JPS58163498A - Thickener for sewage sludge - Google Patents

Abstract

PURPOSE:To efficiently concentrate sewage sludge having a high water-retaining ratio, by providing a few heating-dehydrating units at a pipe for supplying sewage sludge provided at the central part, and providing a jacket chamber having a heat-transmitting wall at one side of the supply passage to each of the heating-dehydrating units. CONSTITUTION:Pressure in the jacket chamber 43-3 of the third unit u3 can be made equal to that in the jacket chamber 45-2 of the second unit u2 to hold negative pressure at 0.5kg/cm<2> and the temp. of evaporation at about 80 deg.C. Pressure in the jacket chamber 43-2 of the second unit u2 can be made equal to that in the jacket chamber 45-1 of the first unit u1 to hold negative pressure at 0.2kg/ cm<2> and the temp. of evaporation at about 60 deg.C. Pressure in the jacket chamber 43-1 of the first unit u1 can be made at 0.1kg/cm<2>, so that the temp. of evaporation can be hold at about 40 deg.C. Accordingly, the water-retaining ratio of supplied sewage sludge can be lowered from 80% to a value below 60%.

Description

DETAILED DESCRIPTION OF THE INVENTION When treating sewage sludge, it is important to remove water in the first step. Sewage sludge can be concentrated to a moisture content of 80% to 60% by mechanical treatment, but if the sewage sludge is further heated to evaporate the water and concentrated to a moisture content of 60% to 50%, subsequent treatment can be performed. It can be done very easily and smoothly.

The present invention relates to a concentrating device that is effective in treating sewage sludge with a relatively high moisture content of about 80 inches.

The present inventor has previously developed a sewage sludge incinerator shown in FIG. The present inventor has also previously developed a heating dehydrator shown in FIGS. 2 and 3, which is used in place of the heater 3 of the sewage sludge incinerator shown in FIG.

The present invention is a sewage sludge thickening device used in the sewage sludge incinerator shown in FIG. 1, and the heating dehydrator shown in FIGS. 2 and 3 will be explained before explaining the present invention.

The present invention uses two to four heating dehydration units for sewage sludge,
In other words, by arranging multiple units in series in the sewage sludge supply path, with the first unit at the lowest pressure and the last unit at the highest pressure and connected back and forth, the sewage sludge is concentrated to an increasingly high concentration. This is what made it possible.

In Fig. 1, sewage sludge with a moisture content of about 80% in a hollow tank 1 is heated by a feeding means 2 through a sewage sludge heater 3, and the temperature is raised to form a sewage sludge having a fluidized sand bed. It is supplied to the drying oven 4. The drying furnace is supplied with the required amount of drying gas heated to 200°C to 400°C from the space below the sand bed, and this gas fluidizes the sand bed, so that the supplied sewage sludge is pulverized by this fluidized sand bed. It is dried while being washed. The product produced in the drying oven 4 is sucked by a blower 11 and separated into a solid component and a gas component by a separating means 5. The solids are dropped into a hopper provided below the separation means 5, and are supplied in constant amounts to the sewage sludge combustion furnace 1 by a powder supply means 6 provided at the bottom of the conch. Figure 1 shows that this combustion furnace has a two-stage combustion system consisting of an incomplete combustion furnace T and a complete combustion furnace T'. It can be significantly reduced. The air necessary for these combustions is first delivered to the outside of the complete combustion furnace γ' by a blower 13.
After being preheated through an air preheater 14 provided in the air preheater 14, the air is divided and supplied to the incomplete combustion furnace T and the complete combustion furnace 1'. The products of the complete combustion furnace 7' are sucked in by a blower 10, passed through a heat exchanger 8, passed through a filter 9, and then passed through a blower 10.
Smoke is removed by Further, the gas separated by the separation means 5 is pressurized by a blower 11 and circulated by a circulation pipe 12, and the heat exchanger 8 is provided in the circulation path, and the temperature is increased from 200°C to 400°C by the heat exchanger.
The temperature is raised to The amount of gas heated by the heat exchanger 8 is the sum of the amount A of gas supplied to the drying furnace 4 for drying and the amount B of gas generated from the sewage sludge supplied in the drying furnace 4. Quantity is ant, A of these total amounts
The same amount of gas as B is again supplied to the drying oven 4 as a necessary drying gas amount, and the remaining gas amount, which is exactly the same as B, is supplied to the heater 3 as a heating gas amount. The heater 3
The gas after heating the sewage sludge passes through the drain separation means 15 and is discharged from the system by the drain separation means, and then is supplied to the combustion furnace 1 through the gas supply pipe 16. Most of the sewage sludge generated by the drying furnace 4 is steam, and by passing the water vapor through the heater and draining it out of the system, the residual gas is supplied to the combustion furnace, so that it is combusted. A feature of this incineration system is that it can reduce the amount of boiling water in the furnace.

