System for hydrogen production by means of reforming, deoxygenation and waste-gas emission reduction

Abstract

A system for hydrogen production by means of reforming, deoxygenation and waste-gas emission reduction, comprising: a deaerator having a first stream and a second stream which are arranged in a countercurrent manner, a first end of the first stream being a process condensate inlet, a second end of the first stream being a recycled water outlet, a first end of the second stream being a low-pressure steam inlet, and a second end of the second stream being a deoxygenated waste gas outlet; and a reformer comprising a radiation section, a transition section and a convection section which are connected in sequence, the transition section being provided with an injection port, a waste-gas discharge pipeline communicating the injection port with the deoxygenated waste gas outlet of the deaerator, and the convection section being provided with a flue gas outlet. In the present application, the total amount of harmful components discharged to the atmosphere by means of a natural-gas reforming device for hydrogen production can be reduced, and no additional waste-gas treatment unit is added, such that an increase in the construction cost of the device can be avoided.

Description

A waste gas emission reduction system for hydrogen production and deoxygenation Technical Field

[0001] The utility model belongs to the technical field of conversion hydrogen production, in particular to a conversion hydrogen production deoxygenation waste gas emission reduction system. Background Art

[0002] When existing large-scale industrial natural gas conversion hydrogen production plants are operating normally, deaerators are required to deoxygenate and remove impurities from the process condensate to reduce wastewater discharge. Due to the deaerator's operating principle, low-pressure steam must be continuously fed to the deaerator and discharged from the top of the deaerator. This steam removes dissolved impurities from the treated water and is then released into the atmosphere.

[0003] In the traditional process of natural gas steam reforming to produce hydrogen, trace organic by-products are generated and dissolved in the condensate due to reaction equilibrium. In addition, due to the high system pressure, a small amount of combustible gas is dissolved in the water. The by-product methanol and a small amount of combustible gas carried by the condensate in this process are directly discharged into the atmosphere. In the long run, this not only pollutes the environment, but also leads to waste of resources and increases process costs. Technical Solutions

[0004] In response to the above technical problems, the purpose of the present invention is to provide a waste gas emission reduction system for hydrogen production and deoxygenation, which can reduce the total amount of harmful components emitted into the atmosphere by the natural gas conversion hydrogen production device without adding additional waste gas treatment units, thereby avoiding an increase in the construction cost of the device.

[0005] In order to achieve the above purpose, the technical solutions adopted by this utility model are as follows:

[0006] A system for reducing waste gas emissions by converting hydrogen to produce hydrogen and removing oxygen, comprising:

[0007] The deaerator comprises a first stream and a second stream arranged in countercurrent, wherein the first end of the first stream is a process condensate inlet and the second end is a recovered water outlet; the first end of the second stream is a low-pressure steam inlet and the second end is a deoxygenated waste gas outlet;

[0008] The reformer comprises a radiation section, a transition section and a convection section connected in sequence. The transition section is provided with an injection port. An exhaust gas discharge pipeline is connected between the injection port and the deoxidized exhaust gas outlet of the deaerator. The convection section is provided with a flue gas outlet.

[0009] In some technical solutions, a condensate outlet is provided on the exhaust gas discharge pipeline, and the condensate outlet is connected to a water seal discharge pipeline.

[0010] In some technical solutions, there are multiple injection ports evenly distributed on the side wall of the transition section.

[0011] In some technical solutions, the deoxygenated waste gas outlet of the deaerator is connected to a three-way valve, a first outlet of the three-way valve is connected to the waste gas discharge pipeline, and a second outlet is connected to the waste gas venting pipeline.

[0012] Some technical solutions also include a steam flow pressure controller, which includes a regulating valve group, a pressure measuring element and a flow meter.

[0013] The regulating valve group includes a supply valve provided on the steam delivery pipeline connected to the low-pressure steam inlet, a discharge valve provided on the exhaust gas discharge pipeline, and a vent valve provided on the exhaust gas vent pipeline; the pressure measuring element is provided on the deaerator and is located at the outlet of the deoxidized exhaust gas; the flow meter is connected in series to the connecting pipeline between the outlet of the deoxidized exhaust gas and the inlet of the three-way valve;

[0014] The pressure measuring element is electrically connected to the supply valve and the vent valve respectively; the flow meter is electrically connected to the discharge valve and the vent valve respectively.

