Horizontal combustion

Methyl alcohol (100 c.c.) is placed in a flask which is kept at a temperature of 40°, aud connected to a horizontal combustion tube in which a roll of copper foil (5 cm. long) is placed, The other end of the combustion tube is connected to a condenser and a well cooled receiver. 

The muffle was a horizontal combustion chamber lined with refractory material. The German Norms for the construction and operation offurnaces for the cremation of human corpse enacted in 1937 prescribed the following minimal measures for such a muffle width 900 millimeter height 900 millimeter length 2500 millimeter.52... 

Horizontal combustion chamber with a water-cooled shell. 

The Wislicenus process (see p. 24), for example, may be conducted as follows. Several iron boats containing sodium metal are placed in a horizontal combustion tube and heated in nitrogen to 250-300°C the gas is then changed to dry ammonia until the molten metal is converted to sodamide. The temperature is then lowered to 170-190°C and the gas changed to nitrous oxide, N2O, until no more ammonia is detected in the waste gases. The crude product (sodium azide + sodium hydroxide) is leached with water and after filtering concentrated to incipient crystallization. Some azide is retained in the caustic liquid, from which it may be precipitated with alcohol. 

In the Mitsubishi organic halogen measurement system, chloro and bromo compounds in the environment (air, water) are adsorbed in columns tilled with activated carbon and then heated at 900°C in a horizontal combustion tube in an oxygen atmosphere. The hydrogen chloride and hydrogen bromide produeed are introduced into the automatic titration cell and determined coulometrically with silver ions. 

The combustion tube. The oxygen is led through the side-arm G (Fig. 85) into the combustion tube L via the horizontal side-arm H which is fused into the combustion tube about 4 cm. from the end (the joint between G and H is also made with impregnated rubber tubing with the two glass tubes touching inside the rubber). The position of H thus allows the combustion... 

Some beehive ovens, having various improvements and additions of waste heat boilers, thereby allowing heat recovery from the combustion products, may stiU be in operation. Generally, however, the beehive oven has been replaced by waH-heated, horizontal chamber, ie, slot, ovens in which higher temperatures can be achieved as well as a better control over the quality of the coke. Modem slot-type coke ovens are approximately 15 m long, approximately 6 m high, and the width is chosen to suit the carbonization behavior of the coal to be processed. For example, the most common widths are ca 0.5 m, but some ovens may be as narrow as 0.3 m, or as wide as 0.6 m. 

The first of these reactions takes place at temperatures of about 150°C, the second reaction proceeds at about 550—660°C. Typical furnaces used to carry out the reaction include cast-iron retorts the Mannheim mechanical furnace, which consists of an enclosed stationary circular muffle having a concave bottom pan and a domed cover and the Laury furnace, which employs a horizontal two-chambered rotating cylinder for the reaction vessel. The most recent design is the Cannon fluid-bed reactor in which the sulfuric acid vapor is injected with the combustion gases into a fluidized bed of salts. The Mannaheim furnace has also been used with potassium chloride as the feed. 

Fig. 12. Combustion turbine engine simple cycle (a) schematic of plant and (b) thermodynamics, where the horizontal lines correspond to the pressure...

Large sulfuric acid plants are based on spray burners, where the sulfur is pumped at 1030—1240 kPa (150—180 psig) through several nossles iato a refractory-lined combustion chamber. An improved nossle, resistant to plugging or fouling, has been iatroduced (256). The combustion chambers are typically horizontal baffle-fitted refractory-lined vessels. The largest plants ia fertiliser complexes bum up to 50 t/h of sulfur. 

Indirect (French) Process. Ziac metal vapor for burning is produced ia several ways, one of which iavolves horizontal retorts. Siace all the vapor is burned ia a combustion chamber, the purity of the oxide depends on that of the ziac feed. Oxide of the highest purity requires special high grade ziac and less-pure products are made by blending ia Prime Western and even scrap ziac. 

A calcining kiln is a horizontal steel cylinder, slightly sloped to help the coke move forward and lined with refractory brick. The raw coke is fed at the upper end, natural gas or oil is burned at the lower end, and the combustion gas flows through the kiln above and against the coke stream. 

