COLUMN

FIELD

5 The application relates to a method defined in claim 1 and a process arrangement defined in claim 11 for treating a feed before a quench column in an integrated process. Further, the application relates to a use of the method defined in claim 17. 0

BACKGROUND

Known from the prior art is to produce ole fins from fossil raw material by a cracking process, such as by a steam cracking process. 5 Further, it is known from the prior art that waste plastic is difficult to recycle and to utilize as raw material in new products. Mechanical recycling is the cheapest way to recycle the waste plastic. The mechanically recycled plastic is typically used in0 lower level applications.

OBJECTIVE

The objective is to solve the above problems. Further, the objective is to disclose a new type of5 method and process arrangement for treating a feed be fore a quench column in a cracking process. Further, the objective is to recover olefins from polyolefins and recycle plastics. Further, the objective is to im prove an integrated process comprising the cracking0 unit and a gasifier unit.

SUMMARY

The method and process arrangement and use are characterized by what are presented in the claims.5 In the method and process arrangement, a feed is treated before a quench column in an integrated process comprising at least a gasifier for forming a gasifier flow, a cracking furnace for forming a crack er flow and a quench column for treating the feed com prising the gasifier and cracker flows, and the gasi fier flow is combined to the cracker flow to form the feed, and temperature of the feed is controlled to a predetermined temperature before the quench column.

BRIEF DESCRIPTION OF THE DRAWING

The accompanying drawings, which are included to provide a further understanding of the invention and constitute a part of this specification, illus trate some embodiments of the invention and together with the description help to explain the principles of the invention. In the drawings:

Fig. 1 is a flow chart illustration of a pro cess according to one embodiment,

Fig. 2 is a flow chart illustration of a pro cess according to another embodiment,

Fig. 3 is a flow chart illustration of a pro cess according to another embodiment, and

Fig. 4 is a flow chart illustration of a pro cess according to another embodiment.

DETAILED DESCRIPTION

In the method a feed is treated before a quench column in an integrated process. The integrated process comprises at least one gasifier for forming a gasifier flow by a gasification, at least one cracking furnace, e.g. a steam cracking furnace, for forming a cracker flow, at least one quench column for treating the feed comprising the gasifier flow and cracker flow and at least one transfer line to supply the feed to the quench column. The method comprises cooling at least partly the gasifier flow for killing chemical reactions after the gasification, cooling at least partly the cracker flow after the cracking furnace, combining the gasifier flow to the cracker flow before a transfer line valve of the transfer line to form the feed to the quench column, and controlling temperature of the feed to a predetermined temperature of the transfer line before the quench column. The transfer line comprises at least one transfer line valve (11), and the gasifier flow (3) is combined with the cracker flow (4) before the transfer line valve in the trans fer line.

In this context, the transfer line means any transfer line between any cracking furnace and any quench column. The transfer line can comprise at least one, or more, transfer line of the cracking furnace and a main transfer line. The cracker flows from the transfer lines of the cracking furnaces are collected to the main transfer line, and the formed feed is sup plied to the quench column via the main transfer line. At least one of the transfer lines comprises at least one transfer line valve. In one embodiment, the trans fer line valve is arranged before the main transfer line or between the transfer line of the cracking fur nace and the main transfer line. The transfer line valve is a valve, which is used to isolate the crack ing furnace from the main transfer line. In one embod iment, the transfer line valve is used to isolate the cracking furnace from the common transfer for decoking of furnace tubes and transfer line heat exchangers. When the gasifier flow is combined to the cracker flow before the transfer line valve, the gasifier can be integrated to a cracker unit easily and without prob lems in the whole cracking process. In one embodiment, the transfer line valve can be operated by opening and closing the valve. In one embodiment, a line between the gasifier and the transfer line comprises a valve, which can be opened and closed. Then, the line from the gasifier can be opened by opening the valve and the gasifier flow can be combined to the cracker flow, or alternatively, the valve can be closed and the gas ifier flow is not combined with the cracker flow.