This sewage sludge incinerator has 350 calories from sewage sludge with a relatively high moisture content or dried sewage sludge solids.
It is an incineration system that is suitable for incinerating low-calorie sewage sludge with 0 Kcal or less of 1 kg, and can perform incineration smoothly using only its own calories, almost eliminating the need to replenish the incineration tank with fuel.

However, it is desirable that the amount of water supplied into the combustion furnace T be even smaller, so instead of the heater 3, a heating dehydrator with a function that can discharge as much of the water contained in the sewage sludge as possible out of the system. The adoption of was studied.

Figures 2 and 3 show a heating dehydrator which the present inventor has already adopted in place of the sewage sludge heater in Figure 1.

In the heating dehydrator shown in FIGS. 2 and 3, air permeable porous walls 22, 23 are provided at the upper and lower parts of the sewage sludge supply channel 21, and mantle chambers 24, 25 are provided outside these porous walls, respectively, and heating is performed. A switching valve 27 is provided in the gas supply pipe 26, and the switching valve 2T
One downstream branch pipe 28 communicates with one mantle chamber 24 , and the other branch pipe 29 communicates with the other mantle room 25 . Also, the discharge pipe 30 of the mantle chamber 24 and the discharge pipe 3 of the mantle chamber 25
1 are all communicated with a switching valve 32, and a bachium starch 34 is provided in a discharge pipe 33 downstream of the switching valve 32, and
The two switching valves 27 and 32 have a structure in which switching is performed in conjunction with each other at regular intervals.

In this sewage sludge heating dehydrator, the switching valves 27 and 32 are switched in conjunction with each other at regular intervals, so that the heating gas is sucked by the pachyumponzo 34 and first enters one of the mantle chambers to supply sewage sludge. Cross the pipe 21 and enter any other mantle chamber, discharge pipe 33, pachium pump 34,
After passing through the drain separation means 15 and separating the drain, the combustible gas component is supplied to the combustion furnace T through a supply pipe 16.

However, this heating dehydrator requires two interlocking switching valves 27 and 32, and is of a type in which the heating gas is blown directly into the sewage sludge.

Figures 4 and 5 show a heating dehydration unit in which sewage (sludge) is indirectly heated by passing through a heat conductive metal plate without using a switching valve.The present invention uses several of these heating dehydration units. First, however, the heating dehydration unit will be explained.

41 is a sewage sludge supply route. In Fig. 4, the sewage sludge advances from left to right as shown by the arrow, and there is a feeding means 2 on the left side, such as a screw type extruder, for forcibly discharging the sewage sludge, and the sewage sludge flows on the right side. It has a sewage sludge drying furnace 4 having a sand bed. A heat conducting wall 42 such as a metal plate is provided on one side wall of this sewage sludge supply channel 41, and an air permeable porous wall 43 made of wire mesh or sintered metal having ventilation holes with a diameter of 2 μm to 100 μm is provided on the other side wall. A mantle chamber 44,45 is provided through each of these walls 42,43. A heating gas supply pipe 46 is connected to the mantle chamber 44 having the heat conduction wall 42 to supply high temperature heating gas. Further, a discharge pipe 47 is provided in the mantle chamber 41#, and the discharge pipe 4
7 is provided with a drain separation means 15, and the drain separation means removes the drain from the slightly cooled gas, and the residual gas is sent to the combustion furnace 7 through a sewage sludge gas supply pipe 16.
supply to The mantle chamber 45 also has a permeable porous wall 43.
A suction pipe 49 is provided in the suction pipe 49, a cooling means 50 and a drain separation means 5J are provided in the suction pipe 49, and the gas after drain is removed from the gas suctioned by the suction pipe 49 is also supplied to the sewage sludge gas supply pipe 16. transport.

