High-pressure Transmission Pipelines Research Articles

Blending low-carbon hydrogen with natural gas: Impact on energy and life cycle emissions in natural gas pipelines

Hydrogen (H2) is considered an alternative energy carrier to reduce greenhouse gas (GHG) emissions related to power and heat generation. A quantitative analysis was conducted to estimate the energy intensity and GHG emissions associated with the transportation of NG/H2 mixture in high-pressure transmission pipeline, considering blending ratios up to 100% of low-carbon H2. The life cycle emissions were obtained by including upstream supply chain emissions, compression and transportation emissions, and end use combustion emissions of the NG/H2 blend. This study accounts for global warming potential of fugitive methane and H2 emissions associated with pipeline transportation of the blend in the life cycle analysis. A significant reduction in the overall life cycle GHG emissions can be achieved when delivering the same volume throughput but at a reduced energy flow to end users. However, to maintain the nominal energy throughput of the pipeline regardless of the H2 mole fraction, a maximum reduction of about 6% is obtained as the H2 mole fraction in the blend will be practically limited to approximately 30% H2 when the pipeline operates at capacity.

Case study: Analysis and research on pipeline vibration of liquid oxygen kerosene of rocket engine and vibration reduction measures Measures

Abnormal vibration often occurs in the liquid oxygen kerosene transmission pipe- line of rocket engines, seriously threatening the safety of rocket engines. Improper handling will result in rocket launch failure and enormous economic losses. Therefore, the vibration of the transmission pipeline must be studied. In this paper, a three-dimensional high-pressure transmission pipeline model comprising a corrugated pipe, a multi-section bending pipe, and other auxiliary structures is established. Using the two-way fluid–solid coupling method, vibration analysis is performed on the pipeline under external pressure pulse excitation. The accuracy of the computation results is verified by a thermal test. Two vibration reduction strategies are presented and validated by simulation in accordance with the findings of the vibration study. The main conclusions are as follows: (1) At the same frequency, the amplitude distribution of vibration acceleration significantly correlates with the flow field pressure, indicating that fluid pressure fluctuation is the root cause of the abnormal vibration of the pipeline, and the vibration of the pipeline increases with the average pressure. (2) The time-average value and fluctuation amplitude of the larger stress and strain are mainly concentrated in the two supports, namely, the inside of the elbow and the bellows, which is different from the distribution of vibration acceleration. Such places are prone to structural failure and should be given attention. (3) The guide plate and the support enhancement method can reduce the vibration, but the support enhancement method has a better effect, reducing the vibration velocity and acceleration by 86.4% and 93%, respectively.

Energy Dissipation Effect in the One-Dimensional Limit of the Energy Equation in Turbulent Compressible Flow

The transportation of natural gas through high pressure transmission pipelines has been modeled by numerically solving the conservation equations for mass, momentum, and energy for one-dimensional compressible viscous heat conducting flow. Since the one-dimensional version is a result of averages over the pipe cross-section and the flow is normally turbulent, the order of averaging in space and time is an issue; in particular, for the dissipation term. The Reynolds decomposition and time averaging should be performed first, followed by the contraction to the one-dimensional version by the cross-sectional averaging. The result is a correction factor, which is close to unity, on the usual expression of the dissipation term in the energy equation. This factor will, to some extent, affect the temperature distribution along the pipeline. For low Reynolds numbers (Re≃104) it reduces the dissipation by as much as 7%, irrespective of roughness. For high Reynolds numbers (Re ≥ 107) and roughness in the high range of the micron decade, the dissipation is increased by 10%. If the pipeline is also thermally isolated such that the flow can be considered adiabatic, the effect of turbulent dissipation gains further importance.

Composite Repair and Reinforcement Technology for Oil and Gas Pipeline and its Development Trend

Pipeline repair and reinforcement technology can generally be categorized into three main types: Welding, Clamp, Fiber Composite. Fiber Composite Repair recently undergoes fast development because it does not require heat or welding and can be directly applied to high pressure transmission pipeline. This article summarizes Fiber Composite Repair technology and its mechanism, also compares the application characteristics of Glass Fiber, Carbon Fiber and Basalt Fiber composites and finally concludes broad application prospects of Carbon Fiber Composite in pipeline repair and reinforcement.