[0015] In some technical solutions, the steam flow pressure controller further includes a liquid level gauge provided at the outlet end of the recovered water of the deaerator, and the liquid level gauge is electrically connected to the discharge valve and the vent valve respectively.

[0016] In some technical solutions, the deaerator is provided with a liquid level alarm device, and the liquid level alarm device is electrically connected to the liquid level meter.

[0017] In some technical solutions, the steam flow pressure controller further includes a temperature measuring element disposed in the deaerator, and the temperature measuring element is electrically connected to the supply valve.

[0018] In some technical solutions, the pressure measuring element is electrically connected to the supply valve and the vent valve respectively through a pressure transmitter.

[0019] In some technical solutions, the flue gas outlet of the reformer is connected to the chimney. Beneficial effects

[0020] The above technical solution adopted by the present invention has at least the following beneficial effects:

[0021] 1. This utility model provides a hydrogen production and deoxidation waste gas emission reduction system. By directing the deoxidized waste gas from the deaerator into the transition section furnace of the reformer for combustion, the high temperature of the reformer decomposes organic matter, such as methanol, in the waste gas into carbon dioxide and water. A small amount of combustible gas reacts with oxygen in the reformer furnace waste gas to produce water and carbon dioxide. The reacted carbon dioxide and water are then discharged to a high point through the reformer chimney. This reduces trace amounts of organic harmful gases in the deaerator waste gas, ultimately reducing the total harmful substance emissions from the device. Furthermore, the high temperature of this furnace section minimizes the impact of the relatively low-temperature steam on subsequent heat exchange.

[0022] 2. The present invention further provides a system for reducing the emission of deoxygenated waste gas from hydrogen production by conversion. A water-sealed discharge line is provided on the waste gas discharge line to discharge condensate in the line without causing leakage of the deoxygenated waste gas.

[0023] 3. This utility model further provides a system for reducing the emission of deoxygenated waste gas from hydrogen production by reforming. The deoxygenated waste gas is fed into the reformer through multiple injection ports around the reformer, allowing the deoxygenated waste gas to be evenly mixed with the flue gas, thus avoiding the occurrence of localized low temperatures.

[0024] 4. This utility model further provides a system for reducing waste gas emissions from hydrogen production by deoxidation. By selectively controlling the flow rate and pressure of the deoxidizing steam and by implementing a safety interlocking control system, the system achieves a safe and stable deoxidation process and achieves excellent deoxidation results. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following is a brief introduction to the drawings and their markings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] FIG1 is a schematic structural diagram of a deoxygenation control unit according to an embodiment of the present invention;

[0027] FIG2 is a schematic structural diagram of an exhaust gas treatment unit according to an embodiment of the present invention. Modes for Carrying Out the Invention

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the specific implementation methods of the present invention will be described below with reference to the accompanying drawings. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings and other implementation methods can be obtained based on these drawings without inventive work.

[0029] To simplify the drawings, only the parts relevant to the utility model are schematically shown in each figure; they do not represent the actual structure of the product. Furthermore, to simplify the drawings and facilitate understanding, in some figures, only one of the components with the same structure or function is schematically depicted or labeled. In this document, "one" not only means "only one" but also "more than one."

[0030] It should be noted that, unless otherwise specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they can refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediary; and internal communication between two components. Those skilled in the art will understand the specific meanings of these terms in this utility model based on the specific circumstances.

[0031] This application considers the high reaction temperatures of the reformer in a hydrogen production unit, typically exceeding 800°C. The deaerator exhaust is routed to the reformer furnace. The high temperature of the reformer decomposes organic matter, such as methanol, into carbon dioxide and water. A small amount of combustible gas reacts with oxygen in the reformer exhaust to produce water and carbon dioxide. The resulting carbon dioxide and water are then discharged through the reformer's chimney to a high-point discharge point.

[0032] According to one embodiment of the present invention, it relates to a hydrogen production conversion and deoxygenation waste gas emission reduction system, which specifically includes a deoxygenation control unit and a waste gas treatment unit, wherein the deoxygenation control unit is used to control the safe and stable progress of the deoxygenation process, and the waste gas treatment unit is used to lead the deoxygenated waste gas to the furnace of the converter for full combustion and purification before discharge.

