KR101187046B1 - System for Drying Coal - Google Patents

Abstract

A coal drying system is disclosed. The coal drying system is a boiler that generates steam and discharges flue gas by burning coal in fine powder, a condenser that condenses and removes moisture from the flue gas, and a heat exchanger that heats condensed flue gas by using waste heat of the flue gas emitted from the boiler. And a pulverizer for drying the finely divided coal using the heated flue gas.

Description

Coal Drying System {System for Drying Coal}

The present invention relates to coal-fired power generation, and more particularly to a coal drying system for drying coal to be burned.

In large-scale workplaces that require large amounts of thermal energy, such as thermal power plants and steel mills, coal is mainly used as fuel. Coal is the lowest-cost and most abundant reserve of fossil fuels and is a stable fuel supply. However, coal has a disadvantage in that the facilities for combustion are complicated, and various problems are generated in the process of transmitting combustion and heat, and the facilities are complicated to reduce such problems.

In large-scale coal-fired power plants, primary air heated by using waste heat from flue gas is supplied to the mill and used as a medium for drying and transporting coal in the mill. At this time, the primary air used is air in the air, is injected with coal in a state containing moisture proportional to the absolute humidity in the air, the heat energy loss due to the latent heat loss of moisture during combustion occurs. have.

In addition, when the air in the atmosphere is used as the primary air, the sub-bituminous coal having high spontaneous flammability characteristics by the oxidation reaction with oxygen has a problem in that the possibility of spontaneous ignition and explosion during the fine grinding process increases according to the high oxygen content in the atmosphere. . In particular, as the consumption of low-grade sub-bituminous coal with high spontaneous combustion has recently increased, this problem becomes more serious.

The present invention is to provide a coal drying system for drying the coal by supplying the exhaust gas and the heated flue gas to the fine powder and the coal storage tank.

According to one aspect of the present invention, a coal drying system for drying coal using exhaust gas is disclosed.

Coal drying system according to an embodiment of the present invention uses a boiler to generate steam and discharge the exhaust gas by burning coal in the fine powder state, a condenser to condense and remove the moisture of the exhaust gas, waste heat of the exhaust gas discharged from the boiler A heat exchanger for heating the condensed exhaust gas and a pulverizer for drying finely divided coal using the heated exhaust gas.

Further comprising a coal storage tank for drying the stored coal by using the heated exhaust gas.

Further comprising a dust collector for removing the dust contained in the exhaust gas discharged from the boiler, the exhaust gas passing through the dust collector is delivered to the condenser.

The condenser condenses water in the exhaust gas using sea water.

The pulverizer supplies the finely divided coal to the boiler using the heated flue gas.

According to another aspect of the present invention, a coal drying system for drying coal using exhaust gas is disclosed.

Coal drying system according to an embodiment of the present invention is a coal storage tank including a spray pipe for injecting the heated exhaust gas to remove the moisture and the stored coal and the exhaust gas and coal particles containing water from the coal storage tank to receive the moisture It includes a cyclone to separate and discharge the exhaust gas containing.

The injection pipe is elliptical in cross section, and the major axis of the ellipse is vertical.

The injection pipe includes an injection nozzle formed in a shape projecting in a semi-conical shape, which is opened on the outer surface.

The injection pipe is formed in plural on both sides of the injection pipe on the basis of the long axis.

The cyclone includes a bag filter separating the exhaust gas containing the water and the coal particles.

The exhaust gas containing the moisture passes through the bag filter and is discharged into the atmosphere, and the coal particles are stored in the cyclone.

The present invention can dry the coal by removing the moisture and supplying the heated flue gas to the mill and the coal storage tank.

In addition, the present invention can reduce the possibility of fire in the differentiator that can occur when using low-grade coal.

In addition, the present invention can reduce the moisture content of coal in advance to reduce the latent heat loss of evaporation of water during coal combustion.

1 is a schematic view showing the configuration of a conventional coal combustion system.
2 is a schematic view showing the configuration of an improved coal combustion system.
3 is a view showing the structure of a coal reservoir and a cyclone of the coal combustion system of FIG.
Figure 4 is a view showing the structure of the injection pipe installed in the coal storage tank.

The present invention may be variously modified and have various embodiments, and specific embodiments will be illustrated in the drawings and described in detail with reference to the accompanying drawings. It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. In addition, numerals used in the description of the present invention are merely an identifier for distinguishing one component from another.

Also, in this specification, when an element is referred to as being "connected" or "connected" with another element, the element may be directly connected or directly connected to the other element, It should be understood that, unless an opposite description is present, it may be connected or connected via another element in the middle.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, the same reference numerals will be used for the same means regardless of the reference numerals in order to facilitate the overall understanding.

