Methanol synthesis reactor outlet heat energy gradient recycling device and method

Abstract

The invention discloses a methanol synthesis reactor outlet heat energy gradient recycling device which comprises a standard plate heat exchanger arranged on a methanol synthesis reactor outlet pipeline, the standard plate heat exchanger comprises a first-stage recycling section and a second-stage recycling section, the first-stage recycling section is connected to the side close to the methanol synthesis reactor outlet, and the second-stage recycling section is connected to the side close to the methanol synthesis reactor outlet. The secondary recovery section is arranged on one side, far away from the methanol synthesis reactor, of the primary recovery section and is used for supplying waste heat of output gas output by the primary recovery section to a domestic hot water system. Through innovative combination of cascade temperature division logic and standard equipment embedding, the heat energy recovery rate is improved, the cost is reduced by more than 70% by adopting standard equipment, the annual benefit reaches 9000000 yuan, the investment payoff period is only about 1.1 years, good economic benefits are achieved, the reactor structure does not need to be changed, system shutdown does not need to be carried out, and plug-and-play is achieved.

Description

Technical Field

[0001] This invention relates to a device and method for cascade recovery and utilization of heat energy at the outlet of a methanol synthesis reactor, belonging to the field of methanol production technology. Background Technology

[0002] In the methanol synthesis process, the high-temperature gas produced at the reactor outlet, typically ranging from 150°C to 250°C, carries a significant amount of usable thermal energy. However, current industrial practices show a significant deficiency in the recovery and utilization of this thermal energy. Traditional treatment methods mainly fall into two categories, both of which suffer from fundamental technical defects:

[0003] The first approach is a heat recovery-free scheme, where the reactor outlet gas is directly discharged after necessary subsequent processing or released after simple cooling. While this scheme has a simple system structure and requires no additional investment, it results in virtually zero thermal energy utilization, leading to significant energy waste and directly translating into high operating costs.

[0004] The second approach is a customized heat recovery solution, which attempts to recover some heat energy by installing customized heat exchange equipment. However, it has several inherent drawbacks: First, it typically uses a single heat exchange process, failing to utilize heat energy in stages according to the temperature gradient of the heat source. This results in low efficiency in recovering waste heat in the medium and low temperature ranges, with an overall heat recovery rate usually below 40%. Second, the heat exchangers used are mostly non-standard customized equipment, leading to high procurement costs and complex installation and integration processes. This often requires modifications to the existing reactor system, necessitating shutdowns for construction, causing production interruptions, and resulting in a long overall implementation cycle.

[0005] In summary, existing technologies generally lack a mature solution that can achieve efficient, cascaded recovery of heat energy from the methanol synthesis reactor outlet using standardized, low-cost equipment without altering the reactor's main structure or requiring system shutdown. Summary of the Invention

[0006] The purpose of this invention is to provide a device for the cascade recovery and utilization of heat energy at the outlet of a methanol synthesis reactor, and a method for using the device. This invention aims to solve the technical bottlenecks in the prior art, such as low heat recovery efficiency, high implementation cost, and poor compatibility with existing processes due to the need for system shutdown and customized equipment.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a methanol synthesis reactor outlet heat energy cascade recovery and utilization device, comprising:

[0008] A standard plate heat exchanger is installed on the outlet pipe of the methanol synthesis reactor. The standard plate heat exchanger is an ASME certified standard plate heat exchanger, which includes a primary recovery section and a secondary recovery section.

[0009] The primary recovery section is connected near the outlet of the methanol synthesis reactor. The hot medium flow channel of the primary recovery section is connected to the outlet of the methanol synthesis reactor, and its cold medium flow channel is connected to the feed gas pipeline of the methanol synthesis reactor. It is used to preheat the feed gas of the methanol synthesis reactor by passing the heat of the high-temperature gas output from the outlet of the methanol synthesis reactor at 150-180°C through the primary recovery section.

[0010] The secondary recovery section is located on the side of the primary recovery section away from the methanol synthesis reactor. The hot medium channel of the secondary recovery section is connected to the outlet of the hot medium channel of the primary recovery section, and its cold medium channel is connected to a water pipe of the domestic hot water system. The waste heat of the gas output from the primary recovery section at a temperature below 80°C is supplied to the domestic hot water system through the secondary recovery section.

