JP4003045B2 - Dehydrating cake direct charging device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a dewatered cake charging device for supplying dehydrated cake from a sludge storage tank to an incinerator, and when the pressure in the supply pipe rises due to anaerobic fermentation of the dehydrated cake, it is circulated to the sludge storage tank via a return pipe. The present invention relates to a dehydrated cake charging device.
[0002]
[Prior art]
When sewage is treated by the activated sludge method, excess sludge generated by the primary and secondary treatments is concentrated, digested, filtered, and incinerated in a sludge incinerator. In the incinerator, a steady operation is performed at a temperature of about 800 ° C., and dehydrated cake (dehydrated sludge) is quantitatively supplied to the incinerator so as to reduce the content of NOx and the like contained in the gas released to the atmosphere. . That is, in the incinerator, the dehydrated cake is burned under a constant air supply. Therefore, if the supply amount of the dehydrated cake is less than a predetermined value, the oxygen concentration in the incineration exhaust body increases and the amount of NOx generated increases. . On the other hand, if the supply amount of the dehydrated cake is larger than the predetermined value, the oxygen concentration in the incineration exhaust body becomes low, and the amount of HCN generated increases due to the mixture of NH ₄ and CH ₄ generated in the combustion process of the dehydrated cake. It is required to minimize the pollutants contained in it.
For this reason, when supplying a dewatered cake with a water content of about 75-80% in a sludge storage tank to an incinerator with a dewatered cake pump, the dehydrated cake pump is driven and adjusted to control the amount of dehydrated cake supplied. Yes.
[0003]
[Problems to be solved by the invention]
When a substance with gas generation such as sludge stays in a sealed state such as a pipe, the pressure increases in the pipe due to the generated gas. When the generated gas in the pipe is put into the incinerator without degassing, the cake is excessively supplied and burned in the furnace, causing a rapid rise in the furnace pressure. The gas in the furnace is released into the atmosphere, which is a safety and environmental problem. For this reason, a feeding device with a buffer equipped with an indenter or a cutting conveyor is provided in the cake charging part to prevent an increase in pressure in the piping, but it is difficult to maintain stable combustion due to variations in cake charging. There is.
[0004]
Therefore, the present invention provides a method for solving a problem at the start of charging in a sludge incinerator by direct charging of cake that has high quantitativeness and enables stable combustion control without providing a buffered supply device. The present invention provides a direct input device that degasses gas in a supply pipe generated by anaerobic fermentation.
In the cake direct charging method of the present invention, since degassing cannot be performed in the buffer tank, degassing in the supply pipe is performed by the following method. That is, it is difficult to separate the gas that has been anaerobically fermented in the dewatered cake transport pipe from the cake and degas only the gas. As a degassing method, the gas was fermented after closing the charging from the charging nozzle. The cake in the storage tank that is the supply source of the dehydrated cake is supplied into the pipe to replace the dehydrated cake that has not undergone fermentation. The cake that has been anaerobically fermented is returned to the storage tank that is the supply source, degassed by opening and stirring, and can be supplied again, and then put into an incinerator and incinerated.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, claim 1 of the present invention provides a dewatering cake pump disposed below the sludge storage tank, and the dewatering cake pump and the incinerator are connected by a supply pipe to dehydrate the sludge storage tank. In the dewatering cake charging device for charging cake into the incinerator, each of the two supply pipes each equipped with a dewatering cake pump is equipped with a three-way valve as a device valve and a pressure gauge, and a nozzle for dewatering cake charging Installed into two supply lines, connected to the return pipe from the upstream side of the three-way valve in each supply line toward the sludge storage tank, and put the dewatered cake out of the downstream side of the three-way valve in each supply line It not on the side connected to the use nozzle, the communicating pipe for communicating the other side with each other is provided, during the population dehydrated cake by the first or second supply line, the La by anaerobic fermentation of dewatered cake When the supply pipe pressure emissions exceeds the predetermined value, the by flowing dehydrated cake into the communicating pipe by switching three-way valve, a supply line to one system, supplying the dehydrated cake of the tube of the second or first having a control unit for controlling to open degassed returned to the sludge storage tank from the return tube connected to the line, characterized in that.
[0006]
With this configuration, when the pressure in the pipe rises due to anaerobic fermentation of the dehydrated cake in the supply pipe and exceeds a predetermined value, the three-way valve is driven by the control unit, and the dehydrated cake is sludge through the return pipe. Returned to storage tank.
