JPS581969B2 - pyrolysis equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a two-column circulation type thermal cracker in which a fluidized medium circulates between two columns, a cracking column and a combustion column.

The decomposition tower for combustible gas and the combustion tower for air are connected by two connecting pipes, and when these connecting pipes are filled with fluid and move, the two towers are separated. We are doing a seal between the two.

However, if the pressure balance between the two towers becomes different, or if the fluidized sand decreases or shifts to one side, the amount of fluidized medium in the connecting pipe will decrease, and it will eventually blow through, making it impossible to continue operation and creating a dangerous situation. Met.

The inventors conducted experiments and research to prevent problems caused by this blow-through, and found that in order to operate stably and safely, it was necessary to maintain the top pressure and differential pressure between the tops of the cracking tower and the combustion tower. It was found that it is important to maintain the amount of gas flowing into the cracking tower and combustion tower, and to maintain the amount of fluidized sand packed.

The present invention was made based on the knowledge obtained through this experiment and research, and it is possible to effectively and reliably perform control for stable operation in a two-column circulation type thermal cracker and emergency shutdown in an emergency situation. It is an object of the present invention to provide a pyrolysis apparatus that can prevent leakage and explosion risks due to increases in absolute pressure.

The present invention includes a fluidized bed pyrolysis tower and a fluidized bed sintering tower, the combustion tower is formed by connecting an upper combustion chamber and a lower pumping section with a pumping pipe, and the combustion tower It has an upper connecting pipe that descends from the cracking tower to the cracking tower, and a lower connecting pipe that descends from the cracking tower to the pumping section, and circulates a fluidized medium between the thermal cracking tower and the combustion tower to generate heat. In a two-column circulation type pyrolysis apparatus that performs decomposition: detecting the top pressure of the decomposition column, and adjusting the opening degree of a first control valve provided in the pyrolysis product gas flow path according to the signal; A pressure difference between the tops of the cracking tower and the combustion tower is detected, and according to the signal, the gas is provided in a flow path for the pyrolysis product gas to be returned to the cracking tower for fluidization in the cracking tower. This pyrolysis apparatus is characterized in that at least one of the second control valve and the third control valve provided in the flue gas flow path of the combustion chamber is adjusted.

To explain the present invention with reference to the drawings, the main equipment of the pyrolysis apparatus is a cracking tower 1 and a combustion tower 2.
A fluidized medium pumping section 3 and a pumping pipe 4 are provided at the bottom, and a combustion chamber 5 is provided at the top.

An upper connecting pipe 6 and a lower connecting pipe 7 are provided between the combustion chamber 5 and the cracking tower 1, and between the cracking tower 1 and the pumping section 3, respectively.

The cracking column 1 has a porous bed plate 9 to form a fluidized bed 8 therein;
It is equipped with a circulating gas chamber 10, a circulating gas inlet 11, a raw material inlet 12 such as garbage, and a produced gas outlet 13.

The pumping section 3 includes a nozzle pipe 16 having a nozzle 14 that generates an upward jet stream, a stirring nozzle 15 that stirs the surrounding area, a nozzle air blowing port 17, and a suction port 1 at the lower end of the pumping pipe 4.
8 is provided.

The combustion chamber 5 is provided with an upper end 19 of a lift pipe 4 protruding from the floor surface, and is provided with a gas outlet 20 and an auxiliary burner 21.

22 and 23 are a fuel valve and an air valve for the auxiliary burner 21, respectively.

The generated gas path includes a cyclone 24, a fuel exchanger 25, a cooling tower 26, a valve 27 (as a first control valve provided in the pyrolysis generated gas flow path), a branch point 28, a blower 29, and connects these. It is composed of a generated gas pipe 30.

31 is a solid matter discharge pipe. Part of the generated gas is transferred to decomposition tower 1
The circulating gas path that is circulated as a fluidizing gas includes a branch point 28, a blower 32, and a valve 33 (a second control valve provided in the flow path of the pyrolysis product gas that is returned to the cracking tower for fluidization). ), heat exchanger 25, valve 34, air inlet 11
and a circulating gas pipe 35 connecting these.