A process arrangement, i.e. an apparatus, for treating a feed before a quench column in connection with an integrated process comprises at least one means for cooling at least partly the gasifier flow for killing chemical reactions after the gasification, a cooling system for controlling temperature of the feed to a predetermined temperature of the transfer line before the quench column, and at least one con nection point in the transfer line where the gasifier flow is combined to the cracker flow to form the feed to the quench column. The cooling system comprises at least one cooling device for cooling at least partly the cracker flow after the cracking furnace. The transfer line comprises at least one transfer line valve (11) and the connection point is located before the transfer line valve. In one embodiment, the con nection point is located before the transfer line valve in the transfer line from the cracking furnace to the main transfer line. The integrated process com prises at least one gasifier for forming a gasifier flow, at least one cracking furnace for forming a cracker flow, at least one quench column for treating the feed comprising the gasifier flow and cracker flow and at least one transfer line to supply the feed to the quench column.

Some embodiments of the method and the process arrangement are shown in Figs. 1 - 4.

In the integrated process, at least one gasi fier unit comprising the gasifier or gasifiers is in terconnected to the cracker unit, e.g. an olefin cracker unit. The cracker unit may be a steam cracker unit. The cracker unit comprises at least one cracking furnace, at least one quench column and at least one transfer line for supplying the feed to the quench column. In this context, the quench column means any quench column, for example a quench column in a main quench unit or fractionation unit, a first quench col umn in a main quench unit or fractionation unit, a main quench column, a main quench tower or a primary fractionation device of the fractionation unit. Fur ther, the cracker unit comprises at least one cooling device to cool the gas of the cracking before the quench column. The connection of the gasifier unit is ideally executed to the main transfer line located in between the cracking furnaces and the quench column of the cracker unit. If such a connection is not availa ble, it is possible to integrate the gasifier unit within the boundaries of the cracking furnace. The downstream facilities of the cracker can then separate the valuable components formed in the gasifier and thereby reduce the consumption of fresh feed to the cracker for any given olefin production level. Typi cally, the process conditions of the outlet of the gasifier must meet the requirements at the cracker unit. In one embodiment, pressure is typically low 1-3 bar (g) and temperature around 200-250 °C. As the flow rate from the gasifier is very low compared to the cracker transfer line flow, cooling can be achieved by an internal mixing inside the transfer line, thereby not requiring additional quenching within the gasifier unit than killing the chemical reactions after the gasification. When the connection is done within the cracking furnace boundaries, a secondary cooling de vice, e.g. a secondary quench exchanger, of the crack ing unit and a direct injection of the desired quench to control the temperature can be used to meet the re quired cracker conditions.

In this context, the gasification in a gasi fier (1) means any gasification process by steam. The gasification is a process that converts starting mate rial into gasification products, in this context into gasifier flow. This is achieved by treating the start- ing material at suitable temperatures, with a con trolled amount of steam. In one embodiment, the gasi fication is carried out at 680 - 750 °C. Any suitable gasifier may be used in the present process. In one embodiment, the gasifier is a vertical fluidized bed gasifier. In one embodiment, the fluidized bed is an inert bed in the gasifier.

The starting material in the gasification may be any suitable material. The gasifier flow may be formed from plastic waste comprising polyolefins and/or recycled plastics in the gasifier. In one em bodiment, the plastic waste is recycled plastics. In this context, the recycled plastics means any plastic mixture which consists of one or more polymers. The re- cycled plastics may comprise polyolefins, e.g. poly ethylene or polypropylene, and other polymers, and further other components, such as paper, cardboard and/or aluminium material. In one embodiment, the re cycled plastics may comprise also PVC plastic. In this context, the gasifier flow (3) means any flow, e.g. gas, product or the like, formed in the gasifier. In one embodiment, the gasifier flow is gas. The gasifier flow comprises olefins, e.g. ethylene and propylene, and the gasifier flow may be rich in ole- fins. Further, the gasifier flow may comprise aromat ics, e.g. benzene and toluene, and other hydrocarbons, e.g. butadiene. Usually, the gasifier flow is a mix ture of hydrocarbons.

In the cracking furnace (2), the cracker flow is formed. The reactions may be carried out, for exam ple at 750 - 900 °C in the furnace, in which reaction time is short, e.g. below 1 second. For example, in the gasifier, the residence time may be below 10 sec onds, in one embodiment 1 - 10 seconds and in one em- bodiment 3 - 10 seconds.

