A process system for preventing reactor temperature from running high

Abstract

The present invention relates to a process system for preventing reactor temperature runaway, comprising a heat transfer material storage, separation, and circulation subsystem and a feed subsystem. The heat transfer material storage, separation, and circulation subsystem comprises a fractionating tower, a fractionating tower reboiler, a fractionating tower condenser, and a heat transfer material buffer tank. The fractionating tower reboiler and the fractionating tower condenser are respectively connected to the bottom and top of the fractionating tower, and the heat transfer material buffer tank is connected to the top outlet of the fractionating tower. The feed subsystem comprises a heat exchanger, a droplet dispersion device, and a thermocouple. The heat exchanger is respectively connected to the heat transfer material buffer tank and the droplet dispersion device, and the thermocouple is connected to the connecting pipe between the heat exchanger and the droplet dispersion device. Compared with the prior art, the present invention can effectively solve the problem of reactor temperature runaway and ensure stable reaction progress.

Description

Technical Field

[0001] The invention relates to a chemical process system, in particular to a process system for preventing a reactor from overheating. Background Art

[0002] In the chemical industry, highly exothermic reactions can be difficult to remove when using tubular reactors or adiabatic fixed-bed reactors. Within a certain area, even slight variations in operating parameters can cause the catalyst bed to reach ignition temperatures. If not addressed promptly, this can lead to reactor temperature spikes.

[0003] Temperature runaway causes localized overheating of the bed and a momentary loss of temperature control. The high temperature rapidly solidifies the catalyst, rapidly increasing the pressure differential across the catalyst bed. If not controlled promptly, this can ultimately lead to catalyst bed melting, damaging the reactor and potentially causing an accident. Temperature runaway negatively impacts conversion, selectivity, catalyst activity, and lifespan. Therefore, temperature runaway is one of the most critical issues in reactor design and operation.

[0004] Under certain operating conditions, whether a reaction system experiences a temperature runaway depends on the relationship between the system's heat generation rate and heat removal rate before ignition. Common measures to avoid this risk include: emergency nitrogen injection, lowering the reactor inlet temperature, and reducing reactor load.

[0005] Current safety measures for preventing reactor temperature runaway have the following issues: 1. Reaction lags, leading to a high probability of misoperation. 2. They generally rely on empirical procedures, which, when applied and controlled based on experience, can make reactor temperature runaway accidents difficult to avoid. Therefore, a process system to prevent reactor temperature runaway is essential. Summary of the Invention

[0006] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide a process system for preventing the temperature of the reactor from running high, thereby solving the problem of temperature running high in the reactor and making the reaction proceed stably.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] A process system for preventing reactor temperature from rising, comprising a heat transfer material storage, separation and circulation subsystem and a feed subsystem.

[0009] The heat transfer material storage, separation and circulation subsystem consists of a fractionating tower, a fractionating tower reboiler, a fractionating tower condenser and a heat transfer material buffer tank. The fractionating tower reboiler and the fractionating tower condenser are respectively connected to the bottom and top of the fractionating tower, and the heat transfer material buffer tank is connected to the top outlet of the fractionating tower.

[0010] The feeding subsystem consists of a heat exchanger, a droplet dispersion device, and a thermocouple. The heat exchanger is connected to the heat transfer material buffer tank and the droplet dispersion device respectively, and the thermocouple is connected to the connecting pipe between the heat exchanger and the droplet dispersion device.

[0011] A heat transfer material output pump is provided on the connecting pipeline between the heat transfer material buffer tank and the fractionating tower.

[0012] A heat transfer material feed pump is provided on the connecting pipe between the heat transfer material buffer tank and the heat exchanger.

[0013] A heat transfer material preheater is also provided on the connecting pipe between the heat exchanger and the droplet dispersion device.

[0014] A regulating valve is connected to the heating medium outlet of the heat transfer material preheater.

[0015] The droplet dispersion device is placed in the reactor.

[0016] A saturated heat transfer material is added to the reactor, utilizing its latent heat of vaporization to lower the catalyst bed's ignition point, thereby protecting the catalyst. The heat transfer material can be a product of the reaction or an inert substance that does not participate in the reaction. If an inert substance is used, it must be easily separated from the reaction products. The boiling point of the heat transfer material at the reaction pressure is the starting temperature of the catalyst's ignition point.

