Refractories ring the changes wahl refractory solutions. These standard dryout schedules are generic and require temperature monitoring rarely found at power plants, where. They are typically composed of oxides of the following materials. Important issues such as burner size and location, exhaust location, air volume and velocity also need to be addressed. Then uncover and allow to dry naturally for 2 3 days at room temperature approx 20 o c before taking out of the mould. Drying refractory is critical for strong, longlasting refractory applications.
The information presented in this book is for general educational use only. These are guidelines for the installation quality control of monolithic refractory linings and may be used to supplement owner specifications. Drying refractory in steamgenerating boilers insulation outlook. Table 1 compares installation times over a 24month life cycle for sifca nose blocks and a conventional refractory castable nose ring. It does not contain recommendations for any particular refractory for any particular use.
Modern design technology requires the installation of large amounts of expensive refractory for high temperature process. 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. The key properties of monolithic refractory dryout performance, such as fluid permeability and mechanical strength, were also determined. Issues such as burner size and placement, exhaust location, air volume, air velocity, thermocouple placement, etc.
Magnesia refractory dryoutmanaging the risk of hydration article pdf available in journal south african institute of mining and metallurgy 1116. Drying refractory in steamgenerating boilers insulation. Drying out monolithic refractories gulf coast combustion. Refractory dryout our expertise in these areas ensures maximum flexibility and minimum downtime. The best 100 year old family potato candy recipe with alan lubeski duration.
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. Boiler refractory dryout courtesy of rentech boiler 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. For the dryout of a refractory lining external high velocity burners are used. The drying behavior of a hydratable aluminabonded hab refractory castable was evaluated by thermogravimetric tests and compared with an ultralow cement composition cac.
Longer period of low temperature drying causes more even heat distribution. The mortar needs to dry out completely prior to exposure to fire. While heating, there must be free air flow over the system to ensure removal of moisture. Drying out monolithic refractories refractories are heatresistant materials used for the retention of substances at high temperatures in furnaces, reactors and other processing units. Mixers and tools must be clean and free of any old castable, cement or foreign material that may contaminate the mix. Important considerations for refractory dryouts, startups. Properly prepared molds of mold mix 6 will resolve the finest details and possess good strength. 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. 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. 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. Explosive spalling of low cement castable refractories a.
One burner unit exists of the mobile burner with the extended nozzle, the combustion fan, regulation flap for the combustion air, the connecting air. It comes as a paste, which is applied to a suitably prepared pattern and hardens on drying. Dry out must not be confused with curing, which is the process of keeping the refractory material wet or the surrounding atmosphere humid for. This dryout program is given for the average amount of material as an information guide. Harbisonwalker handbook of refractory practice disclaimer.
These external burners are fired with light weight oilgas and will be installed in openings like manholes or doors. Alan lubeski thegrizzlybearking recommended for you. This property is important when the refractory is in contact with molten charge and slag. For this comparison, both options begin with the removal of a conventional castable nose ring.
Various capacity of oil and gas burners, including high velocity burners up to 5,000,000 kcalhr. Secondary reformer refractory baking and dry out cycle requires very slow and controlled heating of refractory. Refractory has always been an integral part of steamgenerating boilers. I am agree with ts1979, every refractory lining especially for monolithic castable lining has to cured for 24 hours minimum before dryout process. 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. 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. If not cured completely, the material will crack due to the pressure caused by water evaporating within in the mortar. The api 936 refractory personnel certification is designed to identify candidates possessing the knowledge of api std 936 refractory installation quality control guidelines. Refractory mortar may also be used when parging a smoke chimney chamber. A high velocity hot air burner is recommendable for heatingup. The values and the information given are subject to. 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. Pdf drying stages during the heating of highalumina.
For many refractory installations, the dryout portion of the project can be the most frustrating. Curing is necessary to prevent moisture loss during the setting of the material. 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. You should apply our company for the different refractory labels, amounts and widths. It is not intended as, and should not be taken as, a warranty of any kind, including but not limited to a warranty of. The refractory material was not normally thermally cured at the factory.
With gulf coast combustions refractory dry out knowledge and expertise, you and your clients will get a longlasting life on your refractory. Course content abstract refractories are heat resistant materials used in almost all processes involving high temperatures andor corrosive environment. Vitcas refractory castable grade 1600refractory concrete. 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. Any material of this nature will affect the set time andor the ultimate strength of the castable.
These are typically used to insulate and protect industrial furnaces and vessels due to their excellent resistance to heat, chemical attack and. Rcf is a refractory ceramic fibre material, also know as asw alumino silicate wool. In addition to being resistant to thermal stress and other elements induced by heat, refractories are usually required to withstand physical wear and corrosion. Our refractory dry out services is consist for the following. Spar recommends consulting an experienced dry out company. Pdf magnesia refractory dryoutmanaging the risk of. Refractory baking and dry out cycle requires very slow and controlled heating of refractory as recommended by the refractory manufacturers. Boiler refractory dry out is to ensure proper drying, curing of refractory applied on furnace and other components. The steam always found its way out and the dryouts were completed without any detrimental effect to the refractory lining. Pdf secondary reformer refractory dry out operation prem. 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. Pdf secondary reformer refractory dry out operation. Thermal stresses will be produced if heating rate is too rapid.
Thermocouples during the refractory installation is the best time to install. Pdf magnesia refractory dryoutmanaging the risk of hydration. The curing and firing of refractory castables densecretes and litecretes. The dry out of refractory involves more than following a heating schedule. Zircar mold mix 6 is a refractorymolding compound designed to allow replication of threedimensional objects in glass and bronze. The majority of refractory cements are a combination of clinker and an aggregate material. National heat has over ten years of experience undertaking refractory dry outs for many clients around australia. Refractory cement is a material that retains its high strength properties at extremely high temperatures. 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. Drying behavior of hydratable aluminabonded refractory. 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.
Refractory dry out the key to a long refractory life is a dryout using gccs high velocity gas combustion systems. 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. Dry castable refractory products, and wetdry mortars. Heatingup for drying to the operational temperature of the installed monolithic refractory lining shall be carefully carried out because rapid heating causes cracks. The refractory material was not normally thermally cured at the. Allow a minimum of 7 to 10 days before heat is applied. Refractories are inorganic, nonmetallic, porous, and heterogeneous. Refractory dry out procedures boiler furnace scribd. Harbisonwalker handbook of refractory practice 2005. The refractory usually undergoes considerable chemical changes, during initial heating. Preheating is necessary to dry out all the excess moisture which is retained within it. Installed refractory linings and castings containing calcium aluminate cement binders should be cured prior to drying. Heating procedure for castable refractories kiltas refrakter. The correct application of heat curing and controlled release of water in the castable is very important for the life time.
Controlled heating, through these reactions ensures maximum strength. 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 dry out of convection and breaching section. 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. The combined efforts of refractory manufacturer, installer and dryout contractor result in optimal refractory performance. Whilst the values and application information in this product data book are typical, they are given for guidance only. The dry out of refractory entails much more than just following a heat up schedule. Proper refractory dry out is key to optimum service life. Boiler refractory dry out is to ensure proper drying, curing of. Refractory dryouts national heat treatment division.