Low-temperature sludge drying system based on multi-stage heat utilization

Abstract

The invention discloses a multi-stage heat utilization-based sludge low-temperature drying system. The multi-stage heat utilization-based sludge low-temperature drying system comprises a heat treatment device, a guiding device, a dewatering device, a drying device, a low-temperature drying device and a tail gas processing device; original sludge is heated in the heat treatment device and flows through the drying device via the guiding device and then into the dewatering device; the drying device comprises a hot sludge pipe and a sludge conveying device; the dewatering device comprises a stirring barrel, a plate-and-frame filter press and a pulverizer; optionally, the sludge can be conditioned inside the stirring barrel or directly flows into the plate-and-frame filter press for dewatering,the dewatered sludge is crushed and then conveyed back to the sludge conveying device to exchange heat with the heated sludge inside the hot sludge pipe; tail gas exhausted by the drying device enters the tail gas processing device, and purified tail gas is fed into the low-temperature drying device for drying the dewatered sewage inside the sewage conveying device. The multi-stage heat utilization-based sludge low-temperature drying system reduces energy consumption through multi-stage heat utilization, and reduces pollutant discharge through low-temperature drying, thereby being environmentally friendly.

Description

technical field [0001] The invention relates to the technical field of sludge drying treatment, in particular to a low-temperature sludge drying system based on multi-stage heat utilization. [0002] technical background [0003] With the development of the economy and the process of urbanization, the output of municipal sludge in my country has also increased significantly, and the harmless and reduction treatment of sludge has become a hot environmental issue today. However, the moisture content of sludge obtained by traditional mechanical dehydration is generally 75% to 85%, which cannot meet the standards for subsequent treatment. Therefore, if the moisture content of sludge is to be further reduced, thermal drying must be carried out. [0004] In the field of sludge drying treatment technology, Chinese patent application CN201410536566.6 discloses a sludge drying platform device, which uses hot water to exchange heat with air through a radiator, and then uses hot air to...

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Problems solved by technology

[0004] In the field of sludge drying treatment technology, Chinese patent application CN201410536566.6 discloses a sludge drying platform device, which uses hot water to exchange heat with air through a radiator, and then uses hot air to dry sludge. The manufacturing cost is low, Simple to use, but because there is no multi-level utilization of heat, the energy consumption is large and the operating cost of the system is relatively high

[0005] Chinese patent application CN200920062589.2 discloses a composite heating disc sludge dryer, which introduces waste heat steam and high-temperature flue gas at the same time on the basis of ordinary disc dryers to dry sludge, and the drying efficiency is high; However, a higher drying temperature will lead to an increase in pollutant emissions and cause secondary harm to the environment

Although the cost is saved, the drying efficiency is reduced and the drying time is increased due to multiple heat transfers.

[0007] Chinese patent application CN201710590244.3 discloses a sludge drying system based on energy cascade utilization. The system uses hot steam as a heat source, and uses hot water generated by the disc drying system to heat the sludge in the filter press system, improving the Energy utilization efficiency, but at the same time relying on power plants and boiler plants to provide heat sources, there are certain geographical restrictions

[0009] 1. Use waste heat steam, heat transfer oil, etc. as heat sources to dry at high temperature (180-200°C), which consumes a lot of energy and increases the cost of drying

[0010] 2. High-temperature drying will produce a large amount of sulfur-containing and nitrogen-containing pollutants, and will emit foul-smelling gases during work, causing secondary pollution to the environment.

[0011] 3. Due to the low temperature of the drying medium and insufficient contact with the material, the drying efficiency is low and the drying time is prolonged

[0012] 4. The drying medium mostly uses waste heat flue gas, saturated steam, etc. as heat sources, and relies on power plants and boiler plants, so there are certain geographical restrictions on technical use

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