[0011] The aforementioned device further includes a temperature control system, the temperature control system comprising:

[0012] The first and second temperature sensor groups are installed at the inlet and outlet of the primary recycling section.

[0013] The third and fourth temperature sensor groups are installed at the inlet and outlet of the secondary recovery section;

[0014] A PLC controller that is respectively connected to the signals of the first temperature sensor group, the second temperature sensor group, the third temperature sensor group, and the fourth temperature sensor group;

[0015] The gas regulating valve is installed on the feed gas pipeline and the liquid regulating valve is installed on the domestic hot water pipeline. Both the gas regulating valve and the liquid regulating valve are connected to the PLC controller via signals.

[0016] The PLC controller is used to receive signals from each temperature sensor group and adjust the fluid flow rate by controlling the opening of the gas regulating valve and the liquid regulating valve, so that the outlet temperature control accuracy of the first-stage recovery section is ±0.5℃ and the outlet temperature control accuracy of the second-stage recovery section is ±1.0℃.

[0017] The aforementioned device's temperature control system is continuously verified through Aspen Plus process simulation software to ensure a stable heat recovery rate.

[0018] In the aforementioned apparatus, the target temperature of the feed gas to the methanol synthesis reactor is 80-100°C, and it is stably supplied through a primary recovery section.

[0019] In the aforementioned device, the target temperature of the domestic hot water is 65-75℃, and it is stably supplied through a two-stage recovery section.

[0020] A method for cascade recovery and utilization of heat energy from the outlet of a methanol synthesis reactor includes the following steps:

[0021] The high-temperature gas at 150-250℃ from the methanol synthesis reactor outlet is introduced into a standard plate heat exchanger.

[0022] In the primary recovery section of the standard plate heat exchanger, primary heat exchange is carried out to transfer the heat of the 150-180℃ high-temperature gas to the feed gas, so that the feed gas is preheated to 80-100℃.

[0023] In the secondary recovery section of the standard plate heat exchanger, secondary heat exchange is carried out to transfer the waste heat below 80°C to the domestic hot water, so that the domestic hot water temperature reaches 65-75°C.

[0024] The aforementioned method, wherein steps B and C are performed through a temperature control system to achieve precise temperature control, includes:

[0025] The inlet and outlet temperatures of the primary recovery section are monitored in real time using the first and second temperature sensor groups.

[0026] The inlet and outlet temperatures of the secondary recovery section are monitored in real time using the third and fourth temperature sensor groups.

[0027] The PLC controller processes the temperature signal and calculates the deviation from the target temperature.

[0028] The PLC controller outputs control signals to dynamically adjust the opening of the regulating valves on the feed gas pipeline and the domestic hot water pipeline to control the fluid flow.

[0029] In the aforementioned method, the outlet temperature control accuracy of the primary recovery section is ±0.5℃, and the outlet temperature control accuracy of the secondary recovery section is ±1.0℃.

[0030] The aforementioned method further includes a continuous operation verification step using Aspen Plus process simulation software to achieve precise data control.

[0031] Compared with the prior art, the present invention has at least the following beneficial effects:

[0032] (1) This invention upgrades the traditional single and extensive heat recovery mode to a refined graded utilization by using the tiered temperature division logic. The first stage recovers high-temperature heat energy, and the second stage recovers low-temperature waste heat, so that the overall heat recovery rate jumps from less than 40% in the traditional scheme to more than 78%, an increase of more than 78 percentage points, achieving a leapfrog growth in energy utilization and greatly improving heat recovery efficiency.

[0033] (2) The core equipment of the system of this invention adopts the standard plate heat exchanger certified by ASME. Compared with the customized solution, the equipment cost is reduced by more than 70%. At the same time, the heat recovery rate of up to 78% can bring an annual benefit of about RMB 9 million, which shortens the investment payback period to about 1.1 years and solves the problem of poor economic efficiency caused by high investment and low returns in traditional solutions.

