KR20080113703A

KR20080113703A - Coal drying system using flue gas as inerting agent

Info

Publication number: KR20080113703A
Application number: KR1020070062500A
Authority: KR
Inventors: 최태영
Original assignee: 최태영
Priority date: 2007-06-25
Filing date: 2007-06-25
Publication date: 2008-12-31
Also published as: KR100927875B1

Abstract

Coal drying system using the exhaust gas as a sealing material according to the present invention, the boiler (5) for generating steam by burning coal; A coal storage tank 2 storing coal; A coal feeder (3) for transferring coal of the coal storage tank (2) by the required amount in the boiler (5); A pulverizer (4) for crushing the coal received from the feeder (3) into a fine powder state, drying and supplying the coal to the boiler (5); Combustion gas discharge pipe (6) for discharging the combustion gas from the boiler (5); An air inlet pipe (7) for injecting external air necessary for burning fuel in the boiler (5); An air preheater (8) for preheating the outside air in the air inlet pipe (7) by heat exchange between the combustion gas discharge pipe (6) and the air inlet pipe (7); A preheated air delivery pipe (12) for branching preheated external air in the air inlet pipe (7) and supplying it to the mill (4); A first dust collecting device (9) connected to the combustion gas discharge pipe (6) to collect contaminants and dust in the combustion gas; And a combustion gas discharge path 60 for branching a part of the combustion gas discharged from the boiler 5 and supplying the coal gas to the coal storage tank 2. The combustion gas introduced into the coal storage tank 2 includes the coal; The wet coal in the reservoir 2 is dried. The present invention uses the exhaust gas that prevents combustion or explosion due to low oxygen concentration from the coal combustion facility as a sealing material, so that the exhaust gas, steam, or hot water is dried by drying the coal with a heat source, so that there is no danger of coal explosion accident. It can safely reduce the moisture in the coal, and has the advantage of promoting the effective use of fuel resources by enabling more active use of low-cost coal, which is high in moisture and low in calories.

Description

Coal drying system using flue gas as inerting agent

1 is a block diagram illustrating a coal supply system of a conventional coal-fired boiler.

2 is a schematic diagram of a coal drying apparatus using steam as a heat source in a conventional coal combustion system.

3 is a configuration diagram of a coal drying system using exhaust gas as a sealing material according to a first embodiment of the present invention.

Figure 4 shows a configuration for controlling the flow rate of the combustion gas injected into the coal storage tank 2 according to the temperature of the combustion gas discharged from the coal storage tank 2 in the coal drying system according to the present invention.

5 is a configuration diagram of a coal drying system using exhaust gas as a sealing material according to a second embodiment of the present invention.

6 is a configuration diagram of a coal drying system using exhaust gas as a sealing material according to a third embodiment of the present invention.

7 is a configuration diagram of a coal drying system using exhaust gas as a sealing material according to a fourth embodiment of the present invention.

8 is a detailed configuration diagram of the coal drying unit 200 shown in FIG.

* Description of the symbols for the main parts of the drawings *

1 ': Coal supply and combustion system of existing boiler

1,1a, 1b, 1c, 1d: coal drying system

2: coal storage tank 2a: coal supply hopper

2b: coal input door 2c: coal discharge door

3: feeder 4: differential

5: boiler 5a: steam generating tube

5b: coal inlet 5c: air inlet

6: flue gas discharge pipe 6a: flue gas branch point

6b, 6c: combustion gas pipe 7: air inlet pipe

7a: Preheating air junction 8: Air preheater

9: first dust collector 10: stack

10a: exhaust gas 11a: primary air blower

11b: press blower 11c: manned blower

11d: combustion gas blower

11e: exhaust fan 12: preheating air delivery piping

19: second dust collector 20: coal dryer

20a: Hopper 20b: Hopper Outlet

21: rotating drum 22: support

23: driven part 24: drive motor

25: dry coal hopper 26: conveyor

27: steam and hot water pipe 40: coal supply pipe

60: combustion gas delivery path 60a: combustion gas branch point

60b: combustion gas confluence point 61: first damper

62: combustion gas supply unit 63: second damper

64: temperature sensor 65: combustion gas outlet

67: heat pipe 67a: combustion gas exhaust pipe

68: combustion gas branch point 69: combustion gas supply pipe

70: coal dust collector 71: gas discharge pipe

72: combustion gas delivery pipe 73: coal dust delivery passage

77: coal dust 200: coal drying unit

210: coal dryer 212: aeration belt

213: Vent belt pulley 214: Adjustable roller

215: rocking roller 217: coal leakage

218: rotary valve C: coal

D: dried coal

The present invention relates to a coal drying system using exhaust gas as a sealing material. In particular, by drying coal with exhaust gas from a coal combustion boiler, coal is dried at low cost without loss of energy to increase combustion efficiency and at the same time, The present invention relates to a coal drying system that prevents danger and safely and effectively removes moisture from coal.

Conventionally, in large-scale workplaces that require a large amount of thermal energy, such as thermal power plants and steel mills in Korea, coal is mainly used as fuel. Coal is the lowest cost and most abundant reserve in fossil fuels, but it is a stable fuel supply. However, the complex for combustion is complicated and causes various problems in the process of transmitting combustion and heat. Has the disadvantage of being complicated.

