Environment-friendly municipal sludge drying system and method

Abstract

The application discloses an environment-friendly municipal sludge drying system, and belongs to the sludge treatment process field, which is suitable for drying treatment of municipal sludge. The drying system comprises a hot blast furnace, a heat exchanger, a condenser, a collector, a dryer and a waste gas treatment device, and can further comprise a high-temperature mixing chamber. The dryer adopts a gas drying mode, a material inlet of the dryer receives treated wet sludge, a gas source inlet receives high-temperature drying wind, and the high-temperature drying wind is used for drying treatment of the wet sludge. A material inlet of the collector is connected with a dried material outlet of the dryer, dried products are collected, and low-temperature wet wind is discharged. The condenser condenses the low-temperature wet wind to obtain condensed water and low-temperature drying wind. The heat exchanger exchanges heat between high-temperature hot wind and low-temperature drying wind to obtain waste gas and high-temperature drying wind. The hot blast furnace is connected with cold wind and heated to provide high-temperature hot wind for the heat exchanger. The sludge drying system has the advantages of high drying efficiency, stable and safe operation, energy saving and environmental protection, cost saving and the like.

Description

Technical Field

[0001] This invention belongs to the field of solid waste treatment technology, and specifically relates to an environmentally friendly municipal sludge drying system and method. Background Technology

[0002] In the treatment of municipal sewage sludge, reducing the sludge moisture content is a core task, as excessive moisture content leads to the release of large amounts of toxic and harmful substances. Generally, the moisture content of the sludge needs to be reduced to below 50% to meet landfill requirements. Existing technologies primarily adhere to the principles of material reduction, stabilization, harmlessness, and resource recovery in municipal sewage sludge treatment. However, sludge treatment is a high-energy-consuming and high-investment process, resulting in high treatment costs, which restricts the development of sludge treatment. Therefore, how to further optimize sludge drying technology, reduce process costs, and improve the comprehensive utilization level of the products remains a problem that needs to be solved. Summary of the Invention

[0003] In order to overcome the shortcomings of the prior art, the present invention aims to provide an environmentally friendly municipal sludge drying system and method, so as to reduce the energy consumption of sludge drying and improve the drying efficiency.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] An environmentally friendly municipal sludge drying system includes:

[0006] The dryer uses a gas drying method. Its material inlet receives the wet sludge to be processed, and the gas source inlet is connected to high-temperature drying air. The high-temperature drying air is used to dry the wet sludge.

[0007] The collector has its material inlet connected to the dry material outlet of the dryer, collects the dried product, and discharges low-temperature, humid air.

[0008] A condenser condenses the low-temperature, humid air to obtain condensate and low-temperature, dry air;

[0009] A heat exchanger is used to exchange heat between high-temperature hot air and low-temperature dry air to obtain exhaust gas and high-temperature dry air.

[0010] A hot air furnace is used to introduce and heat cold air to provide the high-temperature hot air to the heat exchanger.

[0011] In one embodiment, the drying system of the present invention further includes: a high-temperature mixing chamber; the high-temperature mixing chamber is located after the hot air furnace, and fully mixes the system leakage air and the hot air of the hot air furnace to obtain mixed hot air, the mixed hot air providing high-temperature hot air to the heat exchanger; the system leakage air is a diversion air of low-temperature drying air, a part of the low-temperature drying air enters the heat exchanger, and the other part enters the high-temperature mixing chamber as diversion air.

[0012] In one embodiment, the high-temperature mixing chamber, heat exchanger, dryer, collector, and condenser are connected by multiple sections of pipe to form a circulation system, and air enters each device sequentially to form circulating air.

[0013] In one embodiment, the hot air outlet of the high-temperature mixing chamber is connected to the hot air inlet of the heat exchanger through a duct, the high-temperature drying air outlet of the heat exchanger is connected to the hot air inlet of the dryer through a duct, the system air leakage outlet of the condenser is connected to the system air leakage inlet of the high-temperature mixing chamber through a duct, and supplementary air is introduced at the hot air furnace.

[0014] In one embodiment, the waste gas treatment device is connected to the waste gas outlet of the heat exchanger via a connecting pipe, and the waste gas treatment device purifies the polluted waste gas discharged from the waste gas outlet of the heat exchanger.

[0015] In one embodiment, the heat exchanger includes a high-temperature hot air inlet, a low-temperature dry air inlet, a high-temperature dry air outlet, and an exhaust gas outlet. The high-temperature hot air heats the low-temperature dry air to obtain high-temperature dry air, and the high-temperature hot air and the low-temperature dry air do not come into direct contact, but only transfer heat energy.

[0016] In one embodiment, the collector is a cyclone separator, which utilizes the rotational motion of the airflow and the difference in settling velocity of different material particle sizes to separate the dried product from the low-temperature humid air.

