A safety protection system for industrial oxygen production

Abstract

The present invention provides a safety protection system for industrial oxygen production, which includes a fractionating tower, a nitrogen delivery pipeline, and a liquid oxygen delivery pipeline. The pipeline pressure of the nitrogen delivery pipeline is less than that of the liquid oxygen delivery pipeline. The nitrogen delivery pipeline and the liquid oxygen delivery pipeline are laid in parallel, and a nitrogen compressor is provided at the end of the nitrogen delivery pipeline; a number of safety stop valves are provided at the intermittent positions of the liquid oxygen delivery pipeline, and a set of anti-leakage safety protection microcirculation pipelines is provided between two adjacent safety stop valves; through local microcirculation, the problem of liquid oxygen leakage caused by pressure is alleviated, so that the dangerous liquid oxygen loses pressure and mixes with nitrogen to become a gas with a low oxygen content again, eliminating the explosion risk caused by too long leakage time.

Description

Technical Field

[0001] The present invention relates to the field of industrial oxygen production, and specifically, to a safety protection system for industrial oxygen production. Background Art

[0002] The currently used oxygen production technologies respectively include: electrolytic oxygen production method, separation of liquid air method, molecular sieve oxygen production method, and membrane separation method.

[0003] Among them, the electrolytic oxygen production method mainly uses electric energy to decompose water into oxygen and hydrogen. The equipment used is simple, but the energy consumption is too high, and it is only limited to laboratory use; the molecular sieve oxygen production method uses the property that nitrogen molecules are larger than oxygen molecules to screen out oxygen molecules from the air, thereby realizing the separation of oxygen. However, considering its small scale and low efficiency, it is generally used in single application environments, such as hospital and home oxygen production requirements, and there are also a small number of applications in the metallurgical industry; the membrane separation method uses a thin film to screen out oxygen, and the principle is similar to the molecular sieve oxygen production method, with limited scale and efficiency; the separation of liquid air method uses the difference in the boiling points of nitrogen (-196 degrees Celsius) and oxygen (-183 degrees Celsius) in the air to evaporate nitrogen and only retain liquid oxygen. Because it mainly uses large-scale equipment, the production efficiency is relatively high, and it is suitable for industrial production.

[0004] Currently, industrial oxygen production mainly uses the separation of liquid air method. Because of its high degree of scalability, high efficiency, and low cost, it is the main form of traditional oxygen production methods. However, due to factors such as high requirements for preparation temperature and pressure, the production safety requirements are extremely high, and the main cost of industrial applications is also concentrated in the procurement of safety protection equipment.

[0005] In the production process of liquid separation oxygen production, several key safety problems are relatively prominent. One is the problem of pipeline leakage or valve leakage in some high-pressure oxygen transmission pipelines. The current mainstream form is to adopt real-time monitoring. When it is detected that there is a leakage in the valve or pipeline, the upstream and downstream valves are immediately shut down to cut off the oxygen transmission process to avoid safety problems such as explosion. However, the oxygen transmission pipelines in industrial production are relatively thick, and the oxygen transmission is mainly in the form of liquid oxygen with high pressure. Even if shut down, it still takes a long time to wait for the leakage to discharge and release the pressure, and the danger is still relatively high. For example, if a local explosion occurs during the pressure release process, the explosion range will still exceed the cut-off area, triggering a chain explosion in the surrounding area.

[0006] Second, regarding the air separation part in the oxygen production process, due to insufficient filtration before the air separation device, some combustible gases, especially acetylene, are mixed into the finished liquid oxygen. As the pressure increases, acetylene accumulates into a solid state in the liquid oxygen. During the transportation process through the pipeline, friction between the pipeline and the solid causes heat generation and explosion. The reason is that acetylene is difficult to filter out during the pre-cooling and filtration stage. In a system mainly using liquid oxygen transportation, the enrichment of acetylene is relatively dangerous, and there is currently no technology for separating acetylene in liquid oxygen.

