Drying system for drying moist material and method for controlling the same

Abstract

The invention relates to a method for controlling a drying plant (1), in particular a sewage sludge drying plant, for drying moist material (2), especially sewage sludge, in which the moist material (2) is fed into a drying chamber (5) of the drying plant (1) via an inlet (3) and in which the at least partially dried material (2) is discharged from the drying chamber (5) via an outlet (4). Furthermore, the amount of water evaporated per unit time during the drying of the moist material (2) is determined. In addition, the amount of moist material (2) fed into the drying plant (1) per unit time is increased or decreased, taking into account the determined amount of water evaporated per unit time. The invention also relates to the drying plant (1).

Description

[0001] The present invention relates to a method for controlling a drying plant, in particular a sewage sludge drying plant, for drying moist material, in particular sewage sludge, in which the moist material is fed into a drying chamber of the drying plant via an inlet and in which the at least partially dried material is discharged from the drying chamber via an outlet.

[0002] Furthermore, a drying plant, in particular in the form of a sewage sludge drying plant, for drying moist material, especially sewage sludge, is proposed, wherein the drying plant has a control unit for controlling the drying plant and a drying room in which the moist material is dried during operation of the drying plant, and wherein the drying room includes an inlet for the moist material and an outlet for the material dried in the drying room.

[0003] A corresponding drying system is known from JP 2002 160000 A.

[0004] The object of the present invention is to create a method or a drying system that has high efficiency and thus high drying performance.

[0005] The problem is solved by a method and / or a drying system with the features of the independent claims. Advantageous or preferred embodiments are each the subject of a corresponding dependent claim.

[0006] A method for controlling a drying plant for drying moist materials, particularly sewage sludge, is proposed. The drying plant can also be a sewage sludge drying plant, so that sewage sludge is dried as a moist material. The moist material is fed into the drying plant's drying chamber via an inlet. The drying chamber serves to dry the moist material. The at least partially dried material is discharged from the drying chamber via an outlet. To dry the moist material, the drying plant can, for example, include a heat source, particularly in the form of a heating unit. The heat source has a heating capacity upon which the rate or amount of water evaporation per unit of time depends. The heat source warms the moist material in the drying chamber, causing the water contained in the moist material to evaporate and consequently dry the moist material.The amount of water that evaporates per unit of time depends on the power of the heat source.

[0007] Additionally or alternatively, warm air can also be introduced into the drying room to dry the moist material. This allows for a simpler design of the drying system, as the warm air can be generated outside the system and then directed into the drying room.

[0008] Furthermore, the rate of water evaporation per unit time during the drying of the moist material is determined. Measuring this water evaporation provides direct feedback on drying efficiency and current system utilization. This enables precise process control. The feed rate of moist material into the drying system is adjusted based on the measured water evaporation per unit time, thereby optimizing system utilization. By controlling the feed rate of moist material based on the measured water evaporation per unit time, the drying capacity of the system can be optimally utilized. The drying capacity can, for example, be defined by the amount of moist material fed into the drying chamber per unit time.Alternatively or additionally, the drying capacity can also be defined by the amount of dried material per unit of time that is discharged from the drying room at the outlet.

[0009] Advantageously, the measured water evaporation rate per unit of time is compared with the nominal water evaporation rate per unit of time of the drying system. The nominal water evaporation rate per unit of time is a system-specific parameter that depends, for example, on the heating capacity of the drying system. This comparison serves to align the actual drying capacity of the system with its maximum drying capacity, which depends on the nominal water evaporation rate per unit of time. This prevents the drying system from operating at full capacity, as it could dry more moist material than is being fed into it. It is advantageous to adjust the amount of moist material fed into the system at the inlet based on this comparison. This control maximizes operational efficiency, as the drying system operates at or near full drying capacity.

[0010] In an advantageous embodiment of the invention, moist air generated during drying is at least partially dried by means of a condenser. The condenser removes excess moisture from the process air. As a result, the at least partially dried air can again absorb water from the moist material.

[0011] It is advantageous to measure the amount of condensate accumulating at the condenser per unit of time in order to determine the water evaporation rate. This measurement can be carried out, for example, using flow and / or level sensors, which provide a reliable basis for control.

