JPH0646092B2 - Waste heat recovery type sludge incinerator - Google Patents

Description

TECHNICAL FIELD The present invention relates to a waste heat recovery type sludge incineration facility.

[Prior Art] In recent years, sludge incinerators such as sewage sludge and human waste sludge are often provided with a sludge dryer, a waste heat boiler, etc. for the purpose of energy-saving incineration.

FIG. 2 shows an example thereof. 1 is a sludge fluidized incinerator, 2
Is a fluidized air preheater, 3 is a waste heat boiler, and 4 is a sludge dryer. The exhaust gas from the incinerator 1 first enters the air preheater 2 to preheat the flowing air fed from the blower. Next, the heat of the exhaust gas is recovered by the waste heat boiler 3 to generate steam.
A part of the generated steam is sent to the sludge dryer 4 and used for drying the sludge. The exhaust gas after the heat recovery is subjected to dust collection and cleaning processing in the processing device 5, and is discharged from the chimney 6.

[Problems to be Solved] However, the above conventional equipment has the following problems.

Due to changes in the properties (moisture content, calorific value) of sludge, which is the material to be incinerated, the generated exhaust gas temperature and air volume fluctuate, and these are brought into the waste heat boiler as they are, causing fluctuations in the amount of generated steam.

On the other hand, the amount of steam consumed in the sludge dryer is the water content of sludge,
It can be said that it is uniquely determined by the amount of sludge input,
Therefore, the steam consumption fluctuates due to a factor completely different from the amount of steam generated by the waste heat boiler.

As a result, these fluctuations become apparent as an excess or deficiency of the steam amount. In particular, when the amount of sludge heat exceeds the self-burning point, the amount of combustion exhaust gas also increases, and as a result, the amount of steam generated in the waste heat boiler also increases, but the amount of steam required by the sludge dryer decreases conversely. (Since the amount of sludge heat is high, the degree of drying must be lowered.) Therefore, the steam balance is disturbed and stable operation of the plant becomes impossible.

Therefore, in such a case, there is no choice but to take a method of reducing the amount of sludge input to the incinerator to reduce the amount of combustion exhaust gas and thus the amount of steam generated in the boiler. However, depending on the frequency and the period, this measure will inevitably affect the overall sludge treatment at the sewage treatment plant, which is a big problem.

Moreover, the waste heat boiler is obliged to carry out a periodic inspection once a year, and the entire incineration plant must be stopped during that period, and the sludge incineration process during that period is also a problem of the system. .

It is an object of the present invention to provide a waste heat recovery type sludge incinerator capable of solving the above problems.

[Means for Solving Problems] The waste heat recovery type sludge incinerator of the present invention comprises a sludge incinerator,
In a waste heat recovery type sludge incinerator equipped with a waste heat boiler that recovers the heat of the exhaust gas of this incinerator, a weight control device provided in a system for drying the treated sludge and sending it to the incinerator, and the treated sludge. Is installed in the system for directly throwing the waste heat into the incinerator, the pressure control device for controlling the generated steam pressure by controlling the amount of exhaust gas passing through the waste heat boiler, and the bypass path of the waste heat boiler. It comprises an exhaust gas cooler and a temperature control device for controlling the outlet gas temperature by controlling the refrigerant amount of the exhaust gas cooler.

[Operation] While keeping the total amount of sludge into the incinerator at the planned value by the weight control devices provided in the dry system and the direct throw system,
The amount of exhaust gas generated will be stabilized by changing the input ratio between the dry system and the direct injection system depending on the sludge properties. Further, the generated steam pressure is maintained constant by controlling the amount of exhaust gas passing through the waste heat boiler by the pressure control device. Then, even if the bypass flow rate changes due to this control, the temperature control device controls the gas cooler outlet temperature so as not to adversely affect the subsequent exhaust gas treatment device.

In addition, during the boiler regular inspection, the exhaust gas is bypassed entirely and is allowed to flow into the gas cooler for periodic inspection of the boiler. It also prevents adverse effects on the device.

[Embodiment] An embodiment of the present invention will be described below with reference to FIG. Here, the same components as those of the conventional one shown in FIG. 1 are denoted by the same reference numerals in the drawings, and detailed description thereof will be omitted.

The sludge cake after dehydration is fed from the hopper 11 to the sludge dryer 4
It is designed to be put into the fluidized incinerator 1 through a drying system 12 and a direct throwing system 13 each equipped with. The drying system 12 and the direct throwing system 13 are respectively provided with weight control devices 14 and 15 for controlling the amount of sludge input. Then, the set values of the weight control devices 14 and 15 are set to the in-furnace temperature control device 1 of the incinerator 1.
6 is set.

The waste heat boiler 3 is provided with a pressure control device 21 that detects the pressure of the drum 3a and keeps the generated steam pressure at a predetermined value.
The amount of exhaust gas passing through the boiler 3 is controlled by the valve 2 provided at the boiler outlet.
It is controlled by 2.

A bypass 30 is provided in the waste heat boiler 3, and an exhaust gas cooler 31 is provided in this bypass. This gas cooler is designed to cool the gas using the air sent from the blower 33 as a refrigerant. A temperature control device 32 is provided to control the amount of air sent from the blower 33 and maintain the outlet gas temperature at a predetermined value. On the other hand, the air that has been heat-exchanged and heated is guided to the chimney 6 through the pipe 35 to prevent white smoke in the exhaust gas from the chimney.

Next, the operation of the above device will be described.

