JPS63243622A - Method of semi-continuous operation of fluidized bed incinerator having boiler - Google Patents

Abstract

PURPOSE:To enable an incinerator to be semi-continuously operated at the time when the incinerator for city refuse is intermittently by maintaining the boiler pressure at a level closer to that which exists under normal operating conditions while the furnace is being suspended by making use of a heat transfer from the fluid sand in the furnace and the furnace wall etc. CONSTITUTION:A waste heat boiler 2 is disposed above a fluidized bed incinerator 1 with their centers being mutually offset, and the waste gas from the incinerator 1 is introduced into the boiler 2. At the time when the incinerator 1 resumes its operation after an interval of suspension, the boiler pressure is maintained at a level closer to that which exists under normal operating conditions while the incinerator 1 is being suspended by making use of a heat transfer from the fluid sand in the incinerator and the incinerator wall etc. In order to maintain the drum pressure of the boiler 2 at a level closer to that which exists under normal operating conditions while the incinerator 1 is being suspended, a pressure control valve 4 is automatically controlled by the deviation between the drum pressure of the boiler 2 and the predetermined set pressure which are compared by a drum pressure adjusting gauge 3.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for semi-continuously operating a fluidized bed incinerator with a boiler, which incinerates municipal waste, etc., and has a boiler installed above the fluidized bed incinerator. It is something.

[Prior art]

Traditionally, municipal waste incineration facilities with boilers have been developed as stoker-type incineration facilities. In the case of a mechanical incinerator, when the furnace is shut down, it takes time for the garbage on the stoker to be completely burnt out, so the garbage is left on the stoker and is burned by natural ventilation while the furnace is out of service. For this reason, since the amount of exhaust gas is small during the furnace shutdown, heat is radiated in the equipment and ducts, resulting in low temperatures that reach the dew point and corrode the equipment and ducts. In many cases, mechanical municipal waste incineration facilities that operate intermittently have a bypass duct installed in the electrostatic precipitator as a countermeasure against corrosion, to prevent exhaust gas from flowing into the electrostatic precipitator while the furnace is out of operation. Therefore, when a boiler is attached after the furnace, corrosion of the boiler tube is taken into consideration, and when the furnace is out of operation, the garbage on the stoker is almost completely incinerated to prevent the generation of corrosive gas.

[Problem that the invention seeks to solve]

However, in the above-mentioned conventional stoker-type municipal waste incineration facility with a boiler, the garbage on the stoker is almost completely incinerated when the furnace is shut down, and there is no heat source inside the furnace, so the boiler can water temperature decreases due to heat radiation from the boiler side. do. Therefore, when starting combustion in a stoker furnace, there is a problem that it takes time to ignite the garbage because the garbage is ignited from a state where there is no garbage in the furnace, and it also takes time to obtain stable steam as the boiler can water temperature rises. . For this reason, in a stoker type municipal waste incineration facility with a boiler, it is common practice to operate continuously day and night, since it takes time to restart once the change is stopped. However, it is necessary to secure nighttime operators,
There were difficult issues such as working conditions.

In recent years, boiler-equipped municipal waste incinerators using fluidized bed furnaces have been developed, but since the conventional boiler-equipped stoker-type municipal waste incinerators operate continuously, the boiler-equipped fluidized bed incinerators with the above structure However, intermittent operation was unthinkable. Therefore, when a fluidized bed incinerator equipped with a boiler is operated continuously, there are problems such as securing nighttime operators as described above. In addition, when the furnace is stopped, the pressure valve of the boiler is manually opened to bring the boiler pressure to zero, so when the boiler is restarted, the water temperature in the boiler can rises and stable steam is obtained. The problem was that it took a long time.

The present invention has been made in view of the above points, and is a semi-continuous operation method for a fluidized bed incinerator with a boiler, which makes intermittent operation of the fluidized bed incinerator with a boiler possible by utilizing the features of the fluidized bed incinerator. Our goal is to provide the following.

[Means to solve the problem]

In order to solve the above-mentioned problems, the present invention provides a fluidized bed incinerator with a boiler having a structure in which a boiler is disposed in the upper part of a fluidized bed incinerator so that the center of the furnace and the center of the boiler are aligned or the center of the furnace and the center of the boiler are shifted. When the fluidized bed incinerator is allowed to stop for a predetermined period of time and then restarted, during the suspension period of the fluidized bed incinerator, the pressure control valve of the boiler and the pressure regulator that controls the pressure control valve are set to the normal operating state. Semi-continuous operation of the fluidized bed incinerator with a boiler is achieved by keeping the boiler pressure close to that of normal operation by using heat input to the boiler from the fluidized sand in the furnace and the furnace walls, etc. made possible.

