JP5357761B2 - Methods for promoting olefin production - Google Patents

Abstract

A processing scheme and arrangement for enhanced olefin production involves cooling or treating an olefin cracking reactor effluent stream (12) by contacting the olefin cracking reactor effluent stream with a quench oil stream (18) in a single contact cooler contact zone (14) to produce a cooled vapor stream (20) and to form a heated quench oil stream (22). A pressure differential across the single contact cooler is less than 3.5 kPa. The heated quench oil stream can be subsequently cooled and returned to the single contact cooler.

Description

  The present invention relates generally to the production of light olefins, and more particularly to the production of light olefins by cracking of heavy olefins.

  A major part of the global petrochemical industry is the production of light olefin materials and the production of many important chemical products by subsequent polymerization, oligomerization, alkylation and other well-known chemical reactions. Related to the use of the substance. Light olefins include ethylene, propylene and mixtures thereof. These light olefins are indispensable building blocks for the modern petrochemical and chemical industries.

  Light olefins can be produced from other olefins using olefin conversion techniques. Such olefin conversion processes can be combined with or integrated with other olefin production technologies such as, for example, steam or fluid catalytic cracking or oxygenated compounds to olefins to increase light olefin production. There are also often.

In general, there are two main types of olefin conversion technologies that can be used to produce light olefins: metathesis and olefin cracking. Such a metathesis method usually produces propylene by reacting ethylene with 2-butene. Such olefin cracking processes typically produce ethylene and propylene by cracking or converting a C _{4 to} C ₈ feedstock, containing mainly C _{2 to} C ₆ compounds along with some hydrogen and other light gases. To produce a stream of effluent. Subsequently, such an effluent stream is separated into various product streams such as, for example, a product stream containing ethylene and propylene.

  Such treatment can desirably result in the formation of propylene and / or ethylene with increased relative amounts, but further improvements such as further increasing the relative amount of propylene and / or ethylene production and recovery. It has been desired and sought.

  In general, olefin cracking processes are carried out at elevated temperatures in the reactor and usually produce an effluent stream having a temperature above 500 ° C. Such olefin cracking reactor effluent streams are then cooled and compressed to facilitate separation into individual product streams. The olefin cracking reactor effluent stream can be cooled using a variety of heat exchange methods such as, for example, indirect heat exchange with a cooling medium such as cooling water. One such indirect heat exchange method involves passing the hot olefin cracking reactor effluent through a heat exchange device, such as a tube shell heat exchanger, suitable for efficient compression. It is generally involved to produce a cooled olefin cracking reactor effluent stream having a certain temperature distribution.

  However, such indirect heat exchange devices can be susceptible to fouling due to olefin cracking reactor effluent stream constituents. For example, heavy hydrocarbon compounds may condense on the surface of the heat exchange device and reduce the cooling capacity of the heat exchange device. In general, the temperature of the gas being compressed dominates the capacity of the associated compressor, i.e., the higher the gas temperature, the lower the degree to which the gas can be compressed. Therefore, when the cooling capacity of the heat exchanger decreases, the compression capacity of the associated compressor decreases, which in turn increases the interruption time for cleaning the heat exchanger and decreases the product output. Become.

  In view of the above, there is a need and demand for an effective processing scheme and / or equipment for reducing fouling of heat exchange equipment used to cool the olefin cracking reactor effluent stream.

  Moreover, the gaseous material passing through such indirect heat exchange devices can also experience a significant pressure drop from the inlet to the outlet, resulting in a cooled effluent stream having a lower pressure than may be desired. In order to compress the cooled effluent stream to a pressure suitable for further processing in subsequent separators, further energy consumption and increased compressor size may be required. Accordingly, there is a further need and demand for a processing scheme and / or apparatus that reduces the pressure loss across the heat exchange apparatus.

  In addition, the pressure drop across the heat exchanger can cause an increase in pressure at the outlet of the associated olefin cracking reactor, resulting in a decrease in the yield of ethylene and / or propylene produced by the olefin cracking process. There is. Accordingly, there is a still further need and demand for a processing scheme and / or equipment effective to increase the relative yield of light olefins, particularly ethylene and / or propylene.