1 is a block diagram illustrating a coal supply system of a conventional coal-fired boiler, a boiler and a system for supplying coal to the boiler and a system for treating exhaust gas of the boiler, which are the most common equipment for burning coal and converting it into thermal energy. Is shown. Referring to Figure 1, the coal supply and combustion system of the existing boiler (1 '), the coal storage tank (2) for storing the coal to be used as fuel, the coal of the coal storage tank (2) is supplied to the boiler (5) A coal feeder 3, a coal mill 4 to pulverize the coal received from the coal feeder 3 to form a fine powder, and dry it, and receives and combusts the fine powder coal of the mill 4; Boiler 5 to generate a heat, the combustion gas discharge pipe 6 for discharging the combustion gas from the boiler 5 to the outside, the combustion gas discharge pipe 6 and the air inlet pipe (7) by heat exchange It consists of an air preheater 8 for preheating the external air introduced into the dust collector, and a dust collector 9 for collecting dust in the combustion gas.

When coal is transported to the conveyor from the outside and supplied to the upper portion of the coal storage tank (2), the feeder (3) adjusts the supply amount of coal for controlling the heat load of the boiler (5) and sends it to the mill (4).

The pulverizer 4 is a facility having a function of pulverizing and drying coal, the coal pulverized in the pulverizer 4 is heated by the air preheater 8 and by a primary air fan 11a. While being dried by the pressurized air, only coal having a small particle loaded in the air stream is sent to the combustion device of the boiler 5 to be burned. Exhaust flue gas from the boiler 5 is used to heat the external incoming air of the air inlet pipe 7 by heat exchange in the air preheater 8, and then removes dust and the like from the dust collector 9, Through the chimney, 10) into the atmosphere.

In FIG. 1, reference numeral 5b is a coal supply port of the boiler 5 to which a coal supply pipe 40 is connected, and 5c is an air inlet port through which external air enters. And reference numeral 11a is a primary air blower that sends the preheated air to the differentiator (4) through the preheating air delivery pipe 12, 11b is a press-fit blower for blowing outside air into the air inlet pipe (7), 11c is a dust collector It is a manned blower which discharges the combustion gas which passed through the apparatus 9 to the stack 10. Reference numeral 10a denotes the exhaust gas exiting the stack 10.

As shown in FIG. 1, in a plant that burns using coal, when moisture is high in coal, coal becomes more cohesive and adheres to the wall of the coal storage tank 2, and coal is further attached on the coal attached to the coal storage tank. (2) is blocked and the supply of coal is stopped. This phenomenon also occurs in the coal supply pipe 40 that passed the feeder 3. The pulverizer 4 has a function of pulverizing coal in a particulate state so as to easily burn it, and at the same time, drying the moisture in the coal by preheated air (primary air). Referring to FIG. 1, since the moisture coal supplied to the fine powder 4 is difficult to dry, the flow rate of the primary air in the preheating air delivery pipe 12 must be supplied a lot, and the temperature is also high to allow drying. If the temperature of the primary air is above 240 ° C, there is a possibility of explosion inside the mill 4 due to the volatile matter present in the coal, so it is impossible to raise the temperature of the primary air to above 240 ° C. .

In addition, if the coal pulverized in the mill 4 is not sufficiently dried, the weight of the coal particles is not reduced and is carried by the air stream of the primary air so that it cannot be supplied into the boiler 5 and recycled back to the mill 4. do. In addition, since the flow rate of the primary air flowing through the preheating air delivery pipe 12 is limited, the water in the coal eventually reduces the grinding capacity of the mill 4 and cannot supply enough pulverized coal to produce steam in the boiler 4. Will be reduced.

If the pulverized coal supply at the outlet of the pulverizer 4 is forcibly increased despite this phenomenon, the coal supply pipe 40 is blocked and the supply of primary air and pulverized coal is reduced, and the flame of the boiler 5 is reversed. To reverse the overheating of the coal supply pipe (40) or severely causes an explosion in the coal supply pipe (40) to cause a serious equipment destruction.

As described above, in most coal combustion facilities as shown in FIG. 1, if there is a large amount of coal in the coal storage 2, the coal grinding capacity of the fine powder 4 is lowered, and the coal supply pipe 40 of the fine powder 4 is reduced. ) Is not only difficult to control the combustion device's output, but also can cause explosion or fire. In addition, the moisture present in the coal is discharged in a state of high steam in the amount of heat when the coal is burned to exhaust the exhaust gas, it takes out the heat generated by the combustion as it is causing the exhaust gas loss.

As mentioned above, the moisture in the coal causes various obstacles in the combustion system and at the same time causes heat loss. In particular, the coal is produced according to the production site, the supply time, and the storage process. There is a problem that even the design and operation of the pre-operation that removes moisture before combustion is not easy because there is a characteristic that the moisture is not constant.

In general, the price of coal purchased for use in a coal-fired plant business varies according to the calorie and moisture content of the coal. When designing a combustion plant, the standard of coal used in the plant and the criteria for moisture and calorific value are determined. Design Coal ("Design Coal") and the range of coal available in the combustion plant ("Range Coal"). The moisture in the coal is composed of adhered moisture adhering to the surface of the coal particles and crystalline moisture present in the crystalline form of the coal particles. Removed.

FIG. 2 is a schematic diagram of a coal drying apparatus 20 using steam as a heat source, which is used in the conventional coal supply and combustion system 1 'of FIG. The rotary coal drying apparatus 20 shown in FIG. 2 solves the problem of calorie loss due to moisture in coal to some extent by drying the steam as a heat source before inputting coal to the boiler 5.

