A high-pressure methylammonium condenser

Abstract

The present invention discloses a high-pressure methylammonium condenser, comprising: a shell and a tube bundle and internal components within the shell; the shell is provided with a methylammonium liquid inlet and a CO2 gas inlet at the bottom, and a reaction liquid outlet and a gas outlet at the top; the heat exchange tube bundle is a U-shaped tube structure, through which a heat-conducting medium removes the heat generated by the hydrolysis of methylammonium; the internal components include a high-efficiency tower tray; and the downcomer is supported by the high-efficiency tower tray. The present invention solves the problems of existing methylammonium condensers, such as low heat transfer coefficient, high tube head stress, large layout space, and difficulty in manufacturing and transportation. The high-pressure methylammonium condenser has a small heat exchange area, low tube head stress, is easy to arrange, easy to manufacture and scale up, and convenient to transport.

Description

Technical Field

[0001] The invention belongs to the field of chemical equipment, and in particular relates to a novel high-pressure methylammonium condenser. Background Art

[0002] The high-pressure loop of the urea plant mainly includes three links: synthesis, separation and heat recovery condensation. It is the core of the entire urea plant. Among them, the high-pressure condenser is the key equipment to complete heat recovery condensation. Different urea processes have different structural forms.

[0003] At present, the main urea processes at home and abroad include Stamicarbon CO2 stripping process, Snam ammonia stripping process, Toyo ACES21 process, China Wuhuan high-efficiency synthesis, low-energy urea process, etc. Among them, the most competitive process in the market is CO2 stripping 2000 +TM The main processes are pool condenser process and China Wuhuan high-efficiency synthesis and low-energy consumption urea process.

[0004] The key equipment for completing reaction heat recovery in Stamicarbon's CO2 gas stripping process is the pool condenser. This equipment is a horizontal U-tube heat exchanger with the process medium flowing through the shell side and the steam-water mixture flowing through the tube side. It has the following problems: 1. The horizontal layout occupies a large area, which is not conducive to layout; 2. A large number of distributors are required at the bottom of the shell-side tube bundle, and the tube bundle support structure is complex, requiring high manufacturing precision; 3. Due to height restrictions, the vertical axis of the equipment needs to be placed in a horizontal state, and temporary supports and pre-tightening mechanisms are required to fix the tube bundle.

[0005] The key equipment for completing heat recovery and condensation in China Wuhuan's high-efficiency synthetic and low-energy urea process is the high-pressure methylammonium condenser. This equipment is a vertical fixed tube sheet heat exchanger, with the process medium flowing through the tube side and the steam-water mixture flowing through the shell side. It has the following problems: 1. The process medium flows through the tube side, and low-pressure steam is produced as a by-product in the shell side. Natural circulation is adopted, and the heat transfer coefficient is small. The required heat exchange area of the full condensation reactor is large, and the equipment diameter is large. When the device is scaled up, the equipment diameter increases, and the equipment material is super thick, which brings challenges to the raw material supply and processing and manufacturing of the equipment; 2. For fixed tube sheet heat exchangers, the thermal expansion difference between the tube and shell sides is different, and expansion joints need to be installed. The stress on the tube head is large, which increases the risk of stress corrosion cracking and failure of the heat exchange tube; 3. The tube bundle contains a long central tube, and the length of the central tube often exceeds the manufacturer's supply capacity. Therefore, the central tube has a splicing weld, and the splicing manufacturing requirements are high. Summary of the Invention

[0006] The purpose of the present invention is to solve the above technical problems and provide a high-pressure methylammonium condenser with small heat exchange area, small tube head stress, easy layout, easy manufacturing, large-scale and convenient transportation.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions: A novel high-pressure methylammonium condenser comprises: a shell and a heat exchange tube bundle and internal parts inside the shell;

[0008] The bottom of the shell is provided with a methylammonium liquid inlet and a CO2 gas inlet, and the upper part is provided with a reaction liquid outlet and a gas outlet; the heat exchange tube bundle is a U-shaped tube structure, and the heat transfer medium carries away the heat generated by the hydrolysis of methylammonium through the heat exchange tube bundle;

[0009] The internal components include a high-efficiency tower tray; the downcomer is supported by the high-efficiency tower tray;

[0010] Methylammonium liquid enters the shell side of the high-pressure methylammonium condenser from the methylammonium liquid inlet, and the raw gas enters the shell side of the high-pressure methylammonium condenser from the CO2 gas inlet; the methylammonium liquid is deflected in the high-efficiency tower tray, and the gas is collected in the skirt plate of the high-efficiency tower tray and flows upward along the gas phase channel of the tower tray, reacting between the high-efficiency tower trays to generate methylammonium, and part of the methylammonium is hydrolyzed to generate urea. The urea methylammonium solution generated by the final reaction flows out from the reaction liquid outlet, and the unreacted gas flows out from the gas outlet.

