WO2024066459A1 - 燃气管道天然气掺氢浓度控制方法、系统 - Google Patents
燃气管道天然气掺氢浓度控制方法、系统 Download PDFInfo
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- WO2024066459A1 WO2024066459A1 PCT/CN2023/098818 CN2023098818W WO2024066459A1 WO 2024066459 A1 WO2024066459 A1 WO 2024066459A1 CN 2023098818 W CN2023098818 W CN 2023098818W WO 2024066459 A1 WO2024066459 A1 WO 2024066459A1
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- Prior art keywords
- hydrogen
- natural gas
- flow
- regulating valve
- gas
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- 239000001257 hydrogen Substances 0.000 title claims abstract description 222
- 229910052739 hydrogen Inorganic materials 0.000 title claims abstract description 222
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 title claims abstract description 214
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 title claims abstract description 194
- 239000003345 natural gas Substances 0.000 title claims abstract description 99
- 238000000034 method Methods 0.000 title claims abstract description 48
- 239000002737 fuel gas Substances 0.000 title abstract description 5
- 230000001105 regulatory effect Effects 0.000 claims abstract description 68
- 230000001276 controlling effect Effects 0.000 claims abstract description 7
- 239000007789 gas Substances 0.000 claims description 90
- 238000002156 mixing Methods 0.000 claims description 53
- 238000005070 sampling Methods 0.000 claims description 25
- 230000008569 process Effects 0.000 claims description 16
- 230000003068 static effect Effects 0.000 claims description 9
- 230000003247 decreasing effect Effects 0.000 abstract 1
- 150000002431 hydrogen Chemical class 0.000 description 7
- 238000005259 measurement Methods 0.000 description 6
- 230000008859 change Effects 0.000 description 5
- 238000012360 testing method Methods 0.000 description 5
- 230000004044 response Effects 0.000 description 4
- 230000008901 benefit Effects 0.000 description 3
- 238000012937 correction Methods 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 101001121408 Homo sapiens L-amino-acid oxidase Proteins 0.000 description 2
- 102100026388 L-amino-acid oxidase Human genes 0.000 description 2
- 238000002485 combustion reaction Methods 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 229910000975 Carbon steel Inorganic materials 0.000 description 1
- 101100012902 Saccharomyces cerevisiae (strain ATCC 204508 / S288c) FIG2 gene Proteins 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000010962 carbon steel Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 238000005984 hydrogenation reaction Methods 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 238000012552 review Methods 0.000 description 1
- 238000013517 stratification Methods 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 238000012795 verification Methods 0.000 description 1
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
- F17D—PIPE-LINE SYSTEMS; PIPE-LINES
- F17D3/00—Arrangements for supervising or controlling working operations
- F17D3/12—Arrangements for supervising or controlling working operations for injecting a composition into the line
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
- F17D—PIPE-LINE SYSTEMS; PIPE-LINES
- F17D1/00—Pipe-line systems
- F17D1/02—Pipe-line systems for gases or vapours
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
- F17D—PIPE-LINE SYSTEMS; PIPE-LINES
- F17D3/00—Arrangements for supervising or controlling working operations
- F17D3/01—Arrangements for supervising or controlling working operations for controlling, signalling, or supervising the conveyance of a product
Definitions
- the invention belongs to the technical field of gas transportation, and in particular relates to a method and a control system for controlling the hydrogen blending concentration of natural gas in a gas pipeline.
- the hydrogen regulating valve is used to control the hydrogen concentration of natural gas in the gas pipeline.
- the principle is that natural gas is used as the main gas source, and hydrogen is injected into the natural gas as a mixed gas. Due to the active nature of hydrogen, when the concentration is high, there is a risk of hydrogen corrosion to the existing carbon steel gas pipeline.
- the downstream stoves also require that the hydrogen component of hydrogen-blended natural gas is within a certain range, and the Wobac number of the mixed gas meets the requirements of stable combustion of gas appliances, without explosion or flashback.
- the concentration of hydrogen In order to ensure the long-term safe operation of the gas supply system, the concentration of hydrogen must be controlled within the allowable range of the corresponding gas pipeline (currently required to be 0-20%).
- the common method in the industry is to use the hydrogen control valve backfeed method to control the concentration of mixed hydrogen, that is, generally taking the control signal given by the downstream gas chromatograph to control the opening size of the hydrogen control valve to ensure that the concentration of natural gas mixed with hydrogen is within the set range.
- One embodiment of the present invention provides a method for controlling the concentration of hydrogen blended natural gas in a gas pipeline, comprising the steps of:
- the first hydrogen flow regulating valve is calculated and adjusted to an opening value ⁇ 1 according to the difference (x-x1) to maintain the hydrogen flow rate tending to the flow rate Q2.
- FIG1 is a schematic diagram of a natural gas hydrogen blending concentration control system in a gas pipeline according to one embodiment of the present invention.
- FIG2 is a schematic diagram of a natural gas hydrogen blending concentration control system in a gas pipeline according to one embodiment of the present invention.
