JPH0154604B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a waste incinerator for incinerating waste such as sewage sludge.

(Prior art) Multi-stage incinerators have been widely used to incinerate high-calorie self-combustible wastes such as sewage sludge (for example, Japanese Patent Publication No. 1983-36269), and the incinerators are discharged from the dry zone. Waste incinerators are also widely known in which waste gas is treated by an exhaust gas treatment device including a desulfurization tower and a deodorizing device such as a catalytic reaction tower, and then released into the atmosphere.

(Problem to be solved by the invention) However, in order to perform dehumidification and desulfurization, it is necessary to cool the exhaust gas to around room temperature, and then in order to deodorize it, the exhaust gas must be
℃, and in the case of direct combustion deodorization, it is necessary to heat up to about 800℃, so conventional waste incinerators cool the high-temperature exhaust gas before the desulfurization tower, and then heat the low-temperature exhaust gas that exits the desulfurization tower into the heating furnace. This required a large amount of energy. Attempts have also been made to heat the exhaust gas after desulfurization by recovering heat from the exhaust gas using a heat exchanger, but this has had the problem of adversely affecting the exhaust gas treatment process because the temperature of the exhaust gas constantly fluctuates. Therefore, there has been a need for a waste incinerator that can perform stable exhaust gas treatment using the combustion heat of waste in a multistage incinerator.

(Means for Solving the Problems) The present invention has been completed to solve these conventional problems, and provides an exhaust gas treatment system in which a multistage incinerator includes at least a desulfurization dust collector and a deodorization device. In the waste incinerator to which the device is connected, a heat exchanger for heating the cooled exhaust gas after deflow is installed behind the desulfurization dust collector, and the heating fluid supply port of the heat exchanger is connected to the multistage incinerator. An exhaust duct for discharging combustion gas from the drying zone or combustion zone in the middle stage is connected, and the exhaust duct is equipped with an exhaust volume control valve that detects the temperature of the exhaust gas after being heated by the heat exchanger and adjusts the exhaust volume. It is characterized by this.

(Embodiments) Next, the present invention will be described in detail with reference to illustrated embodiments. In Fig. 1, 1 is a multistage incinerator consisting of a drying zone 2, a combustion zone 3, and a cooling zone 4, 5 is a hearth formed in multiple stages inside the incinerator, and 6 is a stirring arm, which is located above the drying zone 2. Waste such as sewage sludge cake is inputted from the waste input port 7 of the furnace, passes through the steps of drying, combustion, and cooling while sequentially moving downward between the hearths 5, and then exits from the discharge port 8 at the bottom of the cooling zone 4. configured to be ejected. Combustion gas from the multistage incinerator 1 is guided to an exhaust gas treatment device 10 through an exhaust gas duct 9 opened at the top of the drying zone 2, and the exhaust gas treatment device includes a cooling tower 11, a desulfurization tower 12, an electrostatic precipitator 13, and an exhaust gas fan. 14, etc., and a reheating furnace 15 for heating the low-temperature desulfurized exhaust gas to a temperature suitable for deodorization.
and a deodorizing device 33 such as a catalytic reaction tower 16, and discharges the cooled, dehumidified, desulfurized, dust collected, deodorized, and denitrated exhaust gas into the atmosphere from the chimney 17. Desulfurization dust collector 30 and deodorizing device 33
A heat exchanger 18 that heats the cooled exhaust gas after desulfurization is provided between the incinerator 1 and the exhaust duct 19 that constantly exhausts high-temperature combustion gas from the drying zone 2 or the combustion zone 3 of the multistage incinerator 1. It is connected to the heating fluid supply port 20 of the heat exchanger 18 . Exhaust duct 1
9 is provided with an exhaust amount control valve 21, which is controlled by a temperature controller 22 and detects the temperature of the exhaust gas after being heated by the heat exchanger 18 with a thermometer 23; The amount of exhaust gas is adjusted so that the exhaust gas temperature remains constant. The combustion gas that is constantly exhausted in the middle stage through the exhaust duct 19 is given heat by the heat exchanger 18, and then sent to the exhaust gas treatment device 10 together with the exhaust gas led from the drying zone 2 through the exhaust gas duct 9. Note that 24 is an auxiliary heat exchanger provided before the heat exchanger 18, and is for preheating the exhaust gas after desulfurization using the high temperature exhaust gas exiting the deodorizing device 33 as a heat source. Reference numeral 25 is a circulation duct connected to the exhaust gas duct 9, and the circulation fan 26 circulates a part of the exhaust gas from the drying zone 2 to the combustion zone 3 or the cooling zone 4, thereby increasing the temperature of the combustion zone 3. is kept constant. This temperature control is performed by opening and closing the circulation amount control valve 27 of the circulation duct 25 using the combustion temperature regulator 29 so that the temperature of the combustion zone 3 detected by the thermometer 28 is constant. When the temperature of zone 3 shows an increasing tendency, the temperature of combustion zone 3 can be immediately lowered by opening the circulation amount control valve 27 and circulating a large amount of relatively low-temperature exhaust gas to combustion zone 3 or cooling zone 4. becomes.

