Typical Steam Circuit
The steam distribution system comprises the piping and accessories between the boiler and process equipment utilizing steam (See typical steam circuit of a process plant using steam as heating medium for the process). The role of the distribution system is to transport steam from the boiler and deliver it to the process.
Usually, utmost care is taken by plants to procure capex components like the boiler. This may involve inviting techno-commercial offers from reputed vendors, and rigorous evaluation thereof before orders are placed on selected vendor. This procedure however is seldom followed for the steam distribution system. In case of the distribution network, a piping contractor is appointed under a rate contract and given the task of laying down the lines. Issues arise when such vendors rely on thumb rules or previous experience to install the pipelines.
The key objective of the distribution network is to transport steam as efficiently as possible, in the desired quantity and at the desired quality to the process. But some of the common issues we find across plants include :
- Pressure drop and steam starvation due to undersizing of steam lines
- Oversized steam pipelines leading to higher fixed distribution losses, higher opex and capex
- Frequent leakages in the distribution network due to condensate accumulation
- Drain traps not installed at desired locations and/or installed in a wrong way leading to Water hammer in the system, a major cause of frequent leaks and damaged pipes and pipeline accessories
- Necessary slope on Steam Piping not provided leading to condensate accumulation and water hammer
- Air Vents not installed at desired locations leading to increased process batch timing
- Displacement of the pipelines as pipe expansion is not adequately handled due to incorrect engineering
- Sagging of the pipelines due to inadequate supports leading to condensate accumulation
- Distribution losses of 7-10% against the ideal 3% distribution losses
Each one of these issues means that steam is not available at the right quality or quantity to your process. It also means that your KPIs of Energy Conservation, Safety, Reliability, Zero Downtime are all adversely affected.
Furthermore poor distribution design also leads to product (steam pipeline accessories) performance issues not attributable to the products themselves. Actually, product performance issues may arise out of faulty Steam Distribution System. Thus, the need for the focus on Steam Distribution System is utmost essential.