Multi-stage sludge drying system and drying method

Abstract

The invention discloses a multi-stage sludge drying system which comprises a feeding unit, a multi-stage series drying unit, a heat exchange circulating unit, a moisture removal unit and a discharging unit, the multi-stage series drying unit comprises a low-temperature preheating module, a medium-temperature evaporation module and a high-temperature shaping module which are arranged in sequence, and the heat exchange circulation unit is communicated with all the modules in the multi-stage series drying unit and provides heat media in different temperature intervals for all the modules; the moisture removal unit is respectively communicated with each module in the multi-stage series drying unit, and is used for collecting and discharging moisture in each module; the system further comprises a control unit, the control unit is in signal connection with the feeding unit, the multi-stage series drying unit, the heat exchange circulating unit, the moisture removal unit and the discharging unit, and the sludge conveying speed, the thermal medium parameters and the moisture removal amount are controlled based on the obtained working conditions of all the units. Compared with the prior art, the multi-section type sludge drying system and the drying method have the advantages that the multi-section type sludge drying system and the drying method which are used for performing sectional gradient heating according to the sludge drying characteristics are provided.

Description

Technical Field

[0001] This invention relates to the field of sludge waste treatment technology, specifically to a multi-stage sludge drying system and drying method. Background Technology

[0002] Sludge is a major byproduct of wastewater treatment, characterized by high water content, high viscosity, easy putrefaction, and the presence of pathogens. Drying is a key pretreatment step for sludge reduction, stabilization, and resource recovery.

[0003] Existing sludge drying technologies often use a single high-temperature heat source, resulting in heat waste during the low-temperature preheating stage. Furthermore, the rapid evaporation of water at high temperatures carries away a large amount of latent heat without effective recovery. Due to the lack of segmented and precise temperature control, it is difficult to take into account the changes in the physicochemical properties of sludge at different moisture content stages.

[0004] The discharged hot and humid gases are usually discharged directly or after simple treatment, and the large amount of sensible and latent heat contained in them is not recovered and utilized, resulting in energy waste. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the above-mentioned technical defects and provide a multi-stage sludge drying system and drying method that uses segmented gradient heating based on the sludge drying characteristics.

[0006] To solve the above-mentioned technical problems, the technical solution provided by the present invention is: a multi-stage sludge drying system, including a feeding unit, a multi-stage series drying unit, a heat exchange circulation unit, a dehumidification unit and a discharge unit;

[0007] The multi-stage series drying unit includes a low-temperature preheating module, a medium-temperature evaporation module, and a high-temperature shaping module arranged in sequence. The heat exchange circulation unit is connected to each module in the multi-stage series drying unit and provides heat medium with different temperature ranges to each module.

[0008] The dehumidification unit is connected to each module in the multi-stage series drying unit, and collects and discharges the moisture in each module.

[0009] It also includes a control unit, which is connected to the feeding unit, the multi-stage series drying unit, the heat exchange circulation unit, the dehumidification unit, and the discharge unit respectively, and controls the sludge conveying speed, heat medium parameters and dehumidification volume based on the acquired operating conditions of each unit.

[0010] Preferably, the low-temperature preheating module, the medium-temperature evaporation module, and the high-temperature shaping module are each equipped with an independent stirring and conveying mechanism, including a drive motor, a transmission shaft, and irregularly shaped stirring blades distributed along the axial direction.

[0011] The pitch or inclination angle of the irregularly shaped stirring blades is gradually set along the sludge flow direction.

[0012] Preferably, the feeding unit includes a sludge receiving hopper, a crushing and equalizing device, and a quantitative feeder arranged in sequence;

[0013] The crushing and homogenizing device shears, crushes, mixes, and homogenizes the sludge, and the quantitative feeder delivers the homogenized sludge to the low-temperature preheating module at a set flow rate.

[0014] Preferably, the heat exchange cycle unit includes at least two independent heat medium generating devices and a heat medium mixing and regulating device;

[0015] The two heat medium generating devices respectively generate a low-temperature range heat medium and a high-temperature range heat medium. The heat medium mixing and mixing device mixes heat media of different temperatures in proportion according to the instructions of the control unit to generate a medium-temperature range heat medium.

