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THERMODYNAMICALLY REGULATED METHOD AND THERMODYNAMICALLY REGULATED DRYING SYSTEM FOR DRYING GOODS TO BE DRIED

20210293482 · 2021-09-23

    Inventors

    Cpc classification

    International classification

    Abstract

    The invention relates to a drying system (T) according to FIG. 1 for drying goods to be dried (LTG), comprising—a 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 (T) for the drying of drying goods (LTG), comprising at least one drying tunnel (TT) through which the drying goods (LTG) can be conveyed in the conveying direction (VFR), at least one pipe (L.sub.AG) for the exhaust gas (AG) containing volatile organic compounds (VOC) out of the at least one drying tunnel (TT), at least one blower (GBL) controlled by a frequency converter (FU) for the controlled transport of the exhaust gas (AG) to at least one heat exchanger (WT), at least one heat exchanger (WT), wherein the exhaust gas (AG) can be heated variably by the clean gas (RG) in the at least one clean gas pipe (L.sub.RG), at least one exhaust gas pipe (L.sub.AG) downstream of the at least one heat exchanger (WT) through which the exhaust gas (AG.sub.WT) which is heatable to variable temperatures (T.sub.AG), is transportable in varying amounts to the at least one burner (BR) in the at least one combustion chamber (BK) of at least one thermal post-combustion facility (TNV), at least one cold bypass (BP) circumventing the at least one heat exchanger (WT) and connecting the at least one exhaust gas pipe (L.sub.AG) upstream of the at least one heat exchanger (WT) with the at least one exhaust gas pipe (L.sub.AG) downstream of the at least one heat exchanger (WT), which cold bypass (BP) is controllable with at least one electronically regulated control station (R), at least one pipe (L.sub.EG) through which the fuel (EG) is controllably transportable to the at least one burner (BR), at least one clean gas pipe (L.sub.RG), through which the clean gas (RG) is transportable from the at least one combustion chamber (BK) having variable temperatures (T.sub.BK) to the at least one heat exchanger (WT), wherein it is variably coolable by the exhaust gas (AG), at least one clean gas pipe (L.sub.RG) through which the variably cooled down clean gas (RG) is transportable from the at least one heat exchanger (WT) to the at least one heat consumer (WA), at least one heater (HZ.sub.TT), by which the at least one drying zone (TT) is heatable by the at least one heat consumer (WA), at least one clean gas pipe (L.sub.RG), through which the clean gas (RG) which is further cooled down, is transportable to at least one chimney (K), whence the clean gas is releasable into the atmosphere.

    2. The thermodynamically controllable drying plant (T) as claimed in claim 1, characterized in that it contains at least one measuring station (1) for the temperature (T.sub.AG) [° C.] of the exhaust gas (L.sub.AG), at least one 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), at least one controllable actuator (3) for the blower (GBL), controllable by at least one frequency converter (FU), at least one 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), at least one pilot valve (5) in the cold bypass (BP) which is controlled by a control unit (R), at least one controllable actuator (6) for the control valve (7) in the fuel pipe (L.sub.EG), at least one control valve (7) connected upstream of the burner (BR) for the fuel (EG), at least one measuring station (8) for the temperature (T.sub.NWA) of the clean gas (RG) in the clean gas pipe downstream of the heat exchanger (WT), at least one measuring station (9) for the temperature (T.sub.Kamin) of the clean gas (RG) in the clean gas pipe (L.sub.RG) downstream of the at least one heat consumer (WA), at least one 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), or, alternatively, at least one measurement point (8) downstream of the at least one heat exchanger (WT), or alternatively, at least one measuring point (8) downstream of the at least one heat exchanger (WT) if the at least one combustion chamber (BK) and the at least one heat exchanger (WT) form at least one compact unit in the at least one thermal post-combustion installation (TNV), and a measuring station (11) for the temperature (T.sub.BK) in the at least one combustion chamber (BK) of the at least one post-combustion facility (TNV).

    3. The thermodynamically controllable drying plant (T) as claimed in claim 1, characterized in that the at least one heat consumer (WA) is acting as the heater (HZ.sub.TT) for the at least one drying tunnels (TT).

