Quenching system and method for using quenching system to cool pyrolysis gas from pyrolysis gas furnace

Abstract

The present invention relates to a quench system and a method for cooling pyrolysis gas from a pyrolysis gas furnace using different feedstocks, comprising a pyrolysis gas furnace (10), a primary quench exchanger or PQE (12) and a secondary quench exchanger connected in series. A transmission line exchanger or TLE arrangement and configuration for a cooling medium consisting of a gas mixture and steam or TLE-G / G (14) arrangement and configuration as a secondary quench exchanger. The TLE-G / G (14) is connected in series to the primary quench exchanger or PQE (12) by a gas transmission line (13). A feed line (15) conveying a cooling medium consisting of a gas mixture and steam is arranged at the TLE-G / G (14) at the lower part in front of the outlet header of the vertically oriented TLE-G / G. The TLE-G / G (14) is connected to the pyrolysis gas furnace (10) by means of a return line (16) for returning the cooling medium preheated in the TLE-G / G. The TLE-G / G (14) is equipped with a line (19) for the pyrolysis gas that has been cooled to a temperature in the range of 450 DEG C to 300 DEG C for further treatment. And a compensator (39) is arranged at the upper end of the TLE-G / G (14) behind the cracked gas inlet header.

Description

Technical Field

[0001] The invention relates to a quenching system and a method for using the quenching system to cool cracking gas from a cracking gas furnace. Background Art

[0002] There are different feedstocks that are further processed in cracking furnaces for operating ethylene furnaces, also called cracking gas furnaces or cracking furnaces. These feedstocks are heated to high temperatures in the cracking furnaces and then immediately cooled using a quench system, also referred to as QS.

[0003] Depending on the feedstock, a specially configured quench system or QS is required, because the physical properties of the feedstocks are different. A gas as feedstock can be cooled down to a greater extent than a liquid feedstock, for example, a gas can be cooled from 900°C to 150°C, and a liquid feedstock can be cooled from about 900°C to 350°C, because condensation of the gas only starts at a significantly lower temperature.

[0004] The quench system for liquid feed mode includes a primary heat exchanger (PQE) and a secondary heat exchanger (SQE) connected in series. In this case, the PQE and SQE are connected as a vaporizer and an evaporator, respectively, and also operate in this way.

[0005] EP 3 032 209 B1 may be mentioned as prior art. EP 3 032 209 B1 discloses a quench cooling system consisting of a primary quench cooler as a double-tube heat exchanger and a secondary quench cooler as a tube bundle heat exchanger (comprising at least one tube bundle). The tube bundle is surrounded by a jacket forming a jacket space, which is arranged between two tube sheets, which are arranged spaced apart from each other, between which the individual bundle tubes of the tube bundle are fixed in the tube sheets on both sides.

[0006] From US 8158840 B2 a method and apparatus for cracking liquid hydrocarbon residues with steam is known, wherein a steam / liquid separation device is used to treat the heated steam / liquid mixture and ensure that the steam stream has a reduced residue content. The method comprises indirect heat exchange of the liquid distillation residue with feed water or boiler feed water to provide liquid distillation residue and preheated feed water; transferring at least some of the preheated feed water to a steam drum; and recovering steam having a steam pressure of at least about 4100 kPa from the steam drum. Among other things, the apparatus comprises a liquid feed cracking furnace, a steam / liquid separation device and a primary heat exchanger and a secondary heat exchanger.

[0007] A heat exchanger for cooling cracked gas in an ethylene plant is known from EP 1 939 412 B1, wherein the heat exchanger tubes through which the cracked gas flows are inserted at their respective ends into a tube sheet and surrounded by a jacket, and at both end faces of the jacket, each end chamber is defined by a tube sheet section for supplying and discharging the cracked gas. Water flows as a cooling medium through the interior of the heat exchanger, which is surrounded by the jacket and divided into two subspaces, which are arranged one behind the other in the flow direction of the cracked gas and are provided with a respective supply and discharge pipe for the cooling medium by means of partitions which are at right angles to the heat exchanger tubes and through which the heat exchanger tubes pass.

