JPS6082198A - Heat dehydration method of sludge - Google Patents

Abstract

PURPOSE:To dehydrate easily and economically sludge with small energy consumption by heating primarily dehydrated cake with a heat treating device then supplying the cake in the state of the high temp. to a secondary dehydrating device in succession thereto and subjecting again the cake to a dehydration treatment. CONSTITUTION:The thickened sludge 1 charged through an inlet 5 is delivered into a filter cloth belt 10 by passing through a sludge mixing tank 6 and a sludge pool 7. The sludge is sandwiched between filter cloth belts 10 and 11 and is fed to a belt compression zone 12 where the sludge is compressed and dehydrated. The primarily dehydrated cake 2 contg. about 80% water is dripped between heating rollers 14 and heating jacket plates 15 constituting a heater (C) and is heated approximately to 70 deg.C while the cake falls between the rollers 14 and the plates 15. The heated and primarily dehydrated cake 3 is discharged into the spacing between a press rotor 19 of a secondary dehydrator 16 and an endless tracked filter cloth 18 and is compressed and dehydrated by the turning thereof, by which secondarily dehydrated cake contg. 50% water is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method for treating sludge discharged from sewage treatment facilities and the like.

In recent years, with the spread of sewage systems, the amount of sludge discharged from sewage treatment facilities has increased rapidly, and various problems have arisen regarding its treatment. In other words, most of the discharged sludge is simply dehydrated and then disposed of in a landfill, which causes many troublesome problems such as environmental pollution, subsequent use of the landfill, and securing land for the landfill. ing.

On the other hand, as an alternative to landfill treatment of sludge cake, there are methods such as incinerating the sludge cake after dehydration using a fluidized bed furnace or multistage furnace, or incinerating the concentrated sludge that has been discharged.
A treatment method has been developed in which water is heated to a high temperature of around 70°C to dehydrate it and then incinerated. for example,
If 100 Ton of thickened sludge is incinerated, the combustion residue will be approximately 1T0n, and its volume will be reduced to ↑Kuga'/100.As a result, not only will the required landfill area be reduced, but the sludge will be completely mineralized. This is extremely advantageous as it does not cause problems regarding land use or environmental pollution.

In the former case, the concentrated sludge (approximately 97% water content) discharged from sewage treatment facilities is dehydrated using a dehydrator to form a dehydrated cake with a water content of 75 to 80%, and then the fluidized sludge is dehydrated. This is incinerated using a furnace or the like.

However, in order to incinerate the dehydrated cake having a water content of 75 to 80% as it is, a large amount of auxiliary combustion is required, which raises the problem of extremely high processing costs.

In addition, a method has been adopted in which the dehydrated cake is not directly incinerated, but is pre-dried and then self-combusted in an incinerator, but if the moisture content of the dehydrated cake is 70 to 80%, the absolute amount of heat is insufficient in any case. However, it requires a considerable amount of auxiliary combustion with oil, etc.

On the other hand, in the latter so-called sludge heat treatment method, concentrated sludge (water content approximately 97%
) to a temperature of about 160-175°C to dehydrate it,
Furthermore, this sludge is dehydrated by a dehydrator, and the water content is approximately 50%.
Ueko'A1 is incinerated as a dehydrated cake.

However, when thickened sludge with a moisture content of 97% is heated to about 160°C
In order to heat to a temperature of 75℃, a considerable amount of heat is required, and around the reactor, there are a first heat exchanger, a second heat exchanger, an evaporator, a heat treatment thick sludge tank, and a heat treatment sludge storage tank. This method requires a filter press type dehydrator and the like, making the processing equipment complicated and making it difficult to reduce equipment costs and operating costs.

The present invention aims to solve the above-mentioned problems in the conventional sludge incineration process, and dewaters sludge in the simplest and most economical way with less energy consumption.
The purpose of this invention is to provide a method for heating and dewatering sludge that enables a significant reduction in sludge incineration processing costs.

By the way, in the incineration treatment of sludge, the factor most closely related to the economic efficiency is the dewatering rate of the sludge.

Sludge is generally composed of organic matter and inorganic matter, with organic matter usually accounting for 50 to 80%. In addition, the organic and inorganic substances in the 11,7 mud are in the form of a colloid with a grain diameter of 1 to 0.001 μm, which has an extremely strong affinity for water. It exhibits an enclosed gel structure. As a result, it becomes extremely difficult to separate the particles from water, making it difficult to perform economical dehydration using only a dehydrator.