[0016] Preferably, the heat exchange circulation unit further includes a circulation pump group, which controls the flow of the heat medium to each module and circulates in a loop.

[0017] Preferably, the dehumidification unit includes a dehumidification port that is respectively connected to the low-temperature preheating module, the medium-temperature evaporation module and the high-temperature shaping module, a collection pipe connected to the multiple dehumidification ports and a heat recovery mechanism;

[0018] The heat recovery mechanism collects the hot and humid gas discharged from each module and extracts the sensible heat and latent heat.

[0019] Preferably, the discharge unit includes a cooling chamber and a sealed discharge valve;

[0020] The cooling chamber receives dried sludge from the high-temperature shaping module and reduces the sludge temperature to a safe storage temperature through heat exchange.

[0021] The sealed discharge valve intermittently discharges the cooled, dried sludge to the outside of the system.

[0022] Another aspect of the present invention discloses a drying method for a multi-stage sludge drying system, comprising the following steps:

[0023] S1: Transports the heat medium within the corresponding temperature range to bring the internal temperature of each module to the preset process standby value;

[0024] S2: The dried sludge enters the feeding unit, is sheared, crushed and mixed by the crushing and homogenizing device, and is then continuously and evenly fed into the low-temperature preheating module according to the initial flow rate.

[0025] S3: Segmented gradient drying process;

[0026] S4: The dehumidification unit collects the humid heat gas generated by each module, and extracts sensible heat and latent heat through the heat recovery mechanism;

[0027] S5: The dried sludge is discharged from the end of the high-temperature shaping module and enters the cooling chamber of the discharge unit for cooling treatment. After the sludge temperature drops to the safe storage temperature, it is discharged from the system intermittently or continuously through the sealed discharge valve.

[0028] Preferably, in S5, the control unit dynamically adjusts the flow rate and residence time of the cooling medium in the cooling chamber based on feedback data from the discharge temperature sensor.

[0029] The advantages of this invention compared to the prior art are:

[0030] This invention uses a three-stage gradient heating system of low temperature, medium temperature and high temperature to match the drying characteristics of sludge at different stages, thereby avoiding energy waste and significantly improving thermal efficiency.

[0031] The invention's independent heat medium distribution system, combined with intelligent control, achieves precise temperature control of each drying section, while the integrated heat recovery mechanism makes full use of the sensible and latent heat in the exhaust gas, further reducing system energy consumption. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of a multi-stage sludge drying system. Detailed Implementation

[0033] The present invention will now be described in further detail with reference to the accompanying drawings.

[0034] Combined with appendix Figure 1 The multi-stage sludge drying system shown includes a feeding unit, a multi-stage series drying unit, a heat exchange and circulation unit, a dehumidification unit, a discharge unit, and a central control unit.

[0035] The multi-stage series drying unit includes a low-temperature preheating module, a medium-temperature evaporation module, and a high-temperature shaping module arranged in sequence. The heat exchange circulation unit is connected to each module in the multi-stage series drying unit and provides heat medium with different temperature ranges to each module. The dehumidification unit is connected to each module in the multi-stage series drying unit and collects and discharges the moisture in each module.

[0036] The control unit controls the sludge conveying speed, heat medium parameters, and moisture discharge rate based on the acquired operating conditions of each unit.

[0037] In one embodiment:

[0038] The low-temperature preheating module, the medium-temperature evaporation module, and the high-temperature shaping module are all equipped with independent stirring and conveying mechanisms, including a drive motor, a transmission shaft, and irregularly shaped stirring blades distributed along the axial direction; the pitch or inclination angle of the irregularly shaped stirring blades is gradually set along the sludge flow direction, and the feeding unit includes a sludge receiving hopper, a crushing and equalizing device, and a quantitative feeder arranged in sequence.

[0039] The crushing and homogenizing device shears, crushes, mixes, and homogenizes the sludge, and the quantitative feeder delivers the homogenized sludge to the low-temperature preheating module at a set flow rate.

[0040] In one embodiment:

[0041] The heat exchange cycle unit includes at least two independent heat medium generating devices and a heat medium mixing and regulating device;

[0042] The two heat medium generating devices respectively generate heat medium in the low temperature range and heat medium in the high temperature range. The heat medium mixing and mixing device mixes heat medium of different temperatures in proportion according to the instructions of the control unit to generate heat medium in the medium temperature range. The heat exchange circulation unit also includes a circulation pump group, which controls the flow of heat medium to each module and circulates in a loop.

