It consisted of an array of vertical cast iron tubes connected to a tank of water above and below, between which the boilers exhaust gases passed. Hvac economizers 101 principles and operations for efficiency. Performance optimization of dual pressure heat recovery. Using this module, engineers can design a wide variety of economisers for fired boilers, waste heat boilers, hrsgs and for other hot gas sources of chemical plants. This is why in the recently published ashrae humidity design guide it is recommended that economizer operation. Boilers that exceed 100 boiler horsepower, operating at pressures exceeding 75 psig or above, and that are significantly loaded all year long are excellent candidates for an economizer retrofit. Vogt power international specializes in the manufacture and delivery of heat recovery steam generators hrsgs meeting todays stringent environmental standards while maintaining operational and performance excellence.
The hrsg consists of the same heat transfer surfaces as other boilers, except for the furnace. Heat recovery steam generators hrsgs are important components for. Economizer is a tool designed to work both on board and in offices, which allows control of the main factors influencing the consumption of our fleet. The mass flow rate of the working fluid in the economizer, evaporator and. Jun 20, 2017 major deficiencies in current hrsg design. However, since hrsgs in general are of the convective type, one can easily simulate their off design performance without actually designing the hrsg in terms of tube sizes, dimensions, surface areas, etc. The heat is converted into usable steam by the heat transfer surfaces within the hrsg. Software designed to model and simulate hrsg operations can provide. Most buildings today use either enthalpy or temperature to determine if outside air can be used for free cooling. Model of a heat recovery steam generator hrsg process and.
Heat recovery steam generators the heat recovery steam generator hrsg provides the thermodynamic link between the gas turbines and steam turbines in a combinedcycle power plant. Boiler economiser sometimes called economizer is the energy improving device that helps to reduce the cost of operation by saving the fuel. Bare tubes are typically utilized in order to minimize ash fouling, but some boiler oems design their economizers with finned tubes, either spiral or long finned. Poor condition of drain line serving an lp economizer was found during an inspection of the lower crawl space below this hrsg fig 33a. There is only one design mode analysis but there can be numerous off design cases. Economizer systems may be used even if not required, provided that the economizer system conforms to the requirements in sections 6. Gas flow distribution or heat transfer into the economizer section is improved through use of guide vanes at inlet of economizer duct. Xace is an incremental program that rates, simulates, and designs crossflow heat exchangers, such as air coolers and heat recovery bundles. Vogt power internationaldesigns for all your hrsg needs. Also, the shockmaster economizer design allows complete venting prior to startup. The cre rectangular economizer can be utilized up to 2,200 hp for capturing the waste heat and preheating boiler feedwater, makeup water heating, hot water boilers, and potable and process water applications.
The level of detail and type of analysis will drive. To optimise economiser design for better performance. Pdf application and design of an economizer for waste. These examples are available in the hrsgs software. Adjust the heating surfaces so that the final super heater steam and final reheater steam have the desired temperature and pressure. Design and modification of heat recovery steam generators for cycling operations akber pasha and robert allen vogtnem inc.
This increases the overall boiler thermal efficiency, resulting in more steam with less fuel. Identify economizer sensors, controllers, and controlled devices on a miniature or packaged hvac unit. Using thermohydraulic simulations to assess hrsg performance. The heating surface elements are bare and finned tubes integrated with collector headers and interconnecting piping systems. Riser piping for the evaporator section was increased to 12 inches from the original 8 or 10 inches to improve circulation. Now in our fifth decade in waste heat recovery economizer engineering, etech has encountered and successfully addressed every imaginable economizer and boiler configuration and application of the waste heat recovery products we design, fabricate and install. The economizer in boiler tends to make the system more energy efficient. Economizer design software features firecad economiser design software is a windows based user friendly design software. The hrsg consists of a superheater evaporator and economizer generating steam at 600 psig. Modeling, simulation, and control of steam generation processes. Heat recovery steam generators hrsg and stack economizers can be used with industrial processes such as ovens, dryers, oxidizers and large capacity boilers. Heat recovery steam generators primer an introductory. This paper provides the main characteristics of a modeling and simulation tool to analyze the steady state and transient operation of a hrsg heat recovery steam generator when they are subject to load changes.