On the other hand, when sludge is heated, the particles in the sludge become coarse due to thermal deformation of the proteins in the sludge, similar to the phenomenon in which egg white solidifies when heated, and the gel structure is destroyed by heating, causing the sludge particles to become coarse. This makes it easier for the water that was surrounded by the water to come out, resulting in a marked improvement in dehydration performance.

After repeated analysis of various combinations of sludge and heat treatment temperature conditions, the authors discovered the simplest and most economical method for heating and dehydrating sludge when incinerating sludge.

What is the claimed invention? 'j Thickened sludge discharged from water treatment facilities, etc. is first dehydrated using a primary dehydrator to reduce its weight, and then the dehydrated cake from the primary dehydrator is heat-treated using a heating device to remove the gel-like structure of the mud. The basic structure of the invention is to destroy the sludge and lower the viscosity of the sludge, and further dewater the primary dewatered cake in the high temperature, low viscosity state using a secondary dehydrator.

Hereinafter, the present invention will be explained in detail based on FIGS. 1 and 2.

FIG. 1 is a treatment system diagram of the sludge heating dehydration method according to the present invention, in which the thickened sludge 1 discharged from water treatment facility No. The water content of the thickened sludge 1 is about 97%, and the water content of the primary dehydrated cake 2 that has been dehydrated using a belt press type dehydrator or the like decreases to about 80%. Thickened sludge 1 has 97 to
n and solid content 3L l) + 1, and the components of the primary dehydrated cake 2 after the -stage dehydration treatment are solid content 3L + 1.
LOll, moisture 12, Lon, total weight is approximately 15
It becomes Lon.

The primary dehydrated cake 2 that has been subjected to the dehydration treatment is subsequently transferred to a heat treatment device C, where it is heated to a temperature of approximately 60°C to 90°C. For example, when primary dehydrated cake 2 with a water content of about 80% is heated to about 70°C, the gel structure of mud 6, which had a perfect gelatinous state at low temperatures, is almost completely destroyed, and - The viscosity of the dehydrated cake 2 is significantly reduced.

The heating temperature of the secondary dehydration cage 2 needs to be approximately 60°C or higher; if the temperature is lower than that, the gel structure of the sludge will not be sufficiently destroyed, and as a result, the water trapped between the sludge particles will be removed. The release becomes insufficient, making it extremely difficult to improve the dehydration rate in the secondary dehydration process.

The high-temperature primary dehydrated cake 3 heated to a temperature of approximately 60° C. to 90° C. in the heat treatment device C is then sent to the secondary dehydration treatment device while maintaining the high temperature state, where it is further dehydrated. For example, water content 80% heated to approximately 70°C
% primary dehydrated cake 3 can be easily dehydrated to a water content of about 50% using a caterpillar press dehydrator or the like, and the total weight of the secondary dehydrated cake 4 is 6 tons.
(Moisture 3 [On, solid content 3 ron).

Secondary dehydration cake 4 discharged from secondary dehydration treatment bag cID
As mentioned above, since the water content has been reduced to about 50%, high-temperature self-combustion is possible even in stoker furnaces, and a considerable amount of heat can be recovered, making it possible to generate electricity by sludge incineration. can.

FIG. 2 is a longitudinal cross-sectional view of the sludge heating and dewatering equipment used in the implementation of the present invention. , 9 is a belt press-type secondary dehydrator, 10° 11 is a compression furnace cloth belt, 12 is a belt compression zone, 13 is a P cloth cleaning device, 1
4 is a heating roller, 15 is a heating jacket plate, 16
17 is a caterpillar press type secondary dehydrator, 118 is a caterpillar furnace cloth, 19 is a rotor, 20
21 is a rotary cloth, 21 is a drain port, and 22 is an outlet for the secondary dewatering cake.

