Nitrogen gas stripping residual pressure cold quantity combined recovery device of low-temperature methanol washing hydrogen sulfide concentration tower

Abstract

The utility model provides a kind of low-temperature methanol washing hydrogen sulfide concentration tower nitrogen gas stripping residual pressure cold quantity combined recovery device, it is related to energy recovery technical field, including low-pressure nitrogen pipe network, hydrogen sulfide concentration tower, adjusting unit and residual pressure cold quantity recovery device, adjusting unit includes throttling spare pipeline, throttling spare pipeline is equipped with flow regulating valve;Residual pressure cold quantity recovery device includes residual pressure cold quantity recovery pipeline, residual pressure cold quantity recovery pipeline is equipped with pressure regulating valve, expander and shell-and-tube heat exchanger, expander is connected with speed reduction drive mechanism, speed reduction drive mechanism is connected with generator, generator is connected with grid-connected cabinet, shell-and-tube heat exchanger is connected with hot material inlet pipe and hot material outlet pipe.The utility model utilizes expander to release nitrogen pressure difference potential energy, converts pressure energy into mechanical energy to drive generator to generate electricity, effectively recovers pipe network surplus pressure energy;Meanwhile, process hot material is pre-cooled by shell-and-tube heat exchanger, recycles and utilizes expansion cold, reduces the operation load of rear-end cooling equipment.

Description

Technical Field

[0001] This utility model relates to the field of energy recovery technology, and in particular to a combined recovery device for nitrogen stripping residual pressure and cooling capacity of a low-temperature methanol washing hydrogen sulfide concentration tower. Background Technology

[0002] Low-temperature methanol washing is a core process in the coal chemical industry for removing acidic gases such as hydrogen sulfide and carbon dioxide from syngas. The hydrogen sulfide concentration tower relies on low-pressure nitrogen stripping to enrich and concentrate these acidic gases. Currently, the commonly used field application employs 0.55MPa pipeline low-pressure nitrogen as the stripping gas source, directly throttling and reducing the pressure to the tower's rated operating pressure of 0.1MPa via a regulating valve. The pressure potential energy generated by the 0.45MPa pressure difference is entirely lost as throttling heat energy, resulting in extremely low energy utilization. Simultaneously, the nitrogen expands and its temperature drops sharply after throttling, possessing a significant amount of cryogenic cooling capacity. The existing process does not recover and utilize this cooling capacity, directly feeding it into the tower, resulting in a double waste of pressure energy and cryogenic cooling capacity, increasing the company's auxiliary media consumption and production operating costs. Currently, there is no mature device that can simultaneously achieve nitrogen residual pressure power generation and expansion cooling capacity recovery under these operating conditions. Utility Model Content

[0003] To address the aforementioned technical problems, this invention provides a combined recovery device for residual pressure cooling capacity from nitrogen stripping in a low-temperature methanol washing hydrogen sulfide concentration tower. This invention primarily utilizes an expander to replace a traditional throttling valve to release the nitrogen pressure differential potential energy, converting pressure energy into mechanical energy to drive a generator, eliminating throttling energy loss, and effectively recovering excess pressure energy from the pipeline network. Simultaneously, the expansion and cooling of nitrogen generates a large amount of low-temperature cooling capacity, which is used to pre-cool the process hot materials through a shell-and-tube heat exchanger, recovering and utilizing the expansion cooling capacity, and reducing the operating load on downstream cooling equipment. The technical means employed in this invention are as follows:

[0004] A combined recovery device for nitrogen stripping residual pressure and cold energy in a low-temperature methanol washing hydrogen sulfide concentration tower includes: a low-pressure nitrogen pipeline network, a hydrogen sulfide concentration tower, and a regulating unit and a residual pressure and cold energy recovery device connected in parallel. One side of the regulating unit and the residual pressure and cold energy recovery device are connected to the low-pressure nitrogen pipeline network, and the other side is connected to the hydrogen sulfide concentration tower. The regulating unit includes a throttling backup pipeline, and the throttling backup pipeline is equipped with a flow regulating valve; The residual pressure cold energy recovery device includes a residual pressure cold energy recovery pipeline. Along the airflow direction, a pressure regulating valve, an expander, and a shell-and-tube heat exchanger are sequentially arranged on the residual pressure cold energy recovery pipeline. The pressure regulating valve is located between the inlet side of the expander and the low-pressure nitrogen pipeline network. The shell-and-tube heat exchanger is located between the outlet side of the expander and the hydrogen sulfide concentration tower. The power end of the expander is connected to a reduction gear transmission mechanism, which is connected to a generator. The generator is connected to a grid-connected cabinet. The top and bottom of the shell-and-tube heat exchanger are respectively connected to a hot material inlet pipe and a hot material outlet pipe.