    4. The thermodynamically controllable drying plant (T) as claimed in claim 1, characterized in that it is controllable with at least one thermodynamic control station (TDR).

    5. The thermodynamically controllable drying plant (T) as claimed in claim 4, characterized in that the at least one thermodynamic control station (TDR) contains at least one 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), at least one input (in2) of the measured values of the temperature (T.sub.AG) [° C.] of the exhaust gas (AG) from the measuring station (1), at least one input (in3) for the measured values of the combustion chamber temperature (T.sub.BK) from the measuring station (11), at least one input (in4) for the measured values of the temperature (T.sub.Kamin) from the measuring station (9), at least one 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.sub.RG) from the measuring station (2), at least one input (in6) of the target values of the temperature (T.sub.RG) of the clean gas (RG) in the clean gas pipe (L.sub.RG) downstream of the heat exchanger (WT) from the measuring station (8), as well as at least one output (out1) of the target values for (TBK) to the actuator (6), at least one output (out2) of the target values (TWT) to the control unit (R), and at least one output (out3) of the target values of the volume streams {dot over (V)}.sub.variabel of the clean gas (RG) in the clean gas pipe (L.sub.RG) to at least one actuator (3).

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

    7. The thermodynamically controlled drying plant (T) as claimed in claim 1, characterized in that the drying goods (LTG) 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 of all kind 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 (T) as claimed in claim 7, characterized in that the drying goods (LTG) are building parts for architectural purposes like 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 the drying of drying goods (LTG) in at least one thermodynamically controllable drying plant (T) as claimed in claim 1, wherein the drying goods (LTG) are conveyed through at least one drying tunnel (TT) in conveying direction (VFR) and thereby dried, characterized in that the volatile organic compounds (VOC) containing exhaust gases (AG) generated thereby are sucked off through at least one exhaust gas pipe (L.sub.AG) from the at least one drying tunnel (TT), (ii) are transported by at least one blower (GBL) controlled by a frequency converter (FU) to at least one heat exchanger (WT), whereby the amount of the sucked off exhaust gases (AG) is controlled, (iii) are, at least temporarily, heated to variable exhaust gas temperatures (T.sub.AG) in at least one heat exchanger (WT) by the clean gas (RG) in the least one clean gas pipe (L.sub.RG) upstream of the at least one thermal post-combustion chamber facility (TNV), (iv) are transported through at least one cold bypass (BP) circumventing the at least one heat exchanger (WT) and connecting the at least one exhaust gas pipe (L.sub.AG) upstream and downstream of the at least one heat exchanger (WT), the cold bypass (BP) being regulated by at least one control valve (7) controlled by at least one control station (R), which pilot valve (7) remains temporarily open or closed or remains partially or completely open or closed during the complete drying process, whereby the exhaust gas temperature (T.sub.AG) is kept constant or is varied if necessary, (v) are transported through at least one additional exhaust gas pipe (L.sub.AG) from the at least one heat exchanger (WT) to the at least one burner (BR) and (vi) are mixed with the fuel (EG) which is supplied by at least one fuel pipe (L.sub.EG) in varying amounts, and (vii) are burned in the at least one burner (BR) in the at least one combustion chamber (BK) of the at least one thermal post-combustion facility (TNV) in at least one flame (FL) at variable combustion chamber temperatures (T.sub.BK) whereby (viii) the resulting clean gas (RG) having variable temperatures (T.sub.RG) is transported out of the at least one combustion chamber (BK) through at least one clean gas pipe (L.sub.RG) to the at least one heat exchanger (WT), wherein it variably heats the sucked off exhaust gases (AG) at least temporarily, (ix) the clean gas (RG) exiting the at least one heat exchanger (WT) is transported to at least one heat consumer (WA), wherein a varying amount of heat is taken from the clean gas (RG), which amount is used for varyingly heating of the at least one drying tunnel (TT), whereupon (x) the clean gas (RG) is released over the roof into the atmosphere.

    10. The process as claimed in claim 9, characterized in that the clean gas (RG) in the process step (x) is either released directly or through a chimney (K) or from a downstream waste heat boiler.

