NEM is a global leader in the field of gas turbine exhaust systems requiring clever flue gas routing, modulation and tight shut-off solutions. With our customized Exhaust & Diverter Solutions portfolio, NEM complements and supports the transition towards a decarbonized and sustainable energy environment. Our portfolio covers both new installations and custom tailored retrofit solutions for conversion projects, for conversion projects, downstream any type of gas turbine OEM.
Our core competences are engineering, including basic and detail design of individual tailored solutions, structural engineering supported by state-of-the-art methods like 3D-modelling, lifetime analysis, CFD- and FE-analysis and project execution, and manufacturing. Short delivery times and challenging cost targets are met by a high degree of standardization and through cooperation with experienced, long-term fabrication partners around the globe. On-time deliverables, workmanship and quality are ensured by our own internal fabrication supervision, stringent quality assurance procedures, functional shop tests at every phase of the process up to packing inspections, and logistic services. All of our processes – from proposal stage to delivery and beyond – are executed based on current ISO:9001, ISO14001 and OHSAS:18001 standards.
Exhaust gas bypass systems contribute operational flexibility, efficiency and safety to a combined cycle power island. The heart of any bypass system is the diverter damper. NEM diverter dampers combine state-of-the-art design principles and technology with more than seventy years of experience and empirical field data.
The result is that NEM diverters have earned a reputation as the safest and most reliable dampers in the industry. While based on a high degree of standardization, diverters can also be custom-engineered to meet the specific combustion turbine’s characteristics, as well as the project’s individual requirements.
The stacks in particular are always designed to project specifications, such as height, design codes, acoustic requirements, environmental loads and applicable aviation warning regulations.
Advantages of the NEM-designed Bypass systems with diverters are:
Simple cycle power plants consist of a combustion turbine and an integrated chimney or exhaust stack.
Many power island projects start with a simple cycle design in order to minimize initial capital costs, reduce equipment installation time and enable power generation as quickly as possible. Traditional simple cycle exhaust systems are typically designed with a self-supported exhaust chimney or stack. This design is used when no future conversion to combined cycle operation is envisaged, but it is not cost and time effective for future extension to combined cycle configurations. In such a case, stacks with an external support steel structure and elbow ducting present an easy to convert solution.
The NEM design portfolio covers both versions: the base mounted as well as the elbow duct design.
Advantages of the NEM-designed simple cycle systems are:
Guillotine-type blanking plates are extensively used in exhaust gas bypass systems as a secondary shut-off device in conjunction with the diverter damper in order to create a “man safe” environment within the downstream HRSG when the combustion turbine is operating.
As stand-alone solution, the guillotine damper type will typically utilize a temperature-proof design with rack and pinion drive system and a gas-tight, fully enclosed bonnet.
Almost the full cross-section of the duct is available once the guillotine blade is fully retracted, resulting in a very low pressure drop. Depending on the application, designs with or without seal air are possible.
Advantages of the NEM-designed guillotine dampers and blanking plates are:
The primary function of an HRSG stack damper is to slow down the cooling rate of the HRSG between gas turbine starts. By minimizing the dwell time necessary for HRSG restart, thermal stresses for pressure parts of the HRSG are reduced, resulting in an increased life time.
Stack dampers also prevent rain from entering the HRSG during sustained shutdowns. The most advanced stack damper design incorporates aerodynamic aspects and an improved drive system, which provides independent overpressure relief on the blades in case of process upsets.
NEM stack dampers for HRSGs come in standardized, parametric 2-blade- or individual 4-blade designs. The dampers can also be retrofitted to existing HRSG stacks relatively quick and easy, utilizing either the complete damper configuration with frame or the Stack Damper Retrofit Kit.
Advantages of the NEM-designed stack dampers are:
Louver dampers by NEM are robust flow control and/or shut-off devices used in flue gas ducts, specifically designed for the demanding environment inherent in combustion turbine exhaust installations.
NEM designs and builds louver dampers in accordance with the plant-specific parameters and clients’ individual specifications, and the dampers are available in various designs, dimensions and shapes, with or without duct section (T-Box). Actuation can be manual, electrical, pneumatic or hydraulic type. The construction materials used depend on the operating temperature and pressure, abrasive or corrosive environment and other process operating conditions. Louver dampers can be built as single or double louver versions, and are designed with either internal or external insulation.
Depending on the operating conditions and the required degree of tightness, different seal arrangements are available. Double louver dampers or twin-blade louver dampers with seal air injected in-between both blade planes provide a hundred percent tight barrier against gas leakage.
Advantages of the NEM-designed louver systems are:
Mega Project Egypt
Egypt
Guido Goepel
Business Unit Director Exhaust & Diverter Solutions
Looking for more information about our Exhaust & Diverter Solutions or curious how we can support your installation? Feel free to reach out – we’re happy to discuss your needs and provide the right support.
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