180B is installed in the exhaust gas outlet 120, a uniform mixing of the hot gas and the cooling air is sufficiently performed compared to the vertical cooling air induction part 180A, so that the temperature at the outlet 152 of the extraction device is lowered. It can be seen that the cooling air does not flow out even immediately after the exhaust gas outlet 120 , and the cooling air does not flow into the kiln inlet chamber 15 . The performance of the withdrawal device is shown in Table 4.

at the exit of the withdrawal device
Gas temperature (℃) of gas temperature
Standard Deviation number of data note 306℃ 7.6 772 º Inclined induction part: Yes
º Rotation guide plate: Yes

100: withdrawal device
2: blower
3: Cyclone
3a : cyclone exit damper
4. : Bag filter
5: Rotary kiln
6: cooler
7a: tertiary air supply pipe
7a: tertiary air connection
8 : 5-stage preheating room
8a: raw material conduit at the bottom of the preheating room
8b: Preheating room 2nd stage raw material conduit
9: Preheating room forced suction fan
10: bag filter forced suction fan
11: synthetic resin input device
12: cooler dust collector
13: combustion furnace
14: cement raw material input port
15: kiln inlet chamber
15A: kiln entrance room wall
16: withdrawal gas connection pipe
17: bag filter connector
17a: take-off device exit damper
17b: secondary cooling air inlet pipe
18: intake device cooling air inlet
18a: cooling air discharge part
19: exhaust gas outlet
20: exhaust gas outlet
21: once inner pain
22a, 22b: Cement raw material coating
110: fire resistant structure
120: exhaust gas outlet
130: outer cylinder
132: cooling air inlet
150: inner tube
152: exhaust gas outlet
154: cooling air discharge unit
170: cooling air rotation guide plate
180A, 180B: Cooling air induction part

Claims (4)

In the extraction device for extracting the kiln exhaust gas discharged from the kiln of a cement manufacturing facility,
a fire resistant structure installed on the wall of the cement firing chamber to form an exhaust gas outlet;
an outer cylinder mounted on the fire resistant structure and provided with a cooling air inlet for distributing cooling air at one end to guide the cooling air to the exhaust gas outlet;
a hollow inner cylinder installed in the middle of the outer cylinder, one end facing the exhaust gas outlet, and the other end extending through the outer cylinder to the outside in order to extract exhaust gas from the exhaust gas outlet; and
and a plurality of rotation guide plates installed between the outer cylinder and the inner cylinder, which are flow paths in the downward direction of the cooling air introduced into the cooling air inlet, to change the flow direction of the incoming cooling air,
The rotation guide plate extends toward the exhaust gas outlet and has a predetermined angle. According to claim 1,
The rotation guide plate is a kiln exhaust gas extraction device, characterized in that it has an angle of 0 to 60 degrees with respect to the central axis of the hollow inner cylinder. According to claim 1,
The kiln exhaust gas extraction, characterized in that it further comprises a cooling air induction part protruding toward the inner cylinder from the exhaust gas outlet formed by the fire resistant structure to form a cooling air discharge part between the exhaust gas outlet and the inner cylinder. Device. 4. The method of claim 3,
The kiln exhaust gas extraction device, characterized in that the cooling air induction portion forms an acute angle with the exhaust gas outlet.

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