Continuous Liquid Heating Furnaces

CONTINUOUS LIQUID HEATING FURNACES 4.7.1. Continuous Liquid Bath Furnaces... 

Carbon disulfide. Carbon disulfide (CS2) is produced commercially by the direct union of sulfur vapor and hot carbon at considerably elevated temperatures in an enclosed electric furnace. The reaction must be carried out in the absence of air. Solid sulfur and carbon (usually in the form of coke) are fed continuously into the furnace, which is heated electrically to a temperature sufficient to vaporize the sulfur and to maintain the carbon at a temperature such that combination occurs when the sulfur vapor comes into contact with the solid carbon. Since carbon disulfide is a low-boiling-point liquid (46°C), it passes out of the furnace as a vapor, which is conducted into a condenser. Although the resulting pale-yellow liquid may be purified by distillation, the crude product is used directly for many purposes. 

Storage of heat is a temporary operation since perfect thermal insulators are unknown thus, heat is absorbed in solids or liquids as sensible or latent heat to be released later at designated times and conditions. The collection and release of heat can be achieved in two modes on a batch basis, as in the checkerbrick regenerator for blast furnaces, or on a continuous basis, as in the Ljungstrom air heater. 

In catalytic incineration, there are limitations concerning the effluent streams to be treated. Waste gases with organic compound contents higher than 20% of LET (lower explosion limit) are not suitable, as the heat content released in the oxidation process increases the catalyst bed temperature above 650 °C. This is normally the maximum permissible temperature to which a catalyst bed can be continuously exposed. The problem is solved by dilution-, this method increases the furnace volume and hence the investment and operation costs. Concentrations between 2% and 20% of LET are optimal, The catalytic incinerator is not recommended without prefiltration for waste gases containing particulate matter or liquids which cannot be vaporized. The waste gas must not contain catalyst poisons, such as phosphorus, arsenic, antimony, lead, zinc, mercury, tin, sulfur, or iron oxide.(see Table 1.3.111... 

A breach of these emission levels is an offence under Section 2(2) of this Act. Best practicable means may be used as a fence against this action, and the Regulations prescribe to which classes of appliance they apply. Schedule 1 furnaces are rated by heat output and are boilers or indirect heating appliances where the material heated is a gas or a liquid. The maximum continuous rating concerned are from 825,000 to 475 million BTUs. 

Binary liquid metal systems were used in liquid-metal magnetohydrodynamic generators and liquid-metal fuel cell systems for which boiling heat transfer characteristics were required. Mori et al. (1970) studied a binary liquid metal of mercury and the eutectic alloy of bismuth and lead flowing through a vertical, alloy steel tube of 2.54-cm (1-in) O.D., which was heated by radiation in an electric furnace. In their experiments, both axial and radial temperature distributions were measured, and the liquid temperature continued to increase when boiling occurred. A radial temperature gradient also existed even away from the thin layer next to the... 

For purification of the product, tubes A and B are cleaned, dried, and reassembled with a dry glass-wool insert in B. Tube C, containing the initially formed product, is attached to tube B as shown in Fig. 2. The system is evacuated and this time left open to the vacuum. The two furnaces are separated by ca. 1.5 cm. Furnace I is heated to 80° and furnace II to 130 to 140°. Sublimation is allowed to continue until all the titanium(IV) iodide has left tube C (12 to 16 hours). The purified product crystallizes in tube B at the separation of the two furnaces. The major impurity, iodine, crystallizes in tube A and in the liquid-nitrogen trap. A fluffy tan residue of negligible weight (0.04 to 0.06 g.) remains in tube C. If desired, further purification can be accomplished by moving tube B farther into furnace II, which results in a second sublimation of the product. 

Spray pyrolysis routes have been extensively investigated to prepare Pt-based catalysts. Typically, a liquid feed of metal precursor and carbon is atomized into an aerosol and fed into a continuous furnace to evaporate and heat-treat to form a collectable powder. The method has good control over final aggregate particle size and metal particle size distributions, as well as producing powder without further isolation or separation. Hampton-Smith et al. have reviewed efforts of Superior MicroPowder (now Cabot Fuel Cells) in this area. ... 

Muffle Furnaces or Retorts of Graphite or Silicon Carbide. The metal is fed into the furnace either batchwise as a solid or continuously as a liquid. The heat of vaporization is supplied by heating the outside of the retort with a burner. The nonvolatile residues (iron and lead in the case of dross from smelting) accumulate in the retort and must be removed at intervals. This is facilitated by tipping the retorts. 

---