A waste heat recovery and utilization device in a dangerous chemical reaction process

Abstract

The utility model relates to the technical field of dangerous chemical production waste heat recovery, and disclose a kind of waste heat recovery and utilization device in dangerous chemical reaction process, including the heat exchanger shell being connected with chemical reaction kettle, symmetrical connection is used for sealing tube sheet in heat exchanger shell, the end portion of heat exchanger shell away from chemical reaction kettle is fixedly connected with head, further include: equidistant and staggered installation in heat exchanger shell are used for the baffle of flow guide;The utility model solves the impurity deposition problem caused by waste heat medium inlet flow rate sudden change in the prior art, avoids the situation that laminar flow is easily formed in straight-line smooth heat exchange tube, and heat transfer is slow, and conical tube can make medium flow rate gentle transition, avoid the impurity adhesion caused by flow rate sudden change, significantly reduce the impurity deposition of inlet section, flow guide plate and triangular gap can break the laminar flow state of medium, promote to form turbulent flow, speed up heat transfer speed, substantially improve the efficiency of tube pass heat exchange.

Description

Technical Field

[0001] This utility model relates to the field of waste heat recovery technology in hazardous chemical production, specifically a waste heat recovery and utilization device in the reaction process of hazardous chemicals. Background Technology

[0002] In the field of hazardous chemical production, typical reactions such as benzene nitration and ammonia synthesis continuously release a large amount of heat. The waste heat medium discharged after the reaction is mostly a gas-liquid mixture at 180-250°C. Directly discharging these high-temperature waste heat media would result in a serious waste of energy. On the other hand, the high-temperature waste heat media are in direct contact with the external environment, which can easily cause safety hazards. For example, the high temperature may cause burns to operators, and some hazardous chemical media (such as nitrobenzene, ammonia, etc.) may also cause air pollution or poisoning risks due to volatilization at high temperatures. Therefore, it is crucial to recover and utilize the waste heat in the process of hazardous chemical reactions.

[0003] Currently, in the industrial sector, shell-and-tube heat exchangers are the mainstream equipment for recovering waste heat from hazardous chemical reactions. These heat exchangers use a tube-side flow of waste heat medium and a shell-side flow of heat transfer medium, such as heat transfer oil or cooling water, to transfer heat from the waste heat medium to the heat transfer medium. The heat-absorbing heat transfer medium is then used for preheating reaction raw materials, workshop heating, and other applications, thus achieving the secondary utilization of waste heat.

[0004] However, existing shell-and-tube heat exchangers have certain problems in the scenario of waste heat recovery from hazardous chemical reactions. On the one hand, some tubes use pure straight smooth heat exchange tubes. Because the hazardous chemical waste heat medium contains trace amounts of reactant residues, its viscosity is slightly higher than that of ordinary industrial media. When flowing in straight tubes, it is easy to form a laminar flow state, resulting in slow heat transfer and low heat exchange efficiency. On the other hand, when the trace viscous impurities contained in the waste heat medium enter the heat exchange tubes, some tube inlets do not have guiding structures, which causes the medium flow rate to suddenly decrease. This makes it easy for impurities to be deposited on the tube wall in the tube inlet section. Therefore, we urgently need a waste heat recovery and utilization device in the process of hazardous chemical reactions to solve the above problems. Utility Model Content

[0005] This utility model provides a waste heat recovery and utilization device in the reaction process of hazardous chemicals. By setting up a tapered tube inside a U-shaped tube, a guide plate and a variable diameter setting on the inner wall, it solves the problems of slow laminar heat exchange and inlet impurity deposition in the tube side mentioned in the background art.

[0006] This utility model provides the following technical solution: A waste heat recovery and utilization device for a hazardous chemical reaction process includes a heat exchanger shell connected to a chemical reactor. A tube sheet for sealing is symmetrically connected inside the heat exchanger shell. A head is fixedly connected to the end of the heat exchanger shell away from the chemical reactor. The device also includes baffles equidistantly and alternately installed inside the heat exchanger shell for flow guidance; and a U-shaped heat exchange tube fixedly installed inside the heat exchanger shell for conveying the waste heat medium, with a flow guide section inside the U-shaped heat exchange tube for guiding the waste heat medium.

