JPH0256566B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for pre-drying and incinerating sludge that cannot self-combust due to its high moisture content and low calorific value. The dehydrated sludge is characterized by pre-drying using the exhaust gas from the dehydrated sludge, and by supplementing the insufficient amount of heat for pre-drying by adding granular auxiliary fuel to the dehydrated sludge. It is something to do.

Normally, organic sludge is dehydrated, pre-dried, and then incinerated for disposal. In this case, the amount of heat required to pre-dry the dehydrated sludge uses the heat generated when the pre-dried sludge is incinerated, but since dehydrated sludge contains 70-90% water. Depending on the amount of heat generated from the heatable components in the sludge, it may not be possible to dry the dehydrated sludge to a combustible state. In such a case,
A method is sometimes adopted in which combustible powder such as wood powder or powdered charcoal is added to sludge as an auxiliary fuel.
Conventionally, it was not possible to determine the appropriate amount of auxiliary fuel to be added, that is, the minimum amount sufficient to dry dehydrated sludge, so auxiliary fuel was added in excess.
Measures were taken to cool down excess heat by misting water.

The present invention has been made in view of the above points, and it automatically adds auxiliary fuel to sludge in an appropriate amount, thereby reducing the amount of auxiliary fuel consumed. At the same time, it also suppresses wear and tear on the incinerator and dryer due to excessive addition of auxiliary fuel.

Hereinafter, the present invention will be specifically explained based on illustrated embodiments.

In the figure, numeral 1 is a dryer, and 2 is an incinerator. The dryer 1 pre-dries dehydrated sludge to a combustible state, and the incinerator 2 incinerates the dried sludge and serves as a source of hot air for the dryer 1. The dryer 1 is the same as a normal dryer of this type, and a horizontal rotary drum dryer is used as an example. Reference numeral 3 denotes a sludge supply hopper for supplying dehydrated sludge to the dryer 1.
The supply hopper 3 is formed so as to be able to supply dehydrated sludge to the dryer 1 at an appropriate speed.For example, a screw is attached to the bottom of the supply hopper 3, and the screw is rotated. By this, dewatered sludge is supplied at a speed corresponding to the rotational speed of the screw. The dehydrated sludge is dried in the dryer 1 until it reaches a predetermined moisture content by contacting hot air sent from an incinerator 2, which will be described later, and is discharged outside the machine and placed in a dry sludge tank 4.

On the other hand, the high-humidity exhaust gas discharged outside the machine passes through the exhaust gas treatment device 5 and is discharged into the atmosphere. Reference numeral 6 is an addition hopper for adding auxiliary fuel to sludge;
Although not shown, it is formed so that the amount added can be automatically adjusted. The reason why the addition hopper 6 is configured as shown in the figure is to enhance the sludge drying effect by using the auxiliary fuel as a drying aid for the dehydrated sludge. That is, when the dehydrated sludge has viscosity and tends to form lumps in the dryer 1, it is necessary to loosen the sludge. In such a case, by mixing granular auxiliary fuel with dehydrated sludge, a dispersion effect of the sludge can be obtained in the dryer, which has the advantage of making drying easier. There is also the advantage that combustion in the furnace is uniformly carried out because the fuel is discharged from the dryer in a state in which the fuel is trapped. The dried sludge containing auxiliary fuel put into the dry sludge tank 4 is transferred to the supply hopper 7 and put into the incinerator 2. The incinerator 2 is the same as a normal powder incinerator of this type, and a fluidized bed incinerator is used as an example. From ventilation fan 8 to incinerator 2
The amount of combustion air supplied to the incinerator 2 is adjusted by a flow rate adjustment device 9.
The high-temperature hot air discharged from the dryer 1 is introduced into the dryer 1. Incidentally, the incineration capacity of the incinerator 2 is such that it can generate the amount of heat necessary for drying the dryer 1, and the incinerator 2 is designed so as not to be at least less than that amount. Furthermore, when this device is operating in a steady state, dehydrated sludge is fed into the dryer 1 at a constant rate, and the auxiliary fuel is fed to the sludge at the minimum mixing ratio required. (at a constant rate).