In this context, the cracker flow (4) means any flow, e.g. gas, product or the like formed in the cracking furnace (2). In one embodiment, the cracker flow is gas. The cracker flow comprises olefins, and typically the cracker flow is rich in olefins. Fur ther, the cracker flow may comprise other hydrocarbons and/or components.

In one embodiment, the gasifier flow (3) is fed to the transfer line (10) and combined with the cracker flow (4) to form the feed (5) to the quench column (6). In one embodiment, the gasifier flow is combined to the cracker flow in the transfer line. In one embodiment, the transfer line is located between the cracking furnace and the quench column. The trans fer line is arranged to transfer the cracker flow (4) and the feed (5) to the quench column.

The gasifier flow from the gasifier can be connected to the cracker flow at different process lo cations. For example, either within premises of the operating cracking furnace or directly to the transfer line connecting to the quench column. As the flow rate of the gasifier flow is low compared to the cracker flow, the cooling can be achieved by an inline mixing and thereby not requiring any additional cooling equipment for the gasifier flow at all.

In one embodiment, the process arrangement comprises one or more connection points. In one embod iment, the process arrangement comprises more than one connection points, and the desired connection point can be used to combine the gasifier flow to the crack er flow. In this context, the connection point may be any connection point, feed point, connection, cou pling, tie-in or the like, by which the gasifier unit can be connected to the cracker unit. In one embodi ment, the connection point is located in connection with the transfer line for combinining the gasifier flow (3) to the cracker flow (4) in the transfer line before a transfer line valve (11) in the transfer line. In one embodiment, the connection point is in connection with the transfer line. In one embodiment, the connection point is after the cooling device (8a,8b) of the cracker flow, such as after a primary cooling device or after primary and secondary cooling devices.

In one embodiment, the gasifier flow (3) is combined to the cracker flow (4) to form the feed (5) and the feed (5) is cooled after the combining. In one embodiment, the gasifier flow (3) is combined to the cracker flow (4) to form the feed (5) without cooling of the feed (5) after the combining. In one embodiment, the gasifier flow (3) is combined to the cracker flow (4) after the first cooling device, e.g. a primary cooling device. In one embodiment, the formed feed is cooled after the first cooling device.

In one embodiment, the cooling system is ar ranged to fulfil the design temperature of the trans fer line connected to the quench column (6). In one embodiment, temperature of the feed is arranged below 250 °C before the quench column. In one embodiment, the temperature of the feed is below 220 °C before the quench column. In one embodiment, the temperature of the feed is 200 - 250 °C, in one embodiment 200 - 220 °C, before the quench column

In one embodiment, reactions are killed rap idly after the gasification by cooling the gasifier flow (3) to temperature of below 600 °C, in one embod iment below 550 °C, in order to stop chemical reac tions. Then the yield of targeted products, e.g. light olefins, may be increased or maximised.

In one embodiment, reactions are killed after the cracking furnace by cooling the cracker flow (4) to temperature of below 600, in one embodiment 500 - 600 °C, and in one embodiment 550 - 600 °C, in order to stop chemical reactions. In one embodiment, the cracker flow (4) is cooled to temperature of 400 - 550 °C, in one embodiment 400 - 500 °C, before the combin- ing. In one embodiment, the cracker flow (4) is cooled in few steps to temperature which is below 250 °C be fore the combining. In one embodiment, the cracker flow (4) is cooled to temperature of 200 - 250 °C, in one embodiment 200 - 220 °C, before the combining.

In one embodiment, the cooling system com prises at least one cooling device (8a,8b) for cooling the cracker flow (4) and/or the feed (5). In one em bodiment, the cooling system comprises at least two cooling devices, e.g. primary and secondary cooling devices, for cooling the cracker flow (4) and/or the feed (5). In one embodiment, the cooling system com prises at least two cooling devices, e.g. primary and secondary cooling devices, for cooling the cracker flow (4) after the cracking furnace (2) and before the combining to a desired temperature. In one embodiment, the cooling system comprises at least one cooling de vice, e.g. a primary cooling device, for cooling the cracker flow (4) and at least one cooling device, e.g. a secondary cooling device, for cooling the feed (5) after the combining. In one embodiment, at least one cooling device is a quench exchanger. In one embodi ment, the primary cooling device is a primary quench exchanger and the secondary cooling device is a sec ondary quench exchanger.

