JPS6026263Y2 - Combustion safety device for fluidized bed incinerator - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a combustion safety device suitable for checking ignition of a crushing burner, etc. in a fluidized bed incinerator plant.

FIG. 1 shows a combustion system diagram of commonly used combustion equipment.

This equipment has a main burner 2 and a pilot burner 3 facing into a combustion chamber 1, and is further equipped with an ignition device 4 adjacent to the pilot burner 3.

Fuel supply pipes 5, 6 are connected to both burners 2, 3, and a pilot cutoff valve 8 and a main burner cutoff valve 7 are interposed in the supply pipes 6, 5.

For combustion, the pilot burner 3 is ignited by the ignition device 4,
This is done by using this as a spark to ignite the main burner 2.

The installation is equipped with a combustion safety device, which includes a flame detector 11 that monitors the pilot flame 9 and the main burner flame 10.
and the shutoff valve 7, depending on the output signal from the sensor 11,
8 and a control section 12 that outputs a closing signal.

On the other hand, the combustion chamber 1 includes the main burner 2, the pilot 3,
A ventilation passage 13 is provided which opens at the mounting portion of the ignition device 4 and the flame sensor 11, and a damper 14 is attached to this ventilation passage 13.

The ventilation passage 13 introduces the air supplied from the ventilation passage 15 into the combustion chamber 1 .

Further, a flue 16 is opened in the combustion chamber 1.

As described above, the operation of the combustion safety device of the combustion equipment is performed as follows according to the chart shown in FIG.

First, the damper 14 is opened and the ventilator 15 is operated, thereby purging the combustion chamber 1 and the flue 16 and exhausting the combustible gas remaining inside.

Next, the pilot cutoff valve 8 is opened by the ignition command, ignition fuel is supplied to the pilot burner 3, and the pilot burner 3 is ignited by the ignition device 4.

A flame sensor 11 monitors whether ignition occurs and a viroft flame 9 is emitted, and if the flame 9 is not emitted, it is determined that a pilot misfire has occurred, and the signal is input to a safety device control section 12.

Then, in response to a command from the safety device control section 12, the pilot shutoff valve 8 is closed, the supply of ignition fuel is stopped, and the above-mentioned purge operation is restarted.

On the other hand, when the pilot flame 9 is coming out, the main burner cutoff valve 7 is opened, main burner fuel is supplied to the main burner 2 and ignited, and then the pilot burner 3 is extinguished.

A flame sensor 11 monitors whether or not a main burner flame is emitted from the main burner 2, and when a flame 10 is not emitted, it is determined that the main burner has misfired, and the signal thereof is input to a safety control section 12.

Then, in response to a command from the safety control section 12, the main burner cutoff valve 7 is closed, the supply of main burner fuel is stopped, and the above-mentioned purge is restarted.

On the other hand, if the main burner flame 10 is coming out, it is determined that combustion is normal, and combustion operation continues.

However, in the case of a crushing burner used in a fluidized bed type incinerator as shown in FIG. 3, the flame cannot be monitored by the flame detector 11 because fuel is injected into the fluidized bed (while crushing).

That is, in the fluidized bed incinerator 17, there is a fluidized bed (sand) inside.
18, and the injection nozzle 2 of the crushing burner 19 is filled therein.
0, and the air-fuel mixture supplied from the air and fuel supply pipes 21, 22 is injected and combusted during crushing.

Therefore, unlike the combustion burner shown in FIG.
It is impossible to confirm (detect) ignition by checking and monitoring the presence or absence of flame.

As described above, fluidized bed incinerators have the problem of not being able to confirm ignition by flame monitoring, and a safety device that can confirm combustion of the crushing burner has been desired.

The present invention focuses on the above conventional problems and aims to provide a combustion safety device for a fluidized bed incinerator that can detect ignition of a burner during crushing of a fluidized bed.

In order to achieve the above object, the combustion safety device for a fluidized bed incinerator according to the present invention is provided with a temperature detector inserted into the fluidized bed to detect the temperature of the fluidized bed, and a detection signal of the temperature detector is inputted. A temperature comparator that compares the temperature with a specified temperature, and a timer that counts a specified time.The controller outputs a valve closing signal if the detected temperature does not reach the specified temperature after the specified time has elapsed. In addition, a cutoff valve that is closed by an output signal from the controller is interposed in at least the fuel pipe of the combustion burner.

