Low Pressure Gas Pipelines Research Articles

Leakage detection of low-pressure gas distribution pipeline system based on linear fitting and extreme learning machine

Pipelines are the lifeblood of the natural gas market. Compared with the high-pressure long-distance pipeline system and medium-pressure municipal pipeline system, the leak detection of low-pressure gas distribution pipeline system inside buildings that only relies on the combustible gas alarm is relatively backward and passive. Based on the principle of the negative pressure wave method, we proposed a leak detection method combining linear fitting and extreme learning machine leak detection. We designed and built a low-pressure gas pipeline system, which truly reproduces the gas leakage scenes inside buildings. By establishing multi-dimensional sliding windows, combined with a linear fitting method, the original pressure signal can be initially screened. Small leakage and pipe network fluctuations can be effectively identified by the windows. For medium leakage, large leakage, and gas usage that are easy to be confused, the windows will accurately identify the inflection point of the pressure drop for subsequent processing. Aiming at the characteristics of negative pressure waves, we extracted 15-dimensional feature vectors by dividing different stages. After introducing extreme learning machine for training, the detection accuracy of the final model can reach more than 90 %. Compared with support vector machines and back propagation neural networks, the trained extreme learning machine model has higher accuracy and higher speed. The joint leak detection algorithm based on linear fitting and extreme learning machine can greatly reduce the number of gas leakage accidents of low-pressure gas pipeline system through single point pressure monitoring. We applied the artificial intelligence algorithm and negative pressure wave to the low-pressure pipeline system for the first time, and established a new pressure wave processing method, characteristic model and algorithm model, which has a good engineering application prospect and theoretical significance.

Current state of the gas industry of the republic of kazakhstan

The Republic of Kazakhstan possesses large reserves of natural resources. Gas is one of the most demanded energy resources in the world today. Kazakhstan is one of the 30 leading countries in terms of gas reserves and production, while constantly increasing its production potential and expanding its sphere of influence in the gas field in the world. In percentage terms, Kazakhstan owns 1.7% of the world's proven natural gas reserves. This article analyzes the indicators of the country's gas industry development. There was prepared a forecast of natural gas production up to 2030, it was made using the Brown model of moving average (CC model). The analysis of indicators of gas transportation through pipelines, such as transit and export, is made. The location on the map plays an important role in the development of the gas industry in Kazakhstan, as gas pipelines connecting Europe and Asia pass through its territory. Transit gas pipelines are used both for gas supplies to the domestic market of the country and for gas exports. The total length of high, medium and low pressure gas pipelines in Kazakhstan is 28,628 km. In addition to positive indicators indicating the stable development of the industry, the factors hindering the development of the gas industry of the Republic of Kazakhstan are identified.

Analysis of emergency situations on low pressure gas pipelines in case of failure of gas control points

The analysis of malfunctions of the main equipment at gas control points was carried out. It was concluded that for the looped-back part of the low-pressure network, the diameters of adjacent sections should not be significantly different, since if the diameter of one section is less than the neighboring one, then in an emergency mode, a section with a small diameter will not let in the required amount of gas.

Research on the Integrity Evaluation Technology for Urban Gas Pipeline

In order to research the new integrity evaluation technology of gas pipeline and promote the mature development of gas pipeline integrity management, this paper deeply analyzes the characteristics of Beijing gas pipeline and combines with the methods of finite element modeling, statistical analysis, mathematical fitting and experimental verification. Based on the Spangler-lowa method, the load effects of gas pipelines with different pressure grades are analyzed, a new method for evaluating the external load carrying capacity of gas pipeline with local corrosion defects was developed, and a method for evaluating the internal pressure carrying capacity of gas pipeline was determined. The research shows that the integrity structure evaluation of gas pipeline should be evaluated according to the pressure level. Medium- and low-pressure gas pipeline is mainly affected by external load, and deformation is the evaluation basis. The sub-high-pressure gas pipeline is affected by both external load and internal pressure, and its deformation and stress are taken as the evaluation basis respectively. High-pressure gas pipeline is mainly affected by internal pressure, and stress is the evaluation basis.

