CN111018302A

CN111018302A - Process flow and method for drying sludge by two-stage method

Info

Publication number: CN111018302A
Application number: CN201911303079.4A
Authority: CN
Inventors: 王贤; 杨源
Original assignee: Safbon Water Service Holding Inc Shanghai
Current assignee: Safbon Water Service Holding Inc Shanghai
Priority date: 2019-12-17
Filing date: 2019-12-17
Publication date: 2020-04-17

Abstract

The invention provides a process flow and a method for drying sludge by a two-stage method, which comprises the following steps: (1) a first stage: the heat source provides heat to exchange heat with wet sludge, so that the wet sludge with the water content of more than or equal to 80% is converted into semi-dry sludge with the water content of 50% -60%; (2) and a second stage: and (2) carrying out heat exchange on the hot waste gas evaporated from the wet sludge in the step (1) and the semi-dry sludge to convert the semi-dry sludge into dry sludge with the water content of less than 30%. The process can recycle the hot waste gas evaporated from the wet sludge in the first section, and can save more than 40% of energy compared with the sludge drying process in the first section; the hot waste gas does not need to be cooled by circulating cooling water, so that a large amount of water resources can be saved.

Description

Process flow and method for drying sludge by two-stage method

Technical Field

The invention belongs to the field of sewage treatment, and particularly relates to a process flow and a method for drying sludge by a two-stage method.

Background

In the sewage treatment process, the sludge treatment is always a concern for the industry. The sludge of the sewage treatment plant mainly comprises sediment of a grit chamber and an oil separation tank, scum of an air flotation machine, residual activated sludge and chemical sludge of other process units. Sludge is a solid waste, and is a hazardous waste if one of the characteristics of acute toxicity, flammability, reactivity, corrosiveness, leaching toxicity, and disease infectivity.

The one-section sludge drying process utilizes heat provided by a drying machine heat source to evaporate moisture in wet sludge, dries the wet sludge with the moisture content of 80% into dry sludge with the moisture content of 30%, the temperature of waste steam generated by evaporation of the wet sludge can reach over 100 ℃, hot waste gas generated by evaporation of the wet sludge needs to be cooled by circulating cooling water, so that a large amount of heat energy is lost, and the purposes of saving energy and protecting the environment cannot be achieved.

If waste heat evaporated from wet sludge is to be recovered, the hot waste gas needs to be cooled by cooling water, and a large amount of circulating cooling water is needed in the process, so that water resource waste is caused. Therefore, there is a need to improve the existing one-stage sludge drying process to recycle the heat in the waste steam, so as to achieve the purposes of protecting the environment and saving energy.

Disclosure of Invention

The invention aims to solve the problems that one-stage sludge drying method is high in energy consumption, cannot be recycled and wastes serious water resources, and provides a process flow and a method for drying sludge by using a two-stage method.

In order to achieve the purpose, the invention adopts the following technical scheme to realize the purpose:

a process flow for drying sludge by a two-stage method is characterized by mainly comprising the following steps: the system comprises a heat source, a first section of sludge drying machine, a second section of sludge drying machine and a hot waste gas blower; the heat source is connected with an energy interface of the first section of sludge drying machine and supplies heat energy for wet sludge; the feed inlet of the first section of sludge drying machine is connected with the discharge outlet of the sludge tank, and the discharge outlet of the first section of sludge drying machine is connected with the feed inlet of the second section of sludge drying machine; the hot waste gas outlet of the first section of sludge drying machine is connected with the hot waste gas blower, and the hot waste gas blower is connected with the energy interface of the second section of sludge drying machine to supply heat energy for the semi-dry sludge; and a discharge port of the second section of sludge drying machine directly discharges dry sludge.

The invention discloses a method for drying sludge by a two-stage method, which is characterized by comprising the following steps of: (1) a first stage: the heat source provides heat to exchange heat with wet sludge, so that the wet sludge with the water content of more than or equal to 80% is converted into semi-dry sludge with the water content of 50% -60%; (2) and a second stage: and (2) carrying out heat exchange on the hot waste gas evaporated from the wet sludge in the step (1) and the semi-dry sludge to convert the semi-dry sludge into dry sludge with the water content of less than 30%.

The process can recover the hot waste gas evaporated by the first section of wet sludge and then carry out heat exchange with the second section of semi-dry sludge, so that the wet sludge with the water content of more than or equal to 80 percent is converted into the dry sludge with the water content of less than 30 percent, the effective recycling of energy is realized, and the energy can be saved by more than 40 percent compared with a one-section sludge drying process; meanwhile, as the hot waste gas does not need to be cooled by circulating cooling water, a large amount of water resources can be saved.

