2015年8月31日星期一
Energy Use and Efficiency of Industrial Boilers
Energy Use and Efficiency of Industrial Boilers
Industrial Boilers typically operate to meet a desired heating load, which is to say that the output of the boiler can be easily adjusted to meet a load that is not constant. Industrial boilers operate to meet a process load that is driven by the production output for a product.
Industrial boiler applications are usually a multiple boiler configuration that include a lead boiler that meets the base load requirements supported by a lag boiler that that supports the load that is in excess of the lead boiler capacity. In some case there is also a standby boiler that is ready for operation in the case of a failure of the lead or lag boiler or to support the process when one of the other boilers is out of service for scheduled routine maintenance.
Note that during the course of the year, the designation of lead, lag and standby rotates through the boilers so that they have similar hours of operation over the course of year.
While industrial boilers can load follow, they cannot be frequently cycled on and off as thermal cycling can damage the units. To accommodate this requirement, the lag and standby boilers are typically in a warm standby mode where the boiler is maintained at a temperature that will allow it to be placed into service in a short period of time. Note that in a warm standby mode of operation, fuel is consumed and no usable output is produced.
Industrial boiler efficiency:
The efficiency of industrial boilers is the ratio of heat output to the fuel input. The heat output is in the form of steam or hot water. Both forms of these output streams can be measured to calculate the quantity of energy produced by the boiler. The input fuel in the form of oil or natural gas can also be accurately measured to calculate the quantity of energy input into the boiler. When calculating the input energy value for the fuel, one must note the assumption for the value of the heat of combustion of the fuel as it typically expressed in the form of higher heating value and lower heating value. Higher Heating Values for a fuel include the full energy content as defined by bringing all products of combustion to 77°F (25° C). Natural gas typically is delivered by the local gas company with values of 1,000 - 1,050 Btu per cubic foot on this HHV basis. Since the actual value may vary from month to month some gas companies convert to Therms. A Therm is precisely 100,000 BTU. These measures all represent higher heating values. Lower heating values neglect the energy in the water vapor formed by the combustion of hydrogen in the fuel. This water vapor typically represents about 10% of the energy content. Therefore the lower heating values for natural gas are typically 900 - 950 Btu per cubic foot.
Losses in boilers that affect the efficiency include heat loss through the walls of the boiler, heat loss through the exhaust and not combusting 100% of the fuel provided to the system. Steam boilers also have a blow-down requirement. Boiler feed water often contains some degree of impurities, such as suspended and dissolved solids that accumulate inside the boiler during normal operation. The increasing concentration of dissolved solids can lead to carryover of boiler water into the steam, causing damage to piping, steam traps and even process equipment. The increasing concentration of suspended solids can form sludge, which impairs boiler efficiency and heat transfer capability. To avoid boiler problems, water must be periodically discharged or “blown down” from the boiler to control the concentrations of suspended and total dissolved solids in the boiler. Surface water blow-down is often done continuously to reduce the level of dissolved solids, and bottom blow-down is performed periodically to remove sludge from the bottom of the boiler. The blow-down water has been heated inside the boiler and therefore uses some of the fuel but does not result in useful heat output. Note, there are devices that can be incorporated into a boiler to recover some of the blown-down energy but these are not standard equipment at this time.
Combustion and Gasification in Fluidized Beds Boiler
Fluidized Beds Boiler Features
1. Offers practical, comprehensive coverage of the design, analysis, and operation aspects of fluidized beds boiler2. Provides many worked out design problems, step-by-step design procedures, and real data on commercially operating systems3. Supplies valuable design data such as properties of coal, specific heat of gases, and design velocities4. Covers both bubbling and circulating fluidized bed boilers and gasifiers5. Contains four valuable appendices that eliminate the need to search for essential information |
| CFB boilers |
Coal fired Fluidized Beds Boiler technology
Besides being one of the best Clean Coal Technologies, fluidized beds are also proving to be the most practical option for biomass conversion. Although the technology is well established, the field lacks a comprehensive guide to the design and operating principles of fluidized bed boilers and gasifiers. With more than 30 years of research and industrial experience, ZG answers this pressing need with combustion and gasification in fluidized beds.This article is a versatile resource that explains how fluidized bed boiler equipment works and how to use the basic principles of thermodynamics and fluid mechanics in design while providing insight into planning new projects, troubleshooting existing equipment, and appreciating the capabilities and limitations of the process. From hydrodynamics to construction and maintenance, the author covers all of the essential information needed to understand, design, operate, and maintain a complete fluidized bed boiler system. It is a must for clean coal technology as well as for biomass power generation.Beginning with a general introduction to fossil or biofuel conversion choices, the article surveys hydrodynamics, fundamentals of gasification, combustion of solid fuels, pollution aspects including climate change mitigation, heat transfer in fluidized beds, the design and operation of bubbling and circulating fluidized bed boilers, and various supporting components such as distributor grates, feeding systems, and gas-solid separators.