In one embodiment, the gasifier flow (3) is cooled before the combining. In one embodiment, the process arrangement comprises at least one cooling de vice (7), e.g. a water quench or heat exchanger, in the gasifier unit, before the combining, for cooling the gasifier flow after the gasifier (1) to a desired temperature. In one embodiment, the cooling device of the gasifier unit is a water quench. In one embodi ment, the cooling device of the gasifier unit is a heat exchanger.

In one embodiment, the gasifier flow (3) is fed to the cracker flow at temperature of 400 - 550 °C, in one embodiment 400 - 500 °C. In one embodiment, the gasifier flow (3) is cooled to temperature of 400 - 600 °C, in one embodiment 450 - 550 °C, before the combining. In one embodiment, the gasifier flow (3) is cooled to temperature of 200 - 250 °C before the com bining.

In one embodiment, the feed (5) is cooled af ter the combining.

In one embodiment, the gasifier flow (3) is combined to cracker flow (4) in the transfer line and the cooling of the gasifier flow can be achieved by an internal mixing inside the transfer line. The gasifier flow may be cooled by means of the cracker flow when the gasifier flow is combined to the cracker flow be- cause the cracker flow is huge compared to the gasifi er flow.

In one embodiment, the process arrangement comprises at least one cooling device (7) for cooling at least partly the gasifier flow (3) after the gasi- fier (1) and at least one cooling device (8a,8b) for cooling at least partly the cracker flow (4) after the steam cracker (2).

In one embodiment, the feed (5) or the crack er flow (4) is cooled by a direct quench (12) by in- jection of water and/or oil. In one embodiment, the direct injection of the quench is arranged to control the temperature in the feed or in the cracker flow. In one embodiment, the existing quench rate can be in creased to compensate for the additional heat from the gasifier. In one embodiment, the process arrangement comprises at least one direct quench by which the feed (5) or the cracker flow (4) is cooled by injection of water and/or oil. Any suitable direct quench may be used. When gasifier (1) is connected within the crack- ing furnace (2), the furnace direct quench system will be able to also cool the gasifier flow, if the con trolling temperature is measured from a downstream of the gasifier connection point. In one embodiment, the water and/or oil may be recirculated to the direct quench, e.g. from the quench column or another quench device. In one embodiment, the cracker flow and/or the feed is cooled by the direct quench after the cooling of the cracker flow and/or feed. In one embodiment, the injection of direct quench is arranged after the cooling devices of the cracker flow and/or the feed.

In one embodiment, other cracking furnaces (13) may be connected to the transfer line (10). In one embodiment, at least one additional cracking fur nace, in which the cracker flow is cooled at least partly, may be connected to the transfer line after the cooling devices (8a,8b).

Possible contaminants of the gasifier flow may be diluted when the gasifier flow is combined to the cracker flow because the cracker flow is huge com pared to the gasifier flow. Mass flow of the cracker flow may be typically 20+ times higher than mass flow of the gasifier flow. Thus, a contaminant removal is not obligatory. In one embodiment, the gasifier flow is filtered after the gasification. In one embodiment, the gasifier flow is treated by dry scrubbing and fil tered. In one embodiment, temperature of the gasifier flow is 400 - 430 °C after the filtration.

After the quench column, the gas (9) may be compressed for a fractionation unit or treated in any other way.

The method and process arrangement are based on a continuous process.

In one embodiment, the method and process ar rangement can be used in a production of olefins, aro matics, e.g. benzene, toluene or other aromatics, oth er hydrocarbons, polymers, polyolefins or the like, in a production of products from recycled plastic waste, in a recycling of polyolefins back to light olefins, or their combinations. Thanks to the invention, the integration of the gasifier unit to an existing cracker unit can be improved and the integration can be performed easily without a shutdown of the whole cracking process. For example, an additional pre-quench is not needed to cool the gasifier flow. Further, this process allows some impurities in the produced gasifier flow.

The method and process arrangement offer a possibility to produce olefins and polyolefins easily, and energy- and cost-effectively. The present inven tion provides an industrially applicable, simple and affordable way to produce desired products from dif ferent starting materials. The method and process ar rangement are easy and simple to realize in connection with production processes.

