AIR HEATER FOR A DRYING TOWER AND DRYING TOWER FOR DRYING A PRODUCT TO BE DRIED

Abstract

An air heater is used for a drying tower, wherein the air heater includes a combustion chamber, a burner, an air heating chamber, a process air access, a process air exit and/or a flue gas exit. During operation of the air heater, a process air is supplied to the air heating chamber by way of the process air access, a fuel is burned by means of the burner, a heat thus generated in the combustion chamber is transferred to the process air in the air heating chamber and the heated process air is discharged out of the air heater by way of the process air exit, and the air heater comprises an expendable combustion chamber, wherein the expendable combustion chamber is disposed within the combustion chamber. Further, a drying tower is used for drying a product to be dried with an air heater.

Claims

1. An air heater for a drying tower, wherein the air heater comprises: a combustion chamber, a burner, an air heating chamber, a process air access, and a process air exit and/or a flue gas exit, wherein the air heater is designed in such a manner that a process air is supplied to the air heating chamber by way of the process air access, a heat generated in the combustion chamber by the burner is transferred to the process air in the air heating chamber, wherein a heated process air is discharged out of the air heater by way of the process air exit, and wherein the air heater comprises an expendable combustion chamber and the expendable combustion chamber is disposed within the combustion chamber.

2. The air heater according to claim 1, wherein the expendable air chamber is disposed around a flame or a part of the flame of the burner.

3. The air heater according to claim 1, wherein the expendable combustion chamber has several openings.

4. The air heater according to claim 3, wherein the openings are distributed across a lateral surface of the expendable combustion chamber, so that a uniform heat distribution to the air heating chamber takes place.

5. The air heater according to claim 3, wherein the openings are formed as boreholes and/or slits.

6. The air heater according to claim 1, wherein the air heater is designed in such a manner that during operation, the expendable combustion chamber has a surface temperature in the range of 700 C. to 900C.

7. The air heater according to claim 1, wherein the air heater is designed in such a manner that during operation, the heated process air discharged from the air heater has a temperature in the range of 250 C. to 350 C.

8. A drying tower for drying a product to be dried, characterized by the air heater according to claim 1.

9. The air heater according to claim 7, wherein the heated process air discharged from the air heater has a temperature in the range of 280 C. to 320 C.

Description

[0032] In the following, the invention will be explained in more detail based on an exemplary embodiment. In the drawings:

[0033] FIG. 1 shows a highly schematic sectional representation of an air heater with an expendable combustion chamber.

[0034] An air heater 101 comprises a combustion chamber 103. A burner 105 is disposed on an upper side of the combustion chamber 103. The burner 105 is connected with a combustion air supply 119 and a combustion gas supply 121. An expendable combustion chamber 107 is disposed under the burner 105 in middle of the combustion chamber 103. The expendable combustion chamber 107 comprises a plurality of holes 109, wherein the holes 109 are distributed differently in a lower area of the expendable combustion chamber 107 than in a middle area of the expendable combustion chamber 107.

[0035] In addition, the air heater 101 comprises a process air access 113 at the bottom, which is formed in a circular circumferential manner within the air heater 101. On its upper side and its lateral walls, the air heater 103 comprises a circularly circumferential air heating chamber 111, which is formed by meander-shaped flow channels. The air heating chamber 111 ends with a process air exit 115.

[0036] In addition, the combustion chamber 103 is connected with a circularly circumferential flue gas outlet 123, which ends with a flue gas exit 117.

[0037] In the air heater 101 a combustion gas is supplied to the burner 105 by way of the combustion gas supply 121 and a combustion air is supplied to the burner by way of the combustion air supply 119 and burned, whereby a corresponding flame is formed. The expendable combustion chamber 107 surrounds the downward oriented flame in the middle and lower area of the flame. In the middle and lower area of the expendable combustion chamber 107, the generated flue gases flow through the holes 109 into the combustion chamber 103.

[0038] In the upper area of the flame the expendable chamber 107 is free of any holes, as the flame temperature is lower there than at the tip of the flame, so that by surrounding the flame with the expendable combustion chamber 107 the flame temperature is increased in that area. The expendable combustion chamber 107 has a temperature of 800 C. at its surface.

[0039] A thermal energy of the combustion generated in the combustion chamber 103 is transferred from it to the circularly circumferential air heating chamber 111. In addition, process air is continuously introduced at an ambient temperature into the air heating chamber 111 by way of the process air access 113, wherein the process air warms up while flowing through the air heating chamber 111 and leaves the process air exit 115 at a temperature of 300 C.

[0040] The flue gases generated by the combustion in the combustion chamber 103 flow through the circular circumferential flue gas outlet 123, which has contact surfaces with the air heating chamber 111, so that a thermal energy of the flue gases is transferred to the process air in the air heating chamber 111. The flue gases leave the air heater 101 by way of the flue gas exit 123.

[0041] The heated process air having a temperature of 300 C. is supplied to a drying tower for drying milk after leaving the process air exit 115 of the air heater 101.

[0042] An air heater is thus provided that ensures an optimal utilization of combustion gas and an optimal process air temperature for the subsequent drying process in the drying tower as a result of a uniform heat distribution. In addition, the emissions caused by the flue gases are reduced as a result of the targeted control of the flame by way of the expendable combustion chamber.

LIST OF REFERENCE NUMERALS

[0043] 101 Air heater

[0044] 103 Combustion chamber

[0045] 105 Burner

[0046] 107 Expendable combustion chamber

[0047] 109 Holes

[0048] 111 Air heating chamber

[0049] 113 Process air access

[0050] 115 Process air exit

[0051] 117 Flue gas exit

[0052] 119 Combustion air supply

[0053] 121 Combustion air supply

[0054] 123 Flue gas outlet