Thermodynamically regulated method and thermodynamically regulated drying system for drying goods to be dried

Abstract

The invention relates to a drying system (T) according to FIG. 1 for drying goods to be dried (LTG), comprisinga drying tunnel (TT), a line (LAG) for exhaust gas (AG) containing (VOC) out of the drying tunnel (TT), a controlled fan (GBL) for further transporting the exhaust gas (AG) to a heat exchanger (WT), a heat exchanger (WT) for heating the exhaust gas (AG) using the clean gas (RG), an exhaust gas line (LAG) downstream of the heat exchanger (WT) for further transporting the exhaust gas (AGWT) to a burner (BR) in a combustion chamber (BK) of a thermal post-combustion system (TNV), a cold bypass (BP) which bypasses the heat exchanger (WT) and which can be regulated using an electronically controlled controller (R), a fuel line (LEG) for a fuel (EG) to the burner (BER), a clean gas line (LRG) for transporting the clean gas (RG) out of the combustion chamber (BK) to the heat exchanger (WT) in order to cool the exhaust gas (AG), a clean gas line (LRG) for conducting the clean gas (RG) from the heat exchanger (WT) to the heat consumers (WA), a heater (HZTT) for heating the drying zone (TT) by means of the heat consumers (WA), and a clean gas line (LRG) for conducting the clean gas (RGD) to a stack (K). The invention also relates to a drying method and a method for a thermodynamic regulation (TDR).

Claims

1. A thermodynamically controllable drying plant for drying of drying goods, comprising: at least one drying tunnel through which drying goods can be conveyed in a conveying direction; at least one heat exchanger; at least one blower controlled by a frequency converter for controlled transport of exhaust gas from the at least one drying tunnel to the at least one heat exchanger; at least one exhaust gas pipe downstream of the at least one heat exchanger through which the exhaust gas is transportable in varying amounts to at least one burner in at least one combustion chamber of at least one thermal post-combustion facility, the at least one exhaust gas pipe containing volatile organic compounds out of the at least one drying tunnel; at least one cold bypass circumventing the at least one heat exchanger and connecting the at least one exhaust gas pipe upstream of the at least one heat exchanger with the at least one exhaust gas pipe downstream of the at least one heat exchanger, wherein the at least one cold bypass is controllable with at least one electronically regulated control station; at least one fuel pipe through which fuel is controllably transportable to the at the least one burner; at least one clean gas pipe through which clean gas is transportable from the at least one combustion chamber to the at least one heat exchanger, the clean gas having variable temperatures, wherein the exhaust gas is variably heated by the clean gas at the least one heat exchanger, wherein the at least one clean gas pipe transports variably cooled clean gas from the at least one heat exchanger to at least one heat consumer (WA), and wherein the at least one clean gas pipe transports the variably cooled clean gas to at least one chimney, where the variably cooled clean gas is releasable into atmosphere as clean gas exhaust; at least one heater by which the at least one drying zone is heatable by the at least one heat consumer; at least one thermodynamic control unit having an algorithm based on; Equation I: Control Equation for a measuring station downstream of the heat exchanger:
?.sub.TNV[W]+?.sub.AG[W]=?.sub.WA[W]+?.sub.RGD[W]; Equation II: Control Equation relative to a vantage point of the at least one thermal post-combustion facility:
?.sub.TNV[W]=?.sub.WA[W]+?.sub.RGD[W]??.sub.AG[W]; Equation III: control difference ? upstream of the control unit:
?={?.sub.WA[W]+?.sub.RGD[W]??.sub.AG[W]}??.sub.TNV[W]; with ?.sub.WA [W] ?.sub.RGD [W]??.sub.AG [W]=target value and ?.sub.TNV [W]=actual value, wherein the target value is defined as follows: (i) ?.sub.WA [W] as a heat reduction of the drying plant to be compensated, (ii) ?.sub.AG [W] as a recuperation of heat from the drying plant to be compensated/included, and (iii) ?.sub.RGD [W] as an energy content of the clean gas exhaust; Regulating Variable: a volume stream {dot over (V)} at normal or standard conditions (temperature=273.15 K, pressure=1013.25 mbar); and Equation IV: a combustion chamber temperature:
T.sub.BK=f({dot over (V)}.sub.variabel), wherein {dot over (V)}.sub.variabel=volume stream of the clean gas in the at least one clean gas pipe.