Further, the recycling of plastics can be im proved by means of the invention. Recycled materials can be treated and utilized easily and effectively. In this process waste materials can be upgraded.

EXAMPLES

Figs. 1 - 4 present some embodiments of the process for treating a feed before a quench column in connection with an integrated process.

The integrated process comprises at least one gasifier (1) for forming a gasifier flow (3), at least one cracking furnace (2) for forming a cracker flow (4), at least one quench column (6) for treating the feed (5) comprising the gasifier flow (3) and the cracker flow (4) and at least one transfer line (10) to supply the feed to the quench column.

The process arrangement of Fig. 1 comprises means for cooling at least partly the gasifier flow (3) for killing chemical reactions after the gasifica tion in the gasifier (1). Further, the process ar rangement comprises a cooling system for controlling temperature of the feed (5) to a predetermined temper- ature of the transfer line before the quench column (6). Further, the process arrangement comprises at least one connection point where the gasifier flow (3) is combined to the cracker flow (4) to form the feed (5) to the quench column. The cooling system comprises at least one cooling device (8,8a,8b) for cooling at least partly the cracker flow (4) after the cracking furnace (2). The connection point is located between the cooling device in which the cracker flow is cooled at least partly after the cracking furnace and the quench column. In one embodiment, the gasifier flow (3) may be cooled by a cooling device (7) after the gasifier (1) and before the combining to the cracker flow (4). In one embodiment, the cracker flow (4) may be cooled by at least two cooling devices (8) after the cracking furnace (2) and before the combining. In one embodiment, the cracker flow (4) may be cooled by a primary cooling device (8a) after the cracking fur nace (2), and after that the gasifier flow (3) is com bined to the cracker flow (4) to form the feed (5) and the feed is cooled by a secondary cooling device (8b). The temperature of the feed (5) is arranged below 250 °C before the quench column (6).

The process arrangement of Fig. 2 comprises means for cooling at least partly the gasifier flow

(3) for killing chemical reactions after the gasifica tion in the gasifier (1). The reactions are killed rapidly by cooling the gasifier flow (3) to tempera ture of below 600 °C in order to stop chemical reac tions. Further, reactions of cracking are killed after the cracking furnace (2) by cooling the cracker flow

(4) to temperature of below 600 °C in order to stop chemical reactions. Further, the process arrangement comprises a cooling system for controlling temperature of the feed (5) to a predetermined temperature of the transfer line before the quench column (6). Further, the process arrangement comprises at least one connec- tion point where the gasifier flow (3) is combined to the cracker flow (4) to form the feed (5) to the quench column. The cooling system comprises at least two cooling devices (8a,8b), e.g. primary and second ary quench exchangers, for cooling the cracker flow

(4) after the cracking furnace (2) to temperature of

200 - 250 °C. The connection point is located after the cooling devices (8a,8b) in which the cracker flow is cooled. The gasifier flow (3) is combined to the cracker flow (4) in the transfer line (10). The trans fer line comprises a transfer line valve (11), the gasifier flow (3) is combined to the cracker flow (4) before the transfer line valve (11). The gasifier flow (3) may be cooled by at least one cooling device (7), e.g. a heat exchanger and/or water quench, after the gasifier (1) and before the combining to the cracker flow (4) to a temperature of 200 - 250 °C. Alterna tively, the gasifier flow (3) is combined to cracker flow (4) in the transfer line and at least a part of the cooling of the gasifier flow can be achieved by an internal mixing inside the transfer line. Then the gasifier flow (3) may be fed to the cracker flow at temperature of 400 - 500 °C or at temprerature which is below 400 °C, e.g. below 250 °C. Further, the pro cess arrangement may comprise at least one direct quench (12) by which the cracker flow (4) or feed (5) is cooled by injection of water and/or oil. The tem perature of the feed (5) is arranged below 250 °C be fore the quench column (6). A gas stream (9) is dis charged from the quench column.

