JPS60179492A - Conversion of organic sludge to energy - Google Patents

Abstract

PURPOSE:To speed up heat transfer in thermal cracking and produce oil consistently and quickly with a high efficiency, by adding produced oil to organic sludge and performing thermal cracking at a relatively low temp. CONSTITUTION:Dehydrated organic sludge is sent from a dehydrated sludge storage tank 11 into a drier 12 for thorough drying and is led into a thermal cracking oven 13 kept at about 150-450 deg.C for thermal cracking to produce a small amt. of incombustible gas and large amts. of oil and char. The incombustible gas is sent to a waste gas disposal process 14 and the oil is stored in an oil storage tank 15 for recovery of energy. A part of oil is mixed with dried sludge and is led into the thermal cracking oven together with sludge. The char is burned to ash in an incinerator 16 for utilization as heat source for the drier 12 and the thermal cracking oven 13. Addition of oil speeds up heat transfer, leading to uniform and quick thermal cracking to produce oil efficiently.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to biological treatment sludge discharged from sewage treatment plants, human waste treatment plants, industrial wastewater treatment plants, etc., or organic sludge such as livestock waste. The present invention relates to a method of converting a substance into energy, and particularly to a method of converting it into energy as a metal.

[Technical background of the invention]

Conventionally, in order to recover energy from organic sludge-like substances (hereinafter referred to as sludge) such as surplus activated sludge generated in sewage treatment plants, dehydrated sludge is stored in a dehydrated sludge storage tank (as shown in Figure 1). After being sent from 1) to a dryer (2) and sufficiently dried, it is introduced into a pyrolysis furnace (3) whose reaction temperature is adjusted to about 600 to 1000°C, where it is thermally decomposed to produce flammable gas and a small amount of oil and Char (decomposition residue) is generated, combustible gas is stored in a gas storage tank (4) and recovered as energy, and oil and char are generated in a dryer (2) and a pyrolysis furnace (
In order to use it as a hot wire in step 3), it is introduced into an incinerator (5) and burned.

[Problems with Background Art] In the case of this conventional method, since the form of energy recovery is flammable gas, there is a problem in that handling is troublesome in terms of storability, capacity, safety, etc.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned points and aims to recover the waste in a highly advanced form.

[Summary of the invention]

Therefore, the inventors attempted to improve the thermal decomposition method of sludge for the purpose of converting it into oil, and found that when the thermal decomposition temperature was set to a relatively low temperature range, a small amount of nonflammable gas and a large amount of nonflammable gas were extracted from the sludge. They discovered that oil and char (decomposition residue) are generated, and also focused on the poor heat transfer of sludge during thermal decomposition.Thus, the present invention was completed, and the organic sludge of the present invention The method for converting organic sludge-like substances into energy is to thermally decompose organic sludge-like substances at a relatively low temperature range of 150 to 450°C to generate a large amount of oil, and to convert the generated oil into organic sludge-like substances by thermally decomposing the oil. It is characterized in that the oil is added and used as a heat transfer medium to generate oil with high efficiency.

[Embodiments of the invention]

The method of the present invention will be explained in detail based on embodiments shown in the drawings.

As shown in Figure 2, the dehydrated sludge is stored in a dehydrated sludge storage tank a.
After being sent from η to the dryer (6) and sufficiently dried, it is introduced into the thermal decomposition furnace a3 whose reaction temperature is adjusted to about 150 to 450°C and is thermally decomposed. 1. A small amount of nonflammable gas and a large amount of oil and Char (decomposition residue) is generated.

Then, the non-flammable gas is sent to the waste gas treatment process α→, the oil is stored in the oil storage tank αQ and recovered as energy, and a part of the oil is sent from the oil storage tank α to the dried sludge and mixed. The char is impregnated and introduced into the pyrolysis furnace α purifier together with the sludge, and the char is passed through the dryer (6) and the pyrolysis furnace 0.
In order to use it as a heat source, it is introduced into an incinerator and burned into ash.

