Science behind steam traps:
Energy in the form of mechanical and heat, exchange it selves between the process units in the chemical and power plants. Steam is the form of energy carrier. To do work in the process it travels in the pipelines, controlled and transfers it energy to the machines. Directly steam is costly. It governs the profit and efficiency of the industry. However, the difficulty rises while handling the steam during transport.
We know how heat is lost from a system of high object to lower object. Similarly, energy in the steam is lost at a rate to environment. To solve this problem, pipes and equipments perfectly insulated with glass wool type insulation. During the transport of steam, another problem comes into picture, i.e. steam condensate. Even when the insulation provided on the outer surface of pipes and equipments, some energy is lost to surrounding causing phase change of steam. Water phase formed in the pipelines. Steam trap insulation must be take care during the installation itself because if it fails most of the steam is lost.
Water when carried over along with steam it causes machinery failure and some cases disaster. It even decreases the efficiency of equipment leading to frequent break down. To solve this problem a device called steam trap designed. It has a mechanism that removes the condensate water from steam pipeline.
The main purpose of steam trap is
- To collect the water carried over by steam and drain it frequent.
- To control the loss of steam and to maintain the steam without condensate
- Venturi steam trap
- Orifice steam trap
- Bimetallic steam trap
- Float and thermostatic
- Inverted bucket
Steam trap selection depends on factor of steam temperature, pressure and volume flow rate, connecting ports. Steam used in industries classified as low-pressure, medium-pressure or saturated and high-pressure or supersaturated. Steam traps with same mechanisms cannot handle the above types its sizing depends on the pipe diameter and volumetric flow rate of steam.
Engineering application of steam trap:
Mechanism of steam trap operations is an automatic mechanical valve engineering design.
Steam traps location:
Steam trap fitted between along the pipelines and at entry points of equipments. Pressure drop across it gives an idea on the steam trap performance. To check steam traps condition the pressure gauges reading at inlet and outlet points should have less difference.
Estimation of steam loss through trap, calculation method
A steam chart is used for calculation of the temperature and pressure relation during the design of the equipments like heat exchangers and boilers. Steam loss calculator works based on the program that is written using steam chart algorithm. Steam losses mainly caused at the joints, gaskets and in most cases steam valves will leak at the stem seal. This energy cost estimated when the steam is lost through orifice of steam trap. To calculate overall loss Masoneilan formula is preferred.
Steam pipe heat loss calculated similarly to the calculation of steam mass and energy balance take around the boiler. To calculate steam flow all through the pipes a rotameter can be used. It gives the reading of physical parameter for energy loss calculator program.
Technology updates in steam traps application:
Steam loss caused from steam trap will affect the running cost of the plant and stem generation system. It is simple loss of money into air due to the heat transfer into surrounding atmosphere. Steam flow through pipe controlled and maintained by the steam control valves and the steam trap that separates the condensate formed in the pipe. Real time monitoring in steam distribution system (SDS) brought up the technology to control remote by wireless and LCD display.