JPS58205019A - Combustion controller for coal - Google Patents

Abstract

PURPOSE:To uniform the thermal absorption in a furnace and make it possible to reliably control the combustion state of each of burners, by providing a flow rate controller which regulates the amount of air supplied to each burner corresponding to each mill. CONSTITUTION:Coal is fed to a mill 5 by a coal feeder 3 while being regulated in the flow rate. The coal ground in the mill 5 is supplied to a multiplicity of burner 7 through pulverized-coal pipes 6 and burnt therein. On the other hand, the air for combustion is divided into a primary air 11 and a secondary air 12. The secondary air 12 is heated by a heater 13 and then injected into the furnace from wind boxes 22 through ducts 20. On the other hand, the primary air 11 is heated by the heater 13 and supplied being boosted up by a primary air fan 10. Dampers 15, 18, 17, 21 are provided on air supply lines, respectively, thereby allowing an individual regulation of the flow rate of the primary and secondary air with respect to the burner group for each mill 5, in addition to an overall flow rate regulation.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a combustion control device for coal, and particularly to a combustion control device for a boiler device or the like suitable for reducing unburned matter and nitrogen oxides in exhaust gas.

The pulverized coal floating combustion method, which is currently out of mainstream in coal-fired boilers, requires large capacity equipment, boiler operation,
From the viewpoint of operability, etc., the mill and burner are often constructed from a large number of units. Particularly when the boiler equipment is large, it is important to determine the specifications of the mill, the combustion equipment, etc. based on the economic efficiency of the plant equipment costs, operating costs, etc., and the location conditions.Basically, the operability of the boiler is The quantity and arrangement of mills and burners are determined with emphasis.

In such a large boiler device, the amount of coal fed to each mill is not completely the same, and the amount of coal fed changes from one mill to another with time. For example, at a certain time, sA's mill has a slightly higher coal flow rate than &B's mill, but at the next time, some time later, sBO has a higher coal flow rate than mA (2). In this case, only the controlled total amount of combustion air is supplied to the burners corresponding to each mill at each time, and the amount of coal and air to each burner group do not necessarily match to produce the best results. . In addition, if a separate hopper is provided for each mill and different types of coal are supplied, each mill will pulverize coal with a different calorific value (effective coal content) per unit weight and send it to the burner. will be supplied. As a result, it was found that the adjustment of the amount of air for each burner group was incomplete and that there was a problem in improving combustibility, including unburned matter and NOx generation for each burner.

An object of the present invention is to provide a combustion control device that can improve the drawbacks of the prior art described above, make the heat absorption in the furnace uniform, and reliably control the combustion state according to each burner. be.

The present invention is installed in the furnace during winter! Coal combustion control (3) apparatus comprising: a fuel supply system that supplies pulverized coal together with primary air from a plurality of mills to several burners; and an air supply system that supplies secondary air for combustion into the furnace; The present invention is characterized in that a flow rate control means is provided for adjusting the amount of air supplied to the burner for each burner corresponding to each mill.

Preferably, the flow rate control means in the present invention adjusts the combustion air flow rate in accordance with the amount of coal supplied to the burner for each mill.

The present invention also includes a measuring device that continuously measures the calorific value, combustible elements, and other properties of the coal supplied to each mill for each mill, and a measuring device that continuously measures the properties such as the calorific value and combustible elements of the coal supplied to the burner, and the optimum amount of combustion for the burner in accordance with the measured values. Preferably, an air flow rate control device for supplying air is provided.

Hereinafter, the present invention will be explained in more detail with reference to the drawings.

FIG. 1 is a system diagram of a pulverized coal combustion apparatus showing one embodiment of the present invention. In this embodiment, for convenience, three mills are shown, but in the present invention, the number of mills, the number of burner phases, the number of burners, etc. are not particularly limited. The coal stored in the coal bunker passes through the coal feeding pipe 2 and is fed to the mill 5 while the flow rate is adjusted by the coal feeding machine. Normally, the flow rate of coal (4) is controlled by detecting the flow rate with a flow meter 4 attached to the coal feeder 3 so that the detected value becomes the amount required for heat input to the boiler. Coal pulverized in the mill 5 is supplied to a number of burners through pulverized coal pipes 6 and burned in the furnace. Here, the burner arrangement is usually
Because the coal emitted from the boiler furnace 8 absorbs uniform heat,
Preferably, the burners are fed to the same level of burners in the horizontal direction as shown. As a result, regardless of the number of mills in operation, heat absorption within the furnace is always uniform, and steam generation characteristics and steam temperature controllability are maintained in good condition.

Note that 14 is an exhaust gas line.

On the other hand, air for combustion is separated from a forced fan 9 into primary air 11 for coal drying/transporting and secondary air 12, and the secondary air]-2 is heated by an air heater 13 and then passed through a duct 2.
0, and enters the burner wind box 22 through the damper 21 and the like. The air injected into the furnace from the wind box 22 and the pulverized coal supplied together with the primary air are mixed and combustion is performed. The secondary air 11 is heated by an air heater 13 in the same way as the secondary air 12, and is supplied to each (5) mill 5. Normally, the differential pressure of the system needs to be higher for the secondary air than for the secondary air, so the air heater 13
A primary air fan 10 installed upstream or downstream of
It is boosted up and supplied. Note that a line for introducing cold air bypassing the air heater 13 into the mill inlet can be provided for temperature adjustment of the secondary air.