[0011] Furthermore, the high-efficiency tray is distributed in a baffled manner in the shell side of the high-pressure methylammonium condenser, the gap between the high-efficiency tray and the shell is a liquid phase channel, and a gas phase channel is provided on the high-efficiency tray.

[0012] Furthermore, the gas phase channel is a distribution hole with a diameter of 3-4 mm opened in the central area supported by the baffle and the non-support area.

[0013] Furthermore, the high-efficiency tower plate is provided with a skirt plate and an anti-short-circuit baffle; the skirt plate is used to collect gas and make the gas flow along the gas phase channel; the anti-short-circuit baffle is used to prevent the shell side fluid flow from short-circuiting, and the fluid flows out directly without passing through the surface of the shell side heat exchange tube.

[0014] Furthermore, a pipe box is provided on the top of the high-pressure methylammonium condenser, and a tube-side inlet and an outlet are provided on the pipe box. The heat-conducting medium steam condensate is forced to circulate through a steam condensate pump and enters from the tube-side inlet, then enters the tube bundle, taking away the heat generated by the hydrolysis of methylammonium on the shell side. The steam condensate is heated to generate steam, and the steam flows out from the outlet.

[0015] Furthermore, a partition plate is provided in the pipe box.

[0016] Furthermore, the internals also include a downcomer, which is arranged in the high-efficiency tower tray and is used to circulate unreacted materials. The downcomer is supported by the high-efficiency tower tray and is a thin-walled non-pressure-bearing structure with a vortex breaker on the top.

[0017] Furthermore, the internal parts also include a methylammonium liquid inlet distributor and a gas inlet distributor; the methylammonium liquid inlet is provided with a methylammonium liquid inlet distributor, and the CO2 gas inlet is provided with a gas inlet distributor, so that the methylammonium liquid and CO2 are evenly distributed and then enter the shell side of the high-pressure methylammonium condenser.

[0018] Furthermore, the methylammonium liquid inlet distributor and the gas inlet distributor are distribution plates with distribution holes or inner extension pipe structures with distribution holes.

[0019] Furthermore, the reactor is a vertical reactor, which is supported by a skirt support, an ear support, or a rigid ring support.

[0020] The novel high-pressure methylammonium condenser of the present invention has the following advantages:

[0021] (1) Small heat exchange area. The process medium of the new high-pressure methylammonium condenser flows through the shell side, which is equipped with high-efficiency trays. The liquid phase fluid is deflected between the trays, and the gas phase fluid is collected in the high-efficiency tray skirt and flows upward along the distribution holes of the tray, increasing the flow turbulence, improving the heat transfer coefficient and reaction rate, and reducing the required heat exchange area.

[0022] (2) Low tube head stress. The new high-pressure ammonium methylate condenser tube bundle adopts a U-shaped tube structure, which allows the tube bundle to expand freely. This avoids the thermal stress problem caused by the inconsistent thermal expansion of the shell and tube sides of the traditional high-pressure ammonium methylate condenser. The equipment does not need to be equipped with an expansion joint, reducing the risk of stress corrosion on the tube head.

[0023] (3) Easy to arrange. The new high-pressure methylammonium condenser is a vertical reactor that uses skirt support, ear support, or rigid ring support. Compared with the pool condenser, it occupies a smaller area and is easier to arrange. The condensation section and reaction section of the new high-pressure methylammonium condenser are both on the shell side, which shortens the reactor length and requires less space for arrangement, making it easier to arrange.

[0024] (4) Easy to manufacture and scale up. The new high-pressure ammonium methylate condenser has a simple structure. Compared with the pool condenser, it does not have a complex distributor and tube bundle support structure. Compared with the traditional high-pressure ammonium methylate condenser with a thick-walled pressure-bearing central tube structure, it uses a thin-walled non-pressure-bearing downcomer structure, which is easy to manufacture. The number of heat exchange tubes required is small, the tube sheet diameter is small, and the calculated thickness of the tube sheet is small, which makes it easy to scale up the device.

