Preheat diagram

Fig 1. Schematic diagram of the ICFB gasifier. 1. steam generator, 2. flowmeter, 3. orifice flowmeter, 4. air preheater, 5, gas plenum, 6. draft tube, 7. orifice, 8. gas separator, 9. freeboard, 10. screw feeder, 11. mono-pump, 12. sludge feed nozzle, 13. cyclone, 14. condenser, 15. collector, 16. filter, 17. ID fan. 

Prepare a heat balance diagram of the preheater vaporiser superheater-reactor... 

A flow diagram indicating notation is shown in Figure 21.11 for a three-stage FBCR in which the reaction A products takes place. The feed enters at T0 and m kg s-1, or, in terms of A, at Fao and fAo = 0. The feed is split at S so that a fraction r enters stage 1 alter passing tough the preheater El, where the temperature is raised from Ta to Tol. A subsequent split occurs at S2 so that a feed fraction r2 mixes with the effluent... 

Figure 6.5 provides a detailed process flow diagram of the system. During normal operation air enters the compressor and is compressed to 3 atmospheres. This compressed air passes through the recuperator, where it is preheated and then enters the SOFC. Pressurized fuel from the fuel pump also enters the SOFC, and the electrochemical reactions take place along the cells. The hot pressurized exhaust leaves the SOFC and goes directly to the expander section of the gas... 

On a Mollier diagram like that with Example 4.1, it is clear that expansion to a low pressure may lead to partial condensation if insufficient preheat is supplied to the inlet steam. The final condition after application of the efficiency correction is the pertinent one, even though the isentropic point may be in the two-phase region. Condensation on the blades is harmful to them and must be avoided. Similarly, when carbon dioxide is expanded, possible formation of solid must be guarded against. 

Figure 4.2. Combustion gas turbine arrangements and their thermodynamic diagrams, (a) Basic unit with PV and TS diagrams, (b) Unit with an air preheater and TS diagram.

Two types of polymerization units are designed by Universal Oil Products Company. The U.O.P. Reactor-type unit contains the catalyst in tubes which are surrounded by water in a jacket for the purpose of removing the heat liberated by the exothermic polymerization reaction. The steam generated in the water jacket normally is used to preheat the feed. A feed-to-products heat exchanger furnishes the remaining heat requirements. Conventional depropanizer and debutanizer columns are used to fractionate the product. Figure 3 shows a flow diagram of a reactor type of polymerization unit. 

The U.O.P. Chamber-type unit contains the catalyst in a reactor in which the catalyst is separated into a number of beds. Temperature control is accomplished by quenching between the beds with cold liquid effluent and by recycling spent propane and butane effluent into the reactor feed. This is not a heat-balance operation and a preheater using an outside source of heat is required in addition to the feed-to-products exchanger. A depropanizer and debutanizer are usually used to fractionate the effluent. Figure 2 shows a flow diagram of a chamber type of polymerization unit. 

A typical flow diagram is shown in Fig. 18.13 The desalter operation is incorporated into the preheat train of the crude distillation unit to conserve energy. Depending on the characteristics of the hydrocarbon feedstock,... 

A typical flow diagram of a two-stage crude oil distillation system is shown in Fig. 18.14. The crude oil is preheated with hot products from the system and desalted before entering the fired heater. The typical feed to the crude-fired heater has an inlet temperature of 550°F, whereas the outlet temperature may reach 657-725°F. Heater effluent enters the crude distillation (CD) column, where light naphtha is drawn off the overhead tower. Heavy naphtha, kerosene, diesel, and cracking streams are sidestream drawoffs from the distillation column. External reflux for the tower is provided by several pumparound streams.12... 

Schematic diagram of a natural gas expansion station. preheater for pressure relief valve...

Our first and foremost concern is to dissipate the exothermic heat away from the reactor. This requires that we have the ability to bypass the feed preheaters such that excess heat from the process is not carried back with the reactor feeds. We introduce a set of bypass valves along with temperature controllers as shown in Fig. 5.15, We have elected to install the bypass valves on the cold side to lower the investment cost and facilitate maintenance. We also get better temperature control of the cold stream leaving the preheaters. In Fig. 5.15 we show the stream temperatures at the valve inlets as well as the control points. These data were obtained from the T-H diagram provided by Terrill and Douglas (1987a). Even though we bypass on the cold side, we see that one of the bypass valves has to operate at a temperature over 330°C,... 

Fig. 3.2 Schematic diagram of a four-stage cyclone-type suspension preheater. P indicates the position at which a precalciner burner may be incorporated.

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