Compendium for the LNG and CNG Practitioner

Frontmatter

1. LNG and Its Thermodynamics

Abstract

LNG is the abbreviation for liquefied natural gas, which in this form belongs to the cryogenic liquefied gases. At the source, i.e. in the gas or oil field, liquefaction from the gas phase takes place with a great deal of energy. From there, it is transported by ship at approx. −161 °C (boiling temperature at atmospheric pressure) to customers in Europe, Japan, China, etc. There, the LNG is temporarily stored in large tank facilities at atmospheric pressure or directly regasified for transport in the gas pipelines. (See [1].)

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2. The Most Important Thermodynamic Processes in the Production, Transport and Storage of LNG

Abstract

The distinctive thermodynamic processes of the are described and explained on the basis of generally known examples.

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3. LNG: From the Source to the End Customer

Abstract

Natural gas is liquefied into LNG at the source using gas liquefaction plants and transported to the hub using LNG tankers. There it is transported to the end customer by road tankers or tank wagons. The process of refuelling the local tank is described in detail, including details of the individual assemblies. The differences between the open and closed hose systems are explained and hazards are pointed out. The method of tank filling is explained and the purpose is explained.

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4. Operational Management

Abstract

LNG, like oil and LPG, is stored in tanks and called up on demand, but the tanks for LNG are vacuum insulated. The call-off can be continuous, even with smaller or larger pauses. As there is no precise definition of discontinuous operation, it shall be assumed that any interruption of LNG offtake longer than 12 h shall be discontinuous.

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5. LNG Applications

Abstract

The economic importance of LNG supply is shown on the basis of statistics and selected possibilities of LNG application are described. These explanations consider the low-pressure area, i.e. gas supply systems with connected consumers, and the high-pressure area with the description of the compression of CNG. The high-pressure area focuses on the use of CNG as a fuel. Assemblies and components are described in detail and avoidable malfunctions are pointed out in terms of safety. Operational considerations and their application are explained and the environmental benefits are elaborated. It may be recognized that ecological solutions are the most economical, as they are always operated in combination.

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6. The Thermodynamic Consideration of the Vacuum Insulated Cryogenic Tank

Abstract

The thermodynamic processes in the tank are described, the tank designs are explained and the requirements for the LNG tank are dealt with in particular. A tabular overview summarizes the following explanations.

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7. Sensor Technology in an LNG Plant

Abstract

It is explained how to connect pressure gauges for recording the total pressure. Furthermore, the special feature of the temperature sensitivity of electronic measuring instruments is discussed. Measuring methods are explained and compared.

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8. Equipment of an LNG Plant

Abstract

LNG plants require additional equipment compared to plants for air gases. The equipment as applicable for air gases and the additional equipment for LNG is described in terms of design and function.

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9. Safety Devices

Abstract

Every pressure vessel must be protected against overpressure. Furthermore, in the case of cryogenic liquefied gases, there is the special feature that their volume increases with increasing boiling pressure due to the decreasing density. The overfill protection excludes overfilling and discharges the product which is produced above the permissible filling level.

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10. Constructive Description of the Hose Couplings for Tank Filling

Abstract

The connection of the tanks with the vehicle tank has an outstanding importance, especially for the safety and for the quality of the product. The connection is made with a hose. At the interface between the hose and the tank is the coupling. This coupling must be used to reliably exclude the ingress of air. Natural gas contaminated with air can cause operating faults and restrict mixed condensation. This cannot be prevented with open refuelling systems.

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11. Insulations

Abstract

There is no such thing as absolute insulation. Different insulation materials and insulation methods are described and special features are pointed out.

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12. Electrical Grounding

Abstract

Earthing provides equipotential bonding between the component and earth so that no sparks or flashovers are possible. It is a protective measure for persons and equipment.

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13. Marked Process Disturbances

Abstract

Typical faults and their consequences in the handling of cryogenic liquefied gases, in particular LNG and CNG, are described and advice is given on how to rectify plant faults.

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14. System Planning

Abstract

It is not only the selected technology that determines the success or failure of an investment but also the correct design. For this purpose, assistance is provided and information on the approval procedure is given. The literature mentioned will be the basis for the approval procedure.

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15. Commissioning and Decommissioning of an LNG Plant

Abstract

The cycles of initial commissioning, commissioning after a longer period of interruption and decommissioning of the plant are explained.

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16. Training Recommendation

Abstract

Product training serves first and foremost to protect the health of employees and to preserve, maintain and care for the objects, apparatus and devices entrusted to them.

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17. Special Instructions and Precautions

Abstract

If the safety regulations are observed, the products LNG and CNG can be traded safely. For this purpose, the relevant regulations are explained and special reference is made to specific protective measures. Damage scenarios are described.

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