Gas Distribution System Research Articles

Towards Port-Hamiltonian Modeling of Multi-Carrier Energy Systems: A Case Study for a Coupled Electricity and Gas Distribution System

Multi-carrier energy systems have been identified as a major concept for future energy supply. For their operation, model-based control methods are necessary whose design requires modular, multi-physical control-oriented models. In literature, there exists no control design model which combines the variables of the networks and system dynamics that go beyond ideal storage elements. Port-Hamiltonian systems represent a promising approach for the scalable modeling and control of multi-carrier energy systems. In this publication we present a case study which illustrates the port-Hamiltonian modeling of an exemplary coupled electricity and gas distribution system. Simulations indicate the plausibility of the presented model.

Prospects for development of heat supply systems in high-rise districts

The article analyzes the main advantages and disadvantages of centralized and decentralized heat supply systems in high-rise districts. The main schemes of centralized heat supply systems are considered. They include centralized heat supply from boiler houses, centralized heat supply from autonomous heat sources, heat supply from roof boiler houses and door-to-door heating supply. For each of these variant, the gas distribution systems are considered and analyzed. These systems vary depending on the heat source location. For each of these systems, technical and economic indicators are taken into account, the analysis of which allows choosing the best option for districts where high-rise buildings predominate.

The main directions of increasing the reliability of gas distribution systems in high-rise districts

The main source of energy in the economy is gas fuel. The specific weight of natural gas in the fuel and energy balance is about 50%. †The main requirement for the gas distribution system is to ensure the reliability, safety of this system. One of the ways to improve the reliability of gas supply systems is to use the reliability of automatic equipment to determine the gas contamination of premises. Based on the analysis of calculation formulas, an algorithm for the hydraulic calculation of gas pipelines is compiled. Based on the characteristics of gas distribution systems, it is advisable to apply such a solution, when gas supply of domestic consumers, boiler houses of municipal agricultural enterprises is carried out from the distribution network of high and medium pressure through autonomous combined pressure regulators installed in areas of high-rise buildings.

Methodical approach to determination of costs at the initial stages of the project research of gas-supply systems

The article deals with topical issues at the pre-investment stage of project design to justify decisions on the feasibility of further investment and the transition to the next stage of design - the development of project documentation. At the pre-project stage, there is often a situation when the parameters of structures have not yet been determined, and capital investments must be evaluated. Methodological approaches to determining the cost of gasification facilities and the estimated model of cost calculations at the stage of investment justification with the help of enlarged indicators that improve the accuracy and validity of calculations at the stage of pre-design studies are substantiated. It is shown that the enlarged indicators used at the stage of investment justification form the regulatory basis for determining the cost of gasification facilities, for estimating capital costs, as well as for evaluating the effectiveness of investments in the selection of project options. The object of the study adopted electrically welded steel pipes and polyethylene pipes for gas pipelines. Evaluation and forecasting of the cost of gas distribution systems in the article are proposed using regression models depending on time and diameter of the pipe. The regression dependences of the cost of steel and polyethylene pipes of all standard sizes and confidence intervals for the cost of pipes allow to estimate also possible errors of the forecast cost estimation.

Determination of high-pressure pipeline cyclization degree with exploratory technique

The article examines the issues of determining the network configuration, which ensures the maximum reliability of the gas distribution system. Rationally designed configuration of the gas distribution network with the adopted gas supply scheme can provide reliable operation for a long time. Results are recommended to be used in the design of gas distribution networks, as well as in determining the reserve for improving the reliability of the network for the adopted gas supply scheme for users.

Risk Assessment for Urban Gas Transmission and Distribution System Using Fuzzy Comprehensive Evaluation Method

AbstractUrban gas transmission and distribution system mainly consists of three subsystems: storage station, gas network, and users. The subsystem fault trees are established on the basis of the in...

A real option assessment of flexibilities in the integrated planning of natural gas distribution network and distributed natural gas-fired power generations

There is an increasing integration of distributed natural gas-fired electric power generations across the globe. The natural gas-fired power generators are dependent on the availability of reliable natural gas distribution systems. This interdependency coupled with the scalability of the natural gas-fired distributed power generators presents the management of an energy utility with real options to execute, delay or abandon long-term expansion plans based on new realities of electric power demand. A real options analysis of these flexibilities is carried out in this paper. The assessment of these options includes the identification and valuation of the identified options. The value of flexibilities and options is illustrated by assessing the options to implement, delay or abandon expansion plans in the presence of uncertain electric power demand on 9 and 33 bus electricity distribution systems.

