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Multi-stage drying method of sludge utilizing compressed secondary steam

A technology of secondary steam and drying method, applied in the direction of dehydration/drying/concentrated sludge treatment, etc., can solve the problems of large power loss of secondary steam compression device, low cleanliness of secondary steam, poor fluidity of sludge, etc. Significant energy-saving effect, low viscosity, and clean heat exchange surface

Inactive Publication Date: 2011-11-30
HANGZHOU DIANZI UNIV +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] It can be seen that for sludge drying, due to the poor fluidity and easy bonding of sludge, if the above-mentioned drying method is directly used for sludge drying, the scaling and secondary steam cleanliness of the sludge during the drying process will be significantly reduced. Low, high dust content, low drying efficiency and other problems are difficult to solve
Moreover, due to the poor fluidity of the sludge and the low drying rate, when a single-stage dryer is used, the power loss of the secondary vapor compression device is also large

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0040] The dewatered sludge produced in the sewage treatment process and the heavy oil obtained from petroleum refining are evenly mixed into oil sludge according to the weight ratio of 5:1.

[0041] A horizontal disc dryer and an indirect heating fluidized bed dryer are connected in series to form a two-stage dryer. Start the two-stage dryer, send the oil sludge into the drying chamber of the first-stage horizontal disc dryer, and at the same time introduce external steam into its heating chamber, and discharge it out of the dryer after heat exchange, which can be recycled after heating. In the drying chamber of the first-stage horizontal disc dryer, the oil sludge is dried and evaporates to produce secondary steam. The oil sludge after the primary drying is sent to the drying chamber of the second-stage indirect heating fluidized bed dryer for drying, and the secondary steam is evaporated. After the secondary steam evaporated in the drying chamber of the two-stage dryer is le...

Embodiment 2

[0045] The dewatered sludge produced in the sewage treatment process and the light oil obtained from petroleum refining are evenly mixed into oil sludge according to the weight ratio of 20:1.

[0046] Three sets of paddle dryers are connected in series to form a three-stage dryer. Start the dryers at all levels, send the sludge to the drying chamber of the first-stage paddle dryer for drying, and the sludge after the first-stage drying is sent to the drying chambers of the second-stage and third-stage paddle-type dryers for drying . Introduce external steam into the heating chamber of the second-stage dryer, and discharge it out of the dryer after heat exchange, which can be recycled after heating. The sludge generates secondary steam in the drying chamber of the second-stage paddle dryer. After the secondary steam is led out of the drying chamber, the saturated secondary steam is separated through the gravity separator, and the condensed water and tail gas are discharged. T...

Embodiment 3

[0051] The dewatered sludge produced in the sewage treatment process and waste rubber and plastic pyrolysis oil are evenly mixed into sludge according to the weight ratio of 10:1.

[0052] Five sets of vertical disc dryers are connected in series to form a five-stage dryer. Start the dryers at all levels, send the sludge into the drying chamber of the first-stage vertical disc dryer, and send the sludge after the first-stage drying to the drying chambers of the second to fifth-stage vertical disc dryers for drying. The heat transfer oil is introduced into the heating chamber of the fifth stage dryer, and discharged out of the dryer after heat exchange, which can be recycled after heating. The sludge generates secondary steam in the drying chamber of the fifth-stage dryer. After the secondary steam is led out of the drying chamber, the centrifugal separator separates the saturated secondary steam and discharges condensed water and tail gas. The saturated secondary steam is com...

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Abstract

The invention relates to a multi-stage drying method of sludge utilizing compressed secondary steam. In the existing drying methods, energy consumption is high and efficiency is low. The method provided by the invention comprises the following steps: firstly uniformly mixing dewatered sludge with oil in a weight ratio of (1-20):1 to obtain oily sludge, and then drying the oily sludge by utilizing secondary steam, separating oil and dry sludge from the dried oily sludge, and recycling the separated oil used as a raw material for the mixed oily sludge. The oily sludge is dried by a multi-stage dryer composed of 2-5 dryers connected in series; an external heat source is utilized by one of the dryers; and secondary steam is utilized by the remaining dryers, specifically saturated secondary steam is separated from the secondary steam generated in the drying process and compressed into superheated steam, and the superheated steam is introduced into heating chambers of the dryers to be used as a heat source. In the multi-stage drying method provided by the invention, the heat energy of the secondary steam is sufficiently utilized, and the energy consumption of the drying system is greatly reduced; and no dust entraining exists in the drying process, so that the heat transfer surface of the drying device is maintained clean, and the drying efficiency is high.

Description

technical field [0001] The invention relates to a sludge drying method, in particular to a multistage drying method for secondary vapor compression of sludge, and belongs to the technical field of waste treatment. Background technique [0002] A large amount of sludge is produced in the process of sewage treatment, and the improvement of sewage treatment rate and sewage treatment standard has led to an increase in the amount of sludge produced. Because the water content of the sludge after mechanical dehydration is extremely high (up to about 80%), and the sludge generally contains a large amount of harmful chemicals and heavy metals and other pollutants. Therefore, direct landfill or agricultural use of high-moisture sludge is generally prohibited at home and abroad. Sludge thermochemical treatment methods (such as sludge incineration, pyrolysis, etc.) have the advantages of harmlessness and thorough reduction. It is a very promising sludge resource treatment method, which...

Claims

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Application Information

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IPC IPC(8): C02F11/14
Inventor 张志霄马加德
Owner HANGZHOU DIANZI UNIV
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