[0012] Advantageously, in addition to or as an alternative to determining the water evaporation rate per unit of time, the relative humidity of the air entering and / or leaving the condenser is measured. This also allows the water evaporation rate per unit of time to be determined. Specifically, the difference in relative humidity between the air entering and leaving the condenser can be measured. This allows the amount of water removed from the air to be determined, from which the water evaporation rate per unit of time can be calculated.

[0013] Alternatively or additionally, it offers advantages to measure the air temperature of the air entering and / or leaving the condenser in order to determine the water evaporation rate per unit time. Determining the air temperature can be done very simply, allowing for a very easy, cost-effective, and / or reliable calculation of the water evaporation rate per unit time.

[0014] As a supplement or alternative, it is advantageous to measure the volume of air entering and / or leaving the condenser to determine the water evaporation rate per unit time. The water evaporation rate per unit time can be determined by measuring the air volume, air temperature, and / or humidity at the condenser. Specifically, this allows us to determine how much water vapor is supplied to and exiting the condenser per unit time. The difference between these values ​​can then be used to calculate the water evaporation rate per unit time.

[0015] Furthermore, it is advantageous if the change in the feed rate of moist material at the inlet occurs after a waiting period, which depends particularly on the plant size. This waiting period accounts for delays in the system and prevents adverse adjustments.

[0016] According to an advantageous embodiment of the invention, determining the water evaporation rate per unit of time and / or controlling the feed of moist material and / or the drying system is performed by a control unit. The control unit processes the acquired sensor data in real time and automatically adjusts the operating parameters, in particular the feed rate of moist material. This reduces the need for manual control and / or increases the reliability of the drying system.

[0017] Furthermore, a drying plant for drying moist material is proposed. The moist material could, for example, be sewage sludge. The drying plant could, for example, be a sewage sludge drying plant. The drying plant is preferably designed according to at least one feature of the preceding and / or following description, whereby the aforementioned features may be present individually or in any combination. The drying plant is also designed such that it can perform at least one process step of the preceding and / or following description. For this purpose, it may possess the corresponding physical features.

[0018] The drying system includes a drying chamber in which the moist material is dried during operation. The drying chamber has an inlet for the moist material and an outlet for the dried material.

[0019] The drying system can include a heat source, such as a heating unit, to dry the moist material. This heats the material, causing the water it contains to evaporate. Alternatively, or in addition, heat can be supplied to the drying system. For example, warm air can be introduced into the drying chamber to dry the moist material. Furthermore, the heat source can also include a heat pump, which heats the drying air. A condenser is mentioned below as an example, allowing the heat pump to transfer the heat generated in the condenser to the drying air.

[0020] Furthermore, the drying system includes a control unit for controlling the drying process. This control unit enables automated monitoring and / or control, thereby simplifying operation and / or reducing operating costs.

[0021] Furthermore, the control unit is designed and / or configured to increase or decrease the amount of moist material fed into the drying chamber based on a determined rate of water evaporation per unit of time during the drying process. This allows the drying system to operate at its maximum drying capacity.

[0022] It is advantageous if the control unit can control a feed unit that transports the moist material into the drying chamber during operation of the drying system. The feed unit guides the moist material into the drying chamber via the inlet. Depending on the rate of water evaporation, the feed rate can be increased or decreased. If the drying system can handle a larger volume of moist material, the feed rate is increased.

[0023] It is advantageous if the drying system has a nominal water evaporation rate per unit of time and the control unit adjusts the supply of moist material to this nominal rate during operation. This ensures that the drying system always operates at maximum efficiency and prevents underutilization.

[0024] In an advantageous embodiment of the invention, the drying system comprises a condenser for removing water from the moist air generated during operation of the drying system. Condensation is thus produced at the condenser and extracted from the moist air. The at least partially dried air can then be reused for drying the moist material and can absorb moisture again.

[0025] It is advantageous if the condenser includes a water flow sensor that can determine the amount of condensate forming on the condenser. By measuring the amount of condensate per unit of time, the water evaporation per unit of time can be determined.

[0026] It is advantageous if the water quantity sensor is a level sensor and / or a flow rate sensor. The flow rate sensor could, for example, be a magnetic-inductive flow meter. Such sensors are particularly accurate and / or require little maintenance, which increases operational reliability.

