Search

CN-116670259-B - Carbon treatment section and depolymerization process associated therewith

CN116670259BCN 116670259 BCN116670259 BCN 116670259BCN-116670259-B

Abstract

A char treatment section is provided for operating on char containing a liquid slurry, consisting of a series of devices for progressive deagglomeration of the liquid slurry and drying of the char, which is finally collected and disposed of. The process and apparatus for char removal treatment and disposal so configured are very flexible and they allow operation in a continuous mode without the need to stop the depolymerization reactor.

Inventors

  • N Alishendefeinidi
  • D cloth Rita
  • A. Mazuko

Assignees

  • 巴塞尔聚烯烃意大利有限公司

Dates

Publication Date
20260505
Application Date
20211221
Priority Date
20201222

Claims (13)

  1. 1. A char processing device, comprising: -a first jacket chamber (6 a) provided with an inlet conduit (6 a-1) for feeding the char-containing slurry and a stirring system (6 b) capable of operating in the temperature range of 350-570 ℃, and further provided with a conduit (6 b-1) for discharging gaseous effluent, and -Means (6 c) for discharging concentrated slurry from the first jacket chamber (6 a) and delivering it to the second stripping chamber (6 d), capable of maintaining said slurry within the same temperature range as the first jacket chamber (6 a), and provided with a degassing system for removing gaseous effluents and producing discharged char; -a second stripping chamber (6 d) receiving the discharged char, equipped with a stirring system (6 d-1), a char outlet (6 d-2), a gas inlet (6 d-3) located at the bottom of the second stripping chamber (6 d), and a gas outlet (6 d-4) for removing gaseous effluent stripped from the discharged char; -means (6 e) for receiving the dry char of the second stripping chamber (6 d) and transporting it to a third collection chamber (6 f), capable of maintaining said dry char in a temperature range of 60-100 ℃; -a third collection chamber (6 f) receiving the dry char, provided with a stirring system (6 f-1), an outlet for char disposal operated by a valve (6 f-2).
  2. 2. A char treatment device according to claim 1, wherein the first jacket chamber (6 a) operates in a temperature range of 350-570 ℃.
  3. 3. A char treatment device according to claim 1, wherein the means for discharging the concentrated slurry from the first jacket chamber (6 a) and transporting it to the second stripping chamber (6 d) is a screw conveyor, which is jacketed and operates within the same temperature range of the first jacket chamber (6 a).
  4. 4. A char treatment device according to claim 1, wherein molten solar salt circulates within the first jacket chamber (6 a) and the jacket of the screw conveyor.
  5. 5. A char handling apparatus according to claim 3, wherein the screw conveyor is constituted by two different conveyors connected to each other, a lower end of a first lifting screw conveyor (6 c-1) being integrated with a bottom of the first jacket chamber (6 a), an upper end thereof being positioned at a higher level with respect to the lower end, the first lifting screw conveyor (6 c-1) being connected to one end of a second screw conveyor (6 c-2), the other end of the second screw conveyor (6 c-2) being connected to an upper portion of the second stripping chamber (6 d).
  6. 6. A char treatment device according to claim 5, wherein both conveyors are jacketed and operate within said same temperature range of the first jacket chamber (6 a).
  7. 7. A char handling device according to claim 1, wherein the second stripping chamber (6 d) is provided with a nitrogen inlet at the bottom of the second stripping chamber (6 d) and an outlet at the top of the second stripping chamber (6 d) for delivering stripped gas to a condensing unit.
  8. 8. A char treatment device according to claim 1, wherein the bottom of the second stripping chamber (6 d) is provided with an outlet and a ball valve for discharging the dry char into a jacketed screw conveyor maintained at a temperature in the range of 60-100 ℃.
  9. 9. A char treatment device according to claim 1, wherein the jacketed screw conveyor is connected to a third collection chamber (6 f), in which third collection chamber (6 f) nitrogen circulation is maintained through a gas inlet (6 f-3) and a gas outlet (6 f-4).
  10. 10. The char treatment device of claim 1, connected to a depolymerization device, comprising: Feeding system waste plastic material comprising at least one screw extruder (1) which is heated at the melting temperature of the plastic material; A first depolymerization reactor (2) receiving molten plastic material, the first depolymerization reactor (2) being a continuous stirred tank reactor in which depolymerization occurs forming a gaseous effluent and a liquid effluent, the first depolymerization reactor (2) being provided with an outlet for directing at least a portion of the liquid effluent produced in the first depolymerization reactor (2) to a char treatment section (6) and an outlet for discharging the gaseous effluent from the first depolymerization reactor (2); A first condensing unit (3) receiving said gaseous effluent from the first depolymerization reactor (2), provided with means for transferring gaseous products to a second condensing unit (5) operating at a temperature lower than that of said first condensing unit and means for directing the liquid flow from said first condensing unit (3) to a second depolymerization reactor (4); -a second depolymerization reactor (4) being a continuously stirred tank reactor in which depolymerization takes place, forming a gaseous effluent and a liquid effluent, the second depolymerization reactor (4) being provided with a catalyst feed line, an outlet for guiding at least a portion of the liquid effluent produced in the second depolymerization reactor (4) to the first depolymerization reactor (2) and an outlet for discharging the gaseous effluent from the second depolymerization reactor (4) and guiding them to a second condensing unit (5).
  11. 11. A process for treating a char-containing slurry comprising -Introducing a char-containing slurry into a first jacket chamber (6 a) provided with a stirring system (6 b), operating said first jacket chamber (6 a) to a temperature range of 350-570 ℃, thereby generating and discharging a gaseous effluent and Discharging concentrated slurry from the first jacket chamber (6 a) and delivering it to the second stripping chamber (6 d) while maintaining the slurry within the same temperature range as the first jacket chamber (6 a), and removing gaseous effluent thus formed and producing discharged char; introducing the discharged char into a second stripping chamber (6 d), the second stripping chamber (6 d) being equipped with a stirring system (6 d-1), a char outlet (6 d-2), a gas inlet (6 d-3) at the bottom of the second stripping chamber (6 d), and a gas outlet (6 d-4) for removing gaseous effluent stripped from the discharged char; feeding the dry char obtained in the second stripping chamber (6 d) to a third collection chamber (6 f) while maintaining the dry char in a temperature range of 60-100 ℃; -discharging the dry char from the third collection chamber (6 f) through a valve (6 f-2) and disposing of it.
  12. 12. The process of claim 11, wherein the slurry has a carbon content of 10-50wt% relative to the total weight of the slurry.
  13. 13. The process of claim 11, wherein the char content of the slurry is 20-40wt% relative to the total weight of the slurry.