It is a general object of the present invention to provide an improved method and system that results in increased yields of light olefins from an olefin rich feed stream.
A more specific object of the present invention is to overcome one or more of the problems described above.

  A general object of the present invention is to contact an olefin cracking reactor effluent stream and a quench oil stream in a single contact cooler contact zone to produce a cooled vapor (gas) stream, Olefin cracking reactor effluent stream that forms a heated quench oil stream and includes a pressure drop from the contact cooler inlet to the contact cooler outlet of less than 3.5 kPa (0.5 psi) Through the method of cooling, at least part can be achieved. Further, the method can include cooling the heated quench oil stream and returning a portion of the cooled oil stream to the contact cooler.

FIG. 2 is a simplified schematic diagram of a process for cooling an olefin cracking reactor effluent stream, according to one embodiment. FIG. 3 is a simplified schematic diagram of a process for treating an olefin cracking reactor effluent stream according to another embodiment.

  The prior art generally does not provide processing schemes and equipment that are as effective as desired in increasing the relative yield of light olefins compared to conventional olefin cracking and recovery processes. Further, the prior art generally does not provide a processing scheme and apparatus that reduces pressure loss across fouling and / or associated heat exchange devices as desired.

  According to another embodiment, a method of treating an olefin cracking reactor effluent stream includes the flow of olefin cracking reactor effluent by indirect heat exchange with the reactor feed stream in a first heat exchange zone. Cooling the stream to produce a cooled effluent stream having a temperature in the range of 150C to 210C. The process involves contacting the cooled effluent stream with a quench oil stream in a single packed bed contact cooler contact zone to provide a cooled steam having a temperature in the range of 25 ° C to 55 ° C ( It further includes generating a gas) stream to form a heated oil stream. The heated oil stream is mixed with the heavy oil feed stream to produce a composite heavy oil stream. At least a first portion of the composite heavy oil stream is returned to the cooling cooler to provide a quench oil stream.

According to yet another embodiment, a method for producing light olefins with increased yield from an olefin-rich feed stream comprises C _{4 to} C ₈ + olefins (C _{4 to} C ₈ or more carbon atoms). Introducing an olefin-rich feed stream comprising an olefin) into an olefin cracking reactor to produce an effluent stream comprising at least one of ethylene and propylene. The effluent stream is cooled by indirect heat exchange with the olefin-rich feed stream in the first heat exchange zone to produce a cooled effluent stream. The cooled effluent stream is brought into contact with the quench oil stream in a single packed bed contact cooler contact area to produce a cooled steam (gas) stream and the heated quench oil stream is And the pressure differential from the contact cooler effluent stream inlet to the cooled vapor (gas) stream outlet is less than 3.5 kPa (0.5 psi).

  The cooled vapor (gas) stream is separated into at least one lightweight stream comprising a light olefin selected from ethylene, propylene and combinations thereof. The heated quench oil stream is mixed with the heavy oil stream to produce a composite heavy oil stream. The composite heavy oil stream is cooled by indirect heat exchange with the cooling medium stream in the second heat exchange zone to produce a cooled oil stream. This first portion of the cooled oil stream is returned to the single packed bed contact cooler to provide a quench oil stream.

A system for the production of ethylene and propylene is also provided. This system provides at least a portion of a feed stream rich in C ₄ + olefins (olefins having C ₄ or more carbon atoms) to an olefin cracking reactor effluent stream comprising at least one of ethylene and propylene. An olefin cracking reactor for conversion is provided. The system is configured such that at least a portion of the olefin cracking reactor effluent stream contacts the quench oil stream in the contact zone to produce a cooled vapor (gas) stream to form a heated quench oil stream. A single layer contact cooler. The contact cooler has a pressure difference of less than 3.5 kPa (less than 0.5 psi) from the inlet of the olefin cracking reactor effluent stream to the outlet of the cooled vapor (gas) stream. The system also includes a heat exchanger in which the heated quench oil stream is cooled by indirect heat exchange with the cooling medium stream to form a cooled oil stream.

As used herein, reference to “light olefins” should be understood to refer generally to C ₂ and C ₃ olefins, ie, ethylene and propylene.

