A reaction device for preparing oxalamide from oxalate

Abstract

The present invention relates to the technical field of chemical equipment, and in particular to a reaction device for preparing oxalamide from oxalic acid esters. The device includes a feed zone, a reaction zone, a sedimentation zone and a solid-liquid separation zone in sequence according to the fluid flow direction; the device also includes an inert gas balance port, a first material inlet, a second material inlet and a circulating liquid inlet respectively connected to the cavity of the feed zone; the solid-liquid separation zone includes a solid-phase material collection zone and a liquid-phase material collection zone; an overflow baffle is provided between the solid-phase material collection zone and the liquid-phase material collection zone, and the solid-phase material collection zone is connected to the sedimentation zone cavity; the device also includes a first crude product outlet connected to the solid-phase material collection zone cavity, a circulating liquid outlet and a second crude product outlet connected to the liquid-phase material collection zone cavity; and also includes a heat recovery device connected to the reaction zone. By using the device of the present invention, the conversion rate of dimethyl oxalate is high and the selectivity of the product oxalamide is high.

Description

Technical Field

[0001] The invention relates to the technical field of chemical equipment, in particular to a reaction device for preparing oxalamide from oxalate. Background Art

[0002] Oxamide, also known as oxalic acid diamide, has a CAS registration number of 471-46-5. It has a molecular weight of 88.07 and a nitrogen content of 31.8%. It is slightly soluble in water, insoluble in ethanol and ether, non-hygroscopic, stable in nature, easy to store, and can be decomposed into ammonia and carbonic acid. It is a good and efficient slow-release fertilizer. Compared with my country's traditional quick-acting nitrogen fertilizers (such as urea), oxamide is not easy to volatilize, insoluble in water, not easy to lose, has a high nitrogen utilization rate, and can reduce economic losses and water pollution.

[0003] With the industrial development of preparing dimethyl oxalate from synthesis gas in my country, the cost of dimethyl oxalate has dropped significantly. The preparation of oxalamide from dimethyl oxalate and ammonia is suitable for large-scale industrial production and has a good industrial prospect. The reaction has the characteristics of simple process, raw materials and products involving gas, solid and liquid phases, high conversion rate of raw material dimethyl oxalate, high selectivity of product oxalamide, and the product is insoluble in water and alcohol, easy to separate, easy to obtain high-purity products, and large reaction exothermic heat.

[0004] The prior art uses a kettle reactor to synthesize oxalamide, which is inefficient. Another prior art uses a continuous gas phase reaction and a fluidized bed reactor to produce oxalamide, but oxalate needs to be gasified, resulting in high reaction temperature and energy consumption, and the gas phase reaction product oxalamide is prone to clogging pipelines. Summary of the invention

[0005] In view of the above-mentioned shortcomings of the prior art, the object of the present invention is to provide a reaction device for preparing oxalamide from oxalate, so as to solve the problems in the prior art.

[0006] To achieve the above-mentioned object and other related objects, the present invention provides a reaction device for preparing oxalamide from oxalate, wherein the device comprises a feed zone, a reaction zone, a sedimentation zone and a solid-liquid separation zone in sequence according to the fluid flow direction; the device also comprises an inert gas balance port, a first material inlet, a second material inlet and a circulating liquid inlet respectively connected to the cavity of the feed zone; a vertically extending reactor tube is provided in the reaction zone, and the reactor tube extends from the feed zone to the sedimentation zone; the feed zone also comprises a first liquid distributor, the first material inlet is fluidically connected to the first liquid distributor, and each discharge port of the first liquid distributor extends into each reactor tube respectively. tubes, and they correspond one to one; the reaction equipment also includes a second liquid distributor, the second liquid distributor is fluidically connected to the second material inlet, the second liquid distributor is distributed on the periphery of each reactor tube, and is used to separate the feed area and the reaction area; the reaction equipment also includes a third liquid distributor, the circulating liquid inlet is connected to the third liquid distributor cavity, and each discharge port of the third liquid distributor is evenly distributed above the reactor tube; the solid-liquid separation zone includes a solid-phase material collection zone and a liquid-phase material collection zone; an overflow baffle is provided between the solid-phase material collection zone and the liquid-phase material collection zone, and the solid-phase material collection zone is connected to the sedimentation zone cavity.