Machine learning and acoustic method applied to leak detection and location in low-pressure gas pipelines

The increase in pipeline safety would prevent incidents that can result in fatalities, environmental disasters, and economic losses. The present work proposes a technique that combines acoustic sensors and machine learning algorithms to identify and locate leakages in low-pressure gas pipelines. The patterns on the sound signal captured by microphones were used to accomplish those two tasks. The technique aims to solve two persistent problems, the detection of small leakages on pipelines operating under low pressures and the reduction of false alarms in the presence of external disturbances. The experimental results showed that the method identified 99.6% of the leakages and achieved a rate of false alarms of 0.3%, while the position of the leakages was estimated with a maximum location error of 4.31%. These results show that the technique proposed is an efficient and reliable alternative to monitor low-pressure pipelines.

Classification of gas reduction valve silencers at TPP gas distribution points

Gas distribution points (GDP) at TPPs are sources of intense noise. Results of noise experimental measurements originating from TPP GDP demonstrate that the sound level at a distance of 10 m could reach 110 dBA. Gas reduction valves are the source of noise in GDP. Noise emission characteristic of the gas reduction valves depends on their geometric and design parameters. To reduce the noise propagating in a low-pressure gas pipeline from gas reduction valves, various types of noise silencers are used. This paper presents results of noise experimental measurements in the vicinity of the GDP buildings at various energy enterprises. Overview and classification of silencers by various manufacturers used at TPP GDPs are provided.

Research of pressure influence in the gas supply system on the energy consuption level of gas devices

There are investigated the influence of operating pressures in the gas supply system on the level of such energy indicators as efficiency, gas flow and gas overrun by gas equipment in residential buildings. There is established a relationship between the values of operating pressures in the gas supply system and the gas consumption level of household appliances. The causes of insufficient pressure in the gas networks of settlements are analyzed in the article. There is also developed an algorithm for calculating the change in the efficiency of gas appliances depending on the operational parameters of the gas network. It has been found that the most efficient operation of gas appliances is observed at an overpressure at the inlet of gas appliances of about 1200 Pa.To ensure the required quality of natural gas combustion among consumers and minimize gas consumption there are justified the following measures in the article: coordinating a domestic regulatory framework for assessing the quality of natural gas with international norms and standards; improving the preparation of gas coming from local wells before supplying it to gas distribution networks; auditing low pressure gas pipelines and reconstructing areas affected by corrosion; ensuring standard gas pressure in the network for the normal operation of domestic gas appliances; stating quality indicators of natural gas combustion by gas sales organizations.

Investigation of Damage Ratio of Low-pressure Gas Pipeline at the Improved Hill in Sendai City after the 2011 Great East Japan Earthquake

Investigation of Damage Ratio of Low-pressure Gas Pipeline at the Improved Hill in Sendai City after the 2011 Great East Japan Earthquake

Experimental Validation of Leak and Water-Ingression Detection in Low-Pressure Gas Pipeline Using Pressure and Flow Measurements

In underground low-pressure gas distribution pipelines, ground water enters the pipeline through cracks. This is known as the water ingress problem, and it occurs predominantly in the monsoon season, when the water table is high. This issue is currently detected based on complaints from the users. In order to arrive at an efficient and reliable processing technique, experimental results of pressure and flow on an existing low-pressure gas pipeline are reported in this paper. Several experiments for leak location, severity of the leak, water ingression with various volumes of water followed by removal of water are conducted. Healthy network loading data collected over a 24 h period is used to verify the robustness of the derived parameters for water ingression detection. The present technique can detect leaks easily with a leak valve opening of 30o. Robust detection of water ingression with more than 10% of pipe volume is possible.

Water Ingress Detection in Low-Pressure Gas Pipelines Using Distributed Temperature Sensing System

In a distribution network of low-pressure gas pipelines, the situation of gas leak can be further aggravated when groundwater enters the pipeline through leaks and eventually blocks the gas flow. This will have critical implications on the gas supply to the customers. This is termed as “water ingress,” which typically happens only in low-pressure distribution networks, and not in high-pressure transmission networks. In order to find the location of water ingress, distributed temperature sensing (DTS) system has been used experimentally. The results show significant temperature change immediately after the onset of water ingress, and with data post-processing based on temporal difference, location information of the leak can be obtained. With a selected time window of interest, the inclination of gas pipeline is also indicated by the differenced temperature profiles. The DTS system is still capable of identifying the position, even if the location of water ingress is changed.

