Refractory has always been an integral part of steamgenerating boilers. Boiler refractory dry out is to ensure proper drying, curing of refractory applied on furnace and other components. Then uncover and allow to dry naturally for 2 3 days at room temperature approx 20 o c before taking out of the mould. Harbisonwalker handbook of refractory practice 2005. Issues such as burner size and placement, exhaust location, air volume, air velocity, thermocouple placement, etc. It does not contain recommendations for any particular refractory for any particular use. Alan lubeski thegrizzlybearking recommended for you. Pdf secondary reformer refractory dry out operation prem. Rcf is a refractory ceramic fibre material, also know as asw alumino silicate wool.
Vitcas refractory castable grade 1600refractory concrete. Refractory cement is a material that retains its high strength properties at extremely high temperatures. Harbisonwalker handbook of refractory practice disclaimer. Refractory dryouts national heat treatment division. Explosive spalling of low cement castable refractories a. Pdf in 2002 the commissioning of an ilmenite smelter on the north coast of south africa was extended by three months due to the failure and. Secondary reformer refractory baking and dry out cycle requires very slow and controlled heating of refractory. Drying behavior of hydratable aluminabonded refractory. Important considerations for refractory dryouts, startups. Refractories ring the changes wahl refractory solutions. Dry out must not be confused with curing, which is the process of keeping the refractory material wet or the surrounding atmosphere humid for. National heat has over ten years of experience undertaking refractory dry outs for many clients around australia.
This property is important when the refractory is in contact with molten charge and slag. The refractory usually undergoes considerable chemical changes, during initial heating. The steam always found its way out and the dryouts were completed without any detrimental effect to the refractory lining. These standard dryout schedules are generic and require temperature monitoring rarely found at power plants, where. Drying out monolithic refractories refractories are heatresistant materials used for the retention of substances at high temperatures in furnaces, reactors and other processing units. July 2003 drying stages of highalumina, ultralowcement refractory castables 1147 nevertheless, the similarities among the drying profiles of the different tested samples confirmed that removal. Our refractory dry out services is consist for the following. The values and the information given are subject to. Pdf magnesia refractory dryoutmanaging the risk of hydration. Modern design technology requires the installation of large amounts of expensive refractory for high temperature process. Course content abstract refractories are heat resistant materials used in almost all processes involving high temperatures andor corrosive environment. Refractories are inorganic, nonmetallic, porous, and heterogeneous.
In addition to being resistant to thermal stress and other elements induced by heat, refractories are usually required to withstand physical wear and corrosion. Magnesia refractory dryoutmanaging the risk of hydration article pdf available in journal south african institute of mining and metallurgy 1116. The drying behavior of a hydratable aluminabonded hab refractory castable was evaluated by thermogravimetric tests and compared with an ultralow cement composition cac. Drying refractory in steamgenerating boilers insulation. This dryout program is given for the average amount of material as an information guide.
The curing and firing of refractory castables densecretes and litecretes. An effective dry out procedure, and one carried out in compliance with the manufacturers specification, is the key to ensuring that a furnace operates to both the manufacturers specification and the operators expectations. A high velocity hot air burner is recommendable for heatingup. The mortar needs to dry out completely prior to exposure to fire. New challenges have been identified over recent decades regarding the increasing complexity of the dry out step of refractory castables, mainly due to the advances on the particle size. By utilizing stateoftheart equipment, including digital process controllers, fully proportional fuel actuators, and solidstate features, our engineers are able to provide flexible service that meets the most demanding of specifications. You should apply our company for the different refractory labels, amounts and widths. Installed refractory linings and castings containing calcium aluminate cement binders should be cured prior to drying.
Refractory mortar may also be used when parging a smoke chimney chamber. Hotwork has been offering refractory dryout furnace heatup services to refractory consumers since 1965 and has carried out in excess of 20,000 projects in its history. These are guidelines for the installation quality control of monolithic refractory linings and may be used to supplement owner specifications. The most wellknown problem that can be avoided with proper heatup is the dryout spalling, which is often the result of excessive pressurization of entrapped steam after heating above the ebullition point of water. The correct application of heat curing and controlled release of water in the castable is very important for the life time. Boiler refractory dryout courtesy of rentech boiler systems. Curing is necessary to prevent moisture loss during the setting of the material. Pdf drying stages during the heating of highalumina. Properly prepared molds of mold mix 6 will resolve the finest details and possess good strength. It is not intended as, and should not be taken as, a warranty of any kind, including but not limited to a warranty of.