By the way, in this device, the addition rate of the auxiliary fuel, in other words, the mixing amount to the dehydrated sludge is controlled so that the amount is appropriate for the dehydrated sludge.
That is, the dry sludge tank 4 is equipped with a level gauge 10, and when the dry sludge in the tank 4 falls below a predetermined level, the control device 11 increases the rate of addition of auxiliary fuel from the addition hopper 6. As the level increases, the rate of addition is slowed down. Further, a temperature detector 12 is provided in the exhaust path of the exhaust gas discharged from the dryer 1.
When the temperature of the exhaust gas falls below a predetermined temperature, the opening degree of the flow rate adjustment device 9 is increased by the control device 13 to increase the amount of air blown to the incinerator 2, and when the temperature of the exhaust gas rises, the amount of air blown is decreased. . The incinerator 2 is also equipped with a temperature detector 14, and when the temperature inside the furnace falls below a predetermined temperature, the control device 1 is activated.
5 increases the input amount of dried sludge from the supply hopper 7, and when the temperature rises above a predetermined temperature, decreases the input amount to keep the temperature inside the incinerator 2 constant regardless of changes in the amount of air fed into the incinerator 2. The structure is such that hot air at a constant temperature is sent to the dryer.

Further, the supply hopper 7 is also equipped with a level gauge 16, and is configured such that the dried sludge in the dry sludge tank 4 is fed into the supply hopper 7 when the dried sludge in the hopper falls below a certain level.

Next, a control procedure for adjusting the amount of auxiliary fuel added to the dehydrated sludge will be explained.

First, it is assumed that the device is operating in a steady state. In this state, it is assumed that dehydrated sludge with a higher water content than normal is fed into the dryer 1 from the sludge supply hopper 3. Then, the temperature of the exhaust gas decreases by the amount of moisture contained in the sludge, so the temperature detector 12 detects this decrease in temperature, and the control device 13 operates to increase the opening degree of the flow rate adjustment device 9. Increase the amount of air fed into the incinerator 2. Then, the temperature inside the furnace decreases accordingly, and this is detected by the temperature detector 14, and the control device 15 is activated to increase the amount of dried sludge input into the incinerator 2, thereby lowering the temperature inside the furnace. to rise.

As a result, the amount of heat supplied to the dryer 1 increases. On the other hand, when the amount of dried sludge input to the dryer 1 increases, the level of dried sludge in the dried sludge tank 4 decreases by that amount, so the control device 11 operates to increase the amount of auxiliary fuel added. do.

On the other hand, when the moisture content of dehydrated sludge is low, the amount of air fed into the incinerator 2 is reduced and the input speed of dried sludge is slowed down, so the level of dried sludge in the dried sludge tank 4 increases, but Therefore, the amount of auxiliary fuel added decreases.

In this way, the amount of auxiliary fuel added is increased or decreased as the moisture content of the dehydrated sludge changes, and auxiliary fuel suitable for incineration is mixed with the sludge, eliminating wasteful incineration of auxiliary fuel.

[Brief explanation of drawings]

The figure is a system diagram showing one embodiment of the present invention. 1; Dryer, 2; Incinerator, 3; Sludge supply hopper, 4; Dry sludge tank, 5; Exhaust gas treatment machine,
6; Addition hopper, 7; Supply hopper, 8; Blow fan, 9; Flow control device, 10, 16; Level gauge, 12, 14; Temperature detector, 11, 13, 1
5; Control device.

Claims (1)

[Claims] 1. An incinerator, a dryer, and a sludge tank are provided, the dryer is charged with dehydrated sludge and pre-dried, the dried sludge tank stores the pre-dried sludge, and the incinerator is supplied with dehydrated sludge and pre-dried. In a sludge incinerator, dry sludge is fed from a dry sludge tank and incinerated, and the resulting combustion gas is used as a heat source for drying the dryer. A control device that increases or decreases the amount of air supplied to the incinerator according to the temperature, and maintains the temperature of exhaust gas from the dryer at a predetermined temperature; detects the internal temperature of the incinerator and releases air from the dry sludge tank depending on the temperature. A control device that increases or decreases the amount of dried sludge supplied to the incinerator and maintains the temperature inside the incinerator at a predetermined temperature, a supply device that supplies solid auxiliary fuel in the form of powder into the sludge before or after pre-drying. , a control device that detects the level of dried sludge in the dried sludge tank, increases or decreases the amount of auxiliary combustion supply according to the level, and maintains the level of dried sludge at a predetermined level. Sludge incinerator.