Abstract

Expandable graphite (EG) is an intumescent additive known to improve fire properties of various materials. Intumescent fire retardant (IFR) based on EG is a protection method for flammable materials taking the attention of researchers in the past few years (Xie et al., 2000). New studies indicate that EG is a good source of carbonization agent for effective and environmentally friendly intumescent systems (Feng et al. 2013). Although EG is used in a growing number of IFR systems as a blowing agent that will suppress flammable gases up to 75%, while reducing the flame spread index, its application to cellulosic material is not so popular in the cellulose industry today (Krassowski et al., 2012). The current study focuses on flammability, concerning cellulose modified material(CMM). The objective of this work was CMM encrusted with EG. The general aim of the research was to determine its basic fire resistance properties. The scope of the research included measurement of the following parameters: time to ignition (Ti), time to flame out (Tf), total heat peak (THR) and mass loss (ML). Samples of CMM sheets were manufactured with the use of hydropulper and rapid-koethen devices. Two types of EG (i.e. ES20 C200 and ES100 C10) were used. Sodra Black Cellulose fibres (700 kg/N3) was used in this experiment. Cellulose milling time was 30 min. and drying time of 40 min. The drying temperature of the final sheets was controlled and kept at 930C to avoid graphite activation. Final sheets were conditioned at room temperature at 200C and relative humidity 60%. With heat flux of 35 kW/m2 , all samples were tested on MLC apparatus. The addition of EG was found to increase the flame retardant effectiveness of cellulosic material. Although Ti for all CMM species were lower than that of control samples, this fact actually favored the promotion of char forming, which led to a longer combustion process for all CMM.

Abstract

Effluent streams from the Modular Caustic-Side Solvent Extraction Unit (MCU) will transfer to the tank farms and to the Defense Waste Processing Facility (DWPF). These streams will contain entrained solvent. A significant portion of the Strip Effluent (SE) pipeline (i.e., acid stream containing Isopar{reg_sign} L residues) length is within one inch of a sludge stream. Personnel envisioned the sludge stream temperature may reach 100 C during operation. The nearby SE stream may receive heat from the sludge stream and reach temperatures that may lead to flammability issues once the contents of the SE stream discharge into a larger reservoir. To this end, personnel used correlations from the literature to estimate the maximum temperature rise the SE stream may experience if the nearby sludge stream reaches boiling temperature. Several calculation methods were used to determine the temperature rise of the SE stream. One method considered a heat balance equation under steady state that employed correlation functions to estimate heat transfer rate. This method showed the maximum temperature of the acid stream (SE) may exceed 45 C when the nearby sludge stream is 80 C or higher. A second method used an effectiveness calculation used to predict the heat transfer rate in more » single pass heat exchanger. By envisioning the acid and sludge pipes as a parallel flow pipe-to-pipe heat exchanger, this method provides a conservative estimation of the maximum temperature rise. Assuming the contact area (i.e., the area over which the heat transfer occurs) is the whole pipe area, the results found by this method nearly matched the results found with the previous calculation method. It is recommended that the sludge stream be maintained below 80 C to minimize a flammable vapor hazard from occurring. « le Document type: Report