Heat exchanger tube pass

The ventilation capacity required for drying amounts to 0.4-0.5 m3/hen/h at a backpressure of 500-1000 Pa in the heat exchanger tubes. The pressure is determined from the volume of air, the length and cross-section of the perforated ducts. For good drying, the pressure at the end of the perforated duct must be at least 300-350 Pa. This is the lowest pressure at which the air can be blown out of the holes at a speed of ca 20/m/sec., so that it can be distributed over the manure on the belt at a speed of 0.5-2.0 m/sec. 

Column with random packing (see Table 2-27) or tower with random packed tubes (heat exchange possible to a cooling agent on the shell side). Specific surface 50-300 mVm diameter up to 2.5 m vapor load factor 1-2.5 Pa trickle density 2-100 m / (m h) specific pressure drop 20-120 mm water gauge gas and liquid phase are both continous. 

A major technical hurdle to overcome in making an all-plastic heat exchanger is welding tubes to the base plates of tanks. A heat exchanger that must remove a large quantity of heat quickly requires a large number of tubes, usually closely packed. Various techniques to achieve this have been investigated. The materials for tubes and tank plates were all polyamides various combinations of PA 66, PA 612 and PPA were studied. Data on successful laser welds are presented. 

X-ray and aluminium MAS NMR measurements were carried out on samples rehydrated in a desiccator over an aqueous NH,C1 solution. A portion of the zeolites synthesized with organic templates was heated for 5 h at 600 °C to remove organic compounds. The Na /H ion exchange was carried out at room temperature with an aqueous solution of 0.5 N HC1. The preparation of 1H MAS NMR samples was performed under shallow bed activation conditions in a glass tube of 5.5 mm inner diameter and 10 mm height of the zeolite layer. The temperature was increased at a rate of 10 K/hr. After maintaining the samples at the final activation temperature of 400 °C under a pressure below 10 L Pa for 24 hrs., they were cooled and sealed. 

External short tube, vertical exchanger, natural circulation OK for foaming but not for fouling, crystal formation, or suspended solids. Viscosities <20 mPa-s. Relative to agitated film retention time of 16 1 and volume 10 1. Overall heat transfer coefficient 1 to 1.5 kW/m °C. HDHI = 10 to 10 Pa s. Area 3 to 1000... 

---