What is the operation of the distribution system for natural gas?
Natural gas pipelines are the lifeblood of oil and gas companies, spanning many thousands of miles carrying oil from the source to the consumer. In this post, we will delve into the question – of how do natural gas pipeline distribution system work? The entire gas pipeline system is divided into three sections.
First, the pipes which carry raw natural gas from the wellheads to the processing units are usually small in diameter, and low-pressure natural gas pipelines are called the gathering system.
From these refineries and processing units, gas transmission pipelines carry the products to city gate stations from where distribution lines reach gas to household and commercial consumers.
Hydrogen transportation by pipelines
Gaseous hydrogen is one of the oil and natural gas industry products. Vast networks of gas pipelines are needed to transport it to large-scale consumers of hydrogen gas. Setting up new pipelines can be very expensive, so companies seek to transport gaseous hydrogen using existing pipelines. This poses some technical challenges. Hydrogen tends to make the pipeline steel brittle over some time. Effective and low-cost hydrogen compression technology is needed for the proper gas transmission, and safety must be ensured by controlling leaks and permeation.
The blending of Hydrogen in Natural Gas Pipelines
One solution to these challenges is Fiber Reinforced Polymer (FRP) pipelines. This ensures strong and safe piping and is also approximately 20% lower in the cost of setup. In addition, FRP pipelines are available in more extended units, reducing the total cost of welding across a given pipeline length. The other solution deployed involves using existing natural gas pipelines to transport a blend of hydrogen and natural gas. This mix typically constitutes about 15% of hydrogen and entails only minor pipeline infrastructure adaptations.
The entire gas pipeline operations include compressor stations, pipelines, valves, and meter stations.
Compressor stations provide the energy to push the gas through the pipes with the required pressure and flow rate. The length of this pipeline could be anywhere between forty and a hundred miles. Metering Stations perform the function of monitoring the flow of gas through the pipelines. Valves are also essential components in the pipeline system. They help regulate and restrict flow, primarily when repairs and maintenance work is conducted on a specific section of the pipeline.
Desulfurization for Fuel Cells
Fuel cells help produce clean, efficient energy. They do this by producing electricity using hydrogen or synthesis. However, the gas used in fuel cells needs to be pure and free of contaminants like sulfur. Sulfur occurs in natural gas in forms such as Hydrogen Sulphide, Sulfur Oxides, Carbonyl Sulfide, etc.
Desulfurization of gasoline can also be carried out in the gas phase by reactive adsorption or passive absorption. Desulfurization is the process by which these sulfur compounds are removed from the fuel for use in fuel cells so they can provide clean energy.
The Role of Fuel Cells and Hydrogen in Stationary Applications
Stationary fuel cells power homes, businesses, and even vehicles. Also, these cells generate electricity rather than combustion and are hence preferred as a vital source of clean energy. They also benefit from providing power onsite and directly to consumers; there is no loss of control over a long transmission grid. They also produce less carbon dioxide. As a result, more and more utility companies are adopting stationary fuel cells to achieve environmental compliance.
Natural Gas Pipelines in the United States
The U.S. boasts a massive network of over 2 million miles of natural gas distribution pipelines and about 321,000 miles of gas transmission and gathering pipelines.
Both federal and state agencies regulate this extensive network. The Federal Energy Regulatory Commission (FERC) and the U.S. Department of Transportation (DOT) oversee interstate pipelines. The Federal Energy Regulatory Commission regulates interstate natural gas transportation, facility construction, and storage facilities for natural gas.
One of the key parameters that have a bearing on the safety and efficiency of oil and gas companies in the optimal gas transmission process across the many miles from production units to consumers.
Steady-State or Non-steady State
Companies measure and monitor this gas transmission through detailed tracking of the flow in the pipelines. When the flow is such that the pressure upstream and downstream and the gas flow rate are constant and stable, it is known as steady-state. However, when this is not the case, and these readings fluctuate, it is considered a non-steady state. Therefore, companies strive to manage the compressors to produce the optimal pressure and flow without consuming too much power.
Transient Flow in Gas Transmission Pipelines
The non-steady-state of flow is also known as transient flow, where the velocity and pressure change from time to time. This can occur either because of operational interventions like open or closed valves, pumps being started or stopped, or the optimum compressor pressure has not been achieved. Conversely, a steady-state helps companies achieve optimum gas transmission metrics for efficiency and economy.
Various factors determine pipeline economics. These include gas sourcing and production costs, gas sales volume and prices, and pipeline operating costs. Therefore, companies need to balance several parameters to achieve economic viability. For instance, delivering the maximum possible gas may seem beneficial in the shortest period may seem helpful. But this can happen at a very high cost because compressors use too much energy to do this. In other words, the economic gain of a faster supply of gas to consumers is offset by the high cost of transmission.
Optimization in Natural Gas Network Planning
This, among several other factors, makes the planning of the natural gas pipeline distribution system is very complex and challenging. It combines several disciplines such as engineering, financial planning, risk analysis, environmental factors, operations research, technology, regulatory compliance, etc. Good natural gas network planning requires considering all the infrastructure, processes, systems, materials, storage, transportation, and people involved.
Underground Sensing Strategies for the Health Assessment of Buried Pipelines
Pipeline management involves rigorous and regular monitoring to ensure the system’s health underground. Risks like Permanent Ground Displacement (PGD), often caused by landslides or disruptions from earthquakes, can pose serious problems and risks. Other defects can develop from leaks, corrosion, wear, or rust. Companies use embedded monitoring systems in and around the pipeline to track the health of the infrastructure. Wireless telemetry using wireless sensors is also used to improve the efficacy and lower the cost of monitoring PGD. Other techniques include monitoring joint rotations using potentiometers and damage assessments using acoustic emission and conductive surface sensors, etc.
In this post, we have looked at the natural gas pipeline system, its components, and some of the vital elements involved in the natural gas distribution system. And as we have seen, several complex processes must come together seamlessly to ensure the smooth management of this extensive network of natural gas pipelines.