[0008] Disadvantages of the arrangement of the quench system applied to cool the cracking gas from the cracking gas furnace It can be seen that the heat balance in the cracking gas cooling method has not yet reached a satisfactory level from the economic and environmental point of view. The cracking gas leaves the cracking gas furnace at a temperature range of 800°C to 900°C and a pressure of 0.5 bar to 2 bar or 0.05 bar to 0.2 bar. If this structure is to be implemented, the heat exchanger arranged directly behind the cracking gas furnace must be made of high-alloy steel. Compared with conventional technology, this configuration requires great efforts technically and is very expensive economically. It can be assumed that the cost increases by five to ten times. Therefore, it is absolutely necessary to precool the cracking gas from the cracking gas furnace in a conventional primary quench exchanger or a PQE cooled with water / steam.

[0009] In the case of quench coolers with water / steam cooling, the material temperature is significantly lower than in the case of quench coolers with gas cooling due to higher heat transfer, etc. The precooling of the cracked gas should have a temperature value of 700°C to 550°C, so that low-alloy to medium-alloy steels can be used in quench coolers to further cool the cracked gas, thus significantly reducing costs and protecting the environment. Summary of the invention

[0010] The object of the present invention is to provide a quenching system and a method for cooling cracking gas from a cracking gas furnace using different raw materials, which meets the high requirements on reliability and costs in terms of technical and environmental arrangements and operating modes and ensures simple possibilities for necessary repairs and maintenance.

[0011] The present object of the invention is substantially achieved by a quench system according to claim 1 and a method according to claim 6, wherein a transmission line exchanger for a cooling medium consisting of a gas mixture + steam (TLE-G / G for short) is arranged and configured as a secondary quench exchanger, the TLE-G / G being connected in series to a primary quench exchanger or PQE via a gas transmission line installed at the inlet end of the cracked gas in the TLE-G / G, the TLE-G / G being connected to a cracked gas furnace via a return line for preheating the cooling medium.

[0012] Furthermore, the TLE-G / G is equipped with a feed line for a cooling medium consisting of HC+steam. The outlet end of the TLE-G / G is arranged with a discharge line for the cooled down cracked gas.

[0013] Furthermore, the TLE-G / G is connected to the cracking gas furnace via a reflux line for preheating a cooling medium. Furthermore, a feed line for conveying a cooling medium consisting of a gas mixture and steam is arranged at the TLE-G / G in the lower part in front of the outlet header of the vertically oriented TLE-G / G.

[0014] The TLE-G / G is advantageously connected to the cracking gas furnace via a return line for returning a cooling medium consisting of hydrocarbon gas+steam or hydrocarbon+steam (HC+steam for short), which has been preheated in the TLE-G / G.

[0015] Furthermore, the TLE-G / G is equipped with a pipeline for conveying the cracked gas which has been cooled to a temperature in the range of 450°C to 300°C for further processing.

[0016] The compensator is preferably arranged at the upper end of the TLE-G / G behind the cracked gas inlet header. The gas inlet pipe for the feed line of the cooling medium is advantageously arranged at the jacket of the TLE-G / G. A plurality of baffles are preferably installed in the jacket space of the TLE-G / G, the number of which depends on the respective predefined load case and will be determined accordingly. In a counter-flow process around the baffles of the TLE-G / G, the cooling medium is alternately directed 180° around the outside of the bundle tubes.

[0017] Furthermore, the gas outlet pipe of the return line for preheating the cooling medium is preferably arranged at the jacket of the TLE-G / G at the upper end in front of the inlet header of the vertically oriented TLE-G / G. A section without tube bundles is advantageously arranged in the baffle area in the jacket space of the TLE-G / G.

[0018] The section through which free flow is possible is preferably sized to be 10% to 20% of the cross-sectional area of ​​the inner diameter of the jacket of the TLE-G / G.

[0019] The bundled tubes of the TLE-G / G are advantageously arranged in a triangular configuration for the flow of the cooling medium, wherein the side length of the triangle is 1.2 to 1.3 times the tube diameter of the bundled tube.

[0020] A compensator for compensating for the different thermal expansions between the bundle tubes and the jacket is advantageously mounted around the jacket of the TLE-G / G at the upper end behind the inlet header for the cracked gas from the TLE-G / G.