The thickened sludge 1 introduced from the inlet 5 is mixed with sludge 4311
5 and sludge pool 7 onto the P fabric belt 1°, and is sent to the belt compression zone 12 while being sandwiched between the F fabric belts 10 and 11, where it is compressed and dewatered. Moisture content in belt compression zone 12 is 80
The primary dehydrated cake 2, which has been dehydrated to approximately
While falling through the gap, it is heated to about 7oC. The heated high-temperature primary dehydration cake 3 is then sent to the secondary dehydration machine 16.
is discharged between the press rotor 19 and the caterpillar F cloth 18, and after being compressed and dehydrated by the rotation of the caterpillar 17 and rotor 19, it becomes a secondary dehydrated cake 4 with a water content of approximately 50% and is delivered to the cake outlet 22. more excreted.

In the present invention, as described above, the concentrated sludge 1 is dehydrated in the primary dehydration treatment device B, and the dehydrated cake 2 is then transferred to the heating device C.
After heating to 60℃~90℃.

Since the water is dehydrated in the secondary dehydration treatment bag UD, it can exhibit many excellent effects.

First, after the concentrated sludge 1 is subjected to primary dehydration treatment, the secondary dehydration cake 2 is heated, so that the heat required for heating can be significantly reduced. For example, if the concentrated sludge (moisture 97%) 1 is 100 tons, the total 1-11 of the secondary dehydration cake (moisture 80%) 2 is 15Lon, and the amount of heat required to heat this to 70℃ is approximately 9QQ,
QQQ Kcal (15X 103u/, X (7
O-10)°C). On the other hand, 100 tons
When directly heating the thickened sludge 1 to 70℃, approximately 6
．． 000,000Kcal (100X 10"J'/
The amount of heat required for heating can be reduced to about 1/6.7 by performing subsequent water treatment.

In addition, - dehydrated cake (moisture 80%, total weight 15ron)
) 2 to 70° C. and then perform a secondary dehydration treatment to obtain the secondary dehydrated cake 4 with a water content of 50%, the required amount of heat is approximately 900.000 Kcal as described above. On the other hand, if the water content of the primary dehydrated cake 2 (80% moisture, total amount 15 on) is evaporated by the conventional heating drying method and the water content is 50%, 9
It is necessary to evaporate the moisture of LOn (12t-3L'), and the amount of heat required is approximately s, 940.000
Kcal (9000'P x 600 ""l/EP
+(3000+3000) Ky7cx(100
-1.0)°C), which means that approximately 6.6 times as much heat is required as compared to the present invention.

As described above, in the present invention, by combining primary dehydration, heating, and secondary dehydration, the hot time required for dehydration is smaller than any other conventional dehydration method, and it has excellent thermoeconomic efficiency. It is.

Furthermore, in the present invention, the primary dehydration cake after the secondary water treatment is heated to 60°C to 90°C to destroy its gel structure, and at the same time, the secondary dehydration is carried out at a high temperature of approximately 60°C to 90°C. As a result, the viscosity of the sludge is significantly reduced, making it easy to separate water and solids, and the moisture content of the dehydrated cake can be reduced to approximately 50% using a regular caterpillar press type dehydrator. It can be reduced to a certain extent.

Moreover, in the present invention, the heated -sub-dehydrated cake has a high Wu
Because it is filtered as it is for secondary dehydration treatment,
It is naturally desirable for the processing equipment itself to have a configuration that integrates the primary dehydrator, heater, and secondary dehydrator, and as a result, the processing equipment can be made extremely compact, resulting in a significant reduction in equipment costs. becomes possible.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of the heating dehydration treatment of sludge according to the present invention. FIG. 2 is a longitudinal cross-sectional view of a sludge heating dehydration treatment apparatus used in the implementation of the present invention. 13 - Secondary water treatment device C Heat treatment device D Secondary dehydration treatment device 1 Concentrated sludge secondary dehydration cake 3 High temperature secondary dehydration cake 4 Secondary dehydration cake Patent applicant Tarima Co., Ltd. Representative Fuku 1) Order Kichi

Claims (1)

[Claims] Sludge (1) discharged from a sewage treatment facility (Δ), etc. is first dehydrated in a primary dehydration treatment device (B), and then the primary dehydration cake (2) whose weight has been reduced through the dehydration treatment is transferred to a heat treatment device (C). ), and the primary dehydration cake (3), whose temperature has been raised by heating, is then supplied to the secondary dehydration treatment device (D) while still at high temperature, and is subjected to m-degree dehydration treatment. dog .