ITRM980613A1 - COMPLEX FOR THE TREATMENT OF GAS VEHICLES LOADED WITH PRODUCT VAPORS - Google Patents

Description

DESCRIPTION

accompanying a patent application for an invention entitled: "Complex for cooling vehicle gases laden with product vapors".

A complex for cooling a hot gaseous vehicle, coming out of a reactor and loaded with product vapors, is particularly known in the production of phthalic anhydride (AF).

In order to be able to recover the AF from the gaseous carrier at a temperature of about 370 ° C, it must be cooled to 170 ° C before being introduced into an AF desublimator. For this purpose, the gaseous carrier has hitherto first been conveyed into a preliminary gas coolant which is arranged horizontally and connected via a tubular pipe to a main reactor. In the preliminary gas coolant, the carrier gas is cooled in a first step to a temperature of about 300 ° C. To improve the efficiency and quality of the product, the gaseous carrier is subsequently conveyed through a tubular duct to a secondary reactor, crossing it again in a vertical direction from bottom to top. This leads to a heating of the gaseous carrier to about 320 ° C. The gaseous carrier charged with AF, which leaves the secondary reactor, is then conveyed through another tubular duct to a coolant, in which the gaseous carrier is cooled to 170 ° C. From the gas refrigerant the gaseous carrier is fed to desublimators, in which the AF is recovered from the gaseous carrier. The desublimators are also connected with the gas refrigerant through tubular ducts. As a rule, in consideration of the loading and melting operations, four desublimators are provided.

The known plant structure is necessary to take into account the different conditions regarding the permissible inflow rates of the preliminary gas coolant, the secondary reactor as well as the gas coolant. However, this entails not only a considerable need for surface area but also a considerable need for space for the arrangement of the gas coolant and the secondary reactor between the main reactor, where the transformation of the material used in the AF takes place and the desublimators, in which AF is recovered. Therefore no significant investment expenditure is required. Since both the main reactor and the secondary reactor have to be made with a vertical axis, it is therefore necessary to provide long tubular conductors with multiple elbows between the main reactor and the preliminary gas coolant as well as between the preliminary gas coolant and the secondary reactor. These tubular ducts also have a considerable volume of gaseous carrier. Consequently, corresponding supports, supports and compensators are required. In addition, the main reactor as well as the secondary reactor must be supported by appropriate steel structures, as they are located at a great distance above the floor, since the charged gas carrier must be removed from the reactor downwards and then conveyed. horizontally into the preliminary gas coolant and the carrier gas leaving the preliminary gas coolant is to be introduced back into the secondary reactor from below.

It is also necessary to feed the gaseous vehicle, exiting upwards from the secondary reactor, again through suitably long and elbowed tubular ducts, to the gas coolant and from the latter to the desublimators. All these devices, aggregates and appliances must be supported by corresponding steel structures. This leads to a further increase in investment expenditure.

In particular due to the tubular ducts which connect the preliminary gas coolant with the secondary reactor and the secondary reactor with the gas coolant, as well as the necessary passage elements therein, pressure losses cannot be avoided. However, the greater loss of pressure requires a greater power of the compressors for the passage of the gaseous vehicle, which consequently increases the operating costs. Normally, the gaseous vehicle loaded with product vapors, such as AF, passes through the explosive zone. This entails an increased risk of an explosion with the volumes enclosed in various tubular devices and ducts, i.e. in the known case greater precautions against explosion are necessary, since due to the extended position of the various devices and the tubular conductors that connecting, a large volume of gas is necessarily enclosed in a continuous manner. Starting from the state of the art, the invention has set itself the task of realizing a complex for the cooling of a hot gaseous vehicle, loaded into a product vapor reactor, which has a compact structure so that the expenditure can be significantly reduced. investment and operation, increasing operational safety. The solution of this task consists according to the invention in the characteristics indicated in claim 1.