The process arrangement of Fig. 3 comprises means for cooling at least partly the gasifier flow (3) for killing chemical reactions after the gasifica tion in the gasifier (1). The reactions are killed rapidly by cooling the gasifier flow (3) to tempera ture of below 600 °C in order to stop chemical reac tions. Further, reactions of cracking are killed after the cracking furnace (2) by cooling the cracker flow (4) to temperature of below 600 °C in order to stop chemical reactions. Further, the process arrangement comprises a cooling system for controlling temperature of the feed (5) to a predetermined temperature of the transfer line before the quench column (6). Further, the process arrangement comprises at least one connec tion point where the gasifier flow (3) is combined to the cracker flow (4) to form the feed (5) to the quench column. The cooling system comprises at least two cooling devices (8a,8b). The cracker flow (4) is cooled after the cracking furnace (2) by a primary cooling device (8a), e.g. primary quench exchanger, to temperature of 400 - 500 °C. After that the gasifier flow (3) is combined to the cracker flow (4) to form the feed (5). The gasifier flow (3) is fed to the cracker flow at temperature of 400 - 500 °C. In one embodiment, the gasifier flow (3) may be cooled by a cooling device after the gasifier (1) and before the combining to the cracker flow (4). The formed feed (5) is cooled by a secondary cooling device (8b), e.g. e.g. secondary quench exchanger. The temperature of the feed (5) is arranged below 250 °C before the quench column (6). A gas stream (9) is discharged from the quench column. The transfer line comprises a transfer line valve (11), the gasifier flow (3) is combined to the cracker flow (4) before the transfer line valve (11).

The process arrangement of Fig. 4 comprises means (14) for cooling at least partly the gasifier flow (3) for killing chemical reactions after the gas ification in the gasifier (1). The reactions are killed rapidly by cooling the gasifier flow (3) to temperature of below 600 °C in order to stop chemical reactions. Further, reactions of cracking are killed after the cracking furnace (2) by cooling the cracker flow (4) to temperature of below 600 °C in order to stop chemical reactions. Further, the process arrange ment comprises a cooling system for controlling tem perature of the feed (5) to a predetermined tempera ture of the transfer line (10) before the quench col umn (6). Further, the process arrangement comprises two connection points, where the gasifier flow (3) can be combined to the cracker flow (4) to form the feed (5) to the quench column. The cooling system comprises at least one cooling device (8a) or alternatively two cooling devices (8a,8b), e.g. primary and secondary quench exchangers, for cooling the cracker flow (4) and/or feed (5) to temperature of 200 - 250 °C. The connection points (B,C) are located in connection with the transfer line for combinining the gasifier flow (3) to the cracker flow (4) in the main transfer line, after two cooling devices (8a, 8b) and before a trans fer line valve (11) in the transfer line (B), or after the primary cooling device (8a) of the cracker flow and before a transfer line valve (11) in the transfer line (C). The gasifier flow (3) is combined to the cracker flow (4) in the desired connection point (B,C). The gasifier flow (3) may be cooled by at least one cooling device (7), e.g. a heat exchanger and/or water quench, after the gasifier (1) and before the combining to the cracker flow (4) to a temperature of 200 - 250 °C. The gasifier flow (3) can be combined to cracker flow (4) in the transfer line before the transfer line valve (11) (B), e.g. to an upstream of the transfer line valve. In one embodiment, a part of the cooling of the gasifier flow can be achieved by an internal mixing inside the transfer line. Further, the gasifier flow (3) can be combined to cracker flow (4) at connection point C after the primary cooling device (8a) such that the cracker flow (4) is cooled after the cracking furnace (2) by the primary cooling device (8a) to temperature of 400 - 500 °C and after that the gasifier flow (3) is combined to the cracker flow (4) to form the feed (5). The formed feed (5) may be cooled by a secondary cooling device (8b). The gasifi er flow (3) is fed to the cracker flow at temperature of 400 - 500 °C. Further, the process arrangement com- prises at least one direct quench (12) by which the cracker flow (4) or feed (5) is cooled by injection of water and/or oil. Another cracking furnace (13) in which the cracker flow has been cooled at least partly may be connected to the transfer line (10) after the cooling devices (8a,8b). The temperature of the feed

(5) is arranged below 250 °C before the quench column

(6). A gas stream (9) is discharged from the quench column. Any suitable devices and equipments can be used in the process of these examples.

The method and process arrangement are suita ble in different embodiments for producing olefins, polyolefins and other hydrocarbons from different starting materials.

The invention is not limited merely to the examples referred to above; instead many variations are possible within the scope of the inventive idea defined by the claims.