[0027] Advantageously, the drying system additionally or alternatively includes a first humidity sensor, by means of which the humidity of the air supplied to the condenser can be measured.

[0028] Alternatively or additionally, it offers advantages to include a second humidity sensor to measure the humidity of the air discharged by the condenser. Using the first and / or second humidity sensor, the amount of water collected in the condenser can be determined. This allows the rate of water evaporation to be calculated.

[0029] According to an advantageous embodiment of the invention, the drying system additionally or alternatively comprises a first temperature sensor by means of which the air temperature of the air supplied to the condenser can be measured.

[0030] Alternatively or additionally, it offers advantages to include a second temperature sensor that measures the temperature of the air discharged by the condenser. Using the first and / or second temperature sensor, the rate of water evaporation per unit of time can be calculated.

[0031] It is advantageous if the drying system additionally or alternatively includes a first air volume sensor, by means of which the amount of air supplied to the condenser can be measured.

[0032] Additionally or alternatively, a second airflow sensor is provided, which measures the volume of air discharged from the condenser. By measuring the airflow before and / or after the condenser, the amount of water that accumulates at the condenser can be determined, from which the water evaporation rate can then be calculated.

[0033] Using the described sensors—at least one humidity sensor, at least one water volume sensor, at least one air temperature sensor, and / or at least one air volume sensor—the water evaporation rate can be determined. The water volume sensor measures the amount of condensate that forms on the condenser. The water evaporation rate can also be determined by measuring the air properties, particularly the humidity, air temperature, and / or the volume of air entering and leaving the condenser.

[0034] Further advantages of the invention are described in the following exemplary embodiments. These show: Figure 1 A schematic view of a drying system with a condenser for condensing water vapor produced during drying.

[0035] Figure 1Figure 1 shows a drying plant 1 used for drying moist material 2, such as sewage sludge 2. The drying plant 1 is designed such that the moist material 2 enters a drying chamber 5 via an inlet 3. Advantageously, this inlet 3 allows for a controlled feed of the moist material 2. A feed unit 21 is located in the area of ​​the inlet 3, by means of which the moist material 2 can be conveyed into the drying chamber 5. The feed unit 21 is shown here in the exemplary form of a conveyor belt. The quantity of moist material 2 conveyed into the drying chamber 5 can also be controlled by means of the feed unit 21.

[0036] According to Figure 1 The drying room 5 includes an outlet 4 through which the at least partially dried material 2 is discharged from the drying room 5.

[0037] To transport the moist material 2 through the drying room 5 or from the inlet 3 to the outlet 4, a conveying unit 22 is arranged in the drying room 5.

[0038] A heating unit 19 is also located in the drying chamber 5, which can be used to heat the moist material 2. This heating unit 19 supplies the necessary heat energy to evaporate the water in the moist material 2. This produces water vapor 6, which can be collected by means of an exhaust hood 20. In addition to or as an alternative to the heating unit 19, warm air can also be introduced into the drying chamber 5 to heat the moist material 2. The heating unit 19 can, for example, be a heat exchanger coupled to a heat pump.

[0039] The drying system 1 also has a condenser 7, which removes water from the moist air produced during the drying process. The condenser 7 dehumidifies the air, increasing the efficiency of the drying process. Condensation 8 collects at the condenser 7 and can be drained away via a drain line 10. Water vapor 6 is supplied to the condenser 7 via at least one line 9. The air dried by the condenser 7 can then be returned to the drying chamber 5 via another line 9, allowing the dried air to reabsorb the water vapor 6. The heat generated at the condenser 7 can, for example, be transferred by the heat pump to the heating unit 19 to heat the moist material 2.

[0040] According to Figure 1A water quantity sensor 12 is arranged in the condenser 7. This water quantity sensor 12 determines the amount of condensate 8 forming at the condenser 7 and thus allows conclusions to be drawn about the water evaporation per unit of time during the drying process. The use of a level and / or flow rate sensor as the water quantity sensor 12 is particularly advantageous. The flow rate sensor can preferably be designed as a magnetic-inductive flow meter. The drying system 1 can be optimally controlled by the precise measurement of the condensate quantity.