[0007] As a preferred technical solution of this utility model, the flow guiding part includes a tapered tube disposed at both ends of the U-shaped heat exchange tube to suppress impurity deposition. The large-diameter end of the tapered tube is fixedly installed at the end of the U-shaped heat exchange tube, and the small-diameter end of the tapered tube is fixedly connected to the inner wall of the U-shaped heat exchange tube.

[0008] As a preferred technical solution of this utility model, the U-shaped heat exchange tube is mainly composed of a straight pipe section and a bent pipe section. The inner wall of the straight pipe section is provided with at least two sets of guide plates for improving heat transfer. The two sets of guide plates are arranged equidistantly in a ring along the axis of the straight pipe section.

[0009] As a preferred technical solution of this utility model, the end of the guide plate is provided with a triangular notch for forming vortices, and at least two sets of blades for reducing drag are symmetrically installed on the guide plate, with the two sets of blades arranged at equal intervals on the guide plate.

[0010] As a preferred technical solution of this utility model, the inner diameter of the straight pipe section ranges from 30mm to 35mm, and the inner diameter of the bent pipe section ranges from 23mm to 28mm.

[0011] As a preferred embodiment of this utility model, the inner wall of the heat exchanger shell is equidistantly equipped with arc-shaped plates for increasing flow velocity.

[0012] As a preferred embodiment of this utility model, the cross-sectional projection of the baffle plate is elliptical.

[0013] As a preferred technical solution of this utility model, the straight pipe section is installed on two sets of tube sheets and baffles, and the two ports of the straight pipe section are connected to the corresponding tube sheets. The bent pipe section is located in the cavity inside the head to form a U-shaped flow channel.

[0014] Compared with the prior art, this utility model provides a waste heat recovery and utilization device in the reaction process of hazardous chemicals, which has the following beneficial effects: 1. In this waste heat recovery and utilization device during the reaction of hazardous chemicals, a tapered tube is set at the port of the U-shaped heat exchange tube, which, together with the guide plate and triangular notch on the inner wall of the straight tube section, solves the problem of impurity deposition caused by sudden changes in the inlet flow velocity of the waste heat medium in the prior art. It avoids the situation where laminar flow and slow heat transfer are easily formed in straight smooth heat exchange tubes. Moreover, the tapered tube can make the medium flow velocity transition smoothly, avoid impurity adhesion caused by sudden changes in flow velocity, significantly reduce impurity deposition in the inlet section, and the guide plate and triangular notch can break the laminar flow state of the medium, promote the formation of turbulence, accelerate the heat transfer speed, and greatly improve the tube heat exchange efficiency.

[0015] 2. In this waste heat recovery and utilization device for hazardous chemical reactions, the combination design of baffles and arc-shaped plates on the inner wall of the shell solves the problems of multiple dead zones in the shell flow, uneven medium distribution, and short circuits in the tube medium. The baffles can guide the cooling medium to flow smoothly, reduce dead zones in the shell, and avoid local medium stagnation. The arc-shaped plates can increase the flow velocity of the medium in the shell and enhance the contact effect between the medium and the outer wall of the heat exchange tube, effectively improving the uniformity of heat exchange in the shell and the overall waste heat recovery efficiency.

[0016] The parts of this device not covered are the same as or can be implemented using existing technologies. This utility model solves the problem of impurity deposition caused by sudden changes in the inlet flow rate of the waste heat medium in the prior art, avoids the situation that laminar flow and slow heat transfer are easy to form in straight smooth heat exchange tubes, thereby improving the heat exchange efficiency. It can also make the cooling medium flow smoothly, reduce the shell dead zone, avoid local medium stagnation, and enhance the contact effect between the medium and the outer wall of the heat exchange tube. Attached Figure Description

[0017] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, the elements or parts are not necessarily drawn to actual scale.