The core of the invention is to structurally unite the preliminary gas coolant in the form of a heat exchange unit, the secondary reactor and the gas coolant, likewise in the form of at least one heat exchange unit, in a shell. This casing preferably has a vertical extension axis with a supply of the hot carrier gas in the lower region and with an exhaust of the cooled carrier gas in the upper region. In this way it will advantageously be taken into account that the charged gaseous carrier leaves the main reactor from below and is usually introduced into the upper zone of the desublimators. Thanks to this, only two relatively short tubular ducts are now required between the main reactor and the casing, respectively between the casing and the desublimators. Therefore it becomes only necessary to support the casing and the two tubular ducts by means of corresponding steel structures. The resulting investment expenditure is reduced by 30 to 50% in comparison with the state of the art. The other advantage is that the need for surfaces and space is significantly reduced. Since the tubular ducts and also the devices to ensure the gas velocities between the separate aggregates are lacking, the result is a considerable reduction in pressure losses and therefore a lower compressor power, for which the operating costs are equally lowered. . Operational safety is increased, as the volume of gas enclosed as a whole is significantly reduced. The risk of explosions is considerably lowered.

In this regard it is important that the first heat exchange unit is adjustable and that the catalyst forming the component of the secondary reactor is fed uniformly. The uniform supply is obtained due to the fact that the catalyst is placed at a distance from the first heat exchange unit, the first heat exchange unit causing, thanks to the pressure loss that takes place in it, at the same time a uniformity of the vehicle gas over the entire cross section of the enclosure.

An optimum operating temperature for the secondary reactor is achieved in that the temperature of the fluid heat carrier is regulated in the first heat exchange unit.

The fluid heat carrier, passing through the heat exchange units, can be oil, water or water vapor. The choice of the fluid heat carrier used depends on the consumer requesting the heat.

In order to ensure the temperature necessary for the operation of the desublimators, according to the characteristics of claim 2, it may be advantageous to arrange downstream of the second heat exchange unit a third heat exchange unit, crossed by a fluid heat carrier, in the direction of gaseous carrier flow.

A particularly advantageous embodiment of the invention consists of the features of claim 3. According to them, a cylindrical casing with a vertical axis is used.

This embodiment advantageously makes it possible to produce and assemble the casing in situ, even in a technically less developed ground, while only the most delicate heat exchange installations as well as the catalyst have to be supplied from a country having a technical level. superior .

In this embodiment, the hot gaseous carrier flows centrally from below into the envelope and first urges the first heat exchange unit. A settling space for the carrier gas is provided between this heat exchange unit and the secondary reactor, located remotely above it, with the integrated catalyst. The height of the settling space corresponds approximately to the height of the secondary reactor. The gaseous vehicle exiting vertically upwards from the catalyst is then displaced laterally through appropriate deviation means, from the vertical axis of the casing and deflected horizontally to the upper end of the casing, where it urges the second unit in a horizontal direction. heat exchange and possibly also a third heat exchange unit. The exhaust port of the cooled gaseous carrier is located laterally to the casing and is directed radially. In this way, only an extremely short tubular connection between the housing and the desublimators becomes necessary.

According to the characteristics of claim 4, it is convenient for the first heat exchange unit to comprise a tubular bundle extending radially inwards from the peripheral circumference of the casing, the inlet and outlet ports of which face radially. In particular, four tubular bundles offset from each other with their principal axes of 90 ° can be radially extended into the casing. These tubular bundles can be replaceable due to their significantly shorter radial length compared to the diameter of the casing. The tubular bundles can have tubes having a U-shaped configuration. However, straight tubes, extending parallel to each other, with distribution and deviation terminal chambers are also possible.

With regard to the second heat exchange unit and possibly also the third heat exchange unit, these are conveniently formed of tubular bundles, which extend according to claim 5 from the upper side of the housing downwards into a gas channel. extending transversely into the envelope. This arrangement also makes it possible to replace the tube bundle. Its inlet and outlet openings face vertically upwards from the upper side of the casing. However, the inlet and outlet openings can also be arranged laterally to the casing. In this embodiment, the bundles of tubes can also have tubes having a U-shaped configuration or in a relative parallel position with distribution and diversion terminal chambers.

