JPS6387506A - Layer height indicator of fluidized bed boiler - Google Patents

Abstract

PURPOSE:To facilitate the operation of the boiler by placing a plurality of horizontal pipes in the fluidized bed and a hollow tower part, to make air flows within the tubes uniform and to indicate an outlet temperature on a screen. CONSTITUTION:Air which has passed through a pipeline 8 is supplied to a wind box 2 of the fluidized bed boiler 1, and a fluidizing medium of a porous plate 3 is fluidized to form a fluidized bed 4. Within the bed a heat transfer tube 15 for generating steam and an overheated steam tube group 16 are provided. A branched pipe 8' of the pipeline 8 supplies air from a blower 18 to an upright header 9. One end of each of horizontal pipes 5a-5e is connected to the header 9, and the other end thereof forms an outlet pipe which is provided with valves 6a-6e and flowmeters 14a-14e, and is connected to an outlet pipe header 11. The temperature of air in the outlet pipe is indicated on a screen indicator 13 from temperature transmitters 7a-7e via a control box 12. Since the measurement of the temperature is not conducted using steam but is conducted using air so that even when a measuring pipe is damaged, it does not lower the efficiency of the boiler and also does not cause the stoppage of the boiler.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fluidized bed combustion apparatus, and in particular to a method for controlling the bed height of a fluidized medium related to evaporation amount and steam temperature superheated steam temperature control in a fluidized bed boiler. The present invention relates to a height indicating device suitable for monitoring and controlling.

<Prior art and its problems> As shown in Fig. 4, the fluidized bed height monitoring device of the conventional fluidized bed combustion equipment detects the pressure between the wind box and the outside of the bed, and calculates the fluidized bed height from this pressure difference. I used a calculation method.

However, no consideration was given to the fact that pressure fluctuations are large and accurate pressure differences cannot be obtained, and that the height of the fluidized bed is not uniquely determined only by the multi-layer pressure difference, which varies depending on the specific gravity of the medium.

Additionally, as shown in Figure 5, there is a method of detecting the standard layer pressure within the layer and calculating the layer height from the pressure difference between the lower part of the layer and the outside.
This also did not take into account the fact that the draft seat for pressure detection in the layer would be clogged with media, and that the differential pressure between layers would fluctuate, making it impossible to obtain accurate values. An example of this type of device is JP-A-56-46901 (published on April 28, 1983), which has straight pipes arranged horizontally and in multiple stages, and each pipe contains water and water. The height of the layer is controlled by flowing steam and detecting the temperature at the outlet. However, if this detection tube wears out and breaks, water and steam will be ejected into the layer, making the operation of the boiler etc. unsafe and unstable.

The above-mentioned conventional technology has the following points: the fluidized bed pressure fluctuates rapidly due to the blow-through of the fluidizing pressure gas and the formation of boiling fluid, the fluidic medium clogs the pressure detection tube in the bed, and the bed differential pressure The problem was that the exact height of the layer could not be determined because different points (depending on the specific gravity of the layer) were not specifically arranged.

<Object of the Invention> An object of the present invention is to provide a device that facilitates load control and steam temperature control of a fluidized bed boiler by measuring the correct bed height and displaying the measurement on a screen.

Overview of the means for achieving this> A plurality of tubes are arranged horizontally in the fluidized bed and the empty tower section, the flow rate of the air flowing inside these tubes is made uniform for all six tubes, and the air temperature at the outlet section is displayed on a screen using a cathode ray tube, etc. This makes the boiler easier to operate.

Embodiment FIGS. 1 to 6 are drawings showing the structure of a fluidized bed boiler combustion apparatus according to an embodiment of the present invention.

Pressurized air used for fluidization and combustion is supplied from a blower 18 to the wind box 2 of the fluidized bed boiler 1 through a pipe 8. The fluid medium (sand, etc.) on the perforated plate 3 is p#,
fluidized bed 4 is formed. A heat transfer tube group 15 is provided within the layer, and absorbs heat from combustion of fuel supplied from a fuel supply device (not shown) to generate steam. Also, superheated steam pipe group 16 (normally distributed within the layer like the evaporator tube group)
is also provided within the fluidized bed.

The heat transfer coefficient to the heat transfer tube in the fluidized bed is 200 to 250 Ka.
The heat transfer coefficient in the void space outside the layer is much smaller, about 50 Km/m2-h-°C.

