System and method for safely emptying valve chamber of hydrogen-mixed natural gas pipeline
阅读说明:本技术 一种混氢天然气管道阀室安全放空系统及方法 (System and method for safely emptying valve chamber of hydrogen-mixed natural gas pipeline ) 是由 陈俊文 汤晓勇 郭成华 谌贵宇 郭艳林 李天雷 杨帆 施岱艳 陈静 李科 于 2019-09-29 设计创作,主要内容包括:本发明公开了一种混氢天然气管道阀室安全放空系统及方法,系统包括干线截断系统、放空及放空补偿系统和空气置换系统。本发明通过设置临时空气置换系统排尽初始放空时放空管道内空气,从本质上保障初始放空阶段的安全操作;采用放空速率补偿系统,防止放空中后期管道内压力降低而造成介质流速过小,进而引起放空管压力降低的问题;同时,设置阻火器进一步提高系统防回火性能。通过本发明,实现混氢天然气管道的阀室安全放空。本发明一方面省去了设置运行期隔离放空系统中空气进入的设施,另一方面通过设置严谨的置换和补偿放空功能,避免了混氢天然气在阀室泄放中的安全问题。(The invention discloses a system and a method for safely emptying a hydrogen-mixed natural gas pipeline valve chamber. According to the invention, the temporary air replacement system is arranged to exhaust air in the emptying pipeline during initial emptying, so that the safe operation of the initial emptying stage is guaranteed essentially; the emptying rate compensation system is adopted to prevent the problem that the pressure of the emptying pipe is reduced due to the fact that the medium flow velocity is too small because the pressure in the pipe is reduced in the middle and later periods of emptying; meanwhile, the flame arrester is arranged to further improve the anti-backfire performance of the system. By the aid of the method, the valve chamber of the hydrogen-mixed natural gas pipeline is safely emptied. On one hand, the invention omits a facility for isolating air from the emptying system during the operation period, and on the other hand, the safety problem of the mixed hydrogen natural gas in the valve chamber discharge is avoided by setting strict replacement and compensation emptying functions.)
1. The utility model provides a mix hydrogen natural gas line valve room safety unloading system which characterized in that: including trunk cut-off system, unloading and unloading compensating system and air replacement system, wherein:
the main line cut-off system comprises a main line pipeline and a cut-off ball valve arranged on the main line pipeline, a main line bypass is arranged at the upstream and downstream of the cut-off ball valve, bypass cut-off valves and pressure transmitters are arranged at the positions, close to the main line, of the two ends of the main line bypass, and the pressure transmitter is arranged on the main line bypass between the two bypass cut-off valves;
the emptying and emptying compensation system comprises a bypass external pipeline, a high-pressure branch pipe, an emptying junction, an emptying header pipe and an emptying torch which are sequentially connected with a main line bypass, wherein emptying block valves and flow-limiting pore plates or regulating valves are arranged on two branch pipelines of the high-pressure branch pipe;
the air replacement system comprises two replacement air injection branch pipes arranged on a main line bypass near the downstream of two bypass block valves, three replacement exhaust branch pipes arranged at the starting end and the tail end of a bypass external pipeline and an emptying header pipe, block valves arranged on the two replacement air injection branch pipes, and block valves and check valves arranged on the three replacement exhaust branch pipes.
2. The mixed hydrogen natural gas pipeline valve chamber safety venting system of claim 1, wherein: the main pipeline and the main bypass are made of carbon steel, the cut-off ball valve is an electric ball valve or a gas-liquid linkage ball valve, and the bypass cut-off valve is a manual control ball valve.
3. The mixed hydrogen natural gas pipeline valve chamber safety venting system of claim 1, wherein: the emptying manifold and the emptying header pipe are both made of stainless steel materials, and the emptying header pipe is buried underground and laid to an emptying torch.
4. The mixed hydrogen natural gas pipeline valve chamber safety venting system of claim 1, wherein: and the two ends of the emptying header pipe are respectively provided with a pi-shaped bend.
5. The mixed hydrogen natural gas pipeline valve chamber safety venting system of claim 1, wherein: and a flame arrester is arranged at the tail end of the emptying main pipe close to the emptying torch.
6. The mixed hydrogen natural gas pipeline valve chamber safety venting system of claim 1, wherein: and a flow transmitter is arranged on the emptying header pipe.
7. The mixed hydrogen natural gas pipeline valve chamber safety venting system of claim 1, wherein: the bottom of the emptying torch is connected with a torch cushion gas injection branch pipe, and a cut-off valve is arranged on the torch cushion gas injection branch pipe.
8. The mixed hydrogen natural gas pipeline valve chamber safety venting system of claim 7, wherein: the shut-off valve of the air displacement system is a double shut-off valve.