[0021] The cleaning pipe is preferably arranged in the jacket space region of the TLE-G / G near the tube sheet of the cracked gas outlet header of the TLE-G / G which is vertically oriented. In this case, in the jacket space region of the TLE-G / G, preferably two to four closable cleaning pipes are arranged, each of which has a diameter of 200 mm to 500 mm, wherein the cleaning pipe is installed at a distance of 100 mm to 200 mm from the lower tube sheet.

[0022] Depending on the predefined degree of contamination caused by coke deposits in the case of a horizontally oriented TLE-G / G, two to four cleaning pipes, each with a diameter of 200 mm to 500 mm, are arranged in the longitudinal direction in the lower region of the jacket space.

[0023] In the case of a method in which a quench system is used for cooling cracked gas from a cracked gas furnace using different raw materials, the quench system comprises a cracked gas furnace, a primary quench exchanger and a secondary quench exchanger connected in series, it is particularly advantageous when a transmission line exchanger or TLE-G / G for a cooling medium consisting of a gas mixture and steam is arranged and configured as a secondary quench exchanger. In this case, the TLE-G / G is connected in series to the primary quench exchanger or PQE via a gas transmission line.

[0024] At the TLE-G / G, a feed line for conveying a cooling medium consisting of a gas mixture and steam is advantageously arranged in the lower part in front of the inlet header of the vertically oriented TLE-G / G. The TLE-G / G is preferably connected to the cracking gas furnace via a return line for the return of the cooling medium preheated in the TLE-G / G. In addition, the TLE-G / G is equipped with a pipeline for cracking gas that has been cooled to 450° C. to 300° C. for further processing.

[0025] It is particularly advantageous to arrange a compensator at the upper end behind the cracked gas inlet header in the TLE-G / G.

[0026] Furthermore, it is advantageous if, at the jacket of the TLE-G / G, a gas inlet pipe for the cooling medium feed line is arranged in the lower part in front of the outlet header of the vertically oriented TLE-G / G.

[0027] It is further advantageous when a plurality of baffles are installed in the jacket space of the TLE-G / G, the number of which depends on and will be determined by the respective predefined load case. In this case, the cooling medium is advantageously directed alternately 180° around the outside of the bundle tubes in a counterflow method around the baffles of the TLE-G / G. The gas outlet pipe of the return line for preheating the cooling medium is particularly advantageously arranged at the jacket of the TLE-G / G at the upper end in front of the vertically oriented inlet header of the TLE-G / G.

[0028] Furthermore, sections without tube bundles are advantageously provided in the region of the baffles in the jacket space of the TLE-G / G.

[0029] The section through which free flow can be passed is preferably dimensioned to be 10% to 20% of the cross-sectional area of ​​the inner diameter of the jacket of the TLE-G / G. The bundled tubes of the TLE-G / G are advantageously arranged in a triangular configuration for the flow of the cooling medium, wherein the side length of the triangle is 1.2 to 1.3 times the tube diameter of the bundled tube.

[0030] A compensator for compensating for the different thermal expansions between the bundle tubes and the jacket is advantageously mounted around the jacket of the TLE-G / G at the upper end behind the inlet header for the cracked gas from the TLE-G / G.

[0031] Furthermore, the purge tube is preferably arranged in the vicinity of the tube sheet of the cracked gas outlet header of the TLE-G / G which is vertically oriented in the region of the jacket space of the TLE-G / G.

[0032] In the jacket space area of ​​the TLE-G / G, two to four closable cleaning pipes are preferably arranged, each of which has a diameter of 200 mm to 500 mm, wherein the cleaning pipes are installed at a distance of 100 mm to 200 mm from the lower tube sheet of the TLE-G / G outlet header.

[0033] It is also advantageous if, depending on the predefined degree of contamination caused by coke deposits in the case of a horizontally oriented TLE-G / G, two to four cleaning pipes are arranged in the longitudinal direction in the lower region of the jacket space, each with a diameter of 200 mm to 500 mm. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Further details and advantages of the invention are explained in detail based on the exemplary embodiments shown in the drawings. In the drawings:

[0035] Figure 1 A schematic arrangement of a quench system for cooling cracking gas from a cracking gas furnace according to the present invention is shown, the quench system being used for an air-cooled quench cooler;

[0036] Figure 2 shows a schematic arrangement of a quench cooler of a quench system according to the invention in a sectional view with detail AA, the quench cooler cooling on the basis of the countercurrent principle by gas conduction on the jacket side;

[0037] Figure 3 Shown according to Figure 2 A schematic arrangement of an enlarged detail AA of a bundle of tubes in a tube sheet for a quench cooler of a quench system according to the present invention;

[0038] Figure 4shows a schematic arrangement of a compensator for a quench cooler of a quench system according to the present invention;

[0039] Figure 5 shows a schematic arrangement of a purge pipe at a jacket of a vertically oriented quench cooler of a quench system according to the present invention; and

[0040] Figure 6 A schematic arrangement of a purge pipe at a jacket of a horizontally oriented quench cooler of a quench system according to the present invention is shown.