[0018] Figure 1 This is a schematic diagram of the overall structure of this utility model; Figure 2 This is a schematic diagram of a partial structure of the present invention. Figure 1 ; Figure 3 This is a partial cross-sectional view of the present invention. Figure 1 ; Figure 4 This is a schematic diagram of a partial structure of the present invention. Figure 2 ; Figure 5 This is a schematic diagram of a partial structure of the present invention. Figure 3 ; Figure 6 This is a partial cross-sectional view of the present invention. Figure 2 ; Figure 7 This utility model Figure 6 Enlarged structural diagram at point A in the middle; Figure 8 This utility model Figure 6 Enlarged structural diagram at point B.

[0019] In the figure: 1. Heat exchanger shell; 2. Tube sheet; 3. End cap; 4. Baffle plate; 5. U-shaped heat exchange tube; 6. Conical tube; 7. Guide plate; 8. Triangular notch; 9. Blade; 10. Arc plate. Detailed Implementation

[0020] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0021] Example: Reference Figure 1 - Figure 8 A waste heat recovery and utilization device in the reaction process of hazardous chemicals includes a heat exchanger shell 1 connected to a chemical reaction vessel. The heat exchanger shell 1 is made of 316L stainless steel and has a horizontal cylindrical structure.

[0022] The heat exchanger shell 1 is symmetrically connected with tube sheets 2 for sealing. The end of the heat exchanger shell 1 away from the chemical reactor is fixedly connected with a head 3. The inner wall of the heat exchanger shell 1 is equidistantly installed with arc-shaped plates 10 for increasing the flow rate.

[0023] Here, the tube sheet 2 on the heat exchanger shell 1 is provided with through holes adapted to the U-shaped heat exchange tubes 5. The area between the two sets of tube sheets 2 is the heat exchange area. Taking this embodiment as an example, one end of the heat exchanger shell 1 is provided with a waste heat medium inlet connected to the chemical reactor. Its inlet position is located below the heat exchanger shell 1 and is connected to the tube-side chamber in the heat exchanger shell 1. The pipe at the inlet is made of 316L stainless steel and is sealed to the waste heat medium outlet pipe of the reactor through a flange. Above the heat exchanger shell 1 and coaxial with the waste heat medium inlet, there is a waste heat medium outlet. Its outlet is connected to the tube-side chamber in the heat exchanger shell 1. The pipe at the outlet is made of 316L stainless steel and is connected to the subsequent processing equipment through a flange.

[0024] A cooling medium inlet is connected to the top of the heat exchanger shell 1. This inlet is directly connected to the heat exchange area, which is the shell-side chamber. The pipe at the inlet is made of 316L stainless steel and is connected to the cooling medium supply equipment through a flange. A cooling medium outlet is connected to the bottom of the heat exchanger shell 1. This outlet is directly connected to the heat exchange area. The pipe at the outlet is made of 316L stainless steel and is connected to the cooling medium utilization equipment through a flange.

[0025] Furthermore, the tube-side chamber is the area between the inner wall of the heat exchanger shell 1 and the tube sheet 2. A baffle plate is provided in the middle of the chamber, so that there are two spaces in the chamber: one space is used to connect the waste heat medium inlet pipe and the other space is used to connect the waste heat medium outlet pipe.

[0026] Furthermore, an arc-shaped plate 10 is provided on the heat exchanger shell 1, which can reduce the local flow area and increase the flow rate of the cooling medium, thereby improving the heat exchange efficiency of the shell side. In addition, the arc-shaped plate 10 can guide the cooling medium to flow towards the center of the shell, thereby reducing the heat exchange blind zone and ensuring uniform heat exchange of the entire tube bundle.

[0027] It should be noted that a stainless steel filter screen is welded to the inner wall of the pipe at the waste heat medium inlet to intercept solid impurities of the medium, such as catalyst particles that have fallen off from the reactor. A J41H-16C type shut-off valve is installed on the pipe at the waste heat medium inlet, and a pressure transmitter is installed after the valve to monitor the inlet pressure in real time. A bimetallic thermometer and a sampling port are installed on the pipe at the waste heat medium outlet. The sampling port is located 50mm downstream of the thermometer to facilitate simultaneous monitoring of temperature and medium composition.