9. A safe emptying method for a hydrogen-mixed natural gas pipeline valve chamber is characterized by comprising the following steps: the method comprises the following steps:
step one, when a main line of a hydrogen-mixed natural gas pipeline needs to be overhauled, remotely closing main line cut-off ball valves adjacent to valve chambers at the upstream and downstream of the main line; or when the main line of the hydrogen-mixed natural gas pipeline leaks, the system automatically closes the main line cut-off ball valves close to the valve chamber at the upstream and the downstream of the main line where the leakage position is located; meanwhile, keeping both the two bypass block valves closed;
when the mixed hydrogen natural gas in an upstream trunk or a downstream trunk needs to be discharged through the valve chamber, a No. 1 movable nitrogen supply device is connected with a joint of a bypass gas injection branch pipe close to one side of the downstream or the upstream, the emptying cut-off valves on two branch pipelines of the emptying and emptying compensation system are opened, the four full cut-off valves arranged on a displacement exhaust branch pipe and a flare cushion gas injection branch pipe are kept closed, nitrogen is continuously injected for at least 10 minutes, and the air in the emptying pipeline is pushed to an emptying flare; simultaneously, three cut-off valves on the displacement exhaust branch pipe are respectively opened at intervals, and each cut-off valve is kept opened for at least 0.5 minute to ensure that air in the emptying pipeline is exhausted nearby; then closing three cut-off valves on the replacement exhaust branch pipe, continuously keeping nitrogen injection, simultaneously connecting an interface of the flare cushion gas injection branch pipe by using a No. 2 movable nitrogen supply device, opening the cut-off valves on the flare cushion gas injection branch pipe, introducing nitrogen, and pushing the air in the flare cushion region out of a flare outlet; finally, closing the emptying block valve on one branch pipeline;
step three, opening a bypass block valve at one side of a pipeline to be discharged, closing the No. 1 movable nitrogen supply device, feeding the mixed hydrogen natural gas into a venting system, limiting and reducing the pressure through a flow-limiting orifice plate or a regulating valve on one branch pipeline, and feeding the mixed hydrogen natural gas into a venting pipeline; closing the No. 2 movable nitrogen supply device; continuously igniting the torch head until the hydrogen-mixed natural gas at the outlet of the torch is discharged and continuously burning;
and step four, after the pressure of the upstream pipeline is reduced to 50%, opening a stop valve on the other branch pipeline, and increasing the discharge rate until the discharge is finished.
10. The method for safely venting a hydrogen-mixed natural gas pipeline valve chamber according to claim 9, wherein: in the nitrogen injection process, when the flow transmitter arranged on the emptying header pipe displays that the flow is too low, the emptying pipeline is overhauled to remove blockage.
Technical Field
The invention relates to a system and a method for safely emptying a hydrogen-mixed natural gas pipeline valve chamber.
Background
Hydrogen is one of the important development directions of new energy, compared with the traditional fossil fuel, the hydrogen has the remarkable advantages of high heat value, no environmental pollution of combustion products, wide sources and reproducibility, is called as future clean energy, and becomes a new way for solving increasingly severe energy and environmental problems in the future for human beings. The transportation of hydrogen is an important link for hydrogen energy utilization, and the adoption of a reliable pipeline transportation mode for connecting a hydrogen gas source with a target user is a key for optimizing energy consumption and promoting hydrogen energy utilization. Compared with a high-purity hydrogen pipeline (the hydrogen content is higher than 99%) which is directly paved on a natural gas main pipeline (used for long-distance output of a natural gas main pipeline after mixing) or a user, the hydrogen-mixed natural gas pipeline has the characteristics of flexible resource allocation and high pipeline utilization rate, an upstream hydrogen product can be mixed into an adjacent natural gas branch pipeline to reach the user or a natural gas main pipeline mixing station, remote transmission in the same pipe is realized, or methane hydrogen generated by ethane cracking is transmitted to the user or the natural gas main pipeline mixing station, and the long-distance relay transportation and utilization path of the hydrogen resource which is hot in the future becomes. However, hydrogen is prone to leakage and the explosion limit is wide (4% to 75%); meanwhile, spontaneous combustion (combustion) is likely to occur after the hydrogen is discharged, and the combustion mechanism mainly comprises diffusion spontaneous combustion, friction spontaneous combustion and ignition combustion, and the hydrogen is extremely easy to develop into the internal detonation or explosion of the pipeline. Further, the characteristics of the hydrogen-natural gas system are more complicated after blending natural gas in different proportions.
