Figure shows the schematic diagram of plant with dimensions where the yarn drying is carried out. It consists of boiler with economizer placed vertically, steam carrying pipes, control valves, feed water arrangement, process equipments. Feed water is first heated in the economizer, and then it is further heated by the hot flue gases formed in the combustion chamber. This heated water then converted into the dry saturated steam by taking latent heat of vaporization from hot gases.
Steam is then carried to the 1st floor where the process equipments are placed. Steam is carried by pipes are insulated by glass wool so that the heat transfer loss is minimum during flow through pipes. Steam is then used for process heating in process equipment drums in which the dyeing process is carried out. In these drums thread bundle is placed in such a way that the dyeing to thread is uniform throughout the bundle. In drums proper pressure is built up in process equipment and then dyeing to threads is carried out.
2.2 Operation of plant
During last summer vacation, we had visited the swami textile for our IDP project. Swami textile is a dyeing factory, where the threads are dyeing in bulk. Main components those used for dyeing threads are boiler, process equipment, pipes, and colour mixture for mixing the different colours. Generally, steam, in industries, is either used for power generation or as a process steam. Here steam is used as a process steam. Steam generated by the boiler is used as a process steam for dyeing purpose. Heat carried by steam is used for giving heat to the threads bundle to impregnate the colour into threads properly. Product quality depends upon quality of steam. So steam is the main parameter for satisfactory operation. Steam quality depends upon various factors like feed water, fuel used for combustion, type of boiler used, steam carrying pipes, distance between generation of steam location and area of application.
During dyeing operation, water is fed to the boiler from water tank through economizer where temperature of water is increased to 800c. From where water is pumped by centrifugal pump running by 1hp motor. Boiler is fired tube boiler in which water is converted in to steam of temperature around 140 to 1600c and pressure of 2 to 3 kg/cm2. Steam is generated in wood fired water tube boiler by combustion of wood in the furnace. Steam generated in boiler tubes are carried to the process equipments through pipes, where steam is utilized for heating the threads. First threads are coloured by sprays and then steam is used to heat those threads for drying purpose. Steam used for this purpose should be such that it would be dry enough to make thread dry and at temperature of 1300c and pressure of 3 kg/cm2, but it should wet also so that threads are no burned out. So, steam of uniform quantity is necessary. Wood burnt in furnace will give heat to water and produces steam. Flue gases produced by burning of fuel will disposed to atmosphere through chimney. Steam supplied to the processing vessel is condensed and lead to the water tank and same water is fed to the boiler as feed water.
The working condition of actual existing boiler is shown in photograph. Boiler is shown and required mountings like pressure gauge, temperature gauge, water level indicator is mounted. Economizer is shown where heat is transferred from hot flue gases to inlet feed water. Water is preheated around 80 0c then water is heated to final temperature in boiler around 150 0c.