- the main problem with the existing control scheme is that, although the control logic is simple, the control efficiency is not high.
- the measurement data of the gas chromatograph is relatively accurate, but the sampling cycle is relatively long, generally 3-5 minutes. Controlling the concentration of hydrogen by the final detection result of the gas chromatograph will cause a long time to reach the control target.
- the final control result is that the valve opening is close to the set point, at least more than 5-10 minutes.
- the demand flow is unstable and changes rapidly, it is easy for the hydrogen concentration of natural gas to exceed the standard during some periods, which can easily cause unstable combustion and bring certain risks to the pipeline network and downstream gas stoves.
- a method for controlling the hydrogen concentration of natural gas in a gas pipeline includes the following steps:
- the first hydrogen flow regulating valve is calculated and adjusted to an opening value ⁇ 1 according to the difference (x-x1) to maintain the hydrogen flow rate tending to the flow rate Q2.
- the natural gas hydrogen blending scheme of the disclosed embodiment adopts a follow-up flow mixing process, with one natural gas source as the active gas source, and the other hydrogen source changes according to a preset volume ratio following the change of the active gas source.
- the gas source with a larger flow rate is set as the active gas source, and the gas source with a smaller flow rate is set as the follow-up gas source.
- control method disclosed in the present invention is to control the opening of the hydrogen regulating valve so that the hydrogen concentration of the natural gas after hydrogen blending is kept within the set range x1 to the maximum extent.
- the specific control process can be:
- the demand Q1 of downstream customers is obtained through the natural gas flow meter, and the flow rate Q2 of the blended hydrogen is calculated according to the set value x1 of the blending concentration.
- the opening value ⁇ 0 of the hydrogen regulating valve is calculated through the hydrogen valve coefficient, thereby obtaining the driving signal of the initial opening position of the main control signal.
- the actual valve opening ⁇ is continuously fed back until the actual opening reaches the calculated opening value ⁇ 0.
- the concentration data x of the hydrogen-blended natural gas actually measured by the density meter is compared with the concentration signal set x1. If it is lower, the hydrogen valve opening ⁇ increases, if it is higher, the hydrogen valve opening ⁇ decreases, if they are consistent, the hydrogen valve opening ⁇ 1 is maintained, and the step-by-step opening value ⁇ MIN is determined by the minimum step value of the corresponding hydrogen regulating valve.
- x and x1 can be expressed in percentage.
- the follow-up control is carried out in the form of forward and backward feed, under the premise of stable pressure of natural gas and hydrogen, the instantaneous flow meter signals of the main gas source (natural gas) and the follow-up gas source (hydrogen) are calculated by the forward feed, and the main control signal of the regulating valve is output.
- the regulating valve first quickly reaches the final regulating valve position required according to the main control signal, and can quickly respond to flow changes and shorten the response time.
- the backfeed is obtained by testing the density change of the mixed gas before and after blending, and the main controller CPU of the control system calculates the actual concentration of the mixed hydrogen, and quickly provides the regulating valve with a precision control signal in seconds to improve the control accuracy.
- the disclosed embodiment improves the control efficiency of the follow-up hydrogen regulating valve in the hydrogen mixing process, and improves
- the response speed of the hydrogen blending process can meet the requirements of safe operation of gas pipelines and downstream cookers, and achieve a fast and efficient level.
- the biggest feature of the control method disclosed in the present invention is that it combines the advantages of two different controls.
- the feedforward signal solves the problem of the response speed of the regulating valve, which is aimed at the main shortcomings of the original control method, such as low efficiency of the valve and long opening cycle. First, a rough adjustment is performed, and the valve opening is determined according to the calculation of the measured flow of natural gas and hydrogen.
- the actual control signal is given by the station control system, which can greatly improve the equipment response speed and improve the control efficiency of the natural gas hydrogen blending equipment station control.
- the feedback signal solves the problem of control accuracy.
- the final control result obtained by the actual measured physical quantity calculation is quickly obtained. Near the equilibrium position, the control upper limit set by the hydrogen concentration of natural gas is continuously corrected. While improving the control speed, the final control accuracy of the hydrogen blending equipment system can also be achieved, ensuring the overall control accuracy of the pipeline gas hydrogen blending system.
- the biggest benefit of this method is that the control cycle of the original minute level (3-5 minutes) is shortened to the control cycle of the second level (5-10 seconds), which improves the control efficiency.
- a natural gas hydrogen blending concentration control system for a gas pipeline includes a main controller, and a natural gas flow regulating valve, a natural gas flow meter, a first hydrogen flow regulating valve, and a hydrogen blending flow meter that are communicatively connected to the main controller.
- the natural gas flow regulating valve and the natural gas flow meter are arranged before the hydrogen mixing point of the natural gas input section of the gas pipeline.
- the first hydrogen flow regulating valve and the hydrogen-mixed hydrogen flow meter are arranged before the hydrogen mixing point of the hydrogen input section of the gas pipeline.