The results of an experimental example in which surplus activated sludge generated at a sewage treatment plant was subjected to thermal decomposition treatment at a temperature of 350°C and a comparative example in which thermal decomposition treatment was performed at a temperature of 800°C are shown in the first part. Shown in the table.

Table 1 From the results, it can be seen that by thermal decomposition at a relatively low temperature, (1) the oil yield is more than three times greater than the conventional heat treatment at a relatively high temperature.

■Even if the gas yield is less than half, it becomes non-flammable.

I understand that. This clearly shows that when the sludge thermal decomposition temperature is set as in the present invention, oil can be preferentially obtained as recovered energy.

Furthermore, the temperature effect of heat treatment in the low temperature range of 150 to 450°C defined in the present invention will be explained using the results of a pyrolysis experiment using a batch method (Kutsch test).

Figure 3 shows the relationship between the temperature and the amount of oil produced when the reaction was carried out at various thermal decomposition temperatures; the solid line is
The broken line shows the relationship between reaction temperature and oil production amount.
It shows the differential type of Mihi.

The broken line in Figure 3 is centered at 300°C,
It is clearly shown that the amount of oil produced is large in the temperature range of 50°C.

Next, regarding the addition of oil, which is one of the elements of the present invention, an experimental example in which sewage treatment sludge was used as a sample and oil was added in a weight ratio of 5% to dry sludge according to the process shown in Figure 2. Table 2 shows the test results of comparative examples in which no oil was added and the pyrolysis treatment time was changed.

*The value of (oil amount/dry sludge amount) does not include added oil.

This result shows that the pyrolysis time can be shortened when oil is added.

This is because the poor thermal conductivity of the dry sludge mass is improved by the addition of oil, and the oil is used as a heat transfer medium to quickly transfer heat to the sludge volume and inside the sludge mass.
This is because thermal decomposition is carried out uniformly and quickly.

The amount of oil added is determined by various conditions such as the properties of the sludge and the structure of the pyrolysis furnace. (preferably 5-50
In addition, although the basic steps of the present invention are shown in FIG. 2, this step can be varied in various ways, and other steps may be added, such as a combination of heat recovery processes. ,
Alternatively, the sludge to be thermally decomposed can be formed into predetermined granules to speed up the transfer of heat during thermal decomposition, thereby shortening the thermal decomposition reaction time and further promoting the efficiency of oil production. In order to prevent impurities from sludge powder from being mixed into the oil, ・Furthermore, by adding sludge KMm to thermally decompose the ash of the char incinerated in the incinerator aQ, Ca, AJ, It is also possible to increase the recovery rate of oil by using metal oxides and inorganic salts such as Fe, Na, etc. as catalysts for the thermal decomposition reaction of sludge.

In addition, the applicable sludge is not limited to sewage treatment sludge, but is particularly limited to biological treatment sludge from human waste treatment plants, industrial wastewater treatment plants, etc., or organic sludge-like materials such as welfare livestock waste. It's not a thing.

〔Effect of the invention〕

As described above, according to the present invention, organic sludge-like substances are thermally decomposed at a relatively low temperature range of 150 to 450°C, so energy can be used to easily handle organic sludge in the form of oil with high added value. Furthermore, since the processing temperature is low, the equipment can be made at low cost.Furthermore, since the produced oil is added to the organic sludge-like material to be thermally decomposed, heat transfer is accelerated during thermal decomposition. Otherwise, thermal decomposition is carried out uniformly and quickly, and oil is efficiently produced.

[Brief explanation of drawings]

FIG. 1 is a process diagram showing the conventional method, FIG. 2 is a process diagram showing the method of the present invention, and FIG. 3 is a diagram showing the relationship between the thermal decomposition temperature and the amount of oil produced.

Claims (1)

[Claims] (1) Organic sludge-like material is produced by thermally decomposing the organic sludge-like material at a temperature of 150 to 450°C to generate oil, and adding the generated oil to the organic sludge-like material to be thermally decomposed. Energization method.