JPH0771676B2 - Pumping method of dehydrated sludge in sludge treatment equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention incinerates dehydrated sludge (dehydrated cake) whose main component is protein, which is obtained by dehydrating sewage sludge generated from a sludge treatment facility such as a sewage treatment plant. The present invention relates to a method for pumping dewatered sludge in a sludge treatment facility used to transfer it to the next process such as equipment.

(Prior art) In a sewage treatment plant, etc., after inflowing sludge is treated with activated sludge, dehydrated sludge (dehydrated cake) obtained by dewatering excess sludge, initial sludge, mixed raw sludge, etc.
It is carried out by transferring it to an incinerator such as an incinerator by a conveyor or the like, incinerating it, and disposing as incinerated ash. However, when the dehydrated cake was transferred by a conveyor, some of the dehydrated cake might be scattered and dropped on the way to worsen the environment, and the conveyor had not a closed structure, so odor countermeasures were necessary. .

For this reason, a pumping method for pumping the dehydrated sludge to the incinerator by a pump has been studied. However, the dehydrated sludge has a high viscosity, and the sludge dewatering treatment facility and the incinerator are separated by several tens to several hundred meters. However, there is a problem in that the pressure loss in the sludge pumping pipe becomes extremely large, and the load on the rotor and the stator of the pump component becomes excessively large, which easily causes a failure due to wear or damage.

(Problems to be Solved by the Invention) The present invention solves such conventional problems and smoothly pumps highly viscous dewatered sludge obtained by dewatering sewage sludge to the next step such as incineration equipment. It was completed for the purpose of the method of pumping dewatered sludge in a sludge treatment facility that can be pumped by.

(Means for Solving the Problem) The above-mentioned problem is pressure-fed when pumping a highly viscous dewatered sludge whose main component is protein, which is obtained by dehydrating sewage sludge generated from sludge treatment equipment, to the next process. A method of pumping dehydrated sludge in a sludge treatment facility, characterized in that the dehydrated sludge is heated to a temperature of 90 ° C. or lower to modify the protein and pressure-fed while reducing the pressure loss in the pipe. You can

(Example) Next, the present invention will be described in more detail with reference to the drawings.
In FIG. 1, (1) is a sludge storage tank for storing dehydrated sludge whose main component is protein obtained by dehydrating sewage sludge generated from sludge treatment equipment, and (2) is several tens to several hundreds of meters. It is an incinerator such as an incinerator installed at a remote place. (3) is a pump for pumping the dehydrated sludge from the sludge storage tank (1) to the incinerator (2), and (4) is a pipe for pumping sludge. As the pump (3), it is preferable to use a rotary displacement type uniaxial eccentric screw pump. This type of pump is capable of continuously pumping sludge by rotating a screw-shaped rotor having a perfect circular cross section inside a stator having an oval cross section.

In this embodiment, a heating means (5) for the dehydrated sludge is provided between the sludge storage tank (1) and the pump (3). For example, a paddle dryer or the like is used as the heating means (5). Dehydrated sludge contains a large amount of organic substances, especially proteins, and is heated to a temperature of 90 ° C. or less while passing through the inside thereof, so that the quality of proteins is altered. That is, the gel structure of the hydrogel containing protein is thermally decomposed, a so-called syneresis phenomenon occurs in which the water contained therein is separated, the viscosity is reduced, and the sludge can be easily supplied to the cooling equipment.

(6) is a waste heat recovery device that recovers heat from the high temperature gas of the incineration facility (2). In the embodiment, the recovered heat is heated as steam or hot water through the waste heat circulation line (7) for heating means ( 5) is supplied. However, the heat source of the heating means (5) is not limited to this, and any heat source can be used.

In the present invention, the heating means for the dehydrated sludge (a part or the whole of the pipe (4) for guiding the dehydrated sludge whose main component is protein discharged from the pump (3) to the next step such as incineration equipment ( 9) is provided. As described above, when the dehydrated sludge whose main component is protein is heated to a temperature of 90 ° C. or lower, the viscosity decreases due to syneresis and the sludge can be easily supplied to the incinerator. If the heating temperature of the dehydrated sludge exceeds 90 ° C, the protein in the organic matter will solidify, and if it is cooled and solidified in the middle of the piping, the fluidity will not recover even if it is reheated at startup. , It becomes difficult to restart. Therefore, in the present invention, the heating temperature of the dehydrated sludge is set to 90 ° C or lower.

