While each components affects operation, a note on orientation is warranted. Orientation can affect the speed of vaporization. Horizontal installations are most common, but vertical flow-up installations perform slightly better because of the positive effect of gravity. Vertical flow-down pipes perform less efficiently because of the negative effect of gravity, which reduces residence time.
Details of the actual control of a desuperheater are beyond the scope of this article; however, suffice it to say that pressure, temperature and flow sensors feed data to a control system that adjusts the spray-water control valve to deal with changing conditions.
Control Valve Considerations
When a desuperheating system is purchased, often each component will be specified and purchased separately. In other words, the desuperheater will be purchased from one vendor, the control valve from another and so on. Unless the process plant has an extensive expertise in the design of superheating systems — not often the case — this approach is problematic due to the complexity of these systems.
The reasons are:
There is generally a turndown specification for the system that needs to be met. The control valve has a turndown ratio, the desuperheater has a turndown ratio and the combination of the two has a completely different turndown ratio. Therefore, sizing and selection are critical to ensuring system performance is met.
Different desuperheater designs will have different differential pressure (dP) requirements across the nozzles. The control valve differential pressure must be coordinated with the differential pressure across the desuperheater nozzles to ensure system performance is met.
If there is a high differential pressure across the control valve — when a high pressure source is used to spray water into a low pressure steam line, for instance — cavitation can occur in the valve. The proper anti-cavitation trim must be installed in the control valve to suppress cavitation. If not, it is possible to have a cavitating pressure drop across the desuperheater nozzle, with catastrophic damage resulting, and potentially sending eroded desuperheater components into downstream equipment.
A desuperheater nozzle has a specific flow coefficient (Cv). A control valve also has a range of flow coefficients based on its design. The flow coefficient for the valve and desuperheater must be matched so that overall system flow coefficient is optimized.
It presents results in the thermal energy recovery system (TERS) investigation, and the possibility of introducing them to production vehicles as subsystems. This prospective new technology should reduce dependence on fossil fuels. One of the TERS systems' research objectives is to create a sustainable, electrical power source, suitable for the energy to be stored and later used in the electrical vehicle driving mode (EV)1. It will also lower the impact on the environment by reducing fuel consumption through the application of automotive thermoelectric generators (ATEG) instead of classical alternators that convert mechanical energy to electrical.
Pressure reducer and desuperheater system (PRDS) is used for Steam Conditioning Services for reduction of pressure and temperature of steam. Suitably designed pressure reducing valve installed on superheated steam line, reduces steam pressure to desired operating pressure. The steam temperature is reduced close to saturation by injecting water into high velocity steam by controlled water flow through water control valve and often injected into the steam where steam velocity and turbulence are at their highest, which gives quick and efficient cooling. The purpose of this project is to optimize the Pressure reducing and desuperheating system to overcome the current losses such as valve leakage, gland leakage and header leakage.