[0017] This invention also provides an environmentally friendly municipal sludge drying method, based on an environmentally friendly municipal sludge drying system, the process of which is as follows:

[0018] The wet sludge to be treated is sent into a dryer and dried using high-temperature drying air. During the drying process, the sludge absorbs heat and undergoes a phase change, entering the drying air as steam. The hot air is cooled down by heat absorption, forming low-temperature humid air.

[0019] The dried product and the low-temperature humid air are fed into a collector, where the dried product is collected and the low-temperature humid air is discharged.

[0020] The low-temperature, humid air is sent into a condenser for dehumidification to obtain low-temperature, dry air.

[0021] A hot air furnace is used to heat cold air to obtain high-temperature hot air;

[0022] Low-temperature drying air and high-temperature hot air are exchanged through a heat exchanger to obtain high-temperature drying air, which is then returned to the dryer.

[0023] In one embodiment, the low-temperature drying air is divided into two parts. One part enters the heat exchanger, and the other part, as a diversion air or system leakage air, enters the high-temperature mixing chamber and mixes with the high-temperature hot air to obtain the final high-temperature hot air. The final high-temperature hot air replaces the high-temperature hot air of the hot air furnace and enters the heat exchanger.

[0024] In this invention, the moisture content of the wet sludge is 70% to 80%, the moisture content of the dried product is reduced to 8% to 12%, the temperature range of the high-temperature drying air is 200℃ to 850℃, the temperature of the low-temperature humid air is 70℃ to 80℃ with a moisture content of 30% to 40%, the temperature range of the low-temperature drying air is 50℃ to 70℃, and the temperature range of the high-temperature hot air is 350℃ to 850℃.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] 1) The circulating air system adopted by the system is highly efficient and low in energy consumption, which enables the circulating air to be reused repeatedly, avoiding the waste of heat energy and following the principle of energy conservation and environmental protection.

[0027] 2) The high-temperature mixing chamber can collect leaked air for reuse, thus realizing the recycling of energy.

[0028] 3) The system equipment forms a closed loop, with a simple and compact structure. The high-temperature hot air supplied by the hot air furnace is gathered by two-stage equipment and then input into the dryer, making full use of the hot air, improving drying efficiency and drying effect, and enabling the system to operate stably and continuously.

[0029] In summary, this invention has many advantages and practical value. It has made significant improvements in both structure and function, achieved remarkable technological progress, and has great practical value. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the structure of Embodiment 1 of the present invention. Detailed Implementation

[0031] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings and examples.

[0032] To improve the drying efficiency of wet sludge, this invention adopts a circulating air system configuration and proposes a new drying system that is energy-saving and has a high drying efficiency.

[0033] refer to Figure 1 As shown in the embodiments of the present invention, the environmentally friendly municipal sludge drying system mainly includes a dryer, a collector, a condenser, a heat exchanger, and a hot air furnace.

[0034] The dryer employs a gas drying method to dry moist sludge. It has a material inlet, an air source inlet, and a dried material outlet. The material inlet receives the moist sludge to be processed, while the air source inlet receives high-temperature drying air to dry the sludge. For example, the temperature range of the high-temperature drying air output from the heat exchanger is generally around 200℃ to 850℃, the temperature range of the exhaust gas output from the heat exchanger is generally 110℃ to 120℃, and the moisture content of the moist sludge is generally 70% to 80%.

[0035] The collector is used to collect the dried material obtained from the dryer. It has a material inlet, a material outlet, and an exhaust vent. The material inlet connects to the dried material outlet of the dryer. The material, after being dried by the dryer, enters the collector along with the air and is separated. The solid, which is the dried finished product, can be collected and discharged from the material outlet. The gas, which is low-temperature, humid air, is discharged from the exhaust vent. For example, the moisture content of the dried finished product is generally around 10%, and the temperature range of the low-temperature, humid air is generally around 70℃ to 80℃, with a moisture content generally between 30% and 40%.

[0036] The condenser is used to condense the low-temperature, humid air to obtain condensate and low-temperature dry air. It has a cooling medium, an air inlet, an air outlet, and a water outlet. The air inlet receives the air from the condenser's exhaust outlet, the low-temperature, humid air is condensed using the cooling medium, the condensate is discharged from the water outlet, and the low-temperature dry air is discharged from the exhaust outlet.

[0037] For example, the temperature range of low-temperature drying air is generally around 60°C, and it generally does not contain water.