2. The thermodynamically controllable drying plant as claimed in claim 1, further comprising: at least one first measuring station for a temperature of the exhaust gas; at least one second measuring station for a volume stream of the exhaust gas in the at least one exhaust gas pipe; at least one first controllable actuator for the at least one blower; at least one third measuring station for a temperature of the exhaust gas in the exhaust gas pipe downstream of the at least one heat exchanger and upstream of the at least one combustion chamber; at least one pilot valve in the at least one cold bypass which is controlled by the at least one electronically regulated control station; at least one control valve in the at least one fuel pipe for controlling flow of the fuel; at least one second controllable actuator for the at least one control valve in the at least one fuel pipe; at least one fourth measuring station for a temperature of the clean gas in the at least one clean gas pipe downstream of the at least one heat exchanger; at least one fifth measuring station for a temperature of the clean gas in the at least one clean gas pipe downstream of the at least one heat consumer; at least one sixth measuring station for a temperature of the clean gas in the at least one clean gas pipe upstream from the at least one heat exchanger; and at least one seventh measuring station for a temperature in the at least one combustion chamber of the at least one post-combustion facility.

3. The thermodynamically controllable drying plant as claimed in claim 1, wherein the at least one heat consumer acts as the at least one heater for the at least one drying tunnel.

4. The thermodynamically controllable drying plant as claimed in claim 2, being controllable with at least one thermodynamic control station.

5. The thermodynamically controllable drying plant as claimed in claim 4, wherein the at least one thermodynamic control station comprises: at least one first input of the measured values of the temperature of the exhaust gas in the at least one exhaust gas pipe downstream of the at least one heat exchanger from the third measuring station; at least one second input of the measured values of the temperature of the exhaust gas from the first measuring station; at least one third input for the measured values of the combustion chamber temperature from the seventh measuring station; at least one fourth input for the measured values of the temperature from the fifth measuring station; at least one fifth input for the measured values of the volume stream of the clean gas in the at least one clean gas pipe from the second measuring station; at least one sixth input of target values of the temperature of the clean gas in the at least one clean gas pipe downstream of the at least one heat exchanger from the fourth measuring station; at least one first output of target values to the at least one second controllable actuator; at least one second output of target values to the at least one electronically regulated control station; and at least one third output of target values to the at least one first controllable actuator for the at least one blower.

6. The thermodynamically controlled drying plant as claimed in claim 1, wherein the at least one heat consumer is selected from the group consisting of waste heat boilers, recuperators, heat exchangers and gas pipes.

7. The thermodynamically controlled drying plant as claimed in claim 1, wherein the drying goods are formed plastic parts, which are dissolved and/or melted at their surface, glued composites of all kinds, the adhesive layers of which are not yet dried, and formed objects coated by spray coating, powder coating, curtain coating, electrodeposition coatings and doctor blade coating, and formed objects of all kind printed or painted by sieve printing, intaglio printing, offset printing, relief printing, and flexographic printing.

8. The thermodynamically controllable drying plant as claimed in claim 7, wherein the drying goods (LTG) are building parts for architectural purposes, such as window frames, grids, railings, doors, stairs, rod assemblies, tubes, and mobile buildings; building parts and chassis of means of locomotion such as automobiles, trucks, buses, building machines, motorcycles, mopeds, quads, scooters, pedal-scooters, hoover boards, skateboards, longboards, two-wheel wind runners, locomotives, train wagons, airplane parts, hulls; high-quality household appliances; heating elements; radiators and building parts for sanitary purposes.