[0007]
According to a second aspect of the present invention, a dewatering cake pump is disposed below the sludge storage tank, and the dewatering cake pump and the incinerator are connected by a supply pipe so that the dewatered cake from the sludge storage tank is placed in the incinerator. In the dewatered cake charging device to be charged into the tank, first and second dewatered cake pumps are provided below the sludge storage tank, and the first and second dewatered cake pumps and the incinerator constitute two supply lines. first, respectively connected with the second supply pipe, the first, the second supply pipe, first, second three-way valve and the first, the second pressure gauge first, second three-way a device valve first and second and cake injection nozzle provided with respective downstream of the valve, the first, towards the sludge storage tank downstream side of the second three-way valve to derive the return pipe respectively, and the respective supply line Connected to the dewatering cake charging nozzle on the downstream side of the three-way valve That is not a side, a communication pipe for communicating the other side with each other is provided, further, when the dehydrated cake is supplied to the incinerator using the first or the second supply pipe, the supply pipe by anaerobic fermentation of dewatered cake When the pressure rises and exceeds a predetermined value , switch the delivery path of the three-way valve in the supply pipe and the three-way valve in the other supply pipe to the other side, not the side connected to the nozzle for charging the dehydrated cake. After the supply line is made into one system and the dewatered cake in the pipe is circulated from the return pipe to the sludge storage tank to deaerate the supply pipe, the delivery path of the three-way valve in the supply pipe is connected to the first or second supply line. the dehydrated cake which is not fermented by switching to injection nozzle side provided with a control unit for controlling to supply the incinerator, characterized in that.
[0008]
By configuring in this way, when the pressure in the supply pipe rises and exceeds a predetermined value, the three-way valve and the return valve are driven by the control unit, and the dewatering cake connects the pipe from the three-way valve of the supply pipe. To the other three-way valve and then returned to the sludge storage tank through the other supply pipe and return pipe. In addition, since two dewatering cake supply systems are provided, the other supply pipe is used when returning the dehydrated cake, so that the return pipe can be reduced.
[0009]
In the present invention, the first and second branch supply pipes are connected to the first and second supply pipes, and a three-way valve, a pressure gauge, and a dewatered cake are added to each of the supply pipes and the branch supply pipes. In addition, each branch supply pipe is disposed around the incinerator at a position higher than the return pipe opening to the sludge storage tank. With this configuration, when the dewatering cake pump is stopped, the increased pressure around the branching portion to the charging nozzle is naturally released by gravity, and the replacement operation time (number of times) can be reduced.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a piping diagram of a dewatered cake direct charging apparatus according to the present invention, and shows a state of charging using a first supply line as will be described later.
In FIG. 1, reference numeral 1 denotes a sludge storage tank. In this storage tank, a dewatered cake obtained by dewatering suspended solids originally contained in sewage and manure and surplus sludge solids from sewage treatment (manure treatment). Is stored. The dewatered cake in the sludge storage tank 1 is pumped to the supply pipe, and directly fed into the incinerator 2 through the nozzle at the tip, and incinerated.
[0011]
The incinerator 2 incinerates the dehydrated cake using, for example, a fluidized bed, and the incineration ash is discharged from the incinerator 2 together with the combustion exhaust gas and cooled to a predetermined temperature by a heat exchanger or the like, and then a cyclone, The dust is removed by an electric dust collector or the like, and the exhaust gas is released from the chimney to the atmosphere.
[0012]
In the lower part of the sludge storage tank 1, for example, first and second dewatering cake pumps 3 and 4 that can adjust the transport amount (supply amount) by controlling the number of rotations of the motor are arranged, and on the discharge side thereof Supply pipes 5 and 6 constituting the first and second supply lines are connected to each other. The first and second supply pipes 5 and 6 include first and second discharge valves 7 and 8, supply valves 19 and 20, flow meters 17 and 18, moisture content meters 27 and 28, and a three-way valve 11 that is a device valve. , 21 are interposed. The branch supply pipes 5a and 6a are branched from the downstream side of the supply valves 19 and 20, and the three-way valves 12 and 22 as device valves are provided.