Description

Carbon treatment section and depolymerization process associated therewith Technical Field The present invention relates to the field of depolymerizing plastic waste materials into new products including hydrocarbon oils, which have valuable and useful properties. In one aspect, the present invention relates to a process and apparatus for treating char produced by the depolymerization process. Background The recognition that waste plastic materials have a negative impact on the environment and thus on the health of any form of life is rapidly increasing. One attempt to mitigate this effect is to recycle plastic materials from household and industrial waste, with a portion of these materials re-entering the production cycle. This will involve further positive results such as the use of less fossil hydrocarbon sources to produce plastic articles. However, various factors suggest that this solution alone is insufficient to achieve the sustainability goal. In fact, the mechanical recycling of plastic materials generally results in substances of relatively low quality, relatively high cost, and which are cumbersome and unsuitable for urban waste in which certain plastics are mixed with various materials. Thus, most plastic waste is either used as a source of thermal energy in equipment such as incinerators, or simply stored in landfills, which, as described above, lead to degradation of the earth's environment by increasing CO 2 emissions and by releasing hazardous chemicals. In view of the foregoing, many attempts have been made in the past to effectively reprocess raw materials of waste plastics into liquid hydrocarbon products having valuable and useful properties, particularly as fuels. Thermocatalysis is a basic process whereby plastic waste material is converted into liquid fuel (pyrolysis product) by thermal action and optionally catalytic degradation in the absence of oxygen. Plastic waste is typically first melted in a stainless steel chamber under an inert purge gas such as nitrogen. In a first thermal step, the chamber heats the molten material to a gaseous state, which is cracked to form hydrocarbon chains of variable length in a subsequent thermal catalytic step. The hot pyrolysis gas is then condensed in one or more condensers to produce hydrocarbon distillates (pyrolysis oils) including straight and branched chain aliphatic, cycloaliphatic, and aromatic hydrocarbons. Depending on the composition, the resulting mixtures are used in a variety of applications, but in any case the requirements of product consistency and quality must always be met. The quality consistency of the recovered oil is difficult to be satisfied due to the unstable components of the plastic waste raw materials. Despite the use of catalysts and severe conditions, the depolymerization reaction produces as a by-product a substantial amount of viscous carbonaceous material in the form of carbon, which also includes non-organic materials derived from plastics or additives contained in the depolymerization catalyst. Due to tackiness, char adheres to the reactor walls and reduces the heat transfer coefficient, thereby also reducing process productivity and efficiency. Therefore, the generated char must be removed to maintain process operability. Industrial pyrolysis or thermocatalytic devices may have two pyrolysis chambers, referred to as a dual chamber system, that operate in parallel at approximately equal rates. When the two chambers are in unison to complete pyrolysis of the waste material, each chamber must be waited for cooling before removing char from the inner substrate of each chamber. In a variant, the chambers may operate in an alternating mode, such that when one is in the cleaning process, the other is in operation. However, by this method, the amount of plastic treated per unit time decreases. In order to avoid the cleaning step of the deaggregation chamber, one technical solution is to drain the content of the deaggregation chamber while the content of the deaggregation chamber is still in the form of a slurry rather than a solid viscous substance. The slurry form, particularly if the char content in the slurry is not highly concentrated, allows the char to not adhere or adhere to the reactor wall to a limited extent. However, the relatively dilute slurry extracted from the reactor has a high content of hydrocarbon chains, which still requires depolymerization in order to produce pyrolysis products with a suitable and acceptable productivity. Thus, the char treatment section needs to be configured in a manner that is capable of treating the large amount of effluent from which the char is extracted and the depolymerization reactor is completed. In view of the foregoing, an object of the present invention is directed to a char treatment section capable of receiving and treating a liquid effluent containing char in slurry form. Disclosure of Invention Accordingly, an aspect of the present invention discloses a char trea