JPH1043624A - Mill warming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable early warming of a mill not in operation without sending excess air into the furnace of a coal burning boiler by installing a heater which uses hot water or steam on the periphery of the lower part of a mill casing. SOLUTION: A mill 1 installed in the coal burning boiler of a electric power plant crushes coal 3, which is supplied by a coal supply machine 5 from a coal banker 2 into a mill casing 7 through coal supply pipe 6, between a crushing table 9 and a crushing roller 11. A heater 21 which uses hot water or steam is installed on the periphery of the lower part of the casing 7 of the mill 1. When the operation of the mill 1 is stopped, a valve 29 is opened, hot water is supplied from supply piping 24 into a chamber 23 and discharged from discharge piping 25, so that the temperature decrease of the mill 1 is checked to warm up the mill 1. When hot water alone can not supply heat necessary for the warming, a valve 32 is opened, steam and hot water are supplied from the piping 24 into the chamber 23.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mill warming device.

[0002]

2. Description of the Related Art FIG. 4 shows an example of a mill 1 provided in a coal-fired boiler of a power plant. As shown in the drawing, the mill 1 transfers coal 3 of a coal bunker 2 to a coal feeder motor 4 as shown in FIG.
Is supplied into the mill casing 7 through a coal supply pipe 6 by a coal supply machine 5 capable of adjusting the coal supply amount, and the coal 3 introduced from the coal supply pipe 6 is supplied to an electric motor. An upper surface of a crushing table 9 that is driven to rotate via a connected speed reducer 8 and a crushing roller 11 that rolls following the rotation of the crushing table 9 while being pressed against the upper surface of the crushing table 9 by a pressing device 10. Between the crushing.

[0003] The powder 12 produced by the pulverization is blown up in the mill casing 7 by primary air 14 for transport from an outlet port 13 provided annularly so as to surround the pulverizing table 9, 7 is conveyed upward through a slit opening 17 formed by raising an outer edge 16 of a cut formed at a plurality of locations in a circumferential direction of a funnel-shaped reject chute 15 that partitions the inside of the funnel up and down, and further guided upward. The powder 12 is guided to a rotary classifier 19 that is provided in the upper portion of the mill casing 7 and is rotationally driven by a classifier motor 18 to be classified. Only fine pulverized coal having a predetermined particle size or less is milled. The coal is supplied to a burner of a coal-fired boiler (not shown) through a pulverized coal pipe 20 connected to the top.

The coarse coal pulverized by the classifier 19 is
The slope between the slit openings 17 of the reject chute 15 is slid down and returned from the lower end of the reject chute 15 to the center of the pulverizing table 9, together with the coal 3 (raw coal) fed from the coal feed pipe 6. It is designed to be crushed.

[0005]

The mill 1 as described above has the following features.
Usually, a plurality of (for example, six) units are provided for one boiler, and the number of operating units is appropriately increased or decreased according to the load of the boiler, and the mill 1 is started and stopped, but the mill 1 is stopped. If the mill 1 is left in this state, the temperature of the mill 1 decreases, and even if the mill 1 is started again, it takes a long time until the mill 1 warms up to some extent, and during that time, pulverized coal cannot be supplied. Generally, hot air that has passed through an air preheater (not shown) and cold air that has bypassed the air preheater are mixed and supplied to the blowing port 13 so that the mill outlet temperature becomes a set value. The warming of the mill 1 is performed.

However, the air supplied into the mill 1 is sent as excess air from a burner of a coal-fired boiler (not shown) into a furnace through a pulverized coal pipe 20, and this is the control system of the boiler. Become a disturbance of
Imbalance of air in the furnace, NOx increases the exhaust gas O ₂
Has the disadvantage of increasing.

The present invention has been made in view of the above circumstances, and it is possible to warm a stopped mill without sending excess air into a furnace of a coal-fired boiler, suppress disturbance in a control system, and reduce NOx. It is an object of the present invention to provide a mill warming device capable of suppressing an increase in the temperature.

[0008]

SUMMARY OF THE INVENTION The present invention relates to a warming device for a mill, wherein a heating device using hot water or steam is provided on the lower periphery of the mill casing.

