Methanol superheated vapor

In the process (Figs. 1 and 2), fresh and recycle methanol are vaporized, superheated, and passed into the methanol-air mixer. Atmospheric air is purified, compressed, and preheated to 54°C in a finned heat exchanger. 

A two-step methanolysis-hydrolysis process37 has been developed which involves reaction of PET with superheated methanol vapors at 240-260°C and atmospheric pressure to produce dimethyl terephthalate, monomethyl terephthalate, ethylene glycol, and oligomeric products in the first step. The methanolysis products are fractionally distilled and the remaining residue (oligomers) is subjected to hydrolysis after being fed into the hydrolysis reactor operating at a temperature of ca. 270°C. The TPA precipitates from the aqueous phase while impurities are left behind in the mother liquor. Methanolysis-hydrolysis leads to decreases in the time required for the depolymerization process compared to neutral hydrolysis for example, a neutral hydrolysis process that requires 45 min to produce the monomers is reduced... 

As the control valves to the various MTG reactors are adjusted, pressure waves may be transmitted to the methanol exchangers. If one exchanger is used for preheating, vaporizing and superheating the methanol feed, the pressure waves may cause the area used for vaporization to fluctuate thereby leading to potential instability in the vaporization rate. 

Figure 5.2. A schematic flow diagram of a bench scale reactor, based on the superheated methanol vapor bubble method.

To further decrease the cost required for production of BDF, Yamazaki et al. proposed a superheated methanol vapor bubble method (2007). 

Figure 5.2 shows a schematic flow diagram of a reactor based on the supercritical methanol vapor bubble method. In the reactor, superheated methanol vapor is blown into oil continuously, and reacted with triglyceride to form FAME. The formed FAME flows out from the reactor with unreacted methanol vapor and is collected by a condenser. No catalyst is used in this method. 

Reaction with the superheated methanol vapor bubble method can be conducted under atmospheric pressure conditions. Therefore, both initial and running costs for the process can be reduced, and applicability of the superheated methanol vapor bubble method might be high. 

A pilot scale reactor which can produce about 40 L of fatty acid methyl ester in a day by use of superheated methanol vapor bubble method has been constructed (Fig. 5.4). The feasibility of the process will be demonstrated by using the pilot scale reactor. 

Description Anhydrous liquid ammonia, recycled amines and methanol are continuously vaporized (1), superheated (3) and fed to a catalyst-packed converter (2). The converter utilizing a high-activity, low-byproduct amination catalyst simultaneously produces MMA, DMA and TMA. Product ratios can be varied to maximize MMA, DMA, or TMA production. The correct selection of the N/C ratio and recycling of amines produces the desired product mix. Most of the exothermic reaction heat is recovered in feed preheating (3). 

Description Anhydrous liquid ammonia, recycled amines and methanol are continuously vaporized (1), superheated (3) and fed to a catalyst-packed converter (2). The converter utilizing a high activity, low byproduct amination catalyst simultaneously produces MMA,... 

Henkel has developed a continuous countercurrent esterification using a doubleplate reaction column. The technology is based on the principle of an esterification reaction with the simultaneous absorption of the superheated methanol vapor and desorption of the methanol-water mixture (15). 

Feed to the reactor is a simulated crude methanol stream consisting of a mixture of 83% methanol and 17% water. The reactor accommodates a dense fluid catalyst bed measuring 2 ft in diameter by 40 ft in hei t. The feed can either be injected as a liquid or vaporized and superheated before entering the reactor. The feed passes throu the bed, where it is converted quantitatively... 

In the synthesis step, the pressure is operated at 70 to 5(K) psig. Methanol, ammonia, and the recycled amines, which are in excess of market demand, are vaporized in a vaporizer. The mixture then is superheated to about 300 to 400 C before entering the reactor. The feed temperature, which is controlled to keep the MeOH conversion close to completion, is increased as the throughput in the reactor increases and as the catalyst deactivates during its life. The reactor typically is an adiabatic fixed-bed catalytic reactor where the residence time is 10 to 40 seconds. The heat of reaction is recovered by preheating the feed mixture in a heal exchanger. 

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