Hydrogen Process Optimization

The control and optimization of high-pressure and low-temperature processes require the same control strategies as any other industrial process. The difference is only in the selection of the construction materials, which are used in the sensors and control valves. In fact, process control tends to be less sophisticated in hydrogen applications. 

A good example is the control of the Space Shuttle engines, where each of the three engines generates 200,000 kgf (400,000 lbf) lifting force and each weighs 3,200 kg (7,000 lb). These engines can operate at extreme temperatures as the LH2 fuel is at -253°C (-423°F), and when burned, its combustion temperature reaches 3,300°C (6,000°F). Yet, the controls used are not that sophisticated at all. 

On-off control is used to keep the vapor pressure within limits in both the fuel (hydrogen) and oxidant (02) tanks. The LH2 storage tank vapor space, for example, is held between 32 and 34 psig. Below 32 psig a GH2 supply valve is opened to the tank at 33 psig this valve closes, and at 35 psig a relief valve is opened. The same type of on-off control is applied to keep the 02 tank pressure between 20 and 22 psig. Similarly, to control the propellant flows, the 17 in. control valves are pneumatically operated. 

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Rapid Optimization of Hydrogenation Process Variables by Combining Experimental... 

As Figure 14.5 shows, the enantio-differentiating (e.d.) hydrogenation consists of three processes (1) catalyst preparation, (2) chiral modification, and (3) hydrogenation reaction. These processes imply preparation variables for activated nickel, as a base catalyst for modified Ni, modification variables for the activated catalyst, and reaction variables of the hydrogenation processes, respectively. All these factors should be optimized for each type of substrate. 

Hawkes, F.R., Dinsdale, R.M., Hawkes, D.L., Huss, I. 2002. Sustainable fermentative hydrogen production challenges for process optimization. Int J Hydrogen Energy 27 1339-1347. 

Mukhopadhyay, S., Rothenberg, G., Wiener, H. and Sasson, Y. (1999) Palladium-catalyzed aryl-aryl coupling in water using molecular hydrogen kinetics and process optimization of a solid-liquid-gas system. Tetrahedron, 55, 14, 763. 

Tetralone has been reduced to (7 )-1-tetralol with 166 at the 200-L scale (Scheme 12.65). The hydrogen source was /-PrOH. Initially, the maximum concentration to achieve high conversion was 0.05m in a closed system, but the ee decreased near the latter conversions. The key discovery in process optimization was removal of acetone by-product during the reaction. The catalyst is not stable at higher than 40°C however, the reaction can be performed under a slight vacuum (10-50 mbar) to remove acetone. Fresh IPA is added to the reaction to maintain constant volume. Under these conditions coupled with efficient agitation, substrate concentrations of 0.5m are achieved with complete conversions (TOF = 500-2500 Ir1) and reproducible enantioselectivity.212... 

Compressor controls play an important role in the optimization of renewable energy processes. Their applications are discussed in detail in connection with hydrogen processing (see Chapter 1, Section 1.5.5), geothermal power plants (see Section 1.3.4), and heat pumps (see Section 2.4). 

At the outset of the project, we established as a yardstick for economic comparison, an entirely new unit based on the old hydrogenation process technology. No attempt was made to improve it, either in the light of experience or knowledge gained from the study described in this paper. Dubbed irreverently the "Rubber Stamp", the old process, while chemically efficient, was characterized by significantly higher product costs than was the new optimized process. 

This statement applies without any restriction to coal liquefaction as well. Hence, for hydrogenation process engineering the optimization of the reaction conditions has precedence over the raw material properties. 

The 2" phase (2006-2009) R D activities undertake a SI process optimization and the performance tests of various chemical reactors selected for the SI cycle. The 2" phase research covers a dynamic code development for the SI process, a construction of a lab. scale( l 000 NL/h) SI process, and integrated operations of the process at prototypical pressures. On the other hand, conceptual and basic designs of a pilot scale( 100 Nm /li) SI process and its equipment will also be carried out according to the optimized process established from the theoretical evaluation using a commercial-base computer code and the experiences of the lab. scale construction and operations. Preliminary performance tests of the equipment, mechanical devices, and accessories for the pilot scale SI process should be carried out to obtain the design basis. Not only the several catalysts based on non-noble metals required for section II in the SI cycle but also a membrane for the separation of the hydrogen required for section III will be developed during the 2" phase research period. 

M. M. Ermilova, N.V. Orekhova, and V.M. Gryaznov, in R. Bredesen, Ed., "Optimization of the Selective Hydrogenation Process by Membrane Catalysts", Proc. Fourth Workshop Optimisation of Catalytic Membrane Reactors Systems, Oslo, Norway, May, 1997, 187. 

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