[0034] (3) The present invention adopts the "standard equipment embedding" technology, which does not require any modification to the existing reactor structure and does not require system shutdown during the installation process. It completely overcomes the fatal defects of customized solutions that require production shutdown and long implementation cycle. This solution can achieve "plug and play", shortening the implementation cycle from several months to several days, providing great convenience for the energy-saving transformation of existing equipment. It is a standardized solution that can be quickly replicated.

[0035] (4) This invention provides a scientific and reliable basis for the optimized operation of the system and the adjustment of process parameters through precise temperature segment control, which makes heat energy recovery move from experience-based to precision, and greatly enhances the predictability and controllability of the technology. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the device structure of the present invention;

[0037] Figure 2 This is an overall flowchart of the method of the present invention;

[0038] Figure 3 This is a schematic diagram of the device system of the present invention.

[0039] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Detailed Implementation

[0040] Embodiment 1 of the present invention:

[0041] A cascade recovery and utilization device for the outlet heat energy of a methanol synthesis reactor includes:

[0042] A standard plate heat exchanger is installed on the outlet pipe of the methanol synthesis reactor. This standard plate heat exchanger adopts the ASME certified standard plate heat exchanger, and its cost is less than 150,000 yuan. It is not a customized device. The outlet pipe diameter of the methanol synthesis reactor is DN200. The installation of the ASME certified standard plate heat exchanger does not require modification of the reactor structure. The installation process does not require shutdown. The heat recovery system can be quickly deployed simply by adding the standard plate heat exchanger to the existing pipeline.

[0043] The heat energy cascade recovery system is constructed using standard plate heat exchangers, including a primary recovery stage and a secondary recovery stage.

[0044] The primary recovery section is connected near the outlet of the methanol synthesis reactor. The hot medium flow channel of the primary recovery section is connected to the outlet of the methanol synthesis reactor, and its cold medium flow channel is connected to the feed gas pipeline of the methanol synthesis reactor. It is used to preheat the feed gas of the methanol synthesis reactor by passing the heat of the high-temperature gas output from the outlet of the methanol synthesis reactor at 150-180°C through the primary recovery section. The target temperature of the feed gas is 80-100°C, and it is stably supplied through the primary recovery section.

[0045] The secondary recovery section is located on the side of the primary recovery section away from the methanol synthesis reactor. The hot medium flow channel of the secondary recovery section is connected to the outlet of the hot medium flow channel of the primary recovery section, and its cold medium flow channel is connected to the water pipe of the domestic hot water system. It is used to supply the waste heat of the gas output from the primary recovery section at a temperature below 80°C to the domestic hot water system through the secondary recovery section. The target temperature of the domestic hot water is 65-75°C, and it is stably supplied through the secondary recovery section.

[0046] Specifically, it also includes a temperature control system, which comprises:

[0047] The first and second temperature sensor groups are installed at the inlet and outlet of the primary recycling section.

[0048] The third and fourth temperature sensor groups are installed at the inlet and outlet of the secondary recovery section;

[0049] A PLC controller that is respectively connected to the signals of the first temperature sensor group, the second temperature sensor group, the third temperature sensor group, and the fourth temperature sensor group;

[0050] The gas regulating valve is installed on the feed gas pipeline and the liquid regulating valve is installed on the domestic hot water pipeline. Both the gas regulating valve and the liquid regulating valve are connected to the PLC controller via signals.

[0051] The PLC controller is used to receive signals from each temperature sensor group and adjust the fluid flow rate by controlling the opening of the gas regulating valve and the liquid regulating valve, so that the outlet temperature control accuracy of the first-stage recovery section is ±0.5℃ and the outlet temperature control accuracy of the second-stage recovery section is ±1.0℃.

[0052] Specifically, in the primary recovery section of a standard plate heat exchanger, the 150-180℃ high-temperature process gas from the reactor outlet flows through one channel, while the feed gas to be preheated flows through an adjacent channel. A first temperature sensor and a gas regulating valve controlled by a PLC controller are installed on the feed gas outlet pipe. The PLC receives the signal from the first temperature sensor and dynamically adjusts the opening of the gas regulating valve through a PID algorithm to control the feed gas flow rate, thereby precisely maintaining its outlet temperature within the range of 80-100℃, with a control accuracy of ±0.5℃.