[0017] The reaction discharge is used for distillation range cutting. After the heat transfer material is cut out, it is pressurized and heat-exchanged to the bubble point under the reaction pressure before being returned to the reactor. A droplet dispersion device is used to disperse the heat transfer material into a mist. When the reactor reaches the ignition point, the mist droplets, at the bubble point, absorb the surrounding heat and quickly vaporize, removing excess reaction heat, thereby controlling the reaction temperature below the ignition point and preventing temperature runaway.

[0018] A certain proportion of the reaction discharge is distilled and cut into sections to produce a heat transfer material. The initial distillation point of the heat transfer material at the reaction pressure is the reactor's ignition point, and the final distillation point is 1-10°C above the reactor's ignition point. The heat transfer material is pressurized by a pump and, after exchanging heat with the reaction discharge, enters a preheater for heating. Temperature control is used to heat the heat transfer material to the bubble point at the reaction pressure. The heat transfer material then enters the reactor through a droplet dispersion device, where it is evenly distributed across each reaction tube or catalyst inlet cross-section. To ensure effective dispersion, the pressure differential between the inlet and outlet of the droplet dispersion device is 0.3-0.4 MPa.

[0019] The heat transfer material can be added to the reactor intermittently or continuously. If an intermittent addition scheme is adopted, when a certain proportion of temperature measuring points in the reactor detect overtemperature, the heat transfer material addition pump will be automatically started to pump the heat transfer material into the reactor; if the heat transfer material is added to the reactor continuously, when the reaction proceeds normally, since the bubble point temperature of the heat transfer material is above the reaction temperature, the heat transfer material will not vaporize and will be directly used as the reaction discharge material. If the reaction temperature rises abnormally, since the heat transfer material is in a bubble point state and the droplets are very finely dispersed, after absorbing heat, it will quickly vaporize and carry away the reaction heat through the latent heat of vaporization, extinguishing local fire points and preventing the reactor from overheating.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] (1) The process system to prevent reactor temperature spikes solves the ignition problem of adiabatic fixed-bed reactors and tube-in-tube equalizing reactors, prevents reactor temperature spikes, and ensures smooth reaction.

[0022] (2) The heat transfer material can be cut out from the reaction product without introducing other substances into the system; or an inert material that can be easily separated from the reaction product can be added.

[0023] (3) The boiling point of the heat transfer material at the reaction pressure is the reaction ignition point temperature. Above the reaction temperature, it does not affect the normal operation of the reactor.

[0024] (4) The heat transfer material exchanges heat with the reaction discharge, reducing heat consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 1 is a process flow chart of the present invention applied in a tubular temperature-equalizing reactor in Example 1;

[0026] Figure 2 This is a process flow chart of the application of the present invention in an adiabatic fixed bed reactor in Example 2.

[0027] In the figure, 1-distillation tower, 2-distillation tower reboiler, 3-distillation tower condenser, 4-heat transfer material output pump, 5-heat transfer material buffer tank, 6-heat transfer material feed pump, 7-heat transfer material and reaction discharge heat exchanger, 8-heat transfer material preheater, 9-heating medium outlet regulating valve, 10-heat transfer material feed temperature display, 11-droplet dispersion device, 12-tube-in-tube temperature equalizing reactor, 13-adiabatic fixed bed reactor, 101-reaction discharge, 102-reaction discharge, 103-fore fraction, 104-heat transfer material, 105-tower bottom discharge, 201-reaction discharge, 202-reaction discharge, 203-fore fraction, 204-heat transfer material, 205-tower bottom discharge. DETAILED DESCRIPTION

[0028] The present invention will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several variations and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0029] A process system for preventing a reactor from overheating comprises a heat transfer material storage, separation and circulation subsystem and a feed subsystem.

[0030] The heat transfer material storage, separation and circulation subsystem consists of a distillation tower, a distillation tower reboiler, a distillation tower condenser and a heat transfer material buffer tank. The distillation tower reboiler and the distillation tower condenser are respectively connected to the bottom and top of the distillation tower. The heat transfer material buffer tank is connected to the top outlet of the distillation tower, and a heat transfer material output pump is provided on the connecting pipeline.