- the main controller calculates the opening value ⁇ 0 of the first hydrogen flow regulating valve according to the flow Q2, and drives the first hydrogen flow regulating valve to the opening value ⁇ 0.
- the main controller obtains the measured hydrogen mixing concentration x of the gas pipeline, calculates and adjusts the first hydrogen flow regulating valve to the opening value ⁇ 1 according to the difference (x-x1), so as to maintain the hydrogen flow rate tending to the flow Q2.
- SAMSON’s 3241-1DN15 pneumatic control valve can be selected as the hydrogen control valve, and a high-precision SAMSON 3731-3 pneumatic valve positioner can be used to pneumatically control the valve opening.
- the system provides a matching nitrogen meter, and the control system can accurately control the valve opening and provide real-time feedback of the actual opening value.
- a second hydrogen delivery pipeline can also be selected as a backup, and the second hydrogen flow control valve can be used to control the hydrogen flow.
- the control method of the embodiment of the present disclosure is relatively complex in terms of program, and has two signal control logics: feedforward and feedback.
- the control priority is distinguished, that is, efficiency is controlled first, and accuracy is controlled later.
- This method is very consistent with the actual needs of pipeline gas hydrogen blending equipment.
- the two signal sources themselves also shorten the signal sampling cycle as much as possible, and change the detection method from the original minute level to the current second level. Only in this way can the purpose of improving the overall control efficiency be truly achieved, and the risk of excessive hydrogen concentration caused by rapid changes in downstream flow can be reduced.
- the actual control method can also directly control the actual opening of the hydrogen regulating valve by the calculated data, assisted by the data authentication of the valve opening calculated by the metering data, that is, the feedback signal is used to locate first, and the feedforward data is used for safety review, which can also improve the control speed and safety level of the entire hydrogen blending station control. That is, the two feedforward and feedforward signals can be switched freely, and the control system determines which is the feedforward signal and which is the feedback signal according to the actual speed of data acquisition.
- a natural gas pipeline hydrogen concentration control system includes a main controller, and a natural gas flow control valve, a natural gas flow meter, a first hydrogen flow control valve, and a hydrogen flow meter connected to the main controller.
- the control system also includes a main controller connected to the main controller. A first gas density meter and a second gas density meter of the controller.
- the first gas density meter is set at the sampling position before natural gas is mixed with hydrogen in the gas pipeline
- the second gas density meter is set at the sampling position after natural gas is mixed with hydrogen in the gas pipeline.
- the main controller obtains the density ⁇ 1 from the first gas density meter and the density ⁇ 2 from the second gas density meter.
- the gas density meter here can be Emerson Micro Motion's gas density meter GDM5AAAC2Z1MZZZ.
- a static mixer is provided at the place where the natural gas is mixed with hydrogen in the gas pipeline, and the input natural gas and hydrogen are input into the static mixer, and a mixed gas is obtained after mixing in the static mixer.
- a gas chromatograph is also provided at the sampling position after the natural gas is mixed with hydrogen in the gas pipeline, and the output result of the gas chromatograph is input into the main controller.
- the natural gas hydrogen blending concentration control system for the gas pipeline is designed with two different mixing methods, one with a static mixer and the other without a static mixer, in order to test the effect of the static mixer.
- Sampling is tested separately by two high-precision gas density meters in front and behind to obtain the corresponding blending operation data.
- the latter gas density also takes into account the test positions at different heights of the pipeline.
- the sampling tube can be inserted into the pipeline at different depths to compare the differences in the test results, thereby verifying whether gas stratification will occur after blending.
- the reliability of the test method of calculating the hydrogen concentration after blending using the test gas density is verified by selecting data comparison at multiple points.
- the system has reserved an interface at the outlet, and a traditional gas chromatograph can be added for comparison.
- the ⁇ H plan uses a hydrogen density database, which can automatically match relevant data based on the actual temperature data measured on site, improve measurement accuracy, and reduce calculation errors.
- the embodiment of the present disclosure adopts an indirect measurement method to determine the hydrogen concentration of natural gas in pipeline fuel gas.
- the specific method is to use high-precision instruments to quickly measure the physical quantity or physical property changes of the gas , combined with computer technology, and use a high-performance microprocessor calculation program to calculate the hydrogen concentration in the pipeline natural gas , shorten the hydrogen concentration measurement cycle, and improve the safety level of the pipeline gas hydrogen blending process.
- pipeline natural gas is not a mixture of stable components, but in a certain period of time before and after hydrogen blending, in addition to the addition of hydrogen, under normal temperature conditions, the natural gas components are relatively stable, the total mass and molar amount are conserved, and no chemical reaction occurs.
- the actual concentration of hydrogen blended in natural gas can be quickly calculated.
- the measurement speed of the hydrogen concentration of natural gas can be greatly improved.