In a second embodiment of the invention shown in FIG.
The reheating furnace 15 is placed in front of the heat exchanger 18, and the temperature controller 22 is connected to the exhaust volume control valve 2 so that the exhaust gas temperature after being heated by the heat exchanger 18 is constant.
1 and also controls the reheating furnace 15. The rest of the configuration is the same as that of the embodiment shown in FIG. 1, so the same reference numerals will be given and the explanation will be omitted. Furthermore, the third embodiment shown in FIG. 3 uses a deodorizing furnace 3 as a deodorizing device 33.
4, and in this case, the reheating furnace 1
5 and the catalytic reaction column 16 can be omitted.

(Function) In this structure, the burner 31 sets the temperature of the combustion zone 3 of the multistage incinerator 1 to a temperature higher than that required for burning the waste, and then the pipe 32
If waste such as sewage sludge cake is inputted from the waste inlet 7 while supplying air for waste combustion from the drying zone 2, the waste will come into contact with the upward gas flow in the drying zone 2, be dried and then combusted. It is burned in the zone 3 and discharged as incinerated ash from the discharge port 8 below the cooling zone 4, while the exhaust gas discharged from the drying zone 2 is passed through the exhaust gas duct 9 to the exhaust gas containing the desulfurization dust collector 30 and the deodorizing device 33. The waste is desulfurized and deodorized by the treatment device 10 and discharged from the chimney 17, which is the same as in the conventional waste incinerator. However, in the present invention, a heat exchanger 18 is provided between the desulfurization dust collector 30 and the deodorizing device 33, and an exhaust duct 19 for discharging combustion gas from the drying zone 2 or the combustion zone 3 of the multistage incinerator 1 is also provided. Since it was connected to the heating fluid supply port 20 of the heat exchanger 18, the fluid that exited the desulfurization tower 12
The exhaust gas at about 40℃ is heated to about 250℃ by the secondary heat exchanger 24.
After being heated to approximately 100°C, the heat exchanger 18 receives heat from the high temperature combustion gas of approximately 800°C exhausted in the middle stage, and is heated to approximately 400°C and sent to the deodorizing device 33, where it is sent to the reheating furnace. The catalytic reaction column 1 requires almost no external heating by 15.
It is deodorized and denitrated in a deodorizing device 33 such as 6. Further, the exhaust gas temperature after being heated by the heat exchanger 18 is constantly detected by a thermometer 23, and the exhaust gas temperature is constantly detected by the exhaust duct 1 so that the temperature is constant.
Since the exhaust volume control valve 21 provided at the incinerator 9 is opened and closed, the temperature of the exhaust gas sent to the deodorizing device 33 is constant regardless of fluctuations in the temperature inside the multistage incinerator 1, and almost no external energy is used. Therefore, stable exhaust gas treatment will be performed. A part of the exhaust gas discharged from the drying zone 2 is circulated to the combustion zone 3 or the cooling zone 4 by the circulation duct 25, and high-temperature combustion gas is constantly exhausted from the drying zone 2 or the combustion zone 3 in the middle stage. Therefore, there is no risk that the temperature of the combustion zone 3 will rise abnormally, and there is also the advantage that damage to the furnace wall and clinker formation can be prevented.

(Effects of the Invention) As is clear from the above description, the present invention provides a heat exchanger at the rear of the desulfurization tower, and connects an exhaust duct for discharging combustion gas to the heating fluid supply port of the heat exchanger. At the same time, the exhaust duct is equipped with an exhaust volume control valve that detects the temperature of the exhaust gas after heat exchange and adjusts the exhaust volume, so that the low-temperature combustion gas after desulfurization can be used for combustion of the waste exhausted in the middle stage. Using heat, it can be heated to the temperature required to send it to the deodorizing device, and for this reason almost no external energy supply is required. In addition, since the temperature of the exhaust gas sent to the deodorization device is constant, stable exhaust gas treatment can be performed, and by exhausting high-temperature combustion gas in the middle stage, damage to the furnace wall and clinker formation can be effectively prevented. It can also be prevented. Therefore, the present invention solves the problems of conventional waste incinerators of this type and contributes greatly to the development of industry.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a first embodiment of the present invention;
FIG. 2 is a schematic diagram showing a second embodiment of the invention, and FIG. 3 is a schematic diagram showing a third embodiment of the invention. 1: Multistage incinerator, 2: Drying zone, 3: Combustion zone, 1
0: Exhaust gas treatment device, 18: Heat exchanger, 19: Exhaust duct, 20: Heated fluid supply port, 21: Exhaust volume control valve, 30: Desulfurization dust collector, 33: Deodorizing device.

Claims (1)

[Claims] 1 At least a desulfurization dust collector 30 is provided in the multistage incinerator 1
In a waste incineration device to which an exhaust gas treatment device 10 including a deodorizing device 33 and a deodorizing device 33 are connected, a heat exchanger 18 for heating the cooled exhaust gas after desulfurization is provided behind the desulfurization dust collector 30, and the heat exchanger 18 The heating fluid supply port 20 of 18 is provided with an exhaust duct 1 for exhausting combustion gas from the drying zone 2 or combustion zone 3 of the multistage incinerator 1 in the middle stage.
9 is connected to the exhaust duct 19, and the exhaust duct 19 is provided with an exhaust amount control valve 21 that detects the temperature of the exhaust gas heated by the heat exchanger 18 and adjusts the exhaust amount.