There have been significant improvements in castable and plastic refractories over the past 35 years through the selection of better raw materials, improved particle sizing, additives, improved bonding materials and improved manufacturing. Boiler refractory dry out is to ensure proper drying, curing of. It comes as a paste, which is applied to a suitably prepared pattern and hardens on drying. The information presented in this book is for general educational use only. The dry out of refractory entails much more than just following a heat up schedule. Brimstone sts limited september 16, 2011 page 3 of 15 than ideal temperatures will require a longer than normal dryout schedule with reduced ramp rates and additional or longer hold points. I am agree with ts1979, every refractory lining especially for monolithic castable lining has to cured for 24 hours minimum before dryout process. Zircar mold mix 6 is a refractorymolding compound designed to allow replication of threedimensional objects in glass and bronze. The dry out of refractory involves more than following a heating schedule. It is often used in applications that require high strength, wear resistance, and thermal resistance. Drying out monolithic refractories gulf coast combustion. Refractory baking and dry out cycle requires very slow and controlled heating of refractory as recommended by the refractory manufacturers. A refractory material or refractory is a material that is resistant to decomposition by heat, pressure, or chemical attack, and retains strength and form at high temperatures. Thermal stresses will be produced if heating rate is too rapid.
It is not uncommon for moisture to be absorbed by the refractory during final stages of inshop fabrication, transit to the job site, and before the upstream combustion products are first passed through the unit. Exporter of refractory dryout services refractory dry out of incinerator services, refractory dry out of pre heater of cement plant, thermal stabilization of turbine rotor and refractory dryout of convection and breaching section. Pdf secondary reformer refractory dry out operation. Longer period of low temperature drying causes more even heat distribution. These are typically used to insulate and protect industrial furnaces and vessels due to their excellent resistance to heat, chemical attack and.
In the steamgenerating industry, refractory materials are used for filling gaps and openings to help keep the fire inside the fire box, for lining ash hoppers wet and dry that collect ash and slag, and for the protection of lower furnace wall tubes inside fluidized bed, cyclonefired, or refusederived fired boilers. Whilst the values and application information in this product data book are typical, they are given for guidance only. Refractory dry out procedures boiler furnace scribd. Spar recommends consulting an experienced dry out company. Allow a minimum of 7 to 10 days before heat is applied. The apparent porosity is the volume of the open pores, into which a liquid can penetrate, as a percentage of the total volume of the refractory. While heating, there must be free air flow over the system to ensure removal of moisture.
Mixers and tools must be clean and free of any old castable, cement or foreign material that may contaminate the mix. Refractory dryout our expertise in these areas ensures maximum flexibility and minimum downtime. One burner unit exists of the mobile burner with the extended nozzle, the combustion fan, regulation flap for the combustion air, the connecting air. Preheating is necessary to dry out all the excess moisture which is retained within it. Proper refractory dry out is key to optimum service life. Any material of this nature will affect the set time andor the ultimate strength of the castable. For this comparison, both options begin with the removal of a conventional castable nose ring. Heating procedure for castable refractories kiltas refrakter. Drying refractory is critical for strong, longlasting refractory applications. Current refractory dryout procedures are not scientifically based and in most cases are excessively long and very expensive.
Dry castable refractory products, and wetdry mortars. Cover with plastic if possible immediately after installation and keep covered overnight. The refractory material was not normally thermally cured at the. Table 1 compares installation times over a 24month life cycle for sifca nose blocks and a conventional refractory castable nose ring. The majority of refractory cements are a combination of clinker and an aggregate material. Important issues such as burner size and location, exhaust location, air volume and velocity also need to be addressed. Dry out, also referred to as bake out, is the process for removing both the mechanical water added during the mixing process and chemical water originally added in manufacturing from the refractory. Refractory dry out the key to a long refractory life is a dryout using gccs high velocity gas combustion systems. Unfortunately, standard refractory dryout schedules, provided by all refractory manufacturers with their products, are difficult to apply to refractory used on a steamgenerating boiler.
The best 100 year old family potato candy recipe with alan lubeski duration. Thermocouples during the refractory installation is the best time to install. For the dryout of a refractory lining external high velocity burners are used. Controlled heating, through these reactions ensures maximum strength. The combined efforts of refractory manufacturer, installer and dryout contractor result in optimal refractory performance. Refractory dry out procedures free download as pdf file. The key properties of monolithic refractory dryout performance, such as fluid permeability and mechanical strength, were also determined. Various capacity of oil and gas burners, including high velocity burners up to 5,000,000 kcalhr. They are typically composed of oxides of the following materials. For many refractory installations, the dryout portion of the project can be the most frustrating. If not cured completely, the material will crack due to the pressure caused by water evaporating within in the mortar. Drying refractory in steamgenerating boilers insulation outlook. It looks like the work is completed, the vessel looks brand new, and there are always intense pressures to fire it up and get production ramped back up after a costly outage.
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