JPH11314100A - Method for adjusting water content of sludge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve granulation by a method in which when the water content of a mixture of dewatered sludge and dried sludge to be charged to a granulating drier is adjusted, the mixing ratio between dewatered sludge granules and dried sludge granules is adjusted so that the temperature of dry exhaust gas generated from the granulating drier is within a specified range. SOLUTION: In the treatment of sewage, dewatered sludge at least 75% in water content which was obtained by dewatering organic sludge produced in the treatment of excrement and others and has been stored in a sludge storing tank 1 is supplied to a granulating drier 4 in which a heating medium oil is circulated through a sludge mixer 3 and an oil heater 6 (as required an oil cooler 7) by a sludge pump 2. The sludge is granulated and dried to be 10% or below in water content and 2-5 mm in average particle size in the granulating drier 4. Next, the dry sludge granules are removed from the bottom part of the granulating drier 4, and most of them are stored in a dry sludge storing tank 10, but part of them are is sent to the mixer 3 to be mixed with dewatered sludge, and the amount of the dry sludge granules to be mixed is controlled so that the temperature of dry exhaust gas is 105-115 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for adjusting water content of sludge, and more particularly, to dewatering, granulation drying and carbonization of organic sludge generated in sewage treatment, night soil treatment, etc., and reused as horticultural soil and fuel. In the method of recycling sludge, the dewatered sludge is mixed with the dried sludge particles obtained by the granulation dryer in order to economically and efficiently granulate and dry the dewatered sludge, and then put into a granulation dryer. The present invention relates to a method for adjusting the water content of sludge to be produced.

[0002]

2. Description of the Related Art Conventionally, when granulating and drying dehydrated sludge, the dewatered sludge and the dried sludge obtained by the granulation dryer are used in a stage prior to the introduction into a granulation dryer. The granules are mixed with the granules, and the dehydrated sludge is applied to the surface of the dried sludge particles as a nucleus to form sludge particles having a large particle diameter. Dry sludge granules having an appropriate particle size were formed.

However, since the properties of the dewatered sludge vary depending on the moisture fluctuation of the dewatered sludge, it becomes difficult to apply the dewatered sludge to the surface of the dried sludge particles. In other words, when the water content of the dewatered sludge is large, the application of the dewatered sludge to the surface of the dried sludge particles is performed uniformly over the entire circumference only by using a small amount of the dewatered sludge with respect to the amount of the dried sludge particles. When the water content of the sludge is small, the application of the dewatered sludge to the surface of the dried sludge cannot be performed uniformly over the entire circumference unless a large amount of the dewatered sludge is used with respect to the amount of the dried sludge particles. Unless the dewatered sludge is applied to the surface of the dried sludge particles uniformly over the entire circumference, there is a problem that the granulation in a granulation dryer is reduced. Further, there is a problem in that stable operation of the granulation dryer becomes difficult due to fluctuations in the water content of the sludge fed into the granulation dryer.

In order to solve such a problem, a method of continuously measuring the water content of the dewatered sludge and adjusting the mixing ratio between the dewatered sludge and the dried sludge particles based on the measured water content is considered. However, in practice, it is difficult to continuously measure the water content of the dewatered sludge, and moreover, there is a problem that the equipment used for such measurement is expensive and the equipment cost is high.

An object of the present invention is to solve the above-mentioned problems and to provide a method for adjusting the water content of sludge which is excellent in granulating properties in a granulating dryer and which can be easily implemented with low equipment cost. It is in.

[0006]

Means for Solving the Problems and Effects of the Invention According to the method for adjusting the water content of sludge according to the present invention, the dewatered sludge is mixed with the dried sludge particles obtained by the granulation dryer, and the mixture is supplied to the granulation dryer. A method for adjusting the moisture content of the sludge to be dried, and measuring the temperature of the dried exhaust gas generated from the granulation dryer, and mixing the dehydrated sludge and the dried sludge particles so that the measured temperature becomes 105 to 115 ° C. It is characterized by adjusting the ratio.

In the method for adjusting the water content of sludge according to the present invention,
By measuring the temperature of the drying exhaust gas generated from the granulation dryer, the moisture content of the dewatered sludge can be known. That is, since the amount of sludge supplied to the granulation dryer is constant, it can be seen that when the temperature of the drying exhaust gas is high, the moisture content of the dewatered sludge of the sludge supplied to the granulation dryer is small. , On the contrary, if the temperature of the drying exhaust gas is low,
It can be seen that the moisture content of the dewatered sludge among the sludges fed into the granulation dryer is large. As a result, by measuring the temperature of the dried exhaust gas, the moisture of the dewatered sludge can be known, and thereby the fluctuation of the water content of the dewatered sludge can be grasped.
Then, when the mixing ratio between the dewatered sludge and the dried sludge particles is adjusted so that the temperature of the dried exhaust gas becomes 105 to 115 ° C,
The mixing ratio of the two can be set to a value such that the dewatered sludge can be uniformly applied to the entire surface of the dried sludge particles as a core. Therefore, the granulating property in the granulating dryer becomes excellent. In addition, the measurement of the temperature of the drying exhaust gas of the granulation dryer can be performed more easily than the measurement of the water content of the dewatered sludge, and the equipment to be used is inexpensive and the equipment cost is reduced. Furthermore, the water content of the sludge fed into the granulation dryer can be made constant, and the granulation dryer can be operated stably.