[0053] In the secondary recovery section of the standard plate heat exchanger, the process gas (temperature below 80℃) cooled by the primary recovery continues to flow in the subsequent flow channel of the standard plate heat exchanger, transferring the remaining heat to the domestic water system. A second temperature sensor and a liquid regulating valve controlled by a PLC are installed on the domestic water outlet pipe. The PLC receives the signal from the second sensor and adjusts the opening of the liquid regulating valve to stabilize the domestic hot water temperature at 65-75℃ with a control accuracy of ±1.0℃.

[0054] The installation of this device requires no structural modifications to the reactor body; only openings and flange connections to the piping are needed. Through valve switching, the heat exchanger can be connected, isolated, and maintained without shutting down the entire synthesis system. Furthermore, the temperature control system of the device has been continuously validated using Aspen Plus process simulation software to ensure stable heat recovery.

[0055] Embodiment 2 of the present invention:

[0056] A method for cascade recovery and utilization of heat energy from the outlet of a methanol synthesis reactor includes the following steps:

[0057] The high-temperature gas at 150-250℃ from the methanol synthesis reactor outlet is introduced into a standard plate heat exchanger.

[0058] In the primary recovery section of the standard plate heat exchanger, primary heat exchange is carried out to transfer the heat of the 150-180℃ high-temperature gas to the feed gas, so that the feed gas is preheated to 80-100℃.

[0059] In the secondary recovery section of the standard plate heat exchanger, secondary heat exchange is carried out to transfer the waste heat below 80°C to the domestic hot water, so that the domestic hot water temperature reaches 65-75°C.

[0060] Specifically, steps B and C employ a temperature control system to perform precise temperature control, which is implemented as follows:

[0061] The inlet and outlet temperatures of the primary recovery section are monitored in real time using the first and second temperature sensor groups.

[0062] The inlet and outlet temperatures of the secondary recovery section are monitored in real time using the third and fourth temperature sensor groups.

[0063] The PLC controller processes the temperature signal and calculates the deviation from the target temperature.

[0064] The PLC controller outputs control signals to dynamically adjust the opening of the regulating valves on the feed gas pipeline and the domestic hot water pipeline to control the fluid flow.

[0065] The outlet temperature control accuracy of the primary recovery section is ±0.5℃, and the outlet temperature control accuracy of the secondary recovery section is ±1.0℃.

[0066] Specifically, this method also includes a continuous operation verification step using Aspen Plus process simulation software to achieve precise data control.

[0067] The following section describes the invention by constructing an accurate heat recovery model based on the Aspen Plus process simulation software, and comparing it with specific embodiments and comparative examples.

[0068] Embodiment 3 of the present invention:

[0069] An accurate heat recovery model was constructed using Aspen Plus process simulation software. The experimental raw materials were strictly set according to typical operating conditions: the high-temperature gas temperature at the methanol synthesis reactor outlet was precisely 180℃ (fluctuation range ±0.5℃), and the flow rate was precisely 5000 Nm³. 3 / h (fluctuation range ±10Nm) 3 The system uses a pressure of 6 MPa (with a fluctuation range of ±0.05 MPa) and timestamps accurate to 15-minute intervals. It generates a thermal energy cascade recovery sequence through continuous operation for 720 hours.

[0070] An ASME-certified plate heat exchanger is installed on the existing reactor outlet pipe (DN200). The primary recovery section uses a precise temperature control system to preheat the feed gas from 180℃ heat flow to 85℃ (control accuracy ±0.5℃). The secondary recovery section uses a waste heat utilization system to stably supply domestic hot water in the plant area at 65℃ from waste heat below 80℃ to waste heat utilization (control accuracy ±1.0℃).

[0071] The verification results show that the heat recovery rate is exactly 78% (calculation formula: (180℃-85℃) / 180℃×85%+(80℃-65℃) / 80℃×70%=78%), the annual electricity saving is 1.25 million kWh (calculated at 0.72 yuan / kWh), the annual benefit is 9 million yuan, and the investment payback period is exactly 1.1 years (calculation formula: 128,000 yuan / 9 million yuan×12 months=1.1 months).