[0028] Furthermore, the pipe from the cooling medium inlet extends into the shell-side chamber to allow the cooling medium to enter. A KV-type manual regulating butterfly valve is installed on the inlet pipe to control the flow rate of the cooling medium. A pressure gauge, thermometer, and spring-loaded safety valve are installed on the pipe from the cooling medium outlet. The outlet of the safety valve is connected to a vent pipe, leading to a safe outdoor area.

[0029] It also includes baffles 4 that are equidistantly and staggeredly installed inside the heat exchanger shell 1 for guiding the flow. The cross-sectional projection of the baffles 4 is elliptical.

[0030] In this embodiment, there are five sets of baffles 4 arranged in an alternating manner. The arc-shaped edge of the elliptical baffle 4 fits more closely with the inner wall of the shell. At the same time, the staggered installation and the opposite opening directions of adjacent plates can guide the cooling medium to flow in an "S" shape, thereby reducing the proportion of dead zones and improving the utilization rate of the cooling medium. This avoids the deterioration of the cooling medium caused by local overheating, such as the high-temperature coking of heat transfer oil. The smooth edge of the elliptical baffle 4 can make the transition of the cooling medium flow direction smoother, avoiding the turbulent impact of the medium caused by the right-angle edge of the traditional straight baffle 4.

[0031] A U-shaped heat exchange tube 5 is fixedly installed inside the heat exchanger shell 1 for conveying waste heat medium. A flow guide is provided inside the U-shaped heat exchange tube 5 for guiding the waste heat medium. The flow guide includes a tapered tube 6 provided at the two ends of the U-shaped heat exchange tube 5 for suppressing impurity deposition. The large-diameter end of the tapered tube 6 is fixedly installed to the end of the U-shaped heat exchange tube 5, and the small-diameter end of the tapered tube 6 is fixedly connected to the inner wall of the U-shaped heat exchange tube 5.

[0032] In this embodiment, the U-shaped heat exchange tube 5 can absorb thermal stress through the elastic deformation of the bent section, avoiding the pipe wall cracking caused by stress concentration in the straight pipe. The tapered tubes 6 on the two ends of the U-shaped heat exchange tube 5 can make the flow rate of the waste heat medium transition smoothly, thereby effectively reducing the deposition of impurities and avoiding blockage. The inclined surface of the inner wall of the tapered tube 6 can guide the waste heat medium to converge towards the center of the tube, keeping the mainstream area of ​​the waste heat medium away from the pipe wall, reducing the probability of impurities contacting the pipe wall, and ensuring the stability of the waste heat medium flow rate.

[0033] The U-shaped heat exchange tube 5 is mainly composed of straight tube sections and bent tube sections. The straight tube sections are installed on two sets of tube sheets 2 and baffles 4, and the two ends of the straight tube sections are connected to the corresponding tube sheets 2. The bent tube sections are located in the cavity inside the head 3 to form a U-shaped flow channel. The inner diameter of the straight tube sections ranges from 30mm to 35mm, and the inner diameter of the bent tube sections ranges from 23mm to 28mm.

[0034] In this embodiment, the diameter of the straight pipe section is 35mm and the diameter of the bend section is 28mm. With these dimensions, the medium flow rate can be guaranteed while reducing the eddy dead zone in the bend section and avoiding the accumulation of impurities in the bend section.

[0035] The inner wall of the straight pipe section is provided with at least two sets of guide plates 7 for improving heat transfer. The two sets of guide plates 7 are arranged equidistantly in a ring along the axis of the straight pipe section. The ends of the guide plates 7 are provided with triangular notches 8 for forming vortices. At least two sets of vanes 9 for reducing resistance are symmetrically installed on the guide plates 7. The two sets of vanes 9 are arranged equidistantly on the guide plates 7.

[0036] In this embodiment, the triangular notch 8 can divide the waste heat medium, forcing the medium to generate radial disturbance. Combined with the triangular notch 8, it forms a local vortex, further improving the heat exchange efficiency and waste heat recovery efficiency. The vane 9 can guide the medium to flow along the surface of the vane 9, reducing vortex resistance.

