A new design for natural gas pressure reduction points by employing a turbo expander and a solar heating set

Abstract

a b s t r a c tNatural gas pressure reduction station (CGS) is one of the most important pieces in natural gas transmission system. In a CGS, the high inlet natural gas (NG) pressure has to be reduced down to a much lower value. Pressure reduction is usually implemented by utilizing throttling valves. Due to the positive JouleeThompson coefficient of NG, this pressure drop causes significant temperature fall and consequently hydrate forming in the NG stream. The hydrates may prevent stable NG flow through the pipeline. To prevent hydrate forming, the NG should be preheated by some heaters which burn huge amount of fuel. In this work, firstly, adding a solar heating system aiming to reduce the heater fuel consumption and secondly, replacing the throttling valve by a turbo expander in order to utilize the NG stream exergy are proposed. The proposed configuration is simulated for Birjand CGS as a case study. For the simulation, the locally available solar irradiation is estimated by employing solar engineering formulations and the NG availability is calculated by thermodynamics correlations. Net present value (NPV) method is also employed to analyze the proposed system effectiveness economically, resulting to only 3.5 years of pay back ratio.

A novel method for calculating natural gas density based on Joule Thomson coefficient

“…This task is done by the throttling valve. The heater also warms up the natural gas stream before the pressure reduction process to avoid gas hydrate forming in the natural gas stream [32][33][34].…”

“…This error value in each state could be given by the following equation: For the aim of more professional assessment also, two basic metrics, the MAE (mean absolute error) and STD (standard deviation of absolute error), presented in the following equations, are used to compare and validate the performance of presented correlation [32].…”

Energy Harvesting by a Novel Substitution for Expansion Valves: Special Focus on City Gate Stations of High-Pressure Natural Gas Pipelines

“…Their numerical simulation results, obtained with the commercial proprietary software Honeywell UniSim Design Suite, showed that an operational costs reduction of about 17% can be achieved with respect to thermal-load-tracking control logic. Arabkoohsar et al [23] also proposed a turboexpander and solar heating set to reduce the heater fuel consumption for a new design of NG letdown stations, and thereby, the net present value analysis method would result in 3.5 years of payback ratio for investment period. Ghaebi et al [24] presented a new combination system for energy harvesting from NG letdown stations.…”

Optimization of fuel consumption in natural gas city gate station based on gas hydrate temperature (Case study: Abbas Abad station)

“…Many studies have been accomplished applying solar systems in CGS stations. [6][7][8][9] As an example, Farzaneh-Gord et al 6 studied the feasibility of solar energy for linear heater in the CGS. Their work shows that 100 kWh energy could be saved using this method at the cost of 27,000 USD.…”