Thermodynamic analysis of a novel pumped thermal energy storage system utilizing ambient thermal energy and LNG cold energy

Pumped thermal energy storage (PTES) has become a hot topic on large scale energy storage technology because of the independence on geological conditions and fossil fuels. However, few of the PTES systems have higher round trip efficiencies compared with that of pumped hydro storage except for systems utilizing external heat sources. Furthermore, the used external heat sources are not available everywhere and much additional cost is required for the system integration. As an accessible and cheap heat source, ambient thermal energy is employed in the newly proposed PTES system. LNG (liquid natural gas) cold energy is also used as the heat sink based on possible combination with the natural gas distribution system in the practical operation. The charge process is based on transcritical CO2 heat pump cycle, while cascade design of transcritical CO2 Rankine cycle and subcritical NH3 Rankine cycle is employed in the discharge process. A thermodynamic model is established for energy and exergy analysis as well as the system evaluation. The analysis and evaluation of the optimized baseline case obtained by Genetic Algorithm are then carried out. In addition, the sensitivity of system performance to different variable parameters is also analyzed. Based on the analysis of optimized baseline case, the round trip efficiency can reach 139%. If for 1MW net power output, both of the mass flow rates of CO2 and NH3 are 7.4kg/s with LNG mass flow rate of 14.8kg/s. Because of much higher round trip efficiency compared with other large scale energy storage systems, the proposed system is promising for future development and applications.

Chemical Stability of La 1-X Sr x Mn0.8Ni0.2O3-δ x={0.1 to 0.5} Cathode Compositions with 8YSZ at High Temperature

INTRODUCTION : A one-step co-sintered solid oxide fuel cell (SOFC) stack consists of several cells sintered at high temperature at once (>1250oC). Typically, each SOFC cell is composed of a cathode (strontium-doped lanthanum manganite, LSM), an electrolyte (8YSZ), an anode (NiO/8YSZ), a ceramic interconnector and a dedicated gas distribution system [1]. It is believed that reducing the step processing should lead to cost reduction of SOFC cells fabrication and finally promote a wider use of SOFC devices. Unfortunately, several technological issues still have not had an adequate solution, mainly: thermal expansion mismatch between stack components [2] and lack of efficiency caused by formation of a high electrical resistance secondary phase at the LSM/8YSZ interface, La2Zr2O7 (LZO) or SrZrO3 (SZO) [3]. Several methods have been evaluated for reducing secondary phase formation, for instance: protector buffer layer [4], Ce addition into LSM structure [5] and A-site deficiency LSM compositions [6], etc. However, they show a limited performance or are complicated to use at the temperatures required for fabricating a one-step co-sintered SOFC stack. This work evaluates the impact of a Ni-addition, into B-site of LSM composition, on the formation of secondary phase at the LSM/8YSZ interface. Equal Ni addition (20 at%) was used in several LSM compositions, with different strontium contents, and their chemical stability with 8YSZ at 1300oC was evaluated. Moreover, a chemical stability comparison between a commercial LSM composition (La0.8Sr0.2MnO3-δ) and a similar Ni-added one (La0.8Sr0.2Mn0.8Ni0.2O3-δ) is presented. EXPERIMENTAL: La1-xSrxMn0.8Ni0.2O3-δ with x={0.1 to 0.5} compositions, hereinafter called Ni-added LSM, were fabricated by a glycine route using nitrates as reactive and glycine as fuel. Both, reactive and glycine, were dissolved in deionized water at room temperature until obtain a clear solution. Water and organic components were removed by different heat treatment at 180oC and 450oC, respectively. Afterwards, all powders were reacted and calcinated at 850oC and 1000oC for 5h, respectively. Chemical reaction with 8YSZ was evaluated by mixing Ni-added LSM powders with 8YSZ in 50/50 wt%. All samples, whatever 8YSZ mixed or not, were sintered at 1300oC for 5h. Electrical conductivity measurements were performed by using four-probe method from room temperature to 800oC in air, while chemical stability with 8YSZ was evaluated by x-ray diffraction (XRD). RESULTS AND DISCUSSION: XRD patterns from Ni-added LSM compositions showed no secondary phase formation after sintered at 1300oC for 5h (not shown). Ni-added LSM compositions with low strontium content (x≤0.3) were indexed as rhombohedral crystal structure, while at higher strontium contents (x>0.3) an orthorhombic crystal structure tends to gradually form instead of the rhombohedral one, thus at x=0.5 only orthorhombic crystal structure was indexed. Electric conductivity of La1-xSrxMn0.8Ni0.2O3-δ with x={0.1 to 0.5} compositions have a maximum (115 S cm-1) at x=0.3, well correlated with the crystal structure evolution as a function of strontium content. (not shown) Fig.1 shows XRD patterns from Ni-added LSM compositions after mixing with 8YSZ (50/50 wt%) sintered at 1300oC for 5h. No crystal structure change was observed respect to non 8YSZ mixed condition. However, at strontium contents over x≥ 0.3 a secondary phase (SZO) was observed, while below x<0.3 no secondary phase was observed. In addition, XRD patterns from a commercial La0.8Sr0.2MnO3-δ and La0.8Sr0.2Mn0.8Ni0.2O3-δ compositions mixed with 8YSZ and sintered at 1300oC for 5h were recorded. LZO secondary phase was observed only in commercial LSM composition, while it was not observed in La0.8Sr0.2Mn0.8Ni0.2O3-δ composition, even after sintering at 1300oC for 24h (not shown) Results suggest that Ni addition into the B-site of LSM (with low strontium content), could be a suitable and simple method for reducing, and eventually suppressing, the secondary phase formation at the LSM/8YSZ interface at high temperature. [1] S. Suda, J. P. Wiff and S. Shimada, ECS Trans. 57(1), 543-548 (2013) [2] B. Ahmed, S. B. Lee, R. H. Song, J. W. Lee, T. H. Lim and S. J. Park, ECS Trans. 57, 2075-2082 (2013) [3] C. Levy, Y. Zhong, C. Morel and S. Marlin, ECS Trans. 25, 2815-2823 (2009) [4] H. S. Noh, J. W. Son, H. Lee, H. R. Kim, J. H. Lee and H. W. Lee, J. Korean Ceram. Soc. 47, 75-81 (2010) [5] J. P. Wiff, K. Jono, M. Suzuki and S. Suda, J. Power Sources 196(15) 6196-6200 (2011) [6] A. Chen, J. R. Smith, K. L. Duncan, R. T. DeHoff, K. S. Jones and E. D. Wachsman, J. Electrochem. Soc. 157, B1624-B1628 (2010) Figure 1

