Batch preheating

R.W. Breault, A. Litka, A.W. McClaine, R.P. Chamberland, D.T. McNeil, T. WUsoncroft, "An Integrated Cullet/Batch Preheater System for Oxygen-Fuel Fired Glass Furnaces," American Flame Research Committee, September 30-October 2, (1996), Baltimore, Maryland. 

Figure 2 Energy balance of modem energy efficient container glass iiiraace (end-port regenerative, natural gas - air fired, 84% cullet), no batch preheater.

Today, a few manufacturers of such batch preheating systems are developing adapted configurations to enable the preheating of batch with low cullet levels, down to 10 % for instance, without clogging problems [3,4,7,17,18]. Figure shows a sketch of the newly developed Zippe preheater (18],... 

Fiigure 5 Sketches of a Zippe batch preheater (left) [18] and SORC batch preheater (right) [17]... 

Especially, in case of the final development and proof of the new generation batch preheaters that allow preheating of cullet-lean batches, without contaminating the batch by abrasion of the inner steel construction, application of batch preheating becomes possible for non-container glass furnaces as well. 

M. Lindig New developments in batch preheating. NCNG Workshop Energy Recovery from Waste Heat in the Glass Industry. 6. October 2011, Eindhoven. 

Table I container glass furnace without and with batch preheating. CO2 reduction with preheating...

With batch preheat operation it might also be recommended to reduce application of electric boosting as much as possible. E-boost application might reduce CCb-emission on short term relevant to the facility only. Electric power generation produces about O I4m3/kWh (0,421 kg/kWh) CO2. A comparative analysis of the CO2- Emission for different operation conditions is given in the following table... 

Table 2 comparative analysis influence of batch preheat and boosting on CO2- emission... 

Batch Process. In the batch process (Fig. 5), the feedstock is preheated in a tube furnace or heater placed between the feedstock storage and the blowing vessel. The air supply is provided by a variety of blowers or compressors and a vertical-tower vessel is preferable for air-blowing. Knockout dmms, water scmbbers, incinerators, furnaces, and catalytic burning units have been used for fume disposal (32). Steam is used for safety and to ensure positive fume flow to the incinerator. 

Both continuous and batch methods may be used in methanolysis. The batch mediod requires an autoclave, crystallizer, and centrifuge and a system for the melting and distillation of the DMT obtained. In the two-stage Hoechst continuous process, waste PET is melted and fed to a reactor. Preheated methanol is added to the autoclave, which is equipped with a mixer. The conversion reaches 70-90% in the first reactor, after which the reaction stream is introduced into a second autoclave at a lower temperature near the bottom, where it rises slowly and die higher density impurities settle at the bottom. The reaction stream leaves the second autoclave and its pressure is reduced to 0.3 MPa. On further reduction of the pressure and cooling, DMT precipitates and is subsequently purified.12... 

Section 1.5 described one basic problem of scaling batch reactors namely, it is impossible to maintain a constant mixing time if the scaleup ratio is large. However, this is a problem for fed-batch reactors and does not pose a limitation if the reactants are premixed. A single-phase, isothermal (or adiabatic) reaction in batch can be scaled indefinitely if the reactants are premixed and preheated before being charged. The restriction to single-phase systems avoids mass... 

XANES to ensure the quality of the synthates. Three batches of ferrihydrite were synthesized and precipitates were washed 5-6 times to ensure a chloride-free synthate. Ferrihydrite precipitates were redispersed in 200 mL of double deionized (DDI) water at (1) room temperature (25°C), as well as preheated in water baths to temperatures of (2) 50°C and (3) 75°C. For all of these slurries, pH was kept constant at 10 using 1M KOH. 40 mL samples were pipetted from each reaction vessel after 0, 1,2, 3, and 7 days. Slurries were centrifuged, washed three times with DDI water and air dried for analyses (BET, XRD, and XANES). BET analyses were used to evaluate the decrease in surface areas with increasing crystallinity, and XRD and XANES were used to detail the structural and speciation changes in iron. 

In the example above, it appears that all the bases are covered and they may well be, depending upon the analyst s needs. It is easy to overlook valuable functions that we may expect without further thought. In this case, we have not specified that media should be preheated while a previous method is running. The sequence of events has not been well characterized. Here, it can cause a delay in run time for the batch is media is not heated prior to completion of the prior batch. 

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