    11. The process for thermodynamic control (TDR) as claimed in claim 9 for drying goods to be dried (TG) in at least one drying installation (T), characterized in that the algorithm of the at least one ordinary control unit (TDR) is based on the following correlations: Equation I: Control Equation for a measuring station (8) downstream of the heat exchanger (WT):
    Ė.sub.TNV[W]+Ė.sub.AG[W]=Ė.sub.WA[W]+Ė.sub.RGD[W]  (I); Equation II: Control Equation 1 seen from the vantage point of the post-combustion facility:
    Ė.sub.TNV[W]=Ė.sub.WA[W]+Ė.sub.RGD[W]−Ė.sub.AG[W]  (II); Equation III: control difference Δ upstream of the control unit:
    Δ={Ė.sub.WA[W]+Ė.sub.RGD[W]−Ė.sub.AG[W]}−Ė.sub.TNV[W]  (III), With Ė.sub.WA [W]+Ė.sub.RGD [W]−Ė.sub.AG [W]=target value and Ė.sub.TNV [W]=actual value, wherein the target value is defined as follows: (i) Ė.sub.WA [W] as the heat reduction of the dryer T to be compensated, (ii) Ė.sub.AG [W] as the recuperation of heat from the dryer T to be compensated/included and (iii) Ė.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; Regulating Variable: The volume stream {dot over (V)} at normal or standard conditions (i.N.: Temperature=273,15 K, pressure=1013,25 mbar); and Equation IV: The combustion chamber temperature (TBK):
    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].

    12. The process as claimed in claim 11, characterized in that the Equation IV defines a setting window (ESF), wherein the combustion chamber temperature (TBK) at a minimum volume stream {dot over (V)}.sub.min. is between 600° C. and 800° C., and at a maximum volume stream {dot over (V)}.sub.max. is between 700° C. and 900° C., whereby, however, both temperature ranges are chosen such that they do not overlap.

    13. The process as claimed in claim 11, characterized in that the volume streams V are in the range of from 3000 m.sup.3 per hour to 30,000 m.sup.3 per hour under normal standard conditions.

    14. The process as claimed in claim 11, characterized in that with at least one thermodynamic control station (TDR), at least one input (in2) of the measured values of the temperature (T.sub.WT) of the exhaust gases (AG.sub.WT) in the at least one exhaust gas pipe (L.sub.AG) downstream from the at least one heat exchanger (WT) and the cold bypass (BP) from the at least one measuring station (4), at least one input (in2) of the measured values of the temperature (T.sub.AG) of the exhaust gas (AG) from the at least one measuring station (2), at least one input (in3) of the measured values of the at least one combustion chamber temperature (T.sub.BK) from the at least one measuring station (11), at least one input (in4) of the measured values of the temperature (T.sub.Kamin) from the at least one measuring station (9), at least one input (in5) for the measured values of the volume streams {dot over (V)}.sub.variabel of the clean gas (RG) in the at least one clean gas pipe (L.sub.RG) from the at least one measuring station V, and at least one input (in6) of the measured values (8) of the temperature (T.sub.RG) of the clean gas (RG) in the at least one clean gas pipe (L.sub.RG) downstream from the at least one heat exchanger WT) are entered into the thermodynamic control unit (TDR), whereby the at least one actuator (6) is controlled by the at least one output (out1) of the target values for (T.sub.BK), the at least one control unit (R) is controlled by the at least one output (out2) of the target values (T.sub.RG), and the at least one actuator (3) is controlled by the at least one output (out3) of the target values of the volume stream {dot over (V)}.sub.variabel of the clean gas (RG) in the at least one clean gas pipe (L.sub.RG).

    15. The process as claimed in claim 9, characterized in that two or more drying plants (T) according to claim 1 are linked with one thermal post-combustion facility (TNV), whereby the energy content of the clean gas (RGD) over the roof is controlled at the measuring station (9) by the specification of the target value for the temperature (T.sub.Kamin) of the clean gases (RG) in the clean gas pipe (LRG) downstream of the heat consumer (WA).

