JPH0748576A - Dehydrochlorination vessel in waste-plastic liquefaction apparatus - Google Patents

Abstract

PURPOSE:To stabilize the air flow resistance of a dehydrochlorination vessel which removes chlorine contained in the vapor of an oil formed by thermal decomposition and thus prevents poisoning of a catalytic decomposition catalyst in a process for liquefying a chlorine-contg. waste plastic. CONSTITUTION:A waste-plastic liquefaction apparatus comprises a raw material mixing vessel for melting waste plastic, a thermal decomposition vessel for thermally decomposing the resultant melt, a dehydrochlorination vessel for removing chlorine produced in the decomposition vessel from the vapor of an oil formed by the thermal decomposition, and a catalytic decomposition vessel for reforming the vapor provided that an inorg. coarse particle layer having a thickness of 50-100mm and a particle size of 20-40mm is formed at least at the inlet side of the dehydrochlorination vessel and that a CaO layer having a particle size of 2-10mm is formed at the down-stream side of the coarse particle layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dehydrochlorination tank in oil treatment equipment for waste plastic materials.

[0002]

2. Description of the Related Art As a method for oil treatment of waste plastic materials, there is known a method of producing a low boiling point hydrocarbon oil by thermally decomposing a polyolefin waste plastic material as disclosed in Japanese Patent Laid-Open No. 3-86791. Has been.

FIG. 5 is a flow chart of the waste plastic material supplied in the equipment by this method. As shown in the figure,
The plastic material is first kneaded and melted by the extruder 1 and supplied to the raw material mixing tank 2. This molten plastic is completely melted by refluxing and mixing the pyrolysis oil produced in the thermal cracking tank 3 in the latter stage in the original mixing tank 2. Next, the completely melted plastic is sent to the thermal decomposition tank 3, and the heating furnace 4
It is heated and pyrolyzed by circulating between and. In the process of this thermal decomposition, a thermal decomposition oil vapor of plastic is generated from the thermal decomposition tank 3, and this thermal decomposition oil vapor is introduced into the catalytic decomposition tank 5 containing the synthetic zeolite catalyst, and by catalytic decomposition reaction with the catalyst. Decomposes and reforms into low boiling point hydrocarbon oil vapor. Next, this pyrolyzed oil vapor is condensed in a cooler 6 to obtain a low boiling point hydrocarbon oil.

However, in general waste plastic materials, 10 to 15 wt% of vinyl chloride is contained in addition to the polyolefin plastic, and hydrogen chloride is generated from this vinyl chloride during the thermal decomposition process. . Hydrogen chloride poisons the synthetic zeolite-based catalyst contained in the catalytic cracking tank and loses its catalytic effect. Further, if hydrogen chloride is mixed in the produced oil, there is a concern that harmful substances may be generated when the produced oil is burned, and thus it becomes unsuitable as a fuel oil, and the use of the produced oil is significantly narrowed.

Therefore, in order to obtain a good quality hydrocarbon oil by oil-treating a general waste plastic material by the method described in the above-mentioned Japanese Patent Laid-Open No. 3-86791, a thermal decomposition tank and a catalytic cracking tank are used. It is necessary to install a dehydrochlorination tank for removing hydrogen chloride between the two. In this dehydrochlorination tank, as a reaction agent for dehydrochlorination, Ca which is solid at a usual pyrolysis oil vapor temperature and easily reacts with hydrogen chloride.
Fill with O.

However, when the dehydrochlorination tank is filled with powdery or fine-grained CaO, when the pyrolysis oil vapor is passed through this packed bed, the mist-like pyrolysis oil entrained in the pyrolysis oil vapor is CaO. Adheres to and blocks the passage hole, which causes a rapid increase in pressure loss and
Unstable ventilation resistance occurs. Therefore, frequently unreacted Ca
The operation of the equipment becomes complicated, such as replacement of CaO with O remaining. In addition, due to local blockage, non-uniform flow of the pyrolyzed oil vapor occurs, which increases ventilation resistance and makes it impossible to obtain a sufficient dehydrochlorination effect. Therefore, problems such as acceleration of poisoning of the catalytic cracking catalyst and mixing of hydrogen chloride into the produced oil occur. Furthermore, since it is necessary to replace CaO frequently, running costs increase.