- the feedback time can be achieved in seconds, which improves the self-control efficiency of the hydrogen blending process, reduces the probability of excessive hydrogen concentration in the natural gas hydrogen blending process, and reduces the safety risk of operating pipelines.
- the control efficiency of the hydrogen blending process can be quickly provided, and the measurement cycle is reduced from no less than 2 minutes (60 seconds) to seconds, providing accurate gas density values, greatly improving the safety and reliability of the gas pipeline hydrogen blending process, and ensuring the feasibility of hydrogen transportation in existing gas pipelines.
- the beneficial effects of the present disclosure include:
- the hydrogen regulating valve is first driven to open quickly and directly to the initial opening position.
- This method is different from the slow opening method of the conventional regulating valve.
- the main purpose is to improve the efficiency of control implementation, reduce the actual difference between the actual hydrogenation amount and the set value during the hydrogen blending process, and improve the utilization rate of hydrogen energy. Then, a more reliable signal such as the actual measured value of the hydrogen concentration of the control system is used to make a high-precision correction to the opening.
- One of the innovations of this method is to greatly improve the control efficiency.
- the main idea of the control method disclosed in the present invention is to use feedforward for rough adjustment and feedback for fine adjustment, and to closely integrate the control cycle through the pre-setting of priority levels. After the main control valve is opened, it notifies the upper system and automatically switches to the secondary control state. The two methods are closely integrated, which can improve the control speed without reducing the control accuracy. The rapid and deep integration of the two controls can ultimately achieve the purpose of improving the control efficiency of the hydrogen regulating valve.