[0041] The reference numerals are as follows:

[0042] 10 Cracking gas furnace

[0043] 11 coils

[0044] 12 Primary heat exchanger or PQE precooler

[0045] 13 Gas transmission line

[0046] 14TLE-G / G as a quench cooler

[0047] 15HC+ steam feed line

[0048] 16HC+Steam Reflux Line

[0049] 17 Feed pipe

[0050] 18 Exhaust pipe

[0051] 19 pipeline

[0052] 30 Jacket Space

[0053] 31 Gas inlet pipe

[0054] 32 Gas outlet pipe

[0055] 33 Baffle

[0056] 34 paragraphs

[0057] 35 tubes

[0058] 36 bundle tube

[0059] 37 tube bundle / tube sheet

[0060] 38 Jacket

[0061] 39 compensator

[0062] 40 cleaning tube

[0063] 41 The arrows show the flow

[0064] 42 triangle configuration

[0065] 43 tube outer diameter

[0066] 44 tube sheet DETAILED DESCRIPTION

[0067] Figure 1 A schematic arrangement of a quench system for operating a cracking gas furnace 10 is shown, the quench system being used for a gas-cooled quench cooler. The quench cooler is arranged and configured as a transmission line exchanger or TLE for a cooling medium consisting of a gas mixture and steam, or TLE-G / G 14 for short, as a secondary quench exchanger. The TLE-G / G 14 is connected in series to a primary quench exchanger or PQE 12 and the cracking gas furnace 10.

[0068] Coil 11 is arranged in front of the cracking gas furnace 10 and leads to a schematically illustrated primary quench exchanger or PQE 12 as a precooler. In a conventional PQE 12 as a precooler, the cracking gas is precooled to about 700° C. to 550° C. or less. The PQE 12 is provided with a feed pipe 17 and an exhaust pipe 18. Cooling water is supplied via the feed pipe 17 and the water / steam mixture formed during precooling is conveyed via the exhaust pipe 18.

[0069] The known functions of the PQE 12 will not be discussed further below. The PQE 12, as a precooler, can only precool the high temperature cracked gas of 800° C. to 900° C. from the cracked gas furnace 10 to a temperature of about 700° C. to 550° C. In this regard, the material selection and related costs of the TLX-G / G 14 connected in series with the PQE 12 will be greatly simplified and reduced.

[0070] The TLE-G / G 14 is connected in series to the PQE 12 via a gas transfer line 13. The pre-cooled cracked gas from the PQE 12 is fed to the TLE-G / G on the tube side via the gas transfer line 13. The cracked gas is further cooled to a temperature of 450° C. to 300° C. in the TLE-G / G 14. The cracked gas is transferred via line 19 for further processing.

[0071] A feed line 15 is arranged at the lower end in front of the outlet header of the vertically oriented TLE-G / G 14 for a cooling medium consisting of a gas mixture and steam or hydrocarbon gas and steam or hydrocarbon and steam or HC+steam in short. A gas mixture consisting of HC+steam having a temperature of 200° C. to 290° C. is fed into the TLE-G / G 14 on the jacket side through the feed line 15 and flows through the TLX-G / G in a countercurrent method.

[0072] A return line 16 is arranged at the upper end in front of the inlet header of the TLE-G / G 14, which leads to the cracking gas furnace 10. The gas mixture consisting of HC+steam is preheated to 400° C. to 550° C. in the TLE-G / G 14 and then flows back to the cracking gas furnace 10. The preheated gas mixture consisting of HC+steam is further heated to 800° C. to 900° C. in the cracking gas furnace 10, where the gas mixture consisting of HC+steam is cracked. The cracking gas mixture or cracking gas is then fed again to the PQE 12 as a precooler. The method is repeated.