In the embodiment, heat is supplied to the heating means (9) through the waste heat circulation line (8), and the dehydrated sludge that is pressure-fed is maintained at a temperature of 90 ° C. or lower. Also in this case, the heat source of the heating means (9) is not limited to waste heat, an independent heat source such as an electric heater can be used, and steam can be blown directly into the dehydrated sludge. You can also do it. Needless to say, the heating means (5) and the heating means (9) may be used alone or in combination as in the embodiment.

FIG. 2 is a graph showing a decrease in pipe pressure loss when the dehydrated sludge is pumped by the method of the present invention. This data shows that polymer coagulant was added to mixed raw sludge with sludge concentration of 3%.
Dehydrated sludge containing 5-80% of cake water obtained by adding 5% and dehydration treatment is heated to a temperature of 90 ° C or less, and is horizontally leveled at a flow rate of 1 ton / hr through a pipe of 100A with a uniaxial eccentric screw pump. This is the data when pumping 11m.

As shown in the graph of FIG. 2, the pressure loss in the pipe (4) sharply drops due to heating. It is considered that this is because the protein, which is the main component of the dehydrated sludge, is deteriorated by heating as described above, and the dehydrated sludge can be pumped very smoothly. Note that even if the temperature of the dehydrated sludge exceeds 90 ° C, the decrease in pressure loss will be slight, and it will be difficult to restart when it has been cooled and solidified in the middle of the pipe as described above, so heating at 90 The temperature shall be below ℃. In order to suppress the pressure loss of the pipe to several Kg / cm ² or less, it is more preferable to heat the dehydrated sludge at a temperature of 40 to 80 ° C., though it depends on the water content and properties of the dehydrated sludge. Further, as described above, the same effect can be obtained by directly blowing steam into the dehydrated sludge.

(Operation) According to the present invention, the dehydrated sludge whose main component is protein in the sludge storage tank (1) is heated to a temperature of 90 ° C. or lower by the heating means (5), or one of the pipes (4) While heating a part or the whole to a temperature of 90 ° C. or lower by a heating means (9), the dehydrated sludge is pressure-fed by a pump (3) to tens to hundreds of meters.
Incinerate in a separate incinerator (2). Since the dehydrated sludge is heated to a temperature of 90 ° C. or lower, more preferably 40 to 80 ° C. by the waste heat of the incineration facility (2), the viscosity becomes small due to the alteration of the protein as described above, The pressure loss in the pipe (4) can be significantly reduced as compared with the conventional case. As a result, not only was the power of the pump (3) reduced to 70-80% of the conventional one, but the life of the stator and rotor of the pump (3) was conventionally 2000-3000 hours and 6000-9000 hours. According to the present invention, it was possible to double the time by 4000 to 6000 hours and 12000 to 18000 hours, respectively.

Further, if the dehydrated sludge is heated by the waste heat of the incineration facility as in the embodiment, the thermal efficiency of the entire sludge treatment facility and the incineration facility can be improved.

(Effect of the invention) As is apparent from the above description, the present invention is capable of pumping highly viscous dewatered sludge whose main component is protein to the next process such as incineration equipment at low pressure, resulting in pressure loss. The pump power required for the pressure feeding can be reduced, and the pressure feeding can be performed over a longer distance than in the past. Further, according to the present invention, it is possible to reduce the breakdown of the devices used for pumping, reduce the maintenance cost, and improve the thermal efficiency and operating rate of the entire facility. Furthermore, since the transfer route of the dehydrated sludge can be made into a sealed structure, it becomes easy to prevent the warmed sludge from deodorizing. Therefore, the present invention is extremely large in that it contributes to the development of industry by eliminating the conventional problems.

[Brief description of drawings]

FIG. 1 is a piping system diagram showing an embodiment of the present invention, and FIG. 2 is a graph showing the relationship between the temperature of the dehydrated sludge pumped and the pressure loss in the pipe. (1): Sludge storage tank, (2): Incinerator, (3): Pump, (4): Pipe, (5): Heating means, (6): Waste heat recovery device, (7), (8) ): Waste heat circulation line, (9): Heating means

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Claims (1)

[Claims] 1. When pumping a highly viscous dehydrated sludge, whose main component is protein, which is obtained by dehydrating sewage sludge generated from sludge treatment equipment, to the next step by pump, A method for pumping dewatered sludge in a sludge treatment facility, characterized in that the protein is denatured by being heated to a temperature, and the pressure loss in the pipe is reduced while pressure-feeding.