9. A process for drying of drying goods in at least one thermodynamically controllable drying plant, wherein the drying goods are conveyed through at least one drying tunnel in a conveying direction and thereby dried, comprising: exhaust gases containing volatile organic compounds are sucked off through at least one exhaust gas pipe from the at least one drying tunnel; the exhaust gases are transported by at least one blower controlled by a frequency converter to at least one heat exchanger, whereby an amount of the sucked off exhaust gases is controlled; the exhaust gases are, at least temporarily, heated to variable exhaust gas temperatures in the at least one heat exchanger by clean gas in at least one clean gas pipe upstream of at least one thermal post-combustion chamber facility; the exhaust gases are transported through at least one cold bypass circumventing the at least one heat exchanger and connecting the at least one exhaust gas pipe upstream and downstream of the at least one heat exchanger, the at least one cold bypass being regulated by at least one pilot valve controlled by at least one control station, wherein the pilot valve remains temporarily open or closed or remains partially or completely open or closed during a complete drying process, wherein a temperature of exhaust gas is kept constant or is varied; the exhaust gases are transported through the at least one exhaust gas pipe from the at least one heat exchanger to at least one burner; the exhaust gases are mixed in varying amounts with fuel which is supplied by at least one fuel pipe; the exhaust gases are burned in the at least one burner in at least one combustion chamber of at least one thermal post-combustion facility in at least one flame at variable combustion chamber temperatures; the clean gas having variable temperatures is transported out of the at least one combustion chamber through the at least one clean gas pipe to the at least one heat exchanger, wherein the clean gas variably heats the sucked off exhaust gases at least temporarily; the clean gas exiting the at least one heat exchanger is transported to at least one heat consumer, wherein a varying amount of heat is taken from the clean gas, which amount is used for varyingly heating of the at least one drying tunnel; and the clean gas is released into atmosphere as clean gas exhaust, wherein an algorithm of at least one thermodynamic control unit is based on: Equation I: Control Equation for a measuring station downstream of the heat exchanger:
?.sub.TNV[W]+?.sub.AG[W]=?.sub.WA[W]+?.sub.RGD[W]; Equation II: Control Equation relative to a vantage point of the at least one thermal post-combustion facility:
?.sub.TNV[W]=?.sub.WA[W]+?.sub.RGD[W]??.sub.AG[W]; Equation III: control difference ? upstream of the control unit:
?={?.sub.WA[W]+?.sub.RGD[W]??.sub.AG[W]}??.sub.TNV[W]; with ?.sub.WA [W]+?.sub.RGD [W]??.sub.AG [W]=target value and ?.sub.TNV [W]=actual value, wherein the target value is defined as follows: (i) ?.sub.WA [W] as a heat reduction of the drying plant to be compensated, (ii) ?.sub.AG [W] as a recuperation of heat from the drying plant to be compensated/included, and (iii) ?.sub.RGD [W] as an energy content of the clean gas exhaust; Regulating Variable: a volume stream {dot over (V)} at normal or standard conditions (temperature=273.15 K, pressure=1013.25 mbar); and Equation IV: a combustion chamber temperature:
T.sub.BK=f({dot over (V)}.sub.variabel), wherein {dot over (V)}.sub.variabel=volume stream of the clean gas in the at least one clean gas pipe.

10. The process as claimed in claim 9, wherein the clean gas released into the atmosphere is either released directly, through a chimney or from a downstream waste heat boiler.

11. The process as claimed in claim 9, wherein Equation IV defines a setting window, wherein the combustion chamber temperature at a minimum volume stream is between 600? C. and 800? C., and at a maximum volume stream is between 700? C. and 900? C., and wherein both temperature ranges are chosen such that they do not overlap.

12. The process as claimed in claim 11, wherein the volume streams are in the range of from 3000 m.sup.3 per hour to 30.000 m.sup.3 per hour under normal standard conditions.