51 is a foreign matter removal tube. 36 is an air pipe that sends air from an air source such as a blower to the inlet 17, and 37 and 38 are valves.

To explain the control relationship, 39 is the tower top 4 of the cracking tower 1.
0 pressure and the pressure at the top 41 of the combustion tower 2 △po
42 is the decomposition column 1
43 is a pressure difference detector that detects the pressure difference Δp1 at measurement points 44 and 45 of the upper connecting pipe 6 and issues a signal, 46 is a lower connecting tube 6. Difference in pressure Δp at measurement points 47 and 48 of tube 7
This is a pressure difference detector that detects 2 and issues a signal.

49 is a control mechanism that controls the valve 27 in response to a signal from the pressure detector 42, and operates to open the valve 27 when the tower top pressure becomes high;
2 (as a third flow rate control valve provided in the flue gas flow path), and when the pressure difference exceeds the limit while the top pressure of the combustion tower 5 is higher, the valve 52 It operates to open.

・50 receives signals from the pressure difference detectors 42, 39, 43, 46, and when any of p, △Pot△pat△p2 reaches the stability limit, part or all of the valves 33, 37, 22, 23 are activated. It also has a function to ensure safety by shutting off.

To explain the operation of the above embodiment, raw materials such as municipal waste inputted from the raw material inlet 12 are heated and thermally decomposed in the fluidized bed 8, and the generated gas is passed through the generated gas pipe 30 and transferred to the next process by the reblower 29. A part of the produced gas is separated at a branch point 28 and is passed through a blower 32 through a circulating gas pipe 35 into the circulating gas chamber 10 through the inlet 11 and blown upward from the porous floor plate 9 to form a fluidized bed 8.

The fluidized medium in the fluidized bed 8 passes through the lower connecting pipe 7 and enters the pumping section 3 .

A nearby fluid medium is stirred and floated by a stirring nozzle 15 provided in the lifting section 3, and a jet stream ejected vertically upward from the nozzle 14 causes the fluid medium to flow into the lifting pipe 4.
It rises inside and flows into the combustion chamber 5 from the upper end 19, and the burner 21
The fluidized medium is heated and combustible materials such as char and other organic substances are burned and regenerated;
It passes through and enters the decomposition tower 1 again.

The stability of the two-column circulation pyrolysis device is determined by the cracking column 1 and combustion column 2.
It depends on the sealing performance of the upper and lower connecting pipes 6 and 7 by the fluid medium.

According to experiments and research conducted by the inventors, when the seal caused by the fluidized medium begins to collapse, that is, when the upper and lower connecting pipes 6 and 7 begin to blow through, bubbles are generated in the fluidized medium layer in the connecting pipes, and this phenomenon occurs in the connecting pipes. It was found that changes can be clearly confirmed by measuring the differential pressure between the top and bottom of the

In other words, when bubbles start to occur, the pressure difference between the top and bottom of the connecting pipe suddenly increases and shows a peak, or changes significantly but not as sharply as the peak, so the pressure difference is within the stable limit. If so, the control mechanism 49,
53 to control the valve 27 or 52 to eliminate the abnormal condition, and when the differential pressure exceeds the stability limit, the valve 33 is immediately adjusted.
, 37, 22, and 23 so that emergency stabilization and safety measures can be taken.

Further, a continuous stability limit is set for a differential pressure lower than the above-mentioned stability limit, and even if this value is exceeded for a certain period of time or more, the control mechanism 50 is activated to open the valve 33. 37, 22. 23 may be cut off in an emergency.

Although it is best to set these two emergency cutoff conditions in parallel, either one of the conditions may be set.

When a measurement hole is provided in the upper and lower connecting pipes 6 and 7 for detecting a pressure difference, the measurement hole is likely to become clogged with a fluid medium and cause an error.