SOME ASPECTS OF PREVENTION OF CRYSTALLINE HYDRATES FORMATION AT GAS DISTRIBUTION STATIONS

The existing methods for natural gas dehydration both in fields and at compressor stations cannot always provide standatdized values of natural gas dehydration. The analysis of operation of gas distribution systems shows that dehydration units are improperly placed and are often installed out of condensation and freezing zones. This is due to the lack of consideration of phase transitions impact in gas throttling on its temperature condition. Due to insufficient natural gas dehydration, crystalline hydrates can be formed on wellbores, distribution lines and main gas pipelines and at its reduction, disturbing the operation of the equipment of compressor stations, gas distribution stations, deranging instrumentation and automation. The issues of reliability of gas pipeline systems considering the formation of crystalline hydrate plugs in pipelines have been studied. The analysis of the methods and devices preventing hydrates formation and eliminating existing crystalline hydrate plugs has shown that to provide normalized parameters of the transported gas it is necessary to perform additional water vapor, condensate drops and crystalline hydrate particles removal from natural gas at gas distribution stations during winter months. Currently applied methods used to deal with crystalline hydrate plugs in main gas pipelines require significant expenses and do not effectively ensure the reliability of pipelines operation. An energy-efficient design of an integrated treatment unit which provides an additional natural gas treatment at GDS, increases the reliability of gas pipelines protection against hydrate blockage and improves the efficiency of gas supply systems as a whole have been proposed at the Department of Heat and Gas Supply and Ventilation of the SWSU.

Experimental investigation on explosion flame propagation of H2-O2 in a small scale pipeline

The flame propagation law of H2 and O2 premixed gas explosion was studied in a small-scale pipeline experiment with a full size transparent window set up. The experiment consists of a small-scale blast pipe, gas distribution system, ignition system, pressure data acquisition system, high-speed photography system and so on. By setting different conditions of initial concentration and initial pressure, the flame propagation law was studied. Flame propagation images were obtained through a high-speed photography collection system and analyzed for its propagation law. The explosion flame propagation speed was calculated through image processing by MATLAB. The results show that under the condition of the same initial concentration, the higher the initial pressure, the larger the explosion flame acceleration. The maximum explosion pressure has approximate linear relationship to the initial pressure. Under the same initial pressure; when the equivalent ratio is closer to 1, the flame acceleration rate becomes larger, and the explosion pressure reaches the maximum value.