13. The process as claimed in claim 9, wherein the following inputs are entered into the at least one thermodynamic control unit: at least one first input of measured values of a temperature of the exhaust gases in the at least one exhaust gas pipe downstream from the at least one heat exchanger and the at least one cold bypass from at least one first measuring station; at least one second input of measured values of a temperature of the exhaust gas from at least one second measuring station; at least one third input of measured values of at least one combustion chamber temperature from at least one third measuring station; at least one fourth input of measured values of a temperature from at least one fourth measuring station; at least one fifth input of measured values of volume streams of the clean gas in the at least one clean gas pipe from at least one sixth measuring station; and at least one sixth input of measured values of a temperature of the clean gas in the at least one clean gas pipe downstream from the at least one heat exchanger, wherein at least one first actuator is controlled by at least one first output of the target values from the at least one thermodynamic control unit for the at least one combustion chamber temperature; wherein the at least one control station is controlled by at least one second output of target values from the at least one thermodynamic control unit for exhaust gas in the at least one cold bypass; and wherein at least one second actuator is controlled by at least one third output of target values from the at least one thermodynamic control unit for at least one blower connected to the at least one exhaust gas pipe from the at least one drying tunnel.

14. The process as claimed in claim 9, wherein two or more drying plants are linked with one thermal post-combustion facility, wherein the energy content of the clean gas exhaust is controlled at the fourth measuring station by the specification of a target value for a temperature of the clean gas in the at least one clean gas pipe downstream of the at least one heat consumer.

Description

SHORT DESCRIPTION OF THE FIGURES

(1) The drying plant of the invention and the process of the invention are explained in detail by the Examples with reference to the FIGS. 1 to 3. The FIGS. 1 to 3 serve to illustrate the principles and the functions of the drying plant of the invention and of the drying process of the invention and, therefore, need not be drawn true to scale.

(2) FIG. 1 shows the flowchart of a thermodynamically controlled drying plant T of the invention for drying of coated drying goods TG,

(3) FIG. 2 shows the detailed flowchart of the control R of the cold bypass BP of FIG. 1, and

(4) FIG. 3 shows the emission setting window EST=combustion chamber temperature T.sub.BK [? C.] as a function of the volume stream {dot over (V)}.sub.variable [m.sup.3 per hour under standard conditions] of the clean gas RG in the clean gas pipe L.sub.RG.