  Other objects and advantages will become apparent to those skilled in the art from the following detailed description when taken in conjunction with the appended claims and drawings.

A feed stream rich in C ₄ + olefins (olefins having C ₄ or more carbon atoms) is cracked in the reactor to produce C ₂ and / or C ₃ olefins, unconverted C _{4 to} C ₈ + hydrocarbons. (Hydrocarbons having C _{4 to} C ₈ or more carbon atoms), and aromatic hydrocarbons such as benzene and toluene, some more hydrogen, and other light gases such as methane, ethane and / or propane An olefin cracking reactor effluent stream containing various hydrocarbon products can be produced.

  At least a portion of such olefin cracking reactor effluent stream can then be cooled and separated to recover ethylene and / or propylene.

  FIG. 1 is designated generally by the reference numeral 10 and is a system for cooling or producing an increased relative amount of light olefins by cooling the olefin cracking reactor effluent stream, according to one embodiment. Apparatus) is schematically described.

  More specifically, in the system 10, the olefin cracking reactor effluent stream 12 is introduced into the contact cooler 14 below the single contact region 16. A quench oil stream 18 is introduced into the contact cooler 14 above the single contact region 16. This cracking reactor effluent stream 12 is contacted in a countercurrent fashion with a quench oil stream 18 in a single contact region 16 to produce a cooled vapor stream 20 and a heated quench oil stream 22. The material passing through the contact cooler 14 from the olefin cracking reactor effluent stream inlet 24 to the cooled vapor stream outlet 26 has a pressure drop (pressure drop) of less than 3.5 kPa (0.5 psi).

  According to certain embodiments, the olefin cracking reactor effluent stream 12 may be introduced into the contact cooler 14 at a gauge pressure (1-3 psig) of 7-21 kPa.

  The olefin cracking reactor effluent stream 12 may desirably have a temperature in the range of 120 ° C. to 210 ° C. (250 ° F. to 400 ° F.) and contact with the quench oil stream 18 in the contact zone 16. To produce a cooled vapor stream 20 having a temperature in the range of 25 ° C to 55 ° C (75 ° F to 130 ° F). According to certain embodiments, the olefin cracking reactor effluent stream 12 can have a temperature in the range of 150 ° C. to 210 ° C. (300 ° F. to 400 ° F.) Cooled by contact can produce a cooled vapor stream 20 having a temperature in the range of 35 ° C to 45 ° C (95 ° F to 115 ° F).

  According to certain embodiments, the cooled vapor stream 20 can then be separated into at least one light stream comprising a light olefin selected from ethylene, propylene, and combinations thereof.

  The quench oil stream 18 may desirably have a temperature in the range of 20 ° C. to 40 ° C. (70 ° F. to 100 ° F.) by contact with the olefin cracking reactor effluent stream 12 in the contact zone. Heated to form a heated quench oil stream 22 having a temperature in the range of 50 ° C to 75 ° C (120 ° F to 165 ° F). According to certain embodiments, the quench oil stream 18 can have a temperature in the range of 30 ° C to 35 ° C (85 ° F to 95 ° F). According to certain other embodiments, the quench oil stream 18 is heated by contact with the olefin cracking reactor effluent stream 12 in the range of 55 ° C to 65 ° C (130 ° F to 150 ° F). A heated quench oil stream 22 having a temperature of

  According to certain embodiments, the single contact region 16 can be a single packed layer containing an inert packing material. For example, various suitable filler materials known in the art such as rasching rings can be used in the packed bed. According to certain other embodiments, the single contact area 16 may include a tray assembly and / or a packed bed and tray, such as, for example, a Raschig ring followed by a disk and donut tray assembly. A combination with an assembly may also be used.

Prior to exiting the contact cooler 14, the cooled vapor stream 20 suitably passes through a mesh blanket or wire scrubber 28 where, for example, C ₆ + hydrocarbons (hydrocarbons having C ₆ or more carbon atoms). Droplets containing condensed hydrocarbons such as and / or aromatic compounds such as benzene, toluene, etc. are removed from the cooled vapor stream 20. Such condensed droplets are appropriately absorbed by the quench oil stream 18 and removed from the contact cooler 14 by the heated quench oil stream 22. Such a mesh blanket or wire scrubber 28 can be made from a tightly wrapped wire made of an inert and / or corrosion resistant material such as, for example, 316 stainless steel.