This heating dehydration unit uses an indirect heating method via a metal heat conductive plate.

The sewage sludge thickening apparatus of the present invention will be explained with reference to FIG. 6, which shows an embodiment thereof.

In FIG. 6, a sewage sludge supply channel 41 is provided in the center, and three heating dehydration units U1 are connected in series to the supply channel 41.
, U2, and U3 are provided in series. Each heating dehydration unit is provided with a jacket chamber 44 having a heat conductive wall 4.2 on one side of the supply path 41, a heating gas supply pipe 46 and a discharge pipe 47 in the jacket chamber, and a heating gas supply pipe 46 and a discharge pipe 47 on the other side of the supply path 41. Breathable porous wall 43
It has a structure in which a mantle chamber 45 is provided, and a suction pipe 49 is provided in the mantle chamber to suck in the evaporated gas generated from the evaporated sewage sludge. In the thickening device of the present invention, the heating dehydration unit U having the above structure is connected to the central sewage sludge supply path 41.
About 2 to 4 of them are provided, that is, a plurality of them.
In FIG. 6, three are provided. Then, the cooling means 5 is connected to the suction pipe 49-1 of the evaporated gas of the first heating dehydration unit
0 and drain separation means 51 are provided. In addition, drain separation means 15.15'... are provided in the discharge pipes 47, 47'... of each heating dehydration unit, and the drain is extracted from the system by the drain separation means 15.15'... The remaining gas is sent as gaseous fuel to an appropriate location, for example, to the combustion furnace 7, through the sewage sludge gas supply pipe 16. The heating gas supply pipe 46-1 of the first heating dehydration unit Ul is the suction pipe 4 of the evaporated gas of the second unit U2.
9-2, the heating gas supply pipe 46-2 of the second unit U2 is connected to the evaporation gas suction pipe 49-2 of the third unit U2.
Connect with 3. Then, the heating gas supply pipe 46-3 of the third unit u3, which is the last unit, is connected to a high pressure and high temperature heating gas supply pipe.

In the concentrator shown in FIG. 6, the gas sent to the third unit for heating is pressurized to a water column of 1200 to 1500+m by the blower 11 shown in FIG.
The temperature is raised to about 250°C. The pressure in the jacket chamber 43-3 of the third unit u3 is equal to the pressure in the jacket chamber 45-2 of the second unit u2, which is a negative pressure of 0.5 #/d, and therefore the evaporation temperature can be set to about 80°C. 2nd 2nd) The pressure in the mantle chamber 43-2 of u2 is equal to the pressure in the mantle room 45-1 of the first unit ul, which is a negative pressure of 0.2 mol/crI, so the evaporation temperature can be set to about 60°C. can. 1st unit) The pressure in the mantle chamber 43-1 of ul is 0.1Af/71
177! The evaporation temperature can be set to about 40°C.

The sewage sludge thickening device of the present invention has a multi-stage heating dehydration unit, so that, for example, when the moisture content of the supplied sewage sludge is 80%, the water content of the sewage sludge after passing through the present thickening device is The ratio can be made 60- or less. In other words, the amount of sewage sludge supplied is 100 tons.
If the moisture content is 80 tons, the composition of sewage sludge at the time of supply has a solid content of 20 tons.

The water content is 80 tons. As a result of passing through this concentrator, the moisture content is 60 cm, which means that the solid content is 20 To
By setting the composition to 30 tons of water, 50 tons of water is removed by this concentrator. In this way, this concentrator can achieve a high degree of concentration, and if such a high degree of concentration is achieved at the beginning of the sewage sludge treatment process, the amount to be processed in the subsequent process will be reduced to 50 tons, and the moisture content will also be reduced. Since it is 60%, it can be processed smoothly,
This not only makes it easier to incinerate sewage sludge, but also allows recovery of various resources from sewage sludge.