Large scale experiments to study fires following the rupture of high pressure pipelines conveying natural gas and natural gas/hydrogen mixtures

As part of the EC funded Naturalhy project, two large scale experiments were conducted to study the hazard presented by the rupture of high pressure transmission pipelines conveying natural gas or a natural gas/hydrogen mixture containing approximately 22% hydrogen by volume. The experiments involved complete rupture of a 150mm diameter pipeline pressurised to nominally 70bar. The released gas was ignited and formed a fireball which rose upwards and then burned out. It was followed by a jet fire which continued to increase in length, reaching a maximum of about 100m before steadily declining as the pipeline depressurised. During the experiments, the flame length and the incident radiation field produced around the fire were measured. Measurements of the overpressure due to pipeline rupture and gas ignition were also recorded. The results showed that the addition of the hydrogen to the natural gas made little difference to radiative characteristics of the fires. However, the fraction of heat radiated by these pipeline fires was significantly higher than that observed for above ground high pressure jet fires (also conducted as part of the Naturalhy project) which achieved flame lengths up to 50m. Due to the lower density, the natural gas/hydrogen mixture depressurised more quickly and also had a slightly reduced power. Hence, the pipeline conveying the natural gas/hydrogen mixture resulted in a slightly lower hazard in terms of thermal dose compared to the natural gas pipeline, when operating at the same pressure.

Development and assessment of a new operating principle for the measurement of unsteady flow rates in high-pressure pipelines

Instantaneous mass flow rate measurements in high-pressure transmission pipelines under transient flow conditions can be valuable for the analysis of hydraulic power systems. However, at present no reliable commercial measuring device is available for pressure levels beyond 300 bar. A new operating principle, of general application, for measuring the flow rate in high-pressure flows (from 300 to 2000 bar) was developed and assessed. The innovative device was capable of accurately evaluating the instantaneous mass flow rate on the basis of the pressure–time histories detected at two different locations by high-pressure transducers. The measurement operating principle was detailed and technical indications for the flowmeter correct design were provided. For validation purposes, the flow rate measurements taken at the inlet of a Multijet Common Rail (CR) injector were compared to the theoretical data predicted by an advanced numerical model of the complete fuel injection system. The developed flowmeter was then applied to characterize the flow rate ripple at the delivery of the CR high-pressure reciprocating pump.

A Model to Predict the Characteristics of Fires Following the Rupture of Natural Gas Transmission Pipelines

The gas industry has an excellent safety record in operating high pressure transmission pipelines. Nevertheless, it is important that pipeline operators have an understanding of the possible consequences of an accidental gas release, which may ignite, in order to help manage the risks involved and to develop appropriate standards and design codes for pipeline operations. The most serious type of hypothetical incident that could affect a high pressure gas transmission pipeline, involves a full pipe rupture. This paper describes the extension and validation of a physically-based phenomenological model of jet fires for predicting the size and position of the fires resulting from underground gas pipeline ruptures and to predict thermal radiation levels around such fires. The application of the complete model to underground pipeline ruptures has been made possible by the development of a crater source sub-model which provides suitable input parameters to the fire structure calculation. Predictions of the complete model have been compared with the results from two full-scale pipeline rupture tests, which has demonstrated the performance of the model for a range of realistic scenarios. The work was undertaken by an international collaboration of gas companies, as part of a programme of research to obtain information on the consequences of accidental gas releases from transmission pipelines.

Pipeline integrity maintenance using a tethered inspection vehicle (TIV): Lowe, R.; Robson, P. Insight, Vol. 37, No. 6, pp. 413–416 (Jun. 1995)

In recent years there has been a growing awareness of the benefits of using intelligent pigs as a means of maintaining the integrity of pipelines. These pigs are autonomous devices which are transported internally through a pipeline and conduct inspections on-line without the need for taking the pipeline out of operation. This awareness has resulted in the worldwide acceptance of the use of high-resolution on-line inspection equipment for the inspection of high-pressure transmission pipelines. This inspection technology has now been further developed by British Gas for low-pressure pipelines, such as gas and water distribution pipelines, refinery pipelines and even pipelines from the jetty loading point to the terminal. Indeed, discrete sections of decommissioned high-pressure transmission pipelines can also be inspected by this method. This paper describes the tethered inspection vehicle (TIV) as a method of ensuring pipeline integrity, while eliminating unnecessary hydrostatic testing, thereby avoiding the environmental consequences of pipeline failure.