[0025] (5) Convenient transportation. The high-efficiency tower tray on the shell side of the new high-pressure ammonium methylate condenser also serves as a support plate for the heat exchange tubes, which supports the heat exchange tubes. Compared with the pool-type condenser, it does not require temporary support and pre-tightening mechanisms during transportation. Compared with the traditional high-pressure ammonium methylate condenser, it is shorter in length, has a smaller turning radius during transportation, is lighter in weight, and is convenient to transport. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a structural schematic diagram of a new type of high-pressure methylammonium condenser of the present invention.

[0027] Figure 2 This is a schematic diagram of welding the heat exchange tubes and inner holes of the tube sheet of a new high-pressure methylammonium condenser of the present invention.

[0028] Among them, 1-skirt, 2-methylammonium liquid inlet, 3-methylammonium liquid inlet distributor, 4-shell side lower head, 5-manhole, 6-lower cylinder, 7-downcomer, 8-heat exchange tube bundle, 9-high-efficiency tower plate, 10-shell side upper head, 11-tube sheet, 12-gas outlet, 13-steam condensate inlet, 14-pass partition, 15 tube box, 16-steam outlet, 17-tube sheet welding layer, 18-reaction liquid outlet, 19-upper single-layer cylinder, 20-layer plate, 21-leak detection hole, 22-inner cylinder, 23-lining, 24-CO2 gas inlet distributor, 25-CO2 gas inlet. DETAILED DESCRIPTION

[0029] In order to enable those skilled in the art to better understand the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of this application.

[0030] It should be noted that the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or are inherent to these processes, methods, products or apparatuses.

[0031] See also Figure 1 and Figure 2 A new type of high-pressure methylammonium condenser includes a shell and a heat exchange tube bundle and internal parts inside the shell.

[0032] The shell comprises a pipe box 15, a shell-side upper head 10, an upper single-layer cylinder 19, a layer plate 20, an inner cylinder 22, a liner 23, a lower cylinder 6, and a shell-side lower head 4. The shell is also provided with a leak detection hole 21. The shell-side cylinder (including the lower cylinder 6, the upper single-layer cylinder 19, and the cylinder between them) can be a single-layer or multi-layer structure. The multi-layer cylinder structure composed of layer plates, inner cylinder, and liner is economical, safe, and reliable. The liner is in direct contact with the medium and its material has excellent corrosion resistance. The inner cylinder and layer plates must be designed to be strong enough to withstand the pressure of the equipment.

[0033] The shell is arranged vertically and supported by a skirt 1.

[0034] The bottom of the shell side lower head 4 is provided with a carbamate liquid inlet 2 and a CO2 gas inlet 25. The carbamate liquid inlet 2 is provided with a carbamate liquid inlet distributor 3, and the CO2 gas inlet 25 is provided with a CO2 gas inlet distributor 24.

[0035] A reaction liquid outlet 18 is provided on the lower cylinder 6, and a gas outlet 12 is provided on the shell side upper head.

[0036] The pipe box 15 is provided with a steam condensate inlet 13 and a steam outlet 16. The lower cylinder 6 has a single-layer structure and a multi-layer structure, is provided with a leak detection system, and is provided with a manhole 5.

[0037] The heat exchange tube bundle 8 is a U-shaped tube structure, connected to the tube sheet 11 by internal hole welding. The high-efficiency tray 9 is equipped with distribution holes, skirts, and anti-short-circuiting baffles, and supports the heat exchange tube bundle 8. The tube box 15 is equipped with a partition plate 14.

[0038] The high-efficiency trays are distributed in a baffled pattern within the shell side of the high-pressure methylammonium condenser. The gap between the high-efficiency trays and the shell is the liquid phase channel, and the high-efficiency trays are provided with gas phase channels. The gas phase channels are distributed holes with a diameter of 3-4 mm opened in the central area of the baffle support and the non-support area.

[0039] The internal parts also include a downcomer, which is arranged in the high-efficiency tower tray and supported by the high-efficiency tower tray. It is a thin-walled non-pressure-bearing structure with a vortex breaker on the top.

[0040] See also Figure 1 Methylammonium liquid from the high-pressure scrubber enters through methylammonium liquid inlet 2, is evenly distributed through methylammonium liquid inlet distributor 3, and then enters the shell side of the high-pressure methylammonium condenser. Gases (CO2, NH3, and H2O) from the stripping tower and urea synthesis tower enter through CO2 gas inlet 25, are evenly distributed through CO2 gas inlet distributor 24, and then enter the shell side of the high-pressure methylammonium condenser. The methylammonium liquid is deflected within the high-efficiency trays. The gases are collected within the high-efficiency tray skirts and flow upward along the tray distribution holes. There, they react between the high-efficiency trays to produce methylammonium, and some of the methylammonium is hydrolyzed to produce urea. The resulting urea methylammonium solution exits through reaction liquid outlet 18 and enters the urea synthesis tower for further reaction. Unreacted gases exit through gas outlet 12 and enter the high-pressure scrubber for scrubbing and recovery.