A chance constrained programming approach to integrated planning of distributed power generation and natural gas network

The growing integration of distributed electric power generators means the reliability of electricity distribution systems will increasingly depend on the reliability of primary energy resources such as natural gas supply for natural gas-fired distributed power generation. This, therefore, necessitates an integrated approach for planning both the electricity and natural gas distribution systems for the purpose of ensuring reliable natural gas supply for electricity generation. We propose a probabilistic planning approach based on the chance constrained programming method for planning these two systems in the presence of uncertain real and reactive power demand. The proposed model minimizes the investment cost of gas-fired generators, natural gas pipeline and the operation cost of the natural gas-fired distributed generators over a long-term planning horizon. The proposed integrated planning approach is used to develop a 10 years long-term plan for 9 and 33 bus distribution systems. The result shows that the integrated planning approach results in a cheaper and more reliable system in comparison with a traditional sequential planning approach.

Strategy selection model for development of natural gas distribution systems based on AHP/DEA methodologies

Strategy selection model for development of natural gas distribution systems based on AHP/DEA methodologies

Locate Fugitive Methane Emission from Compressor Station of Natural Gas Transmission and Distribution System for Reducing Environmental Risk

Locate Fugitive Methane Emission from Compressor Station of Natural Gas Transmission and Distribution System for Reducing Environmental Risk

Locate Fugitive Methane Emission from Compressor Station of Natural Gas Transmission and Distribution System for Reducing Environmental Risk

Locate Fugitive Methane Emission from Compressor Station of Natural Gas Transmission and Distribution System for Reducing Environmental Risk

Economic model predictive inventory routing and control

The paper proposes an economic model predictive control (EMPC) strategy for the inventory routing problem under demand uncertainty. The strategy is illustrated using an application on industrial gas distribution systems, where the product is transported to customers in small tanks and the inventory levels at the customers’ sites are monitored and controlled by the supplier following a vendor managed inventory approach. The objective is to produce balanced decisions for the joint routing and the inventory control problem over the planning horizon with respect to the decision maker’s perspective against stock-out risk. The proposed EMPC strategy makes use of a mixed integer mathematical programming optimization model that describes the deterministic inventory routing problem with simultaneous pickups and deliveries over a specific planning horizon. A time series decomposition forecasting model is used for predicting future demand and an exact linearization of the quadratic term of the objective function guarantees optimality of the solutions. The proposed methodology is illustrated using two examples featuring a single distribution centre, and three customers with simple and complex demand profiles. It is shown that EMPC offers a useful tool for producing balanced decisions between transportation and inventory costs and tracking of the safety inventory levels.

Mitigation of methane emissions in a pilot-scale biocover system at the AV Miljø Landfill, Denmark: 2. Methane oxidation

Greenhouse gas mitigation at landfills by methane (CH4) oxidation in engineered biocover systems is believed to be a cost effective technology but so far a full quantitative evaluation of the efficiency of the technology in full scale has only been carried out in a few cases. A third generation semi-passive biocover system was constructed at the AV Miljø Landfill, Denmark. The biocover was fed by landfill gas pumped out of three leachate collection wells. An innovative gas distribution system was used to overcome the often observed uneven gas distribution to the active CH4 oxidation layer resulting in overloaded areas causing CH4 emission hot spot areas in the biocover surface. The whole biocover CH4 oxidation efficiency was determined by measuring the CH4 inlet load and CH4 surface fluxes. In addition, CH4 oxidation was determined for single points in the biocover using two different methods; the carbon mass balance method (based on CH4 and carbon dioxide (CO2) concentrations in the deeper part of the cover and CH4 and CO2 surface flux measurements) and a new-developed tracer gas mass balance method (based on CH4 and tracer inlet fluxes and CH4 and tracer surface flux measurements). Overall, the CH4 oxidation efficiency of the whole biocover varied between 81 and 100% and showed that the pilot plant biocover system installed at AV Miljø landfill was very efficient in oxidizing the landfill CH4. The average CH4 oxidation rate measured at nine campaigns was approximately 13gm−2d−1. Extrapolating laboratory measured CH4 oxidation rates to the field showed that the biocover system had a much larger CH4 oxidation potential in comparison to the tested CH4 load. The carbon mass balance approach compared reasonably well with the tracer gas mass balance approach when applied for quantification of CH4 oxidation in single points at the biofilter giving CH4 oxidation efficiencies in the range of 84 to a 100%. CH4 oxidation rates where however much higher using the tracer gas balance method giving CH4 oxidation rates between 7 and 124gm2d−1 compared to the carbon mass balance, which gave CH4 oxidation rates −0.06 and 40gm2d−1. The study also revealed that the compost respiration contributed significantly to the measured CO2 surface emission, and that the contribution of the compost respiration decreased significantly with time probably due to further maturation of the compost material.