[Effect]

In the fluidized bed incinerator with a boiler of the above structure, the heat input to the boiler due to waste incineration becomes zero when the furnace is stopped, but as will be explained in detail later, the heat held by the fluidized sand in the furnace and the furnace wall is Since heat is input to the boiler for a long time, the boiler can water temperature and boiler pressure do not drop, and when restarting, the boiler can water temperature and boiler pressure rise and the time required to obtain stable steam is extremely short. Become.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is a diagram showing an outline of the system configuration of a municipal waste incineration facility using a fluidized bed incinerator with a boiler that employs the semi-continuous operation method of the present invention. In the figure, 1 is a fluidized bed incinerator, 2 is a waste heat boiler, 3 is a drum pressure regulator, 4 is a pressure control valve, 5 is a steam flow rate regulator, 6 is a steam flow rate control valve, 7
is residual heat utilization equipment, 8 is a high pressure condenser, 9 is a low pressure condenser, 1
0 is a condensate tank, and 11 is a turbine generator.

The waste heat boiler 2 is disposed above the fluidized bed incinerator 1, with the center of the fluidized bed incinerator 1 and the center of the waste heat boiler 2 being shifted from each other, as will be described in detail later. is led to the waste heat boiler 2. The drum pressure of the waste heat boiler 2 is guided to a drum pressure regulator 3. The drum pressure regulator 3 compares the drum pressure value with a preset pressure value, controls the pressure control valve 4 according to the deviation from the set pressure value, and adjusts the drum pressure of the waste heat boiler 2. Control to achieve the set pressure value. Further, the steam flow rate flowing into the turbine generator 11 is controlled to a predetermined value by controlling the steam flow rate control valve 6 via the steam flow rate controller 5, and the steam discharged from the turbine generator 11 is It is condensed by a low pressure condenser 9 and sent to a condensate tank 10.

In addition, steam that is not supplied to the turbine generator 11 is sent to the residual heat utilization equipment 7 and the high pressure condenser 8 and is condensed in the condensate tank 1.
Sent to 0.

FIG. 2 is a diagram showing the structure of an embodiment of a fluidized bed incinerator with a boiler, in which a waste heat boiler 2 is disposed on the fluidized bed incinerator 1. As shown in the figure, a waste heat boiler 2 is a fluidized bed incinerator 1.
The center of the fluidized bed incinerator 1 and the center of the waste heat boiler 2 are offset by P in the upper part of the incinerator. Inside the fluidized bed incinerator 1, a blower 22 sends air from an air chamber 21 to form a fluidized bed 23 in which hot sand is floating. When you put it in,
The waste is burned at a high combustion rate by the hot sand, and the exhaust gas passes through the freeboard 26 and reaches the water-cooled wall 27 of the waste heat boiler 2.
The gas is discharged from the flue through the gas cooling chamber 28 and the water tube group 29 surrounded by the gas.

Conventionally, in a municipal waste incineration facility having the system configuration shown in FIG. It is opened manually and the boiler pressure of the waste heat boiler 2 is brought to zero as quickly as possible. The next morning, the fluidized bed incinerator 1 is started, and after waiting for the water temperature in the waste heat boiler 2 to rise and stable steam is obtained, the steam is sent to the turbine generator 11 and the like. Therefore, there is a problem in that it takes a long time to start up the equipment, and such municipal waste incineration facilities usually operate continuously day and night.

By the way, since the fluidized bed incinerator 1 with the structure shown in Fig. 2 burns garbage using hot sand, the combustion speed is fast, and when the fluidized bed incinerator 1 is stopped, it takes only 2 to 3 minutes after the garbage input is stopped. When the dust is burned out and the blower 22 is stopped, the hot sand stops flowing and becomes stationary. When the furnace is stopped, heat is radiated from the furnace wall and the sand surface, but since the heat transfer of the sand is poor, there is little heat released during crushing, and when the furnace is stopped at -8, the temperature of the hot sand is small and the temperature drop is small, and fluidized air is sent to remove the garbage. It has been confirmed that combustion can be achieved without using auxiliary fuel by adding . In addition, the waste heat boiler 2 following the fluidized bed incinerator 1 stores heat on the furnace wall of the fluidized bed incinerator 1.
If the pressure of the drum 30 is automatically controlled to the normal operating pressure in response to the heat radiated from the sand surface, the amount of heat received from the furnace that exceeds the amount of heat radiated from the main body of the waste heat boiler 2 will be released as steam. When the amount of heat received decreases, the pressure control valve 4 (see FIG. 1), which is completely connected to the drum 30, closes. Moreover, the water temperature of the waste heat boiler 2 decreases by the amount that the amount of heat released from the body of the waste heat boiler 2 exceeds the amount of heat received from the furnace.