[0038] The heat exchanger is used to heat low-temperature drying air to obtain high-temperature drying air. It has a high-temperature hot air inlet, a low-temperature drying air inlet, a high-temperature drying air outlet, and an exhaust gas outlet. The high-temperature hot air inlet connects to high-temperature hot air, the low-temperature drying air inlet connects to the condenser's exhaust port, the high-temperature drying air outlet connects to the dryer's air source inlet, and the exhaust gas outlet discharges exhaust gas. In the heat exchanger, low-temperature drying air and high-temperature hot air exchange heat, using the heat from the high-temperature hot air to heat the low-temperature drying air to obtain high-temperature drying air. The heated high-temperature hot air then becomes exhaust gas. During the process, the high-temperature hot air and low-temperature drying air do not directly contact each other; only heat energy is transferred. The low-temperature drying air containing harmful pollutants can be recycled within the system, preventing pollutant accumulation and reducing the generation of new harmful pollutants. For example, the temperature range of the high-temperature hot air is generally 350℃ to 850℃, and it generally does not contain water.

[0039] A hot air furnace is used to supply high-temperature hot air to the heat exchanger and has a cold air inlet and a high-temperature hot air outlet. It has a built-in heat source that heats the incoming cold air to obtain high-temperature hot air. The hot air furnace heats the air (i.e., the cold air) within the gas passage, causing the air to absorb heat and increase its temperature.

[0040] According to the drying system of the present invention, the high-temperature drying air output from the heat exchanger is returned to the dryer as circulating hot air, providing a supplementary heat source for drying. It can fully utilize the waste heat generated during the drying process and reuse it in the drying system, forming a closed-loop airflow path, thus creating a self-circulating system. Therefore, it can continuously and stably process municipal sludge. During operation, it can efficiently utilize hot air to form a circulating airflow path, greatly reducing energy consumption and making it more environmentally friendly. It has significant advantages such as high drying efficiency, stable and safe operation, energy saving, environmental protection, and cost savings.

[0041] In a further embodiment of the invention, the sludge drying system further includes a high-temperature mixing chamber. The high-temperature mixing chamber is located after the hot air furnace and has a hot air inlet or supplementary air inlet, a system leakage air inlet, and a hot air outlet. Its main function is to thoroughly mix the system leakage air and the hot air from the hot air furnace to obtain mixed hot air, which is then used as high-temperature hot air supplied to the heat exchanger, thus replacing the method of directly using the hot air from the hot air furnace. In this invention, the system leakage air is a portion of the low-temperature drying air diverted into the heat exchanger. A portion of the low-temperature drying air directly enters the heat exchanger, while the other portion is diverted. This diversion stabilizes the system air pressure, reduces air loss and leakage, and prevents contaminated air that has circulated within the system from flowing into the uncontaminated area. Furthermore, the diverted air can be recycled into the high-temperature mixing chamber, reducing the generation of new pollutants.

[0042] In this embodiment, the high-temperature mixing chamber enables uniform air mixing and stable temperature of the mixed hot air with minimal fluctuations, thereby ensuring stable heating of the entire system. The high-temperature hot air output from the hot air furnace is mixed evenly with the system leakage air and then used as the high-temperature hot air supplied to the heat exchanger.

[0043] In a further embodiment of the invention, a closed-loop system is formed between the high-temperature mixing chamber, heat exchanger, dryer, collector, and condenser via multiple connecting pipes, and air sequentially enters between each device to form circulating air. This circulating air can be reused, thus saving energy. Simultaneously, the circulating air is not discharged, reducing environmental pollution and avoiding waste of thermal energy. The power for the system's air circulation can be derived from the drive of the hot air furnace.

[0044] In a further embodiment of the invention, the hot air outlet of the high-temperature mixing chamber is connected to the hot air inlet of the heat exchanger via a duct, the high-temperature drying air outlet of the heat exchanger is connected to the hot air inlet of the dryer via a duct, and the system air leakage outlet of the condenser is connected to the system air leakage inlet of the high-temperature mixing chamber via a duct. To maintain hot air circulation within the system, supplementary air is introduced into the hot air furnace. To treat the discharged waste gas, the waste gas outlet of the heat exchanger is connected to a waste gas treatment device via a connecting pipe. The polluted waste gas discharged from the heat exchanger is purified before being released, thus avoiding environmental pollution.

[0045] In a further embodiment of the present invention, the waste gas treatment device may also be installed between the hot air outlet of the high-temperature mixing chamber and the hot air inlet of the heat exchanger to perform preliminary treatment on the high-temperature hot gas.

[0046] In a further embodiment of the present invention, the collector is specifically selected as a cyclone separator, which can utilize the rotational motion of the airflow and the difference in settling velocity of different material particle sizes to achieve the separation of the dried product and the low-temperature humid air.

[0047] In a further embodiment of the present invention, the heat exchanger is a finned tube heat exchanger or a plate heat exchanger.