[0007] To solve the above existing problems, people have been seeking an ideal technical solution. Summary of the Invention

[0008] The purpose of the present invention is to address the deficiencies of the prior art and thus provide a safety protection system for industrial oxygen production that reduces the safety risks caused by liquid oxygen leakage, shortens the liquid oxygen discharge time, reduces the explosion risk, and extracts acetylene-enriched substances.

[0009] To achieve the above purpose, the technical solution adopted by the present invention is: a safety protection system for industrial oxygen production, including a fractionating tower, a nitrogen transportation pipeline, and a liquid oxygen transportation pipeline. The pipeline pressure of the nitrogen transportation pipeline is less than that of the liquid oxygen transportation pipeline. The nitrogen transportation pipeline and the liquid oxygen transportation pipeline are laid in parallel, and a nitrogen compressor is provided at the end of the nitrogen transportation pipeline;

[0010] A number of safety stop valves are provided at the intermittent positions of the liquid oxygen transportation pipeline, and a set of anti-leakage safety protection microcirculation pipelines are provided between two adjacent safety stop valves;

[0011] The anti-leakage safety protection microcirculation pipeline includes a first liquid oxygen three-way valve, a second liquid oxygen three-way valve, a first nitrogen three-way valve, a second nitrogen three-way valve, a third nitrogen three-way valve, a first circulation pipeline, a second circulation pipeline, and an evacuation pipeline. The first liquid oxygen three-way valve and the second liquid oxygen three-way valve are respectively provided inside two adjacent safety stop valves in the liquid oxygen transportation pipeline. The first nitrogen three-way valve and the second nitrogen three-way valve are provided on the nitrogen transportation pipeline and correspond to the positions of the first liquid oxygen three-way valve and the second liquid oxygen three-way valve;

[0012] The first liquid oxygen three-way valve and the first nitrogen three-way valve are connected through the first circulation pipeline. The second liquid oxygen three-way valve and the second nitrogen three-way valve are connected through the second circulation pipeline. The third nitrogen three-way valve is installed on the nitrogen transportation pipeline and is located at the midpoint between the first nitrogen three-way valve and the second nitrogen three-way valve. The third nitrogen three-way valve is connected to the evacuation pipeline;

[0013] A circulation pump is installed on the first circulation pipeline or the second circulation pipeline, and an evacuation pump is installed on the evacuation pipeline.

[0014] Preferably, the first liquid oxygen three-way valve, the second liquid oxygen three-way valve, the first nitrogen three-way valve, the second nitrogen three-way valve, the third nitrogen three-way valve and the safety stop valve are all electrically controlled valves. The first liquid oxygen three-way valve, the second liquid oxygen three-way valve, the first nitrogen three-way valve, the second nitrogen three-way valve, the third nitrogen three-way valve and the safety stop valve are associated and controlled by a controller, and the circulation pump and the evacuation pump are controlled by the controller to open and close.

[0015] Preferably, the working sequence of each valve is as follows: the safety stop valve is shut down, triggering the main road inlet of the first liquid oxygen three-way valve to be shut down and the branch road to be conducted, the main road outlet of the second liquid oxygen three-way valve to be stopped and the branch road to be conducted, the main road inlet of the first nitrogen three-way valve to be shut down and the branch road to be conducted, the main road outlet of the second nitrogen three-way valve to be stopped and the branch road to be conducted. The first circulation pipeline, the second circulation pipeline, the nitrogen delivery pipeline and the liquid oxygen delivery pipeline form a microcirculation pipeline. The circulation pump is started. After circulating for a period of time, the evacuation pump and the three-way of the third nitrogen three-way valve are conducted to discharge the mixed gas.

[0016] Preferably, the evacuation pump is a vacuum pump.

[0017] Preferably, a number of acetylene collectors connected in series are installed in the liquid oxygen delivery pipeline at the outlet of the fractionating column. The acetylene collector includes a pipe body, a fixing ring arranged in the pipe body, a filter screen installed in the fixing ring, a spoiler fan blade installed at the front end of the filter screen, and a rotating shaft for the spoiler fan blade to rotate. Both ends of the rotating shaft are fixed on the fixing ring.