[0043] In use, the dehumidification unit includes a dehumidification port that is connected to the low-temperature preheating module, the medium-temperature evaporation module and the high-temperature shaping module respectively, a collection pipe connected to the multiple dehumidification ports and a heat recovery mechanism.

[0044] The heat recovery mechanism collects the hot and humid gas discharged from each module and extracts the sensible heat and latent heat.

[0045] In one embodiment:

[0046] The discharge unit includes a cooling chamber and a sealed discharge valve;

[0047] The cooling chamber receives dried sludge from the high-temperature shaping module and reduces the sludge temperature to a safe storage temperature through heat exchange.

[0048] The sealed discharge valve intermittently discharges the cooled, dried sludge to the outside of the system.

[0049] In specific implementation of the present invention,

[0050] The sludge first enters the feeding unit, where a sludge receiving hopper temporarily stores the wet sludge. It then enters the crushing and homogenizing device, which uses a high-speed rotating cutter shaft to shear and crush the sludge, breaking up large clumps and mixing them uniformly to ensure consistent material properties. The treated sludge is then precisely metered by a quantitative feeder and delivered at a constant flow rate to the inlet of the multi-stage series drying unit. In the low-temperature preheating module of the multi-stage series drying unit, the blade pitch is larger to accommodate the large volume of sludge with high moisture content. As the sludge flows forward, its moisture content decreases and its volume shrinks, with the blade pitch of subsequent modules gradually decreasing to ensure continuous and effective thrust and tumbling. This design significantly reduces the possibility of sludge adhering to the cylinder wall and prevents uneven drying caused by localized accumulation.

[0051] The heat exchange circulation unit provides customized heat sources for each module, including two heat medium generating devices: one generates a low-temperature heat medium, and the other generates a high-temperature heat medium.

[0052] The low-temperature preheating module introduces a low-temperature heat medium to gently raise the temperature of the sludge and prevent the surface from hardening too quickly;

[0053] The medium-temperature evaporation module is fed with a medium-temperature heat medium, which provides a large amount of latent heat of vaporization and efficiently removes moisture.

[0054] The high-temperature shaping module is circulated with a high-temperature heat medium to deeply remove bound water and complete particle shaping.

[0055] The circulating pump unit drives the heat medium to circulate in a closed loop, ensuring a continuous and stable supply of heat.

[0056] The dehumidification unit collects the humid heat gas generated by evaporation through the dehumidification port at the top of each module and collects it into the collection pipe. The gas passes through the heat recovery mechanism, which extracts the sensible heat and latent heat from the waste gas and re-injects the recovered energy into the heat exchange cycle unit or uses it for other purposes.

[0057] During use, the dried sludge is discharged from the end of the high-temperature shaping module. At this time, the temperature is high, and the sludge then enters the cooling chamber of the discharge unit.

[0058] The cooling chamber is equipped with a cooling jacket or circulates cold air to rapidly reduce the sludge temperature to below 40°C through heat exchange. The control unit monitors the discharge temperature sensor data in real time and dynamically adjusts the flow rate of the cooling medium and the residence time of the sludge in the cooling chamber to ensure the cooling effect. Finally, the cooled dry sludge is discharged intermittently or continuously through a sealed discharge valve into the finished product silo. The entire discharge process remains sealed, preventing dust from flying.

[0059] The control unit collects real-time data on temperature, pressure, motor current, exhaust humidity, and discharge moisture content from each module. Based on this data, it also includes adjustments and controls.

[0060] Adjust the speed of the quantitative feeder to change the sludge processing capacity;

[0061] Adjust the valve opening of the heat medium mixing and blending device to precisely control the temperature of the heat medium in each module;

[0062] Adjust the frequency of the circulating pump set and optimize the flow rate of the heat medium;

[0063] Adjust the airflow of the dehumidifier fan to balance the slight negative pressure inside the chamber;

[0064] Adjust the operating conditions of the cooling chamber based on the feedback of the discharge temperature.