[0031] The feeding subsystem consists of a heat exchanger, a droplet dispersion device, and a thermocouple. The droplet dispersion device is placed in the reactor. The heat exchanger is connected to the heat transfer material buffer tank and the droplet dispersion device respectively. A heat transfer material feed pump is provided on the connecting pipe between the heat transfer material buffer tank and the heat exchanger. A heat transfer material preheater and a thermocouple are provided on the connecting pipe between the heat exchanger and the droplet dispersion device. A regulating valve is connected to the heating medium outlet of the heat transfer material preheater.

[0032] During operation, a saturated heat transfer material is added to the reactor. Its latent heat of vaporization lowers the ignition temperature of the catalyst bed, thereby protecting the catalyst. The heat transfer material can be the reaction product or an inert substance that does not participate in the reaction. If an inert substance is used, it must be easily separated from the reaction products. The boiling point of the heat transfer material at the reaction pressure is the starting temperature of the catalyst's ignition point.

[0033] The reaction discharge is used for distillation range cutting. After the heat transfer material is cut out, it is pressurized and heat-exchanged to the bubble point under the reaction pressure before being returned to the reactor. A droplet dispersion device is used to disperse the heat transfer material into a mist. When the reactor reaches the ignition point, the mist droplets, at the bubble point, absorb the surrounding heat and quickly vaporize, removing excess reaction heat, thereby controlling the reaction temperature below the ignition point and preventing temperature runaway.

[0034] A certain proportion of the reaction discharge is distilled and cut into sections to produce a heat transfer material. The initial distillation point of the heat transfer material at the reaction pressure is the reactor's ignition point, and the final distillation point is 1-10°C above the reactor's ignition point. The heat transfer material is pressurized by a pump and, after exchanging heat with the reaction discharge, enters a preheater for heating. Temperature control is used to heat the heat transfer material to the bubble point at the reaction pressure. The heat transfer material then enters the reactor through a droplet dispersion device, where it is evenly distributed across each reaction tube or catalyst inlet cross-section. To ensure effective dispersion, the pressure differential between the inlet and outlet of the droplet dispersion device is 0.3-0.4 MPa.

[0035] The heat transfer material can be added to the reactor intermittently or continuously. If an intermittent addition scheme is adopted, when a certain proportion of temperature measuring points in the reactor detect overtemperature, the heat transfer material addition pump will be automatically started to pump the heat transfer material into the reactor; if the heat transfer material is added to the reactor continuously, when the reaction proceeds normally, since the bubble point temperature of the heat transfer material is above the reaction temperature, the heat transfer material will not vaporize and will be directly used as the reaction discharge material. If the reaction temperature rises abnormally, since the heat transfer material is in a bubble point state and the droplets are very finely dispersed, after absorbing heat, it will quickly vaporize and carry away the reaction heat through the latent heat of vaporization, extinguishing local fire points and preventing the reactor from overheating.

[0036] The following are more detailed implementation cases, which further illustrate the technical solutions of the present invention and the technical effects that can be obtained.

[0037] Example 1

[0038] like Figure 1 As shown, in a certain Fischer-Tropsch synthesis reaction design, the process is optimized by using the present invention, and the specific operations are as follows.

[0039] After heat exchange, 5 wt% of the reaction discharge 102 enters the fractionation tower 1, where it undergoes range cutting. Heat is replenished in the fractionation tower reboiler 2, and the cut heat transfer material 104 is condensed in the fractionation tower condenser 3. It is then transported to the heat transfer material buffer tank 5 via the heat transfer material output pump 4. The heat transfer material feed pump 6 is used to increase the pressure, and the heat transfer material passes through the heat transfer material and reaction discharge heat exchanger 7 and the heat transfer material preheater 8. By controlling the heating medium outlet regulating valve 9, the heat transfer material feed temperature display 10 is adjusted to the bubble point temperature at the reaction pressure. The preheated heat transfer material passes through the droplet dispersion device 11 and enters the shell and tube temperature equalization reactor 12. The fore fraction 103 and the bottom discharge 105 of the fractionation tower 1 are subsequently mixed with the cooled and depressurized reaction discharge 101.

[0040] The operating pressure of the tubular temperature-equalizing reactor 12 is 3.4 MPaG, and the operating temperature is 250°C. The operating pressure of the fractionating tower 1 is atmospheric pressure, the cut-off distillation range is 70-80°C, and the bubble point of the heat transfer material at the reaction pressure is 260°C. By controlling the preheater heating medium outlet regulating valve 9, the heat transfer material feed temperature display 10 is set to 260°C. To ensure the droplet dispersion effect, the inlet pressure of the heat transfer material at the droplet dispersion device 11 is controlled at 3.7-3.8 MPaG. By using this process system, the reaction ignition point can be effectively extinguished, the reactor temperature can be avoided, and the reaction can proceed smoothly.

