Water Hammer Analysis

The most numerous types of fluid machineries are of the pump family (machines which add energy to the fluid), other important types are turbines (which extract energy from fluid). Both types are usually connected to a rotating shaft, hence also called turbomachineries. The prefix turbo- is a Latin word meaning ―spin’’ or ―whirl,’’ appropriate for rotating devices. The pump is the oldest fluid-energy-transfer device known. At least two designs date before Christ: (i) the undershot-bucket waterwheels, or norias, used in Asia and Africa (1000 B.C.) and (ii) Archimedes’ screw pump (250 B.C.), still being manufactured today to handle solid-liquid mixtures or to raise water from the hold of a ship. Paddlewheel turbines were used by the Romans in 70 B.C., and Babylonian windmills date back to 700 B.C. Since that time, many variations and applications of pumps have been developed. The power generating turbomachines (turbines) decrease the head or energy level of the working fluids passing through them and they are coupled to machines, such as electric generators, pumps, compressors etc.

Introduction Compressors are used whenever it is necessary to flow gas from a low-pressure system to a higher-pressure system. Flash gas from low-pressure vessels used for multi-stage stabilization of liquids, oil treating, water treating, etc.; often exists at too low a pressure to flow into the gas sales pipeline. Sometimes this gas is used as fuel, and them the remainder is flared or vented. In many instances, it is economically attractive to compress this gas to a high enough pressure so it can be sold. Compression may also be required for environmental reasons. Flash gas that might otherwise be flared may be compressed for sales or gas produced with oil (associated gas) may be compressed for re-injection to avoid, flaring or to help maintain reservoir pressure. In some marginal gas fields, and in many larger gas fields that experience a decline in flowing pressure with time, it may be economical to allow the wells to flow at surface pressures below that required for gas sales. In such cases, a booster compressor (one where the ratio of discharge to suction pressure is low) may be installed. Booster compressors are also used on long pipelines to restore pressure drop lost to friction. The use of large compressors is probably more prevalent in oil field facilities than in gas field facilities. Oil wells often require low flowing surface pressures and the gas that flashes off the oil in the separator must be compressed. Often, natural gas is, injected into the tubing of the well to lighten the column of liquid and reduce downhole pressure. This "gas lift" gas is produced back with good fluids at low pressure. Compressors are used so the lift gas can be recirculated and

INTRODUCTION : 1.1 Why water treatment? Pure water [H2O] is a colourless, odourless and tasteless liquid. It plays a huge part in everyday life: 70% of the earth’s surface is covered by water in the form of oceans, and the rest of the planet has large quantities of water in the form of lakes, rivers and watercourses, ice and snow, and humidity, as well as the principal element of animal life (>50%) and plants (approx. 80%). When we talk about water in general, we usually mean water for some specific purpose, e.g. drinking water or process water for industry. This is where the term water treatment comes into the picture, as the available water resources or that provided by nature is not always of a suitable quality for immediate use for the specific purpose. Drinking water must be pure, and should preferably taste good too, and it must not contain substances that could cause problemswith daily use. Process water, which is water that forms a direct and important part of a process or product in industry, must have a chemical composition and temperature that is precisely suited to the specific requirements.