- the control system disclosed in the present invention is a breakthrough in the traditional control method. It uses two different data signals to adjust a control variable. During the process, the station control system can select the optimal signal based on the data signal acquisition speed. The signal with a faster acquisition speed is used as the feedforward signal, and the signal with a slower acquisition speed is used as the feedback signal for complex control. core or high-precision correction, allowing flexible selection of signal sources.
- the control system of the present disclosure selects the signal source based on the principle of higher control efficiency, that is, the priority is adopted in the speed determination of signal acquisition. That is, the signal calculated by the flow meter signal acquisition is compared with the station control signal calculated by the density meter actual measurement.
- the signal with a faster acquisition speed is used as the main signal for feedforward, and the other is used as a verification signal or a correction signal for feedback, so as to better improve the control efficiency and safety level of the hydrogen blending equipment.
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Abstract
本发明公开了一种燃气管道天然气掺氢浓度控制方法，包括步骤，获得燃气管道输入天然气的流量Q1，按氢气掺混浓度的设定值x1计算出掺混氢气的流量Q2＝Q1*x1,根据流量Q2计算第一氢气流量调节阀开度值η0，驱动第一氢气流量调节阀至开度值为η0，获取燃气管道的实测掺氢浓度x，根据差值(x-x1)计算并调节第一氢气流量调节阀至开度值η1，以维持氢气流量趋向于流量Q2。当x<x1，增大第一氢气流量调节阀开度η，当x>x1，减小第一氢气流量调节阀开度η。当天然气流量Q1发生变化，则重新计算掺混氢气的流量Q2＝Q1*x1。
Description
本发明属于燃气输送技术领域，特别涉及一种燃气管道天然气掺氢浓度控制方法和控制系统。
采用氢气调节阀来控制燃气管道中天然气的掺氢浓度，其原理是，以天然气为主气源，氢气作为掺混气注入天然气中。由于氢气性质活泼，浓度高时对现有燃气碳钢管道具有氢蚀的风险，同时下游灶具也要求掺氢天然气的氢气组分在一定范围内，混合气体的华白数符合燃气具稳定燃烧的要求，不出现爆燃或回火的情况。
为确保燃气供应系统长期安全运行，必须控制氢气的浓度在对应燃气管道允许的范围内(目前要求为0-20％)。行业内常用的方式是采用氢气调节阀后馈的方式控制掺混氢气浓度，即一般取下游气体色谱分析仪给出控制信号，控制氢气调节阀的开度大小，确保天然气掺混氢气的浓度在设定的范围内。
发明内容
本发明实施例之一，一种燃气管道天然气掺氢浓度控制方法，包括步骤，
获得燃气管道输入天然气的流量Q1，
按氢气掺混浓度的设定值x1计算出掺混氢气的流量Q2＝Q1*x1,
根据流量Q2计算第一氢气流量调节阀开度值η0，
驱动第一氢气流量调节阀至开度值为η0，
获取燃气管道的实测掺氢浓度x，
根据差值(x-x1)计算并调节第一氢气流量调节阀至开度值η1，以维持氢气流量趋向于流量Q2。
当x<x1，增大第一氢气流量调节阀开度η，
当x>x1，减小第一氢气流量调节阀开度η。
通过参考附图阅读下文的详细描述，本发明示例性实施方式的上述以及其他目的、特征和优点将变得易于理解。在附图中，以示例性而非限制性的方式示出了本发明的若干实施方式，其中：
图1根据本发明实施例之一的燃气管道天然气掺氢浓度控制系统示意图。
图2根据本发明实施例之一的燃气管道天然气掺氢浓度控制系统示意图。
10——天然气流量调节阀，
20——第一氢气流量调节阀，
30——第二氢气流量调节阀，
40——天然气流量计，
50——氢气流量计。
现有控制方案存在的主要问题是，虽然控制逻辑简单，但控制效率不高。气体色谱分析仪的测量数据比较准确，但是采样周期较长，一般在3-5分钟，通过气体色谱分析仪的最终检测结果来控制氢气的浓度会造成达到控制目标需要较长的时间，考虑氢气的浓度上限的安全要求，如果下游流量需求稳定，最终控制结果是阀门开度接近设定点，至少在5-10分钟以上。但如果需求流量不稳定，变化比较快速，那么很容易出现部分时段天然气掺氢浓度超标，容易造成燃烧不稳定和对管网和下游用气灶具带来一定的风险。