[0005] Furthermore, the expander is a low-temperature turbine expander with an inlet pressure range of 0.5MPa to 0.6MPa and an outlet pressure range of 0.08MPa to 0.12MPa.

[0006] Furthermore, a nitrogen temperature measuring point is provided on the pipeline connected to the outlet of the expander.

[0007] Furthermore, a temperature detection instrument is installed at the nitrogen temperature measuring point.

[0008] Furthermore, the hot material outlet pipe is equipped with a hot material temperature measuring point.

[0009] Furthermore, the temperature measuring point of the hot material is equipped with a temperature detection instrument.

[0010] Compared with the prior art, the present invention has the following advantages: 1. The low-temperature methanol washing hydrogen sulfide concentration tower nitrogen stripping residual pressure and cooling energy recovery device provided by this utility model uses a low-temperature turbine expander to replace the traditional throttling valve to release nitrogen pressure difference potential energy, converting pressure energy into mechanical energy to drive generator to generate electricity, eliminating throttling energy loss, and effectively recovering excess pressure energy from the pipeline network.

[0011] 2. The low-temperature methanol washing hydrogen sulfide concentration tower nitrogen stripping residual pressure cooling capacity combined recovery device provided by this utility model generates a large amount of low-temperature cooling capacity by expanding and cooling nitrogen. The process hot material is pre-cooled and cooled through shell and tube heat exchanger, and the expansion cooling capacity is recovered and utilized to reduce the operating load of downstream cooling equipment.

[0012] 3. The low-temperature methanol washing hydrogen sulfide concentration tower nitrogen stripping residual pressure cooling capacity combined recovery device provided by this utility model has a compact overall structure, is easy to install and modify, is compatible with the existing industrial plant site layout, has significant energy-saving effect, and has a wide range of applications.

[0013] Based on the above reasons, this utility model can be widely promoted in fields such as nitrogen residual pressure power generation and expansion cold energy recovery in low-temperature methanol washing processes. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a schematic diagram of the structure of the device of this utility model.

[0016] In the diagram: 1. Low-pressure nitrogen pipeline; 2. Flow regulating valve; 3. Pressure regulating valve; 4. Expander; 5. Reduction transmission mechanism; 6. Generator; 7. Grid connection cabinet; 8. Shell and tube heat exchanger; 9. Hot material inlet pipe; 10. Hot material outlet pipe; 11. Nitrogen temperature measuring point; 12. Hot material temperature measuring point; 13. Hydrogen sulfide concentration tower. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0018] To address the technical problems of severe energy waste and inability to recover cold energy in traditional nitrogen stripping processes, this invention provides a combined recovery device for residual pressure and cold energy from nitrogen stripping in a low-temperature methanol washing hydrogen sulfide concentration tower. This device achieves dual energy-saving effects of pressure energy power generation recovery and expansion cold energy heat exchange utilization, while retaining the original backup process to ensure continuous and stable production of the chemical plant.

[0019] This utility model discloses a combined recovery device for nitrogen stripping residual pressure and cold energy in a low-temperature methanol washing hydrogen sulfide concentration tower, comprising a low-pressure nitrogen pipeline network 1, a hydrogen sulfide concentration tower 13, and a regulating unit and a residual pressure and cold energy recovery device connected in parallel. One side of the regulating unit and the residual pressure and cold energy recovery device are connected to the low-pressure nitrogen pipeline network 1, and the other side is connected to the hydrogen sulfide concentration tower 13.

[0020] Two parallel nitrogen delivery pipelines are connected between the low-pressure nitrogen pipeline network 1 and the hydrogen sulfide concentration tower 13. The two nitrogen delivery pipelines are a throttling standby pipeline and a residual pressure cold energy recovery pipeline, respectively. A flow regulating valve 2 is installed on the throttling standby pipeline along the airflow direction. The throttling standby pipeline and the flow regulating valve 2 constitute a regulating unit.

[0021] The residual pressure and cold energy recovery device includes a residual pressure and cold energy recovery pipeline. Along the airflow direction, a pressure regulating valve 3 and an expander 4 are sequentially installed on the residual pressure and cold energy recovery pipeline. The power end of the expander 4 is connected to a reduction gear transmission mechanism 5, which is connected to a generator 6. The generator 6 is connected to a grid-connected cabinet 7, which is connected to the plant's power grid. The outlet of the expander 4 is connected to the nitrogen inlet of a shell-and-tube heat exchanger 8 through a pipeline. The nitrogen outlet of the shell-and-tube heat exchanger 8 is connected to the inlet of a hydrogen sulfide concentration tower 13 through a pipeline. The top and bottom of the shell-and-tube heat exchanger 8 are respectively connected to a hot material inlet pipe 9 and a hot material outlet pipe 10. A nitrogen temperature measuring point 11 is installed on the pipeline connected to the outlet of the expander 4, and a hot material temperature measuring point 12 is installed on the hot material outlet pipe 10.