As a result of research conducted by the inventors, it has been confirmed that the occurrence of bubbles in the upper and lower connecting pipes 6 and 7 can be detected by calibrating the measured value based on the differential pressure between the tops of both columns.

Therefore, if both the detection of the pressure difference between the upper and lower connecting pipes 6 and 7 and the detection of the pressure difference between the tower tops are used together, it becomes reliable.

It is also possible to detect only the differential pressure between the tower tops.

It is conceivable to provide a valve in each of the upper and lower connecting pipes 6 and 7 and to adjust the valve based on the pressure difference at the top of the tower, but this is not desirable because it causes severe wear on the valve.

Furthermore, even if the pressure difference between the two columns is within the allowable value, if the absolute pressure becomes large, there is a risk of leakage and explosion, so in order to prevent this, the top pressure of the cracking column 1 is detected and the allowable limit is set. If it exceeds the high pressure gas, the valve 27 or the valve on the suction side of the blower 29 (both correspond to the first control valve provided in the pyrolysis product gas flow path) is controlled to release the high pressure gas, or the valve 33 is controlled. It is possible to reduce the fluidizing gas, weaken the thermal decomposition effect, lower the absolute pressure inside the cracking tower 1, and ensure safety.

The present invention prevents measurement errors due to blockage of the fluid medium or instability of the internal pressure of the detection part, prevents blow-through in the connecting pipe with high reliability, ensures safe and stable operation, and reduces internal pressure. It is possible to provide a pyrolysis equipment that can prevent risks such as leakage and explosion due to ascent, and perform emergency shutdown in an emergency situation to ensure the stability and safety of the equipment. Above all, it has an extremely large effect.

[Brief explanation of the drawing]

The drawing is a flow sheet of an embodiment of the present invention. 1... Decomposition tower, 2... Combustion tower, 3...
... Lifting section, 4... Lifting pipe, 5...
- Combustion chamber, 6... Upper connecting pipe, 7... Lower communicating pipe, 8... Fluidized bed, 9... Porous floor plate, 10... ... Circulating gas chamber, 11... Inlet, 12... Raw material inlet, 13...
Generated gas outlet, 14... Nozzle, 15...
... Stirring nozzle, 16... Nozzle pipe, 17...
...Inlet, 18...Suction port, 19...
...Top end, 20...Gas outlet, 21...
...Burner, 22...-Fuel valve, 23...
・Air valve, 24...Cyclone, 25i...
...Heat exchanger, 26...Cooling tower, 27...
...Valve, 28... Branch point, 29...
Blower, 30...Produced gas pipe, 31...
・Solid discharge pipe, 32...Blower, 33, 34
... Valve, 35 ... Circulating gas pipe, 36.
...Air pipe, 37,38...Valve, 39.
... pressure detector, ) 40, 41 ... tower top, 42 ... pressure detector, 43 ... pressure difference detector, 44, 45 ... ...Measurement point, 46...
...Pressure difference detector, 47, 48...Measurement point, 49,50...Control mechanism, 51...
Foreign matter removal tube.

Claims (1)

[Claims] 1. A fluidized bed pyrolysis tower and a fluidized bed combustion tower, the combustion tower is formed by connecting an upper combustion chamber and a lower pumping section with a pumping pipe, It has an upper connecting pipe that descends from the combustion chamber to the cracking tower, and a lower connecting pipe that descends from the cracking tower to the pumping section, and circulates a fluidized medium between the thermal cracking tower and the combustion tower. In a two-column circulation type pyrolysis device that performs pyrolysis using a pyrolysis device; the above-mentioned decomposition column pressure is detected, and the opening degree of a first control valve provided in a pyrolysis product gas flow path is adjusted according to the signal. detecting the differential pressure between the tops of the cracking tower and the combustion tower, and depending on the signal, controlling the flow path of the pyrolysis product gas to be returned to the cracking tower for fluidization in the cracking tower; A pyrolysis apparatus characterized in that at least one of a second control valve provided in the combustion chamber and a third control valve provided in a combustion exhaust gas flow path of a combustion chamber is adjusted.