The heat recovery steam generator hrsg is composed of numerous mechanical heating surface components superheaters, evaporators and economizers and steam drums. The results were obtained with hrsts performance modeling software, performance pro tm. All the solutions lead to the zero pinch point and infinite heat transfer surface. Each hrsg solution is customengineered to meet your desired operating flexibility and performance requirements. Main economiser design methodologies available in literature are described and their advantages and disadvantages.
Options for improving the efficiency of heat recovery steam. In this design, the high pressure stage is followed by the low pressure system. Vogt offers a large and robust hrsg aftermarket parts and service capability, with full turnkey options from design through. The economizer also prevents flooding of the boiler with liquid water that is too cold to be boiled given the flow rates and design of the boiler. Clearly, the last sections of the highpressure economizer 1.
Model of a heat recovery steam generator hrsg process. Ensure that system changes are evaluated and modifications are included in the design e. Design methodology of heat recovery steam generator in. This leads to excellent lowload performance, and is a good option for cycling hrsgs. Hrsg, the economizer will be located directly downstream with respect to gas flow of the evaporator section. The superheater is a separate serpentine tube heat exchanger which. Hrsg generating more lowpressure steam than high pressure steam, then a larger pinch and approach may be used. The function of the combined cycle heat recovery steam generator hrsg system is to provide a method to extract sensible heat from the combustion turbine ct exhaust gas stream.
Boiler economiser sometimes called economizer is the energy improving device that helps to reduce the cost of operation by saving the fuel the economizer in boiler tends to make the system more energy efficient in boilers, economizers are generally heat exchangers which are designed to exchange heat with the fluid, generally water. The first combined cycle power plant with a benson heatrecovery steam generator hrsg the 390 mw cottam development center, located in great britain was successfully commissioned in 1999. The shockmaster economizer design allows uniform upward water flow through the tubes, causing uniform temperatures across each tube panel, minimizing pressure part stress. Mcgill, in heat recovery steam generator technology, 2017. The main advantage of the proposed method is that it permits a better understanding of influence of the design parameters on. Experiment with a working economizer unit under normal operations and abnormal or failed conditions to help students to determine a solution to the economizer problem for optimum efficiency of. Although it does not produce the highest combinedcycle thermal efficiency, it is a sound economic ge combinedcycle product line and performance ge power. However, since hrsgs in general are of the convective type, one can easily simulate their offdesign performance without actually designing the hrsg in terms of tube sizes, dimensions, surface areas, etc. Economizers are used to recover the useful heat in exhaust or flue gas before it is released into the atmosphere and transfer it to the steam production cycle. The following study assessed the impact on overall plant efficiency of lowering the lp economizer approach temperature in a triplepressure hrsg. But it also identifies the nine exceptions listed below. Application and design of an economizer for waste heat recovery in a cogeneration plant article pdf available in thermal science 201500.
Design of dual pressure heat recovery steam generator for. Design pressures for an hrsg behind an advanced gt are around 21 mpa 3,000 psig. The economizer was reconfigured to reduce the waterside pressure loss, and heattransfer surface was increased by 16% addition of two rows to reduce the exhaustgas temperature figure 6. Design methodology of heat recovery steam generator in electric. Chanute can produce economizer elements with either bare, spiral finned, or long finned tubes, and if you prefer, re design your unit to one of the other tubetypes. Check all other design criteria from some hrsg oem design handbook. A software is required to perform this complex analysis, particularly if the hrsg has multiple pressure levels and has a complex arrangement of heating surfaces. Unlike in a conventional steam generator, where the steam demand drives the design case, in a hrsg. Heat recovery steam generator design turbomachinery blog.
Obtain an installed cost quotation for and determine the costeffectiveness of a condensing economizer. In the off design mode the pinch and approach points fall in place. Rate, simulate, and design air coolers and economizers. The performance model was set up for an ideal case where an hrsg with proper gas baffling was compared to the same hrsg with a twoinch gas bypass between the panel and casing wall, and a fourinch gap between the coils throughout the hrsg. An economizer saves boiler energy consumption an average boiler operates with an efficiency of approximately 66%, which means that 34% of the energy can be considered waste heat. The last step is the performance calculation of the cycle. An economizer, also called regenerators, is a type of heat exchanger that recovers heat from flue gasses to preheat fluids or puts it to use in another part of the. Design and modification of hrsgs for cycling operations pg. Heat recovery steam generator wiki odesie by tech transfer.