[0007] In some embodiments of the present invention, the equipment also includes a first crude product outlet connected to the solid material collection area cavity, a circulating liquid outlet and a second crude product outlet connected to the liquid material collection area cavity; and also includes a heat recovery device connected to the reaction area.

[0008] In some embodiments of the present invention, the second liquid distributor is selected from an overflow liquid distributor.

[0009] In some embodiments of the present invention, the third liquid distributor is selected from a trough-type liquid distributor or a sieve plate-type liquid distributor.

[0010] In some embodiments of the present invention, the height of the second material inlet is higher than the height of the second liquid distributor; the height of the second material inlet is lower than the height of the liquid inlet of the reactor tube array.

[0011] In some embodiments of the present invention, the height of the circulating liquid inlet is higher than that of the first material inlet.

[0012] In some embodiments of the present invention, the device further comprises a crude product collection plate for preventing the reacted material from entering the liquid phase material collection zone, and the crude product collection plate is arranged between the sedimentation zone and the liquid phase material collection zone.

[0013] In some embodiments of the present invention, the heat recovery device includes a heat exchange medium inlet and a heat exchange medium outlet, which are respectively connected to the shell side of the reaction zone; the height of the heat exchange medium inlet is lower than the heat exchange medium outlet.

[0014] In some embodiments of the present invention, the height of the circulating liquid outlet is higher than that of the second raw product outlet.

[0015] In some embodiments of the present invention, the sedimentation zone is provided with baffles and / or spiral plates according to the fluid flow direction.

[0016] In some embodiments of the present invention, the angle between the working surface of the baffle or spiral plate and the radial direction of the reaction zone is 30 to 60 degrees.

[0017] In some embodiments of the present invention, the device is provided with a feed zone, a reaction zone, a sedimentation zone and a solid-liquid separation zone in order from top to bottom.

[0018] Beneficial effects of the present invention:

[0019] In the reaction equipment for preparing oxalamide from oxalate esters, raw material dimethyl oxalate and ammonia fully react in a reaction zone, and a large amount of circulating liquid is used for flushing, so that a solid product is in a slurry state and will not block the reactor; the circulating liquid is mainly an ammonia-containing methanol solution, so that the reaction zone has excessive ammonia, the conversion rate of dimethyl oxalate is high, and the product oxalamide has high selectivity; the product is simply separated at the bottom of the reactor; and a heat recovery device recovers a large amount of reaction heat, saving energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of a reaction device for preparing oxalamide from oxalate of the present invention.

[0021] Component numbers in the figure:

[0022] 1 Feeding area

[0023] 2 Reaction zone

[0024] 3 Settlement area

[0025] 4 Solid-liquid separation area

[0026] 41 Solid phase material collection area

[0027] 42 Liquid material collection area

[0028] 5 Inert gas balance port

[0029] 6 First Material Import

[0030] 7 Second material import

[0031] 8 Circulating fluid inlet

[0032] 9 Heat recovery device

[0033] 91 Heat exchange medium inlet

[0034] 92 Heat exchange medium outlet

[0035] 10 First crude product export

[0036] 11 Circulating fluid outlet

[0037] 12 Second crude product export

[0038] 13 Reactor tubes

[0039] 14. First liquid distributor

[0040] 15. Second liquid distributor

[0041] 16 Third liquid distributor

[0042] 17 Tube Sheet

[0043] 18 Crude product collection plate

[0044] 19 Overflow baffle

[0045] 20 spiral plate DETAILED DESCRIPTION

[0046] In the description of the present invention, it should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of the present specification are only used to match the contents disclosed in the specification for people familiar with the technology to understand and read, and are not used to limit the limiting conditions that the present invention can be implemented, so they have no technical substantive significance. Any modification of the structure, change of the proportion relationship or adjustment of the size, without affecting the effects that the present invention can produce and the purposes that can be achieved, should still fall within the scope of the technical content disclosed by the present invention. At the same time, the directions or positional relationships indicated by the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. are based on the directions or positional relationships shown in the drawings, which are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0047] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0048] Furthermore, in the description of the present invention, unless otherwise specified, “plurality” means two or more.