Another variant within the previously illustrated embodiment is provided according to the characteristics of claim 6. According to them, at least the third heat exchange unit is equipped with heating pipes, the heating pipes extend with a longitudinal sector with a gas channel, formed in the upper region of the housing and with the remaining longitudinal sector in an air channel, preferably extending above the housing. However, the air channel can be arranged above the enclosure. It is also possible to equip the second heat exchange unit with heating pipes.

With this embodiment there is the particular advantage that the quantity of air necessary for the operation of the main reactor is heated directly in the same process, in which a cooling of the gaseous carrier flowing with a sufficient temperature difference takes place.

Another advantageous embodiment of the invention consists of the characteristics of claim 7. According to these characteristics, the first heat exchange unit, the catalyst and each subsequent heat exchange unit are superimposed on each other. These areas are stressed in order of succession by the gaseous carrier flowing exclusively in the vertical direction. In this case, the casing has a rectangular horizontal cross section with arched curved inlet and outlet hoods. The inlet hood can be chamfered on a front side to apply the tubular duct here to reduce the expenditure associated with the latter. The vehicle gas exhaust ports are preferably located in the center of the exhaust hood. Since, due to the overlap of the first heat exchange unit, the catalyst as a component of the secondary reactor and the second heat exchange unit, the transverse and longitudinal extension of the casing is relatively large, the casing can be made in a subdivided manner , conveniently approximately in the central area, to facilitate transport and assembly.

The second heat exchange unit and possibly also a subsequent third heat exchange unit require a high speed of the gaseous carrier, higher than that which it presents in the catalyst. Accordingly, according to claim 8 it is provided that the casing has a transition section between the catalyst and the second heat exchange unit which is adapted to increase the flow rate of the gaseous carrier. Here it can be a sector of the casing, of trapezoidal shape in the vertical transverse plane. The heat exchange units are preferably formed, according to claim 9, of tube bundles with a U-shaped guide, which is welded into the shell. Instead of the tube bundle with a U-shaped guide, it is also possible to use tube bundles with tubes extending parallel to each other and with distribution or diversion terminal chambers. However, in order to reduce the waste of pipes, all the inlet and outlet ports of the tube phases are located on the same side of the casing.

The invention will be described in more detail below with reference to embodiments illustrated in the drawings, in which:

Figure 1 shows a schematic view of a plant for the recovery of phthalic anhydride (AF); Figure 2 is an enlarged view of the area II of Figure 1 according to a first embodiment;

Figure 3 shows a horizontal cross section through the illustration of Figure 2, along the line III-III;

Figure 4 is a horizontal cross section through the illustration of Figure 2, along the line IV-IV;

figure 5 shows the upper sector of figure 2 according to another embodiment;

figure 6 represents the view of the zone II of figure 1 according to another embodiment and figure 7 shows a side view of the illustration of figure 6 according to arrow VII.

The reference number 1 in Figure 1 indicates a main reactor, which is stressed from above with a gaseous carrier TG. The gaseous carrier TG passes through the main reactor 1. In the main reactor 1 the transformation of a material used into AF takes place. This involves heating the gaseous carrier TG to about 370 ° C.

From the main reactor 1, the gaseous carrier TG, charged with AF, is conveyed to a complex 2 for its cooling. It through a tubular duct 3, indicated only schematically. The gaseous carrier TG, loaded and cooled in the complex 2 to about 170 ° C, exits in the upper zone from the complex 2 and is then conveyed, through a tubular duct 4, equally indicated only schematically, to four desublimators 5, in which the AF is recovered from the gaseous carrier TG. The desublimators 5 are first stressed with the gaseous carrier TG and cooled. Phthalic anhydride (AF) sublimates and is deposited on the pipes. By the subsequent removal by melting the phthalic anhydride can be recovered from the tubes. Reference number 6 indicates a tubular duct which carries away the exhaust gas.

A first embodiment of the assembly 2 for cooling the gaseous carrier TG is shown more closely in Figures 2 to 4.