The emptying system of the mixed hydrogen natural gas conveying pipeline system is one of the cores of the safety guarantee system and is used for discharging media in the pipeline under the working conditions of overpressure, maintenance and the like. Compared with stations which can depend on large-scale relief facilities, such as the first station and the last station of the pipeline, the safety configuration problem of the emptying system of the valve chambers along the pipeline needs to comprehensively consider the problems of feasibility, safety, economy and the like. For a hydrogen-mixed natural gas system, in the initial discharge stage, diffusion spontaneous combustion without an ignition source caused by the fact that a large amount of media enter an emptying pipeline can occur, friction spontaneous combustion caused by severe friction between the media and the pipeline can also occur, and the media can be ignited by the outside to cause combustion near a pipe orifice when leaving an emptying vertical pipe; when the closed pipeline is burnt, deflagration or explosion is easily induced. At the same time, due to the combustion characteristics of the hydrogen, a flashback may occur in the vent line which is stronger than the natural gas bleed. Therefore, for a large station with better emptying depending conditions, the mixed hydrogen natural gas can be safely discharged through a torch system, but for the emptying system of the mixed hydrogen natural gas pipeline valve chamber, due to the relatively poorer depending conditions, safety and economic configuration research of the emptying system should be carried out, emptying safety is guaranteed, so that the blank reported in the prior art is made up, and the technical progress in the field is promoted.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides a system and a method for safely emptying a valve chamber of a mixed hydrogen natural gas pipeline, wherein a temporary air replacement system is arranged to exhaust air in an emptying pipeline during initial emptying, so that the safe operation in an initial emptying stage is guaranteed essentially; the emptying rate compensation system is adopted to prevent the problem that the pressure of the emptying pipe is reduced due to the fact that the medium flow velocity is too small because the pressure in the pipe is reduced in the middle and later periods of emptying; meanwhile, the flame arrester is arranged to further improve the anti-backfire performance of the system. By the aid of the method, the valve chamber of the hydrogen-mixed natural gas pipeline is safely emptied.
The technical scheme adopted by the invention is as follows: the utility model provides a mix hydrogen natural gas line valve room safety unloading system, includes that the trunk cuts off system, unloading and unloading compensating system and air replacement system, wherein:
the main line cut-off system comprises a main line pipeline and a cut-off ball valve arranged on the main line pipeline, a main line bypass is arranged at the upstream and downstream of the cut-off ball valve, bypass cut-off valves and pressure transmitters are arranged at the positions, close to the main line, of the two ends of the main line bypass, and the pressure transmitter is arranged on the main line bypass between the two bypass cut-off valves;
the emptying and emptying compensation system comprises a bypass external pipeline, a high-pressure branch pipe, an emptying junction, an emptying header pipe and an emptying torch which are sequentially connected with a main line bypass, wherein emptying block valves and flow-limiting pore plates or regulating valves are arranged on two branch pipelines of the high-pressure branch pipe;
the air replacement system comprises two replacement air injection branch pipes arranged on a main line bypass near the downstream of two bypass block valves, three replacement exhaust branch pipes arranged at the starting end and the tail end of a bypass external pipeline and an emptying header pipe, block valves arranged on the two replacement air injection branch pipes, and block valves and check valves arranged on the three replacement exhaust branch pipes.
The invention also provides a safe emptying method for the hydrogen-mixed natural gas pipeline valve chamber, which comprises the following steps:
step one, when a main line of a hydrogen-mixed natural gas pipeline needs to be overhauled, remotely closing main line cut-off ball valves adjacent to valve chambers at the upstream and downstream of the main line; or when the main line of the hydrogen-mixed natural gas pipeline leaks, the system automatically closes the main line cut-off ball valves close to the valve chamber at the upstream and the downstream of the main line where the leakage position is located; meanwhile, keeping both the two bypass block valves closed;
when the mixed hydrogen natural gas in an upstream trunk or a downstream trunk needs to be discharged through the valve chamber, a No. 1 movable nitrogen supply device is connected with a joint of a bypass gas injection branch pipe close to one side of the downstream or the upstream, the emptying cut-off valves on two branch pipelines of the emptying and emptying compensation system are opened, the four full cut-off valves arranged on a displacement exhaust branch pipe and a flare cushion gas injection branch pipe are kept closed, nitrogen is continuously injected for at least 10 minutes, and the air in the emptying pipeline is pushed to an emptying flare; simultaneously, three cut-off valves on the displacement exhaust branch pipe are respectively opened at intervals, and each cut-off valve is kept opened for at least 0.5 minute to ensure that air in the emptying pipeline is exhausted nearby; then closing three cut-off valves on the replacement exhaust branch pipe, continuously keeping nitrogen injection, simultaneously connecting an interface of the flare cushion gas injection branch pipe by using a No. 2 movable nitrogen supply device, opening the cut-off valves on the flare cushion gas injection branch pipe, introducing nitrogen, and pushing the air in the flare cushion region out of a flare outlet; finally, closing the emptying block valve on one branch pipeline;
step three, opening a bypass block valve at one side of a pipeline to be discharged, closing the No. 1 movable nitrogen supply device, feeding the mixed hydrogen natural gas into a venting system, limiting and reducing the pressure through a flow-limiting orifice plate or a regulating valve on one branch pipeline, and feeding the mixed hydrogen natural gas into a venting pipeline; closing the No. 2 movable nitrogen supply device; continuously igniting the torch head until the hydrogen-mixed natural gas at the outlet of the torch is discharged and continuously burning;
and step four, after the pressure of the upstream pipeline is reduced to 50%, opening a stop valve on the other branch pipeline until the discharge is finished.