[0049] like Figure 1 As shown, the present invention relates to a reaction device for preparing oxalamide from oxalate, wherein the device comprises a feed zone 1, a reaction zone 2, a sedimentation zone 3 and a solid-liquid separation zone 4 in sequence according to the fluid flow direction; the device also comprises an inert gas balance port 5, a first material inlet 6, a second material inlet 7 and a circulating liquid inlet 8 respectively connected to the cavity of the feed zone 1; a vertically extending reactor tube 13 is provided in the reaction zone 2, and the reactor tube 13 extends from the feed zone 1 to the sedimentation zone 3; the feed zone 1 also comprises a first liquid distributor 14, the first material inlet 6 is fluidically connected to the first liquid distributor 14, and each discharge port of the first liquid distributor 14 extends into each reactor tube 13 respectively, and corresponds to each other one by one; The reaction equipment also includes a second liquid distributor 15, which is fluidically connected to the second material inlet 7. The second liquid distributor 15 is distributed on the periphery of each reactor tube 13 and is used to separate the feed zone 1 and the reaction zone 2; the feed zone 1 also includes a third liquid distributor 16, the circulating liquid inlet 8 is connected to the cavity of the third liquid distributor 16, and the various discharge ports of the third liquid distributor 16 are evenly distributed above the reactor tubes; the solid-liquid separation zone 4 includes a solid-phase material collection zone 41 and a liquid-phase material collection zone 42; an overflow baffle 19 is provided between the solid-phase material collection zone 41 and the liquid-phase material collection zone 42, and the solid-phase material collection zone 41 is connected to the cavity of the sedimentation zone 3.

[0050] In a specific embodiment of the reaction equipment for preparing oxalamide from oxalate of the present invention, an inert gas such as nitrogen is introduced into the feed zone 1 from the inert gas balance port 5, dimethyl oxalate liquid is introduced into the reactor tube 13 of the reaction zone 2 from the first material inlet 6 through the first liquid distributor 14, and liquid ammonia is introduced into the feed zone 1 from the second material inlet 7 through the second liquid distributor 15. The circulating liquid is introduced into the feed zone 1 from the circulating liquid inlet 8 through the third liquid distributor 16. The reaction material and the circulating liquid are introduced into the reaction tube 13 of the reaction zone 2 to react and generate oxalamide, and the reaction is a liquid phase reaction, and the reaction equation is as follows: CH3OOCCOOCH3+2NH3=H2NCOCONH2+2CH3OH. The pressure is balanced by an inert gas such as nitrogen, so that the entire reaction equipment is safe. The raw material dimethyl oxalate and ammonia react fully in the reaction zone 2. A large amount of circulating liquid is flushed, so that the solid product is in a slurry state and will not block the reaction equipment. The circulating liquid is mainly an ammonia-containing methanol solution, so that there is an excess of ammonia in the reaction zone 2, the conversion rate of dimethyl oxalate is high, and the selectivity of the product oxalamide is high; the product is settled in the sedimentation zone and then simply separated in the solid-liquid separation zone 4.

[0051] In the reaction device for preparing oxalamide from oxalate provided by the present invention, the device further includes a first crude product outlet 10 connected to the cavity of the solid phase material collection area 41, a circulating liquid outlet 11 connected to the cavity of the liquid phase material collection area 42, and a second crude product outlet 12; and also includes a heat recovery device 9 connected to the reaction zone 2. The slurry crude product collected by the solid phase material collection area 41 flows out through the first crude product outlet 10; some crude products will further settle through the liquid phase material collection area 42 and flow out through the second crude product outlet 12; the liquid phase material collected by the liquid phase material collection area 42, such as product methanol and circulating liquid, will flow out through the circulating liquid outlet 11. Among them, the heat recovery device 9 recovers a large amount of reaction heat, saving energy consumption.