[0041] Additionally or alternatively, the drying system 1 can be configured according to the embodiment shown here. Figure 1The system comprises a first humidity sensor 13 and / or a second humidity sensor 14. The first humidity sensor 13 measures the humidity of the air supplied to the condenser 7, while the second humidity sensor 14 measures the humidity of the air discharged from the condenser 7. The first and / or second humidity sensor 13, 14 enable an accurate determination of the water evaporation per unit of time.

[0042] In a further embodiment, the drying system 1 of the present embodiment has according to Figure 1 A first temperature sensor 15 and / or a second temperature sensor 16 are installed. The first temperature sensor 15 measures the air temperature of the air supplied to the condenser 7, while the second temperature sensor 16 records the air temperature of the exhaust air. These temperature measurements enable the determination of the water evaporation per unit of time.

[0043] To measure the amount of air supplied to or discharged from the condenser 7, the drying system 1 of the embodiment shown here can additionally or alternatively include a first air volume sensor 17 and / or a second air volume sensor 18. The first air volume sensor 17 enables the measurement of the amount of air supplied to the condenser 7. The second air volume sensor 18 can measure the amount of air discharged from the condenser 7.

[0044] The rate of water evaporation per unit time can be determined using at least one or more of the sensors 13, 14, 15, 16, 17, 18 mentioned here. This rate is determined by the aforementioned sensors 13, 14, 15, 16, 17, 18 based on the condition of the air supplied to and / or discharged from condenser 7. Additionally or alternatively, the rate of water evaporation per unit time can also be determined using the water volume sensor 12, which measures the amount of condensate 8. The sensors 13, 14, 15, 16, 17, 18 described here can, as shown, be assigned to the lines 9 leading to and from condenser 7.

[0045] The drying system 1 also includes a control unit 11. The control unit 11 can determine the water evaporation rate per unit of time using at least one or more of the sensors 12, 13, 14, 15, 16, 17, 18. The water volume sensor 12, the first humidity sensor 13, the second humidity sensor 14, the first temperature sensor 15, the second temperature sensor 16, the first air volume sensor 17, and / or the second air volume sensor 18 can be connected to the control unit 11 to transmit the corresponding measured values. The control unit 11 can then determine the water evaporation rate per unit of time. Furthermore, the control unit 11 can have access to a nominal water evaporation rate per unit of time for the drying system 1, for example, stored in a memory. The nominal water evaporation rate per unit of time depends on the drying system 1 and is a system-specific parameter.For example, the nominal water evaporation rate per unit of time of the drying system 1 depends on the maximum heating power of the heating unit 19. The higher the heating power of the heating unit 19, the greater the nominal water evaporation rate per unit of time.

[0046] Furthermore, the control unit 11 can compare the measured water evaporation rate per unit of time with the nominal water evaporation rate per unit of time of the drying system 1 and increase or decrease the supply of moist material 2 to the drying chamber 5. This allows the drying system 1 to operate in an optimal state. This maximizes the amount of moist material 2 dried by the drying system 1.

[0047] The control unit 11 controls the feed unit 21, which conveys the moist material 2 through the inlet 3 into the drying chamber 5. By controlling the feed rate per unit of time, the control unit 11 ensures optimal utilization of the drying system 1. If the water evaporation rate per unit of time falls below the nominal rate, the feed rate is increased. This allows the drying system 1 to operate at maximum drying capacity. Reference symbol list

[0048] 1 Drying system 2 Moist material / sewage sludge 3 Inlet 4 Outlet 5 Drying chamber 6 Water vapor 7 Condenser 8 Condensed water 9 Pipes 10 Drain pipe 11 Control unit 12 Water volume sensor 13 First humidity sensor 14 Second humidity sensor 15 First temperature sensor 16 Second temperature sensor 17 First air volume sensor 18 Second air volume sensor 19 Heating unit 20 Extractor hood 21 Feed unit 22 Conveyor unit

Claims

1. Method for controlling a drying plant (1), in particular a sewage sludge drying plant, for drying moist material (2), in particular sewage sludge, in which the moist material (2) is fed into a drying room (5) of the drying plant (1) via an inlet (3) and in which the at least partially dried material (2) is discharged from the drying room (5) via an outlet (4), characterized by that a water evaporation per unit of time occurring during the drying of the moist material (2) is determined, and that a quantity of moist material (2) supplied to the drying system (1) per unit of time is increased or decreased, taking into account the determined water evaporation per unit of time.