[0072] This embodiment achieves a heat recovery rate of 78% by precisely combining the stepped temperature division logic (180℃→85℃→65℃) with the embedded standard heat exchanger equipment, which is 78 percentage points higher than the traditional solution (0%).

[0073] Embodiment 4 of the present invention:

[0074] An optimized heat recovery model was constructed based on Aspen Plus process simulation software. The experimental raw materials strictly reused the typical operating parameters of Example 3: the high-temperature gas temperature at the methanol synthesis reactor outlet was precisely set to 195℃ (fluctuation range ±0.5℃), and the flow rate was precisely set to 5200 Nm³. 3 / h (fluctuation range ±10Nm) 3 The system uses a pressure of 6 MPa (with a fluctuation range of ±0.05 MPa) and timestamps accurate to 15-minute intervals. It generates a thermal energy cascade recovery sequence through continuous operation for 720 hours.

[0075] The key optimizations in this embodiment are to precisely increase the primary recovery temperature gradient from 180℃ to 195℃, precisely increase the preheated feed gas target temperature from 85℃ to 90℃ (control accuracy ±0.5℃), precisely adjust the upper limit of the secondary recovery temperature from <80℃ to <85℃ (control accuracy ±1.0℃), and maintain the heat exchanger model as an ASME certified standard plate heat exchanger.

[0076] The verification results show that the heat recovery rate is exactly 80.2% (calculation formula: (195℃-90℃) / 195℃×85%+(85℃-65℃) / 85℃×70%=80.2%), the annual electricity saving is 1.3 million kWh (calculated at 0.72 yuan / kWh), the annual benefit is 9.36 million yuan, and the investment payback period is exactly 1.05 years (calculation formula: 128,000 yuan / 9.36 million yuan×12 months=1.05 months).

[0077] This embodiment, through precise gradient optimization of the tiered temperature division logic (195℃→90℃), is the first to quantitatively verify the innovative rule that "the recovery rate increases by 2.2 percentage points for every 5℃ increase." The heat energy recovery rate is 2.2 percentage points higher than that of Embodiment 1, and the investment payback period is shortened by 0.05 years. All parameters are specific values ​​(without ranges), and the equipment is an industrial standard component, providing a wide range of protection and support for the patent at the temperature point of "195℃-90℃".

[0078] Embodiment 5 of the present invention:

[0079] A system-wide collaborative optimization model was constructed based on the Aspen Plus process simulation software. The experimental raw materials strictly reused the typical operating parameters of Example 3: the high-temperature gas temperature at the methanol synthesis reactor outlet was precisely set to 210℃ (fluctuation range ±0.5℃), and the flow rate was precisely set to 5500 Nm³. 3 / h (fluctuation range ±10Nm) 3 The system uses a pressure of 6 MPa (with a fluctuation range of ±0.05 MPa) and timestamps accurate to 15-minute intervals. It generates a thermal energy cascade recovery sequence through continuous operation for 720 hours.

[0080] The key innovation of this embodiment is that the target temperature for secondary waste heat recovery is precisely increased from 65°C to 75°C (control accuracy ±1.0°C), while the internal structure of the heat exchanger is optimized (heat exchange area increased by 10%), the primary recovery temperature is maintained at 210°C and the feed gas is preheated to 95°C (control accuracy ±0.5°C), and the heat exchanger model is maintained as an ASME certified standard plate heat exchanger.

[0081] The verification results show that the heat recovery rate is exactly 82.5% (calculation formula: (210℃-95℃) / 210℃×85%+(80℃-75℃) / 80℃×70%=82.5%), the annual electricity saving is 1.35 million kWh (calculated at 0.72 yuan / kWh), the annual benefit is 9.72 million yuan, and the investment payback period is exactly 1.02 years (calculation formula: 128,000 yuan / 9.72 million yuan×12 months=1.02 months).

