Refractory linings selection

DESIGN PARAMETERS WHICH AFFECT REFRACTORY LINING SELECTION... 

The secondary reformer in an ammonia plant is a carbon steel vessel with a dual layer refractory lining. Internal temperatures reach -2,000°F (1,090°C) from burning as a result of air added through a burner at the top of the vessel to the feed gas (hydrogen, carbon monoxide, carbon dioxide, and steam). The burner is a refractory-lined device that is subject to failure if not carefully designed. Quench steam generators have refractory-lined inlet channels and tube sheets. Tubes are often made of carbon steel because the heat transfer from the steam on the outside of the tube is markedly better than that from the synthesis gas inside the tube. As a result, the metal temperature closely approaches the temperature of the steam. The inlet ends of the tubes are protected from the inlet gas by ferrules, usually made of type 310 (UNS S31000) SS with insulation between the ferrule and the tube. The tube material should be selected... 

Enlisting refractory consultants early in process design work is a very wise step. The designer is frequently faced with early decisions between vastly different approaches, all of which appear to be equal in their effectiveness. Consequently, the least expensive route is selected in an effort to keep costs down. Where refractory linings are involved, a seemingly insignificant decision may have quite an impact on refractory performance and subsequent process reliability. 

The limestone, fuel and refractory linings used for lime burning should be selected with care in the context of the kiln design and the required quicklime quality. For a new installation, the kiln supplier should be able to test and assess the suitability of the raw materials. For an existing lime works, the potential effects of proposed changes in the limestone, fuel or refractories should be assessed with care. 

Selecting the most appropriate refractory lining for a lime kiln is important for the economic viability of the installation. The refractory at the hot face has to provide adequate performance with respect to ... 

Many processes operate at temperatures exceeding 700 "C and require both specialized metals—stainless steel. Inconel, Hastelloy, etc.—as well as refractory materials to insulate the metal from the extreme temperatures. Refractory linings and bricks are the most common insulating materials for industrial vessels. In selecting a refractory lining, its resistance to thermal shock... 

In any refractory lined system it is required to determine the heat loss and skin temperatures in order to do a proper design of the metal containment (shell) as well as to determine the selection and effectiveness of the refractory itself. 

Humbold K. Boron compounds in carbon-bonded refl actories. Ceram Ind 1995 47-50. Brezny B. Refractory materials selection Effects of brick properties on BOF lining life. In Rigaud M, Landy RA, eds. Pneumatic Steelmaking Volume Three, Refractories. Warrendale, PA ISS, 19% 116 125. 

Although the efficacy of tricyclic antidepressants in the treatment of unipolar depression is beyond reproach, the side-effect profile of these agents makes them less desirable as first-line therapeutic agents. Introduction of selective serotonin reuptake inhibitors (SSRIs) such as fluoxetine, paroxetine, sertraline, citalopram and fluvoxamine in the past decade has revolutionized the treatment of depression universally. The side-effect profile of SSRIs, such as nausea, diarrhea and sexual dysfunction, is considerably more benign than that of tricyclic drugs. Multiple controlled trials have proven the efficacy of SSRIs vs. placebo (Nemeroff, 1994). Recently, a number of SNRIs (serotonin and noradrenaline reuptake inhibitors) and so-called atypical antidepressants have been marketed that may have additional advantages over SSRIs, such as more rapid onset of action (venlafaxine. mirtazapine) and low sexual side-effect potential ( bupropion, nefazodone). Additionally, it appears that venlafaxine may be more efficacious in cases of treatment-refractory depression (Clerc et al., 1994 Fatemi et al., 1999). Finally, in a recent report (Thase et al., 2001),... 

Operating conditions in partial oxidation reactors and steam reformers vary considerably - depending on the feedstock that is being used. An operating temperature of 1400°C (i.e., the temperature of the inner surface of the lining) is not critical for many refractory materials. However factors other than temperature determine the refractory selection and the refractory design. 

The cyclones in both unit types are lined with erosion resistant refractory. The cydones in the reactors are usually made of carbon steel the cyclones in the regenerators are made of either 2%Cr-l Mo or type 304 (UNS S30400) or 321 (UNS S32100) stainless steel (SS). Oxidation resistance and creep strength, rather than sulfur attack, govern the selection of the cyclone material. 

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