In addition to the condensed droplets, quench oil stream 18 is passed from olefin cracking reactor effluent stream 12 by physical contact between olefin cracking reactor effluent stream 12 and quench oil stream 18 in contact zone 16. For example, heavy components such as C ₆ + hydrocarbons (hydrocarbons having C ₆ or more carbon atoms) and / or aromatic compounds (eg benzene, toluene, etc.) can be absorbed or otherwise extracted. Such heavy components are removed from the contact area 16 by the heated quench oil stream 22.

The quench oil stream 18 advantageously comprises at least one C ₁₀ + hydrocarbon material (a hydrocarbon material having C ₁₀ or more carbon atoms). The use of such C ₁₀ + hydrocarbon material is preferred to minimize and / or otherwise prevent the quench oil material from evaporating into the cooled vapor stream 20. According to certain embodiments, the quench oil stream 18 advantageously comprises kerosene.

  The system (apparatus) 10 produces a cooled oil stream 34 and a heated coolant stream 46 by cooling the heated quench oil stream 22 by indirect heat exchange with the coolant stream 32. A first heat exchange region 30 may be further included. Suitably, the heated quench oil stream 22 is cooled by indirect heat exchange with the coolant stream 32 and has a temperature in the range of 20 ° C to 40 ° C (70 ° F to 100 ° F). Oil stream 34 can be produced. According to certain embodiments, the cooled oil stream 34 can have a temperature in the range of 35 ° C. to 40 ° C. (95 ° F. to 100 ° F.). At least a first portion 36 of the cooled oil stream 34 can be returned to the contact cooler 14 to provide the quench oil stream 18.

The second portion 38 of the cooled effluent stream 34 can be removed or discharged from the system 10 to produce a drag oil stream 40. Such a drag oil stream 40 is advantageously discharged or removed from the system 10 and absorbed or extracted from the olefin cracking reactor effluent stream 12 by the quench oil stream 18 in the contact zone 16. Reduce or eliminate the accumulation of heavy hydrocarbons such as C ₆ + hydrocarbons (hydrocarbons having C ₆ or more carbon atoms) and / or aromatic hydrocarbons (eg benzene, toluene, etc.) . By discharging such a drag oil stream 40, accumulation or condensation of heavy hydrocarbons in the system (device) 10 can also be prevented.

  According to certain embodiments, the heated quench oil stream 22 can be mixed with a heavy oil stream 42 to produce a composite heavy oil stream 44. Such a composite heavy oil stream 44 is then cooled by indirect heat exchange with the cooling medium stream 32 in the first heat exchange zone 30 to 20 ° C.-40 ° C. (70 ° F.-100 ° F.). A cooled oil stream 34 having a temperature in the range of

Advantageously, the heavy oil stream 42 comprises at least one C ₁₀ + hydrocarbon material (hydrocarbon material having C ₁₀ or more carbon atoms). The use of such C ₁₀ + hydrocarbon material is desirable to minimize and / or otherwise prevent the quench oil material from evaporating into the cooled vapor stream 20. According to certain embodiments, the heavy oil stream 42 advantageously comprises kerosene.

  According to certain embodiments, the cooling medium stream 32 may include a cooling water stream or an air cooling stream. The cooling medium stream 32 may suitably have a temperature of less than 35 ° C. (95 ° F.). In practice, the coolant stream 32 is heated by indirect heat exchange with the heated quench oil stream 22, or by indirect heat exchange with the composite heavy oil stream 44 according to certain embodiments. Heated to form a heated coolant stream 46.

  According to certain further embodiments, the system (apparatus) 10 may further include a pump 48 for recycling the heated quench oil stream 22, or certain embodiments (shown). The combined heavy oil stream 44 can be passed through the first heat exchange zone 30 to produce a cooled oil stream 34, quench oil stream 18, and drag oil stream 40.

According to certain further embodiments, a system for processing an olefin cracking reactor effluent stream, designated generally by reference numeral 110, as illustrated in FIG. Olefin cracking reactor in which an olefin rich feed stream 114 comprising C ₄ -C ₈ + olefins (olefins having C ₄ -C ₈ or more carbon atoms) is cracked to comprise at least one of ethylene and propylene An olefin cracking reactor 112 is provided that produces an effluent stream 116.

