JPS5818018A - Controller for ignition and extinguishing of burner - Google Patents

Abstract

PURPOSE:To reduce use of an auxiliary burner to a minimum and to widen a load control range, by extiguishing the auxiliary burner when it attains to a state of a self combustion range by watching coal quantity/primary air quantity, a state of a flame and a load factor of a crusher. CONSTITUTION:This device is so constituted that an auxiliary burner is extinguished when self combustion becomes possible by a method wherein coal quantity to be fed to a crusher is detected by a coal quantity detector 50, primary air quantity to be supplied to a burner through the crusher is measured by a primary air flow meter 51, which are made into coefficients by a divider 52, a present value of coal/air is compared and judged by a coal/air comparator 53 as to whether it is more than a specified value or not, and in addition to the above states of a pulverized coal burner's flame, mill differential pressure and primary air differential pressure are detected.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a combustion device using pulverized coal as fuel, and particularly to a burner point extinguishing control device therefor.

In recent years, due to the shortage of petroleum energy, coal-fired boilers have been actively considered as commercial boilers.

In planning the construction of power generation facilities using coal-fired boilers, due to the expansion of nuclear power generation facilities, (1) the boiler will have to be started and stopped many times;

(2) The range of boiler load fluctuation is large.

(3) The time given for starting and stopping the boiler is short.

There is a demand for the so-called intermediate load thermal power characteristics that were previously required for oil and gas (LNG XLPG) combustion boilers, such as, and there is also a demand for coal-fired thermal power that reduces the use of oil as much as possible.

For this reason, it is desirable for combustion equipment that uses pulverized coal as fuel to have a wide load control range, and to reduce oil consumption as much as possible, the pulverized coal burner should be turned on from the early stage of boiler startup. In addition, all pulverizers must be able to operate from the early stage of boiler startup, and the pulverizers must be able to operate even in the boiler's low load range.

Figure 1 is a schematic diagram of a boiler device that uses pulverized coal as fuel.
FIG. 2 is a schematic configuration diagram of a crusher attached to the boiler device, and FIG. 3 is an enlarged sectional view of the vicinity of the burner section.

In FIG. 1, coal 23 charged into a coal hanger 1 passes through a coal gate 2, is fed into one gate by a coal feeder 3, passes through a coal feed pipe 4, and is fed into a crusher 5. The detailed configuration of the crusher 5 will be explained later using FIG. 2.

A part of the air sent from the forced draft fan 10 and the primary draft fan 9 is heated by passing through an air preheater 12t, and is sent to each crusher 5@ through a heated air duct 13t. On the other hand, the remainder of the air sent from the primary ventilation fan 9 passes through a cold air duct (14t) and is sent to each pulverizer (5). By adjusting the opening degree and the opening degree of the cold air damper 20 attached to the cold air duct 14 side, the temperature of the supplied air is adjusted by K, and the air passes through the hot air pipe 21 to the crusher population. Air is supplied to each pulverizer 5 while the air volume is adjusted by the damper 22.Next, the schematic structure of the pulverizer 5 will be explained with reference to FIG. 2. The crusher 5 has a ball mill structure, and includes a coal feeding pipe 24 for coal 23, a coal crushing section 25, a power transmission section 26,
It is equipped with a classifier 27, a nitrogen gas compression cylinder 28, and the like. The coal crushing section 25 includes an upper ring 29 pressed by a compression cylinder 28, a lower ring 30, and a plurality of inner rings 9. It is mainly composed of an empty pole 31. In the figure, 32Fi pulverized coal outlet pipe, 33 foreign matter discharge port, 34 mill housing, 35t
j return chute, 3sFi coarse coal discharge port.

The coal 23 is supplied from the upper part of the coal feed pipe 24 located in the center of the mill housing 34 as shown by the arrow to the inside of the coal crushing section 25 as shown by the arrow. As described above, the coal crushing section 25 includes a lower ring 30 that rotates at a stationary position connected to the power transmission section 26, and a plurality of balls 3 that revolve and rotate on the lower ring 30.
1 and a fixed upper ring 29 which is pressurized by a nitrogen gas compression cylinder 28.

