JPS5944348B2 - Fluidized medium pumping device for multi-column circulation pyrolysis equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a multi-column circulation type pyrolysis device that pyrolyzes organic materials such as municipal waste by circulating a fluidized medium using a pyrolysis tower, a combustion tower, and a fluidized medium pumping mechanism. The present invention relates to a fluid medium pumping device that prevents clogging of a pumping path.

In a multi-column circulation type pyrolysis equipment, the temperature of the fluidized medium in the pyrolysis tower drops due to the thermal decomposition of the raw material, so in order to compensate for the amount of heat, the fluidized medium is circulated between the pyrolysis tower and the combustion tower, and the combustion It is reheated in the tower and supplied to the pyrolysis tower again.

The pyrolysis tower in a combustible gas atmosphere and the combustion tower in an air atmosphere are connected by two connecting pipes, and the heat medium forms a moving layer in these connecting pipes, creating a gas seal between the two units. I am doing it.

For example, as shown in FIG. 1, a fluidized bed is formed in the pyrolysis tower 1 by recirculating pyrolysis gas or steam, and the combustion tower 2
In this case, air or steam containing air is blown from a nozzle 9 in an ejector part 8 serving as a pumping mechanism, and the fluidized medium is pumped through a pumping pipe 7 to form a fluidized bed in the upper part of the combustion tower 2.

The two units are connected by communication pipes 10 and 11 filled with a fluidizing medium to seal each gas and form a moving bed in the direction of the arrow.

The amount of fluidized medium circulated is controlled by varying the amount of ring gas.

In such a two-unit circulation type pyrolysis apparatus, maintaining a seal between the two units and controlling the circulation amount of the fluidizing medium to an appropriate value are important operational factors.

The problem with sealing between the two units is the lower connecting pipe 1.
1, when gas leaks from the combustion tower 2 to the pyrolysis tower 1, if the amount is small compared to the amount of fluidized gas in the pyrolysis tower 1, there will be no problem in reducing the calories of the generated gas, but if there is a large amount This not only causes a decrease in the calorie content of the generated gas (it also impedes the circulation of the fluid medium).

The cause of the gas leak is the pressure increase in the ejector part 8.
This is often caused by an increase in differential pressure in the pumping section.

In a two-unit circulation type pyrolysis apparatus, the temperature difference of the fluidized medium between the two units is determined by the throughput of the raw material and the amount of circulation of the fluidized medium. The reheating temperature of the medium is desirably low, and conversely, the thermal decomposition temperature in the thermal decomposition column is desirably high in order to increase the gasification rate.

Therefore, in order to keep the temperature difference between the two units small, the circulation rate of the fluid medium must be maintained at a certain level.

However, if the mixing ratio between the pumping gas and the fluidizing medium is high, the differential pressure inside the pumping pipe 7 will rise, and the pressure in the ejector part 8 will rise, causing gas leakage from the lower connecting pipe 11 toward the pyrolysis tower 1. It has been found through experiments conducted by the inventors that this occurs.

If the amount of pumping gas is increased sufficiently, the mixing ratio will be reduced and this problem will be solved, but this will not only increase the size of the pumping gas supply equipment, but also increase the amount of exhaust gas from the combustion tower, and the exhaust gas treatment equipment will also become larger. This becomes extremely uneconomical.

Furthermore, as the speed in the pumping pipe increases, the amount of friction of the heat medium increases rapidly, causing an increase in operating costs.

Although the theoretical amount of air required for combustion of char, tar, etc. is the minimum required, for the above-mentioned reasons, it is necessary to circulate a large amount of heat medium with a small amount of pumping gas.

For this reason, when the fluidizing medium near the nozzle 9 is fluidized by the fluidizing ring 4 as shown in Fig. 2, the fluidizing medium is uniformly mixed with the pumping gas from the nozzle 9, and a small amount of pumping gas is used to increase the flow rate. Stable operation can be performed at a certain mixing ratio.

a is a ring gas, b is a pumping gas, and C is a mixture of gas and fluidizing medium.

FIG. 3 shows the relationship between the amount of gas for the fluidizing ring and the amount of fluidized medium pumped (circulated amount).

The limit line LO8 side indicates a stable circulation region, and the U side indicates an unstable circulation region.

The amount of gas for pumping is large in the M direction and small in the N direction.

A and B indicate operating points that give the same fluidized medium circulation amount, but although B is more stable than A, A is preferable to B in that A requires less pumped gas.