Numerical Simulation of Sudden Gas Pipeline Leakage in Urban Block

Nowadays, the leakage model of low-pressure natural gas pipeline under the atmospheric environment has been established with the leak rate decrease with time. The Fluent software is used to simulate the concentration distribution and velocity distribution of gas among buildings at different time after the leakage, the influence of aspect ratio, distance between buildings is considered to maximally simulate the impact of external environment on natural gas leakage and diffusion. Finally we obtained the diffusion trend and concentration distribution under different conditions of gas leakage, so that rescue workers can acquire the transport status and influence of leaked gas in blocks in a short time, and provide a theory foundation for accident rescue.

Corrosion of Underground Low Pressure Gas Pipelines under Alternate Current

Під час експлуатації підземних газових мереж низького тиску не приділяють уваги боротьбі з електрокорозією під дією змінного струму. При цьому інтенсивні корозійні руйнування проходять у місцях стікання постійного струму зі зовнішньої поверхні в електроліт (ґрунт або воду). Проведено моніторинг корозійних уражень розподільчих трубопроводів "Івано-Франківськгаз". Виявлено локальні корозійні ураження, які за формою і глибиною відповідають електрокорозійним. Показано, що електрокорозія розподільчих газопроводів може бути зумовлена помилковим або навмисно неправильним підключенням електроприладів. Зафіксовано натікаючі струми навіть на малопотужних побутових приладах силою близько 4 А, що залежно від фізико-хімічних властивостей ґрунту відповідає густині струму на дефекті від 8,9 до 310 А/м2 за максимального нормативного значення 10 А/м2.

ОСОБЕННОСТИ МАЛОТОННАЖНОГО ПРОИЗВОДСТВА СПГ НА ГАЗОПРОВОДАХ НА ОСНОВЕ ДРОССЕЛЬНЫХ ЦИКЛОВ ВЫСОКОГО ДАВЛЕНИЯ

Liquefied natural gas (LNG) is widely used as an efficient energy source. Its production can be profitably implemented in gas pipelines of high and low pressure using different throttle cycles. We have examined LNG production based on the cycles of high pressure in low pressure gas pipelines (half-closed cycles) and gas distribution stations (open cycles). It is shown that during the liquefaction there occurs the degradation of the component composition of the circulating gas (half-closed cycles) or liquefied natural gas (open cycles). This reduces the performance of the units or the LNG quality. Technical solutions that eliminate the degradation of the composition and enable the production of high quality LNG are proposed.

Determination of the economical optimum insulation thickness for VRF (variable refrigerant flow) systems

This study deals with the investigation into optimum insulation thickness of installed inside building pipe network of VRF (variable refrigerant flow) systems. Optimum insulation thickness, energy savings over a lifetime of 10 years and payback periods are determined for high pressure gas pipelines, low pressure gas pipelines and low pressure liquid pipelines under the heating-only and cooling-only modes of the three-pipe VRF system using R-410A as refrigerant. By using the P1–P2 method, the value of the amount of the net energy savings is calculated. Under heating mode of VRF system, while the optimum insulation thickness varies between 16 and 20 mm depending on the pipe sections of high pressure gas pipeline, it varies from 11 to 13 mm for the pipe sections of low pressure liquid pipeline. Under cooling mode of VRF system, the optimum insulation thickness varies between 7 and 8 mm for pipe sections of low pressure gas pipeline and low pressure liquid pipeline.

Modeling of Natural Gas Transportation and Distribution in Low Pressure Gas Pipelines

It is known that the area of the implementation of automated systems for remote control of the technological processes of gas transportation and distribution, as well as its commercial metering and consumption is set for the settlements with population exceeding 100 thousand people. It has a centralized structure, including the lower level − controlled stations, and the upper level − central dispatcher board, which is implemented in the form of automation-equipped workstations connected using computer networks.