[0018] Preferably, the diameter of the pipe body of the acetylene collector is larger than the diameter of the liquid oxygen delivery pipeline.

[0019] Preferably, the filter screen is a polymer acetylene adsorption screen.

[0020] Preferably, the fixing ring, the spoiler fan blade and the rotating shaft are all made of inert wear-resistant materials.

[0021] Preferably, the number of the acetylene collectors is at least two sets.

[0022] Preferably, a pipeline knot or a valve is arranged in the liquid oxygen delivery pipeline between the safety stop valves.

[0023] The present invention has outstanding substantive features and remarkable progress compared with the prior art. Specifically, the present invention has the following advantages:

[0024] 1. Design the nitrogen delivery pipeline as a gas delivery pipeline, and then compress it to form liquid nitrogen in the terminal area. Thus, the air pressure in the nitrogen delivery pipeline can be maintained at a low pressure. At the same time, parallel the nitrogen delivery pipeline with the liquid oxygen delivery pipeline and design a microcirculation pipeline. When a leak occurs at a certain point in the liquid oxygen delivery pipeline and triggers the safety stop valves at both ends to stop, the microcirculation pipeline works, conducting a partial nitrogen delivery pipeline and liquid oxygen delivery pipeline, enabling the pressure in the liquid oxygen delivery pipeline to be released in a relatively fast process. At the same time, due to the mixing of nitrogen and the vaporization of liquid oxygen, the gas is remixed to form a gas with a low oxygen content, significantly reducing the explosion risk. After circulating for a period of time, it can be directly discharged into the air, greatly reducing the harm to the air and ensuring safety.

[0025] 2. Design the evacuation pump as a vacuum pump, which only serves as an evacuation function after the cycle ends. After the maintenance is completed, start the vacuum pump again to evacuate the gas in the pipeline and maintain a certain vacuum degree. On the one hand, it can assist in monitoring whether there is still a leak in the pipeline, and on the other hand, it can exclude the existence of internal moist air, preventing pipeline corrosion during the waiting process for the oxygen production system to restart.

[0026] 3. Add a set of acetylene collection devices in the liquid oxygen delivery pipeline. Since no power module can be introduced into the pipeline, the power of the turbulent flow fan blades is used in cooperation with the flow of liquid oxygen to achieve passive turbulent flow, enabling the liquid oxygen to undergo slow turbulent flow while passing through the filter screen to adsorb the acetylene generated by enrichment, improving the purity of liquid oxygen and enhancing the safety of liquid oxygen. Description of the Drawings

[0027] Figure 1 It is a schematic diagram of the pipeline structure of the safety protection system for industrial oxygen production in the present invention.

[0028] Figure 2 It is a schematic diagram of the structure of the anti-leakage safety protection microcirculation pipeline in the case of valve leakage in the present invention.

[0029] Figure 3 It is a schematic diagram of the structure of the anti-leakage safety protection microcirculation pipeline in the case of pipeline leakage in the present invention.

[0030] Figure 4 It is a distribution diagram of the positions of the acetylene collectors in the present invention.

[0031] Figure 5 It is a schematic diagram of the internal structure of the acetylene collector in the present invention.

[0032] Figure 6 It is a cross-sectional view of the acetylene collector.

[0033] In the figure: 1. Fractionating tower; 2. Nitrogen delivery pipeline; 3. Liquid oxygen delivery pipeline; 4. Nitrogen compressor; 5. Safety stop valve; 6. First liquid oxygen three-way valve; 7. Second liquid oxygen three-way valve; 8. First nitrogen three-way valve; 9. Second nitrogen three-way valve; 10. Third nitrogen three-way valve; 11. First circulation pipeline; 12. Second circulation pipeline; 13. Drainage pipeline; 14. Circulation pump; 15. Drainage pump; 16. Acetylene collector; 161. Pipe body; 162. Fixed ring; 163. Filter screen; 164. Turbulence fan blade; 165. Rotating shaft. Detailed implementation mode

[0034] The technical solution of the present invention will be further described in detail below through specific implementation modes.