[0022] Expander 4 adopts an existing low-temperature turbine expander with an inlet pressure range of 0.5MPa~0.6MPa (the inlet pressure is determined by the low-pressure nitrogen pipeline 1) and an outlet pressure range of 0.08MPa~0.12MPa (the outlet pressure is determined by the hydrogen sulfide concentration tower 13), matching the on-site pipeline network and tower operating pressure parameters.

[0023] Temperature sensors are installed at 11 nitrogen temperature measurement points to monitor the nitrogen outlet temperature, specifically the temperature of the nitrogen after expansion and work. Monitoring this temperature allows us to determine how many degrees Celsius the nitrogen temperature drops after expansion; the lower the temperature drop, the more cooling capacity is provided, thus offering more cooling to the hot materials in the process.

[0024] A temperature measuring instrument for monitoring the medium temperature is installed at the hot material temperature measuring point 12 on the hot material outlet pipe 10, that is, monitoring the temperature of the process hot material after heat exchange. Based on the monitored temperature of the nitrogen gas after expansion and work, the flow rate of the process hot material is adjusted to maintain the temperature of the process hot material after heat exchange, so that the downstream existing equipment can adjust the heat exchange conditions according to this temperature change.

[0025] The aforementioned temperature detection instrument can be an existing integrated temperature transmitter with an explosion-proof rating of ExiaIICT4.

[0026] All valves on the two parallel nitrogen delivery pipelines (i.e., flow control valve 2 and pressure control valve 3) are remotely controlled pneumatic shut-off valves. Both flow control valve 2 and pressure control valve 3 can be conventional instrument control valves. Both flow control valve 2 and pressure control valve 3 are safety-type on / off valves powered by instrument air and remotely controlled by electrical signals from the field control room, enabling rapid opening / closing over a distance. In other words, flow control valve 2 and pressure control valve 3 can be connected to the existing control room on site for remote opening and closing, eliminating the need for manual operation on-site.

[0027] The temperature of the heat exchanged material can be controlled by adjusting the expansion pressure and nitrogen expansion flow rate of the expander 4. The amount of cooling capacity can be adjusted by changing the outlet pressure and flow rate of the expander. The larger the expansion ratio, the greater the temperature drop and the stronger the cooling capacity; the larger the flow rate, the more heat is removed per unit time and the stronger the cooling capacity. 1) Expansion pressure (expander outlet pressure) control range: (1) Control target: expander outlet pressure 0.08~0.12MPa; (2) Normal stable working condition: 0.1MPa; (3) During deep cooling: can be reduced to 0.08MPa; (4) When increasing the material temperature: can be increased to 0.12MPa. 2) Nitrogen expansion flow rate control range: (1) Control target: design flow rate range 15000~25000Nm 3 / h; (2) During deep cooling: 20000~25000Nm 3 / h; (3) Reduce cooling: 15000~20000Nm 3 / h. The outlet temperature of the process hot material after heat exchange is stably controlled at 5-10℃ to meet the feed temperature requirements of subsequent processes.

[0028] The reduction transmission mechanism 5 is a mechanical structure that converts high speed to low speed while increasing torque. It can adopt existing structural forms and mainly includes a housing, a high-speed shaft, a low-speed shaft, a gear structure, bearings, and a coupling. The gear structure is placed inside the housing. The high-speed shaft is rotatably connected to the housing through bearings. One end of the high-speed shaft is connected to the power end of the expander 4 through a coupling, and the other end is connected to the gear structure. The low-speed shaft is rotatably connected to the housing through bearings. One end of the low-speed shaft is connected to the gear structure, and the other end is connected to the generator 6 through a coupling.

[0029] The low-pressure nitrogen pipeline 1 and the hydrogen sulfide concentration tower 13 are existing equipment on site. The generator 6, grid connection cabinet 7, and shell-and-tube heat exchanger 8 can all adopt existing structural forms, and the hot material inlet pipe 9 and hot material outlet pipe 10 can adopt existing pipeline structures.

[0030] This invention utilizes a cryogenic turbine expander to replace the traditional throttling valve, releasing the pressure differential potential energy of nitrogen gas. This pressure energy is converted into mechanical energy to drive a generator, eliminating energy loss from throttling and effectively recovering excess pressure energy from the pipeline network. The expansion and cooling of nitrogen gas generates a large amount of cryogenic cooling energy, which is used to pre-cool process materials through a shell-and-tube heat exchanger, recovering and utilizing the expansion cooling energy and reducing the operating load on downstream cooling equipment. The overall structure is compact, easy to install and modify, adaptable to existing industrial plant layouts, and offers significant energy savings with a wide range of applications.