[0052] In the reaction equipment for preparing oxalamide from oxalate provided by the present invention, the number of the reactor tubes 13 can be, for example, 20 to 2000.

[0053] In the reaction equipment for preparing oxalamide from oxalate provided by the present invention, in one embodiment, the first liquid distributor 14 is selected from a spray liquid distributor. In a specific embodiment, the spray liquid distributor includes a spray pipe horizontally arranged in the feed zone 1 and a plurality of nozzles arranged on the lower side of the spray pipe, and each nozzle extends into the reactor tube. When in use, the dimethyl oxalate solution enters the spray liquid distributor through the first material inlet 6, and after pressurization, it is injected into the reactor tube 13 through the plurality of nozzles of the spray liquid distributor, and each nozzle extends into each reactor tube 13. Under normal circumstances, the nozzle extends below the reaction liquid level of the reactor tube 13 to prevent blockage. The pressure of the dimethyl oxalate solution is 0.05 to 1.0 MPa higher than the reaction pressure of the reaction zone 2. More preferably, it is higher than 0.1 to 0.5 MPa. In a specific embodiment, the pressure of the dimethyl oxalate solution is 0.2 MPa higher than the reaction pressure.

[0054] In the reaction equipment for preparing oxalamide from oxalate provided by the present invention, in a specific embodiment, the second liquid distributor 15 is selected from an overflow liquid distributor. The overflow liquid distributor can be, for example, a baffle provided in the reaction zone and the feed zone, and the diameter of the baffle is equal to the inner diameter of the feed zone 1. The baffle is provided with a plurality of through holes for accommodating reactor tubes. The diameter of the through hole is substantially equal to the outer diameter of the reactor tube. The overflow liquid distributor can be used to separate the feed zone 1 and the reaction zone 2. The height of the overflow liquid distributor is lower than the height of the second material inlet 7.

[0055] In the reaction equipment for preparing oxalamide from oxalate provided by the present invention, the height of the second material inlet 7 is lower than the height of the liquid inlet of the reactor tube 13. The height of the second liquid distributor 15 is lower than the height of the liquid inlet of the reactor tube 13. Liquid ammonia is added to the reactor tube 13 by overflow. In this way, ammonia can be excessive in the reaction equipment and evenly added to each reactor tube.

[0056] In the reaction equipment for preparing oxalamide from oxalate provided by the present invention, the circulating liquid enters the cavity of the feed zone 1 through the third liquid distributor 16. The third liquid distributor 16 is selected from a trough-type liquid distributor or a sieve plate-type liquid distributor. In this way, the circulating liquid can be evenly distributed and the ammonia in the gas phase can be sprayed and absorbed. Among them, the self-trough-type liquid distributor is arranged in the feed zone 1, and a plurality of slots are provided as liquid outlets in the direction of the reaction zone 2. Relative to the array arrangement of the reactor tubes, each liquid outlet is respectively oriented to each reactor tube array, so that the liquid flows into the reactor tube 13 in the direction of the reaction zone 2. The circulating liquid that does not directly enter the reactor tube 13 can also overflow to the second liquid distributor 15, and further overflow into the reactor tube 13, and finally the circulating liquid is discharged through the circulating liquid outlet 11. The aperture of the sieve plate liquid distributor is 3-20 mm, the hole spacing is 15-60 mm, the opening rate is 30-70%, and the diameter is consistent with the diameter of the feed zone 1. Normally, the circulating liquid is pumped through a filter to the interior of a reaction device for preparing oxalamide from oxalate.

[0057] In the reaction equipment for preparing oxalamide from oxalate provided by the present invention, the height of the circulating liquid inlet 8 is higher than the height of the first material inlet 6, which can achieve better spray absorption.