Referring to FIG. 2, the rotary coal drying apparatus 20 using steam as a heat source is provided with a steam tube (not shown) inside an elongated cylindrical rotating drum 21 which is inclined and rotates, When the coal is supplied from the coal supply hopper 2a connected to the inclined upper portion, the coal is heated and dried in contact with the steam tube to gradually descend to the bottom of the rotating drum 21. The steam generated as the coal is dried in the rotary drum 21 is discharged as hot air to be discharged through a dust collector (not shown).

In FIG. 2, the steam passing through the steam tube in the rotary drum 21 is recovered or discharged to the outside, and the coal dried via the rotary drum 21 passes through the dry coal hopper 25 by the conveyor 26. It is transferred to the feeder. In FIG. 2, reference numeral 22 denotes a support for supporting the rotating drum 21, 23 denotes a driven part of the rotating drum 21, and 24 denotes a driving motor 24 for rotating the rotating drum 21.

Since the coal drying apparatus 20 of FIG. 2 uses steam as a heat source, maintenance costs are high, and it is possible to use anthracite coal or a low-volume iron bitumen, but in the case of coal containing a large amount of volatile matter such as sub-bituminous coal. In the process, there is a problem of spontaneous ignition by volatile matter, which makes it difficult to use. In addition, the conventional coal drying apparatus 20 of FIG. 2 has disadvantages in that a complex facility and a large number of failure factors require a lot of manufacturing cost and maintenance cost, and a large site for installing the device.

As mentioned above, the drying method by heat, which is the simplest method of removing water from volatile and watery and inexpensive bituminous coal or sub-bituminous coal, could not be applied due to the flammability of coal and the risk of explosion. As of now, there is no special technology or device that can dry coal at low cost without the risk of explosion and fire. Some of the adhered moisture was evaporated or drained naturally to reduce moisture. If there is more moisture than the contract condition of coal purchase, the coal is purchased in a form of reducing the amount corresponding to the contract excess amount of water from the price of coal, thereby controlling the coal supplier to supply the moisture of the coal lower so that the loss due to moisture in the coal is reduced. Preserved.

In order to solve the above problems, the present invention safely dry the coal with low oxygen concentration combustion gas coming out of the coal combustion equipment or use coal as a sealant to heat and dry the coal so that the moisture in the coal is safely avoided. It reduces the cost of coal purchase by reducing the problems caused by water in coal, reducing the problems caused by water in the coal, and making effective use of fuel resources. It is an object of the present invention to provide a coal drying system using exhaust gas as a sealing material.

In addition, the present invention is to reduce the temperature of the exhaust gas discharged to the atmosphere as possible by recovering and using the exhaust gas from the coal combustion plant to dry the coal as a result, the exhaust gas that can raise the efficiency of the coal combustion plant to the maximum It is an object to provide a coal drying system used as a sealant.

Coal drying system using the exhaust gas provided by the present invention as a sealing material to achieve the above object, the boiler (5) for generating steam by burning coal; A coal storage tank 2 storing coal; A coal feeder (3) for transporting coal in the coal storage tank 2 by the required amount in the boiler 5; A pulverizer 4 for pulverizing the coal received from the feeder 3 into fine powder and feeding it to the boiler 5; Combustion gas discharge pipe (6) for discharging the combustion gas from the boiler (5); An air inlet pipe 7 for introducing external air into the boiler 5; An air preheater (8) for preheating external air in the air inlet pipe (7) by heat exchange between the combustion gas discharge pipe (6) and the air inlet pipe (7); A preheated air delivery pipe (12) for branching preheated external air in the air inlet pipe (7) and supplying it to the mill (4); A first dust collecting device (9) connected to the combustion gas discharge pipe (6) to collect contaminants and dust in the combustion gas; And a combustion gas discharge path 60 for branching a part of the combustion gas discharged from the boiler 5 and supplying the coal gas to the coal storage tank 2. The combustion gas introduced into the coal storage tank 2 includes the coal; It is characterized by drying the wet coal in the reservoir 2.

In addition, the coal drying system using the exhaust gas provided by the present invention as a sealing material in order to achieve the above object, the boiler (5) for generating steam by burning coal; A coal storage tank 2 storing coal; A coal feeder (3) for transferring coal of the coal storage tank (2) by the required amount in the boiler (5); A pulverizer (4) for pulverizing the coal received from the feeder (3) into a fine powder state and supplying it to the boiler (5); Combustion gas discharge pipe (6) for discharging the combustion gas from the boiler (5); An air inlet pipe 7 for introducing external air into the boiler 5; An air preheater (8) for preheating the outside air in the air inlet pipe (7) by heat exchange between the combustion gas discharge pipe (6) and the air inlet pipe (7); A preheated air delivery pipe (12) for branching preheated external air in the air inlet pipe (7) and supplying it to the mill (4); A first dust collecting device (9) connected to the combustion gas discharge pipe (6) to collect contaminants and dust in the combustion gas; A combustion gas discharge path 60 for branching a part of the combustion gas discharged from the boiler 5 and supplying it to the coal storage tank 2; And a steam / hot water pipe (27) installed in the coal storage tank (2) for passing one of thermal fluids including steam and hot water. The steam / hot water pipe (27) includes; The wet coal in the coal storage tank 2 is dried by the transferred heat.

Hereinafter, with reference to the accompanying drawings will be described in detail the configuration and effect of the coal drying system using the exhaust gas as a sealing material according to the present invention.