  According to certain embodiments, the olefin rich feed stream 114 is derived from a steam cracking effluent stream, a fluid catalytic cracking effluent stream, and an oxygenate to olefin conversion reactor effluent stream. May also include selected effluent streams.

  The system 110 includes a first olefin cracking reactor effluent stream 116 that is cooled by indirect heat exchange with an olefin rich feed stream 114 to produce a cooled effluent stream 120. One heat exchange region 118 is further included.

  According to certain embodiments, an olefin cracking reactor effluent stream 116 having a temperature in the range of 500 ° C. to 600 ° C. (930 ° F. to 1110 ° F.) is converted to olefins in the first heat exchange zone 118. Cooled by indirect heat exchange with the rich feed stream 114 to produce a cooled effluent stream 120 having a temperature in the range of 120 ° C to 210 ° C (250 ° F to 400 ° F). According to certain other embodiments, the olefin cracking reactor effluent stream 116 is cooled in the first heat exchange zone 118 to a temperature in the range of 150 ° C. to 210 ° C. (300 ° F. to 400 ° F.). To produce a cooled effluent stream 120 having

  The cooled effluent stream 120 is introduced into the contact cooler 122 below the single contact area 124. A quench oil stream 126 is introduced into the contact cooler 122 above the single contact region 124. The cooled effluent stream 120 is contacted in a countercurrent manner with the quench oil stream 126 in a single contact region 124 to produce a cooled steam stream 128 and a heated quench oil stream 130. According to certain embodiments, the material passing through the contact cooler 122 from the cooled effluent stream inlet 132 to the cooled vapor stream outlet 134 is less than 0.5 psi. Has pressure loss.

  According to certain embodiments, the single contact area 124 may be a single packed bed or tray assembly containing an inert packing material as described above.

  The heated quench oil stream 130 is then mixed with the heavy oil feed stream 136 to produce a composite heavy oil stream 138. According to certain embodiments, at least a first portion of the combined heavy oil stream 138 is returned to the contact cooler 122 to provide a quench oil stream 126.

  Advantageously, the combined heavy oil stream 138 is cooled by indirect heat exchange with the coolant stream 142 in the second heat exchange zone 140 to produce a cooled oil stream 144 and a heated coolant stream 146. To do. The first portion 148 of the cooled oil stream 144 is returned to the contact cooler 122 to supply a quench oil stream, and the second portion 150 of the cooled oil stream 144 is discharged to form a drag oil stream 152. To do.

  An embodiment as described above is an improved process for treating an olefin cracking reactor effluent stream to produce light olefins with increased relative yield, which desirably comprises conventional olefin cracking. Provides or results in a process that is more effective and / or more efficient than previously possible through the process and associated product separation process. More specifically, such embodiments can improve process economics through cooling of the olefin cracking reactor effluent stream by direct contact with the quench oil stream. For example, such treatment desirably can minimize system fouling due to heavy hydrocarbons and reduce pressure drop differences during the cooling and recovery process.

  The invention disclosed by way of example in the present specification can be appropriately practiced without any element, part, step, component or component not specifically disclosed in the present specification.

  In the foregoing detailed description, the invention has been described with reference to certain preferred embodiments thereof, and numerous details have been presented for the purposes of illustration, but the invention is susceptible to further embodiments. It will be apparent to those skilled in the art that the specific details described herein may be modified considerably without departing from the basic principles of the invention.