When used for ceramic heating, furnaces are called Idlus. Operations include drying, oxidation, c cination, and vitrification. These Idlus employ horizontal space burners with gaseous, hquid, or solid fuels. If product quahty is not injured, ceramic ware may be exposed to flame and combustion gases otherwise, muffle Idlus are employed. Dutch ovens are used frequently for heat generation. 

The circular burner shown in Fig. 27-17 is widely used in horizontally fired furnaces and is capable of firing coal, oil, or gas in capacities as tigh as 174 GJ/h (1.65 X 10 Btii/h). In such burners the air is often swirled to create a zone of reverse flow immediately downstream of the burner centerline, which provides for combustion stability. 

Vei tical cylindrical cross-tube convection heaters are similar to the preceding type except for a horizontal convective tube bank above the combustion chamber. The design is economical with a high efficiency and is usually selec ted for higher-duty applications 11 to 210 GJ/h (10 to 200 10 Btu/h). 

Honzontal-tube cabin heaters position the tubes of the radiant-section-coil horizontally along the walls and the slanting roof for the length of the cabin-shaped enclosure. The convection tube bank is placed horizontally above the combustion chamber. It may be fired From the floor, the side walls, or the end walls. As in the case of its vertical cylindrical counterpart, its economical design and high efficiency make it the most popular horizontal-tube heater. Duties are 11 to 105 GJ/h (10 to 100 10 Btu). 

Schematic elevation sec tions of a vertical cylindrical, cross-tube convection heater a horizontal-tube cabin heater and a vertical cylindrical, helical-coil heater are shown in Fig. 27-51. The seven basic designs and some variations of them are pictured and described in the reference cited above and by R. K. Johnson Combustion 50(5) 10-16, November 1978).

The radiant section tube coils of horizontal fired heaters are arranged horizontally so as to line the sidewalls and the roof of the combustion chamber. In addition, tliere is a convection section of tube coils, winch are positioned as a horizontal bank of tubes above the combustion cham her. Nonnally the tubes are fired vertically from the floor, but they can also be fired horizontally by side wall mounted burners located below the tube coil. Tins economical, high dficiency design currently represents the majority of new horizontal-tube-t1icd heater installations. Duties run from 5 to 250 MMBtu/hr. Six types o) horizontal-tube-fired heaters arc-shown in Figure 3-21. 

These formerly involved the use of banks of externally heated, horizontal retorts, operated on a batch basis. They were replaced by continuously operated vertical retorts, in some cases electrically heated. Unfortunately none of these processes has the thermal efficiency of a blast furnace process (p. 1072) in which the combustion of the fuel for heating takes place in the same chamber as the reduction of the oxide. The inescapable problem posed by zinc is that the reduction of ZnO by carbon is not spontaneous below the boiling point of Zn (a problem not encountered in the smelting of Fe, Cu or Pb, for instance), and the subsequent cooling to condense the vapour is liable, in the presence of the combustion products, to result in the reoxidation of the metal ... 

The horizontal line at the bottom of the pressure-volume diagram of Figure 4 traces the other tv o strokes of the four-stroke cycle. On the exhaust stroke, from 5 to 6, the rising piston expels most of the remaining combustion products from the cylinder. On the intake stroke, from 6 to 7 (= 1), the descending piston inducts a fresh charge for repetition of the cycle. The net thermodynamic work developed in this cycle is proportional to the area enclosed by the pressure-volume diagram. In the ideal case, both the exhaust and intake strokes occur at atmospheric pressure, so they have no effect on the net output work. That justifies their exclusion from the thermodynamic representation of the ideal Otto... 

This is a horizontal shell boiler where the gas-reversal chamber from the combustion tube to the first pass of tubes is external to the rear tube plate and is formed by a refractory lined steel chamber. 

Figure 2.2 Schematic of a modem four-pass, packaged horizontal FT boiler, with low NOx emission, showing path of hot combustion gas flow, and air/combustion gases recirculation system.

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