3 is a configuration diagram of a coal drying system 1 using exhaust gas as a sealing material according to the first embodiment of the present invention. Referring to FIG. 3, a coal drying system 1 as a first embodiment of the present invention is a coal storage tank 2, a coal feeder 3, a mill 4, a boiler (compared with the prior art shown in FIG. 1). 5) The same applies to the point of having the combustion gas discharge pipe 6, the air inlet pipe 7, the air preheater 8, the first dust collector 9 and the stack 10. However, in the coal drying system 1 according to the first embodiment of the present invention, a part of the combustion gas exhausted from the boiler 5 is recovered and recycled to dry the wet coal in the coal storage tank 2. There is a difference in construction from the prior art of FIG.

Referring to the coal drying system 1 according to the first embodiment of the present invention shown in FIG. 3, the air preheater 8 is externally introduced into the air inlet pipe 7 by the heat of the combustion gas discharged from the boiler 5. Some of the preheating air passing through the air preheater (8) enters the boiler (5) and is used as air for combustion of coal, and the remainder is branched at the preheating air branch point (7a) to the primary air blower (11a). It is pressurized by and supplied to the fine powder 4.

On the other hand, the exhaust flue gas of the boiler 5 is branched at two flue gas branch points 6a and 60a while being guided through the flue gas discharge pipe 6 and fed into the coal storage tank 2. The combustion gas before exiting the boiler 5 and still entering the air preheater 8 is hot, and the combustion gas after passing through the air preheater 8 and the first dust collector 9 becomes relatively low. The high temperature dry combustion gas taken out from the first combustion gas branch point contains a considerable amount of coal ash and dust therein, and if not removed, the combustion gas blower 11d may be damaged. After removing the coal ash and dust at (19) enters the combustion gas delivery path (60). The low temperature combustion gas branched from the combustion gas discharge pipe 6 at the second combustion gas branch point 60a passes through the first damper 61 for adjusting the flow rate, and then the high temperature combustion gas at the combustion gas confluence point 60b. Combined with

Since the combustion gas in the combustion gas delivery path 60 has a low pressure, the combustion gas is sent to the coal storage tank 2 by raising the pressure to the combustion gas blower 11d. At this time, the combustion gas blower 11d is preferably composed of a fan or a blower. The combustion gas is supplied into the coal storage tank 2 by the combustion gas supply unit 62 connected to the combustion gas delivery path 60 to be in direct contact with coal.

In the first embodiment of the present invention, the combustion gases of different temperatures are extracted and mixed at different points of the combustion gas discharge pipe 6, that is, at the first combustion gas branch point 6a and the second combustion gas branch point 60a. In the case of coal drying, when the heating temperature is high, depending on the type of coal, volatile matter in the coal may evaporate and there is a heat loss of the fuel. Therefore, the combustion gas whose temperature is lowered through the air preheater 8 is reduced to air. This is because it is necessary to reduce the temperature of the drying combustion gas by partially diluting the combustion gas having a high temperature before passing through the preheater 8. In other words, if the coal is dried using only the combustion gas discharged immediately from the boiler (5), there is a heat loss due to the evaporation of volatile matter in the coal a lot, so that the high temperature combustion gas and the low temperature combustion gas are mixed to an appropriate temperature. It is due to the consideration that it is more effective in terms of energy efficiency.

In the present invention, the composition of the combustion gas supplied to the coal storage tank (2) is different depending on the fuel composition and the excess air supply conditions, but oxygen of about 5% and 15% carbon dioxide, and some water vapor and the rest of nitrogen Consists of In general, since combustion does not proceed at an oxygen concentration of 15% or less, if the coal stored in the coal storage tank 2 is dried with a combustion gas having a high temperature as in the first embodiment of the present invention, even if the temperature of the coal increases, There is never enough oxygen to ignite the coal during the drying process.

That is, when the combustion gas is supplied to the coal storage tank 2, the coal storage tank 2 is almost blocked from the outside air, and the carbon dioxide gas contained in the combustion gas has a specific gravity higher than that of the air, so that the coal storage tank 2 is entirely lower than the coal storage tank 2. Since it is full, the oxygen concentration inside the coal storage tank 2 is low overall, and there is no possibility of spontaneous ignition inside the coal storage tank 2. However, in order to prevent accidents, it is also preferable to provide an oxygen or carbon dioxide gas concentration meter to adjust the amount of the combustion gas for sealing.

In FIG. 3, the combustion gas after drying the coal in the coal storage tank 2 is saturated with moisture, and the temperature rises to the upper portion of the coal storage tank 2. Then, the combustion gas wetted from the upper portion of the coal storage tank 2 is introduced into the coal dust collector 70 through the gas discharge pipe 71, and after removing the coal dust from the coal dust collector 70, the combustion gas delivery pipe 72. ) Is joined to the original combustion gas exhaust system, that is, the combustion gas discharge pipe (6), and then discharged to the atmosphere.

In this case, when the combustion gas is sent from the coal dust collector 72 to the combustion gas discharge pipe 6, it may be sent to the suction side of the first dust collecting device 9 through the exhaust blower 11e, as shown in FIG. Or you can send it directly without a blower.

Meanwhile, the coal dusts collected by the coal dust collector 70 may be supplied to the coal feeder 3 or the mill 4 to be used as combustion fuel in the boiler 5.

In FIG. 3, reference numeral 6b denotes a first combustion gas pipe connecting the combustion gas discharge pipe 6 and the second dust collecting device 19, and 6c connects the second dust collecting device 19 and the combustion gas confluence point 60b. Is the second combustion gas pipe.

In the coal drying system 1 of the present invention shown in FIG. 3, the temperature of the combustion gas saturated with moisture after drying the coal in the coal storage tank 2 will be about 60 ° C., and the volatile content in the coal is excessively high. In order to prevent evaporation and to achieve effective drying without heat loss, it is necessary to properly maintain the temperature of the combustion gas in the coal storage tank 2.

