Method for drying moist material and drying plant

Abstract

A method for drying moist material includes supplying the moist material to a feeding unit of a drying plant through a supply pipe; depositing the moist material on a drying surface, while, based on a parameter that depends on the water content of the moist material passing by a sensor at least one of the supply pipe and the feeding unit, continuously regulating a quantity of the moist material being deposited on the drying surface per unit of time; and drying the moist material on the drying surface. A related drying plant dries moist material using a sensor for sensing a parameter of the moist material supplied and varying a quantity of the moist material being deposited on the drying surface per unit of time.

Claims

1. A method for drying moist material with a drying plant, the method comprising the steps of: supplying the moist material to a feeding unit of the drying plant through a supply pipe of the drying plant; depositing the moist material on a drying surface of the drying plant using the feeding unit; sensing a value of a parameter that depends on a water content of the moist material passing by a sensor proximate at least one of the supply pipe and the feeding unit; regulating a quantity of the moist material being deposited on the drying surface per unit of time only when the value of the parameter sensed in the sensing step changes by at least a minimum amount, the minimum amount being one of a first difference between the value sensed in the sensing step and a reference value in a defined period of time or a second difference between the value sensed in the sensing step and a specific minimum value; and drying the moist material on the drying surface.

2. A method according to claim 1, wherein the value of the parameter is determined at regular intervals.

3. A method according to claim 1, wherein the moist material is moved through the supply pipe towards the feeding unit, whereby a conveying capacity of the conveyor is regulated taking the parameter into account.

4. A method according to claim 1, wherein the value of the parameter is averaged over a defined period and the quantity of the moist material being deposited on the drying surface per unit of time by the feeding unit is regulated based on respective averaged parameters.

5. A method according to claim 1, wherein the parameter is determined with a non-contact microwave sensor.

6. A method according to claim 1, wherein regulation of the quantity of moist material being deposited on the drying surface per unit of time takes place based on at least one of a current drying capacity and additional characteristic values of the drying plant.

7. A method according to claim 1, wherein the feeding unit includes an extruder with a pelletization device for making pellets of moist material, whereby the pelletization device is operated taking the parameter into account.

8. A drying plant for drying moist material, the drying plant comprising: at least one drying surface to receive the moist material during drying; at least one feeding unit for depositing the moist material on the drying surface while the drying plant is operating; at least one supply pipe through which the moist material to be dried can be supplied to the feeding unit; at least one sensor arranged in at least one of the supply pipe and the feeding unit, the sensor measuring a value of a parameter that depends on a water content of the moist material passing by the sensor; and a control unit in communication with the sensor and the feeding unit, the control unit taking the parameter into account to regulate a quantity of the moist material being deposited on the drying surface by the feeding unit while the drying plant is operating only when the value of the parameter measured by the sensor changes by at least a minimum amount, the minimum amount being one of a first difference between the value sensed in the sensing step and a reference value in a defined period of time or a second difference between the value sensed in the sensing step and a specific minimum value.

9. A drying plant according to claim 8, wherein the device includes a conveyor for supplying the moist material to the feeding unit through the supply pipe while the drying plant is operating, the control unit regulating a conveying capacity of the conveyor taking the parameter into account.

10. A drying plant according to claim 9, wherein the conveyor includes a pump.

11. A drying plant according to claim 8, wherein the senses the parameter without making contact with the moist material.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further advantages of the invention are described in the following embodiment drawing, which shows schematically:

(2) FIG. 1 is a perspective view of a drying plant according to the invention.

DETAILED DESCRIPTION

(3) The only FIGURE shows a perspective view of a drying plant for moist material 1 (especially sludge) as an embodiment of a drying plant according to the invention, with which incidentally the method according to the invention can also be implemented.

(4) The drying plant comprises a drying surface 4 formed by a continuously powered drying belt 8, whereby the drying belt 8 has been executed with perforations in this example to allow drying air to pass, which is in turn blown by a heating arrangement 9 installed below the drying surface 4, for example.

(5) Apart from that, the drying plant has a feeding unit 3 along a guide 7 that can be moved back and forth with the help of a drive (not shown) used to supply the moist material 1 to be dried to the feeding unit 3 through a supply pipe 2 executed in a partially flexible way with the help of a pump 6, so it can be deposited in a controlled way on the drying surface 4.

(6) The feeding unit 3 comprises, for example, an extruder unit with a matrix and a measuring unit that can be moved relative to the matrix, with whose help the moist material 1 pressed through the matrix is broken up into individual pellet-shaped moist material units.

(7) Needless to say, the moist material 1 can also come out of the feeding unit 3 as a strand (see FIGURE) without having to be pelletized here. In this case, the feeding unit 3 is not equipped with a measuring unit.

(8) Now, to ensure that the moist material 1 is dried to a uniform drying level regardless of its water content, the drying plant provides a sensor 5 to the supply pipe 2 or feeding unit 3 with which the water content of the moist material 1 can be determined right before it is deposited on the drying surface 4. Furthermore, a control unit is provided (not shown), functioning to regulate the conveying capacity of the pump 6 depending on the water content of the moist material 1 passing by the sensor 5. Thus, in the final analysis, the quantity of moist material 1 being fed depends on the water content determined. Thus, supply is lowered when the water content is higher but can be increased when the water content is lower.

(9) By way of an example, a thick spot 10, formed when the sensor 5 temporarily detected lower water content and correspondingly increased the supply capacity in the short term is shown in the FIGURE.

(10) The present invention is not restricted to the embodiments shown and described. Variations within the framework of the patent claims are just as possible as any combination of the characteristics described, even if they are shown and described in different sections of the description or the claims or in different embodiments.