The supplied coal 23 is passed through the crushing section 25 to the lower ring 30 and the pole 3.
1 and discharged to the outside of the crushing part 25 as shown by the arrow, and the hot air 37 supplied around the lower ring 30 through the hot air pipe 21 causes the crushed coal powder to be pulverized into the mill housing 34 as shown by the arrow. The coal is blown upwards and sent into a classifier 27 that separates it into pulverized coal and coarse pulverized coal as shown by the arrow. The coal powder sent into the classifier 27 is separated into pulverized coal and coarse pulverized coal, and the pulverized coal is passed from the classifier 27 to the outside of the coal feed pipe 24 as shown by the arrow, and from the pulverized coal outlet pipe 32 to the burner section. Then, the coarse pulverized coal is circulated through the coarse pulverized coal discharge port 36 below the classifier 27 to the inside of the coal crushing section 25 again as shown by the arrow, and is pulverized again as shown by the arrow.

Note that foreign substances such as metals and rocks contained in the coal cannot be completely crushed even after passing through the coal crushing section 25, so they fall out of the mill housing 34 from the foreign substance discharge port 33, and are separated and discharged. The pulverized coal crushed in the coal crushing section 25 is released into hot air 37.
It is transported to the burner of the boiler equipment by
Meanwhile, the pulverized coal is dried.

As shown in FIG. 1, the pulverized coal sent out from the pulverizer 5 has a flow rate adjusted by a cut-off damper 6, and is supplied to each burner 8 in the wind box 16 through the entire pulverized coal pipe 7. 1st
In the figure, 11 is a combustion air duct, 15 is a combustion heating air damper, 17 is a flue, and 18 is a furnace.

Next, the structure of the burner 8 will be explained with reference to FIG.

The burner 8 includes a pulverized coal supply nozzle 38 that injects a mixed fluid of pulverized coal and primary air into the furnace 18, and an outer cylinder 39 that surrounds the outer periphery of the pulverized coal supply nozzle 38 and supplies a secondary air pipe. ing. The pulverized coal supply nozzle 38 is arranged from the wind box 16 toward the burner boat 40. The wind box 16 is connected to a secondary air passage 41 and a tertiary air passage 42 by an outer cylinder 39.
A secondary vane 43 and a secondary damper 44t-1 are provided in the secondary air passage 41, and a tertiary damper 45 is provided in the tertiary air passage 42 to control the amount of combustion air.

Note that 46 is a venturi that increases the discharge speed of the mixed fluid in the pulverized coal supply nozzle 38, 47 is a heavy oil burner, and 48 is an ignition burner.

The mixed fluid of pulverized coal and primary air is supplied to the pulverized coal supply nozzle 38
The secondary air is injected into the furnace 18, while the secondary air is given a swirling force by the secondary vane 43 in the secondary air passage 41 and supplied into the furnace 18, and is ignited by the ignition burner 4 and 8, creating a combustion flame. 49 becomes 0 In a combustion device configured like this that uses pulverized coal as fuel, since the pulverized coal fuel is transported to the burner using secondary air, (1) Backfire from the pulverized coal burner may occur. In order to prevent this, the primary air flow rate must be such that the flow velocity of the pulverized coal pipe and pulverized coal supply nozzle can be maintained above the flame propagation velocity (see Figure 4). The coal concentration relative to the air must always be such that self-combustion can occur (see Figure 5).
.

(3) There should be no adverse effects such as sedimentation during transportation of the pulverized coal, which reduces transportation efficiency, or conversely, conversely, the speed of the pulverized coal is too high, causing significant wear on the transportation pipes.

The following conditions are necessary, and each of these conditions will be specifically explained below.

Figure 4 is a characteristic diagram showing the relationship between the amount of pulverized coal/the amount of air and the flame propagation speed for various types of pulverized coal, where VM attached to the flame propagation speed curve is the volatile content, and A is the ash content. The rates are shown for each.