However, when municipal waste is thermally decomposed, incombustible materials such as metals, glass, earth and debris, and coarse fluidized media (collectively referred to as foreign matter) remain in the fluidized bed, resulting in a large amount of waste. Portions are continuously ejected.

In order to eliminate these foreign substances, a gas such as steam is blown into the bottom of the fluidized bed of the pyrolysis tower 1 as a foreign substance classification gas, as shown in FIG. The foreign matter is allowed to fall downward through a pipe 28, and a double valve system is used to discharge foreign matter without releasing the gas inside the tower to any part.

The entrance of the lower connecting pipe 11 leading to the ejector part 8 of the combustion tower 2 is provided at a height that ensures the lowest bed height of the fluidized bed, so that almost no foreign matter enters the lower connecting pipe 11. However, a portion still moves along with the fluid medium through the lower connecting pipe 11 to the ejector part 8.

These foreign substances are lifted up along with the fluidized medium through the lifting pipe 7, but some of them accumulate around the nozzle 9 as shown by the foreign substance 5 in FIG. This may result in a sudden increase in the amount of fluidized medium being pumped.

Foreign matter in the ejector part 8 (similar to the fluidized bed in the upper part of the combustion tower 2) is discharged to the outside together with the fluidized medium through a pipe 29 provided at the lower part of the ejector part 8 by periodically opening and closing a valve. It is not continuous, and even if the accumulation is for a very short time, the operating point is near the unstable region, so slight disturbances tend to make the pumping condition unstable, and it is difficult to prevent the above phenomenon. .

This unstable state is caused by the differential pressure in the lift pipe 7 or the lower connecting pipe 11.
Conventionally, an upper limit value was set for the measured value of the differential pressure between the pumping section and the lower connecting pipe, and if the value exceeded this value, the operation could not be continued, and the equipment was stopped before a blockage or blow-through occurred. I had no choice but to stop driving, even if only temporarily.

The present invention eliminates the above-mentioned drawbacks of the conventional method by predicting blockage using a blockage prediction mechanism based on differential pressure detection in the pumping section, and blowing pressurized gas into the pumping path. It prevents blockage, reverse blow-through from the pumping mechanism to the pyrolysis tower, ensures stable circulation of the fluidized medium, and eliminates the need to stop pyrolysis operation midway.

The object of the present invention is to provide a fluidized medium pumping device for a multi-column circulation type pyrolysis device that is safe and highly reliable.

The present invention includes a pyrolysis tower, a combustion tower, and a fluidized medium transport mechanism, and connects these devices with a fluidized medium transfer path to circulate the fluidized medium to thermally decompose organic raw materials such as municipal waste. In the multi-column circulation type pyrolysis apparatus, a pressure gas blowing mechanism blows pressurized gas into a lift pipe which is a fluidized medium transfer path connecting the lift mechanism and the combustion tower, and It is equipped with a differential pressure detection mechanism that detects the differential pressure between the pressure of the column and the pressure of the pumping mechanism and the pressure of the pyrolysis, and the differential pressure detecting mechanism detects that the differential pressure is higher than a set value. A fluidized medium pumping device for a multi-column circulation type pyrolysis apparatus, characterized in that it is equipped with a control mechanism that issues a signal to operate the pressure gas blowing mechanism when a pressure rise is detected.

To explain the present invention with reference to the drawings, 1 is a pyrolysis tower, 2 is a combustion tower, 3 is an organic material feeder such as municipal waste, 4 is a fluidization ring, and 6 is a fluidization tower. Flow control valve for ring gas supplied to ring 4; 7 is a lift pipe; 8 is a part of the ejector; 9 is a nozzle; 10 and 11 are connecting pipes; 12 is a supply device for char or tar; 13 is a nozzle 9 is a flow control valve for the pumping gas supplied, 14, 15, 16, 17 are valves, 18 is a header for pressure gas, 19 is a pumping air supply device, 20 is an ejector part 8
21 and 22 are differential pressure detectors that detect the differential pressure between the two ends of the communication pipes 10 and 11, respectively, and 27 is for blowing in the gas for classifying foreign substances. A pipe, 28 is a pipe for dropping foreign matter, 29 is a pipe for discharging foreign matter accumulated in the ejector part 8, 30 is a foreign matter separation device, 31 is a combustion exhaust gas outlet, 32 is a fluidizing gas inlet, 33 is a generated gas outlet It is.

The sealing state between the two units is monitored by differential pressure detectors 21 and 22, and the differential pressure detector 20 measures the amount of circulation of the fluid medium or predicts blockage.

