Assignment # 1

Title:“Steam Utilization in Industry”

“TEXTILE ENGG UTILITIES & SERVICES”M.E- 3112

Submitted by: Muhammad Muddaser Sharif

07-NTU-087“B”

6th Semester

Submitted to: Sir M. HASSAN Sb

“Steam Utilization in Textile Industry”

Types of energy used in the textile industry:In general, energy in the textile industry is mostly used in the forms of: electricity,

as a common power source for machinery, cooling and temperature control systems, lighting, office equipment, etc.; oil as a fuel for boilers which generate steam; liquified petroleum gas; coal; and city gas. Table 1 compares the energy consumption shares of various specialized technical fields and it can be seen that energy consumption is relatively high in the fields of dyeing and finishing, fiber production, spinning, weaving and clothing manufacturing.

Steam:Like many other substances, water can exist in the form of either a solid, liquid,

or gas. We will focus largely on liquid and gas phases and the changes that occur during the transition between these two phases.

Steam is the vaporized state of water which contains heat energy intended for transfer into a variety of processes from air heating to vaporizing liquids in the refining process.Perhaps the first thing that we should do is define some of the basic terminology that will be used in this course.

Steam utilization:Steam has come a long way from its traditional associations with locomotives

and the Industrial Revolution. Steam today is an integral and essential part of modern technology. Without it, our food, textile, chemical, medical, power, heating and transport industries could not exist or perform as they do. Steam provides a means of transporting controllable amounts of energy from a central, automated boiler house,

where it can be efficiently and economically generated, to the point of use. Therefore as steam moves around a plant it can equally be considered to be the transport and provision of energy. For many reasons, steam is one of the most widely used commodities for conveying heat energy. Its use is popular throughout industry for a broad range of tasks from mechanical power production to space heating and process applications. Reasons for using steaminclude:

Steam is efficient and economic to generate Steam can easily and cost effectively be distributed to the point of use Steam is easy to control Energy is easily transferred to the process The modern steam plant is easy to manage Steam is flexible Ability to release heat at constant temperature High heat content Ease of control and distribution Fire and flame proof Temperature breakdown is very easy by pressure reducing valve Can be used for direct & indirect heating Clean, odorless and tasteless

Why do we use steam?Steam1 has come a long way from its traditional associations with locomotives

and the Industrial Revolution. Steam today is an integral and essential part of modern technology. Without it, our food, textile, chemical, medical, power, heating and transport industries could not exist or perform as they do. Steam provides a means of transporting controllable amounts of energy from a central, automated boiler hou economically generated, to the point of use. Therefore as steam moves around a plant it can equally be considered to be the transport and provision of energy.

For many reasons, steam is one of the most widely used commodities for conveying heat energy. Its use is popular throughout industry for a broad range of tasks from mechanical power production to space heating and process applications. Reasons for using steam include:

Steam can easily and cost effectively be distributed to the point of use Steam is easy to control Energy is easily transferred to the process Steam is efficient and economic to generate The modern steam plant is easy to manage Steam is flexible se, where it can be efficiently and.

Production of steam:The production of steam is done in the boiler.

BOILER: A boiler is a closed vessel in which water or other fluid is heated. The heated or vaporized fluid exits the boiler for use in various processes or heating applications.

Most manufacturing industries require steam for a variety of uses. Basic plant heating and air conditioning, prime movers such as turbine drives for blowers and compressors, drying, constant temperature reaction processes, large presses, soaking pits, water heating, cooking and cleaning are all examples of how steam is used. Steam produced by industrial boilers can also be used to generate electricity in a cogeneration mode which uses a conventional steam turbine for electric power generation and low pressure extraction steam for the process. The electricity is then used by the plant or sold to a local electric utility company. As an alternate cogenerating system, a gas turbine can be used for power generation with a heat recovery steam generator for steam. Thousands of boilers are installed in industrial and municipal plants, providing lower pressure and temperature steam than utility boilers dedicated to large, central station electric power generation. In an industrial plant, the dependability of steam generating equipment is critical. Most often, the industrial operation has a single steam plant with one or more boilers. If the steam flow is interrupted, production can be seriously impacted. Accordingly, industrial boilers must be very reliable because plant productivity relies so heavily on their availability. Loss of a boiler for a short time can stop production for days if, for example, materials cool and solidify in process lines. For this reason, some industries prefer multiple smaller units. Proper equipment selection can be accomplished only in the framework of a sound technical and cost evaluation. This requires a working knowledge and understanding of the performance of the different steam generating unit components under various conditions, including the significance of the many different arrangements of heat absorbing surfaces, the characteristics of available fuels, combustion methods and ash handling. The owner must also establish the present and future steam conditions and requirements. All pertinent environmental regulations must also be considered. A brief summary of boiler specifications is below:

Boiler Specification Factors

Steam pressure Steam temperature and control range Steam flow Peak Minimum Load patterns Feedwater temperature and quality Standby capacity and number of units Fuels and their properties Ash properties Firing method preferences Environmental emission limitations sulfur dioxide (SO2), nitrogen oxides (NOx),

particulate, other compounds Site space and access limitations Auxiliaries Operator requirements Evaluation basis

Types of boiler

• Fire tube boiler ( hot gases passes through tubes) Economical capacity & pressure is lower than 25 tph and 17.5

kg/cm2 respectively. Ability to meet wide and sudden load fluctuations Low installation & maintenance costs

• Water tube boiler ( water passes through tubes) Range is available from 4 to 230 tph Very suitable for heavy and steady loads Normally used for high pressure steam requirement. High installation and maintenance costs

Improvement in efficient use of steam

(1) PipingThe noted feature of steam use in the textile industry is that the amount of steam

involved is not so large but the locations where steam is required are widespread so that steam losses due to heat radiation from steam transportation pipes and pressure drops are considerable. Therefore, for steam transportation over long distances, high pressure and smalldiameter rather than low pressure and large-diameter piping is desired, with pressure reducing valves placed as necessary to regulate the steam pressure at the point of use, thereby curbing heat losses. Also, as pressure losses around bends are great, it is desirable to make their radii large. In order to prevent steam leaks from joints due to the thermal expansion of the pipe, expansion joints should be placed where required. Furthermore, in order to maintain the temperature inside the valve, tank and treatment tank as well as the piping, it is necessary to install

them heat-insulated, using appropriate heat insulating materials, so as to efficiently use steam while preventing heat losses.

(2) Steam accumulators:Since live steam is often used in dyeing factories, fluctuations in steam use

during working hours are large. On the other hand, since high performance water tube boilers and once-through boilers are designed such that water retained inside the boiler is very little, the boiler cannot react to momentary and sudden load changes, while responding to automatically controlled slow load changes isnot a problem. In such a case, a steam accumulator can be installed midway through the heat transporting pipe, between the boiler and the heat consuming load, in order to store excess steam when the load is light by transforming it to heated water. This then transforms the heated water back to steam when the load is heavy in order to reinforce supply to the load. This allows the boiler to continuously operate with the average load and is quite advantageous in view of energy saving.

Recycling of drain:

So far, after its heat energy is consumed, steam has been drained off. However, in view of energy saving, it is necessary to collect and recycle the heat energy carried by the drain water.

Use of Steam in Textile Chemical Processing:

Dyeing requires steam to heat the liquor to the required temperature and maintain the temperature for a specific period of time. In such process the latent heat of steam is used, hence the vapor is condensed as it gives up its heat content. In order to have continuous steam heat, one must continuously remove the condensate formed. Steam trap is a device used in the steam distribution line to drain the condensate alone without letting the steam to leak. These traps act as a valve. Three different types of traps are available namely, thermo dynamic, float & bucket type. Each one of them is used depending on the field of application.

The failure of these traps will result in steam leakages and such losses increase the operating cost of the process, increase the process time and this means more use of energy and costs. The failure of the trap can be categorized as leaking, blowing, rapid cycling & clogging. From the various literatures and the energy conservation manuals it has been observed that about 15 to 30% of traps in the steam systems would fail if they are not maintained. Further 50% of the traps may fail in the plant with no active steam trap testing and repair program. With regular maintenance plan this figure can be reduced to lesser than 3%.