[0007]

The problem to be solved by the present invention is to remove dechlorination in a dehydrochlorination tank filled with CaO as a dehydrochlorination agent to be installed in an oilification facility by thermal decomposition of such waste plastic materials. It is to provide a means for stabilizing the hydrogen reaction for a long period of time.

[0008]

[Means for Solving the Subject] The dehydrochlorination tank in the oil treatment equipment for waste plastic materials according to the present invention comprises a raw material mixing tank for melting the waste plastic materials, followed by heat for thermally decomposing the melted plastic materials. Waste plastic material composed of a cracking tank, a dehydrochlorination tank for removing hydrogen chloride in the pyrolysis oil vapor generated in the pyrolysis tank, and a catalytic cracking tank for subsequently reforming the pyrolysis oil vapor The dehydrochlorination tank in the oilification treatment facility, wherein the layer thickness is 50 to 100 mm at least on the inlet side of the dehydrochlorination tank.
Inorganic coarse particles having a particle diameter of 20 to 40 mm are arranged, and the particle diameter is 2 to 10 on the downstream side of the inorganic coarse particle layer.
In the middle between the inlet and the outlet characterized by arranging CaO of mm, fine-grained CaO is filled.

As the inorganic coarse particles, chemical substances such as Al ₂ O ₃ , SiO ₂ and other ceramics, metals, glass, etc. which do not change or deform at a temperature of 420 ° C. or lower which is the maximum temperature of the pyrolysis oil vapor. It is possible to use those which do not have activity, and it is also possible to use coarse-grained CaO for dehydrochlorination by reacting the coarse grains themselves with hydrogen chloride.

[0010]

[Function] By disposing a coarse particle layer of an inorganic substance at least on the inlet side of the packed bed, mist-like pyrolyzed oil vapor is trapped in the coarse particle layer, so that clogging in the dehydrochlorination tank is prevented. However, the pressure loss in the tank can be kept low and stable. Further, since the pyrolyzed oil vapor is rectified by the coarse particle layer, the pyrolyzed oil vapor and the dehydrochlorination agent can be evenly contacted, and the dehydrochlorination efficiency can be improved.

Since the fine CaO layer provided in the middle has a large specific surface area of the granular body, the solid-gas contact efficiency can be enhanced. That is, the dehydrochlorination tank can be made smaller than when only coarse particles are filled, and the filled C
aO can be used efficiently.

Further, if a CaO layer of inorganic coarse particles is provided on the outlet side of the packed bed, it is possible to prevent the intermediate fine particles from scattering and mixing into the latter stage of the dehydrochlorination tank and preventing the catalyst tank from being blocked by the fine particles. it can.

[0013]

EXAMPLE FIG. 1 shows the structure of an oiling facility in which a dehydrochlorination tank according to the present invention is arranged. In the figure, the same parts as those of the conventional oiling equipment shown in FIG. 5 are denoted by the same symbols, 1 is an extruder, 2 is a raw material mixing tank, 3 is a thermal decomposition tank, 4 is a heating furnace,
Reference numeral 5 denotes a catalytic cracking tank, 6 denotes a cooler for a pyrolysis oil vapor, a cleaning tower 7 as a primary dehydrochlorination device, and a line 8 for supplying NaOH to the cleaning tower 7 are further provided, and further according to the present invention. Dehydrochlorination tank 9 consists of thermal decomposition tank 3 and catalytic decomposition tank 5
It is located between and.

Using the same equipment, a plastic consisting of 40% polyethylene, 19% polypropylene, 36% polystyrene and 5% polyvinyl chloride was crushed to 5 to 20 mm and used.

