Box-type furnace

Firing of Enamels. Firing can be carried out in intermittent box-type furnaces or continuous furnaces. The dryer and the furnace form one continuous unit or function as separate units in the continuous firing process. Most industrial furnaces are fiber-lined (low thermal mass), which lowers cost and downtime between firing schedules. 

The feed is desulfurized and mixed with process steam before entering the steam reformer. This steam reformer is a top-fired box type furnace with a cold outlet header system developed by Krupp Uhde. The reforming reaction occurs over a nickel catalyst. Outlet reformed gas is a mixture of H2, CO, C02 and residual methane. It... 

Multiburner tests involve two or more burners simultaneously firing in a furnace. These types of tests are common in ethylene applications where one or more wall-fired burners on the furnace floor and several radiant wall burners are firing simultaneously. Thus, the furnace needs to be tall enough to approximate the dimensions of a cracking furnace. It is also common to test the radiant wall burner individually prior to the multiburner test. For this reason, small box type furnaces are available to accommodate the small firing rate of a horizontally installed radiant wall burner. 

In top- and bottom-fired box type furnaces, tubes are arranged in a number of parallel rows with the burners between the tube rows either in the top or bottom. The flue gas is taken out in the bottom of the top-fired and in the top of the bottom-fired reformer. These t5 es have fewer burners. 

EXHIBIT 7-17 Convection Section Tube Removal in 3 Box-Type Furnace... 

This section details the piping layout of circular and box-type furnaces. Although such special features as snuffing steam are actually required for both heaters, they are explained for one application only. 

Exhibit 7-40 is a sample piping and instrumentation diagram for a box-type furnace. This heater has 6-in produa inlet and outlet leads, a swing ell used for decoking, a conveaion steam coil, and a burner management system. Exhibit 7-4l provides an overall view of the furnace in this example and indicates the major parts of the furnace. 

EXHIBIT 7-42 Decoking Operation for a Box-Type Furnace 6WIKJ61... 

Equations (18-2) to (18-6) apply to any conventional box-type furnace with radiant tubes any number of rows deep, with or without air preheat or flue-gas recirculation, and with any normal percentage of excess air. The factor a may be obtained from Fig. 18-3 but for normal tube arrangements, such as two rows of tubes spaced at a center to center of about twice the tube diameter, the value of a is 0.986. The relative absorption... 

Fig. 13. Radiant section of a Kellogg box-type steam reforming furnace.

One vendor states that they provide a down-flow, down-fired, box-type reformer furnace design for capacities above 10 million SCFD of dry synthesis gas. They provide a cylindrical-type reformer furnace design for capacities below 9 to 10 million SCFD of dry synthesis gas167. 

Cost of process furnaces, box type with horizontal radiant tubes. 

In final assembly braze strips (silicon-aluminum alloy) are fastened to the edges of the fuel plates by bending over the ends. The brazing strip is then fluxed, and the fuel plate is inserted between the side plates, which are held in a jig. After all plates are inserted and the combs are in place, the jig is closed,to put the side plates into correct position. The whole assembly is then dried and charged into a box type electric furnace for preheating to SOO. C. After being preheated, the assembly is placed in another furnace at llOO C to accomplish final brazing. 

Indirect-fired heaters of the box type, also called fired heaters, process heaters, and furnaces, are commonly used to heat and/or vaporize non-reacting process streams at elevated temperatures beyond where steam is normally employed. The fuel for combustion is either gas or... 

Figure 7.11 (a) A roof-fired box-type reforming furnace, (b) Detail of top part of a... 

Furnaces, also referred to as heaters, are one of the main pieces of equipment in a process complex. A furnace may raise the temperature of a gas or hydrocarbon liquid to meet specific processing needs or, in the case of pyrolysis and reformer furnaces, cause a chemical or physical change to the medium. A circular or box-type configuration is primarily used variations to each design are covered throughout this chapter. In addition, because of the various types of furnaces, this chapter covers some basics of furnace design and discusses how to approach a piping layout as it relates to maintenance, operation, and safety. 

The furnace and thermostatic mortar. For heating the tube packing, a small electric furnace N has been found to be more satisfactory than a row of gas burners. The type used consists of a silica tube (I s cm. in diameter and 25 cm. long) wound with nichrome wire and contained in an asbestos cylinder, the annular space being lagged the ends of the asbestos cylinder being closed by asbestos semi-circles built round the porcelain furnace tube. The furnace is controlled by a Simmerstat that has been calibrated at 680 against a bimetal pyrometer, and the furnace temperature is checked by this method from time to time. The furnace is equipped with a small steel bar attached to the asbestos and is thus mounted on an ordinary laboratory stand the Simmerstat may then be placed immediately underneath it on the baseplate of this stand, or alternatively the furnace may be built on to the top of the Simmerstat box. 

Steam-generating equipment is similar to a gas-fired furnace in that fuel gas is most always the heating source of the steam generator. The furnace is generally an A-type tube-shaped frame inside a rectangular box in which the steam is on the tube side. 

Carbon vessels are filled with the powder blend. Depending on the furnace type, either boats or boxes made of dense graphite are used. The vessels are covered with a graphite cover to avoid any contamination, and pass through the furnace. 

Furnace type Box shape, walking-beam type... 

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