Therefore, it is necessary to adjust the primary air flow rate so that the flow rate of the pulverized coal in the pulverized coal pipe and the pulverized coal supply nozzle is faster than that shown in the flame propagation velocity curve in FIG.

Figure 5 is a characteristic diagram showing the relationship between the amount of pulverized coal/the amount of air and the fuel property coefficient, where the fuel property coefficient shows the ratio of volatile content to the total weight of volatile content and fixed carbon in pulverized coal. . In this figure, zone H indicates a stable combustion region, zone B indicates a non-flame region, and zone C indicates a cross zone between the stable combustion region and the non-flame region]2. As is clear from this figure, for example, when using pulverized coal with a fuel property coefficient of 0.5, the ratio of the amount of pulverized coal to the amount of -water and air needs to be 0.3 or more.

In order to prevent sedimentation of the pulverized coal during transportation and to minimize wear on transport pipes, etc., the flow velocity of the pulverized coal is preferably about 10 to 30 m/sec based on various experimental results.

This fine powder9. In a combustion device that uses fuel as fuel, its control range is at most 40 to 50 inches when the nominal capacity of the crusher is t-10 (1 (rated load)), and the control range is smaller than that of other combustion devices. In other words, as mentioned above, this type of combustion equipment has a system in which the pulverizer is directly connected to the burner and the pulverized coal produced by the pulverizer is immediately supplied to the burner. If the load is lowered too much, the amount of coal supplied will decrease, resulting in direct pressure contact between the lower ring 30 and the ball 31 (see Figure 2), so when using a crusher, the minimum load should be set as described above. Figure 6 shows the load control range of conventional combustion equipment of this type, and the minimum load of the crusher in this case is 50%. In the straight line, there are two crusher tubes, and in the straight line E, there are three crusher tubes.
Straight line F indicates the control range when four units are activated, and straight line G indicates the control range when five units are activated. As shown in this figure, when lowering the boiler load, the number of KFi and crusher operations was reduced.

An object of the present invention is to reduce oil consumption in an auxiliary burner such as an ignition burner, and to provide a combustion device particularly suitable for medium-load coal-fired power generation.

To achieve this objective, the present invention provides: - A coal crusher is provided in the middle of the underwater air supply path, and the pulverized coal produced thereby is directly supplied to the pulverized coal burner together with the primary air, and the pulverized coal is supplied with auxiliary combustion by the auxiliary burner. In a pulverized coal-fired combustion device where combustion is started, a pulverized coal supply amount detection means detects the supply amount of pulverized coal, a primary air supply amount detection means detects the supply amount of air in water, and self-combustion is possible. Coal amount/- Actual coal amount detected by the pulverized coal supply amount detection means and the primary air supply amount detection means by setting the primary air amount specified value/
-Primary air amount Comparing the above-specified coal amount/-primary air amount,
A burner point extinguishing command section that outputs an ignition command for the auxiliary burner when the actual measured value exceeds a specified value and outputs an ignition command for the auxiliary burner, and outputs an extinguishing command for the auxiliary burner when it determines that self-combustion is possible when the actual measured value exceeds the specified value n6. It is characterized by having the following.

The 1/g7 diagram shows the relationship between the 1 self-combustion area and the ignition burner support area. Line H in the figure is the coal input characteristic, line I
indicate the primary air quantity characteristics, zone J indicates the self-combustion region, and zone J indicates the ignition support tube.

With conventional combustion devices, there was little need for detailed control41! The lower limit of the control range was given up at the 40-50 inch load, which was the limit of the self-combustion region (Zone J). However, this figure shows that with the support of the ignition valve, it is possible to lower the lower limit of the control range to 20 inches.