The assembly 2 comprises a cylindrical casing 8, resting on uprights 7, with an arc-shaped inlet hood 9 in the lower area and with an upper flat lid 10. The tubular duct 3 is connected to the center of the introduction hood 9 for the introduction of the gasso vehicle TG. The gaseous carrier TG is first distributed in the introduction hood 9 and then urges a first heat exchange unit 11, arranged in the lower area of the casing 8. This heat exchange unit 11 is composed as a whole of four bundles 12 with a U-shaped tube guide. The tube bundles 12 extend radially inward from the peripheral circumference of the casing 8. They are offset from each other by 90 °. Each tube bundle 12 has an inlet union 13 and an outlet union 14, through which a fluid heat carrier can be introduced into the tube bundle 12 and discharged therefrom. The tube bundles 12 are replacably supported. The areas between the tube bundles 12 and the casing 8 are closed with sheets 15.

At a distance above the heat exchange unit 11 extends a sieve plane 16, on which rests a catalyst 17 as a component of a secondary reactor 18. At a distance above the secondary reactor 18, in the upper area of the The enclosure 8 is formed a transversely extending gas channel 19. The gas channel 19 is delimited at the top by the cover 10 of the casing 8 and at the bottom by an insertion plate 20. The insertion plate 20 can be shaped as a collector and drain for leakage fluids.

In the gas channel 19 a second heat exchange unit 21 and a third heat exchange unit 22 penetrate from the cover 10 into a series arrangement. Their inlet 23, 24 and outlet 25, 26 openings face vertically in top starting from the lid 10. The second and third heat exchange units 21, 22 are also formed, in a manner not shown more closely, from tube bundles with a U-shaped tube guide. The tube bundles are stressed with a fluid heat carrier.

At the radially external end of the gas channel 19 there is an outlet union 27 of the gaseous carrier TG, fixed in the wall of the casing 8. As can be seen from Figure 2, the hot gaseous carrier TG first passes through the first exchange unit of heat 11 in the vertical direction, then quietens behind the first heat exchange unit 11 and then passes through the catalyst 17, in which the gaseous carrier TG is once again heated. In the area of the inlet hood 9, of the first heat exchange unit 11, of the settling space 28 and of the catalyst 17, the flow direction STR of the gaseous carrier TG is substantially vertical.

At the rear of the catalyst 17, the gaseous carrier TG is radially deflected by means of deflection 29 from the longitudinal axis of the casing 8 and then guided in the form of an arc into the gas channel 19, in which it first urges the second exchange unit horizontally. of heat 21 and therefore the third heat exchange unit 22. Through the radial discharge openings 27 the gaseous carrier TG leaves the casing 8 at a temperature of about 170 ° C.

In the case of the embodiment of Figure 5, the third heat exchange unit 31 comprises heating pipes 30. The heating pipes 30 penetrate with a first longitudinal sector 32 into the gas channel 19 in the upper region of the casing 8 and with the residual longitudinal sector 33 in an air channel 34, arranged above the casing 8. For the rest, the embodiment of Figure 5 corresponds to that of Figures 2 to 4, so that a further description is superfluous.

In the embodiment illustrated in Figures 6 and 7, a substantially rectangular casing 35 is used as part of the assembly 2 for cooling the gaseous carrier TG.

The casing 35 has at the lower end an arc-shaped inlet hood 36, which is beveled from the front side and equipped with an inlet port 37 for the gaseous vehicle TG. Above the inlet hood 36 is a first heat exchange unit 38 in the form of tube bundles, not shown more closely, with a U-shaped tube guide. The tube bundles are welded into the shell 35. The inlet unions of the heat exchange unit 38 are indicated with the reference number 39, while the discharge unions are indicated with the number 40.

Above the first heat exchange unit 38 a sieve plane 41 extends at a distance, transversely through the casing 35, on which rests a catalyst 42 as a component of a secondary reactor 43.

Above the secondary reactor 43, the casing 35 has a transition sector 44, having a trapezoidal vertical cross section according to Figure 7. Above the transition sector 44 is a second heat exchange unit 45 consisting of tube bundles 46 with a U-shaped tube guide, which extend transversely through the casing 35. The inlet ports 47 and those 48 of this heat exchange unit 45 are arranged on the same front side 49 as the casing 35, on which there are also the inlet ports 34 and the outlet ports 40 of the first heat exchange unit 38, arranged in the direction flow rate STR of the gaseous carrier TG in front of the catalyst 42.

