Methanol Reactors

It is of interest to assess the process potential of methanol production by a direct partial oxidation of methane. This way the steam reformer and the shift reactor can be saved, and the catalytic methanol reactor can be replaced by a noncatalytic partial oxidation reactor. It is estimated that direct partial oxidation is competitive if a conversion of methane of at least 5.5% can be obtained with a methanol selectivity of at least 80%. 

Figure 17.24. Types of reactors for synthetic fuels [Meyers (Ed.), Handbook of Synfuels Technology, McGraw-Hill, New York, 1984], (a) ICI methanol reactor, showing internal distributors. C, D and E are cold shot nozzles, F = catalyst dropout, L = thermocouple, and O = catalyst input, (b) ICI methanol reactor with internal heat exchange and cold shots, (c) Fixed bed reactor for gasoline from coal synthesis gas dimensions 10 x 42 ft, 2000 2-in. dia tubes packed with promoted iron catalyst, production rate 5 tons/day per reactor, (d) Synthol fluidized bed continuous reactor system for gasoline from coal synthesis gas.

C. W. Janes, "Increasing Gas Turbine Efficiency Through the Use of a Waste Heat Methanol Reactor", IECEC 799423 (1979). 

Anonymous, Methanol Reactors-Converter Options for Methanol Synthesis , Nitrogen 1994, 210, 36-44... 

Figure 5.3.3 A simplified schematic of a methanol synthesis plant (A) gasifier, (B) compressor, (C) methanol reactor, (D) flash drum, (E) light-ends column, and (F) methanol column.

Important progress was also made in chemical engineering, such as use of rotary compressors in ammonia synthesis or ICI s fermentation reactors in Billingham to produce the Pruteen protein from methanol reactors, having no mobile parts. 

The pressurized gas then is led to the methanol reactor. Two different catalyst systems may be used (l) a zinc-chromium catalyst requiring gas pressures of 2000-4000 psi or (2) a copper catalyst system at 1000-2000 psi. About 95 percent of the gas is converted to methanol by this exothermic reaction ... 

The "preconverted" gas is routed to the shell side of the gas-cooled methanol reactor, which is filled with catalyst. The final conversion to methanol is achieved at reduced temperatures along... 

The synthesis loop consists of a recycle compressor, feed/effluent exchanger, methanol reactor, final cooler and crude methanol separator. Uhde s methanol reactor is an isothermal tubular reactor with a copper catalyst contained in vertical tubes and boiling water on the shell side. The heat of methanol reaction is removed by partial evaporation of the boiler feedwater, thus generating 1-1.4 metric tons of MP steam per metric ton of methanol. Advantages of this reactor type are low byproduct formation due to almost isothermal reaction conditions, high level heat of reaction recovery, and easy temperature control by... 

Crude methanol that is condensed downstream of the methanol reactor is separated from unreacted gas in the separator and routed via an expansion drum to the crude methanol distillation. Water and small amount of byproducts formed in the synthesis and contained in the crude methanol are removed by an energy-saving three-column distillation system. 

The preconverted gas is routed to the shell side of the gas-cooled methanol reactor, which is filled with catalyst. The final conversion to methanol is achieved at reduced temperatures along the optimum reaction route. The reactor outlet gas is cooled to about 40°C to separate methanol and water from the gases by preheating BFW and recycle gas. Condensed raw methanol is separated from the unreacted gas and routed to the distillation unit. The major portion of the gas is recycled back to the synthesis reactors to achieve a high overall conversion. The excellent performance of the Lurgi combined converter (LCC) methanol synthesis reduces the recycle ratio to about 2. A small portion of the recycle gas is withdrawn as purge gas to lessen inerts accumulation in the loop. 

Zardi. U.," Review these devdopmeats m ammonia and methanol reactors". Hydrocarbon Processing, 61 (8) 129-133 (1982). 

Sulphur is detrimental to the sjmthesis and trace amounts of sulphur are removed using zine oxide prior to synthesis. After the production of synthesis gas, the methanol sjmthesis requires compression to about lOObar. The methanol synthesis loop con rises a reactor, a separator and recompression of the reeyele gas. A purge gas can be used to produce power supplemented by steam raised in the methanol reactor and the coal gasifier. The crude methanol produced can be upgraded to chemical grade product by distillation. The intermediate methanol is passed into storage. The reaction stoichiometry is ... 

P2-IS5 Review the reactor volumes calculated in each of the example problems in this chapter. Using the methanol reactor described in Chem. Eng. Prog., 79(7), 64 (1983) as a basis of comparison, classify each of the reactor sizes and flow rates in the example problems as industrial, pilot plant, or laboratory scale. 