根据一个或者多个实施例，一种燃气管道天然气掺氢浓度控制方法，包括以下步骤，
获得燃气管道输入天然气的流量Q1，
按氢气掺混浓度的设定值x1计算出掺混氢气的流量Q2＝Q1*x1,
根据流量Q2计算第一氢气流量调节阀开度值η0，
驱动第一氢气流量调节阀至开度值为η0，
获取燃气管道的实测掺氢浓度x，
根据差值(x-x1)计算并调节第一氢气流量调节阀至开度值η1，以维持氢气流量趋向于流量Q2。
当x<x1，增大第一氢气流量调节阀开度η，
当x>x1，减小第一氢气流量调节阀开度η。
当天然气流量Q1发生变化，则重新计算掺混氢气的流量Q2＝Q1*x1。
本公开实施例的天然气掺氢方案采用随动式流量混合工艺，以一种天然气气源为主动气源，另一种氢气源按预先设定的体积比例跟随主动气源的变化而变化。将流量较大的气源设定为主动气源，流量较小的气源设定为随动气源，通过控制随动气源管道上的调节阀开度来实时快速响应主动气源的变化。
如图1所示，本公开的控制方法是对氢气调节阀的开度进行控制，使天然气掺氢后氢气浓度保持最大限度保持在设定范围x1内。具体控制过程可以是：
1.首先通过天然气的流量计获得下游客户的需求量Q1，按掺混浓度的设定值x1,计算出掺混氢气的流量Q2,结合各自对应的运行压力和温度，通过氢阀阀系数计算获得氢气调节阀的开度值η0，从而获得主控信号最初的开启位置的驱动信号。
2.开启过程中不断反馈阀门的实际开度η，直到实际开度达到计算开度值η0，这时开始由密度计实际测定的掺氢天然气的浓度数据x与设定x1的浓度信号进行比对，如果低了，氢阀开度η增大，如果高了，氢阀开度η减小，如果一致，则保持氢阀的开度η1，其步进变化的开度值ηMIN由对应氢气调节阀的最小步进值决定。这里的x与x1可以用百分比表示。
3.如果一段时间天然气流量Q1保持不变，则该流程持续保持，如果天然气的流量变化幅度超过±1％，则该流程重新开始，直至达到稳定的状态Q1。
由于采用前、后馈的方式进行随动控制，在天然气和氢气来气压力稳定的前提下，前馈为主气源(天然气)和随动气源(氢气)的瞬时流量计信号加以计算，输出调节阀主控制信号，调节阀首先根据该主控信号快速达到需要达到的最终调节阀位位置附近，能快速响应流量的变化，缩短响应时间，后馈取通过测试掺混前后混合气的密度变化，由控制系统主控制器CPU计算出实际掺混氢气的浓度，秒级快速为调节阀提供精度控制信号，提高控制精度。通过上述前馈和后馈的结合，最大限度提高掺氢工艺氢气调节阀的整体控制效率和控制精度。
因此，本公开实施例提高了掺氢工艺中随动氢气调节阀的控制效率，提高
掺氢工艺的响应速度，能够满足燃气管道和下游灶具安全运行的要求，达到快速高效的程度。本公开的控制方式最大的特点是，综合两种不同的控制优点，前馈信号解决调节阀的响应速度的问题，针对的是原有控制方式的效率低阀、开到位周期长的主要缺点，先进行粗调节，根据天然气和氢气的实测流量的计算，使阀的开度确定下来，由站控系统给出实际的控制信号，能够使设备响应速度大幅提高，提高天然气掺氢设备站控的控制效率。后馈信号解决控制精度的问题，针对实际实测物理量计算快速得到的最终控制结果，在平衡位置的附近，不断修正逼近天然气混氢浓度设定的控制上限，在提高控制速度的同时，也能够掺氢设备系统的最终控制精度，确保管道燃气掺氢系统的整体控制精度。该方式最大的益处是从原先分钟级的控制周期(3-5分钟)缩短至秒级的控制周期(5-10秒)，提升了控制效率。
根据一个或者多个实施例，一种燃气管道天然气掺氢浓度控制系统，该控制系统包括主控制器，以及与主控制器通信连接的天然气流量调节阀、天然气流量计、第一氢气流量调节阀、掺氢氢气流量计。
天然气流量调节阀和天然气流量计设置于燃气管道天然气输入段之掺氢混合处之前的位置，第一氢气流量调节阀和掺氢氢气流量计设置于燃气管道氢气输入段之掺氢混合处之前的位置，主控制器从天然气流量计获得燃气管道输入天然气的流量Q1，按氢气掺混浓度的设定值x1计算出掺混氢气的流量Q2＝Q1*x1。主控制器根据流量Q2计算第一氢气流量调节阀开度值η0，驱动第一氢气流量调节阀至开度值为η0。主控制器获取燃气管道的实测掺氢浓度x，根据差值(x-x1)计算并调节第一氢气流量调节阀至开度值η1，以维持氢气流量趋向于流量Q2。
进一步的，通过设置于天然气管道中的天然气流量计获取天然气的流量Q1，按氢气掺混浓度的设定值x1计算出掺混氢气的流量Q2＝Q1*x1。
比较实测掺氢浓度x的采样速度、天然气流量计流量Q1的采样速度，如果实测掺氢浓度x的采样速度较快，则有：根据差值(x-x1)计算并调节第一氢气流量调节阀至开度值η1，然后根据天然气流量计流量Q1对第一氢气流量调节阀开度进行修正；如果天然气流量计流量Q1的采样速度较快，则有：根据流量Q2＝Q1*x1计算并调节第一氢气流量调节阀至开度值η0，然后根据实
测掺氢浓度x对第一氢气流量调节阀开度进行修正。
比较实测掺氢浓度x的采样速度、掺氢氢气流量计的采样速度，如果实测掺氢浓度x的采样速度较快，则有：根据差值(x-x1)计算并调节第一氢气流量调节阀至开度值η1，然后根据天然气流量计流量Q1对第一氢气流量调节阀开度进行修正；如果掺氢氢气流量计的采样速度较快，则掺氢氢气流量计的输出值记为流量Q2，调节第一氢气流量调节阀至开度值η1，然后根据天然气流量计流量Q1对第一氢气流量调节阀开度进行修正。