Above the second heat exchange unit 45 there is a third heat exchange unit 50. It also consists of tube bundles 51 with a U-shaped tube guide. third heat exchange unit 50 are likewise arranged on the front side 49 of the casing 35.

Above the third heat exchange unit 50, the casing 35 is closed by an arc-shaped exhaust hood 54. An outlet port 55 for the gaseous carrier TG is located centrally to the exhaust hood 54.

It should also be noted that a lockable Mann hole 56 is provided in front of the transition sector 44 as well as in front of the outlet hood 54.

The gaseous carrier TG entering the envelope 35 through the inlet ports 37 at approximately 370 ° C, is first distributed in the inlet hood 36 and then urges the first heat exchange unit 36 vertically from below.

Here the gaseous carrier TG is cooled to approximately 300 ° C. Subsequently, the gaseous carrier TG passes through the catalyst 42 in the vertical flow direction STR and is heated there again to about 320 ° C. In the transition sector 44 the gaseous carrier TG undergoes the necessary speed increase to be then cooled in the subsequent heat exchange units 45 and 50 to 170 ° C. With this temperature, the gaseous carrier TG leaves the casing 35 through the exhaust ports 55 and is then fed, according to Figure 1, to the desublimators 5.

Claims (9)

CLAIMS 1. A complex for the cooling of a hot gaseous vehicle (TG), coming out of a reactor (1) and loaded with product vapors, which has a first exchange unit of adjustable heat (11, 38), traversed by a fluid heat carrier, a catalyst (17, 42), arranged at a distance from it and forming a component of a secondary reactor (18, 43) and a second heat exchange unit (21, 45) crossed by a fluid heat carrier, which are stressed in succession by the gaseous carrier (TG), the gaseous carrier (TG) entering at one end into the enclosure (8, 35) and leaving the enclosure (8, 35) at the other end. 2. Assembly according to claim 1, characterized in that downstream of the second heat exchange unit (21, 45) a third heat exchange unit is arranged in the direction of flow (STR) of the gaseous carrier (TG) (22, 31, 50) traversed by a fluid heat carrier. Complex according to claim 1 or 2, characterized in that the first heat exchange unit (11) as well as the catalyst (17) are superimposed in a cylindrical casing (8) and are stressed by the gaseous carrier (TG) flowing in the vertical direction, while each subsequent heat exchange unit (21, 22, 31) in the flow direction (STR) of the carrier gas (TG), is stressed by the carrier gas (TG) flowing in the horizontal direction. Assembly according to one of claims 1 to 3, characterized in that the first heat exchange unit (11) has a tube bundle (12) extending radially inward from the peripheral circumference of the casing (8), whose inlet unions (13) and outlet unions (14) face radially. Assembly according to one of claims 1 to 4, characterized in that at least the second heat exchange unit (21), stressed by the gaseous carrier (TG) in the horizontal direction, is formed by tube bundles extending from the upper side (10 ) of the casing (8) at the bottom into a gas channel (19) extending transversely into the casing (8), the inlet ports (23) and outlet ports (5) of which face upwards. Assembly according to one of claims 1 to 5, characterized in that at least the third heat exchange unit (31) comprises heat pipes (30) which penetrate with a longitudinal sector (32) into a gas channel ( 19), extending transversely into the casing (8) and with the remaining longitudinal sector (33) in an air channel (34), provided parallel to the gas channel (19). 7. Assembly according to claim 1 or 2, characterized in that the first heat exchange unit (38), the catalyst (42) and each subsequent heat exchange unit (45, 50) are superimposed in an enclosure (35) of rectangular cross section and are stressed by the carrier gas (TG) flowing in the vertical direction. 8. Assembly according to claim 7, characterized in that the casing (35) has a transition sector (44) between the catalyst (42) and the second heat exchange unit (45) which increases the flow rate of the carrier gas (TG). Assembly according to one of claims 1, 2, 7 or 8, characterized in that the heat exchange units (38, 45, 50) comprise tube bundles (46, 51), which are provided with inlet ports (39 , 47, 52) and discharge ports (40, 48, 53) for the fluid heat carrier, arranged on one side (49) of the casing (35).