    Description

    SHORT DESCRIPTION OF THE FIGURES

    [0087] 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.

    [0088] FIG. 1 shows the flowchart of a thermodynamically controlled drying plant T of the invention for drying of coated drying goods TG,

    [0089] FIG. 2 shows the detailed flowchart of the control R of the cold bypass BP of FIG. 1, and

    [0090] 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.

    [0091] In the FIGS. 1 to 3, the reference signs have the following meaning: [0092] 1 Measuring station for the exhaust gas temperature T.sub.AG [° C.] in the exhaust gas pipe L.sub.AG [0093] 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 [0094] 3 Actuator for the blower GBL [0095] 4 Measuring station T.sub.WT [° C.] off the exhaust gas AG.sub.WT upstream off the combustion chamber BK [0096] 5 Control valve in the cold bypass BP, regulated by the control R [0097] 6 Actuator for the valve 7 in the natural gas pipe L.sub.EG [0098] 7 Pilot valve for the natural gas EG [0099] 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 [0100] 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 [0101] 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 [0102] 11 Measuring station for the temperature T.sub.BK [° C.] of the clean gas RG in the combustion chamber BK [0103] a Position “open” [0104] AG Exhaust gas from the drying tunnel TT [0105] AG.sub.WT Exhaust gas in the exhaust gas pipe L.sub.AG downstream of the heat exchanger WT [0106] BK Combustion chamber [0107] BP Cold bypass [0108] BR Burner [0109] Ė.sub.AG Energy flow exhaust gas [W] [0110] Ė.sub.RGD Energy flow clean gas over the roof [W] [0111] Ė.sub.TNV Energy flow thermal post-combustion facility [W] [0112] Ė.sub.WA Energy flow heat consumer [W] [0113] EG Fuel [0114] ESF Emission setting window [0115] FL Flame [0116] FU Frequency converter [0117] GBL Blower or exhaust gas ventilator [0118] HZ.sub.TT Heater of the drying tunnel TT by the heat consumer(s) WA [0119] 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) [0120] 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) [0121] in3 Input of the measured values of the combustion chamber temperature T.sub.BK [° C.] (measuring station 11) [0122] in4 Input of the measured values of the temperature T.sub.Kamin [° C.] (measuring station 9) [0123] 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) [0124] 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) [0125] i. N. Standard conditions: temperature=273,15 K, pressure=1013,25 mbar [0126] K Chimney [0127] L.sub.AG Pipe for the exhaust gas AG [0128] L.sub.EG Pipe for the fuel EG [0129] L.sub.RG Pipe for the clean gas RG [0130] LTG Coated drying goods [0131] out1 Output of target volumes for T.sub.BK [° C.] for controlling of the actuator 6 [0132] out2 Output of the target values T.sub.WT [° C.] to the control station R [0133] 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 [0134] R Control station in the cold bypass BP [0135] RGD Clean gas over the roof [0136] SK Skid [0137] T Drying plant [0138] T.sub.AG Exhaust gas temperature [° C.] (measuring station 1) [0139] 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) [0140] T.sub.BK Temperature [° C.] of the combustion chamber BK (measuring station 11) [0141] 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) [0142] 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) [0143] 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) [0144] TDR Thermodynamic control [0145] TNV Thermal post-combustion [0146] TT Drying tunnel [0147] {dot over (V)} Volume stream [m.sup.3/hour under standard conditions] [0148] {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] [0149] {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] [0150] {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] [0151] VFR Traverse or conveying direction [0152] VOC Volatile Organic Compounds [0153] W Power in Watt [0154] WA Heat consumer [0155] z Position “closed” [0156] ↑T.sub.RG Temperature of the clean gas RG (measuring station 8) rises [0157] ↓T.sub.RG Temperature of the clean gas RG (measuring station 8) decreases

    DETAILED DESCRIPTION OF THE FIGURES

    FIGS. 1 to 3

    [0158] 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.