In the switching path of the three-way valves 11 and 12 arranged in the first supply line (the first supply pipe 5 and the branch supply pipe 5 a ) , flow rate adjusting valves 13a and 13b, pressure gauges 14a and 14b, and a device auxiliary valve (input) shut-off valve) 15a, injection nozzle 16a through 15b, 16b are connected respectively, the second supply line (second supply pipe 6, switching of the branch supply pipe 6 a) in the arranged three-way valves 21, 22換路Are connected to injection nozzles 26a and 26b through flow rate adjusting valves 23a and 23b, pressure gauges 24a and 24b, and device auxiliary valves (input cutoff valves) 25a and 25b, respectively. In addition, return pipes 35 and 36 with return valves 37 and 38 are provided in order to circulate the dehydrated cake from the first and second supply pipes 5 and 6 downstream of the flow meters 17 and 18 to the storage tank 1.
The said branch supply pipes 5a and 6a are arrange | positioned around an incinerator in the position higher than the return pipe open part to the sludge storage tank 1. FIG. In this way, when the dewatering cake pumps 3 and 4 are stopped, the increased pressure around the branching portion to the charging nozzle is naturally released by gravity, and the operation time (number of times) for replacement can be reduced.
The supply valves 19 and 20 are opened and closed during the maintenance of the pipeline. The three-way valve may be any valve that can switch the valve. For example, an electric three-way valve, a pneumatic three-way valve, or the like is used, and a motor drive, an air drive, or the like is used for driving the valve.
[0013]
Furthermore, the delivery sides of the three-way valves 11 and 21 and the delivery sides of the three-way valves 12 and 22 at the downstream positions of the supply pipes 5 and 6 are connected to each other by pipes 30a and 30b, respectively. When the pressure in the supply pipe exceeds a predetermined value due to the fermentation, the three-way valve is switched to make the supply line one system, and the dewatered cake in the pipe is returned to the sludge storage tank 1 from the return pipe and opened and deaerated. Supplying the dehydrated cake supplied to the incinerator 2 by controlling the motor of the first or second dehydrated cake pump 3 or 4 by the control unit 40 according to the measured values of the first and second flow meters 7 and 8 at the time of charging. The amount is adjusted. In order to reduce the output of the dewatering cake pumps 3, 4, the dewatered cake is preferably transported through the supply pipes 5, 6 at a flow rate of 2 to 4 cm / s or less, for example.
[0014]
In addition, the control unit 40 performs arithmetic processing based on measurement signals from a flow meter, a concentration meter, and a pressure gauge provided in each of the two supply lines and a predetermined program, and performs first and second dewatering cake pumps. Operation signals are output to the discharge valve, the three-way valve, the device valve subvalve, etc., and the charging / circulation operation is performed in a balanced manner. It is preferable to have a function of supplying the dehydrated cake to the incinerator 2 after returning the dehydrated cake in the supply pipes 5 and 6 to the sludge storage tank 1 at the start of operation. Note that if the dehydrated cake stays in the supply pipe that stops the supply of the dehydrated cake to the incinerator 2 among the two systems, the gas is fermented to generate gas, so that the gas is in the supply pipe 5 or 6. It is preferable to drive the dewatering cake pump 3 or 4 so that the dewatering cake in the supply pipe is returned to the sludge storage tank 1 periodically or irregularly so as not to stay.
[0015]
Usually, the dewatered cake is charged using a plurality of charging nozzles. In the illustrated example, two injection nozzles 16a, 16b, 26a, and 26b are used at the same level in the freeboard of the incinerator, for a total of four injection nozzles 16a, 16b, 26a, and 26b. The charging nozzle may be configured in any way as long as the dewatered cake can be charged (supplied) into the incinerator. For example, the charging nozzle may be charged using high-pressure air. The branch positions of the first and second supply pipes 5 and 6 are not particularly limited, but are preferably in the vicinity of the incinerator in order to reduce the supply pipes as much as possible.
[0016]
The control unit 40 drives either one of the dewatering cake pumps, for example, the first dewatering cake pump 3, and feeds a part of the dewatering cake of the sludge storage tank 1 from the charging nozzles 16 a and 26 a via the first supply pipe 5. When the measured values of the pressure gauges 14a and 14b of the first supply pipe 5 and the first branch supply pipe 5a exceed a predetermined value before being operated (supplied) into the incinerator 2, the first return pipe The first three-way valves 11 and 12 are switched so that the dewatered cake is returned to the sludge storage tank 1 via 36.
[0017]
Next, the operation will be described. FIG. 1 shows the state of charging using the first supply line. In the figure, the solid line portion of the supply line indicates that the inside of the pipe is open and the dotted line portion is closed.
