Energetic, exergetic, environmental and economic assessment of a novel control system for indirect heaters in natural gas city gate stations

A novel preheating system in pressure reduction stations—natural gas directly flowing inside deep borehole heat exchangers

The application of expansion turbines at natural gas pressure reduction stations (PRS) is considered in order to recover energy contained in the natural gas. This energy is irretrievably lost at the reduction stations which use the traditional pressure reducer. Expanders allow for the electricity production for PRS own needs and for resale. The paper presents an analysis of the possibility of using turboexpanders at PRS in Poland. Authors performed static simulations for the assumed data sets and dynamic simulations for annual data from selected representative natural gas reduction and measurement stations. Energy balances are presented for the discussed scenarios that compare the energy requirements of natural gas pressure reduction stations which use a classic pressure reducer or turboexpander (TE). Using static simulations, authors investigated whether the use of a turboexpander is economically justified for the case if it is used only to supply the reduction station with electricity. Dynamic analyses were carried out using real data. In addition, static analyses were performed for a natural gas reduction and measurement station using a PEM fuel cell for the production of electricity in a combined gas heating system. At higher inlet temperatures and pressures, the expansion process was more economical due to the lower heat power requirement and the greater amount of produced electricity. The PRS with the turboexpander compared to the PRS with the reducer required the supply of thermal energy which did not allow the PRS to lower operating costs for the assumed prices of heat and electricity. The reduction system with the PEM fuel cell in the combined heating system positively achieved lower operating costs of the PRS (without taking into account the investment costs). Total annual costs for PRS with a reducer was PLN 1,593,167.04, and for PRS with TE + PEM PLN 1,430,595.60—the difference was PLN 108,571.44 in favor of the arrangement with TE and PEM. The payback time should be investigated, although the use of such a system gives the impression of oversizing. An increase in the electricity purchase price and a decrease in the natural gas purchase price may contribute to the investment in the future.

Techno-economic assessment of a proposed novel hybrid system for natural gas pressure reduction stations

Energy, exergy, economic and environmental (4E) analysis of using city gate station (CGS) heater waste for power and hydrogen production: A comparative study

This chapter deals with thermodynamic modeling, parametric analysis, and optimization of an integrated system to recover energy from pressure reduction station in city gate station (CGS). This chapter aims to fully cover the thermodynamic modeling of an integrated system consisting of a turbo expander, an organic Rankine cycle (ORC) and a proton exchange membrane (PEM) electrolyzer to produce and store hydrogen. The pressure of natural gas in transmission pipeline in Iran gas system is high which sometimes go beyond 7 MPa. This pressure needs to be reduced near the cities pipeline pressure to 1.7 MPa. This pressure reduction results in ample potential to recover energy to generate electricity. In the proposed integrated system in this chapter, a comprehensive parametric analysis including the effect of main parameters such as natural gas preheat temperature, the natural gas pressure inlet to turbo expander, the heater mass fuel flow rate, and high temperature of ORC on the system performance is investigated.

The United States relies on natural gas for one-quarter of its energy needs. In 2001 alone, the nation consumed 21.5 trillion cubic feet of natural gas. A large portion of natural gas pipeline capacity within the United States is directed from major production areas in Texas and Louisiana, Wyoming, and other states to markets in the western, eastern, and midwestern regions of the country. In the past 10 years, increasing levels of gas from Canada have also been brought into these markets (EIA 2007). The United States has several major natural gas production basins and an extensive natural gas pipeline network, with almost 95% of U.S. natural gas imports coming from Canada. At present, the gas pipeline infrastructure is more developed between Canada and the United States than between Mexico and the United States. Gas flows from Canada to the United States through several major pipelines feeding U.S. markets in the Midwest, Northeast, Pacific Northwest, and California. Some key examples are the Alliance Pipeline, the Northern Border Pipeline, the Maritimes & Northeast Pipeline, the TransCanada Pipeline System, and Westcoast Energy pipelines. Major connections join Texas and northeastern Mexico, with additional connections to Arizona and between California and Baja California, Mexicomore » (INGAA 2007). Of the natural gas consumed in the United States, 85% is produced domestically. Figure 1.1-1 shows the complex North American natural gas network. The pipeline transmission system--the 'interstate highway' for natural gas--consists of 180,000 miles of high-strength steel pipe varying in diameter, normally between 30 and 36 inches in diameter. The primary function of the transmission pipeline company is to move huge amounts of natural gas thousands of miles from producing regions to local natural gas utility delivery points. These delivery points, called 'city gate stations', are usually owned by distribution companies, although some are owned by transmission companies. Compressor stations at required distances boost the pressure that is lost through friction as the gas moves through the steel pipes (EPA 2000). The natural gas system is generally described in terms of production, processing and purification, transmission and storage, and distribution (NaturalGas.org 2004b). Figure 1.1-2 shows a schematic of the system through transmission. This report focuses on the transmission pipeline, compressor stations, and city gates.« less

Energy and exergy analysis and multi-objective optimization of using combined vortex tube-photovoltaic/thermal system in city gate stations

An experimental investigation on using heat pipe heat exchanger to improve energy performance in gas city gate station

Research on multi-energy coupled preheating system of city gate station based on Modelica simulation