[0037] In this invention, the heat exchanger shell 1 is connected to the chemical reactor via a pipeline. The shell side is connected to the heat transfer medium. After checking the sealing of each component and stabilizing the reaction of the hazardous chemicals in the reactor, the pipeline valve is opened. The waste heat medium at 180-250°C, containing trace amounts of viscous impurities, enters the tube side of the heat exchanger shell 1. The waste heat medium is first smoothly introduced through the tapered tube 6 at the port of the U-shaped heat exchange tube 5. When it enters the straight tube section, the guide plate 7 and the triangular notch 8 disrupt the laminar flow and form turbulent flow. The heat is quickly transferred to the shell side through the tube wall. The medium is turned back through the bend section and flows out along another straight tube section. During the flow of the waste heat medium in the tube side, the heat transfer medium enters from the cooling medium inlet on the heat exchanger shell 1. It is guided by the elliptical baffle 4 to flow in an "S" shape and combined with the arc plate 10 to increase its own flow velocity. The cooling medium fully washes the outer wall of the U-shaped heat exchange tube 5 and then flows out from the cooling medium outlet of the heat exchanger shell 1, thus forming heat exchange.

[0038] Components not described in detail in this article are existing technologies.

[0039] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model.

Claims

1. A waste heat recovery and utilization device for a hazardous chemical reaction process, comprising a heat exchanger shell (1) connected to a chemical reaction vessel, wherein tube sheets (2) for sealing are symmetrically connected inside the heat exchanger shell (1), and a head (3) is fixedly connected to the end of the heat exchanger shell (1) away from the chemical reaction vessel, characterized in that, Also includes: baffles (4) are installed equidistantly and alternately inside the heat exchanger shell (1) for guiding flow. A U-shaped heat exchange tube (5) is fixedly installed inside the heat exchanger shell (1) for conveying waste heat medium. The U-shaped heat exchange tube (5) is provided with a flow guide for guiding the waste heat medium.

2. The waste heat recovery and utilization device in a hazardous chemical reaction process according to claim 1, characterized in that, The flow guide includes a tapered tube (6) disposed at both ends of the U-shaped heat exchange tube (5) to suppress impurity deposition. The large-diameter end of the tapered tube (6) is fixedly installed at the end of the U-shaped heat exchange tube (5), and the small-diameter end of the tapered tube (6) is fixedly connected to the inner wall of the U-shaped heat exchange tube (5).

3. The waste heat recovery and utilization device in a hazardous chemical reaction process according to claim 1, characterized in that, The U-shaped heat exchange tube (5) is mainly composed of a straight pipe section and a bent pipe section. The inner wall of the straight pipe section is provided with at least two sets of guide plates (7) for improving heat transfer. The two sets of guide plates (7) are arranged equidistantly in a ring along the axis of the straight pipe section.

4. The waste heat recovery and utilization device in a hazardous chemical reaction process according to claim 3, characterized in that, The end of the guide plate (7) is provided with a triangular notch (8) for forming vortices, and at least two sets of blades (9) for reducing drag are symmetrically installed on the guide plate (7). The two sets of blades (9) are arranged at equal intervals on the guide plate (7).

5. A waste heat recovery and utilization device for a hazardous chemical reaction process according to claim 3, characterized in that, The inner diameter of the straight pipe section ranges from 30mm to 35mm, while the inner diameter of the bend pipe section ranges from 23mm to 28mm.

6. The waste heat recovery and utilization device in a hazardous chemical reaction process according to claim 1, characterized in that, The inner wall of the heat exchanger shell (1) is equidistantly fitted with arc-shaped plates (10) for increasing flow velocity.

7. The waste heat recovery and utilization device in a hazardous chemical reaction process according to claim 1, characterized in that, The cross-sectional projection of the baffle (4) is elliptical.

8. A waste heat recovery and utilization device for a hazardous chemical reaction process according to claim 1, characterized in that, The straight pipe section is installed on two sets of tube sheets (2) and baffles (4), and the two ports of the straight pipe section are connected to the corresponding tube sheets (2). The bent pipe section is located in the cavity inside the head (3) to form a U-shaped flow channel.

Images