在本公开实施例中，可以选择SAMSON的3241-1DN15的气动调节阀作为氢气调节阀，并配套高精度的SAMSON 3731-3的气动阀门定位器对阀门开度进行气动控制，系统提供配套氮气仪表，由控制系统可以精确的对阀门开度进行控制和实时反馈实际开度值。如图1所示，还可以选用第二条氢气输送管道作为备份，由第二氢气流量调节阀进行氢气流量调节控制。两路氢气调节阀，一开一备，如果主路失效，副路调节阀自动开启，并关闭主路调节阀，提高整个系统的掺氢控制可靠性。
本公开实施例的制方式相对于单一的控制逻辑的调节阀自控，从程序上讲相对复杂，为先前馈、后后馈两种信号控制逻辑。由控制优先级进行区分，即先控制效率，后控制精度，该种方式非常符合管道燃气掺氢设备的实际需求。同时两种信号源本身也尽可能缩短信号采样周期，改变检测的方法，从原先的分钟级上升至目前的秒级，这样才能真正的达到提升整体控制效率的目的，能够减少下游流量快速变化所带来的掺氢浓度超标的风险。
如果控制系统的主控制器CPU由物理量密度计算实际氢气浓度的速度足够快，实际的控制方式也可直接由该计算数据控制氢气调节阀的实际开度，辅助以计量数据计算的阀开度的数据认证，即后馈信号来先进行定位，由前馈数据进行安全复核，也能提升整个氢气掺混站控的控制速度和安全等级。即前后馈两种信号可以自由切换，控制系统根据数据采集的实际速度确定哪种是前馈信号，哪种是后馈的信号。
根据一个或者多个实施例，一种燃气管道天然气掺氢浓度控制系统，该控制系统包括主控制器，以及与主控制器通信连接的天然气流量调节阀、天然气流量计、第一氢气流量调节阀、掺氢氢气流量计。所述控制系统还包括接入主
控制器的第一气体密度计、第二气体密度计。
第一气体密度计设置于燃气管道中天然气掺混氢气前的取样位置，第二气体密度计设置于燃气管道中天然气掺混氢气后的取样位置。主控制器从第一气体密度计处获得所述密度ρ1，从第二气体密度计处获得所述密度ρ2。
设氢气密度为ρH，则主控制器计算获得天然气掺氢后氢气的浓度为x，x＝(ρ1-ρ2)/(ρ1-ρH)。这里的气体密度计可以采用艾默生Micro Motion的气体密度计GDM5AAAC2Z1MZZZ。
进一步的，在燃气管道中天然气掺混氢气处设置有静态混合器，输入的天然气和氢气输入所述静态混合器，在所述静态混合器内混合后获得混合气。在燃气管道中天然气掺混氢气后的取样位置处还设置有气体色谱分析仪，该气体色谱分析仪的输出结果输入所述主控制器。
如图2所示，燃气管道天然气掺氢浓度控制系统设计了两路不同的混合方式，一路有静态混合器，一路不设静态混合器，是为了测试静态混合器的效果。取样都是在前后两个高精度的气体密度计各自测试，获取相应的掺混运行数据。其中后一个气体密度还同时考虑到管道不同高度的测试位置，取样管可对应插入管道内不同的深度，比对测试的结果的差异，从而验证是否会出现掺混后气体分层的情况。通过选取多个点的数据比对，来验证采用测试气体密度计算掺混后氢气浓度测试方法的可靠性。系统在出口处预留了接口，可加设传统的气体色谱分析仪进行对比。
以1个标准大气压，环境温度为20℃为例，设天然气掺混前的密度为ρ1,天然气掺混后的密度为ρ2，查氢气的密度表，对应氢气的20℃密度按0.082658×103kg/Nm3,天然气掺氢后氢气的摩尔浓度设为x，对应公示为ρ1(1-x)+0.082658x＝ρ2,掺氢后天然气的密度下降，ρ2〈ρ1
则x＝(ρ1-ρ2)/(ρ1-0.082658)……公式(1)
考虑氢气的密度也是随环境温度变化，设氢气密度为ρH
则公式(1)改为x＝(ρ1-ρ2)/(ρ1-ρH)……公式(2)
其中ρH计划采用氢气的密度数据库，可以根据现场实测温度的数据自动匹配相关的数据，提升测量的精确度，降低计算误差。
本公开实施例采用间接测量的方法来测定管道燃气中天然气的掺氢浓度。
具体方法是采用高精度仪表快速测量气体物理量或物理性质变化的方法，结合计算机技术，通过高性能微处理器计算程序来计算管道天然气中的掺氢浓度，缩短氢气浓度测量的周期，提升管道燃气掺氢工艺的安全水平。考虑管道天然气并非一种稳定组分的混合物，但一定时间内在掺氢前后除了增加氢气外，常温条件下，天然气组分相对稳定，总质量和摩尔量守恒，不会发生化学反应。例如，通过直接测量掺混氢气天然气的密度变化，结合本地的高性能微处理器，快速计算出天然气中掺混氢气的实际浓度。
通过上述方法，根据气体密度计仪表的本身反馈时间，天然气掺氢浓度的测量速度可以大幅度提升，理论上可以做到秒级反馈时间，提升掺氢工艺的自控效率，减少天然气掺氢工艺中氢气浓度超标的情况发生几率，降低运行管道的安全风险。
通过本公开实施例的燃气管道中天然气掺氢浓度的测量方法，可以快速提供掺氢工艺的控制效率，测量周期从之前的不少于2分钟(60秒)降低到以秒为单位，提供精确的气体密度值，极大的提高了燃气管道掺氢工艺的安全性和可靠性，确保现有燃气管道输送氢气的可行性。
综上所述，本公开的有益效果包括:
(1)首先结合实测流量值由控制系统计算出调节阀初步开度后，首先驱动氢气调节阀快速直接开启至初步开度的位置，该方法与常规调节阀慢开的方式不同，主要目的是为了提高实施控制的效率，缩小掺氢工艺过程中实际加氢量偏低于设定值的实际差异，提升氢能的利用率，之后再用可靠性更高信号如控制系统氢气浓度的实际测定值来对该开度进行高精度的修正，大幅度提升控制效率是本方法的创新点之一。
(2)本公开的控制方式的主体思路是先前馈粗调，后馈细调，通过优先级等级的预先设定，控制周期的紧密结合。主控阀开到位后通知上位系统，并自动切换到次控状态，两种方式密切整合，即能提升控制速度，又不降低控制精度，两种控制的快速深度融合，最终能够达到提升氢气调节阀的控制效率的目的，