[0035] As Figures 1 - 3 shown, a safety protection system for industrial oxygen production includes a fractionating tower 1, a nitrogen delivery pipeline 2, and a liquid oxygen delivery pipeline 3. The pipeline pressure of the nitrogen delivery pipeline 2 is less than that of the liquid oxygen delivery pipeline 3. The nitrogen delivery pipeline 2 and the liquid oxygen delivery pipeline 3 are laid in parallel, and a nitrogen compressor 4 is provided at the end of the nitrogen delivery pipeline 2.

[0036] A number of safety stop valves 5 are provided at the discontinuous positions of the liquid oxygen delivery pipeline 3. A set of anti-leakage safety protection microcirculation pipelines is provided between two adjacent safety stop valves 5. The safety stop valve 5 is an original safety prevention and control valve in the oxygen production system. When a local leakage occurs, the safety stop valve 5 will be shut down in a timely manner through linkage control, thereby ensuring that no new liquid oxygen enters the intermediate pipeline. At the same time, due to the high pressure of liquid oxygen and the explosion safety accidents that are likely to occur at the leakage point, the traditional treatment method is to wait for the leakage to continue to achieve natural pressure reduction.

[0037] The anti-leakage safety protection microcirculation pipeline includes a first liquid oxygen three-way valve 6, a second liquid oxygen three-way valve 7, a first nitrogen three-way valve 8, a second nitrogen three-way valve 9, a third nitrogen three-way valve 10, a first circulation pipeline 11, a second circulation pipeline 12, and a drainage pipeline 13. The first liquid oxygen three-way valve 6 and the second liquid oxygen three-way valve 7 are respectively provided inside two adjacent safety stop valves 5 in the liquid oxygen delivery pipeline 2. The first nitrogen three-way valve 8 and the second nitrogen three-way valve 9 are provided on the nitrogen delivery pipeline 2 and correspond to the positions of the first liquid oxygen three-way valve 6 and the second liquid oxygen three-way valve 7.

[0038] The first liquid oxygen three-way valve 6 and the first nitrogen three-way valve 8 are connected through the first circulation pipeline 11. The second liquid oxygen three-way valve 7 and the second nitrogen three-way valve 9 are connected through the second circulation pipeline 12. The third nitrogen three-way valve 10 is installed on the nitrogen delivery pipeline 2 and is located at the midpoint between the first nitrogen three-way valve 8 and the second nitrogen three-way valve 9. The third nitrogen three-way valve 10 is connected to the drainage pipeline 13.

[0039] A circulation pump 14 is installed on the first circulation pipeline 11 or the second circulation pipeline 12 , and an exhaust pump 15 is installed on the exhaust pipeline 13 .

[0040] Among them, the first liquid oxygen three-way valve 6, the second liquid oxygen three-way valve 7, the first nitrogen three-way valve 8, the second nitrogen three-way valve 9, the third nitrogen three-way valve 10 and the safety stop valve 5 are all electrically controlled valves, and the first liquid oxygen three-way valve 6, the second liquid oxygen three-way valve 7, the first nitrogen three-way valve 8, the second nitrogen three-way valve 9, the third nitrogen three-way valve 10 and the safety stop valve 5 are associated and controlled by a controller, and the circulation pump 14 and the emptying pump 15 are controlled to be opened and closed by the controller, and the emptying pump 15 is a vacuum pump.

[0041] Description of the working principle after liquid oxygen pipeline leakage:

[0042] When leakage occurs at a pipeline node, the pipeline itself or a valve in the liquid oxygen delivery pipeline 3, the sensing device installed on the liquid oxygen delivery pipeline 3 will sound an alarm and close the safety stop valves 5 at both ends through the controller to prevent the problematic pipeline from continuing to work.

[0043] At the same time, the main inlet of the first liquid oxygen three-way valve 6 is closed and the branch is connected, the main outlet of the second liquid oxygen three-way valve 7 is blocked and the branch is connected, the main inlet of the first nitrogen three-way valve 8 is closed and the branch is connected, the main outlet of the second nitrogen three-way valve 9 is blocked and the branch is connected, the first circulation pipeline 11, the second circulation pipeline 12, the nitrogen delivery pipeline 2 and the liquid oxygen delivery pipeline 3 constitute a microcirculation pipeline, the circulation pump 14 is started, and the circulation pipeline continues to operate.