The water content of the sludge cake after dehydration is about 80%, and about 30% of the total amount of the sludge cake is put into the incinerator 1 from the drying system 12 and the remaining 70% from the direct throwing system 15. The temperature and air volume of the exhaust gas generated from the incinerator 1 vary depending on the properties of the sludge (water content, calorific value). Therefore, the fluctuation of the generated exhaust gas due to the fluctuation of the sludge property is captured as the fluctuation of the temperature inside the incinerator 1, and the temperature control device 1
By 6, the distribution ratio of the input sludge to the drying system 12 and the direct throwing system 13 is changed. For example, when the water content of the sludge cake decreases, the furnace temperature rises, so the rate of addition from the drying system is decreased. In this case, since the amount of solid content charged into the incinerator is almost constant, the amount of exhaust gas generated hardly changes. In this way, exhaust gas can be stably generated from the incinerator 1.

Although the generated exhaust gas amount can be stabilized by the above, the drum pressure changes due to the change in the steam consumption amount.
Therefore, the amount of exhaust gas passing through the boiler 3 is controlled by the pressure control device 21 in order to supply constant steam to the consumer. In this way, steam with a constant pressure can be supplied to the destination.

On the other hand, the amount of exhaust gas flowing through the bypass 30 changes with the above operation. For example, when the amount of exhaust gas passing through the boiler 3 is reduced, the amount of exhaust gas flowing through the bypass passage 30 increases. In this case, in order to prevent the exhaust gas cooler 31 outlet temperature from increasing and adversely affecting the gas treatment device 5, the temperature control device 32 increases the amount of refrigerant air to maintain the outlet gas temperature constant.

Further, at the time of periodic inspection of the boiler 3, the valve 22 is fully closed,
In addition, the direct throwing system operation mode in which the drying system 12 and the dryer 14 are stopped is selected and the incineration operation is performed. The total amount of incinerator exhaust gas is introduced into the gas cooler 31 by the bypass passage 30. At this time,
Since the required amount of heat absorption in the gas cooler 31 increases about 5 times that in normal times, the amount of refrigerant air is also increased about 3 times accordingly, so that the gas cooler outlet temperature does not affect the gas processing device 5 in the subsequent stage. Cool down. These are performed by the controller 32. In this case, since the service point of the refrigerant blower 33 is about ⅓ of the maximum value, the blower 33 is subjected to inverter control, vane control, etc. in order to save energy during normal use.

In the above example, the temperature of the exhaust gas cooler outlet is detected and the temperature is controlled, but the same effect can be obtained by detecting the temperature of the cooler outlet of the refrigerant air and controlling the temperature. Further, water may be used as the coolant of the cooler to cool the gas by spraying. Further, although the control valve 22 for the amount of exhaust gas passing through the boiler 3 is provided at the boiler outlet, it goes without saying that it may be provided at the boiler inlet.

Next, the operation results of an actual furnace incorporating the above device will be described. However, in this actual furnace, unlike the above embodiment, the temperature detection device of the temperature control device 32 is at the cooler outlet air temperature.

Nominal incinerator capacity 70t / d Sludge condition Moisture content 71 to 78 (73.2 on average)% Calorific value 730 to 410kcal / Kg Amount of treated sludge Average 2306 (max 2540, min 2070) Kg / h 55.3t / d Dry Average 926 (maximum 1060, minimum 640) Kg / h 22.22 / t / d Waste heat boiler Inlet gas temperature 720-780 ° C Outlet gas temperature 180 ° C Generated steam amount 2000-900Kg / h Generated steam pressure 7.0 ± 0.8atg (Set value 7.0atg) Cooler outlet air temperature 180 ± 10 ℃ (Set value 180 ℃) As mentioned above, treat the sludge with a treatment amount that exceeds the design value, regardless of fluctuations in the water content and calorific value of the sludge. In addition, it was possible to generate steam at a constant pressure and to control the gas cooler outlet temperature to a predetermined value.

[Effects of the Invention] The waste heat recovery type sludge incineration facility of the present invention is as described above, and of course, the target amount can be treated regardless of the change in the property of the treated sludge, and the exhaust gas treating apparatus is of course possible. It is possible to generate steam at a constant pressure without adversely affecting. Further, the sludge incineration operation can be continued even during the periodic inspection of the waste heat boiler.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of the present invention, and FIG. 2 is an explanatory view of a conventional waste heat recovery type sludge incineration facility. 1 ... Sludge incinerator, 3 ... Waste heat boiler, 4 ... Sludge dryer, 12 ... Drying system, 13 ... Direct throwing system, 14, 15 ...
Weight control device, 21 ... Pressure control device, 30 ... Bypass passage, 31 ... Exhaust gas cooler, 32 ... Temperature control device

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Shuro Inokawa 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (56) References JP-A-59-89921 (JP, A) JP-A-SHO 59-229105 (JP, A) Actual opening 58-46902 (JP, U) Actual opening 56-66604 (JP, U) Actual opening 62-62123 (JP, U)

Claims (1)

[Claims] 1. A waste heat recovery type sludge incinerator equipped with a sludge incinerator and a waste heat boiler for recovering heat of exhaust gas from the incinerator, to a system for drying treated sludge and sending it to the incinerator. A weight control device provided, a weight control device provided in the system that directly throws the treated sludge to the incinerator, a pressure control device that controls the generated steam pressure by controlling the amount of exhaust gas passing through the waste heat boiler, A waste heat recovery type sludge incinerator comprising an exhaust gas cooler provided in a bypass path of a waste heat boiler and a temperature control device for controlling an amount of refrigerant in the exhaust gas cooler to control an outlet gas temperature.