[0048] Based on the above system, the drying process of the present invention is as follows:

[0049] The wet municipal sludge to be treated enters the dryer through the material inlet for drying. During the drying process, the sludge absorbs heat and undergoes a phase change, turning into steam that enters the drying air. The hot air is cooled by heat absorption, forming low-temperature humid air. The mixed dried product and the low-temperature humid air enter the collector for separate collection. The dried product is discharged from the material outlet of the collector, while the low-temperature humid air enters the condenser for dehumidification, transforming into low-temperature dry air. A portion of the low-temperature dry air enters the heat exchanger, while a small portion is used as diversion air, i.e., system leakage air, and enters the high-temperature mixing chamber for reuse. The hot air furnace heats the high-temperature mixing chamber, and the resulting hot air heats the low-temperature dry air in the heat exchanger, thus obtaining high-temperature dry air. The high-temperature dry air is then used as circulating hot air in the dryer and re-enters the system for circulation. The waste gas treatment device is located after the heat exchanger, treating the generated waste gas to meet standards before discharge to avoid environmental pollution.

[0050] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make any modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. An environmentally friendly municipal sludge drying system, characterized in that, include: The dryer uses a gas drying method. Its material inlet receives the wet sludge to be processed, and the gas source inlet is connected to high-temperature drying air. The high-temperature drying air is used to dry the wet sludge. The collector has its material inlet connected to the dry material outlet of the dryer, collects the dried product, and discharges low-temperature, humid air. A condenser condenses the low-temperature, humid air to obtain condensate and low-temperature, dry air; A heat exchanger is used to exchange heat between high-temperature hot air and low-temperature dry air to obtain exhaust gas and high-temperature dry air. A hot air furnace is used to introduce and heat cold air to provide the high-temperature hot air to the heat exchanger. A high-temperature mixing chamber, located after the hot air furnace, thoroughly mixes the system leakage air and the hot air from the hot air furnace to obtain mixed hot air, which provides high-temperature hot air to the heat exchanger. The system leakage air is a diversion of low-temperature drying air; part of the low-temperature drying air enters the heat exchanger, and the other part enters the high-temperature mixing chamber as diversion air. The high-temperature mixing chamber, heat exchanger, dryer, collector, and condenser are connected by multiple sections of pipes to form a circulation system, and air flows through each piece of equipment in sequence to form circulating air. The heat exchanger includes a high-temperature hot air inlet, a low-temperature dry air inlet, a high-temperature dry air outlet, and an exhaust gas outlet. The high-temperature hot air heats the low-temperature dry air to obtain high-temperature dry air, and the high-temperature hot air and the low-temperature dry air do not come into direct contact, but only transfer heat energy.

2. The environmentally friendly municipal sludge drying system according to claim 1, characterized in that, The hot air outlet of the high-temperature mixing chamber is connected to the hot air inlet of the heat exchanger through a duct. The high-temperature drying air outlet of the heat exchanger is connected to the hot air inlet of the dryer through a duct. The system air leakage outlet of the condenser is connected to the system air leakage inlet of the high-temperature mixing chamber through a duct. Supplementary air is introduced at the hot air furnace.

3. The environmentally friendly municipal sludge drying system according to claim 2, characterized in that, The waste gas treatment device is connected to the waste gas outlet of the heat exchanger via a connecting pipe, and the waste gas treatment device purifies the polluted waste gas discharged from the waste gas outlet of the heat exchanger.

4. The environmentally friendly municipal sludge drying system according to claim 1, characterized in that, The collector is a cyclone separator, which uses the rotational motion of the airflow and the difference in settling velocity of different material particle sizes to separate the dried product from the low-temperature humid air.

5. An environmentally friendly municipal sludge drying method, implemented based on the environmentally friendly municipal sludge drying system according to any one of claims 1 to 4, characterized in that, The process is as follows: The wet sludge to be treated is sent into a dryer and dried using high-temperature drying air. During the drying process, the sludge absorbs heat and changes phase to vapor, which enters the drying air. The hot air is cooled down by heat absorption, forming low-temperature humid air. The dried product and the low-temperature humid air are fed into a collector, where the dried product is collected and the low-temperature humid air is discharged. The low-temperature humid air is sent into a condenser for dehumidification to obtain low-temperature dry air, which is then divided into two parts. Cold air is heated by a hot air furnace to obtain high-temperature hot air; a portion of low-temperature dry air is used as a diversion air, i.e., system leakage air, and enters the high-temperature mixing chamber to mix with the high-temperature hot air to obtain the final high-temperature hot air, and the final high-temperature hot air is sent into the heat exchanger. Another portion of the low-temperature drying air and the final high-temperature hot air are exchanged through a heat exchanger to obtain high-temperature drying air, which is then returned to the dryer. The moisture content of the wet sludge is 70%~80%, the moisture content of the dried product is reduced to 8%~12%, the temperature range of the high-temperature drying air is 200℃~850℃, the temperature of the low-temperature humid air is 70℃~80℃ with a moisture content of 30%~40%, the temperature range of the low-temperature drying air is 50℃~70℃, and the temperature range of the high-temperature hot air is 350℃~850℃.

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