[0058] In the reaction equipment for preparing oxalamide from oxalate provided by the present invention, the heat recovery device 9 includes a heat exchange medium inlet 91 and a heat exchange medium outlet 92, and the heat exchange medium inlet 91 and the heat exchange medium outlet 92 are respectively connected to the shell side of the reaction zone 2. The shell side here refers to the part outside the reactor tube. Usually, the heat exchange medium of the reaction zone 2 is located outside the reactor tube 13, and the heat exchange medium can be water, heat transfer oil, etc. The height of the heat exchange medium inlet 91 is lower than the heat exchange medium outlet 92, and a large amount of reaction heat can be recovered.

[0059] In the reaction device for preparing oxalamide from oxalate provided by the present invention, the device further comprises a crude product collection plate 18 for preventing the material entering the sedimentation zone after the reaction from directly entering the liquid phase material collection zone 42, and the crude product collection plate 18 is arranged between the sedimentation zone 3 and the liquid phase material collection zone 42. Usually, the material in the sedimentation zone 3 will enter the solid phase material collection zone 41 through the crude product collection plate 18, and further pass through the overflow baffle 19 for solid-liquid separation.

[0060] In the reaction equipment for preparing oxalamide from oxalate provided by the present invention, the shape of the sedimentation zone 3 is cylindrical, and the sedimentation zone 3 facilitates the slow descent of materials to the solid-liquid separation zone 4. In one embodiment, the sedimentation zone 3 can be an empty tube. In other embodiments, the sedimentation zone 3 is provided with a baffle and / or a spiral plate 20 in the direction of fluid flow. The angle between the working surface of the baffle or spiral plate 20 and the radial direction of the reaction zone 2 is 30 to 60 degrees. In some embodiments, the angle between the working surface of the baffle or spiral plate 20 and the radial direction of the reaction zone 2 can be 30 to 40 degrees, 40 to 50 degrees, or 50 to 60 degrees. In a specific implementation, the angle between the working surface of the baffle or spiral plate 20 and the radial direction of the reaction zone 2 is 45 degrees. Such a design can achieve a mixing effect, ensure complete reaction, and the product goes down smoothly. Among them, the spiral plate includes a column extending from the sedimentation zone in the direction of fluid flow, a spiral surface is provided along the circumference of the column, and the edge of the spiral surface matches the inner wall of the sedimentation zone. The distance between the baffles is 0.8-1.5d (d: diameter of the sedimentation zone).

[0061] In the reaction equipment for preparing oxalamide from oxalate provided by the present invention, the equipment is provided with a feed zone 1, a reaction zone 2, a sedimentation zone 3 and a solid-liquid separation zone 4 in order from top to bottom. The equipment is a cylinder. The diameter of the cylinder in the area where the feed zone 1 and the reaction zone 2 are located is 300-6000 mm. The diameter of the cylinder in the area where the sedimentation zone 3 and the solid-liquid separation zone 4 are located is 200-4000 mm. The height of the feed zone 1 is 500-1000 mm. The height of the reaction zone 2 is 1000-6000 mm. The height of the sedimentation zone 3 is 1000-6000 mm. The height of the solid-liquid separation zone 4 is 500-3000 mm. The reaction temperature of the reaction zone 2 is 40-200° C., and the reaction pressure is 0.1-5.0 MPa. The reaction time is 1-20 min.

[0062] In the reaction equipment for preparing oxalamide from oxalate provided by the present invention, the tube sheet 17 is arranged at the bottom of the reaction zone 2, and a plurality of through holes matching the reactor tubes are provided on the tube sheet 17, which is used to separate the reaction zone 2 and the settling zone 3. The tube sheet 17 is necessary for the heat recovery device 9 and is used to isolate the reactants from the heat exchange medium.

[0063] In summary, the raw material dimethyl oxalate reacts fully with ammonia in the reaction zone 2, and a large amount of circulating liquid is used for flushing, so that the solid product is in a slurry state and will not clog the reactor; the circulating liquid is mainly an ammonia-containing methanol solution, so that the reaction zone 2 has an excess of ammonia, the dimethyl oxalate conversion rate is high, the dimethyl oxalate conversion rate is greater than 99.5%, and the product oxamide selectivity is high, the oxamide selectivity is greater than 99.5%; the product is simply separated at the bottom of the reactor; the heat recovery device 9 recovers a large amount of reaction heat, saving energy consumption.