[0041] Example 2

[0042] like Figure 2As shown in the figure, in a hydrogenation reaction design, the above process system is used to optimize the design of the process, and the specific operations are as follows.

[0043] After heat exchange, the 5wt% reaction discharge 202 enters fractionation tower 1, where it undergoes range cutting. Heat is replenished in fractionation tower reboiler 2, and the cut heat transfer material 204 is condensed in fractionation tower condenser 3. It is then pumped into heat transfer material buffer tank 5 via heat transfer material output pump 4. A heat transfer material feed pump 6 is used to increase pressure, and the material passes through heat transfer material and reaction discharge heat exchanger 7 and heat transfer material preheater 8. By controlling heating medium outlet regulating valve 9, the heat transfer material feed temperature display 10 is adjusted to the bubble point temperature at the reaction pressure. The preheated heat transfer material passes through droplet dispersion device 11 and enters adiabatic fixed-bed reactor 13. The fore fraction 203 and bottom discharge 205 of fractionation tower 1 are subsequently combined with the cooled and depressurized reaction discharge 201.

[0044] The operating pressure of the adiabatic fixed-bed reactor 13 is 1.0 MPaG, and the operating temperature is 140°C. The operating pressure of the fractionating tower 1 is 0.05 MPaG, the cut-off distillation range is 65-70°C, and the bubble point of the heat transfer material at the reaction pressure is 150°C. By controlling the preheater heating medium outlet regulating valve 9, the heat transfer material feed temperature display 10 is 150°C. To ensure the droplet dispersion effect, the inlet pressure of the heat transfer material at the droplet dispersion device 11 is controlled at 1.3-1.4 MPaG. By using this process system, the reaction ignition point can be effectively extinguished, the reactor temperature can be avoided, and the reaction can proceed smoothly.

[0045] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0046] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention, without departing from the scope of the present invention, should be within the scope of protection of the present invention.

Claims

1. A process system for preventing reactor temperature from running high, characterized in that: The process system includes a heat transfer material storage, separation and circulation subsystem and a feed subsystem. The heat transfer material storage, separation and circulation subsystem consists of a fractionating tower, a fractionating tower reboiler, a fractionating tower condenser and a heat transfer material buffer tank. The fractionating tower reboiler and the fractionating tower condenser are respectively connected to the bottom and top of the fractionating tower, and the heat transfer material buffer tank is connected to the top outlet of the fractionating tower. The feeding subsystem consists of a heat exchanger, a droplet dispersion device, and a thermocouple. The heat exchanger is connected to the heat transfer material buffer tank and the droplet dispersion device respectively. The thermocouple is connected to the connecting pipe between the heat exchanger and the droplet dispersion device. A heat transfer material preheater is further provided on the connecting pipe between the heat exchanger and the droplet dispersion device, and the heat transfer material preheater heats the returned heat transfer material to the bubble point temperature under the reaction pressure, and then enters the reactor through the droplet dispersion device; A heat transfer substance in a saturated state is added into the reactor through a droplet dispersion device; the droplet dispersion device is an atomizer; The heat transfer material is a reaction product, the initial distillation point of the heat transfer material under the reaction pressure is the ignition point of the reactor, and the final distillation point is 1 to 10° C. above the ignition point temperature of the reactor.

2. A process system for preventing reactor temperature runaway according to claim 1, characterized in that: A heat transfer material output pump is provided on the connecting pipeline between the heat transfer material buffer tank and the fractionating tower.

3. A process system for preventing reactor temperature runaway according to claim 1, characterized in that: A heat transfer material feed pump is provided on the connecting pipe between the heat transfer material buffer tank and the heat exchanger.

4. A process system for preventing reactor temperature runaway according to claim 1, characterized in that: A regulating valve is connected to the heating medium outlet of the heat transfer material preheater.

5. A process system for preventing reactor temperature runaway according to claim 1, characterized in that: The droplet dispersion device is placed in the reactor.

6. A process system for preventing reactor temperature runaway according to claim 1 or 5, characterized in that: The reaction discharge from the reactor enters the fractionation tower after heat exchange treatment in a heat exchanger.

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