[0065] The contents not described in detail in this specification are existing technologies known to those skilled in the art.

[0066] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0067] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention; the actual structure is not limited thereto. In conclusion, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the invention, such designs should fall within the protection scope of the present invention.

Claims

1. A multi-stage sludge drying system, characterized in that: It includes a feeding unit, a multi-stage series drying unit, a heat exchange circulation unit, a dehumidification unit, and a discharge unit; The multi-stage series drying unit includes a low-temperature preheating module, a medium-temperature evaporation module, and a high-temperature shaping module arranged in sequence. The heat exchange circulation unit is connected to each module in the multi-stage series drying unit and provides heat medium with different temperature ranges to each module. The dehumidification unit is connected to each module in the multi-stage series drying unit, and collects and discharges the moisture in each module. It also includes a control unit, which is connected to the feeding unit, the multi-stage series drying unit, the heat exchange circulation unit, the dehumidification unit, and the discharge unit respectively, and controls the sludge conveying speed, heat medium parameters and dehumidification volume based on the acquired operating conditions of each unit.

2. The multi-stage sludge drying system according to claim 1, characterized in that: The low-temperature preheating module, the medium-temperature evaporation module, and the high-temperature shaping module are all equipped with independent stirring and conveying mechanisms, including a drive motor, a transmission shaft, and irregularly shaped stirring blades distributed along the axial direction. The pitch or inclination angle of the irregularly shaped stirring blades is gradually set along the sludge flow direction.

3. The multi-stage sludge drying system according to claim 2, characterized in that: The feeding unit includes a sludge receiving hopper, a crushing and equalizing device, and a quantitative feeder arranged in sequence. The crushing and homogenizing device shears, crushes, mixes, and homogenizes the sludge, and the quantitative feeder delivers the homogenized sludge to the low-temperature preheating module at a set flow rate.

4. The multi-stage sludge drying system according to claim 1, characterized in that: The heat exchange cycle unit includes at least two independent heat medium generating devices and a heat medium mixing and regulating device; The two heat medium generating devices respectively generate a low-temperature range heat medium and a high-temperature range heat medium. The heat medium mixing and mixing device mixes heat media of different temperatures in proportion according to the instructions of the control unit to generate a medium-temperature range heat medium.

5. A multi-stage sludge drying system according to claim 4, characterized in that: The heat exchange circulation unit also includes a circulation pump group, which controls the flow of the heat medium to each module and circulates in a loop.

6. The multi-stage sludge drying system according to claim 1, characterized in that: The dehumidification unit includes a dehumidification port that is connected to the low-temperature preheating module, the medium-temperature evaporation module and the high-temperature shaping module respectively, a collection pipe connected to the multiple dehumidification ports and a heat recovery mechanism. The heat recovery mechanism collects the hot and humid gas discharged from each module and extracts the sensible heat and latent heat.

7. The multi-stage sludge drying system according to claim 1, characterized in that: The discharge unit includes a cooling chamber and a sealed discharge valve; The cooling chamber receives dried sludge from the high-temperature shaping module and reduces the sludge temperature to a safe storage temperature through heat exchange. The sealed discharge valve intermittently discharges the cooled, dried sludge to the outside of the system.

8. A drying method for a multi-stage sludge drying system according to any one of claims 1 to 7, characterized in that: Includes the following steps: S1: Transports the heat medium within the corresponding temperature range to bring the internal temperature of each module to the preset process standby value; S2: The dried sludge enters the feeding unit, is sheared, crushed and mixed by the crushing and homogenizing device, and is then continuously and evenly fed into the low-temperature preheating module according to the initial flow rate. S3: Segmented gradient drying process; S4: The dehumidification unit collects the humid heat gas generated by each module, and extracts sensible heat and latent heat through the heat recovery mechanism; S5: The dried sludge is discharged from the end of the high-temperature shaping module and enters the cooling chamber of the discharge unit for cooling treatment. After the sludge temperature drops to the safe storage temperature, it is discharged from the system intermittently or continuously through the sealed discharge valve.

9. The drying method of a multi-stage sludge drying system according to claim 8, characterized in that: The control unit in S5 dynamically adjusts the flow rate and residence time of the cooling medium in the cooling chamber based on feedback data from the discharge temperature sensor.

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