[0018]
At the start of the charging operation, the three-way valves (device valves) 11 and 12 in the first supply pipe 5 are switched as shown in FIG. 1 to communicate with the charging nozzles 16a and 16b. Drive. The dewatered cake in the sludge storage tank 1 is sequentially supplied into the supply pipe 5 by the dewatered cake pump 3, and is introduced into the incinerator 2 from the nozzles 16a and 16b through the device valve sub valves 15a and 15b, and incinerated at a temperature of about 800 ° C. The
[0019]
FIG. 2 is a diagram showing a case where the dewatered cake is circulated from the piping to the sludge storage tank. Before the operation according to FIG. 1, when the dehydrated cake is fermented in the supply pipe 5 conveyed to the incinerator 2 to generate gas and the pressure in the pipe rises and exceeds a predetermined value, the control unit 40 Each of the three-way valves 11, 12, 21, 22 is driven to connect the pipes 30 a, 30 b and switch as shown by the solid line in FIG. 2, and the dewatered cake is returned to the sludge storage tank 1 through the return pipe 36. In addition, illustration of the said control part 40 is abbreviate | omitted in FIG.
It is difficult to separate the gas that has been anaerobically fermented in the dehydrated cake transport pipe from the cake and degas only the gas. As the deaeration method, after closing the charging from the charging nozzle, the cake in the storage tank, which is the supply source of the fermented dehydrated cake, is supplied into the pipe to replace the dehydrated cake in which fermentation has not progressed. The cake that has been anaerobically fermented is returned to the storage tank that is the supply source, opened and degassed, and can be supplied again. The cake is put into an incinerator and incinerated.
[0020]
When the inside of the supply pipe reaches a positive pressure, an excessive supply of the extruded cake is caused. As described above, the generated gas is returned to the sludge storage tank 1 together with the dehydrated cake and is released there, so that the generated gas incinerator 2 By suppressing the supply to the furnace, it is possible to prevent a combustion failure due to a rapid rise in the furnace pressure.
[0021]
When the cake charging operation is performed from the second supply line 6, the discharge valve, the device valve, and the like are switched to drive the second dewatering cake pump to send the dewatering cake to the second supply pipe 6 and the second charging nozzle 26a. 26b, and when the internal pressure of the pipe rises, the three-way valve is switched to form a degassing circulation circuit, but the illustration of the piping during the operation circulation of the second supply line is omitted.
[0022]
FIG. 3 is a diagram showing the open / closed state of each discharge valve, device valve, device valve subvalve, and return valve when dewatered cake is charged and circulated using the first and second lines.
When supplying dehydrated cake, when the gas is generated in the supply pipes 5 and 6 and the pressure exceeds a predetermined value, the control unit 40 switches the three-way valves 11 and 12 of the supply pipes 5 and 6. After deaeration, the dewatering cake pump of the other system and the three-way valves 21 and 22 are controlled so that the dewatering cake is supplied from a separate supply pipe to the incinerator 2 through the charging nozzle, thereby incinerator It is possible to prevent an excessive supply of the dehydrated cake due to the inflow of gas.
[0023]
【The invention's effect】
As described above, according to the first aspect of the present invention, when the dewatered sludge cake is introduced into the incinerator, the sludge cake is anaerobically fermented in the first or second supply pipe, and the pressure in the supply pipe increases. However, when the predetermined value is exceeded, the dewatering cake is returned to the sludge storage tank via the return pipe by driving the three-way valve and the return valve by the control unit and switching the two supply lines to one system. Supply of gas generated in the supply pipe to the incinerator is suppressed.
[0024]
According to the second aspect of the present invention, since the three-way valve is provided in the vicinity of the incinerator of the supply pipe, almost all of the dehydrated cake in the supply pipe can be returned to the incinerator. Does not stay, and the inflow of the pressurized gas to the incinerator can be reliably suppressed. Further, according to the invention described in claim 3, since each branch supply pipe is arranged around the incinerator at a position higher than the return pipe opening portion to the sludge storage tank, when the dewatering cake pump is stopped. The operating time (number of times) of replacing the increased pressure around the branching portion to the charging nozzle by naturally releasing by gravity can be reduced. Further, inflow of gas to the incinerator can be suppressed, and the other supply pipe is used when returning the dehydrated cake, so that the return pipe can be reduced.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing a state in which dehydrated cake is charged into an incinerator from a first supply line of the dehydrated cake charging device of the present invention.