Hence, predicting hrsg performance under different conditions is a must for consultants, plant engineers and hrsg designers. By using the air preheater and economizer boiler efficiency can be increased. Abstract todays heat recovery steam generators, which form a part of combined cycle plant, are exposed to more severe operation than just running at a base load. Economizer allows the planning of travel costs, dock entry for maintenance and comparison of different ships to see which ones are most suitable. A feedwater economizer is appropriate when insufficient heat transfer surface exists within the boiler to remove combustion heat. In any heat transfer equipment such as a boiler or heat recovery steam. Comparison of power enhancement options for retrofit to. The first step in doing a simulation of hrsg operation is to build a software model using the mechanical design data for the unit in question. For our economizer, we will use the iframe design, but use two tubes per bundle with 6 pipe headers, so we will once again need bent tubes, using a 6 bend radius.
Ger3574g ge combinedcycle product line and performance. How to boost hrsg performance and increase your plants. Options for improving the efficiency of heat recovery. The heat transfer and pressure drop correlations are continually improved as a result of our ongoing research. In boilers, economizers are generally heat exchangers which are designed to exchange heat with the fluid, generally water. To this day, more than 100 benson heat recovery steam generators have either been commissioned or are currently being built. A common application of economizers in steam power plants is to capture the waste heat from boiler stack gases flue gas and transfer it to the boiler feedwater.
Boilers and diverter dampers examples of recent analysis, modelling, upgrades and proven construction solutions. Hrsgs for next generation combined cycle plants power. Thermal design and optimization of heat recovery steam. Quality materials and superior construction is essential to producing heat recovery systems that are, by design, engineered to be the most reliable steam generators in the world.
In multipressure unit, the various economizer sections may be split, and be located in several locations both u pstream and downstream of the evaporators. The evaluations were performed using the hrsgs software. It was patented by edward green in 1845, and since then has been known as greens economizer. Modulardesigned units are completely shopassembled to maximize transportation efficiencies and minimize field costs by lowering man hours needed for installation.
Case studies huntsman hrsg rentech boiler services. The figure shows a hrsg generating 39,500 lbh of highpressure steam at 800 psig750 f and 6270 lbh low pressure steam at 100 psig. The heat recovery steam generators shall consist of the following scope of supply. Economizer applications etech heat recovery systems. How to recover and revamp boilers to adequate mechanical and operations behaviour. Based on actual and existing hrsg in most combined cycle power plants, a water tube hrsg including two superheaters, one evaporator and one economizer is considered in the optimization.
To optimise economiser design for better performance a. Design of the hrsg the design of hrsg depend on thermodynamic parameters of exhaust gases from gas turbine in simple cycle mode such as temperature,pressure and mass flow rate of gases to evaluate the operations parameters and geometric design of hrsg. The first successful economizer design was used to increase the steamraising efficiency of the boilers of stationary steam engines. They are typically configured to handle either horizontal or vertical gas flow, they can be designed to precisely meet to your performance, pressuredrop, and space constraints. The cre rectangular economizer can be utilized up to 2,200 hp for capturing the waste heat and preheating boiler feedwater, makeup water heating, hot water. Hrst engineers recommended removing the stainlesssteel bellows expansion joint around this drain, which had lost about 25% of its wall thickness in five years of service fig 33b. Hrsg simulation is a method of predicting the design or offdesign performance of. The chart to the right summarizes the parameters that are used to measure the temperature and moisture characteristics of air. For the design case,a pinch and approach point of 15 f was used when the gas turbine operates at 100 % load at the design ambient temperature. To help reduce the thickness of the hp drum, a higher grade of drum materialsa299 gr. Economiser design software for coal, wood, biomass, gas, oil fired boilers. If recirc flow is taken from the economizer outlet, reducing the temperature set point from 140f to f increases steamturbine output by 160 kw.
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