- The flow rate adjustment of the primary and secondary air is basically performed using the primary and secondary flow meters 16 and 19 installed in the main pipe on the upstream side and downstream side of the air heater 13, and - the primary and secondary air flow rate adjustment. This is done by dampers 15.18. Among these, the flow rate of secondary air is basically a type that feeds back the situation of the concentration in the boiler exhaust gas, and is used to control the total amount of air supplied to the burner groups at each stage. In the present invention, in addition to the above-mentioned comprehensive flow rate adjustment of the primary air and secondary air, dampers 17 are installed in the primary air 11 lines of each mill 5, respectively.
In addition, a damper 21 is provided in each secondary air supply line to the wind box 22 at each stage, and each flow rate of primary and secondary (6) air to the burner group can be adjusted individually corresponding to each valve 5. There is.

According to the above embodiment, by making it possible to control the flow rate of primary and secondary air for each burner group corresponding to each mill, the amount of coal supplied to each mill and the type or calorific value of the supplied coal can be controlled. You can control the air pump appropriately in response to this. Particularly when changing the air-fuel ratio of each stage burner to achieve low NOx combustion, accurate air-fuel ratio control is required for each stage burner. Since the fuel ratio is controlled, it is ensured that low N
It is possible to reduce O, and unburned content.

In the above embodiment, the wind box of the burner stage corresponding to each mill may not be separated from other burner stages, but as shown in Fig. Improved combustion conditions by adjusting air amount for each stage, low N
It is preferable to divide the wind box 22 into each burner group in order to reduce the temperature.

Next, FIG. 2 shows another embodiment of the present invention, in which the coal and air flow path system and component equipment are basically the same as in FIG. ) An air flow meter 23 and a flow rate adjustment damper 21a are installed for each burner group in the secondary air system supplied to the mill, and the flow rate transmitted by the secondary air flow meter 23 for each burner group corresponding to this mill is measured. The signal, the coal feeding amount signal output from the coal feeding flowmeter daytime, and the calorific value or elemental analysis value signal from the coal continuous analyzer 27 attached to the coal feeding system are sent to the receiving calculator 25, where this coal The optimal amount of air for combustion is calculated and converted into a control signal, and then the command transmitter 26 uses this signal to adjust the opening degree of the secondary air artificial damper 21a of the burner group corresponding to this mill, and the air flow rate is adjusted. It is designed to control the

By adopting the control method using the above means, the correlation between the amount or (and) properties of coal fed into the mill and flowing to the burner and the secondary combustion air flow rate is maintained, and the coal flow rate between mills and Regardless of differences in coal properties such as calorific value and composition, it is possible to control the optimal combustion air flow rate for the combustion of coal emitted from each mill. As a result, even if there is an imbalance of stones (8) and charcoal between these mills, good combustion conditions are ensured for each burner. In other words, the combustion air for each burner is controlled in such a way that the flow rate and combustion air of the coal supplied to each burner changes accordingly, so that the combustion of each burner is always maintained at its optimum condition. It is possible. Furthermore, as a result, (1) a reduction in the minimum load of each burner due to stable combustion, (2) a reduction in unburned content due to good combustion,
Reducing the amount of CO generated and (3) equalizing the combustion characteristics of each burner, resulting in NO burner part! (4) Reducing the amount of air and coal consumption by controlling the amount of air that is necessary and sufficient, and saving energy. Although a structure is shown in which the corresponding burners are arranged horizontally on the wall surface of the furnace, the burners may be arranged at the corners of the furnace or vertically. Further, in the above embodiment, the air amount corresponding to the burner group supplied from the same mill is controlled, but it is also possible to further control the air flow rate corresponding to each burner.

In this case, the combustion control of each burner becomes more complete (9), and it is expected that the effects described above will be further improved.

As described above, according to the present invention, the amount of coal fed to the mill (and) the flow rate of combustion air for each mill (
or air-fuel ratio), (1) burner,
Effects such as reduction in mill minimum load operation, (2) reduction in unburned matter and CO production, (3) reduction in NOx production, and (4) energy saving by reducing excess air can be obtained.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are system diagrams of a pulverized coal combustion boiler showing one embodiment of the present invention, respectively. l...Coal banca?・−・Coal feed pipe, 3・
...Coal feeding machine, 4...Coal feeding flow meter, 5...
... Mil, 7... Burner, 8...
Furnace, 11...-Secondary air, 12...Secondary air, 15...-Secondary air flow rate adjustment damper, 1
6...-Primary air flow meter, 17...Mil-filled low-order air 7 C, 1 f3...Secondary air flow rate adjustment damper, 19...2 Secondary air flow meter, 20...Secondary air system box duct, 21% 21
a... Secondary air winter melon boxed Rodan (10) Pa, 22... Wind box, 23... Secondary air winter melon boxed flow meter, 25... ...Receiver/calculator, 26
・・・・・・Command transmitter. Agent Patent Attorney Takeshi Kawakita °・1・ (11)

Claims (1)

[Claims] (1) A fuel supply system that supplies pulverized coal from a plurality of mills together with primary air to a plurality of burners provided in a furnace; and an air supply system that supplies secondary air for combustion into the furnace. What is claimed is: 1. A coal combustion control device having a supply system, the coal combustion control device comprising a flow rate control means for adjusting the amount of air supplied to the burner for each burner corresponding to each mill. (2. A coal combustion control device according to claim 1, characterized in that a flow rate control means is provided for adjusting the combustion air flow rate in accordance with the amount of coal supplied to the burner for each mill. (3) In claim 1 or 2, there is provided a measuring device that continuously measures properties such as the calorific value and combustible elements of the coal supplied to each mill for each mill, and corresponds to the measured values. (1) A coal fuel control device comprising: (1) an air flow rate control device for supplying an optimum amount of combustion air to the burner;