Next, the crushed plastic is fed to the extruder 1
And quantitatively supplied at 30 kg / h, and the outlet temperature is 25
The mixture was kneaded and melted while being heated to 0 to 300 ° C. Next, the molten plastic in the extruder 1 is supplied to the raw material mixing tank 2 connected to the outlet side of the extruder 1 and directly heated by using the pyrolysis oil refluxed from the pyrolysis tank 3 in the subsequent stage to obtain 280 Heated to ~ 320 ° C. In the melting process, about 90% of the halogen compounds already contained in the plastic are desorbed from the plastic and are generated in a gaseous state, so that these hydrogen chlorides are transferred from the extruder l, the raw material mixing tank 2 to the cleaning tower 7. It was led, washed and neutralized with an aqueous NaOH solution supplied from the nozzle 8. Then, a mixture of this molten plastic and pyrolysis oil is supplied to the pyrolysis tank 3,
380-420 by circulating between the heating furnace 4
The temperature was raised to ° C. By the operation up to this point, about 26 kg / h of pyrolysis oil vapor was generated from the pyrolysis tank 3. The particles of the pyrolyzed oil vapor shown in Table 1 were introduced into a dehydrochlorination tank (dechlorination tank) 9 having a packing structure shown in FIG. Then, the pyrolyzed oil vapor discharged from the dehydrochlorination tank 9 was condensed by the cooler 6 to collect the pyrolyzed oil.

The treatment using each particle was continuously performed for 7 days.

[0017]

[Table 1] When the particle size of the coarse particles shown in Table 1 is 20 mm or less, sufficient voids cannot be obtained, and clogging easily occurs due to attachment of the mist-like undecomposed component. If it is 30 mm or more, the voids become too large, and the undecomposed mist-like components reach the fine CaO layer through the voids, causing adhesion and blockage. If the particle size of the fine particles is 2 mm or less, the pressure loss in the dechlorination tank becomes large, and if it is 10 mm or more, a sufficient contact area between the pyrolyzed oil vapor and CaO cannot be obtained, and the dechlorination tank is enlarged. There is a need to. Therefore, the particle size of each particle is preferably within the above range.

Coarse-grained Al ₂ O ₃ shown in Table 1 has no chemical activity, and is expected only for the rectifying effect of the pyrolyzed oil vapor and for preventing the mist-like pyrolyzed oil from adhering and clogging.

Coarse-grain CaO is expected to have a dehydrochlorination effect due to the reaction of the coarse-grain itself with hydrogen chloride in addition to the above effects.

As shown in FIG. 2, Table 2 shows the changes over time in the coarse particle layer height and the differential pressure in each example when the inorganic coarse particles are arranged on the CaO inlet side and the CaO inlet side, respectively. Shown in.

[0021]

[Table 2] In all examples, the height of the fine particle layer is 970 mm.

In FIG. The change with time of the differential pressure between the inlet side and the outlet side of the dechlorination tank in 1-4 is shown. In FIG. 4, N
o. The change over time of the differential pressure between the inlet side and the outlet side of the dechlorination tank in 5 to 9 is shown. When the height of the coarse particle layer on the inlet side was set to 20 mm, a rapid increase in pressure loss was observed from the 6th day after starting the injection of plastic. When the height of the coarse grain layer was 50 mm, a slight increase in pressure loss was observed from the 6th day,
It didn't hinder driving. Coarse layer height 10
When it was set to 0 mm and 120 mm, almost no change in pressure loss with time was observed, and the pressure loss remained almost constant.

The pressure of the pyrolysis oil vapor at the inlet of the dechlorination tank is the pressure generated by the pyrolysis oil vapor (about 1500 mmA).
q), and it is desirable that the pressure loss in the dechlorination tank is 200 to 300 mmAq for stable operation. From the above results, it can be said that a coarse particle layer having a height of 50 mm or more needs to be provided on the inlet side of the packed bed so that the pressure loss of the dechlorination tank does not hinder stable operation. Also,
It can be said that the upper limit of the height of the coarse particle layer should be 100 mm, because there is almost no difference in the change over time in the pressure loss when the height of the coarse particle layer is 100 mm and when it is 120 mm.

Further, the coarse particle layer on the outlet side may be appropriately determined depending on the flow rate of the pyrolyzed oil vapor in the dechlorination tank, the degree of frictional powdering when filling fine-grained CaO, and the like. In this case, the inorganic coarse particle tank may have a size of at least 38 mm or more.