On the other hand, the temperature within the fluidized bed is maintained at approximately 800 to 850°C from the viewpoint of continuing self-combustion of the fuel and preventing the generation of NOx. Therefore, controlling the amount of evaporation and superheated steam temperature by controlling the amount of fuel supplied depends on the increase or decrease in the area of the heat exchanger tubes immersed in the fluidized bed, so the depth of the fluidized bed, that is, the bed height (
Confirming and controlling H) is an important issue.

The bed height of the fluidized bed is controlled by a fluidized medium supplying device and a drawing device (not shown).

In this embodiment, a horizontal pipe 5α is used for layer height detection.

5b, 5c, 5d, 5g (5a'5b'5c'
5d'5a') is an equal level interval S (Fig. 2) (if necessary, the S dimension should be made smaller near the layer surface during rated operation, and the variation should be more arranged. In order to ensure a passage length sufficient for replacement, the tube may be bent into a U shape as shown in the figure.

A pipe 8' branching from the pipe line 8 supplies pressurized air from a blower 18 to an upright header 9.

The - pipe ends of the horizontal pipes 5α to 5e (5α' to 58') are connected to this header 9, and the outlet pipes connected to the other ends are provided with valves 6.
α to 6e and flowmeters 14α to 14g are provided respectively.

This outlet pipe further connects to an outlet header 11.

Before starting the device, in order to equalize the flow velocity of air flowing through the pipes in each horizontal pipe and to make the heat transfer conditions the same, monitor the float in the flow meter that displays the flow velocity in the pipes and adjust the opening degrees of valves 6α to 6e. .

The float 20 is housed in a transparent glass tube 19 whose inner diameter is smaller at the bottom and larger at the top. A small slit 17 is cut diagonally to the axis on the outer circumference of the float, and when gas flows through the glass tube, the float rotates and floats to a stable position according to the flow rate.

When the flowmeters (14α to 14e) are placed at the same level as the float, the opening degree of the valve can be easily adjusted.

In addition, a temperature transmitter (7α to 7g) is attached to each outlet pipe, and the temperature of the air flowing through each outlet pipe is measured, and the temperature is displayed on a screen display device 13 using a cathode ray tube or the like via a control box 12. Display. In this case, as shown in the figure, it is immediately clear that the layer height is located between the horizontal pipes where there is a large difference in air temperature.

Note that the layer temperature and layer height can be controlled by using the position signal corresponding to the layer height H to control the supply and extraction of the medium and the supply amount of fuel and combustion air.

(Effects) By implementing the present invention, (1) Unlike the conventional case of using water or steam, there is no reduction in boiler efficiency due to spouting of boiler water or steam, which occurs when a pipe breaks.

(2) Even if a pipe is damaged, it becomes air, so it only becomes combustion air and does not lead to boiler stoppages.

(3) It is easy to drive because it is displayed on the screen.

(4) It is easy to adjust the air flow rate in the horizontal pipe by arranging flowmeters in parallel.

(5) Problems such as media clogging 9 of the layer height detection device have completely disappeared.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway perspective view of a device showing an embodiment of the present invention, Fig. 2 is a partial cross-sectional view of the device shown in Fig. 1, Fig. 3 is a front view of the rotor type flowmeter, and Fig. 4 , FIG. 5 is a schematic cross-sectional view of a conventional Q layer height measuring device.

Claims (1)

[Claims] 1. Air is supplied to a plurality of horizontal pipes arranged at intervals from the upper surface of the distribution plate in the fluidized bed and the empty column, respectively, and provided on the pipe body discharge side of the horizontal pipes. 1. A bed height indicating device for a fluidized bed combustion apparatus, characterized in that the bed height of the fluidized bed is detected based on the temperature indicated by a thermometer. 2. The fluidized bed according to claim 1, characterized in that each horizontal pipe is provided with a flowmeter, a thermometer is provided at the outlet of the horizontal pipe, and a device is provided for comparing and displaying these measured values. Combustion equipment layer height indicator. 3. The flow velocity of the air in the horizontal pipe is measured by a rotary flow meter provided in each pipe, and the flow rate is controlled by a control valve provided in each pipe. A bed height indicating device for a fluidized bed combustion apparatus according to item 1.