[0064] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A reaction device for preparing oxalamide from dimethyl oxalate and ammonia, characterized in that: The device comprises a feed zone (1), a reaction zone (2), a sedimentation zone (3) and a solid-liquid separation zone (4) in order of fluid flow direction; the device also comprises an inert gas balance port (5), a first material inlet (6), a second material inlet (7) and a circulating liquid inlet (8) respectively connected to the cavity of the feed zone (1); a vertically extending reactor tube (13) is provided in the reaction zone (2), and the reactor tube (13) extends from the feed zone (1) to the sedimentation zone (3); the feed zone (1) also comprises a first liquid distributor (14), the first material inlet (6) and the first liquid distributor (14) are fluidically connected, and each outlet of the first liquid distributor (14) extends into each reactor tube (13) and corresponds to each other; the reaction device also comprises a second liquid distributor (14); The second liquid distributor (15) is fluidically connected to the second material inlet (7), the second liquid distributor (15) is distributed on the periphery of each reactor tube (13), and is used to separate the feed zone (1) and the reaction zone (2); the feed zone (1) also includes a third liquid distributor (16), the circulating liquid inlet (8) is connected to the cavity of the third liquid distributor (16), and each discharge port of the third liquid distributor (16) is evenly distributed above the reactor tube (13); the solid-liquid separation zone (4) includes a solid-phase material collection zone (41) and a liquid-phase material collection zone (42); an overflow baffle (19) is provided between the solid-phase material collection zone (41) and the liquid-phase material collection zone (42), and the solid-phase material collection zone (41) is connected to the cavity of the sedimentation zone (3); The second liquid distributor (15) is selected from an overflow liquid distributor, the height of the second material inlet (7) is higher than the height of the second liquid distributor (15); the height of the second material inlet (7) is lower than the height of the liquid inlet of the reactor tube array (13), and the height of the circulating liquid inlet (8) is higher than the first material inlet (6).

2. The reaction equipment for preparing oxalamide from dimethyl oxalate and ammonia as claimed in claim 1, characterized in that: The device also includes a first crude product outlet (10) connected to the cavity of the solid phase material collection zone (41), a circulating liquid outlet (11) connected to the cavity of the liquid phase material collection zone (42), and a second crude product outlet (12); and also includes a heat recovery device (9) connected to the reaction zone (2).

3. The reaction equipment for preparing oxalamide from dimethyl oxalate and ammonia as claimed in claim 1, characterized in that: The third liquid distributor (16) is selected from a trough type liquid distributor or a sieve plate type liquid distributor.

4. The reaction equipment for preparing oxalamide from dimethyl oxalate and ammonia as claimed in claim 1, characterized in that: The device also includes a crude product collection plate (18) for preventing the reacted material from entering the liquid phase material collection zone (42); the crude product collection plate (18) is arranged between the sedimentation zone (3) and the liquid phase material collection zone (42).

5. The reaction equipment for preparing oxalamide from dimethyl oxalate and ammonia as claimed in claim 2, characterized in that: The heat recovery device (9) comprises a heat exchange medium inlet (91) and a heat exchange medium outlet (92), wherein the heat exchange medium inlet (91) and the heat exchange medium outlet (92) are respectively connected to the shell side of the reaction zone (2); the height of the heat exchange medium inlet (91) is lower than that of the heat exchange medium outlet (92).

6. The reaction equipment for preparing oxalamide from dimethyl oxalate and ammonia as claimed in claim 2, characterized in that: The height of the circulating liquid outlet (11) is higher than the second crude product outlet (12).

7. The reaction equipment for preparing oxalamide from dimethyl oxalate and ammonia as claimed in claim 1, characterized in that: The sedimentation zone (3) is provided with baffles or spiral plates (20) according to the flow direction of the fluid.

8. The reaction equipment for preparing oxalamide from dimethyl oxalate and ammonia as claimed in claim 7, characterized in that: The angle between the working surface of the baffle or spiral plate (20) and the radial direction of the reaction zone (2) is 30 to 60 degrees.

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