[0044] Since the pressure required by the nitrogen delivery pipeline 2 for transporting gaseous nitrogen is much lower than the pressure of the liquid oxygen delivery pipeline 3, after the circulation pipeline is opened, the liquid oxygen will flow into the nitrogen delivery pipeline 2 under the action of the pressure difference, thereby releasing the pressure of the liquid oxygen delivery pipeline 3. At the same time, due to the pressure of the liquid oxygen, it will vaporize and mix with the nitrogen in the process, thus re-forming a mixed gas containing a small amount of oxygen and a large amount of nitrogen. Although the oxygen content is usually slightly higher than that of natural air, it no longer has the characteristics of being flammable and explosive, thereby preventing the further development of safety accidents.

[0045] When the cycle reaches a certain equilibrium state, the exhaust valve 15 on the exhaust pipeline 13 is started to release the evenly mixed gas into the atmosphere, and the exhaust process will not cause harm to the environment.

[0046] In addition, if Figures 4 - 6As shown in the figure, in order to solve the technical problem that a small part of residual acetylene in liquid oxygen is prone to enrichment, the provided implementation method includes: two serially connected acetylene collectors 16 are installed in the liquid oxygen conveying pipeline 3 at the outlet of the fractionating tower 1. The acetylene collector 16 includes a pipe body 161, a fixing ring 162 arranged in the pipe body, a filter screen 163 installed in the fixing ring 162, a spoiler blade 164 installed at the front end of the filter screen 163, and a rotating shaft 165 for the spoiler blade 164 to rotate. Both ends of the rotating shaft 165 are fixed on the fixing ring 162. The pipe diameter of the acetylene collector 16 is larger than that of the liquid oxygen conveying pipeline 3. The filter screen 163 is a high-molecular acetylene adsorption net for adsorbing acetylene. The fixing ring 162, the spoiler blade 164, and the rotating shaft 165 are all made of inert wear-resistant materials.

[0047] The working principle of acetylene filtration is described as follows:

[0048] Since acetylene is prone to enrichment in liquid oxygen, and in the liquid separation method, the proportion of liquid oxygen produced is extremely small relative to the volume of nitrogen, the difficulty of acetylene enrichment is reduced, providing conditions for the removal of acetylene.

[0049] When the acetylene collector 16 is installed in the liquid oxygen conveying pipeline, when the liquid oxygen passes through, the pipe diameter increases and the flow state changes. At the same time, under the driving force of the flowing liquid oxygen, the spoiler blade 164 rotates around the rotating shaft 165, further disturbing the fluid, making the flow of the liquid oxygen relatively chaotic at this point, achieving full contact with the filter screen 163. During the contact process, acetylene is adsorbed, obtaining pure liquid oxygen. While achieving the purification of liquid oxygen, the harm brought by acetylene is avoided.

[0050] At the same time, it should be noted that since the flow rate of liquid oxygen is usually slow and the diameter expansion is limited, the interference of the spoiler on the properties of liquid oxygen can be ignored and will not cause the liquid oxygen to heat up or become unstable due to the spoiler problem.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that: it is still possible to modify the specific implementation manners of the present invention or perform equivalent replacements for some technical features; without departing from the spirit of the technical solutions of the present invention, they should all be covered within the scope of the technical solutions claimed by the present invention.