The energy sector was responsible for approximately 84% of carbon dioxide equivalent (CO2e) greenhouse gas (GHG) emissions in the U.S. in 2012 (EPA 2014a). Methane is the second most important GHG, contributing 9% of total U.S. CO2e emissions. A large portion of those methane emissions result from energy production and use; the natural gas, coal, and oil industries produce approximately 39% of anthropogenic methane emissions in the U.S. As a result, fossil-fuel systems have been consistently identified as high priority sectors to contribute to U.S. GHG reduction goals (White House 2015). Only two studies have recently attempted to quantify the abatement potential and cost associated with the breadth of opportunities to reduce GHG emissions within natural gas, oil, and coal supply chains in the United States, namely the U.S. Environmental Protection Agency (EPA) (2013a) and ICF (2014). EPA, in its 2013 analysis, estimated the marginal cost of abatement for non-CO2 GHG emissions from the natural gas, oil, and coal supply chains for multiple regions globally, including the United States. Building on this work, ICF International (ICF) (2014) provided an update and re-analysis of the potential opportunities in U.S. natural gas and oil systems. In this report we synthesize these previously more » published estimates as well as incorporate additional data provided by ICF to provide a comprehensive national analysis of methane abatement opportunities and their associated costs across the natural gas, oil, and coal supply chains. Results are presented as a suite of marginal abatement cost curves (MACCs), which depict the total potential and cost of reducing emissions through different abatement measures. We report results by sector (natural gas, oil, and coal) and by supply chain segment - production, gathering and boosting, processing, transmission and storage, or distribution - to facilitate identification of which sectors and supply chain segments provide the greatest opportunities for low cost abatement. « less

Natural gas stream must be preheated before pressure reduction takes place at natural gas pressure reduction station (PRS). It ensures that the natural gas stream remains above hydrate-formation zone. Heaters are used to prevent this problem. There is no precise method for determining the adjustment points of heaters; and the gas is usually heated to a temperature higher than the required temperature leading to the energy loss in heaters. In the present paper, the outlet gas temperature of regulator was predicted to prevent the energy dissipation by an applied analysis through thermodynamics equations and considering the deviation of natural gas from the ideal gas state using MATLAB software. The prediction of outlet temperature and application of control mechanisms made the temperature close to the standard temperature, so that avoiding the formation of destructive hydrate phenomenon, prevented the dissipation of 7983.7 standard cubic meter of natural gas and reduced 15.29 tone greenhouse gas emissions in a year at the PRS under study. The economic analysis of the proposed system has been carried out using Payback ratio method. The payback period of implementation of this control system is only less than one year. Results of comparison between the measured output temperature and calculated temperature through the software indicated an average difference of 9%.

Application of water reheating system for waste heat recovery in NG pressure reduction stations, with experimental verification

Preheating is often required to prevent hydrate formation during the pressure reduction process in a natural gas distribution network’s pressure reduction station. This paper examines an energy recovery method to avoid the cost and energy consumption of this preheating. The primary aim is to assess the techno-economic feasibility of an energy recovery system based on the Ranque–Hilsch vortex tube coupled to a heat exchanger for large-scale application to the gas grid. To this end, a techno-economic model of the entire energy recovery system was included in an optimisation procedure. The resulting design minimises the payback period (PP) when the system is applied to the pressure reduction stations belonging to a particular gas grid. The pressure reduction stations always operate at an outlet pressure above atmospheric pressure. However, available performance models for the Ranque–Hilsch vortex tube do not permit prediction at backpressure operation. Therefore, a novel empirical model of the device is proposed, and a cost function derived from several manufacturer quotations is introduced for the first time, to evaluate the price of the Ranque–Hilsch vortex tubes. Finally, a nearly complete set of pressure reduction stations belonging to the Italian natural gas grid was chosen as a case study using actual operating parameters collected by each station’s grid manager. The results indicate that the environmental temperature strongly affects the technical and economic feasibility of the proposed energy recovery system. In general, pressure reduction stations operating at an ambient temperature above 0 °C are economically desirable candidates. In addition, the higher the energy recovery system convenience, the higher the flow rate and pressure drop managed by the station. In the Italian case study, 95% of preheating costs could be eliminated with a PP of fewer than 20 years. A 40% preheating cost saving is still possible if the maximum PP is limited to 10 years, and a small but non-negligible 3% of preheating costs could be eliminated with a PP of fewer than 4.5 years.

In spite of all the efforts in different industries to reduce the number of undesirable accidents, a lot of events always threat industrial societies. These events often cause huge damages to the environment, facilities and even in some cases, fatalities and disabilities for people. Therefore, it is important to predict these probable accidents and plan to prevent them. Hence, this research proposed to analysis hazards in one of the most important components of natural gas distribution network which is city gate station (C.G.S). In this analysis firstly, critical hazards are identified and classified based on HSE standards. Then for decreasing risk of selected hazards, a survey is done on a specific C.G.S according to previous accidents. Finally, some suggestions are offered to improve existing preventive activities.

Natural gas is transported from production sites to end users through high pressure (5-7 MPa) transmission pipelines. At a consumption point or when passing into a lower pressure pipeline, the pressure of the gas must be reduced. This pressure reduction takes place at City Gate Stations (CGS). Currently in all of Iran's CGSs, valuable pressure exergy (potential energy) contained by the high-pressure natural gas is lost to the environment in throttling valves (expansion valves). In this study, based on a comprehensive program, the inlet and outlet properties and daily flow rates of natural gas through Khorasan province (Iran) CGSs were measured and recorded for a whole year. Based on these data, the amount of energy lost to the environment was calculated. It was found that the yearly average mass flow rate in Khorasan CGSs is 90.5 kg/s, and average energy destruction is 13,240 kW. Assuming a conversion efficiency of 75%, one can extract 9,930 kW of electrical power. Based on Iran's average daily natural gas consumption of 336 × 106 m3/day and assuming the same conditions at all CGSs as at Khorasan, 762 MW of electrical power could be generated by capturing the lost pressure exergy flowing through all of Iran's CGSs.