Our Graham Desuperheaters are used to lower the temperature of superheated steam and can maintain a set outlet temperature when flow rate or pressure varies.
Graham fabricates custom Venturi or Steam-Atomizing Desuperheaters for industries that include power, refining, pulp and paper, food and beverage, plastics and pharmaceuticals.
Our Graham Desuperheaters are "in-line" units with flanged, buttweld, or NPT connections, shipped fully assembled and ready for immediate installation. Manufactured under an ISO-9000 quality program, the desuperheaters can also be stamped for ASME pressure vessel standards or fabricated to ANSI piping standards.
Graham Venturi Desuperheaters, which use a venturi nozzle to atomize the cooling water, are available in two styles: Double-Venturi (SV-1) and Single-Venturi (SV-2). The SV-1 is our most common style, with a venturi spray nozzle inside a venturi pipe. This style is capable of moderate turndown up to 10:1, low outlet superheat, and moderate pressure drop. The SV-2 is a scaled-down version of the SV-1, with only a venturi nozzle installed in a standard pipe. Turndown capability is much lower at 3:1 and outlet superheat is higher, but this style induces no pressure drop.
The Steam-Atomizing (SA) Desuperheaters use high pressure steam to atomize the cooling water. Turndown can be very high, up to 50:1, outlet superheat is low, and pressure drop is negligible.
Advantages of Graham Desuperheaters
Advantages of Graham Desuperheaters:
•Each Graham Desuperheater is custom-engineered and built for the specific application, ensuring trouble-free service for years.
•Range of maximum turndown ratios
•Minimal pressure drop
•Design code compliant
•Range of outlet superheat capabilities
•Variety of standard materials
•Horizontal or vertical orientation with upward flow
Applications for Graham Desuperheaters
Typical applications include:-
Boilers running at reduced loads, or with high cycling, produce variable temperature steam. Graham Desuperheaters can stabilize superheat over wide flow ranges.
Surface condensers work most efficiently when supplied with saturated steam. This eliminates the need to add tubes for cooling superheated steam, and prevents stresses caused by thermal expansion when hot, dry steam enters the condenser.
Turbine bypass systems require systems of pressure reducers and desuperheaters to reduce the pressure and temperature normally handled by the turbine.
Graham Desuperheaters can help control a variety of processes. If steam temperature is not constant, a process may become uncontrollable, especially when steam flow or pressure fluctuates. This can impact product quality, force unscheduled downtime, create personnel safety issues, and cost a great deal in repairs and replacements.
Thinner pipe and lighter flanges
Cooler steam can require thinner pipe schedules or smaller flange classes than superheated steam. Aside from lower costs, this can reduce lead times for piping, valves, controls, and other equipment during initial construction or shutdown maintenance.
Preventing lubricant degradation
Superheated steam may quickly degrade certain lubricants, so saturated steam is preferred for expensive specialty items such as pumps and compressors.
Protecting downstream equipment
Some metals are not suitable for high temperature service, but desuperheated steam often allows use of carbon steel and lower grade alloys instead of stainless steels and high-grade alloys, which are often necessary at high temperatures.
Properly designed desuperheaters ensure complete atomization of water droplets, and thorough evaporation and mixing downstream. This prevents damage to elbows, valve seats, heat exchanger tubes, other downstream equipment, and even some products
Desuperheaters are usually designed for steam cooling, but the same principles apply to any vapor. Graham has decades of experience designing and fabricating gas desuperheaters. Recent applications include methanol, toluene, natural gas, R-134a, and air. We can also design for any mixture of gases required.