(3)本公开的控制系统是对传统控制方法的突破，采用两种不同数据信号对一个控制变量进行调节，其过程中可以由站控系统根据数据信号的采集速度进行优选，那种信号采集速度快就作为前馈信号，速度慢信号作为后馈信号进行复
核或高精度修正，从而能够灵活选择信号源。
(4)本公开控制系统选择信号源是以更高控制效率为主要原则，也就是信号采集的速度判定采用优先级。也就是将流量计信号采集计算出的信号与密度计实测计算出的站控信号进行比对，哪种信号采集速度更快，就作为前馈的主信号，另一种就作为复核信号或后馈的校正信号，从而更好提升掺氢设备的控制效率和安全等级。
值得说明的是，虽然前述内容已经参考若干具体实施方式描述了本发明创造的精神和原理，但是应该理解，本发明并不限于所公开的具体实施方式，对各方面的划分也不意味着这些方面中的特征不能组合，这种划分仅是为了表述的方便。本发明旨在涵盖所附权利要求的精神和范围内所包括的各种修改和等同布置。
Claims (9)
- 一种燃气管道天然气掺氢浓度控制方法，其特征在于，包括以下步骤，获得燃气管道输入天然气的流量Q1，按氢气掺混浓度的设定值x1计算出掺混氢气的流量Q2＝Q1*x1,根据流量Q2计算第一氢气流量调节阀开度值η0，驱动第一氢气流量调节阀至开度值为η0，获取燃气管道的实测掺氢浓度x，根据差值(x-x1)计算并调节第一氢气流量调节阀至开度值η1，以维持氢气流量趋向于流量Q2。
- 根据权利要求1所述控制方法，其特征在于，当x<x1，增大第一氢气流量调节阀开度η，当x>x1，减小第一氢气流量调节阀开度η。
- 根据权利要求1所述控制方法，其特征在于，当天然气流量Q1发生变化，则重新计算掺混氢气的流量Q2＝Q1*x1。
- 根据权利要求1所述控制方法，其特征在于，通过设置于天然气管道中的天然气流量计获取天然气的流量Q1，按氢气掺混浓度的设定值x1计算出掺混氢气的流量Q2＝Q1*x1,比较实测掺氢浓度x的采样速度、天然气流量计流量Q1的采样速度，如果实测掺氢浓度x的采样速度较快，则有：根据差值(x-x1)计算并调节第一氢气流量调节阀至开度值η1，然后根据天然气流量计流量Q1对第一氢气流量调节阀开度进行修正，如果天然气流量计流量Q1的采样速度较快，则有：根据流量Q2＝Q1*x1计算并调节第一氢气流量调节阀至开度值η0，然后根据实测掺氢浓度x对第一氢气流量调节阀开度进行修正。
- 根据权利要求4所述控制方法，其特征在于，比较实测掺氢浓度x的采样速度、掺氢氢气流量计的采样速度，如果实测掺氢浓度x的采样速度较快，则有：根据差值(x-x1)计算并调节第一氢气流量调节阀至开度值η1，然后根据天然气流量计流量Q1对第一氢气流量调节阀开度进行修正，如果掺氢氢气流量计的采样速度较快，则掺氢氢气流量计的输出值记为流 量Q2，调节第一氢气流量调节阀至开度值η1，然后根据天然气流量计流量Q1对第一氢气流量调节阀开度进行修正。
- 根据权利要求1所述控制方法，其特征在于，获取燃气管道的实测掺氢浓度x的过程包括，获得燃气管道中天然气掺混氢气前的密度ρ1；获得燃气管道中天然气掺混氢气后的密度ρ2；设氢气密度为ρH，天然气掺氢后氢气的浓度为x，
x＝(ρ1-ρ2)/(ρ1-ρH)。 - 一种燃气管道天然气掺氢浓度控制系统，其特征在于，该控制系统包括主控制器，以及与主控制器通信连接的天然气流量调节阀、天然气流量计、第一氢气流量调节阀、掺氢氢气流量计，天然气流量调节阀和天然气流量计设置于燃气管道天然气输入段之掺氢混合处之前的位置，第一氢气流量调节阀和掺氢氢气流量计设置于燃气管道氢气输入段之掺氢混合处之前的位置，主控制器从天然气流量计获得燃气管道输入天然气的流量Q1，按氢气掺混浓度的设定值x1计算出掺混氢气的流量Q2＝Q1*x1,根据流量Q2计算第一氢气流量调节阀开度值η0，主控制器驱动第一氢气流量调节阀至开度值为η0，主控制器获取燃气管道的实测掺氢浓度x，根据差值(x-x1)计算并调节第一氢气流量调节阀至开度值η1，以维持氢气流量趋向于流量Q2。
- 根据权利要求7所述的控制系统，其特征在于，所述控制系统还包括接入主控制器的第一气体密度计、第二气体密度计，第一气体密度计设置于燃气管道中天然气掺混氢气前的取样位置，第二气体密度计设置于燃气管道中天然气掺混氢气后的取样位置主控制器从第一气体密度计处获得所述密度ρ1，从第二气体密度计处获得所述密度ρ2，设氢气密度为ρH，则主控制器计算获得天然气掺氢后氢气的浓度为x，
x＝(ρ1-ρ2)/(ρ1-ρH)。 - 根据权利要求7所述的控制系统，其特征在于，在燃气管道中天然气掺混氢气处设置有静态混合器，输入的天然气和氢气输入所述静态混合器，在所述静态混合器内混合后获得混合气。
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| CN115585401A (zh) * | 2022-09-30 | 2023-01-10 | 上海飞奥燃气设备有限公司 | 燃气管道天然气掺氢浓度控制方法、系统 |
| CN116452831B (zh) * | 2023-04-27 | 2024-06-07 | 中国长江三峡集团有限公司 | 天然气掺氢燃烧系统调整方法、装置及电子设备 |
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