Mitigation of methane emissions in a pilot-scale biocover system at the AV Miljø Landfill, Denmark: 1. System design and gas distribution

Greenhouse gas mitigation at landfills by methane oxidation in engineered biocover systems is believed to be a cost effective technology, but so far a full quantitative evaluation of the efficiency of the technology in full scale has only been carried out in a few cases. A third generation semi-passive biocover system was constructed at the AV Miljø Landfill, Denmark. The biocover system was fed by landfill gas pumped out of three leachate collection wells. An innovative gas distribution system was used to overcome the commonly observed surface emission hot spot areas resulting from an uneven gas distribution to the active methane oxidation layer, leading to areas with methane overloading. Performed screening of methane and carbon dioxide surface concentrations, as well as flux measurement using a flux chamber at the surface of the biocover, showed homogenous distributions indicating an even gas distribution. This was supported by results from a tracer gas test where the compound HFC-134a was added to the gas inlet over an adequately long time period to obtain tracer gas stationarity in the whole biocover system. Studies of the tracer gas movement within the biocover system showed a very even gas distribution in gas probes installed in the gas distribution layer. Also the flux of tracer gas out of the biocover surface, as measured by flux chamber technique, showed a spatially even distribution.Installed probes logging the temperature and moisture content of the methane oxidation layer at different depths showed elevated temperatures in the layer with temperature differences to the ambient temperature in the range of 25–50°C at the deepest measuring point due to the microbial processes occurring in the layer. The moisture measurements showed that infiltrating precipitation was efficiently drained away from the methane oxidation layer.

Colfax Corporation: Designing a Middle East Oil and Gas Distribution System

Colfax Corporation was a young, privately held collection of pump-manufacturing companies from the United States and Europe. Intending to go public, it was eager to find a story for investors of how it could grow at rates faster than its subsidiaries had historically grown in their home regions and core-customer industrial markets. This case describes a singular new-growth opportunity: selling Colfax solutions into state-owned petroleum enterprises in the Middle East at a time when these producers were straining to add capacity. Designing the optimal marketing system required Colfax to weigh a complex of issues, including global resource allocation and deployment, a process for customer-relationship building, and estimates for revenue streams versus investment outlays. The design process was, in short, far more than “sticking sales rep pins in the map.” Case readers are asked to think along with the Colfax global management team in deciding, “How much can we afford to risk our current income model in order to build new capacity in a new region in a new way?”Understanding issues related to global B2B marketing channel strategy development, as well as complexities of entering unfamiliar new international markets such as Middle East oil and gas.

Optimal Expansion Co-Planning of Reconfigurable Electricity and Natural Gas Distribution Systems Incorporating Energy Hubs

In a carbon-constrained world, natural gas with low emission intensity plays an important role in the energy consumption area. Energy consumers and distribution networks are linked via energy hubs. Meanwhile, reconfiguration that optimizes operational performance while maintaining a radial network topology is a worldwide technique in the electricity distribution system. To improve the overall efficiency of energy infrastructure, the expansion of electricity distribution lines and elements within energy hubs should be co-planned. In this paper, the co-planning process is modeled as a mixed integer quadratic programming problem to handle conflicting objectives simultaneously. We propose a novel model to identify the optimal co-expansion plan in terms of total cost. Operational factors including energy storages and reconfiguration are considered within the systems to serve electricity, cooling and heating loads. Reconfiguration and elements in energy hubs can avoid or defer new elements’ installation to minimize the investment cost, maintenance cost, operation cost, and interruption cost in the planning horizon. The proposed co-planning approach is verified on 3 and 12-node electricity and natural gas distribution systems coupled via energy hubs. Numerical results show the ability of our proposed expansion co-planning approach based on energy hub in meeting energy demand.