Gas Dehydration Field Manual

Maurice Stewart, Ken Arnold

• Publisher: Gulf Professional Publishing
• Year: 2011
• ISBN:
  9781856179812
• Topic: Physical Sciences
• Subtopic: Fluid Mechanics

Gas Dehydration Field Manual presents different methods of gas dehydration, focusing on the differences between adsorption and absorption. It discusses the various designs and operations in a gas processing facility. As an introduction, the book provides different concepts and theories that describe the gas processing industry. It then discusses the processes involved in the gas processing industry, which include absorption, adsorption, glycol regeneration, glycol filtration, and carbon purification. The book is divided into three parts. The first part discusses some of the basic terms and concepts of gas dehydration. The second part focuses on the factors involved in the different gas-dehydration methods. It also describes the difference between absorption and adsorption, as well as the process involved in glycol dehydration. The last part of the book discusses the proper care, maintenance, and troubleshooting methods of glycol dehydration process. This book is mainly designed for engineers, technologists, and operating personnel in the gas processing industry. Aside from engineers and process designers, readers who are interested in the different processes involved in gas dehydration will find this book a useful guide and reference.

• Include hydrate prevention, chemical injection systems, hydrate inhibitor methods
• Condensation process, Glycol Regeneration and Molecular Sieves
• An appendix provides the reader with additional exercises and solutions

Part 1. Hydrate Prediction and Prevention

Contents

Objectives1

Overview2

Water content of gas3

Gas hydrates12

Prediction of operating temperature and pressure13

Temperature drop determination15

Hydrate prediction correlations19

Hydrate prevention25

Hydrate inhibition45

Exercises52

Objectives

To prepare natural gas for sale, its undesirable components (water, H₂S and CO₂) must be removed.

Most natural gas contains substantial amounts of water vapor due to the presence of connate water in the reservoir rock.

At reservoir pressure and temperature, gas is saturated with water vapor.

Removal of this water is necessary for sales specifications or cryogenic gas processing.

Primary concerns in surface facilities are determining the:

Water content of the gas

Conditions under which hydrates will form

Liquid water can form hydrates, which are ice-like solids, that can plug flow or decrease throughput.

Predicting the operating temperatures and pressures at which hydrate form and methods of hydrate prevention are discussed in this section.

Overview

Dew Point

The dew point is the temperature and pressure at which the first drop of water vapor condenses into a liquid.

It is used as a means of measuring the water vapor content of natural gas.

As water vapor is removed from the gas stream, the dew point decreases.

Keeping the gas stream above the dew point will prevent hydrates from forming and prevent corrosion from occurring.

Dew Point Depression

Dew point depression is the difference between the original dew point and the dew point achieved after some of the water vapor is removed.

It is used to describe the amount of water needed to be removed from the natural gas to establish a specific water vapor content.

Why Dehydrate?

Dehydration refers to removing water vapor from a gas to lower the stream's dew point.

If water vapor is allowed to remain in the natural gas, it will:

Reduce the efficiency and capacity of a pipeline

Cause corrosion that ...