[0033] In the above embodiment, the deaerator control unit includes a deaerator and a steam flow pressure controller, the deaerator has a first stream and a second stream arranged in countercurrent, the first end of the first stream is the process condensate inlet, and the second end is the recovered water outlet; the first end of the second stream is the low-pressure steam inlet, and the second end is the deaerator exhaust gas outlet; wherein a steam delivery pipeline is connected between the low-pressure steam inlet and the steam source, the deaerator exhaust gas outlet is connected to a three-way valve, the first outlet of the three-way valve is connected to the exhaust gas discharge pipeline, and the second outlet is connected to the exhaust gas discharge pipeline. Gas venting pipeline; the steam flow pressure controller includes a regulating valve group, a pressure measuring element and a flow meter, the regulating valve group includes a supply valve arranged on the steam transmission pipeline, a discharge valve arranged on the exhaust gas discharge pipeline and a vent valve arranged on the exhaust gas venting pipeline; the pressure measuring element is arranged on the deaerator and is located at the outlet end of the deoxidized exhaust gas; the flow meter is connected in series to the connecting pipeline between the outlet of the deoxidized exhaust gas and the inlet of the three-way valve; wherein, the pressure measuring element is electrically connected to the supply valve and the vent valve respectively; the flow meter is electrically connected to the discharge valve and the vent valve respectively.

[0034] In a specific embodiment, the pressure measuring element is electrically connected to the supply valve and the vent valve respectively through a pressure transmitter.

[0035] In a preferred embodiment, the steam flow pressure controller also includes a liquid level gauge provided at the reclaimed water outlet end of the deaerator, and the liquid level gauge is electrically connected to the discharge valve and the vent valve respectively; preferably, the deaerator is also provided with a liquid level alarm device, and the liquid level alarm device is electrically connected to the liquid level gauge; in addition, a temperature measuring element is also provided in the deaerator, and the temperature measuring element is electrically connected to the supply valve.

[0036] The control logic of the steam flow and pressure controller is described in detail below:

[0037] Because steam delivery involves pressure and temperature control of the deaerator, this invention has developed a control scheme to support the new process. Inadequate steam flow and pressure control can lead to overpressure damage to the equipment or poor deoxidation performance. The supporting control logic includes layered control of the deoxidized steam flow and steam delivery pressure, selective control of steam flow and pressure, and safety interlock control. The relevant control logic is described below:

[0038] Under normal operating conditions, the discharge valve on the exhaust gas discharge line to the reformer is controlled by the flow rate of the flow meter on the top of the deaerator;

[0039] Under normal operating conditions, the vent valve on the exhaust gas vent line is controlled by the pressure of the deaerator top pressure transmitter and is closed under normal operating conditions. When the upper cut-off valve of the deaerator to reformer pipeline is interlocked and closed, the vent valve selection on the exhaust gas vent line is controlled by the deaerator top pressure and the exhaust steam flow signal.

[0040] When the deaerator liquid level is high, the vent valve control mode on the exhaust gas vent pipeline is set to manual, the valve is forced to fully open, and the valve control mode is set to automatic after the high liquid level alarm is lifted; when the deaerator liquid level is high, the discharge valve on the exhaust gas discharge pipeline is delayed for 15 minutes and the control mode is set to manual, the valve is forced to close, and the valve control mode is set to automatic after the high liquid level alarm is lifted.

[0041] The deaerator of this application is equipped with a tee at the top, which is divided into two outlets to the atmosphere and the converter respectively. Both pipelines are equipped with emergency vent valves and related controls. Under normal operating conditions, the exhaust gas from the top of the deaerator is sent to the converter for treatment and discharge, the vent shut-off valve is closed, and the exhaust gas shut-off valve is opened. Considering emergency conditions, such as overpressure in the deaerator, too high liquid level, excessive steam flow and other conditions where there are safety risks, the shut-off valve can be switched, the exhaust gas shut-off valve can be closed, and the vent shut-off valve can be opened to discharge the exhaust gas to the atmosphere in an emergency to protect the safety of the equipment and devices. After the process system returns to stability, it can be switched back to the normal operating process.

[0042] In the above embodiment, the waste gas treatment unit is provided with a converter, which includes a radiation section, a transition section and a convection section connected in sequence. The transition section is provided with an injection port, and the waste gas discharge pipeline connects the injection port and the deoxygenated waste gas outlet of the deaerator. The convection section is provided with a flue gas outlet, and the flue gas outlet is connected to the chimney.