2. Method according to the previous claim, characterized by thatthe determined water evaporation per time is compared with a nominal water evaporation per time of the drying system (1), and taking the comparison into account the feed quantity of moist material (2) at the inlet (3) is increased or decreased.

3. Method according to one or more of the preceding claims, characterized by that moist air produced during drying is at least partially dried by means of a condenser (7).

4. Method according to one or more of the preceding claims, characterized by thatto determine the water evaporation per time, a quantity of condensate (8) accumulating at the condenser (7) is measured per time, and / or to determine the water evaporation per time, the humidity of the air supplied to and / or leaving the condenser (7) is measured, and / or to determine the water evaporation per time, the air temperature of the air supplied to and / or leaving the condenser (7) is measured.

5. Method according to one or more of the preceding claims, characterized by that To determine the water evaporation per unit of time, a quantity of air is measured that is supplied to the condenser (7) and / or that leaves the condenser (7).

6. Method according to one or more of the preceding claims, characterized by that the change in the quantity of moist material supplied (2) at the inlet (3) takes place after a waiting period, which depends in particular on the size of the plant.

7. Method according to one or more of the preceding claims, characterized by that the determination of the water evaporation per unit of time and / or the control of the supply of moist material (2) and / or the control of the drying system (1) is carried out by a control unit (11).

8. Drying plant (1), in particular in the form of a sewage sludge drying plant, for drying moist material (2), in particular sewage sludge, wherein the drying plant (1) is preferably configured to carry out the method according to at least one of the preceding claims, comprising a drying chamber (5) in which the moist material (2) is dried during operation of the drying plant (1) and wherein the drying chamber (5) comprises an inlet (3) for the moist material (2) and an outlet (4) for the material (2) dried in the drying chamber (5), and comprising a control unit (11) for controlling the drying plant (1). characterized by thatthe control unit (11) is designed and / or configured in such a way that it can increase or decrease the quantity of moist material (2) supplied to the drying chamber (5) based on a determined water evaporation rate per unit of time during the drying of the moist material (2).

9. Drying plant according to the previous claim, characterized by that the control unit (11) can control a feed unit (21) by means of which the moist material (2) is transported into the drying room (5) during the operation of the drying system (1).

10. Drying system according to claim 8 or 9, characterized by that the drying system (1) has a nominal water evaporation rate per time and the control unit (11) adjusts the supply of moist material (2) to the nominal water evaporation rate per time during operation of the drying system (1).

11. Drying system according to one or more of the preceding claims 8 to 10, characterized by thatThe drying system (1) includes a condenser (7) for removing water from moist air generated during the operation of the drying system (1).

12. Drying system according to one or more of the preceding claims 8 to 11, characterized by that the condenser (7) comprises a water quantity sensor (12) by means of which a quantity of condensate (8) accumulating at the condenser (7) can be determined, wherein the water quantity sensor (12) is preferably a level sensor and / or a flow rate sensor, in particular a magnetic-inductive flow meter.

13. Drying system according to one or more of the preceding claims 8 to 12, characterized by thatthe drying system (1) includes a first humidity sensor (13) by means of which the humidity of the air supplied to the condenser (7) can be measured, and / or that the drying system (1) includes a second humidity sensor (14) by means of which the humidity of the air discharged from the condenser (7) can be measured.

14. Drying system according to one or more of the preceding claims 8 to 13, characterized by that the drying system (1) includes a first temperature sensor (15) by means of which the air temperature of the air supplied to the condenser (7) can be measured, and / or that the drying system (1) includes a second temperature sensor (16) by means of which the air temperature of the air discharged from the condenser (7) can be measured.

15. Drying system according to one or more of the preceding claims 8 to 14, characterized by thatthe drying system (1) includes a first air volume sensor (17) by means of which the volume of air supplied to the condenser (7) can be measured, and / or that the drying system (1) includes a second air volume sensor (18) by means of which the volume of air discharged from the condenser (7) can be measured.

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