With this configuration, the fact that the temperature of the fluidized bed increases due to ignition is utilized, and ignition is confirmed based on this temperature.

This makes it possible to confirm combustion in fluidized bed incinerators where flame cannot be monitored, and enables safe operation.

Embodiments of the combustion safety device for a fluidized bed incinerator according to the present invention will be described in detail below with reference to the drawings.

FIG. 4 shows a sectional view of the fluidized bed incinerator provided in the combustion safety device of this embodiment.

As shown in this figure, the fluidized bed incinerator 30 has a perforated plate 31 that partitions the interior into upper and lower parts, and the upper chamber thereof is filled with a fluidized bed 32 to be incinerated.

The crushing burner 33 as a means for incinerating the fluidized bed 32 is
It is composed of a pipe 34 surrounding the incinerator 30 and an injection nozzle 35 inserted into the fluidized bed 32 from the pipe 34.

The injection nozzles 35 are arranged in multiple stages in the circumferential direction of the incinerator 30 as in the case shown in FIG. There is.

A fuel pipe 36 for supplying fuel and an air pipe 37 for supplying compressed air are connected to such a crushing burner 33 to inject fuel at an optimum air-fuel ratio.

Both of these pipes 36 and 37 are provided with cutoff valves 38 and 39 that can stop the supply of fuel and air.

Such a fuel system includes, as a combustion safety device, a temperature detector 40 that detects the temperature within the fluidized bed 32, and a controller 41 that inputs a signal from this detector 40.

The temperature detector 40 is made of a thermocup and converts the temperature of the fluidized bed 32 into an electrical signal and outputs it.

Further, a controller 41 that inputs the signal of this temperature detector 40
As shown on the chart in FIG. 5, the apparatus has an ignition temperature comparator 42 for checking whether the fluidized bed 32 is at a combustible temperature (650° C. or higher in the embodiment).

The circuit is configured to give a valve opening signal to the fuel cutoff valve 38 based on the output signal of the comparator 42, and opens the cutoff valve 38 when the combustion temperature is reached and sends the crushing burner 33 to the fuel cutoff valve 38.
to provide fuel.

The controller 41 also includes a timer 43 that is excited by the opening signal of the fuel cutoff valve 38 and counts a specified time.
and a combustion temperature comparator 44 that compares the temperature detected by the temperature detector 40 with a preset specified temperature.

The timer 43 is based on the premise that the temperature of the fluidized bed 32 will rise after a certain period of time has passed since the fuel is supplied to the incinerator 30 and the temperature of the fluidized bed 32 will rise. It is something to do.

This specified time is set to 7 minutes in the embodiment.

Further, the combustion temperature comparator 44 sets a temperature that would rise if the combustion is in progress after the time counted by the timer 43 has elapsed, and compares this specified temperature with the actual detected temperature. It is.

In the example, the specified temperature is 700°C.

Further, a discriminator 46 is provided on the output side of the timer 43 and the combustion temperature comparator 44, and if the fluidized bed 32 does not reach a specified temperature within a specified time, a valve closing signal is sent to the fuel cutoff valve 38. The feedback circuit 47 then compares and detects the ignition temperature.

The operation of the combustion safety device thus constructed is performed as follows based on the chart of FIG.

That is, first, the compressed air cutoff valve 39 is opened, and compressed air is injected from the injection nozzle 35.

Next, a temperature detector 40 installed in the crusher detects whether or not the fluidized bed 32 is at a combustible temperature, and a comparator 42 confirms that the temperature is higher than the combustible temperature, and the fuel is shut off. A valve opening signal is given to the valve 38.

As a result, fuel is injected from the nozzle 35 into the fluidized bed 32 along with the compressed air.

Fuel i! ! When the valve 38 opens, a signal is output to the safety control unit 45, and the timer 43 starts counting a specified time based on the signal.

After the specified time has elapsed, the comparator 44 checks whether the temperature within the fluidized bed 32 is higher than the specified temperature, and if the temperature is higher than the specified temperature, the operation continues.