FIG. 8 is a block diagram for explaining the present invention in detail. In order to perform burner lighting/extinguishing control, the amount of coal, the amount of water in the water, and the flame state of pulverized coal are detected by the coal amount detector 50 attached to the coal feeder 3. The amount of primary air supplied to the crusher 8Vc (via the crusher 8Vc) is measured by a primary air flow meter 51 provided between the crusher inlet pump 22 and the crusher 5. The amount of coal and the amount of primary air detected in this way are divided by a divider 52 and converted into a coefficient, and the current value of coal/air is determined in advance by a coal/air comparator 53. A comparative judgment is made as to whether or not the value exceeds the specified value. It is detected by the flame detector 55. That is, in order to monitor the burner flame, determination is made based on a catch frame obtained by a flame detector, and if the output value of the detector is equal to or higher than a predetermined reference value, it is determined that the flame is in a stable state.

As shown in FIG. 1, the mill differential pressure is measured by a pressure gauge 56 on the mill inlet side attached to the hot air pipe 21 near the crusher 5, and a pressure on the mill outlet side attached to the pulverized coal pipe 7 near the crusher 5. It is determined by the difference between the detected value and the total of 57. On the other hand, the -water-air differential pressure is the detected value between the pressure gauge 58 on the ventilator outlet side provided at the outlet @π of the -order ventilator 9 and the pressure gauge 59 on the burner inlet side provided on the inlet side of the burner 8. The mill differential pressure and primary air differential pressure thus detected are divided by a divider 60 and converted into a coefficient, and the mill load rate determiner 61 determines the current mill load rate. A determination is made as to whether or not the mill load factor is equal to or higher than a predetermined mill load factor regulation value.

As a combustion device, the ignition burner is first ignited based on the ignition burner ignition command, and after ignition is confirmed, the pulverized coal burner ignition waste is output. The coal feeder, the pulverizer, and the pulverizer are started, and combustion takes place in the pulverized coal burner.As the boiler load increases, the pulverizer load also increases.
The ventilator activation signal, the coal feeder activation signal, and the crusher activation signal are each input to the burner point extinguishing determination device 62 to confirm combustion. On the other hand, the coal/air comparator 5
3, the determination result by the flame determination device 55, the determination result by the mill load factor determination device 61, etc. are also input to the burner point extinguishing determination device 62, respectively. Then, if ■ combustion is confirmed, ■ actual coal amount/-secondary air amount is greater than the specified value, ■ burner flame is stable, and ■ actual mill load factor is greater than the specified value, then these four When these two conditions are met, it is determined that the combustion conditions have reached the self-combustion range, and the ignition burner is extinguished in response to a command from the control unit (not shown), and the load on the boiler is controlled by igniting only the pulverized coal burner. On the other hand, if even one of the four conditions is not met, it is determined that the condition is not satisfied, the ignition burner and the pulverized coal burner are ignited as they are, and the load of the boiler is controlled in this state.

The coal amount/secondary air amount burner flame, mill load rate and combustion rod wl are intermittently detected at short intervals,
Each time, a determination is made as to whether the four conditions are met or not.

As described above, the present invention constantly monitors the coal amount/secondary air amount flame condition and crusher load rate, and provides immediate assistance when it is determined that both of these conditions are satisfied and the self-combustion region has been reached. Since the burner is extinguished and load control is performed only by the pulverized coal burner, the auxiliary burner can be extinguished quickly and the consumption of petroleum etc. can be reduced thereby, making it very economical.

In addition, the load control range is expanded, making it particularly suitable for medium-load coal-fired power generation.

In addition, although the above embodiment describes the case when the pulverized coal burner is ignited, the present invention is not limited to this. When the combustion conditions are outside the self-combustion range, it is determined by constantly monitoring the coal amount/secondary air amount flame condition and the crusher load factor, and based on the determination result. An auxiliary burner can be ignited.