In the method for adjusting the moisture content of sludge according to the present invention, the mixing ratio of dehydrated sludge and dried sludge particles is adjusted by adjusting the amount of dried sludge particles and / or by adjusting the amount of dehydrated sludge. It may be done by one or the other. In any case, the amount of dewatered sludge with respect to the amount of dry sludge particles can be adjusted.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described.
This will be described with reference to the drawings.

FIG. 1 shows a method of granulating and drying sludge to which the method for adjusting the water content of sludge according to the present invention is applied.

In FIG. 1, an organic sludge produced by sewage treatment, night soil treatment, etc. is subjected to a dehydration treatment, and the dewatered sludge having a water content of 75% or more stored in a sludge storage tank (1) is supplied to a sludge pump.
It is sent to a granulation dryer (4) through a sludge mixer (3) according to (2), where it is granulated and dried so that the water content is 10% or less and the average particle size is 2 to 5 mm. Granulation dryer
In (4), a granulating dryer (4) →
Oil heater (6) (oil cooler (7) if necessary) →
Heat medium oil is circulated in the order of the granulating dryer (4). In addition,
This oil circulation line is provided with an expansion tank (8). The dried sludge particles are withdrawn from the bottom of the granulator / dryer (4), pass through a separation hopper (9), and most of it is a dried product storage tank (10).
Stored in Part of the dried sludge is separated hopper (9)
From the conveyer (11) to a sludge mixer (3) where it is mixed with dewatered sludge.

As the sludge is dried in the granulation dryer (4), a dry exhaust gas containing steam as a main component is generated. Therefore, the temperature of the dry exhaust gas is continuously or intermittently measured by an exhaust gas temperature measuring device (12). Measurement. Exhaust gas temperature measuring instrument
(12), Sludge pump (2) drive motor (2a) and conveyor
The drive motor (11a) of (11) is a motor control device (13)
It is connected to the. The motor control device (13) outputs at least one of the two drive motors (2a) (11a) so that the temperature measured by the exhaust gas temperature measuring device (12) falls within the range of 105 to 115 ° C. By controlling
The mixing ratio of the dewatered sludge and the dried sludge fed into the sludge mixer (3) is adjusted. For example, the mixing ratio is adjusted by adjusting the amount of dry sludge particles while keeping the amount of dehydrated sludge fed into the sludge mixer (3) constant. Further, for example, the mixing ratio is adjusted by adjusting the amount of dewatered sludge while keeping the amount of dry sludge particles fed into the sludge mixer (3) constant. Then, the sludge mixing machine
In (3), the dehydrated sludge is uniformly applied to the surface of the dried sludge particles as a nucleus over the entire circumference, and as a result, the granulation in the granulating dryer (4) is excellent.

The drying exhaust gas from the granulation dryer (4) is sent from the top of the granulation dryer (4) to the exhaust gas cooling tower (14), where cooling water is sprayed from the top in the exhaust gas cooling tower (14). Then, the drying exhaust gas is cooled. After cooling, the drying exhaust gas is sent to an oil heater (6), where it is burned and used as a heat source. The cooling water sprayed in the cooling tower (14) is sent to the treatment facility.

[Brief description of the drawings]

FIG. 1 is a flow sheet showing a method for granulating and drying sludge to which a method for adjusting water content of sludge according to the present invention is applied.

[Explanation of symbols]

 (4): Granulation dryer (12): Exhaust gas temperature measuring device

Claims (3)

[Claims] 1. A method for adjusting the water content of sludge fed into a granulation dryer by mixing dehydrated sludge and dried sludge particles obtained by a granulation dryer, wherein the method comprises the steps of: The temperature of the dried exhaust gas was measured, and the measured temperature was 10
A method for adjusting the water content of sludge, wherein the mixing ratio of dewatered sludge and dried sludge particles is adjusted so as to be 5 to 115 ° C. 2. The method according to claim 1, wherein the mixing ratio between the dewatered sludge and the dried sludge is adjusted by adjusting the amount of the dried sludge.
The method for adjusting the water content of the sludge described in the above. 3. The method for adjusting the water content of sludge according to claim 1, wherein the mixing ratio of the dewatered sludge and the dried sludge particles is adjusted by adjusting the amount of the dewatered sludge.