On the other hand, if the temperature does not reach the specified value within the specified time,
Since the fuel is being injected without igniting, it is determined that a misfire has occurred, and a valve closing signal is given to the fuel cutoff valve 38 to stop the fuel supply, and at the same time, a misfire alarm etc. is issued.

Then, the operation resumes from the detection of the ignition temperature.

In this manner, in this embodiment, the ignition state of the fuel can be safely and reliably confirmed in the fluidized bed incinerator 30 in which fuel ignition cannot be confirmed by flame monitoring.

FIG. 6 shows a safety control section 451 in another embodiment.

In this embodiment, the specified time of the timer 43 is set in correspondence with the fuel flow rate Q, and the ignition state can be confirmed more effectively by taking into account the delay in the operation of the temperature detector 40.

The time required for combustion by fuel injection in the fluidized bed 32 in the combustion equipment and for the temperature in the fluidized bed 32 to reach a specified value varies depending on the fluidization state of the fluidized bed 32, the size of the furnace 30, the amount of air, etc. Moreover, it varies depending on the supplied fuel flow rate.

Therefore, the safety control unit 451 is provided with a calculator 48 for calculating the dynamic characteristics from fuel combustion until the temperature reaches the specified value, and the timer 4 is added to the calculated timer set amount.
I am trying to set it to 3.

This specific calculation process is based on the following formula.

T=KXQ...(1)
Here, T is the timer set amount, K is a constant determined from the size of the furnace, the amount of air, etc., and Q is the fuel flow rate.

In this case, the dynamic characteristics involve various elements and cannot be calculated in practice. Therefore, the fuel flow rate Q, which is a major variable factor, is determined experimentally by factors such as stiffness and other factors, and then processed as a constant. shall be.

In addition, the safety control unit 451 includes a calculator that calculates the time constant of the temperature detector 40 and adds the response delay of the detector 40 to the time constant of the temperature detector 40.
A specific number calculator 49 is provided.

This eliminates the possibility of erroneously recording ignition confirmation due to a response delay of the temperature detector 40.

According to the second embodiment, the combustion temperature, which varies in proportion to the fuel flow rate Q, can be accurately grasped, and uncertain factors in ignition confirmation due to the response delay of the detector 40 can be eliminated. Setting values can be freely changed more efficiently and effectively, making it possible to provide a highly flexible safety device.

In the embodiment, the temperature detector 40 is not limited to a thermocup, but may be any other detection means as long as it can detect the temperature and electrically convert the detected value.

As explained above, according to the present invention, it is possible to safely and reliably detect the ignition of the parner in the sand, which is an excellent effect.

[Brief explanation of the drawing]

Fig. 1 is a combustion system diagram of a general combustion equipment, Fig. 2 is an operation flowchart of the equipment, Fig. 3 is a plan view of a conventional fluidized bed incinerator, and Fig. 4 is a combustion safety according to this example. FIG. 5 is a sectional view of a fluidized bed incinerator equipped with the apparatus, FIG. 5 is an operation flowchart of the apparatus, and FIG. 6 is an operation flowchart of the main parts of a combustion safety apparatus according to another embodiment. 30...Fluidized bed incinerator, 32...Fluidized bed, 33...Crushing burner, 38...Fuel cutoff valve, 39...・Compressed air shutoff valve, 40...
... Temperature detector, 41 ... Control section, 43.
...Timer, 44... Combustion temperature comparator,
45...Safety control section.

Claims (2)

[Scope of utility model registration request] (1) In a combustion safety device used in a fluidized bed incinerator, which is equipped with a burner that injects fuel into the fluidized bed, and fuel piping and air piping that supply fuel and compressed air to the burner, It has a temperature detector that is inserted to detect the temperature of the fluidized bed, a timer and a temperature comparator that receives the detection signal of this temperature detector and counts a specified time, and the detected temperature does not reach the specified temperature after the specified time has elapsed. Combustion safety for a fluidized bed incinerator, characterized by comprising a controller that sometimes outputs a valve closing signal, and a shutoff valve installed in at least the fuel pipe that is closed by the output signal of the controller. Device. (2) The controller includes a computing unit that computes the combustion dynamic characteristics in the fluidized bed in accordance with the fuel flow rate and sets a timer, and a computing unit that computes the time constant of the temperature detector. A combustion safety device for a fluidized bed incinerator according to claim 1.