JPS6149921A - Waste incinerating device - Google Patents

Abstract

PURPOSE:To decrease useless consumption of energy to a minimum and to perform stable disposal of exhaust gas, by a method wherein a desulfurizing tower, a heat exchanger which heats exhaust gas after desulfurization, and a deodorizing device are connected to a multistage incinerator, a bleed duct, bleeding combustion gas from the multistage incinerator, is connected to the heat exhanger, and a bleed amount control valve, controlling a bleed air amount, is provided. CONSTITUTION:A heat exhanger 15 is adapted to heat exhaust gas, flowing out from a desulfurizing tower 11, by means of high temperature exhaust gas which flows out from a deodorizing device 12 and serves as a heat source A bleed duct 17, bleeding high temperature exhaust gas from the combustion stage of a multistage incinerator 1, is connected to the heating fluid feed port of the heat exchanger 16 which heats exhaust gas flowing out from the heat exchanger 15. Through detection of temperature in an incinerator at the drying stage or the combustion stage of the multistage incinerator 1, a difference signal between the detecting temperature and a reference temperature in the incinerator is provided, and through detection of the temperature of exhaust gas on the outlet side of the heat exchanger 16, a difference signal between the detecting temperature and an exhaust gas reference temperature is provided. The difference signal, which is smaller, of the above difference signals is selected, and a bleed amount control valve 18 is operated so that the difference signal is controlled into about zero.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a waste incinerator comprising a multistage incinerator and an exhaust gas treatment device used to incinerate waste such as sewage sludge.

(Prior technology) Multi-stage incinerators have been widely used to incinerate high-calorie combustible wastes such as dehydrated cakes of sewage sludge. In order to prevent the temperature inside the furnace from fluctuating beyond the permissible range due to fluctuations in the amount, high-temperature combustion gas is extracted from the combustion stage when the temperature of the combustion stage in the furnace rises above the permissible value. There are also known devices that control the temperature of the combustion stage by adjusting the exhaust gas circulation flow. (For example, Japanese Patent Publication No. 48-36269, Japanese Patent Application Laid-Open No. 58-55608) (Problems to be Solved by the Invention) However, in the conventional waste incinerator as described above, only the temperature control inside the furnace is possible. Targeted control is in place,
There was insufficient consideration given to the optimal temperature control of the entire waste incinerator, including the exhaust gas treatment equipment of the multistage incinerator. In other words, in this type of waste incinerator installed in the suburbs of cities, it is essential to desulfurize the exhaust gas containing extracted gas in a desulfurization tower and then deodorize it in a deodorization device such as a deodorization furnace or catalytic reaction tower. Complex temperature control is also required for the exhaust gas that passes through these exhaust gas treatment devices, but in the past, these exhaust gas treatment processes were ignored and extraction etc. were performed, resulting in high temperature combustion gas. If a large amount of air is extracted, the temperature of the exhaust gas sent to the exhaust gas treatment equipment becomes unstable, and when looking at the system as a whole, it is easy to prevent wasted energy, and the disadvantage is that it is difficult to perform stable exhaust gas treatment. there were.

(Means for Solving the Problems) The present invention was completed in order to solve these conventional problems, and includes a multistage incinerator, a desulfurization tower, and a heat exchanger for heating the exhaust gas after desulfurization. A deodorizing device is connected to the heat exchanger, and a bleed duct for extracting combustion gas from the multi-stage incinerator is connected to the heated fluid supply port of the heat exchanger. A difference signal (T-Ts) between the furnace reference temperature (Ts) and a difference signal (t-Ts) between the exhaust gas temperature (1) on the outlet side of the heat exchanger and the exhaust gas reference temperature (ts).
The present invention is characterized in that a bleed air amount control valve is provided, which includes a controller that selects the smaller difference signal among ts) and controls the bleed air amount so that the difference signal approaches zero.

(Example) Next, the present invention will be explained in detail with reference to the illustrated example.
(1) is a 10-stage type multi-stage incinerator, with the upper (T
1) to (T4) are drying stages, and the center (T5) to (T
9) is the combustion stage, and the bottom (TlO) is the cooling stage. A waste inlet (2) and an exhaust gas outlet (3) are provided at the top of the multistage incinerator (1), while an incinerated ash outlet (4) is provided at the bottom, ie, the lower part of the cooling stage. The combustion stage has a hot air duct (6) that blows hot air from the hot air furnace (5).
) is connected to an exhaust gas duct (7) for circulating a part of the relatively low temperature exhaust gas flowing out from the exhaust gas outlet (3), and a valve (8
), (9) are controlled by the controller α0) to maintain the furnace internal temperature constant, as in the conventional multistage incinerator. (
11) is a desulfurization tower that constitutes a part of the exhaust gas treatment equipment, and the high-temperature exhaust gas is cooled to a temperature suitable for desulfurization inside the tower, and then desulfurized and dust is removed. Further, (12) is a deodorizing device composed of a heating furnace (13) and a deodorizing furnace (14) that heat the low-temperature exhaust gas exiting the desulfurization tower (11) to a high temperature suitable for deodorizing. In this way, the exhaust gas needs to be heated to a high temperature for deodorization after being cooled by the desulfurization tower (11), so in order to effectively use thermal energy, a desulfurization tower (11) and a deodorization device (12) are installed. Two heat exchangers (15) and (16) are provided between the two. The heat exchanger (15) uses the high temperature exhaust gas exiting the deodorizing device (12) as a heat source to heat the exhaust gas exiting the desulfurization tower (11) at around 40°C to around 250°C. The heat exchanger (16) also has a multistage incinerator (1) at its heating fluid supply port.
) is connected to the bleed duct) (17) which bleeds high temperature combustion gas of about 800'C from the combustion stage of the heat exchanger (15
) is heated to around 400°C. (18) is the bleed air amount control valve installed in the bleed air duct (17), (19) is the controller, and (20) is the multistage incinerator (1).
The thermometer (21) is installed in the drying stage of the heat exchanger (1
6) is a thermometer installed near the outlet of the controller (
19) controls the bleed air amount control valve (18) as follows.

