Condensers temperature-heat flow diagram

Mg. 7.4-4 Temperature-heat flow diagrams for a product cooler left) and a condenser right)... 

This is a simple quantitative calculation, so we apply the seven-step method in condensed form. We are asked to determine the change in temperature, A 7 , that accompanies a heat flow. Thermal energy is added to each substance, so we expect an increase in temperature for each case. A diagram similar to Figure summarizes the process ... 

Again, we use a condensed form of the seven-step strategy. A temperature change signals a heat flow. In this example, an increase in the temperature of the aluminum pan means that heat flows from the surroundings (including the stove) to the pan, which represents the system. As in Example, a diagram summarizes the process. 

To evaluate the true temperature difference (driving force) in a mixed vapour condenser a condensation curve (temperature vs. enthalpy diagram) must be calculated showing the change in vapour temperature versus heat transferred throughout the condenser, Figure 12.48. The temperature profile will depend on the liquid-flow pattern in the condenser. There are two limiting conditions of condensate-vapour flow ... 

Fig. 4.21 Reduction of the heat flow rate in the condensation of methanol/water, a relative heat flux q/qo as a function of the temperature 4 -IL b boiling diagram...

A vapor to liquid change is condensation and it releases heat. However as shown in the diagram, the temperature of the system does not change. Therefore the released heat must have left system to the surroundings. Since heat flows from hot to cold, the temperature of the surroundings ( 7surr) must be low er than the temperature of the system (Tsys), and since... 

Therefore, approximate coefficients are used in industrial design, see Table 7.4-1. In any case it is recommended to draw diagrams in which both the temperature of the product and the temperature of the heating or cooling agent are plotted against the heat flow Q. In Fig. 7.4-4 this is shown for a heat exchanger and a condenser. 

Distillation column with top vapour recompression heat pump The flow diagram of the top vapour recompression scheme is shown in Fig. 2. The top column outlet stream is compressed with compressor to raise its temperature and promoting its energy content to be more usable. When the top column pressure is 21.6 bar, the temperature is increased from 81 to 139.9 C and also the pressure is increased from 21.6 to 52.6 bar. The compressor polytropic efficiency was assumed to be 70%. After the compressor, the heat exchanger allows transfer of the energy of this stream to boil up the bottom column outlet stream. With the same top column pressure and reflux ratio as before, the compressor outlet stream is condensed and cooled to 109.2 C, while the bottom column outlet stream is partially boiled. 

Bulk Recovery-Clous Process. The classic Claus process is the most common method of producing sulfur. Figure 2-8 is a simplified flow diagram of a typical Claus plant for a feed acid gas with greater than 50% H2S. The first thermal oxidation reaction is fast and takes place in a high-temperature (2,300-2,500°F) furnace-type reactor. The second reaction is relatively slow and requires several stages of catalytic reactors (400-500°F). The gas is cooled to condense and remove sulfur and is then reheated between reactors. The heat liberated by the reactions is used to make medium-pressure steam in the boiler and low-pressure steam in the sulfur condensers. 

A schematic flow diagram of the unit is shown in Figure 3-33. A solution of 48 wt% potassium hydroxide is added to the contaminated diethanolamine before it enters the top of a packed tower where it is contacted with superheated steam rising from the reboiler. Essentially all of the amine and water is vaporized, and the product is withdrawn at a point below the packed section into a condenser, which is held at a slightly lower pressure than that prevailing in the reboiler. A steam jet is used to maintain the required pressure. The salts drop into the reboiler and melt at 420 to 440°F, and any residual diethanolamine is flashed off. The temperature of the diethanolamine-water vapor withdrawn is 300 to 375°F. The temperatures in the column and reboiler are sufficient to vaporize practically all the amine without decomposition. Heat is supplied by circulating oil at 600°F through the reboiler tubes. Recovery of 90% of reusable diethanolamine is claimed. 

Figure 3.21 represents the process flow diagram of the rigorous model built by Aspen HYSYS. The model includes makeup gas streams and one column model to represent the VDU. In addition, we also add a heat flow to the feed stage to ensure that the flash zone temperature matches the plant measurement (Figure 3.22). The specifications of rigorous VDU model are similar to ADU model circulation rate and temperature change of each pumparound stream, flow rates of all liquid products except for one, top temperature (condenser temperature for ADU), and overflash rate/flash zone temperature [1]. By using the results of the simplified model first, we are able to apply these specifications to converge the VDU model with little effort...

Fig. 3A Block diagram of temperature-jump apparatus. The condenser is charged to 30-50 kilovolts and then discharged via a spark gap through the metal electrodes of the cell. This heats up a small portion of the solution some 3-10 degrees. This portion is monitored spectrally in the same manner as with the flow apparatus. An apparatus based on this arrangement was first manufactured by Messanlagen Stu-diengesellschaft, Gottingen, Germany.

In tank 25 the products of hydrolytic condensation are distilled from toluene. Cooler 26 is filled with water, and the tank jacket is filled with water vapour. The contents of the tank are heated to 80-90 °C and held at this temperature for 1 hour. The separated water and the intermediate layer are poured off into the intermediate container (not shown in the diagram) then toluene is distilled. First, the temperature in the tank at atmospheric pressure reaches 130 °C then, the tank is cooled to 70-90 °C and a residual pressure of 0.04-0.06 MPa is created in the system. Further distillation is conducted in the tank to 150 °C. The toluene vapours condensed in cooler 26 are collected in receptacle 27 and sent by compressed nitrogen flow (0.07 MPa) into flusher 28 as they accumulate. The flusher is filled with water, and the mixture is agitated for 10 minutes after that the agitator is switched off and the mixture is settled for 2 hours. The bottom layer, aqueous-alcoholic solution, is poured into neutraliser 13, and the top layer, washed toluene, is sampled for moisture content. If moisture content does not exceed 0.06%, toluene is poured into receptacle 30, sent to azeotropic drying (until the moisture content does not exceed 0.02%) and re-used in reactive mixtures. 

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