FIG. 7 is a graph showing the effects of the present sewage sludge thickening device, which the inventor has compiled as a result of repeated experiments with the present thickening device.

To explain the graph in Figure 7, in the graph below, the vertical axis shows the moisture content of sewage sludge supplied to this thickening device, and the horizontal axis shows the water percentage of sewage sludge discharged from this thickening device. , the four curves each indicate that the degree of concentration differs depending on the number of heating dehydration units installed.

For example, if the supplied sewage sludge has a moisture content of 801% and the number of units is three, the moisture content of the sewage sludge discharged from this thickening device can be 57%.

In the above graph, the vertical axis shows the percentage of dry sewage sludge solids that is recovered as a heat resource in the treatment of sewage sludge. In addition, the four curves indicate that the calorie content of dried sewage sludge solids ranges from 5,000 Kcal to 2,000 Kcal.
It shows how the recovery rate of heat resources differs between KeaJ and high calorie and low calorie cases. For example, if the water content of sewage sludge discharged from a thickening device is set to 57 cm using a three-stage heating dewatering unit, the calorie content of the dry solid content of this sewage sludge is 3000 Kc.
If it is al/#, the recovery rate of this solid content as a heat resource is 06, and the above concentration can be performed with 40% of the calories of the dry solid content of the sewage sludge used. That is, when 100 tons of sewage sludge with a moisture content of 80 inches is treated every day, the calorie content of the dry solid content of this sewage sludge is 3000 KcaA! /#, the solid content of sewage sludge of 100 Tpn is 20 Ton, so 8 of it is
Ton is used in the concentration process, and 12 Ton, or 36 million Kcal, can be recovered as heat resources.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a sewage sludge incinerator previously developed by the present inventor. FIGS. 2 and 3 are a side sectional view and a sectional view taken along the line 1--2 of a sewage sludge heating dehydrator previously developed by the present inventor. FIGS. 4 and 5 are a side sectional view and a sectional view taken along the line V--2 of a sewage sludge heating dehydration unit used in the thickening apparatus of the present invention. FIG. 6 is an explanatory diagram of a sewage sludge thickening apparatus according to the present invention. FIG. 7 is a graph showing the effect of the sewage sludge thickening apparatus of the present invention. 41 is a sewage sludge supply channel, 42 is a heat conduction wall, 43 is a permeable porous wall, 44.45 is a mantle chamber, 46 is a heating gas supply pipe, and 4T is a discharge pipe. 15 is a drain separation means, 16 is a sewage sludge gas supply pipe,
49 is a suction pipe, 50 is a cooling means, 51 is a drain separation means & agent Yoshihiko Okoshi, -

Claims (1)

[Claims] A sewage sludge supply channel 41 is provided in the center, and several heating dehydration units u1, u2, etc. are provided in series with the supply channel 41, and each heating dehydration unit has a heat conductive wall on one side of the supply channel 41. 42, a heating gas supply pipe 46 and a discharge pipe 47 are provided in the mantle room 44, a mantle room 45 having an air permeable porous wall 43 is provided on the other side of the supply path 41, and the mantle room 44 is provided with a heating gas supply pipe 46 and a discharge pipe 47. 45 is provided with an evaporated gas suction pipe 49, and the evaporated gas suction pipe 49-1 of the first heating dehydration unit) U+ is provided with a cooling means 50 and a drain separation means 51,
Drain separation means 15, 15'... are provided in the discharge pipes 47, 47'... of each heating dehydration unit, and the gas separated from the drain by these drain separation means is converted into gas by the sewage sludge gas supply pipe 16. The heating gas supply pipe 46- of the 1st heating and dehydrating unit Uk is connected to the suction pipe 49 of the evaporated gas of the 1st heating and dehydrating unit Uk+1, which is the next unit. A sewage sludge concentrating device in which a heating gas supply pipe is connected to a heating gas supply pipe 46-n of the n-th heating dehydration unit (un) which is the last unit.