In 1991 the "User Group" methodology was introduced for the textile industries in The Netherlands. The Netherlands textile industry was able to achieve 8% energy consumption reduction nation wide. "User Group" is a methodology where companies with comparable processes collectively discuss problems and identify solutions. Comparable industrial processes are optimised by means of adjustments initiated by the exchange of experiences and gaining knowledge on new technologies.
Recently with the support of The Netherlands based NGO Solidaridad, CREM a consultation organization & TNO a Dutch research organization we, at conquest launched the User Group project here in Tirupur for the textile wet processing industries focusing on energy conservation & management in the steam generation and distribution systems. Ten Companies volunteered to participate in the project. After initial discussions and deliberations on energy saving opportunities the team decided to focus on steam generation & distribution areas. From the literature research and basic evaluation our team identified to focus on improving boiler efficiency, insulation & steam trap maintenance where opportunities exists for a low cost short-term effective benefits. This article is focused on steam traps as we found out during the initial stages of evaluation it has enough potential and contribution towards energy savings. The regular industrial practice is to adapt break down maintenance for failed traps once they have observed the change in heating cycle timings in the process of coloration and no active steam trap maintenance schedules are followed.
Thomas K Lago in PM Engineer magazine once wrote, "Lack of Steam Trap Knowledge Is the Weakest Link". Yes! It is true, when considering the steam distribution systems in the process; the steam trap is the least understood equipment. The foremost reason for this is the lack of fundamental knowledge about the trap. Before discussing further let us understand the working of the trap.
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%.
The functionality of traps is evaluated by various methods (visual, temperature and ultra sonic detection methods). The observations of traps by using ultrasonic equipments are limited due to their high costs. Yet there is a scope for evaluating the steam trap in a much easier manner. In this project, based on the less widely used Masoneilan & Napier formula (Obtained from the project report submitted to UNFCCC- AM0017/Version 02); the performances of the traps are evaluated. For the evaluation we suggested the industries to measure the input and output temperatures in the steam trap; the performance of the trap can be determined by evaluating the temperature differences. If the output temperature at the trap in the condensate line is more than 95C; it means steam is leaking through it, then the trap can be termed as faulty, depending on the condition of the trap, it can be further listed under any one of the before mentioned four faults namely blowing, leaking, rapid-cycling & clogging. From the observations and survey, the facts came into light that, about 25% of traps were found malfunctioning.