In the mill warming device,
A heating device is formed by forming a chamber on the lower outer periphery of the mill casing, connecting a supply pipe for supplying hot water or steam to the chamber, and connecting a discharge pipe for discharging the supplied hot water or steam to the chamber. be able to.

In the warming device for a mill, a heat transfer tube is wound in a coil shape around the lower periphery of the mill casing, and a supply pipe for supplying hot water or steam is connected to one end of the heat transfer tube. A heating device may be configured by connecting a discharge pipe for discharging the supplied hot water or steam to the other end of the heat pipe.

According to the above means, the following effects can be obtained.

When the operation of the mill is stopped, hot water or steam is supplied to the heating device, the temperature of the mill is prevented from lowering, and the mill is warmed.

As a result, for the warming of the mill,
Prevents the excess air is sent into the furnace of a coal-fired boiler, not imbalance of the air in the furnace, the exhaust gas O ₂ is NOx also not increase without the increase.

Further, in a power plant, a part of the hot water is discarded after being cooled. However, by using it for warming the mill as in the present invention, the efficiency of the plant is improved.

In the above-described mill warming apparatus, a chamber is formed on the outer periphery of the lower portion of the mill casing, and a supply pipe for supplying hot water or steam is connected to the chamber, and a discharge pipe for discharging the supplied hot water or steam is provided. When the pipe is connected to form a heating device, when the operation of the mill is stopped, hot water or steam is supplied from the supply pipe into the chamber, discharged from the discharge pipe, and the temperature of the mill is prevented from lowering. Is performed.

Further, in the above-described warming apparatus for a mill, a heat transfer tube is wound in a coil shape around the lower periphery of the mill casing, and a supply pipe for supplying hot water or steam is connected to one end of the heat transfer tube. When the heating device is configured by connecting a discharge pipe for discharging the supplied hot water or steam to the other end of the mill, when the operation of the mill is stopped, the hot water or steam is supplied from the supply pipe to one end of the heat transfer pipe. Discharged from the end, the temperature of the mill is prevented from dropping, and the mill is warmed.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 show an example of an embodiment of the present invention. In the drawings, the portions denoted by the same reference numerals as those in FIG. 4 represent the same components, and the basic configuration is shown in FIG. It is the same as the conventional one shown here, but the feature of this illustrated example is
As shown in FIG. 1, a heating device 21 using hot water or steam is provided on the outer periphery of the lower portion of the mill casing 7.

The hot water is generated in a coal-fired boiler of a power plant, and the steam after driving a steam turbine is transferred to a condenser 22.
The steam condensed is used, and the steam generated from a coal-fired boiler is used.

In the example shown in FIGS. 1 and 2, the heating device 21 is provided on the outer periphery of the lower part of the mill casing 7.
3, a supply pipe 24 for supplying hot water or steam is connected to the chamber 23, and a discharge pipe 25 for discharging the supplied hot water or steam is connected to the chamber 23. A partition plate 26 for preventing the hot water or steam supplied from the supply pipe 24 from being discharged from the discharge pipe 25 before reaching the inside of the chamber 23 is provided near the connection portion between the supply pipe 24 and the discharge pipe 25 in 23. It is attached.

In the drawing, reference numeral 27 denotes an expansion joint for absorbing vibration provided in the supply pipe 24;
Is an expansion joint for absorbing vibration provided in the middle of the discharge pipe 25, 29 is a valve provided in the middle of the supply pipe 24, 30 is a steam pipe connected in the middle of the supply pipe 24 upstream of the valve 29, and 31 is steam Piping 3
A check valve 32 provided in the middle of the steam pipe 30 is provided upstream of the check valve 31 in the middle of the steam pipe 30.

Next, the operation of the illustrated example will be described.

When the operation of the mill 1 is stopped, the valve 29
Is opened, hot water is supplied from the supply pipe 24 into the chamber 23, and is discharged from the discharge pipe 25, so that the temperature of the mill 1 is prevented from lowering, and the mill 1 is warmed.

When the amount of heat required for warming the mill 1 cannot be obtained by the hot water alone, the valve 32 is opened, and steam is supplied from the supply pipe 24 into the chamber 23 together with the hot water.