[0073] The precise function of the cracking gas furnace will not be discussed in further detail here, as its function is well known in the art.

[0074] Figure 2 A schematic arrangement with detail AA in a sectional view of a quench cooler of a quench system is shown, which cools on the basis of the countercurrent principle by gas conduction on the jacket side. The schematic TLE-G / G 14 shows a gas transmission line 13 arranged at the gas inlet and a pipeline 19 installed at the gas outlet. In the pipe 35 shown in the section AA, the precooled cracked gas or cracked effluent flows linearly from the gas transmission line 13 at the gas inlet through the TLE-G / G 14 to the pipeline 19 at the gas outlet and is cooled in the process.

[0075] In the jacket space 30 of the TLE-G / G 14, a gas mixture consisting of HC+steam is introduced through a gas inlet pipe 31 installed at the lower end in front of the vertically oriented TLE-G / G outlet header, and is directed in a flow method by a baffle 33 arranged in the TLE-G / G jacket space, alternately and repeatedly at 180° outside each bundle tube 36. The HC+steam mixture leaves the TLE-G / G 14 via a gas outlet pipe 32 installed at the upper end in front of the vertically oriented TLE-G / G inlet header.

[0076] The number of baffles 33 depends on the respective predefined load case and will be determined accordingly. Due to the repeated deflection of the HC+steam mixture, the pressure losses in the jacket space 30 are particularly high and should be minimized to achieve good efficiency of the quenching system. Therefore, the tube bundle / tube sheet 37 should have a particularly good configuration so that no bundled tubes 36 are located in the area of ​​the flow-through section 34. Keeping the section 34 free of bundled tubes 36 makes a significant contribution to reducing the pressure losses and is crucial for the method. The size of the section 34 through which free flow can flow is 10% to 20% of the cross-sectional area of ​​the jacket inner diameter and depends on the respective predefined load case.

[0077] Figure 3 Shown according to Figure 2Schematic arrangement of bundled tubes 36 of a tube bundle / tube sheet 37 with detail section AA. The arrangement of bundled tubes 36 must have a particularly good configuration when there is only minimal pressure loss, but high heat transfer and no stagnation should occur during the flow 41 of the HC+steam mixture, so as to achieve high cooling. The tube arrangement is preferably configured in a triangular configuration 42 to achieve high cooling, and the side length of the triangle should be 1.2 to 1.3 times the outer diameter 43 of the tube.

[0078] Figure 4 A schematic arrangement of a compensator for a TLE-G / G quench cooler of a quench system according to the invention is shown. Due to the relatively low heat transfer values, the material temperature of the TLE-G / G 14 is high and the temperature difference between the bundle tubes 36 and the jacket 38 can be very large. The mechanical stresses generated between the bundle tubes 36 and the jacket 38 due to the different thermal expansion should be compensated. Therefore, a compensator 39 should be arranged around the outer jacket space 30 at the upper end behind the inlet header of the vertically oriented TLE-G / G 14.

[0079] Figure 5 Shown according to Figure 4 Schematic arrangement of cleaning pipes at a TLE-G / G quench cooler of a quench system of a quenching system of a TLE-G / G. Due to the cooling medium consisting of HC+steam which is guided in the jacket space 30, it cannot be excluded that in the operating method deposits which need to be removed also form in the TLE-G / G 14. In the case of a vertically oriented TLE-G / G 14, closable cleaning pipes 40 are provided in the lower region near the outlet header of the jacket 38 for removing deposits. Depending on the predefined degree of contamination due to possible coke deposits, two to four cleaning pipes 40 should be provided, each with a diameter of 200 mm to 500 mm. The cleaning pipes should preferably be arranged close to the lower tube plate 44 of the TLE-G / G at a distance of about 100 mm to 200 mm.

[0080] Figure 6 A schematic arrangement of cleaning pipes at the quench cooler of a quench system TLE-G / G is shown. In the case of a horizontally oriented TLE-G / G 14, closable cleaning pipes 40 are provided longitudinally at the jacket 38 for removing deposits which are produced as a result of the cooling medium consisting of HC+vapor being guided in the jacket space 30 in the lower region of the jacket. Depending on the predefined degree of contamination caused by coke deposits which cannot be excluded, two to four cleaning pipes 40 are provided, each with a diameter of 200 mm to 500 mm.

