Masoneilan DSH Series Desuperheater

Overview

The Masoneilan DSH Series is a desuperheater from Baker Hughes Masoneilan, used to control steam temperature by spraying atomised water into a steam line. Steam leaving a boiler, a heat recovery steam generator or a turbine often arrives hotter than the downstream equipment or process can accept, and the Masoneilan DSH brings it back to a target temperature as the injected water evaporates into the steam. Baker Hughes positions the range mainly for boiler and HRSG applications and for process uses such as steam turbine extraction and exhaust to process in the power industry.

In Oman and the GCC, Seven Star LLC proudly supplies the Masoneilan DSH to power generation, refining, petrochemical and industrial steam users across the Sultanate of Oman and the wider GCC. Because desuperheaters are engineered to order, our instrumentation division in Muscat works with you on the pipe size, ratings, nozzle selection and materials, and each order is supported with genuine Baker Hughes documentation.

Desuperheating Operating Principle

In operation, steam enters the Masoneilan DSH and atomised water is sprayed into the flow. The water is delivered by a spring-loaded, variable-geometry spray nozzle with a hollow cone spray pattern, designed to produce a primary atomisation with an optimal droplet size for efficient mixing with the steam. As the droplets evaporate they absorb heat from the steam and the steam temperature falls. Baker Hughes states that, with an appropriate control feedback system and valve, the desuperheater can create a consistent thermal distribution at the desired steam temperature within three metres.

The desuperheater itself does not decide how much water to inject. The spray water is controlled by a separate water supply valve, driven by a control loop that monitors a downstream temperature probe, so the DSH is applied together with a control valve and feedback system. The design also allows proper condensate drainage and is intended to avoid flashing that could damage the flow profiler, liner or nozzles, and, used with the right control valve, to avoid sending excess water into the main steam pipeline.

Engineering Design of the Masoneilan DSH

The radial spray line of the Masoneilan DSH comes in two variants. The DSH-110 includes a flow profiler, a Masoneilan feature installed upstream of the spray nozzles that directs the steam toward the centre of the pipe, creates a turbulent mixing zone and then lets the flow expand just before the nozzles. This improves mixing, limits large temperature gradients at the pipe surface and reduces thermal stress on the nozzles. The DSH-120 uses an internal liner welded into the main line and suspended from the housing with a small clearance, which protects the housing against water impingement and thermal shock where the spray water is injected.

For boiler attemperator duty where a radial style is not preferred, the DSH-200 is an insertion-style design with a fully forged body contoured to manage the thermal stress of continuous temperature cycling and spray water quenching, in ANSI 1500 and 2500 bodies. All styles are available in carbon steel or a range of chrome-moly grades. The Masoneilan DSH is designed to ASME B31.1 and can be manufactured under the ASME Boiler and Pressure Vessel Code Section I with an S-Stamp for installations within the boiler or HRSG boundary limits. A back pressure plate option is covered by the model numbering system.

Key Features

The following features, drawn from the Baker Hughes fact sheet and technical specification, describe what the Masoneilan DSH offers for steam temperature control:

• Radial spray designs with a flow profiler (DSH-110) or a pipe liner (DSH-120), plus an insertion-style DSH-200 for high thermal cycling duty.
• Spring-loaded, variable-geometry hollow-cone spray nozzles with individual Cv values of 0.4, 0.8, 1.5, 3.0, 5.0 and 10.0.
• Nozzle quantities from 1 to 8 or more give a combined system Cv from 0.4 to 80 and above, to match the water demand of the application.
• The flow profiler limits large temperature gradients at the pipe surface and reduces thermal stress on the nozzles.
• The thermal liner protects the main pipe from water impingement and sharp temperature gradients and extends service life.
• Pipe sizes from 4 to 48 inch and ratings from ANSI 150 to 2500 are standard, with larger sizes and higher ratings on request.
• Water manifold connections from 1 to 6 inch are available in welded and flanged forms, built to ASME B31.1.
• Material options span carbon steel to chrome-moly grades with temperature limits up to 649 degrees Celsius.

Industrial Applications

Baker Hughes lists interstage attemperator, terminal attemperator and process steam desuperheater as the main applications of the Masoneilan DSH, in power generation, refining, petrochemical and pulp and paper plants. An interstage attemperator sits between superheater sections in a boiler to protect the downstream tubes and to trim final steam temperature, while a terminal attemperator conditions steam just before it leaves for the turbine or the process. In Oman, those functions are needed wherever boilers and heat recovery steam generators raise steam: power and desalination plants, refinery and petrochemical steam networks in Sohar and Duqm, and industrial utility systems in Salalah and Muscat.

In Oman and the GCC, Seven Star LLC supplies the Masoneilan DSH alongside other Masoneilan steam equipment. Projects that need pressure reduction and desuperheating combined in one body can review the Masoneilan 84000 SteamForm steam conditioning valve and its seal kit, and for the water supply control valve in a desuperheating loop engineers can consider a globe valve such as the Masoneilan 41005 cage-guided control valve, subject to the sizing of the application.

Technical Specifications

The table below summarises the published data for the Masoneilan DSH as given in the Baker Hughes technical specification (Rev. D) and fact sheet. Please consult the full documents for the numbering system, nozzle flow curves and materials list.

Related Masoneilan severe-service valves include the Masoneilan 49000 Series V-LOG valve and Masoneilan 72000 Series large mass flow valve.

Request a Quote for Masoneilan DSH

Seven Star LLC invites power plant engineers, EPC contractors and steam system maintenance teams across Oman and the GCC to submit a formal request for quotation for the Masoneilan DSH. Please send the steam pipe size and rating, steam flow, inlet and target temperature, spray water pressure and temperature, and the preferred design (flow profiler, liner or insertion), and our team will confirm the configuration, advise on regional availability and provide the Baker Hughes technical specification for download from this page. In Oman and the GCC, Seven Star LLC delivers genuine products with manufacturer documentation, warranty coverage and responsive local support.