Claims

1. A safety protection system for industrial oxygen production, characterized in that: It includes a fractionating tower, a nitrogen delivery pipeline, and a liquid oxygen delivery pipeline. The pipeline pressure of the nitrogen delivery pipeline is less than that of the liquid oxygen delivery pipeline. The nitrogen delivery pipeline and the liquid oxygen delivery pipeline are laid in parallel, and a nitrogen compressor is provided at the end of the nitrogen delivery pipeline. A number of safety stop valves are provided at the intermittent positions of the liquid oxygen delivery pipeline, and a set of anti-leakage safety protection microcirculation pipelines are provided between two adjacent safety stop valves. The anti-leakage safety protection microcirculation pipeline includes a first liquid oxygen three-way valve, a second liquid oxygen three-way valve, a first nitrogen three-way valve, a second nitrogen three-way valve, a third nitrogen three-way valve, a first circulation pipeline, a second circulation pipeline, and an evacuation pipeline. The first liquid oxygen three-way valve and the second liquid oxygen three-way valve are respectively arranged inside two adjacent safety stop valves in the liquid oxygen delivery pipeline. The first nitrogen three-way valve and the second nitrogen three-way valve are arranged on the nitrogen delivery pipeline and at positions corresponding to the first liquid oxygen three-way valve and the second liquid oxygen three-way valve. The first liquid oxygen three-way valve and the first nitrogen three-way valve are connected through the first circulation pipeline. The second liquid oxygen three-way valve and the second nitrogen three-way valve are connected through the second circulation pipeline. The third nitrogen three-way valve is installed on the nitrogen delivery pipeline and at the centering position between the first nitrogen three-way valve and the second nitrogen three-way valve. The third nitrogen three-way valve is connected to the evacuation pipeline. A circulation pump is installed on the first circulation pipeline or the second circulation pipeline, and an evacuation pump is installed on the evacuation pipeline. The first liquid oxygen three-way valve, the second liquid oxygen three-way valve, the first nitrogen three-way valve, the second nitrogen three-way valve, the third nitrogen three-way valve, and the safety stop valve are all electrically controlled valves. The first liquid oxygen three-way valve, the second liquid oxygen three-way valve, the first nitrogen three-way valve, the second nitrogen three-way valve, the third nitrogen three-way valve, and the safety stop valve are associated and controlled by a controller. The circulation pump and the evacuation pump are controlled by the controller to open and close. The working sequence of each valve is as follows: when the safety stop valve shuts down, it triggers the main road inlet of the first liquid oxygen three-way valve to shut down and the branch road to conduct; the main road outlet of the second liquid oxygen three-way valve is stopped and the branch road conducts; the main road inlet of the first nitrogen three-way valve shuts down and the branch road conducts; the main road outlet of the second nitrogen three-way valve is stopped and the branch road conducts. The first circulation pipeline, the second circulation pipeline, the nitrogen delivery pipeline, and the liquid oxygen delivery pipeline form a microcirculation pipeline. The circulation pump starts. After circulating for a period of time, the evacuation pump and the three-way of the third nitrogen three-way valve conduct to discharge the mixed gas.

2. The safety protection system for industrial oxygen production according to claim 1, wherein: The evacuation pump is a vacuum pump.

3. The safety protection system for industrial oxygen production according to claim 1 or 2, characterized in that: A number of serially connected acetylene collectors are installed in the liquid oxygen delivery pipeline at the outlet of the fractionating tower. The acetylene collector includes a pipe body, a fixing ring arranged in the pipe body, a filter screen installed in the fixing ring, a spoiler fan blade installed in front of the filter screen, and a rotating shaft for the spoiler fan blade to rotate. The two ends of the rotating shaft are fixed on the fixing ring.

4. The safety protection system for industrial oxygen production according to claim 3, characterized in that: The diameter of the pipe body of the acetylene collector is larger than the diameter of the liquid oxygen delivery pipeline.

5. The safety protection system for industrial oxygen production according to claim 4, wherein: The filter screen is a polymer acetylene adsorption screen.

6. The safety protection system for industrial oxygen production according to claim 5, wherein: The materials of the fixing ring, the spoiler fan blade, and the rotating shaft are all inert wear-resistant materials.

7. The safety protection system for industrial oxygen production according to claim 6, characterized in that: The number of the acetylene collectors is at least two sets.

8. The safety protection system for industrial oxygen production according to claim 7, characterized in that: Pipeline nodules or valves are provided in the liquid oxygen delivery pipeline between the safety stop valves.

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