(5) In the FIGS. 1 to 3, the reference signs have the following meaning: 1 Measuring station for the exhaust gas temperature T.sub.AG [? C.] in the exhaust gas pipe L.sub.AG 2 Measuring station for the volume stream {dot over (V)} [m.sup.3/hour under standard conditions] off the exhaust gas AG in the exhaust gas pipe L.sub.AG 3 Actuator for the blower GBL 4 Measuring station T.sub.WT [? C.] off the exhaust gas AG.sub.WT upstream off the combustion chamber BK 5 Control valve in the cold bypass BP, regulated by the control R 6 Actuator for the valve 7 in the natural gas pipe L.sub.EG 7 Pilot valve for the natural gas EG 8 Measuring station for the temperature T.sub.NWA [? C.] of the clean gas RG in the clean gas pipe L.sub.RG downstream of the heat exchanger WT and upstream of the consumer WA 9 Measuring station for the temperature T.sub.Kamin of the clean gas RG in the clean gas pipe L.sub.RG downstream of the heat consumer WA 10 Measuring station for the temperature T.sub.BK [? C.] of the clean gas RG in the clean gas pipe L.sub.RG upstream of the heat exchanger WT 11 Measuring station for the temperature T.sub.BK [? C.] of the clean gas RG in the combustion chamber BK a Position open AG Exhaust gas from the drying tunnel TT AG.sub.WT Exhaust gas in the exhaust gas pipe L.sub.AG downstream of the heat exchanger WT BK Combustion chamber BP Cold bypass BR Burner ?.sub.AG Energy flow exhaust gas [W] ?.sub.RGD Energy flow clean gas over the roof [W] ?.sub.TNV Energy flow thermal post-combustion facility [W] ?.sub.WA Energy flow heat consumer [W] EG Fuel ESF Emission setting window FL Flame FU Frequency converter GBL Blower or exhaust gas ventilator HZ.sub.TT Heater of the drying tunnel TT by the heat consumer(s) WA in1 Input of the measured values of the temperature T.sub.WT of the exhaust gases AG.sub.WT in the exhaust gas pipe L.sub.AG WT (measuring station 4) in2 Input of the measured values T.sub.AG of the temperature [? C.] of the exhaust gases AG in L.sub.AG upstream of WT (measuring station 1) in3 Input of the measured values of the combustion chamber temperature T.sub.BK [? C.] (measuring station 11) in4 Input of the measured values of the temperature T.sub.Kamin [? C.] (measuring station 9) in5 Input of the measured values of the volume stream {dot over (V)} variabel [m.sup.3/hour under standard conditions] off AG in L.sub.AG (measuring station 2) in6 Input of the measured values of the temperature T.sub.R [? C.] of the clean gas RG in the clean gas pipe L.sub.RG downstream of the heat exchanger WT (measuring station 8) i. N. Standard conditions: temperature=273.15 K, pressure=1013.25 mbar K Chimney L.sub.AG Pipe for the exhaust gas AG L.sub.EG Pipe for the fuel EG L.sub.RG Pipe for the clean gas RG LTG Coated drying goods out1 Output of target volumes for T.sub.BK [? C.] for controlling of the actuator 6 out2 Output of the target values T.sub.WT [? C.] to the control station R out3 Output of the target values for the volume stream {dot over (V)}.sub.variabel [m.sup.3/hour under standard conditions] of the exhaust gas AG in the exhaust gas pipe L.sub.AG to the actuator 3 R Control station in the cold bypass BP RGD Clean gas over the roof SK Skid T Drying plant T.sub.AG Exhaust gas temperature [? C.] (measuring station 1) T.sub.Kamin Temperature [? C.] of the clean gas RG in in the clean gas pipe L.sub.RG downstream of the heat consumer WA (measuring stations 9) T.sub.BK Temperature [? C.] of the combustion chamber BK (measuring station 11) T.sub.NWA Temperature [? C.] of the clean gas RG in the clean gas pipe L.sub.RG downstream of the heat exchanger WT and upstream of the heat consumer WA (measuring station 8) T.sub.RG Temperature [? C.] of the clean gas RG in the clean gas pipe L.sub.RG downstream of the combustion chamber BK [? C.] (measuring station 10) T.sub.WT Temperature of the exhaust gas AG.sub.WT in the exhaust gas pipe L.sub.AG downstream of the heat exchanger WT [? C.] (measuring station 4) TDR Thermodynamic control TNV Thermal post-combustion TT Drying tunnel {dot over (V)} Volume stream [m.sup.3/hour under standard conditions] {dot over (V)}.sub.variabel Volume stream of the clean gas RG in the clean gas pipe L.sub.RG [m.sup.3/hour under standard conditions] {dot over (V)}.sub.min. Minimum volume stream of the clean gas RG in the clean gas pipe L.sub.RG [m.sup.3/hour under standard conditions] {dot over (V)}.sub.max. Maximum volume stream of the clean gas RG in the clean gas pipe L.sub.RG [m.sup.3/hour under standard conditions] VFR Traverse or conveying direction VOC Volatile Organic Compounds W Power in Watt WA Heat consumer z Position closed ?T.sub.RG Temperature of the clean gas RG (measuring station 8) rises ?T.sub.RG Temperature of the clean gas RG (measuring station 8) decreases

DETAILED DESCRIPTION OF THE FIGURES

FIGS. 1 to 3

(6) The drying plant of the invention T was designed for minimum volume streams {dot over (V)}.sub.min. of 5,000 m.sup.3/hour and for maximum volume streams {dot over (V)}.sub.max. of 10,000 m.sup.3/hour. The emission setting window ESF was predetermined by corner points of 680? C. and 690? C. as well as 720? C. and 730? C. Plant components which were particularly thermally stressed were built mainly with stainless steel. Plant components which were less thermally stressed were built mainly with shock resistant and thermally stable plastics made flame retardant, if necessary. The drying plant T was electronically controlled by a thermodynamic control. The drying plant T was subject to an expert opinion relating to explosion.