In such a two-unit circulation type pyrolysis apparatus, for some reason, the differential pressure in the pumping section detected by the differential pressure detector 20 may rise above the set value, and the pumping pipe 7 may be blocked by the fluidized medium. occurs, or when the differential pressure in the lower connecting pipe detected by the differential pressure detector 22 rises above the set value and there is a risk of gas leakage, and it is determined that this is caused by an increase in the differential pressure in the pumping section. When this occurs, either: ■ Operate the flow rate control valve 6 to reduce the flow rate of the ring gas for controlling the sand circulation amount to lower the pumping amount of the fluidized medium, or ■ Operate the flow rate control valve 13 to reduce the flow rate of the ring gas for controlling the sand circulation amount. Increase the flow rate of the pumping gas to lower the solid-air ratio in the pumping pipe.

However, when the lift pipe 7 is close to being blocked even after performing the steps ① and ②, several valves 14 to 17 installed vertically in the lift pipe 7 are opened. from 1
Occasionally blow in a pressurized gas such as a compressed pneumatic caster.

At this time, the valves may be opened in the order from above, or may be opened indiscriminately.

At the same time, a valve for discharging foreign matter provided in the ejector part 8 is opened to discharge foreign matter accumulated near the nozzle from the pipe 29, thereby eliminating the factor that made the pumping state unstable.

In this way, when the differential pressure in the pumping section gradually decreases and a stable pumping state is restored, the blowing of pressurized air into the pumping pipe 7 is stopped, and the respective flow rates of pumping gas and fluidizing ring gas are Return to the predetermined value.

In the combustion tower 2, as shown in FIG.
The fluidized medium that has been lifted up the lifting pipe 7 is discharged from the pipe 34 protruding into the fluidized bed and falls into the fluidized bed.

A pipe grid 23 is used as the fluidization device, and the generated char and tar supplied from the supply device 12 and the fuel gas supplied from the pipe grid 25 are combusted to raise and reheat the fluidized medium.

Note that the pipe 35 provided at the bottom of the fluidized bed is for discharging foreign matter.

Numerals 24 and 26 are fumarole holes for blowing out gas.

Although the above example shows a two-column type, the same applies to a multi-column type.

The present invention prevents blockage of the fluid medium in the pumping route or blow-through in the connecting pipe, ensures stable circulation of the fluid medium without interrupting equipment operation, and is safe and reliable. , it is possible to provide a fluidized medium pumping device for a multi-column circulation type pyrolysis device, and it has extremely practical effects.

[Brief explanation of the drawing]

Figure 1 is a flow diagram of the conventional system, Figure 2 is an explanatory diagram of the vicinity of the nozzle in the pumping section, Figure 3 is a diagram showing the relationship between the circulating medium flow rate and the ring gas volume, and Figure 4 is the main flow diagram. FIG. 5 is a flow diagram of an embodiment of the invention, and is an explanatory diagram of the vicinity of the combustion tower. 1...Pyrolysis tower, 2...Combustion tower, 3.
... Raw material supply device, 4 ... Fluidization ring, 5 ... Foreign matter, 6 ... Flow rate control valve, 7
... Lifting pipe, 8 ... Part of ejector, 9
... Nozzle, 10, 11 ... Communication pipe,
12... Supply device, 13... Flow control valve, 14, 15° 16.17... Valve, 18
...Pressed gas header, 19...Air supply device, 20, 21.22...Differential pressure detector, 23...Pipe grid, 24.・・・・・・
Fumarole, 25...Pipe grid, 26...
... fumarole, 27, 28, 29... pipe,
30... Foreign matter separation device, 31... Combustion exhaust gas outlet, 32... Fluidization gas inlet, 33.
...Produced gas outlet, 34°35...pipe.

Claims (1)

[Claims] 1 Multi-tower circulation system that is equipped with a pyrolysis tower, a combustion tower, and a fluidized medium pumping mechanism, and connects these devices with a fluidized medium transfer path to circulate the fluidized medium to thermally decompose organic raw materials such as municipal waste. In the type pyrolysis apparatus, a pressure gas blowing mechanism blows pressurized gas into a lift pipe which is a fluidized medium transfer path connecting the lift mechanism and the combustion tower, and the pressure of the lift mechanism and the pressure of the combustion tower. or a pressure difference between the pressure of the pumping mechanism and the pressure of the pyrolysis tower, and the pressure difference detection mechanism detects that the pressure difference has risen above a set value. 1. A fluidized medium pumping device for a multi-column circulation type pyrolysis apparatus, comprising a control mechanism that issues a signal to operate the pressure gas blowing mechanism when this is detected.