For this reason, the present invention, as shown in Figure 4, the temperature sensor 64 is installed in the vicinity of the combustion gas outlet 65 from which the combustion gas is discharged from the coal storage tank 2, the temperature sensor 64 The temperature of the combustion gas measured in the real time is sent to the control device 100, the control device 100 based on the measured value received from the temperature sensor 64, the opening degree of the second damper (63). Generates a control signal to adjust. The second damper 63 can adjust the flow rate of the combustion gas entering the combustion gas supply unit 62, the coal storage tank by the configuration of the control device 100, the temperature sensor 64 and the second damper (63). (2) The temperature in the inside can be properly maintained and managed.

In the present invention, the means for adjusting the inflow amount of the combustion gas by the control signal of the control device 100 is not necessarily limited to a specific mechanical configuration such as the second damper 63, in addition to the damper of the combustion gas Any means that can control the flow rate is applicable. In addition, the flow rate of the drying combustion gas entering the coal storage tank 2 may be controlled by adjusting the rotation speed of the electric motor of the blower that supplies the combustion gas instead of the second damper 63 or in parallel with the second damper 63. .

The present invention can maintain a constant dryness of coal by the control system of the combustion gas flow rate as shown in Figure 4, it is possible to reduce the power and heat for drying.

On the other hand, in the coal inlet located above the coal storage tank (2), only coal (C) pouring from the coal supply hopper (2a) enters the coal storage tank (2) and the combustion gas in the coal storage tank (2) does not flow out of a kind. It is preferable to install a coal input door 2b which operates on the same principle as the revolving door.

The coal inlet 2b is rotatably installed in the coal inlet in a direction intersecting the coal inlet, and has a plurality of blades along the rotational direction of the coal inlet 2b. And as the blades of the coal input door (2b) is rotated, the inlet is realized alternately between the closed state and the open state. Since the blades of the coal input door 2b are installed in close contact with the coal inlet, the gas inside the coal storage tank 2 is prevented from leaking to the outside, and only coal is allowed to enter the coal storage tank 2 as much as possible. .

If there is no such structure as the coal input door (2b), the internal and external air flows in and out of the coal as the coal is injected. If the combustion gas in the coal storage tank 2 leaks to the outside through the coal supply hopper 2a, it is serious. On the contrary, when the outside air flows into the coal storage tank 2, it causes the pollution and not only the obstacle of circulation of the combustion gas for drying but also the load of the combustion gas blower 11d (see FIG. 3) increases. .

And it is preferable to install a coal discharge door (2c) having the same structure as the coal input door (2b) to the coal discharged from the coal storage tank (2b) so that only coal out as possible and do not exchange air.

The coal discharge door 2c is also configured in the same manner as the coal injection door 2b. That is, the coal discharge door (2c) is rotatably installed in the coal discharge port in the direction to block the coal discharge port, a plurality of blades are provided along the direction in which the coal discharge door (2c) is rotated by the rotational movement of the blades The closed state and the open state of the coal discharge port are alternately realized.

The coal drying system 1 according to the first embodiment of the present invention shown in FIGS. 3 and 4 recovers the combustion gas discharged from the boiler 5 instead of simply discarding it and uses it for drying coal. Without drying the coal is excellent energy saving effect, and also prevents the coal from spontaneous ignition or explosion during the drying of the coal has a special effect in terms of securing safety.

5 is a configuration diagram of a coal drying system 1a using exhaust gas as a sealing material according to a second embodiment of the present invention. When comparing the coal drying system 1a of the second embodiment of the present invention shown in FIG. 5 with the coal drying system 1 of the first embodiment shown in FIG. 3, the combustion gas is mainly used to prevent spontaneous combustion or explosion of coal. It is only used as a sealing gas, and the thermal energy for drying coal is provided by steam or hot water flowing through a separate steam / hot water pipe 27.

Therefore, in the second embodiment of the present invention, the high temperature combustion gas before discharged from the boiler 5 and introduced into the air preheater 8 is not used, and the low temperature combustion gas is taken out only at the rear end of the first dust collector 9. To the coal storage tank (2). This low temperature combustion gas maintains a temperature of about 120 ~ 150 ℃, so the drying effect of coal is not large. Instead, the inert gas for sealing prevents coal from igniting or exploding due to low oxygen concentration in the combustion gas. It mainly plays a role as). The coal is heated and dried by steam or hot water flowing in the steam / hot water pipe 27 separately installed in the coal storage tank 2.

Since the steam / hot water pipe 27 has a tubular or duct-type heat transfer surface and has a large contact area with coal, coal can be efficiently heated and dried by steam or hot water. . As the coal is used, the coal gradually descends toward the feeder 3 and the fine powder 4, and comes into contact with the steam / hot water pipe 27 to rise in temperature and dry.

Sealing combustion gas and the steam generated by the heating of the coal in the coal storage tank (2) enters the coal dust collector (70) through the gas discharge pipe (71), where the coal dust is collected again the coal dust delivery path (73). Is sent to a coal feeder (3) or a mill (4). The combustion gas and steam from which the dust is removed from the coal dust collector 70 are discharged to the atmosphere, and unlike the first embodiment of FIG. 3, since the flow rate is not large, the original combustion gas exhaust system (ie, the combustion gas discharge pipe 6). You do not have to return to).