[0043] In a preferred embodiment, the exhaust gas pipeline is equipped with a condensate outlet, which is connected to a water-seal discharge line. Before entering the reformer, the deoxygenated exhaust gas passes through the water-seal discharge line, where it condenses due to heat dissipation. The process then flows to the transition section of the reformer. This section has a high temperature, so the relatively low-temperature steam has minimal impact on subsequent heat exchange.

[0044] In another preferred embodiment, there are multiple injection ports evenly distributed on the side walls of the transition section. Specifically, they can be evenly distributed around the circumference of the side walls of the transition section, or multiple injection ports can be evenly set on both side walls of the transition section. This requires that steam is delivered to the converter through multiple injection ports around the converter, and can be evenly mixed with the flue gas to avoid local low temperatures.

[0045] The utility model can reduce the total amount of harmful components discharged into the atmosphere by a natural gas conversion hydrogen production device without adding an additional exhaust gas treatment unit, thereby avoiding an increase in device construction costs.

[0046] The above-described embodiments merely represent several implementation methods of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the scope of the present invention, and these modifications and improvements fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A system for reducing waste gas emissions by converting hydrogen to produce hydrogen and removing oxygen, characterized in that: include: A deaerator, comprising a first stream and a second stream arranged in countercurrent, wherein a first end of the first stream is a process condensate inlet, and a second end is a recovered water outlet; a first end of the second stream is a low-pressure steam inlet, and a second end is a deoxygenated waste gas outlet; The reformer comprises a radiation section, a transition section and a convection section which are connected in sequence. The transition section is provided with an injection port. An exhaust gas discharge pipeline is connected between the injection port and the deoxygenated exhaust gas outlet of the deaerator. The convection section is provided with a smoke outlet.

2. The waste gas emission reduction system for hydrogen production and deoxygenation according to claim 1 is characterized in that: The exhaust gas discharge pipeline is provided with a condensate outlet, and the condensate outlet is connected with a water seal discharge pipeline.

3. The waste gas emission reduction system for hydrogen production and deoxygenation according to claim 1 is characterized in that: The injection ports are located on the side wall of the transition section and are evenly distributed.

4. The waste gas emission reduction system for hydrogen production and deoxygenation according to claim 1, characterized in that: The deoxygenated waste gas outlet of the deaerator is connected to a three-way valve, a first outlet of the three-way valve is connected to the waste gas discharge pipeline, and a second outlet is connected to a waste gas venting pipeline.

5. The waste gas emission reduction system for hydrogen production and deoxygenation according to claim 4 is characterized in that: It also includes a steam flow pressure controller, which includes a regulating valve group, a pressure measuring element and a flow meter. The regulating valve group includes a supply valve arranged on the steam delivery pipeline connected to the low-pressure steam inlet, a discharge valve arranged on the exhaust gas discharge pipeline, and a vent valve arranged on the exhaust gas vent pipeline; the pressure measuring element is arranged on the deaerator and located at the outlet of the deoxygenated exhaust gas; the flow meter is connected in series to the connecting pipeline between the outlet of the deoxygenated exhaust gas and the inlet of the three-way valve; The pressure measuring element is electrically connected to the supply valve and the vent valve respectively; the flow meter is electrically connected to the discharge valve and the vent valve respectively.

6. The waste gas emission reduction system for hydrogen production and deoxygenation according to claim 5 is characterized in that: The steam flow pressure controller further comprises a liquid level gauge arranged at the outlet end of the recovered water of the deaerator, and the liquid level gauge is electrically connected to the discharge valve and the vent valve respectively.

7. The waste gas emission reduction system for hydrogen production and deoxygenation according to claim 6 is characterized in that: The deaerator is provided with a liquid level alarm device, and the liquid level alarm device is electrically connected to the liquid level meter.

8. The waste gas emission reduction system for hydrogen production and deoxygenation according to claim 5 is characterized in that: The steam flow pressure controller further comprises a temperature measuring element disposed in the deaerator, and the temperature measuring element is electrically connected to the supply valve.

9. The waste gas emission reduction system for hydrogen production and oxygen removal according to claim 5, characterized in that: The pressure measuring element is electrically connected to the supply valve and the vent valve respectively through a pressure transmitter.

10. The waste gas emission reduction system for hydrogen production and oxygen removal according to claim 1, characterized in that: The flue gas outlet of the reformer is communicated with the chimney.

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