That is, the temperature inside the furnace (T) of the drying stage or the combustion stage of the multistage incinerator (1) is detected by the thermometer (20), and a difference signal (T-Ts) between the inside temperature (T) and the preset inside temperature (Ts) is detected. ), while the heat exchanger (16) by the thermometer (21)
Detects the exhaust gas temperature (1) on the outlet side of the exhaust gas, creates a difference signal (t-ts) from the preset exhaust gas reference temperature (ts), and then selects the smaller of these difference signals. Based on the selected difference signal, the bleed air amount control valve (18) is opened and closed so as to bring it closer to zero.

As shown in the figure, the extracted exhaust gas is sent to the desulfurization tower (11) after passing through the heat exchanger (16).

(Function) In this type of incinerator, the temperature of the combustion stage of the multi-stage incinerator (1) is made higher than the temperature necessary for burning the waste using hot air from the hot blast furnace (5), and then the waste is supplied. Mouth (2)
When a waste material such as a dehydrated cake of sewage sludge is inputted from the drying stage, the waste material is dried by contact with the upward gas flow in the drying stage, and then ignited and burned in the combustion stage, and the incinerated ash is discharged in the lower part of the cooling stage. While it is discharged as incineration ash from the outlet (4), part of the flue gas discharged from the flue gas outlet (3) is circulated to the combustion stage via the flue gas duct (7), and the remainder is sent to the desulfurization tower (11). After desulfurization and dust removal are carried out, a deodorizing device (
12) and is discharged from the chimney (22) in the same manner as in conventional waste incinerators. However, in the present invention, a heat exchanger (16) is provided which heats the exhaust gas after desulfurization using the high temperature extracted gas extracted from the multistage incinerator (1) as a heat source, and the heat exchanger (16) The bleed air duct (17) that supplies the bled combustion gas to the bleed air amount control valve (17) is equipped with the controller (19) as described above.
18), the amount of extracted air is controlled as shown in the following table in response to changes in the temperature distribution inside the furnace due to changes in the calorific value and moisture content of waste.

As is clear from the table above, even when the temperature inside the furnace (T) is higher than the standard temperature inside the furnace (Ts), air extraction is not performed for the sole purpose of lowering the furnace temperature as in the past, but basically The bleed air amount control valve (18) is controlled so that (t-ts) approaches zero with the difference signal (t-ts> as a reference, and conversely, the furnace temperature (T) becomes the furnace standard temperature (Ts). ), the bleed air amount control valve (18) is basically controlled to improve the furnace temperature (T) based on the difference signal (T-Ts). Also (T-Ts) and (
When t-ts) have the same sign, the amount of bleed air is increased or decreased depending on the magnitude, which is an unprecedented fine-grained control of the amount of bleed air. I11 will be performed. Therefore, when viewed as a whole system consisting of the multistage incinerator (1) and the exhaust gas treatment device, stable exhaust gas treatment can be performed while minimizing energy waste.

In the above explanation, the bleed air amount control valve (18) is a single one, but as shown in the figure, the bleed air amount control valve (18a) may be provided individually in each stage of the bleed duct. may be performed starting from the combustion stage with the highest temperature. Furthermore,
In the illustrated embodiment, the thermometer (20) is installed in the drying stage, but it goes without saying that it may be installed in the combustion stage.

(Effects of the Invention) As is clear from the above description, the present invention controls the amount of extracted air by taking into account not only the multistage incinerator but also the exhaust gas temperature of the exhaust gas treatment device connected to the multistage incinerator. Therefore, the waste incinerator as a whole can perform stable exhaust gas treatment while minimizing the waste of thermal energy, and solves the problems of conventional waste incinerators of this type. The contribution it makes to the development of industry is extremely large.

[Brief explanation of drawings]

The drawing is an explanatory layout diagram showing an embodiment of the present invention (1):
Multistage incinerator, (11): Desulfurization tower, (12): Deodorizing device, (16): Heat exchanger, (17): Bleeding duct, (18
): Bleed air amount control valve, (19): Controller.

Claims (1)

[Claims] A desulfurization tower (11), a heat exchanger (16) for heating the flue gas after desulfurization, and a deodorizing device (12) are connected to the multistage incinerator (1), and a heated fluid supply port of the heat exchanger (16) is connected to the desulfurization tower (11). is connected to an air extraction duct (17) that extracts combustion gas from the multi-stage incinerator (1), and the air extraction duct (17) is connected to the furnace temperature (T) of the multi-stage incinerator (1) and the furnace reference temperature ( Ts) and the difference signal (T-Ts) and the difference signal (Ts) between the exhaust gas temperature (t) on the outlet side of the heat exchanger (16) and the exhaust gas reference temperature (ts).
A controller (1) selects the smaller difference signal of
9) A waste incinerator characterized in that it is provided with a bleed air amount control valve (18).