Manufacturing processes continuous type

Substrate. The substrate serves as a mechanical support for the sintered stmcture and as a current collector for the electrochemical reactions which occur throughout the porous sintered portion of the plate. It also provides mechanical strength and continuity during the manufacturing processes. Two types of substrate are typically used (1) perforated nickel-plated steel or pure nickel strip in continuous lengths, and (2) woven screens of nickel or nickel-clad steel wire. A common perforated type may be 0.1 mm thick with 2-mm holes and a void area of about 40%. A typical screen may use 0.18-mm-diameter wire with 1.0-mm openings. 

The unique properhes of zeolite materials combined with the conhnuous separahon properhes of membranes make zeolite membranes very attrachve for a wide range of separahon and catalysis applications. Zeolite membranes, however, have poor processability, poor mechanical stability and are much more expensive than the commercial polymer membranes with current state-of-the-art membrane manufacturing process. So far, the only large-scale commercial zeolite membrane is the A-type zeolite membrane and it has been used for dehydrahon of alcohols [22]. Further advancement in making thinner zeolite membranes and continuous improvement in membrane produchon techniques and reproducibility will make zeolite membranes more successful in commercial applicahons. 

An objective metric is needed to gauge the level of manufacturing process understandings and control achieved—process capability can be this metric. During development studies, process capability analysis can be performed in terms of probability distribution (type of distribution, mean and variability) without regard to specifications (14) such analysis can provide useful supporting information on variability and may provide additional support for proposed regulatory acceptance criteria. Inherent variability in clinical materials can then be a benchmark and a basis for continuous improvement. 

In the gas black process (Fig. 55), the feed stock is partially vaporized. The residual oil is continuously withdrawn. The oil vapor is transported to the production apparatus by a combustible carrier gas (e.g., hydrogen, coke oven gas, or methane). Air may be added to the oil-gas mixture for the manufacture of very small particle size carbon black. Although this process is not as flexible as the furnace black process, various types of gas black can be made by varying the relative amounts of carrier gas, oil, and air. The carbon black properties are also dependent on the type of burners used. 

Nitrobenzene (Aniline). The U.S. nitrobenzene production was about 2 billion lb in 1999. Two types of manufacturing processes were used the direct nitration and the adiabatic nitration process. In the direct nitration system, benzene is mixed with a mixture of nitric/ sulfuric acid. The reaction can be carried out in either a batch or a continuous system. Those reactors require a cooling system to keep it at constant temperature. It also requires a separate system for sulfuric acid reconcentration. In the adiabatic process, water is flashed off under vacuum before the sulfuric acid/nitrobenzene separation. The advantage of the adiabatic process is to eliminate a separated sulfuric acid reconcentration unit. This also will provide a better heat integration. Recently, the disposal of nitrophenols has become a major issue for aniline manufacture. Small amounts of nitrophenols are always made during the benzene... 

Because of the heterogeneous nature of the mixture, and presence of contaminants, the articles produced should have large cross-sections, so that small imperfections do not hinder the mechanical performance of the products. Products can be manufactured by continuous extrusion, compression molding, or by Klobbie-based intrusion processes. Intrusion process is a cross between conventional injection molding and extrusion. In this, the extruder first works and softens the thermoplastic mixture, which is poured into one of the molds without using screen packs or nozzles. Today s recycling equipments are capable of processing most types of mixed thermoplastic material, even with up to 30 to 40 percent contamination as unmelted polymers or nonpolymer materials such... 

Types of Process Equipment. Nitrations, as technical industrial processes, have evolved from batch-type operations using stoneware vessels and hand operations to automatically controlled continuous-type processes carried out in gleaming stainless-steel vessels. The high heats of reaction and dilution involved in nitration, originally absorbed by placing the stoneware vessels in a water bath, are now taken up by coils or jackets cooled by refrigerated brine. Controls have evolved from none at all to completely automatic,systems which may be so elaborate as to permit operation from remote locations. The idea of remote control has always appealed to the designer of equipment for the manufacture of hazardous, explosive compounds which often are the result of nitration processes. 

---