During the warming of the mill 1, the mill 1
A primary air damper (not shown) provided in the middle of a duct for supplying primary air 14 to the mill and a mill outlet damper (not shown) provided in the middle of the pulverized coal pipe 20 are fully closed.

As a result, the mill 1 is warmed up.
Surplus air is sent into the furnace of a coal-fired boiler
And the balance of air in the furnace is not lost,
Gas O _TwoAnd NOx does not increase.

Further, in the power plant, a part of the hot water is cooled and then discarded.
The use for warming the mill 1 leads to an improvement in plant efficiency.

In this way, the stopped mill 1 can be warmed without sending excess air into the furnace of the coal-fired boiler, the increase in NOx can be suppressed, and the effective use of hot water can be improved. This can improve plant efficiency.

FIG. 3 shows another example of the embodiment of the present invention. In the figure, the parts denoted by the same reference numerals as those in FIG. A heat pipe 33 is wound in a coil shape, and a supply pipe 24 for supplying hot water or steam is connected to one end of the heat transfer pipe 33.
The other end of the heat transfer tube 33 is connected to a discharge pipe 25 for discharging the supplied hot water or steam, to constitute the heating device 21.

In the example shown in FIG. 3, when the operation of the mill 1 is stopped, the valve 29 is opened and hot water is supplied to the supply pipe 2.
The heat is supplied from one end of the heat transfer tube 33 to one end of the heat transfer tube 33, and discharged from the other end.

When the amount of heat required for warming the mill 1 cannot be obtained by the hot water alone, the valve 32 is opened, and steam is supplied from the supply pipe 24 to the heat transfer pipe 3 together with the hot water.
3.

As in the case of the example of FIG. 1, during the warming of the mill 1, a primary air damper (not shown) provided in the middle of a duct for supplying the primary air 14 to the mill 1, and a pulverized coal The mill outlet damper (not shown) provided in the middle of the pipe 20 is fully closed.

As a result, also in the example shown in FIG. 3, excessive air is prevented from being sent into the furnace of the coal-fired boiler due to the warming of the mill 1, and the air balance in the furnace is not lost. N without increasing exhaust gas O ₂
Ox does not increase and leads to an improvement in plant efficiency.

In this way, the stopped mill 1 can be warmed without sending excess air into the furnace of the coal-fired boiler, the increase of NOx can be suppressed, and the effective use of hot water can be improved. This can improve plant efficiency.

The mill warming device of the present invention comprises:
It is needless to say that the present invention is not limited to the illustrated example described above, and various changes can be made without departing from the scope of the present invention.

[0036]

As described above, the first aspect of the present invention is as described above.
According to the warming apparatus for a mill described in (3), it is possible to perform warming of a stopped mill without sending excess air into a furnace of a coal-fired boiler, thereby suppressing an increase in NOx, In addition, effective use of hot water can be achieved, and an excellent effect of improving plant efficiency can be obtained.

[Brief description of the drawings]

FIG. 1 is an overall schematic configuration diagram of an example of an embodiment of the present invention.

FIG. 2 is an enlarged plan sectional view of a main part of an example of an embodiment of the present invention.

FIG. 3 is an overall schematic configuration diagram of another example of an embodiment of the present invention.

FIG. 4 is an overall schematic configuration diagram of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mill 7 Mill casing 21 Heating device 23 Chamber 24 Supply pipe 25 Discharge pipe 33 Heat transfer pipe

Claims (3)

[Claims] 1. A warming device for a mill, wherein a heating device using hot water or steam is provided on an outer periphery of a lower portion of the mill casing. 2. A chamber is formed on a lower outer periphery of the mill casing, and a supply pipe for supplying hot water or steam is connected to the chamber, and a discharge pipe for discharging the supplied hot water or steam is connected to the chamber. The warming device for a mill according to claim 1, wherein the device comprises a heating device. 3. A heat transfer tube is wound in a coil shape around the lower periphery of the mill casing, a supply pipe for supplying hot water or steam is connected to one end of the heat transfer tube, and the heat transfer tube is supplied to the other end of the heat transfer tube. The warming device for a mill according to claim 1, wherein the heating device is configured by connecting a discharge pipe for discharging hot water or steam.