[0081] The advantage when using a TLE-G / G quench cooler for the quench system is that the cracking gas is heated in the cracking gas furnace and precooled in the cracking process by the primary quench exchanger or PQE and then conducted by the TLE-G / G on the tube side and cooled further.

[0082] Unlike conventional quench coolers, a water / steam mixture is not used as the cooling medium on the jacket side in the TLE-G / G, but a gas mixture consisting of hydrocarbon gas and steam (abbreviated as HC+steam) or hydrocarbon and steam and steam. This mixture consisting of HC+steam is preheated in the TLE-G / G while it cools the cracking gas or cracking effluent from the cracking gas furnace, which is used to produce ethylene and then to produce plastics. The preheated mixture consisting of HC+steam is returned to the cracking gas furnace for further heating and cracking in the cracking gas furnace and then supplied to the TLE-G / G again via the PQE.

[0083] Due to the advantageous step or heat recovery, the energy required for heating the cracking gas furnace is reduced, which has a highly positive economic and environmental impact on the overall process in terms of costs and consumption.

[0084] A conventional PQE as a precooler should be used before a TLE-G / G in order to efficiently operate the cracking gas furnace not only during initial operation but also generally in the case of scheduling, implementation and post-repair or maintenance.

Claims

1. A quenching system for cooling cracking gas from a cracking gas furnace using different raw materials, comprising a cracking gas furnace (10), a primary quench exchanger or PQE (12) and a secondary quench exchanger connected in series, characterized in that: A transfer line exchanger or TLE for a cooling medium consisting of a gas mixture and steam is arranged and configured as a secondary quench exchanger or TLE-G / G (14), the TLE-G / G (14) being connected in series to a primary quench exchanger or PQE (12) via a gas transfer line (13), a feed line (15) for conveying a cooling medium consisting of a gas mixture and steam being arranged at the TLE-G / G (14) in the lower part in front of the outlet header of the vertically oriented TLE-G / G, the TLE-G / G (14) being connected to a cracking gas furnace (10) via a return line (16) for returning the cooling medium preheated in the TLE-G / G, the TLE-G / G (14) being equipped with a pipeline (19) for cracking gas cooled to a temperature in the range of 450°C to 300°C for further processing, a compensator (39) being arranged at the upper end of the TLE-G / G (14) behind the cracking gas inlet header.

2. The quenching system according to claim 1 is characterized in that: A gas inlet pipe (31) for a feed line (15) for a cooling medium is arranged at the jacket (38) of the TLE-G / G (14), a baffle (33) is installed in the jacket space (30) of the TLE-G / G (14), the cooling medium is alternately guided 180° around the outside of the bundle tubes (36) in a countercurrent method around the baffle (33) of the TLE-G / G (14), a gas outlet pipe (32) for a return line (16) for preheating the cooling medium is arranged at the jacket (38) of the TLE-G / G (14) at the upper end in front of the inlet header of the vertically oriented TLE-G / G, and a section (34) without a tube bundle (37) is provided in the baffle (33) area of ​​the jacket space (30) of the TLE-G / G (14).

3. The quenching system according to claim 2 is characterized in that: The section (34) through which free flow is possible is sized to be 10% to 20% of the cross-sectional area of ​​the inner diameter of the jacket (38) of the TLE-G / G (14).

4. The quenching system according to claim 2 is characterized in that: The bundled tubes (36) of the TLE-G / G (14) are arranged in a triangular configuration (42) for the flow (41) of a cooling medium, wherein the side length of the triangle is 1.2 to 1.3 times the tube diameter (43) of the bundled tube (36).

5. The quenching system according to claim 1 is characterized in that: A compensator (39) for compensating the different thermal expansion between the bundle tubes (36) and the jacket (38) is installed around the jacket (38) of the TLE-G / G (14) at the upper end behind the inlet header of the cracked gas from the TLE-G / G.

6. The quenching system according to claim 1, characterized in that: The cleaning tube (40) is arranged in the region of the jacket space (30) of the TLE-G / G (14) near the tube sheet (44) of the cracked gas outlet header of the vertically oriented TLE-G / G.