Compared with the prior art, the invention has the following positive effects:
the invention provides a set of reasonable safe emptying system for the hydrogen-mixed natural gas valve chamber according to the combustion characteristics of hydrogen in the hydrogen-mixed natural gas and based on the combustion mechanism of the hydrogen. According to the system, on one hand, a facility for setting air to enter in the operation period isolation emptying system is omitted, and on the other hand, the safety problem in the discharge of the mixed hydrogen natural gas is avoided by setting strict replacement and compensation emptying functions. The system is characterized in that:
(1) science of setup
The invention adopts careful relief safety measures for relief of the hydrogen-mixed natural gas pipeline valve chamber based on the basic principle of hydrogen gas emptying and spontaneous combustion. Air in the emptying system is thoroughly isolated by arranging emptying pipeline replacement and torch cushion gas replacement; by arranging 2 emptying branch pipes, the instantaneous discharge rate in the emptying process is further ensured, and the positive pressure effect of the emptying system is kept; by providing a flare ignition system, bleed diffusion and air ingestion are prevented by the combustion of the medium. The effect of safe emptying of the hydrogen-mixed natural gas pipeline valve chamber is achieved by combining measures in various aspects.
(2) Good economical efficiency
The invention avoids the method of setting a power seal for long-term operation to isolate the air in the emptying system, and selects a more economic replacement mode before discharge by combining the objective conditions of the valve chamber.
(3) Advanced in concept
At present, a hydrogen-mixed natural gas pipeline is not built in a large range in China, related safety experience is few, and in view of the fact that the medium contains hydrogen and the hydrogen proportion is high, a relief result based on the combustion characteristic of the hydrogen needs to be focused on in the relief process, and the thought and the method provided by the invention provide reference and reference for the safe relief of the hydrogen-mixed natural gas pipeline valve chamber.
Drawings
The invention will now be described, by way of example, with reference to the accompanying drawings, in which:
FIG. 1 is a schematic diagram of a hydrogen-mixed natural gas pipeline valve chamber safety venting system of the invention.
Detailed Description
A mixed hydrogen natural gas pipeline valve room safety system of unloading mainly includes: the device comprises a
The main line cut-off system such as the
Through this system, carry out technical guarantee to the safe emptying of mixing hydrogen natural gas line block valve room. Before the valve chamber is emptied, the emptying pipeline is deeply replaced, so that air residue is avoided to the maximum extent, and the emptying safety is guaranteed, so as to replace the scheme of arranging continuous torch sealing; in the emptying process, in view of the problem of emptying tempering caused by the influence of hydrogen in the hydrogen-mixed natural gas, 2 emptying branch pipes are arranged, and the discharge capacity compensation is carried out in the middle and later periods of emptying, so that the problem of insufficient positive pressure in the emptying pipeline caused by low flow velocity in the emptying pipeline due to the reduction of upstream pressure in the middle and later periods of emptying is avoided; the torch with the field ignition function is arranged at the tail end of the emptying pipe, so that the discharged gas is fully combusted, and the hidden danger of diffusion explosion after the discharged gas is discharged is effectively avoided. Through the system, the hydrogen-mixed natural gas pipeline valve chamber can be safely and economically emptied, and the development of related technologies in the field is promoted.
Specifically, in the illustrated system, the
Specifically, in the system, a bypass external pipeline 9 is connected with a
Specifically, in the illustrated system, the replacement
The working principle of the invention is as follows:
when the main line of the hydrogen-mixed natural gas pipeline needs to be overhauled or when the main line of the hydrogen-mixed natural gas pipeline leaks, the cut-off
The invention also discloses a safe emptying method of the hydrogen-mixed natural gas pipeline valve chamber, which comprises the following main contents:
the method comprises the following steps: when the mixed hydrogen natural gas
Step two: when the mixed hydrogen natural gas in the upstream trunk line or the downstream trunk line is required to be discharged through the valve chamber, a No. 1 movable nitrogen supply device is connected with a joint of a bypass gas injection branch pipe (if the upstream trunk line is required to be discharged, the joint of the bypass gas
Step three: opening a main line
Step four: when the pressure of the upstream pipeline is reduced to 50%, the cut-off
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