Table 3 shows the hydrogen chloride concentration in the vapor on the inlet side and the outlet side of the dechlorination tank in each example.

[0026]

[Table 3] As is clear from Table 3, the dehydrochlorination efficiency decreases when the coarse particle layer is not provided (Comparative Example 5). When a coarse particle layer having a layer height of 20 mm and low stability of ventilation resistance is used, the dehydrochlorination efficiency is relatively low, but the layer height is 50%.
It can be said that there is not much difference in dehydrochlorination efficiency in the case of mm to 120 mm.

Further, when CaO is used as the coarse particles, a higher dehydrochlorination efficiency is obtained than when Al ₂ O ₃ is used. From this, it was confirmed that the dehydrochlorination effect by coarse-grained CaO was also obtained.

Although no catalytic cracking catalyst was used in this example, when a coarse particle layer having a height of 50 to 100 mm was not provided,
Acceleration of poisoning of the catalytic cracking catalyst is sufficiently expected, and as a result, lowering of the yield of low boiling point components and incorporation of hydrogen chloride into the hydrocarbon oil are also sufficiently expected.

[0029]

The present invention has the following effects.

(1) By stabilizing the ventilation resistance of the dehydrochlorination tank, long-term continuous stable operation can be achieved.

(2) By preventing clogging and uneven flow in the dehydrochlorination tank, the dechlorination effect can be stabilized.

(3) The quality of hydrocarbon oil can be improved by obtaining a stable dehydrochlorination effect.

(4) By preventing frequent blockage and replacement of the CaO agent, the amount of CaO agent used can be reduced, leading to a reduction in running cost.

[Brief description of drawings]

FIG. 1 is a schematic diagram of oiling equipment provided with a dehydrochlorination tank of the present invention.

FIG. 2 shows an arrangement state of a coarse particle layer in the dehydrochlorination tank of the present invention.

FIG. 3 is a processing flow chart in conventional equipment for oil treatment of waste plastic.

FIG. 4 is a diagram showing changes over time in pressure loss in the dehydrochlorination tanks of Examples 1 to 4.

5 is a diagram showing changes over time in pressure loss in the dehydrochlorination tank in Examples 5 to 8 and Comparative Example 1. FIG.

[Explanation of symbols]

1 Extruder 2 Raw material mixing tank 3 Pyrolysis tank
4 Heating furnace 5 Contact cracking tank 6 Cooler for pyrolysis oil vapor
7 Washing tower 8 NaOH supply line 9 Dehydrochlorination tank

 ─────────────────────────────────────────────────── --- Continuation of the front page (72) Inventor Hitoshi Ohno 46-59 Nakahara, Tobata-ku, Kitakyushu, Fukuoka Prefecture 46-59 Nippon Steel Corporation Machinery & Plant Division

Claims (2)

[Claims] 1. A raw material mixing tank for melting a waste plastic material, a pyrolysis tank for thermally decomposing the melted plastic, and a dehydrochlorination tank for removing chlorine in the pyrolysis oil vapor generated in the pyrolysis tank. , And the dehydrochlorination tank in an oil treatment facility for waste plastic material, which is subsequently constituted by a catalytic cracking tank for reforming the pyrolysis vapor, at least on the inlet side of the dehydrochlorination tank, Layer thickness is 5
Inorganic coarse particles having a particle diameter of 0 to 100 mm and a particle diameter of 20 to 40 mm are arranged, and a CaO layer having a particle diameter of 2 to 10 mm is arranged on the downstream side of the inorganic coarse particle layer. Dehydrochlorination tank in oil treatment equipment. 2. Chemicals such as ceramics such as Al ₂ O ₃ and SiO ₂ , metals, glass, etc., in which the inorganic coarse particles do not deteriorate or deform at a temperature of 420 ° C. or lower which is the maximum temperature of the pyrolysis oil vapor. The dehydrochlorination tank in the oil treatment equipment for waste plastic materials according to claim 1, which is inorganic particles having no physical activity or coarse particles CaO which reacts with hydrogen chloride.