(7) The drying plant T of the invention for drying of coated drying goods LTG, in particular, car bodies, comprised a drying tunnel TT through which the car bodies LTG were conveyed in the conveying direction VFR on skids SK, a pipe L.sub.AG for the exhaust gas AG containing volatile organic compounds VOC from the drying tunnel TT, a blower GBL controlled by an actuator 3 for the controlled transfer of the exhaust gas AG to a heat exchanger WT, a heat exchanger WT, wherein the exhaust gas AG was variably heated by the clean gas RG in the clean gas pipe L.sub.RG, an exhaust gas pipe L.sub.AG downstream from the heat exchanger WT, through which the exhaust gas AGWT which was heated to variable temperatures TAG, was transported to the burner BR in variable amounts, a cold bypass BP circumventing the heat exchanger WT and connecting the exhaust gas pipe L.sub.AG upstream of the heat exchanger WT with the exhaust gas pipe L.sub.AG downstream of the heat exchanger WT, which cold bypass BP was controlled by an electronically regulated control unit R, a fuel pipe through which the fuel EG, in the present case, natural gas EG, was transported in a controlled way to the burner BR, a burner BR in the combustion chamber BK of the thermal post-combustion facility TNV, a clean gas pipe L.sub.RG, through which the clean gas RG having variable temperatures T.sub.BK is transported from the combustion chamber BK to the heat exchanger WT, where it was variably cooled down by the exhaust gas AG, a clean gas pipe L.sub.RG through which the variably cooled clean gas RG was led to a heat consumer WA, a heater HZ.sub.TT which heated the drying tunnel variably by the heat consumer WA, and a clean gas pipe L.sub.RG, through which the clean gas RG, which was further cooled down, is led to a chimney K, from where the clean gas RG is released over the roof into the atmosphere.

(8) For the purposes of the electronic control, the drying plant T of the invention contained a measuring station 1 for the temperature T.sub.AG [? C.] of the exhaust gas AG, a measuring station 2 for the volume stream {dot over (V)} of the exhaust gas AG in the at least one exhaust gas pipe L.sub.AG, a controllable actuator 3 for the blower GBL, a measuring station 4 for the temperature T.sub.WT of the exhaust gas AG.sub.TW in the exhaust gas pipe L.sub.AG downstream of the heat exchanger WT and upstream of the burning chamber BK, a pilot valve 5 in the cold bypass BP which is controlled by a control unit R, a controllable actuator 6 for the control valve 7 in the fuel pipe L.sub.EG, a pilot valve 7 for the fuel EG, in the present case, natural gas EG, a measuring station 8 for the temperature T.sub.RG of the clean gas RG in the clean gas pipe him downstream of the heat exchanger WT, a measuring station 9 for the temperature T.sub.Kamin of the clean gas RGD in the clean gas pipe L.sub.RG downstream of the at least one heat consumer WA, a measuring station 10 for the temperature T.sub.RG of the clean gas RG in the clean gas pipe L.sub.RG upstream from the heat exchanger WT, and a measuring station 11 for the temperature T.sub.BK in the combustion chamber BK.

(9) As the measuring instruments, customary and known instruments for measurements at high temperatures and hot gas streams are used.

(10) For purposes of the electronic control of the drying plant T, the thermodynamic control unit TDR received an input in1 of the measured values of the temperature T.sub.WT of the exhaust gas AG.sub.WT in the exhaust gas pipe L.sub.AG downstream of the heat exchanger WT from the measuring station 4, an input in2 of the measured values of the temperature T.sub.AG [? C.] of the exhaust gas AG from the measuring station 1, an input in3 for the measured values of the combustion chamber temperature T.sub.BK from the measuring station 11, an input in4 for the measured values of the temperature T.sub.Kamin from the measuring station 9, an input in5 for the measured values of the volume stream {dot over (V)}.sub.variabel of the clean gas RG in the clean gas pipe L RG from the measuring station 2, an input in6 of the target values of the temperature T.sub.RG of the team gas. RG in the clean gas pipe L.sub.RG downstream of the heat exchanger WT from the measuring station 8.

(11) For the purposes of control, the thermodynamic measuring station TDR put out after the calculation an output out1 of the target values for TBK to the actuator 6, an output out2 of the target values TWT to the control unit R, and an output out3 of the target values of the volume streams {dot over (V)}.sub.variabel [m.sup.3/hour under standard conditions].

