US 5,657,555 AGranted

Process and hot-air dryer for dying coated surfaces

AssigneeABB Flakt AB

InventorsDragoslav Milojevic, Manfred Losch

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Abstract

In a process for drying coated surfaces in a hot-air dryer, part of the hot air in the dryer is continuously circulated therein as a secondary air stream which is mixed with a primary air stream heated to above the drying temperature (T.sub.max). This reduces the quantity of hot air to be fed into the dryer and thus the material requirements are reduced and the heating time shortened. A hot-dryer for implementing the process has, in the hot-air chambers (7,8) arranged symmetrically on either side in the interior (6) of the dryer, a separating wall (22) dividing an internal chamber (7) and an outer chamber (8) which has fun intake aperture (9) at its lower end for secondary air. At the lower end of the inner chamber (7), the primary air is fed in at a higher flow rate and mixed with the secondary air taken in through the aperture (9).

A hot-air dryer for carrying out a process for drying coated surfaces in a dryer tunnel space of a hot-air dryer in which hot air with a drying temperature is introduced into the dryer, circulated therethrough and, after appropriate heat transfer, removed again, part of the hot air in the dryer being continuously circulated therein as a secondary air stream (18) and a primary air stream (17) heated above the maximum allowing drying temperature (T.sub.max) being mixed with this secondary air stream (18),

wherein the primary air stream suctions and conveys the secondary air stream with the injection as well as mixing of the primary air and the secondary air ensuing in a chamber separated from the dryer tunnel space,
said dryer including
two tunnel-like zones successively arranged in the direction of passage of the coated object (1), a radiation dryer (radiation zone) and a circulation dryer (convection zone), which respectively have an outer housing (4) and inner walls (23) which form a central interior (6) and two lateral, substantially vertically aligned hot-air chambers arranged symmetrically with respect to the interior (6),
a separation wall (22) respectively subdividing each of the hot-air chambers into an inner and outer chamber (7 and 8), which walls each have an opening (9) at their lower end which connects the two chambers (7, 8),
a hot air stream flowing in the outer chamber (8) from above to below and in the inner chamber (7) from below to above,
wherein an apparatus (10, 25) is arranged at the lower end of the inner chamber (7) for introducing with an increased flow velocity a primary air stream (17) heated to above the maximum allowable drying temperature (T.sub.max),
the connecting opening in the partition wall (22) is formed as a suction opening (9) through which at least part of the hot air stream flowing downwards in the outer chamber (8) is suctioned as a secondary air stream (18) and mixed with the primary air stream (17) (forming an integrated air circulation).

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Facts

Application

08/582,989Filed 20 Mar 1996

Priority

DE 43 24 488.221 Jul 1993

Granted

19 Aug 1997

Term ends

Not estimatedThe source records don’t support an estimate.

Classification5 codes

F26B 3/283
By radiation, e.g. from the sun: in combination with convection
F26B 21/20
Arrangements for supplying or controlling air or other gases for drying solid materials or objects: circulating air or gases in closed cycles,…
F26B 23/10
Heating arrangements: using tubes or passages containing heated fluids , e.g. acting as radiative elements; Closed-loop systems
F26B 2210/12
Drying processes and machines for solid objects characterised by the specific requirements of the drying goods: vehicle bodies, e.g. after being…

Abstract

Claims16