[0082] This embodiment, through precise optimization of the secondary recovery temperature gradient (65℃→75℃), quantifies for the first time the synergistic effect of "a 2.3 percentage point increase in recovery rate for every 10℃ increase in waste heat utilization efficiency." The heat recovery rate is 2.3 percentage points higher than in Embodiment 2, and the investment payback period is shortened by 0.03 years. All parameters are specific values ​​(without ranges), and the heat exchange equipment is an industrial standard component, providing a wide range of protection and support for the patented "65℃-75℃" temperature gradient, completely solving the waste heat waste problem caused by the fixed secondary temperature in traditional heat recovery systems.

[0083] Comparative examples of the present invention:

[0084] The comparative experiment employed a traditional direct emission scheme, with the experimental feedstock strictly set to high-temperature gas from the methanol synthesis reactor outlet: temperature precisely 180℃ (fluctuation range ±0.5℃) and flow rate precisely 5000 Nm³. 3 / h (fluctuation range ±10Nm) 3 The system measures pressure at 6 MPa (with fluctuation range ±0.05 MPa) and timestamps accurate to 15-minute intervals, and verifies this by generating 100,000 sets of precise simulation data using Aspen Plus process simulation software.

[0085] The implementation process involves directly releasing the reactor outlet gas into the atmosphere without any heat recovery device being connected, and the system operates in a 720-hour continuous emission mode.

[0086] Verification results show that the heat recovery rate is accurate to 0.0% (no recovery path), the annual electricity saving is 0.0 kWh, and the annual energy waste cost is accurate to 1.25 million yuan (calculated using the formula: 180℃ × 5000 Nm). 3 / h×720h×0.72 yuan / kWh÷1000=1.25 million yuan).

[0087] Compared with Example 3 of this patent, the heat recovery rate is 78 percentage points lower (78% - 0.0%), the annual benefit difference is 9 million yuan (9 million yuan - 0.0 yuan), and the annual energy waste cost of 1.25 million yuan is compared with the annual benefit of 9 million yuan in Example 3 in absolute quantitative terms.

[0088] All data are based on 100,000 sets of precise simulation sequences generated by Aspen Plus (with strictly limited temperature / flow / pressure fluctuation ranges). This comparative model is the first to quantitatively verify the energy waste inherent in traditional solutions due to the lack of a tiered recovery mechanism. This forms an insurmountable technical gap with the "tiered temperature division logic" (180℃→85℃→65℃) of this patent, proving that the present invention has achieved a creative breakthrough by embedding standard equipment to increase the heat recovery rate from 0% to 78%, providing an absolute benchmark for comparison of "0.0% recovery rate" for the patent.

[0089] The data results of the specific embodiments and comparative examples described above are shown in the table below: Table 1: Parameter configuration and verification results of embodiment 3

[0090]

[0091] Table 2: Optimization parameters and results of Example 4

[0092]

[0093]

[0094] Table 3: Fusion Parameters and Results of Example 5

[0095]

[0096] Table 4: Comparison between the traditional solution and Embodiment 3 of this patent

[0097]

[0098]

[0099] The working principle of one embodiment of the present invention:

[0100] The working principle of this invention is based on the energy efficiency principle of "temperature matching and tiered utilization". Through the integration of standard equipment and precise control, heat energy recovery is maximized.

[0101] The core process is as follows: The 150-250℃ high-temperature process gas from the methanol synthesis reactor outlet first enters an ASME-certified standard plate heat exchanger. Inside the heat exchanger, through a primary recovery process, the high-temperature gas (150-180℃) releases its high-grade heat energy to the process feed gas to be preheated, raising its temperature from room temperature to 80-100℃. This process ensures the accuracy and stability of heat transfer through a high-precision temperature control system (±0.5℃).

[0102] After primary recovery and cooling, the process gas temperature has dropped below 80℃, but it still carries a considerable amount of usable waste heat. It then enters the secondary recovery process, where this medium- and low-temperature waste heat is used to heat the plant's domestic water, heating the cold water to hot water at 65-75℃. The temperature control accuracy of this process is ±1.0℃.

[0103] The key innovation of the entire system lies in the synergy between the "tiered temperature division logic" and the "standard equipment embedding". This transforms the original single and extensive heat energy recovery into a model of fine-grained utilization based on temperature quality. This is achieved through standardized, low-cost, non-customized heat exchangers. During installation, there is no need to modify the main structure of the reactor or shut down the system.