2015年8月28日星期五
Fire tube Package Boilers cost
Fire tube Package Boilers cost
The ZG Fire tube Package Boilers is led by a dedicated team of highly experienced engineers with many years in the steam industry. The unit's business is based on internationally competitive technology, price and delivery and is dedicated to provide the full spectrum of steam services to their customers in South Africa and many export markets, as outlined in this divisional profile.
Fire tube package boiler design:
Firetube boiler designs include coal-fired boilers with chain grate stokers, wood fired boilers with fixed grates, oil/gas fired boilers, as well as custom-designed waste heat boilers. All Firetube boilers are designed and manufactured to latest European Standard, EN12953 for a design pressure. With the exception of the redipac range, all boilers are of Three-pass conventional firetube wetback design with spiral tubes in both tube passes. Flanged end-plates in place of flat end-plates are features on selected boilers to eliminate tee-butt weld joints. This will reduce susceptibility to corrosion fatigue and extend boiler life. Latest spiral-tube technology is used throughout the boiler ranges with heat transfer up to 100% greater than normal plain tubes this feature reduces gas outlet temperature to only 15 deg C above steam saturation temperature offering a thermal efficiency in the case of coal fired boilers. ZG Boiler energy management system to increase efficiency is a feature on coal fired boilers reducing operating and maintenance costs significantly.
Boiler development
The development of firetube shell boilers and associated equipment is carried out within the Technical Department. This covers oil, gas, coal and wood-fired boilers and low and high voltage electrode boilers.
Exports
As a world-class, internationally competitive industrial boiler manufacturer in the export market ZG is a major player in the globalization of South African industry. A network of agents and offices throughout South America, the Middle East and sub-Saharan Africa and Asia supports this export program-me.
Upgrades
For improved boiler plant efficiency either through increased steam output or a reduction in fuel usage, ZG offers customers on-site advice and upgrading programmes. ZG boilers are designed to facilitate conversions where the customer wishes to change his boiler plant fuel to oil, gas or a mixture. Engineered solutions are offered and the necessary conversion carried out on site with minimum downtime.
Industrial Water tube Boiler Services
After Sales Service
Metallurgical Services
Project Management
• Supply and installation of new watertube boilers
• Retrofit, overhaul, repair and maintenance
• Installation of wet gas scrubbers
• Spares service - fast, nation-wide
• Project management
• Reliability Studies
• Boiler Inspections
• Metallurgical Surveys
This service includes the preparation of industrial water tube boilers for statutory inspections, re-tubes, and burner and stoker repairs as well as on or off site conversions from/to oil, gas and coal. Our service teams also handle recommendations regarding maintenance and service contracts for trouble-free running of plant.
As a leader in the field of boiler technology, the company has extensive materials engineering facilities for both in-plant and on-site investigations. These facilities enable detailed investigations to be conducted to establish the metallurgical condition of materials and failure analysis. The methods involved range from hardness inspections and thickness checks to detailed metallographic examination using replication techniques.
In addition to supplying standard boilers, we project manage and engineer large turnkey boiler plant installations which include civil, electrical, instrumentation, fuel and ash handling flue gas clean-up and pre-boiler plant. The project management objectives of directing and co-coordinating human and material resources throughout the life of the project are achieved by utilizing modern management techniques to cover the predetermined objectives of scope, cost, time, quality and participant satisfaction. A project manager is appointed for each project and has responsibility for the overall management of the project.
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