The present invention takes advantage of the characteristics of the fluidized bed incinerator with a boiler,
During the suspension period of the fluidized bed incinerator 1, the fluidized bed incinerator 1 uses heat input to the waste heat boiler 2 from the fluidized sand in the furnace, the furnace wall, etc. to maintain the boiler pressure as close to normal operation as possible. 1
This shortens the so-called device start-up time from the start of combustion to the start of startup of the turbine generator 11, etc., and enables semi-continuous operation of the fluidized bed incinerator with boiler. That is, at the same time as the fluidized bed incinerator 1 is stopped, the conventional operation of reducing the boiler pressure of the waste heat boiler 2 to zero as quickly as possible is stopped, the pressure control valve 4 is controlled by the drum pressure regulator 3, and the drum pressure of the waste heat boiler 2 is This is an operating method that significantly shortens the start-up time of a fluidized bed incinerator with a boiler by maintaining the pressure as close to normal operation as possible.

Figure 3 shows a fluidized bed incinerator with a boiler having the structure shown in Figure 2. After the fluidized bed incinerator is stopped for a predetermined time (12°5 hours in the figure), combustion in the fluidized bed incinerator is started, and the waste heat boiler is turned on. Boiler steam generation amount A, boiler drum pressure B1 boiler inlet gas temperature C, and hearth sand with respect to the time elapsed until the pressure of the drum 30 in No. 2 rises to the pressure during normal operation and the device starts up until stable steam is generated. It is a figure which shows the example of a measurement of the change state of temperature. The fluidized bed incinerator with boiler used for the measurements in the same figure has a drum pressure of waste heat boiler 2 of 1 during normal operation.
9 kg/cm"G. As shown in the figure, the boiler steam generation amount A becomes zero in more than ten minutes when the combustion in the fluidized bed incinerator 1 stops, but the boiler drum pressure B is 12 kg/cm"G.
It can be confirmed that the temperature of the hearth sand of fluidized bed incinerator 1 can be maintained at 19 kg/am''G for 12.5 hours. Moreover, it can be confirmed that the boiler inlet gas temperature of the waste heat boiler 2 is also 300°C or higher.

It can be confirmed that the time from the start of combustion in the fluidized bed incinerator 1 until the boiler steam generation amount A rises to around 9 T/H of normal operation, that is, the device start-up time, is significantly shortened to about 30 minutes.

In the above embodiment, as a fluidized bed incinerator with a boiler, as shown in FIG. An example using a structure with staggered arrangement was shown. As the center of the fluidized bed incinerator 1 and the center of the waste heat boiler 2 are shifted by a predetermined amount in this way, heat is gradually absorbed from the hot sand and the furnace wall while the furnace is stopped, so the boiler pressure is maintained for a longer time. , the time for restarting is shortened.

In addition, as a fluidized bed incinerator with a boiler having a structure in which a waste heat boiler is disposed above a fluidized bed incinerator, there is also one in which the center of the fluidized bed incinerator and the center of the waste heat boiler are substantially aligned. Compared to the fluidized bed incinerator with this structure, which has the center of the fluidized bed incinerator and the center of the waste heat boiler shifted by a predetermined amount as described above, the waste heat boiler absorbs the heat of the hot sand in the fluidized bed. easy.

Therefore, in a fluidized bed incinerator with a boiler of this structure, a considerable amount of heat is absorbed immediately after the furnace shuts down, and a large amount of steam is generated in the waste heat boiler, so the time to maintain boiler pressure in the waste heat boiler is shortened. It is possible to use a suitable driving method.