According to the second embodiment of the present invention shown in FIG. 5, steam or hot water can be directly supplied to the steam / hot water pipe 27 to supply heat to coal and reuse condensed water. It is highly efficient and can be installed and operated at a small cost. In addition, in the case of using hot water, there is a large amount of heat supply in the same heat transfer area compared to the case of steam supply, there is no water hammer action regardless of the design, there is an advantage that can be stored and used if there is any heat remaining in the system.

6 is a configuration diagram of a coal drying system 1b using exhaust gas as a sealing material according to a third embodiment of the present invention.

The third embodiment shown in FIG. 6 is a modified example combining the first embodiment and the second embodiment, and mixes the hot combustion gas and the low temperature combustion gas discharged from the boiler 5 as advantageous in the field process. The temperature of the combustion gas for sealing and drying can be adjusted appropriately. Thus, the combustion gas for sealing and drying, which is a mixture of the hot and low temperature combustion gas, is directly injected into the coal storage tank (2), and indirectly with the coal through the heat pipe. By contacting, the drying and sealing effect of the coal is simultaneously achieved.

Referring to FIG. 6, the coal drying system 1b according to the third embodiment of the present invention mixes the high temperature exhaust gas before the air preheater 8 is introduced with the low temperature exhaust gas after the air preheater 8 passes through the coal storage tank. (2), but is divided into a combustion gas supply part 62 and a heat transfer tube 67 at the third combustion gas branch point 68. The combustion gas supply unit 62 injects combustion gas in direct contact with coal in the same configuration as the first embodiment of FIG. 3 and the second embodiment of FIG. 5, and the heat transfer tube 67 is the second embodiment of FIG. 5. With the same configuration as the steam / hot water pipe 27 included in the example, the combustion gas is indirectly contacted with coal to heat and dry the coal.

The combustion gas passing through the heat transfer pipe 67 and the combustion gas and steam discharged from the coal storage tank 2 enter the coal dust collector 70 through the combustion gas discharge pipe 67a and the gas discharge pipe 71, respectively. Here, after the coal dust is collected, the collected coal dust is sent to the feeder (3) or the fine powder (4), and the remaining combustion gas is passed through the combustion gas delivery pipe (72), that is, the original combustion gas exhaust system. It enters the front end of the 1st dust collector 9 of the flue gas discharge pipe 6. As shown in FIG.

In the third embodiment of the present invention, the initial cost is high because the surface area of the heat transfer tube 67 that transfers the heat of the combustion gas is large, but the pressure loss is small because the combustion gas passes through the inside of the heat transfer tube 67. The power loss for circulating the combustion gas can be reduced.

In addition, in the third embodiment of the present invention, cooling and supplying combustion gas (sealed gas) may be adopted as an optional configuration in order to reduce power for transporting combustion gas.

Referring to FIG. 7, the fourth embodiment of the present invention does not supply combustion gas to the coal storage tank 2 but instead separates the coal between the coal storage tank 2 and the feeder 3 or before coal is supplied to the coal storage tank. The coal drying unit 200 is additionally installed to supply combustion gas to the coal drying unit 200 to safely dry the coal. The combustion gas supplied to the coal drying unit 200 is a high temperature combustion gas taken out before the air preheater 8 is drawn out of the combustion gas discharged from the boiler 5 and a low temperature taken out after the air preheater 8 passes. The combustion gas of is mixed and used appropriately.

The coal drying unit 200 is composed of a coal dryer 210 for drying coal by the combustion gas and a coal dust collector 70 for treating the exhaust gas from the coal dryer 210. In FIG. 8, the remaining components are the same as those in FIGS. 3, 4, 5, and 6, and thus detailed description thereof will be omitted.

8 is a detailed configuration diagram of the coal drying unit 200 shown in FIG. Referring to Figure 8, the coal dryer 210 included in the fourth embodiment of the present invention, conveys the coal (C) received from the coal storage tank (2) and aeration having a gap through which the combustion gas can pass A belt 212, a ventilation belt pulley 213 supporting and rotating the ventilation belt 212, a rocking roller 215 for providing a predetermined vibration to the ventilation belt 212, and the coal storage tank ( 2) is composed of an adjustable roller 214 for adjusting the amount of coal discharged from the vent belt 212, the coal dust collector 70 is discharged after drying the coal in the coal dryer (210) The waste gas is treated to collect dust, and the collected dust is sent to a coal feeder 3 or a mill 4 to be used as fuel in a boiler.

Referring to Figure 8 describes the coal drying action by the vent belt 212 of the coal dryer 210, the vent belt 212 is made of a heat-resistant cloth such as Teflon (PTFE) or silica fibers, or heat-resistant Like rubber or chain belt stoker structures, it is heat resistant and allows combustion gases to pass through.

The vent belt 212 is driven by the vent belt pulley 213, and when the vent belt 212 is transferred, the vent belt 212 from the coal hopper 20a by the adjustable roller 214 adjustable up and down The amount of coal (C) that is placed above is controlled. The adjustable roller 214 controls the supply amount of coal coming from the hopper outlet 20b and at the same time to spread the coal to a certain thickness on the vent belt 212, the combustion gas is a constant between the vent belt 212 and the coal bed To let them pass. The coal dried by the combustion gas passing through the vent belt 212 is transported after falling from the vent belt 212 and stored or used in another reservoir.

Meanwhile, the combustion gas may be supplied from the combustion gas supply pipe 69 under the ventilation belt 212 as shown in FIG. 8, or may be supplied between the upper belt and the lower belt of the ventilation belt 212 to provide the ventilation belt. It can also dry coal passing through and coal. The combustion gas after drying the coal is collected by the coal dust 77 in the coal dust collector 70, the collected dust 77 is sent to a coal feeder or a pulverizer, and the dry combustion gas from which the dust is removed is returned to normal. Return to the exhaust gas treatment system.