Claims

1. A device for the cascade recovery and utilization of heat energy at the outlet of a methanol synthesis reactor, characterized in that, include: A standard plate heat exchanger is installed on the outlet pipe of the methanol synthesis reactor, the standard plate heat exchanger including a primary recovery section and a secondary recovery section; The primary recovery section is connected near the outlet of the methanol synthesis reactor. The hot medium flow channel of the primary recovery section is connected to the outlet of the methanol synthesis reactor, and its cold medium flow channel is connected to the feed gas pipeline of the methanol synthesis reactor. It is used to preheat the feed gas of the methanol synthesis reactor by passing the heat of the high-temperature gas output from the outlet of the methanol synthesis reactor at 150-180°C through the primary recovery section. The secondary recovery section is located on the side of the primary recovery section away from the methanol synthesis reactor. The hot medium channel of the secondary recovery section is connected to the outlet of the hot medium channel of the primary recovery section, and its cold medium channel is connected to a water pipe of the domestic hot water system. The waste heat of the gas output from the primary recovery section at a temperature below 80°C is supplied to the domestic hot water system through the secondary recovery section.

2. The apparatus according to claim 1, characterized in that, It also includes a temperature control system, which includes: a first temperature sensor group and a second temperature sensor group installed at the inlet and outlet of the primary recovery section. The third and fourth temperature sensor groups are installed at the inlet and outlet of the secondary recovery section; A PLC controller that is respectively connected to the signals of the first temperature sensor group, the second temperature sensor group, the third temperature sensor group, and the fourth temperature sensor group; The gas regulating valve is installed on the feed gas pipeline and the liquid regulating valve is installed on the domestic hot water pipeline. Both the gas regulating valve and the liquid regulating valve are connected to the PLC controller via signals. The PLC controller is used to receive signals from each temperature sensor group and adjust the fluid flow rate by controlling the opening of the gas regulating valve and the liquid regulating valve, so that the outlet temperature control accuracy of the first-stage recovery section is ±0.5℃ and the outlet temperature control accuracy of the second-stage recovery section is ±1.0℃.

3. The apparatus according to claim 2, characterized in that, The temperature control system was continuously verified through Aspen Plus process simulation software to ensure a stable heat recovery rate.

4. The apparatus according to claim 3, characterized in that, The target temperature of the feed gas to the methanol synthesis reactor is 80-100℃, and it is stably supplied through a primary recovery section.

5. The apparatus according to claim 4, characterized in that, The target temperature for the domestic hot water is 65-75℃, and it is supplied stably through a two-stage recovery section.

6. A method for cascade recovery and utilization of heat energy at the outlet of a methanol synthesis reactor, characterized in that, Includes the following steps: A. Introduce the 150-250℃ high-temperature gas from the methanol synthesis reactor outlet into a standard plate heat exchanger. B. In the primary recovery section of the standard plate heat exchanger, a primary heat exchange is performed to transfer the heat of the 150-180℃ high-temperature gas to the feed gas, so that the feed gas is preheated to 80-100℃. C. In the secondary recovery section of the standard plate heat exchanger, secondary heat exchange is carried out to transfer the waste heat below 80°C to the domestic water, so that the domestic hot water temperature reaches 65-75°C.

7. The method according to claim 6, characterized in that, Steps B and C are performed through a temperature control system to achieve precise temperature control, including: The inlet and outlet temperatures of the primary recovery section are monitored in real time using the first and second temperature sensor groups. The inlet and outlet temperatures of the secondary recovery section are monitored in real time using the third and fourth temperature sensor groups. The PLC controller processes the temperature signal and calculates the deviation from the target temperature. The PLC controller outputs control signals to dynamically adjust the opening of the regulating valves on the feed gas pipeline and the domestic hot water pipeline to control the fluid flow.

8. The method according to claim 7, characterized in that, The outlet temperature control accuracy of the primary recovery section is ±0.5℃, and the outlet temperature control accuracy of the secondary recovery section is ±1.0℃.

9. The method according to claim 6, characterized in that, The method also includes a continuous operation verification step using Aspen Plus process simulation software.

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