[0031] The working principle of this utility model: Under normal production and energy-saving operation, close the flow regulating valve 2 on the throttling standby pipeline and open the pressure regulating valve 3 on the residual pressure and cold energy recovery pipeline. 0.55MPa low-pressure nitrogen flows out from the low-pressure nitrogen pipeline 1 and enters the expander 4 for adiabatic expansion. The nitrogen pressure is reduced to 0.1MPa to match the operating pressure inside the hydrogen sulfide concentration tower 13. During the expansion process, the expander 4 is driven to operate, and the generator 6 is driven by the reduction transmission mechanism 5 to achieve grid-connected power generation and complete the recovery of residual pressure energy. After the nitrogen expands and does work, its own temperature drops significantly. The low-temperature nitrogen enters the shell-and-tube heat exchanger 8 and exchanges heat in the opposite direction with the high-temperature process hot material fed from the hot material inlet pipe 9. The low-temperature nitrogen releases cold energy to cool the process hot material. After the heat exchange is completed, the nitrogen temperature rises and is finally smoothly fed into the hydrogen sulfide concentration tower 13 to complete the gas stripping operation. The process hot material after heat exchange and cooling is transported to the next process through the hot material outlet pipe 10 (the outlet temperature of the process hot material after heat exchange is controlled within the design index range to meet the requirements of the subsequent process for the feed temperature). During operation, the heat exchange condition is monitored in real time by temperature detection instruments. The nitrogen flow rate can be adjusted according to the temperature requirements of the process hot materials to control the cold energy recovery efficiency and meet the actual production process indicators on site. When the process hot materials require a low temperature, the nitrogen flow rate is increased and the operating pressure of the hydrogen sulfide concentration tower is reduced (the outlet pressure of the expander is correspondingly reduced), resulting in a larger cooling capacity; conversely, a smaller cooling capacity can increase the temperature of the process hot materials.

[0032] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although the 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 or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.

Claims

1. A combined recovery device for nitrogen stripping residual pressure and cooling capacity of a low-temperature methanol washing hydrogen sulfide concentration tower, characterized in that, include: The low-pressure nitrogen pipeline (1), the hydrogen sulfide concentration tower (13), and the regulating unit and the residual pressure cold energy recovery device are connected in parallel. One side of the regulating unit and the residual pressure cold energy recovery device are connected to the low-pressure nitrogen pipeline (1), and the other side is connected to the hydrogen sulfide concentration tower (13). The regulating unit includes a throttling backup pipeline, and the throttling backup pipeline is equipped with a flow regulating valve (2). The residual pressure cold energy recovery device includes a residual pressure cold energy recovery pipeline. A pressure regulating valve (3), an expander (4), and a shell-and-tube heat exchanger (8) are sequentially arranged along the airflow direction on the residual pressure cold energy recovery pipeline. The pressure regulating valve (3) is located between the air inlet side of the expander (4) and the low-pressure nitrogen pipeline (1). The shell-and-tube heat exchanger (8) is located between the air outlet side of the expander (4) and the hydrogen sulfide concentration tower (13). The power end of the expander (4) is connected to a reduction transmission mechanism (5). The reduction transmission mechanism (5) is connected to a generator (6). The generator (6) is connected to a grid-connected cabinet (7). The top and bottom of the shell-and-tube heat exchanger (8) are respectively connected to a hot material inlet pipe (9) and a hot material outlet pipe (10).

2. The low-temperature methanol washing hydrogen sulfide concentration tower nitrogen stripping residual pressure cooling capacity combined recovery device according to claim 1, characterized in that, The expander (4) is a low-temperature turbine expander with an inlet pressure range of 0.5MPa to 0.6MPa and an outlet pressure range of 0.08MPa to 0.12MPa.

3. The low-temperature methanol washing hydrogen sulfide concentration tower nitrogen stripping residual pressure cooling capacity combined recovery device according to claim 1, characterized in that, The outlet of the expander (4) is connected to a nitrogen temperature measuring point (11).

4. The low-temperature methanol washing hydrogen sulfide concentration tower nitrogen stripping residual pressure cooling capacity combined recovery device according to claim 3, characterized in that, A temperature detection instrument is installed at the nitrogen temperature measuring point (11).

5. The low-temperature methanol washing hydrogen sulfide concentration tower nitrogen stripping residual pressure cooling capacity combined recovery device according to claim 1, characterized in that, The hot material outlet pipe (10) is equipped with a hot material temperature measuring point (12).

6. The low-temperature methanol washing hydrogen sulfide concentration tower nitrogen stripping residual pressure cooling capacity combined recovery device according to claim 5, characterized in that, Temperature measuring instruments are installed at the temperature measuring point (12) of the hot material.

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