The catalyst deactivation studies described here were carried out in 300 cm.. gas-sparged, stirred autoclaves and in a nominal 10 ton (CH30H)/day pilot-plant, bubble-column reactor. The details of the design and operation of these reactor systems have been reported elsewhere [refs. 4,5]. AH of the present studies were carried out with a feed gas that is referred to as "CO-Rich Gas , with a molar composition of H2 35%, CO-51 %, C02-13% and N2 1%- Its stoichiometric ratio, defined as H2/(CO+1.5002), is 0.5. A typical stoichiometric ratio for the feed to a conventional methanol reactor Is about 2.6, well on the H2-rich side of 2.0, the ratio tor exact stoichiometric equivalence. The feed concentrations of known poisons such as hydrogen sulfide, carbonyl sulfide, chlorine compounds, iron carbonyl and nickel carbonyl were below the limits of detection, 50 ppb, 50 ppb, 10 ppb, 50 ppb and 50 ppb, respectively. 

In a commercial methanol plant, it is economicafly desirable to maintain a constant methanol production rate as the catalyst ages. With conventional, fixed-bed reactors, the feed temperature is raised gradually with time to compensate for catalyst deactivation. The mathematical model of catalyst deactivation developed in the previous section was used to test the feasibility of this strategy for a single slurry methanol reactor operating with CO-Rich Gas. The reactor was assumed to be completely backmixed, which simplifies the mathematics of the analysis [ref. 7]. 

Continuous catalyst addition and withdrawal Is probably the most practicaf means to maintain constant production in a slurry methanol reactor. It gives the plant operator the flexibility to trade off catalyst replacement cost against methanol production rate, and It avoids the total reactor shutdown that is required to change Out a deactivated fixed-bed catalyst. 

Ten percent excess steam, based on reaction (a), is fed to the reformer, and conversion of methane is 100%, with a 90% yield of CO2. Conversion in the methanol reactor is 55% on one pass through the reactor. 

A stoichiometric quantity of oxygen is fed to the CO converter, and the CO is completely converted to CO2. Additional makeup CO2 is then introduced to establish a 3-to-l ratio of H2 to CO2 in the feed stream to the methanol reactor. 

The methanol reactor effluent is cooled to condense all the methanol and water, with the noncondensible gases recycled to the methanol reactor feed. The H2/CO2 ratio in the recycle stream is also 3 to 1. 

The configuration of a 7000 MTPD DME plant is based on the combination of methanol synthesis and methanol dehydration. Attractive features of this process include lesser total investment cost and lesser oxygen consumption when compared with the methanol/DME coproduction route or direct DME synthesis route. Also, carbon dioxide is not produced in the DME synthesis step of this process. As shown in Fig. 6, this process utilizes a steam reformer, TEC s TAF-X reactor, oxygen reformer, TEC s MRF-Z methanol reactor, and TEC s DME reactor. 

Consider the following mixture that is coming out of a methanol reactor CO, 100 kmol/h H2, 200 kmol/h methanol, 100 kmol/h. The gas is at 100 atm and 300°C. Compute the specific volume using (1) ideal gas law (2) Redlich-Kwong equation of state and (3) Redlich-Kwong-Soave equation of state. The acentric factors for the RK-Soave method are CO, 0.049 H2, -0.22 methanol, 0.559. Where did you get the other data you needed How do the three answers compare Is the gas ideal or not Comment. 

Fig. 2 shows the I.C.I. warm-shot methanol synthesis loop. The adiabatic methanol reactor has multiple catalyst beds which cure quenched with warm reactant gas that control the methanol converter s temperature profile and methanol outlet concentration as portrayed in Fig. 3.. In this adiabatic quench redctor methanol loop scheme, the main features are ...

Figure 3.9 shows the proposed flowscheme. The natural gas, sourced from the pipeline, is desulfurized, preheated and led into a reactor where it is reformed to synthesis gas. The temperature controlled reactor continuously combines reaction and heat exchange, to maximize the utilization of the energy contained in the waste stream (discussed later). The synthesis gas is compressed and led into the methanol reactor. The methanol reactor is preferably of the temperature controlled type, again to maximize the heat transfer and maximize the intensity of the catalytic operation. The partially converted stream is subsequently flashed to remove methanol and water. Rather than recycling and recompressing the stream, it is expanded in a gas turbine, producing power. 

Baddour et al. [26] in their simulation of the TVA ammonia-synthesis converter, already discussed in Sec. 11.5.e, found that in steady-state operation the temperature difference between the gas and the solid at the top, where the rate of reaction is a maximum, amounts to only 2.3°C and decreases as the gas proceeds down the reactor to a value of 0.4°C at the outlet. In the methanol reactor simulated in Sec. 11.9.b the difference between gas and solid temperature is of the order of 1 C. This may not be so with highly exothermic and fast reactions involving a component of the catalyst as encountered in the reoxidation of Fe and Ni catalysts used in ammonia synthesis and steam reforming plants or involving material deposited on the catalyst, coke for example. 

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