The rocking roller 215 swings up and down as necessary to give fluidity to the coal on the ventilation belt 212 to smoothly ventilate and allow the coal to dry evenly. Ventilation belt 212 has a sealed structure so that the amount of combustion gas leakage through the edge is not much, buried in the coal 217 and the lower belt leaked through the coal supply portion is falling coal coal dryer 210 Go to the bottom of the pool. The coal accumulated on the bottom of the coal dryer 210 is discharged toward the coal feeder or the pulverizer through the rotary valve 218 which can minimize the leakage of combustion gas, as in the principle of a revolving door generally used in a building.

In the coal drying system 1d according to the fourth embodiment of the present invention, the degree of drying of coal is controlled based on the temperature of the discharged combustion gas. When the temperature of the exhaust gas is sensed and sent to the control device (not shown in FIG. 4), the control device calculates a control amount for the control object. As a control method of adjusting the temperature of the combustion gas, the flow rate of the combustion gas flowing into the coal dryer 210 may be controlled using a damper (not shown) according to the temperature of the outlet of the coal dryer 210, or The dryness of the coal may be controlled by adjusting the position of the adjustable roller 214 to adjust the supply amount of coal or by adjusting the supply amount of coal by changing the speed of the electric motor driving the vent belt 212.

In the coal drying apparatus according to the fourth embodiment of the present invention, as shown in FIGS. 7 and 8, a coal drying unit 200 may be installed between the coal storage tank 2 and the feeder 3. Alternatively, the coal drying unit 200 may be installed at the front end of the coal storage tank 2. The coal drying unit 200 is to dry by applying hot air by the exhaust gas in the process of loading and transporting the coal on the vent belt 212, it can be installed in any process before the feeder (3).

In the coal drying system using the exhaust gas as a sealing material according to the present invention, the coal drying process is performed by directly drying coal using exhaust gas having a low oxygen concentration from a coal combustion plant or by heating and drying coal using the exhaust gas as a sealing material. To prevent spontaneous ignition and explosion and to minimize mechanical friction with coal, and to increase the efficiency of fuel to promote the efficient use of fuel resources. By using it as an advantage, it is possible to reduce the cost of coal purchase.

In addition, the coal drying system using the exhaust gas as a sealing material according to the present invention by lowering the temperature of the exhaust gas finally discharged to the atmosphere by recovering and using the exhaust gas from the coal combustion equipment to dry the coal, as a result the coal combustion equipment There is an advantage that can raise the efficiency of the best.

In addition, the conventional coal combustion equipment requires a lot of installation costs such as increasing the volume of the combustion equipment because the total calorific value decreases when the moisture in the coal is high, but when the coal drying system using the exhaust gas as a sealing material according to the present invention is applied, The availability of this much lower priced coal allows a wider range of fuel choices, resulting in a variety of effects, including smooth supply of coal, reduction of fuel purchase costs, and securing design space for combustion equipment.

In addition, there is a lot of moisture in the coal to prevent the operation of the facility due to the blockage caused by the coal processing process to facilitate the operation of the facility, improve the crushing degree of coal in the coal grinding process, and drying the coal inside the mill This reduces the power to crush coal. In addition, since the water is added in the process of burning coal, it is possible to operate according to the original design conditions of the combustion equipment, and thus the performance of the entire combustion equipment is improved.

When the present invention is applied, the greatest effect is to enable low- and low-cost fuels containing a lot of water and volatile matter, so that coal supply and demand can be smoothly and fuel selection can be expanded, resulting in a reduction in fuel purchase cost. Furthermore, there is an effect that can reduce the installation and operating costs of the combustion facility.

Claims

A boiler 5 for burning coal to generate steam;

A coal storage tank 2 storing coal;

A coal feeder (3) for transporting coal in the coal storage tank 2 by the required amount in the boiler 5;

A pulverizer 4 for pulverizing the coal received from the feeder 3 into fine powder and feeding it to the boiler 5;

Combustion gas discharge pipe (6) for discharging the combustion gas from the boiler (5);

An air inlet pipe 7 for introducing external air into the boiler 5;

An air preheater (8) for preheating external air in the air inlet pipe (7) by heat exchange between the combustion gas discharge pipe (6) and the air inlet pipe (7);

A preheated air delivery pipe (12) for branching preheated external air in the air inlet pipe (7) and supplying it to the mill (4);

A first dust collecting device (9) connected to the combustion gas discharge pipe (6) to collect contaminants and dust in the combustion gas; And

And a combustion gas discharge path 60 for branching a part of the combustion gas discharged from the boiler 5 and supplying it to the coal storage tank 2.

A coal drying system using exhaust gas as a sealing material, characterized in that the combustion gas introduced into the coal storage tank (2) dries wet coal in the coal storage tank (2).

The combustion gas introduced into the coal storage tank 2 through the combustion gas discharge path 60 is branched before the combustion gas discharged from the boiler 5 enters the air preheater 8. The exhaust gas sealing material, characterized in that the high-temperature combustion gas and the combustion gas discharged from the boiler 5 are mixed with the low-temperature combustion gas branched after passing through the first dust collector 9. Coal drying system

According to claim 1, Temperature sensor (64) for measuring the temperature of the combustion gas discharged from the coal storage tank (2);

A second damper 63 for adjusting a flow rate of the combustion gas flowing into the coal storage tank 2 from the combustion gas delivery path 60; And

And a control device 100 which receives the output of the temperature sensor 64 and adjusts the opening degree of the second damper 63 in response to the temperature of the combustion gas. Coal drying system using gas as sealant.