1 is a configuration diagram schematically showing the configuration of a conventional coal combustion system. In FIG. 1, the coal drying in the existing coal combustion system will be described.

Referring to Figure 1, the existing coal combustion system (Raw Coal Bunker) (10), Pulverizer (30), Boiler (40), Heat Exchanger (50), Dust Collector (60), Desulfurization apparatus 70, stack 80 and primary air blower (100).

The coal storage tank 10 stores coal used as fuel.

The fine powder 30 receives coal from the coal storage tank 10, pulverizes the coal into fine powder, and then dry. Here, the fine powder 30 receives the primary air heated from the primary air blower 100 to dry the coal.

Boiler 40 receives the fine powder of coal from the fine powder 40 to burn and generate steam.

The heat exchanger 50 heats the primary air by heat-exchanging the exhaust gas discharged from the boiler 40 and the primary air introduced from the atmosphere. That is, the primary air used for coal drying in the mill 30 is heated using waste heat of exhaust gas.

Since primary air is air in the atmosphere, it contains moisture proportional to the absolute humidity in the atmosphere. Thus, the primary air is injected into the boiler 40 from the fine powder 30 together with coal in a state containing moisture, and thermal energy loss occurs due to latent heat loss of evaporation of water during combustion.

In addition, primary air has a high oxygen content like the atmosphere. Thus, when coal such as sub-bituminous coal having high spontaneous combustion by oxidation is used, the possibility of spontaneous ignition and explosion in the fine powder 30 during the grinding process increases.

The primary air blower 100 pressurizes the heated primary air and supplies the same to the powder 40.

The dust collector 60 collects dust contained in the exhaust gas.

The desulfurization apparatus 70 removes sulfur of exhaust gas.

The chimney 80 discharges exhaust gas into the atmosphere.

2 is a schematic view showing the configuration of an improved coal combustion system. In FIG. 2, a coal combustion system for drying coal using exhaust gas will be described. Hereinafter, a description of components that overlap with FIG. 1 will be omitted, and only different components will be described.

Referring to FIG. 2, an improved coal combustion system includes a Raw Coal Bunker 10, a Cyclone 20, a Pulverizer 30, a Boiler 40, a heat exchanger. 50, a dust collector 60, a desulfurization apparatus 70, a stack 80, a condenser 90, a primary air blower 100, and an exhaust gas blower 110.

The condenser 90 condenses and removes moisture of exhaust gas passing through the dust collector 60. At this time, the condenser 90 may condense and remove the moisture of the exhaust gas using sea water.

The heat exchanger 50 heats the dried exhaust gas using waste heat of the exhaust gas discharged from the boiler 40 in order to prevent a temperature drop of the dried exhaust gas supplied from the condenser 90.

The primary air blower 100 receives the dried and heated flue gas from the heat exchanger 50 and supplies it to the mill 30. Accordingly, the fine powder 30 is used to dry the finely divided coal using the dried and heated exhaust gas.

As such, when the coal is dried in the fine powder 30 using the dried and heated flue gas, the possibility of spontaneous ignition and explosion in the fine powder 30 during the differentiation process is reduced, and the water vaporizes during combustion in the boiler 40. The heat energy loss due to latent heat loss can be reduced.

That is, since the exhaust gas has a low oxygen content (less than about 5%) in nature, the possibility of oxidation reaction with coal is greatly reduced. Thus, even in the process of grinding coal having high possibility of spontaneous combustion, the possibility of fire and explosion in the mill 30 is reduced.

If the flue gas is simply circulated to the pulverizer 30 to dry coal in the pulverizer 30, moisture contained in the coal itself is evaporated in the combustion process and discharged from the boiler 40 along with the flue gas to circulate. Accordingly, the moisture content of the circulated flue gas is gradually accumulated to increase the drying efficiency in the fine powder 30 and the accumulation of heat loss in the combustion process due to moisture.

Therefore, as shown in FIG. 2, a condenser 90 using seawater is used for drying the circulated exhaust gas. That is, the condenser 90 condenses and removes moisture of the circulated exhaust gas, and the heat exchanger 50 heats the circulated exhaust gas using waste heat of the exhaust gas discharged from the boiler 40.

By circulating the exhaust gas using the exhaust gas passing through the dust collector 60, it is possible to prevent the blockage of the air transfer pipe due to the dust contained in the exhaust gas and the ash circulation supply in the boiler 40.