10 System (apparatus) for producing or producing light olefins
12 Olefin cracking reactor effluent stream 14 Contact cooler 16 Single contact zone 18 Quenched oil stream 20 Cooled steam stream 22 Heated quench oil stream 24 Olefin cracking reactor effluent stream inlet 26 Cooled Steam stream outlet 28 Mesh blanket or wire scrubber 30 First heat exchange zone 32 Coolant stream 34 Cooled oil stream 36 Cooled oil stream first part 38 Cooled oil stream second part 40 Drag oil stream 42 Heavy Oil Stream 44 Combined Heavy Oil Stream 46 Heated Coolant Stream 48 Pump 110 System for Treating the Olefin Cracking Reactor Effluent Stream
112 Olefin cracking reactor 114 Olefin rich feed stream 116 Olefin cracking reactor effluent stream 118 First heat exchange zone 120 Cooled effluent stream 122 Contact cooler 124 Single contact zone 126 Quenched oil stream 128 Cooled steam stream 130 Heated quench oil stream 132 Cooled effluent stream inlet 134 Cooled steam stream outlet 136 Heavy oil feed stream 138 Composite heavy oil stream 140 Second heat exchange zone 142 Coolant stream 144 Cooling Oil stream 146 Heated coolant stream 148 First part of cooled oil stream 150 Second part of cooled oil stream 152 Drag oil stream

Claims (9)

A method for cooling an olefin cracking reactor effluent stream (12, 116) comprising:
Producing an olefin cracking reactor effluent stream in the olefin cracking reactor, wherein the olefin cracking reactor effluent stream comprises C ₂ -C ₆ compounds;
Single contact cooler contact zone (14,122) wherein the olefin cracking reactor effluent stream of at least one _{C 10} + hydrocarbon quench oil stream containing _{(C 10} and higher hydrocarbons containing carbon atoms) in (18 ) to be contacted, the cooled vapor stream to generate the (26) to form a heated quench oil stream (22),
A pressure of 7 to 21 kPa is introduced to introduce the olefin cracking reactor effluent stream into the catalytic cooler to increase the relative yield of ethylene and / or propylene in the olefin cracking reactor effluent stream. And then
A method in which the pressure loss from the contact cooler inlet (24) to the contact cooler outlet (26) is less than 3.5 kPa. The method of claim 1, comprising:
Cooling the heated quench oil stream to produce a cooled oil stream (34) by indirect heat exchange with a cooling medium stream (32) in a first heat exchange zone (30) ;
Returning the first portion (36) of the cooled oil stream to the contact cooler to supply the quench oil stream; and
Further comprising the <br/> generating a drag oil stream (40) by discharging the cooled second portion of the oil flow (38). 3. The method of claim 2, further comprising mixing a heavy oil feed stream with the heated quench oil stream prior to cooling the heated quench oil stream. The method of claim 1, wherein the formed heated quench oil stream is cooled by indirect heat exchange with a cooling medium stream in a first heat exchange region to provide a cooled quench oil. A method further comprising generating a stream. 5. The method of claim 4, further comprising mixing a heavy oil feed stream with the heated quench oil stream prior to cooling the heated quench oil stream. 6. The method of claim 5, wherein a first portion of the cooled oil stream is returned to the contact cooler to supply the quench oil stream;
Discharging a second portion of the cooled oil stream to produce a drag oil stream;
A method further comprising: The method of claim 1, wherein the flow of the olefin cracking reactor effluent, containing at least one of ethylene and propylene. The method according to claim 1, _C 4 _~C 8 + olefins feed stream rich in olefins containing _(C 4 -C ₈ or more olefins having a carbon atom) (114) an olefin cracking reactor ( was introduced into 112), further comprising the generating a flow of the olefin cracking reactor effluent containing at least one of ethylene and propylene. An apparatus (110) for producing ethylene and propylene, comprising:
At least a portion of a feed stream (114) enriched in C ₄ + olefins (olefins having C ₄ or more carbon atoms) is passed to an olefin cracking reactor effluent stream (116) comprising at least one of ethylene and propylene. An olefin cracking reactor (112) for conversion;
At least a portion of the olefin cracking reactor effluent stream is quenched in a contact zone (124) comprising a quench oil stream (126 containing at least one C ₁₀ + hydrocarbon (a hydrocarbon containing C ₁₀ or more carbon atoms)). ) To produce a cooled vapor stream (128) and form a heated quench oil stream (130), the olefin cracking reactor effluent The single layer contact cooler having a pressure difference of less than 3.5 kPa from a flow inlet (132) to a cooled vapor flow outlet (134); and the heated quench oil stream is indirect with the cooling medium Heat exchanger (140), cooled by static heat exchange to form a cooled quench oil stream (144);
Including the device .

Images