[0041] The tube-side steam condensate enters the tube box 15 from the steam condensate inlet 13 and then evenly enters the heat exchange tube bundle, taking away the heat generated by the hydrolysis of methylammonium on the shell side. The steam condensate is heated to generate steam, which flows out from the steam outlet 16 and enters the low-pressure steam drum.

[0042] Figure 2 The tube sheet 11 is welded with a corrosion-resistant layer 17 and connected to the heat exchange tube bundle 8 through a welding structure.

[0043] The above is a further detailed description of the present invention and should not be considered as a limitation on the specific implementation of the present invention. For those skilled in the art, simple deductions or substitutions that do not depart from the concept of the present invention are within the scope of protection of the present invention.

Claims

1. A high-pressure methylammonium condenser, characterized in that include: Shell and heat exchange tube bundle and internal parts inside the shell; The bottom of the shell is provided with a methylammonium liquid inlet and a CO2 gas inlet, and the upper part is provided with a reaction liquid outlet and a gas outlet; the heat exchange tube bundle is a U-shaped tube structure, and the heat transfer medium carries away the heat generated by the hydrolysis of methylammonium through the heat exchange tube bundle; The internal parts include a high-efficiency tower tray; the downcomer is supported by the high-efficiency tower tray; The methylammonium liquid enters the shell side of the high-pressure methylammonium condenser from the methylammonium liquid inlet, and the raw gas enters the shell side of the high-pressure methylammonium condenser from the CO2 gas inlet; the methylammonium liquid is deflected in the high-efficiency tower tray, and the gas is collected in the skirt plate of the high-efficiency tower tray and flows upward along the gas phase channel of the tower tray. It reacts between the high-efficiency tower trays to produce methylammonium, and part of the methylammonium is hydrolyzed to produce urea. The urea methylammonium solution generated by the reaction finally flows out of the reaction liquid outlet, and the unreacted gas flows out of the gas outlet. The high-efficiency tray is distributed in a baffled manner in the shell side of the high-pressure methylammonium condenser, the gap between the high-efficiency tray and the shell is a liquid phase channel, and a gas phase channel is provided on the high-efficiency tray; The gas phase channel is a distribution hole with a diameter of 3-4 mm opened in the central area supported by the baffle and the non-support area; The top of the high-pressure methylammonium condenser is provided with a pipe box, which is provided with a tube side inlet and an outlet. The heat-conducting medium steam condensate is forced to circulate through a steam condensate pump and enters from the tube side inlet, then enters the tube bundle, takes away the heat generated by the hydrolysis of methylammonium on the shell side, and the steam condensate is heated to generate steam, which flows out from the outlet. The internal components also include a downcomer, which is arranged in the high-efficiency tower tray and is used to circulate unreacted materials. The downcomer is supported by the high-efficiency tower tray and is a thin-walled non-pressure-bearing structure with a vortex breaker on the top. The internal parts also include a methylammonium liquid inlet distributor and a gas inlet distributor; the methylammonium liquid inlet is provided with a methylammonium liquid inlet distributor, and the CO2 gas inlet is provided with a gas inlet distributor, so that the methylammonium liquid and CO2 are evenly distributed and then enter the shell side of the high-pressure methylammonium condenser.

2. The high-pressure methylammonium condenser according to claim 1, characterized in that: The high-efficiency tower plate is provided with a skirt plate and an anti-short-circuit baffle; the skirt plate is used to collect gas and make the gas flow along the gas phase channel; the anti-short-circuit baffle is used to prevent the shell side fluid from short-circuiting and the fluid from flowing out directly without passing through the surface of the shell side heat exchange tube.

3. The high-pressure methylammonium condenser according to claim 2, characterized in that: A path partition is provided in the pipe box.

4. The high-pressure methylammonium condenser according to claim 1, characterized in that: The methylammonium liquid inlet distributor and the gas inlet distributor are distribution plates with distribution holes or inner extension pipe structures with distribution holes.

5. The high-pressure methylammonium condenser according to claim 1, characterized in that: The high-pressure methylammonium condenser is a vertical reactor, which is supported by a skirt support, an ear support, or a rigid ring support.

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