(12) The controlling algorithm was based on the following mathematical correlations:

(13) The controlling equation for the measuring station 8 downstream of the heat exchanger WT was equation I:
?.sub.TNV[W]+?.sub.AG[W]=?.sub.WA[W]+?.sub.RGD[W](I).

(14) Seen from the vantage station of the post-combustion facility, the controlling equation became equation II:
?.sub.TNV[W]=?.sub.WA[W]+?.sub.RGD[W]??.sub.AG[W](II)

(15) Thereby, the control difference ? upstream of the control unit was obtained as equation III:
?={?.sub.WA[W]+?.sub.RGD[W]??.sub.AG[W]}??.sub.TNV[W](III)
with ?.sub.WA [W]+?.sub.RGD [W]??.sub.AG [W]=target value and ?.sub.TNV [W]=actual value.

(16) The target value could be defined more precisely: (i) ?.sub.WA [W] as the heat reduction of the dryer T to be compensated, (ii) ?.sub.AG [W] as the recuperation of heat from the dryer T to be compensated/included and (iii) ?.sub.RGD [W] as the energy content of the clean gas exhaust over the roof RGD, which is established with the target value T.sub.Kamin for calculating the energy content RGD.

(17) The regulating variable is the volume stream {dot over (V)} at normal or standard conditions (i.N.: Temperature=273.15 K, pressure=1013.25 mbar).

(18) The combustion chamber temperature TBK followed in turn, the equation IV:
T.sub.BK=f({dot over (V)}.sub.variabel)(IV),
wherein {dot over (V)}.sub.variabel=volume stream of the clean gas RG in the clean gas pipe L.sub.RG [m.sup.3 per hour under normal standard conditions].

(19) For the heater HZ.sub.TT of the drying zone TT, the thermal power ?.sub.WA [W] was taken from the heat consumers WA.

(20) The drying plant T of the invention could be combined, for example, with the configuration described in detail in the Figure of the German patent DE 10 2008 034 746 B4. The following reference signs in italic refer to the known Figure. In the drying plant, the clean gas exited the thermal post-combustion facility TNV 9 by the clean gas pipe 24, 24a, 24b and 24c. The three last mentioned sections were laid section by section at the floor of the drying tunnel so that the drying goods could be particularly well heated from below. The clean gas pipes exited the floor of the drying tunnel and the clean gas contained therein heated the circulating gas in the circulating gas recuperators 10 and 12, which circulating gas was fed to them by the circulating gas pipes 17 from the drying tunnel and was then led back into the drying tunnel. The clean gas which was cooled down was further cooled in the fresh air recuperator 14 before the discharge into the atmosphere, and the fresh air heated in this way was again led back into the drying facility via the fresh air pipes 15a and 15b.

(21) This way, not only the significant advantages of the drying plant T of the invention could be combined with the advantages of the drying plant according to the German patent DE 10 2008 034 746 B4 thus resulting in new particular advantages, but significant energy savings and a significant reduction of the emissions of NOx, complete carbon, carbon monoxide and formaldehyde could be achieved. When using a combustion with oil, sulfur dioxide was also observed.

(22) With the combination of the drying plant T of the invention with a compact thermal post-combustion facility TNV of Wenker GmbH & Co. KG, Ahaus, Germany, the thermal post-combustion facility TNV could be run with significant more stable emissions, and the controllable performance range of the TNV could be considerably extended when one held the exhaust gas temperature T.sub.WT upstream from the combustion chamber BK constant with the help of the control station R of the cold bypass BP and changed the combustion chamber temperature. TBK dependent on the volume stream {dot over (V)}.sub.min. to {dot over (V)}.sub.max. within the limits Minimum combustion chamber temperature TBK to maximum combustion chamber temperature TBK.

(23) The possibility of circumventing the intermission set up moreover enabled the drying plant T of the invention to let drying goods LTG, in particular, car bodies, enter at low combustion chamber temperatures T.sub.BK. Therefore, the minimum amount of air could be used maximally in order to dry the car bodies, which was not possible in the prior art drying processes, in particular, during the usage of the intermission set up.