A boiler 5 for burning coal to generate steam;

A coal storage tank 2 storing coal;

A coal feeder (3) for transferring coal of the coal storage tank (2) by the required amount in the boiler (5);

A pulverizer (4) for pulverizing the coal received from the feeder (3) into a fine powder state and supplying it to the boiler (5);

An air inlet pipe 7 for introducing external air into the boiler 5;

An air preheater (8) for preheating the outside air in the air inlet pipe (7) by heat exchange between the combustion gas discharge pipe (6) and the air inlet pipe (7);

A first dust collecting device (9) connected to the combustion gas discharge pipe (6) to collect contaminants and dust in the combustion gas;

A combustion gas discharge path 60 for branching a part of the combustion gas discharged from the boiler 5 and supplying it to the coal storage tank 2; And

And a steam / hot water pipe (27) installed in the coal storage tank (2) for passing one of thermal fluids including steam and hot water.

A coal drying system using exhaust gas as a sealing material, characterized by drying the wet coal in the coal storage tank (2) by the heat transferred by the steam / hot water pipe (27).

5. The method according to claim 4, wherein the coal gas in the coal storage tank (2) is dried and the discharged combustion gas is treated to collect coal dust in the combustion gas, and the collected coal dust is sent to the feeder (3) and burned. The gas further comprises a coal dust collector (70) to send to the first dust collector (9); coal drying system using the exhaust gas as a sealing material.

The combustion gas introduced into the coal storage tank (2) through the combustion gas discharge path (60) is characterized in that the combustion gas discharged from the boiler (5) passes through the first dust collector (9). A coal drying system using exhaust gas as a sealing material, wherein the combustion gas is a low-temperature combustion gas branched out later.

A boiler 5 for burning coal to generate steam;

A coal storage tank 2 storing coal;

An air inlet pipe 7 for introducing external air into the boiler 5;

A combustion gas discharge path 60 for branching a part of the combustion gas discharged from the boiler 5 and supplying it to the coal storage tank 2;

A combustion gas supply unit 62 which directly contacts a portion of the combustion gas supplied through the combustion gas discharge path 60 with coal in the coal storage tank 2; And

And a heat transfer pipe (傳熱管, 67) configured to pass the rest of the combustion gas supplied through the combustion gas discharge path 60 to indirectly transfer the heat of the combustion gas to coal.

A coal drying system using exhaust gas as a sealing material, characterized by drying the wet coal in the coal storage tank (2) by the combustion gas supplied to the coal storage tank (2).

The second method of claim 8, wherein the second combustion chamber receives the high temperature combustion gas branched from the combustion gas before entering the air preheater 8, collects contaminants and dust, and joins the combustion gas delivery path 60. A coal drying system using exhaust gas as a sealing material, further comprising a dust collector 19.

A boiler 5 for burning coal to generate steam;

A coal storage tank 2 storing coal;

A coal feeder (3) for transporting coal in a quantity necessary in the boiler (5);

An air inlet pipe 7 for introducing external air into the boiler 5;

A coal drying unit (200) installed between the coal storage tank (2) and the feeder (3) to dry the wet coal from the coal storage tank (2); And

And a combustion gas discharge path (60) for branching a part of the combustion gas discharged from the boiler (5) and supplying the combustion gas to the coal dryer (210).

The method of claim 10, wherein the coal drying unit 200,

Aeration belt pulley for conveying the coal (C) received from the coal storage tank (2) and the ventilation belt pulley having a gap through which the combustion gas can pass, and supports and rotates the ventilation belt (212) 213, an oscillation roller 215 for providing a predetermined vibration to the vent belt 212, and an adjustable to adjust the amount of coal discharged from the coal storage tank (2) and loaded on the vent belt (212) A coal dryer 210 comprising a roller 214; And

And a coal dust collector (70) for collecting the dust by treating the discharged combustion gas after drying the coal in the coal dryer (210). The coal drying system using exhaust gas as a sealing material.

A boiler 5 for burning coal to generate steam;

A coal storage tank 2 storing coal;

An air inlet pipe 7 for introducing external air into the boiler 5;

A coal drying unit 200 installed at a front end of the coal storage tank 2 to dry coal to be transferred to the coal storage tank 2; And

The method of claim 12, wherein the coal drying unit 200,

A conveyance belt 212 having a gap through which the combustion gas can pass, a vent belt pulley 213 for supporting and rotating the vent belt 212, and a predetermined vibration is applied to the vent belt 212. A coal dryer (210) comprising a rocking roller (215) to provide, and an adjustable roller (214) for adjusting the amount of coal loaded onto the vent belt (212); And

The method according to any one of claims 1 to 13,

The coal storage tank 2 includes a coal entrance door 2b installed on a coal inlet through which coal is introduced into the coal discharge door 2c and a coal discharge door 2c installed on a coal discharge door through which coal is discharged toward the coal feeder 3. ,

The coal inlet 2b is rotatably installed in the coal inlet in a direction intersecting the coal inlet, and includes a plurality of blades along the rotational direction of the coal inlet. Alternate between closed and open conditions,

The coal discharge door 2c is rotatably installed in the coal discharge port in a direction intersecting the coal discharge port, and includes a plurality of blades along the rotation direction thereof, and the coal discharge port is closed and opened by rotating the blades. A coal drying system using exhaust gas as a sealing material, characterized by alternating states.