[Brief explanation of drawings]

Figure 1 is a schematic configuration diagram of a pulverized coal-fired boiler equipment, Figure 2 is a schematic diagram of a coal crusher attached to the boiler equipment,
Figure 3 is an enlarged sectional view of the vicinity of the burner section of the boiler equipment.
Figure 4 is a characteristic diagram of the relationship between the amount of pulverized coal/-the amount of air in the air and the flame propagation speed, Figure 5 is the characteristic diagram of the relationship between the amount of pulverized coal/-the amount of air in the air and the fuel property coefficient, and Figure 6 is the characteristic diagram of the relationship between the amount of pulverized coal and the fuel property coefficient. A characteristic diagram of the relationship between the boiler load and the crusher load rate in the boiler device, FIG. 7 is a characteristic diagram of the relationship between the crusher load rate, the primary air amount rate, and the coal input rate, and FIG. 8 is a diagram according to an embodiment of the present invention. FIG. 2 is a block diagram for explaining a burner ignition control method. 5...Crusher, 7...Pulverized coal pipe, 8.
...Burner, 13...Heating air duct,
14...Cold air duct, 21...Hot air pipe, 23...Coal, 47...Heavy oil burner, 48...Ignition burner , 50・'...
・Coal amount detector, 51...-Underwater airflow meter, 5
3...Coal/air comparator, 54...Flame detector, 55...Flame determiner, 56...
... Mill inlet side pressure gauge, 57... Mill outlet side pressure gauge, 58... Ventilator outlet side pressure needle, 59...
. . . Burner inlet side pressure gauge, 61 . . . Burner load factor determination device, 62 . . . Burner point extinguishing determination device. Agent Patent Attorney Kenjibu Takeshi 74 Showa et al.

Claims (1)

[Claims] (1) A coal pulverizer is provided in the middle of the primary air supply route, and the pulverized coal produced by the pulverizer is mixed with the primary air and K[! In a pulverized coal-fired combustion device in which pulverized coal is supplied to an IK pulverized coal burner and combustion is started with auxiliary combustion from an auxiliary burner, a pulverized coal supply amount detection means detects the amount of pulverized coal supplied, and a pulverized coal supply amount detection means detects the amount of secondary air supplied. The actual amount of coal detected by the primary air supply amount detection means and the primary air supply amount detection means and the primary air supply amount detection means is set by setting the specified value of surface coal amount/-secondary air amount that can self-combust. Compare the primary air volume with the stipulated stone leg volume/-primary air volume pipe, and if the actual value does not exceed the stipulated value, the actual value of the ignition command pipe 1 of the auxiliary burner exceeds the stipulated value. A burner point extinguishing control device comprising: a burner point extinguishing command section that determines that self-combustion is possible and outputs an extinguishing command for each of the auxiliary burners. (2) In addition to the pulverized coal supply amount detection means and the primary air supply amount detection means, a large flame detection means for the pulverized coal burner is provided, and the burner point extinguishing command is provided. In addition to the specified value of coal amount/-primary air amount, a flame state coefficient that allows self-combustion is specified in the part, and is detected by the pulverized coal supply amount detection means, the primary air supply amount detection means, and the flame detection means. The actual measured value is compared with the prescribed value set in the burner point extinguishing command unit, and if at least one of the actual measured values exceeds the prescribed value, the employee and the assistant...
- A burner point extinguishing control device characterized in that when all actual measured values of the burner ignition command exceed specified values, extinguishing commands for the stones and the auxiliary burner are output from a burner point extinguishing command unit. (3), Claim @ In the statement in (1), a crusher load factor detection means is provided in addition to the pulverized coal supply amount detection means and the primary air supply amount detection means, and the burner point extinguishing command section is provided with a crusher load factor detection means. In addition to the specified value of coal amount/-primary air volume, the crusher load is specified, and the actual measurement detected from the pulverized coal supply amount detection means, primary air supply amount detection means, crusher load car detection and stage. The value is compared with the specified value set in the burner ignition extinguishing command unit, and if at least one of the actual measured values does not exceed the specified value, the auxiliary burner ignition command is set to all the measured values. A burner point extinguishing control device characterized in that a burner point extinguishing command unit issues an extinguishing command for an auxiliary burner when the value exceeds a specified value.