FIG. 2 is a diagram showing a case where a dehydrated cake whose pressure has been increased in the pipe of FIG. 1 is circulated in a sludge storage tank and a dehydrated cake and a replacement without pressure increase are supplied.
FIG. 3 is a view showing an open / closed state of each discharge valve, device valve, device valve subvalve, and return valve when charging and circulating dehydrated cake.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Sludge storage tank 2 Incinerator 3 1st dehydration cake pump 4 2nd dehydration cake pump 5 1st supply pipe 6 2nd supply pipe 5a, 6a Branch supply pipe 7, 8 Discharge valve 9, 10 Discharge pressure gauge 11, 12 1st 1 device valve (3-way valve) 21, 22 2nd device valve (3-way valve)
13a, 13b, 23a, 23b Flow rate adjusting valves 14a, 14b, 24a, 24b Input pressure gauges 15a, 15b, 25a, 25b Device valve sub-valve (input cutoff valve)
16a, 16b 1st injection nozzle 26a, 26b 2nd injection nozzle 17, 18 Flow meter 19, 20 Supply valve 27, 28 Moisture content meter 35, 36 Return pipe 37, 38 Return valve 40 Control device

Claims (3)

In the dewatering cake charging device that places the dewatering cake pump below the sludge storage tank, connects the dewatering cake pump and the incinerator with a supply pipe, and inputs the dehydrated cake from the sludge storage tank into the incinerator.
Each of two supply pipes each equipped with a dewatering cake pump is equipped with a three-way valve, which is a device valve, and a pressure gauge, and a dehydrating cake charging nozzle is attached to each of the two supply lines,
The return pipe is connected to the sludge storage tank from the upstream side of the three-way valve in each supply line, and the downstream side of the three-way valve in each supply line is not the side connected to the dewatered cake charging nozzle, Provide a communication pipe that communicates the other side,
When turning on the dewatered cake by the first or second supply line, when the supply pipe pressure of the line exceeds the predetermined value by anaerobic fermentation of dehydrated cake, the dehydrated cake in the communicating pipe by switching the three-way valve By supplying the flow line , the supply line is made into one system, and the dewatering cake in the pipe is returned to the sludge storage tank from the return pipe connected to the second or first supply line, and is equipped with a control unit that controls to open and deaerate.
A dehydrating cake direct charging device. In the dewatering cake charging device that places the dewatering cake pump below the sludge storage tank, connects the dewatering cake pump and the incinerator with a supply pipe, and inputs the dehydrated cake from the sludge storage tank into the incinerator.
First and second dewatering cake pumps are provided below the sludge storage tank, and these first and second dewatering cake pumps and the incinerator are first and second supply pipes constituting two supply lines. Connect each one
The first and second supply pipes are provided with first and second three-way valves and first and second pressure gauges, which are device valves, and first and second cake injection nozzles downstream of the first and second three-way valves. And a return pipe is led out toward the sludge storage tank from the downstream side of the first and second three-way valves, and the dewatering cake is charged in the downstream side of the three-way valve in each supply line. Provide a communication pipe that connects the other side, not the side connected to the nozzle,
Further, when the dehydrated cake is supplied to the incinerator using the first or second supply pipe, when the pressure in the supply pipe rises and exceeds a predetermined value due to anaerobic fermentation of the dehydrated cake, three directions in the supply pipe Switch the delivery path of the three-way valve in the valve and the other supply pipe to the other side, not the side that connects to the nozzle for charging the dehydrated cake, to make the supply line one system, and the dewatered cake in the pipe to the sludge storage tank from the return pipe After degassing the supply pipe,
A control unit is provided for controlling the delivery path of the three-way valve in the supply pipe to the input nozzle side of the first or second supply line to control the supply of the unfermented dehydrated cake to the incinerator. Dehydrating cake charging device. First and second branch supply pipes are connected to the first and second supply pipes, and a three-way valve, a pressure gauge, and a dewatering cake charging nozzle are attached to the supply pipes and the branch supply pipes, respectively. And the said each branch supply pipe | tube is arrange | positioned around an incinerator in the position higher than the return pipe open part to a sludge storage tank, The dewatering cake injection | throwing-in apparatus of Claim 2 characterized by the above-mentioned.

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