The exhaust gas blower 110 supplies the dried and heated exhaust gas to the coal storage tank 10 through the condenser 90 and the heat exchanger 50. Accordingly, the coal storage tank 10 to dry the stored coal using the dried and heated exhaust gas. At this time, after the exhaust gas dried and heated in the coal storage tank 10 comes into contact with coal, the exhaust gas containing coal particles and water generated therein rises and is delivered to the cyclone 20.

The cyclone 20 separates and discharges the exhaust gas containing coal particles and water delivered from the coal storage tank 10. That is, exhaust gas containing moisture is discharged to the atmosphere, and coal particles are delivered to the fine powder 30.

The coal storage tank 10 and the cyclone 20 will be described later in detail with reference to FIGS. 3 and 4.

3 is a view showing the structure of the coal reservoir and the cyclone of the coal combustion system of FIG.

Referring to FIG. 3, the coal storage tank 10 may include a gate valve 16 installed in a coal supply pipe 17 through which coal is supplied at the upper portion thereof, and a rotary feeder for supplying stored coal to the fine powder 30. Feeder 18, and the injection pipe 12 is injected and injected dried and heated exhaust gas delivered from the exhaust gas blower 110.

The cyclone 20 is connected through a gas transfer pipe 18 connected to the upper portion of the coal storage tank 10, and a bag filter 22 is connected to the gas discharge pipe 21 connected to the upper portion of the cyclone 20. Is installed.

As shown in FIG. 3, the injection pipe 12 is installed in the middle or / and the lower part of the coal storage tank 10 in the form of a manifolder having a plurality of injection nozzles 14. That is, the injection nozzles 14 may be arranged in a line on the side surface of the injection pipe 12 so that the exhaust gas is injected toward the lower side. The structure of the injection pipe 12 is mentioned later in detail with reference to FIG.

The injected drying exhaust gas is injected downward and then moved between the pores of the coal particles to remove surface moisture attached to the coal particles and discharged through the gas transfer pipe 18 connected to the upper part of the coal storage tank 10 to form a cyclone. Go to (20). In this case, the exhaust gas discharged may include moisture and may be discharged together with coal particles.

Flue gas and coal particles containing water are moved to the cyclone 20 and then separated by a bag filter 22. That is, the bag filter passes the exhaust gas containing water and discharges it to the atmosphere, and does not allow coal particles to pass through. Coal particles that do not pass through the bag filter move to the bottom of the cyclone 20 and accumulate.

4 is a view showing the structure of the injection pipe installed in the coal storage tank.

4, the cross section of the injection pipe 12 is an ellipse, and the long axis of an ellipse becomes a vertical direction. In addition, a plurality of injection nozzles 14 are formed in a row on both sides of the injection pipe 12 with respect to the long axis. The spray nozzle 14 has a shape projecting in a semi-conical shape which is downwardly opened on the outer surface of the spray tube 12.

Such a structure of the injection pipe 12 is to minimize the disturbance of the movement of coal by the injection pipe 12 because of the characteristics of the coal storage tank 10 in which coal moves downward by its own weight, Therefore, it is a structure for minimizing the contact area of the injection pipe 12 in contact with coal.

In addition, the structure of the injection nozzle 14 is for preventing coal from moving downward by self weight and blocking the injection nozzle 14, and is opened in the same downward direction as the moving direction (lower direction) of coal. Through this structure, friction between the injection nozzle 14 and the coal can be reduced, and clogging of the injection nozzle 14 can be prevented, and the drying effect of the coal can be increased by maximizing the residence time of the exhaust gas in the coal.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention as defined in the appended claims. It will be understood that the invention may be varied and varied without departing from the scope of the invention.

10: coal storage tank
20: cyclone
30: powder
40: boiler
50: heat exchanger
60: dust collector
70: desulfurization apparatus
80: stack
90: condenser
100: primary air blower
110: flue gas blower

Claims (11)

A boiler for generating steam and discharging exhaust gas by burning coal in fine powder;
A condenser to condense and remove moisture of the exhaust gas;
A heat exchanger for heating the condensed exhaust gas by using waste heat of the exhaust gas discharged from the boiler;
A powder mill for drying finely divided coal using the heated exhaust gas;
A coal storage tank for drying the stored coal using the heated exhaust gas; And
Including a dust collector for removing dust contained in the exhaust gas discharged from the boiler,
Coal drying system characterized in that the exhaust gas passing through the dust collector is delivered to the condenser.
delete delete The method of claim 1,
The condenser is a coal drying system, characterized in that to condense the water of the exhaust gas using sea water.
The method of claim 1,
And the pulverizer supplies the finely divided coal to the boiler using the heated exhaust gas.
delete delete delete delete delete delete

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