7. The quenching system according to claim 6, characterized in that: Two to four closable cleaning pipes (40) are arranged in the jacket space (30) area of ​​the TLE-G / G (14), each closable cleaning pipe (40) has a diameter of 200 mm to 500 mm, and the cleaning pipes (40) are installed at a position 100 mm to 200 mm away from the lower tube plate (44).

8. The quenching system according to claim 1 is characterized in that: Depending on the predefined degree of contamination caused by coke deposits in the case of a horizontally oriented TLE-G / G (14), two to four cleaning pipes (40) are arranged in the lower region of the jacket space (30) in the longitudinal direction, each cleaning pipe (40) having a diameter of 200 mm to 500 mm.

9. A method for cooling cracked gas from a cracked gas furnace using different raw materials, comprising a cracked gas furnace (10) connected in series according to patent claim 1, a primary quench exchanger or PQE (12) and a secondary quench exchanger, characterized in that A transfer line exchanger or TLE for a cooling medium consisting of a gas mixture and steam is arranged and configured as a secondary quench exchanger or TLE-G / G (14), the TLE-G / G (14) being connected in series to a primary quench exchanger or PQE (12) via a gas transfer line (13), a feed line (15) for conveying a cooling medium consisting of a gas mixture and steam being arranged at the TLE-G / G (14) in the lower part in front of the outlet header of the vertically oriented TLE-G / G, the TLE-G / G (14) being connected to a cracking gas furnace (10) via a return line (16) for returning the cooling medium preheated in the TLE-G / G, the TLE-G / G (14) being equipped with a pipeline (19) for cracking gas cooled to a temperature in the range of 450°C to 300°C for further processing, a compensator (39) being arranged at the upper end of the TLE-G / G (14) behind the cracking gas inlet header.

10. The method for a quenching system according to claim 9, characterized in that: A gas inlet pipe (31) for a feed line (15) for a cooling medium is arranged at the jacket (38) of the TLE-G / G (14), a plurality of baffles (33) are installed in the jacket space (30) of the TLE-G / G (14), the number of baffles (33) depending on and to be determined by the respective predefined load conditions, the cooling medium is alternately guided 180° around the outside of the bundle tubes (36) in a countercurrent method around the baffles (33) of the TLE-G / G (14), a gas outlet pipe (32) for a return line (16) for preheating the cooling medium is arranged at the jacket (38) of the TLE-G / G (14) at the upper end in front of the inlet header of the vertically oriented TLE-G / G, and a section (34) without a tube bundle (37) is provided in the region of the baffles (33) in the jacket space (30) of the TLE-G / G (14).

11. The method for a quenching system according to claim 10, characterized in that: The section (34) through which free flow is possible is sized to be 10% to 20% of the cross-sectional area of ​​the inner diameter of the jacket (38) of the TLE-G / G (14).

12. The method for a quenching system according to claim 10, characterized in that: The bundled tubes (36) of the TLE-G / G (14) are arranged in a triangular configuration (42) for the flow (41) of a cooling medium, wherein the side length of the triangle is 1.2 to 1.3 times the tube diameter (43) of the bundled tube (36).

13. The method for a quenching system according to claim 9, characterized in that: A compensator (39) for compensating for the different thermal stresses between the bundle tubes (36) and the jacket (38) is installed around the jacket (38) of the TLE-G / G (14) at the upper end behind the inlet header of the cracked gas from the TLE-G / G.

14. The method for a quenching system according to claim 9, characterized in that: The cleaning tube (40) is arranged in the region of the jacket space (30) of the TLE-G / G (14) near the tube sheet (44) of the cracked gas outlet header of the vertically oriented TLE-G / G.

15. The method for a quenching system according to claim 14, characterized in that: Two to four closable cleaning pipes (40) are arranged in the jacket space (30) area of ​​the TLE-G / G (14), each closable cleaning pipe (40) has a diameter of 200 mm to 500 mm, and the cleaning pipes (40) are installed at a position 100 mm to 200 mm away from the lower tube plate (44) of the TLE-G / G outlet header.

16. The method for a quenching system according to claim 9, characterized in that: Depending on the predefined degree of contamination caused by coke deposits in the case of a horizontally oriented TLE-G / G (14), two to four cleaning pipes (40) are arranged in the lower region of the jacket space (30) in the longitudinal direction, each cleaning pipe (40) having a diameter of 200 mm to 500 mm.

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