In the above embodiment, the drum pressure of the waste heat boiler 2 is adjusted by the drum pressure regulator 3 in order to maintain the drum pressure of the waste heat boiler 2 at a value close to the pressure during normal operation during the period when the fluidized bed incinerator 1 is stopped. Compare the value with a predetermined set pressure value,
This is done by automatically controlling the pressure control valve 4 based on the deviation, but this is the only method for maintaining the drum pressure of the waste heat boiler 2 during the shutdown period at a value close to the pressure during normal operation. The point is that during the period when the fluidized bed incinerator 1 is stopped, the heat input to the waste heat boiler 2 from the fluidized sand in the furnace and the furnace wall is used to maintain the drum pressure of the waste heat boiler 2 to a pressure close to that during normal operation. Any method may be used as long as it maintains the same.

In addition, in the fluidized bed incinerator with a boiler having the structure shown in Fig. 2, the fluidized bed incinerator 1 is stopped for a predetermined period, combustion is restarted, and the drum pressure of the waste heat boiler 2 reaches the normal operating pressure state. An example of the measurement results is shown below.

Fluidized bed incinerator shutdown time 14 hours 25 hours
Minutes Approximately 10 minutes 30 hours 00 minutes Approximately 20 minutes 53 hours 20 minutes Approximately 45 minutes According to the above measurement results, for example, fluidized bed incinerator 1 is stopped on Friday evening, continuously stopped on Saturday and Sunday, and combustion is started on Monday morning. Semi-continuous operation is also possible.

Currently, there are many incinerators that can incinerate 100 tons of garbage per day, but only one garbage incinerator that is equipped with a boiler turbine generator and provides electricity for the garbage incineration plant can incinerate more than 300 tons of garbage per day. The amount of incineration per furnace was 150 tons, and it was also subject to continuous operation, but if the semi-continuous operation method of the fluidized bed incinerator with boiler according to the present invention is adopted, the amount of incineration per furnace will be 8 tons.
Even small-scale fluidized bed incinerators such as 0 tons/16 hours or 50 tons/8 hours can be operated with a waste heat boiler and turbine generator attached, which can greatly contribute to energy conservation.

〔Effect of the invention〕

As explained above, according to the present invention, during the suspension period of the fluidized bed incinerator, heat input to the boiler from the fluidized sand in the furnace, the furnace wall, etc. is used to maintain the boiler pressure at a pressure close to that during normal operation. , the restart time of a fluidized bed incinerator equipped with a boiler can be significantly shortened, and semi-continuous operation, for example, where operation can be stopped every night and restarted in a short time the next morning, is possible, making it possible to reduce harsh conditions for the operator. Excellent effects such as not requiring employees to work at night can be obtained.

[Brief explanation of drawings]

Figure 1 is a diagram showing an overview of the system configuration of a municipal waste incineration facility using a fluidized bed incinerator with a boiler that adopts the semi-continuous operation method of the present invention, and Figure 2 shows waste heat generated on top of the fluidized bed incinerator 1. Boiler steam generation amount A, boiler drum pressure B, boiler inlet log gas temperature C, and hearth sand over time from when the fluidized bed incinerator equipped with the boiler is stopped until the start of combustion in the fluidized bed incinerator It is a figure which shows the example of a measurement of the change state of temperature. In the figure, 1... Fluidized bed incinerator, 2... Waste heat boiler, 3... Drum pressure regulator, 4... Pressure control valve, 5... Steam flow rate regulator. , 6... Steam flow rate control valve, 7... Residual heat utilization equipment, 8... High pressure condenser,
9...Low pressure condenser, 10...Condensate tank.

Claims (2)

[Claims] (1) In a fluidized bed incinerator with a boiler having a structure in which a boiler is disposed above the fluidized bed incinerator so that the center of the furnace and the center of the boiler are aligned or the center of the boiler is shifted from the center of the boiler, the fluidized bed incinerator is When the fluidized bed incinerator is stopped for a predetermined period of time and restarted, the boiler pressure is kept close to that of normal operation by utilizing the heat input to the boiler from the fluidized sand in the furnace and the furnace wall, etc. A method for semi-continuous operation of a fluidized bed incinerator with a boiler, characterized by maintaining pressure. (2) To maintain the boiler pressure during the suspension period of the fluidized bed incinerator, the current drum pressure is compared with a predetermined set pressure using a drum pressure regulator, and the pressure control valve is controlled based on the deviation to maintain the boiler pressure. Claim 1 (1) is characterized in that the control method maintains the pressure in a state close to that during normal operation.
) A method for semi-continuous operation of a fluidized bed incinerator with a boiler as described in paragraph 2.