    [0159] The drying plant T of the invention for drying of coated drying goods LTG, in particular, car bodies, comprised [0160] a drying tunnel TT through which the car bodies LTG were conveyed in the conveying direction VFR on skids SK, [0161] a pipe L.sub.AG for the exhaust gas AG containing volatile organic compounds VOC from the drying tunnel TT, [0162] a blower GBL controlled by an actuator 3 for the controlled transfer of the exhaust gas AG to a heat exchanger WT, [0163] 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, [0164] an exhaust gas pipe L.sub.AG downstream from the heat exchanger WT, through which the exhaust gas AG.sub.WT which was heated to variable temperatures TAG, was transported to the burner BR in variable amounts, [0165] 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, [0166] 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, [0167] a burner BR in the combustion chamber BK of the thermal post-combustion facility TNV, [0168] 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, [0169] a clean gas pipe L.sub.RG through which the variably cooled clean gas RG was led to a heat consumer WA, [0170] a heater HZ.sub.TT which heated the drying tunnel variably by the heat consumer WA, and [0171] 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.

    [0172] For the purposes of the electronic control, the drying plant T of the invention contained [0173] a measuring station 1 for the temperature T.sub.AG [° C.] of the exhaust gas AG, [0174] a measuring station 2 for the volume stream V of the exhaust gas AG in the at least one exhaust gas pipe L.sub.AG, [0175] a controllable actuator 3 for the blower GBL, [0176] 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, [0177] a pilot valve 5 in the cold bypass BP which is controlled by a control unit R, [0178] a controllable actuator 6 for the control valve 7 in the fuel pipe L.sub.EG, [0179] a pilot valve 7 for the fuel EG, in the present case, natural gas EG, [0180] 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, [0181] 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, [0182] 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 [0183] a measuring station 11 for the temperature T.sub.BK in the combustion chamber BK.

    [0184] As the measuring instruments, customary and known instruments for measurements at high temperatures and hot gas streams are used.

    [0185] For purposes of the electronic control of the drying plant T, the thermodynamic control unit TDR received [0186] 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, [0187] an input in2 of the measured values of the temperature T.sub.AG [° C.] of the exhaust gas AG from the measuring station 1, [0188] an input in3 for the measured values of the combustion chamber temperature T.sub.BK from the measuring station 11, [0189] an input in4 for the measured values of the temperature T.sub.Kamin from the measuring station 9, [0190] 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, [0191] 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.

    [0192] For the purposes of control, the thermodynamic measuring station TDR put out after the calculation [0193] an output out1 of the target values for TBK to the actuator 6, [0194] an output out2 of the target values TWT to the control unit R, and [0195] an output out3 of the target values of the volume streams {dot over (V)}.sub.variabel [m.sup.3/hour under standard conditions].

    [0196] The controlling algorithm was based on the following mathematical correlations:

    [0197] The controlling equation for the measuring station 8 downstream of the heat exchanger WT was equation I:


    Ė.sub.TNV[W]+Ė.sub.AG[W]=Ė.sub.WA[W]+Ė.sub.RGD[W]  (I).

    [0198] Seen from the vantage station of the post-combustion facility, the controlling equation became equation II:


    Ė.sub.TNV[W]=Ė.sub.WA[W]+Ė.sub.RGD[W]−Ė.sub.AG[W]  (II)

    [0199] Thereby, the control difference Δ upstream of the control unit was obtained as equation III:


    Δ={Ė.sub.WA[W]+Ė.sub.RGD[W]−Ė.sub.AG[W]}−Ė.sub.TNV[W]  (III)

    with Ė.sub.WA [W]+Ė.sub.RGD [W]−Ė.sub.AG [W]=target value and Ė.sub.TNV [W]=actual value.

    [0200] The target value could be defined more precisely: [0201] (i) Ė.sub.WA [W] as the heat reduction of the dryer T to be compensated, [0202] (ii) Ė.sub.AG [W] as the recuperation of heat from the dryer T to be compensated/included and [0203] (iii) Ė.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.

    [0204] 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).

    [0205] 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].

    [0206] For the heater HZ.sub.TT of the drying zone TT, the thermal power Ė.sub.WA [W] was taken from the heat consumers WA.

    [0207] 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.

    [0208] 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.

    [0209] 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”.

    [0210] 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.