Drawings

FIG. 1 is a schematic diagram of a two-stage sludge drying process of the present invention;

in the figure: 1-heat source, 2-first section sludge drier, 3, second section sludge drier, 4, hot waste gas blower, 5-sludge tank, 6-hot waste gas circulation pipeline, 7-exhaust valve.

Detailed Description

The technical solutions of the present invention will be clearly and completely described below, and all other embodiments obtained by those skilled in the art without any creative efforts based on the embodiments of the present invention belong to the protection scope of the present invention.

As shown in fig. 1. A process flow for drying sludge by a two-stage method is characterized by mainly comprising the following steps: a heat source 1, a first section of sludge drier 2, a second section of sludge drier 3 and a hot waste gas blower 4; the heat source 1 is connected with an energy interface of the first section of sludge drying machine 2 and supplies heat energy for wet sludge; the feed inlet of the first section of sludge drying machine 2 is connected with the discharge outlet of the sludge tank, and the discharge outlet of the first section of sludge drying machine 2 is connected with the feed inlet of the second section of sludge drying machine 3; the hot waste gas outlet of the first section of sludge drying machine 2 is connected with the hot waste gas blower 4, and the hot waste gas blower 4 is connected with the energy interface of the second section of sludge drying machine 3 to supply heat energy for the semi-dry sludge; and a discharge port of the second section of sludge drying machine 3 directly discharges dry sludge.

Furthermore, a hot waste gas circulation pipeline 6 is further arranged on the second section of sludge drying machine 3 and connected with the hot waste gas blower 4, and an exhaust valve 7 is arranged on the hot waste gas circulation pipeline 6 and used for recycling hot waste gas and adjusting the air volume of the hot waste gas.

Further, the heat source is one or more of an electric energy heat source, a hot water heat source, a steam heat source, a solar heat source and a furnace kiln smoke heat source.

Further, the first section of sludge dryer 2 is a thin layer dryer; the second section of sludge drying machine 3 is a belt dryer.

Example 1

(1) Wet sludge with the water content of 83 percent from a sludge pool 5 is sent into a first-stage sludge drier 2 (a thin-layer drier), the feeding mass flow is 6000 kg/h, heat exchange is carried out between the wet sludge and a heat source 1 (steam, T =180 ℃, P =10 bar), the wet sludge is dried, the discharge port of the thin-layer drier is semi-dry sludge with the water content of 55 percent, and meanwhile, hot waste gas of the thin-layer drier is collected; (2) and (3) conveying the semi-dry sludge into a second section of sludge drying machine 3 (a belt dryer), blowing hot waste gas evaporated by the first section of wet sludge into the belt dryer through a hot waste gas blower 4 to remove part of water in the semi-dry sludge, wherein the discharge hole of the belt dryer is dry sludge with the water content of 28%, and the mass flow rate is 1666 kg/h. The process is used for drying wet sludge with the water content of 83 percent per ton, and the steam consumption of unit sludge is 0.54 kg/kg. The unit sludge steam consumption is 0.95 kg/kg by utilizing the traditional one-stage sludge drying process.

Example 2

Wet sludge with the water content of 80% from a sludge pool 5 is sent into a first-stage sludge drier 2 (a thin-layer drier), the feeding mass flow is 5000 kg/h, heat exchange is carried out between the wet sludge and a heat source 1 (steam, T =180 ℃, P =10 bar), the wet sludge is dried, the discharge port of the thin-layer drier is semi-dry sludge with the water content of 52%, and meanwhile, hot waste gas of the thin-layer drier is collected; (2) and (2) conveying the semi-dry sludge into a second section of sludge drying machine 3 (a belt dryer), blowing hot waste gas evaporated by the first section of wet sludge into the belt dryer through a hot waste gas blower 4 to remove part of water in the semi-dry sludge, wherein the discharge hole of the belt dryer is dry sludge with the water content of 27%, and the mass flow is 1370 kg/h. The process is used for drying wet sludge with the water content of 80 percent per ton, and the steam consumption of unit sludge is 0.52 kg/kg. The unit sludge steam consumption is 0.93 kg/kg by utilizing the traditional one-stage sludge drying process.

Claims

1. A process flow for drying sludge by a two-stage method is characterized by mainly comprising the following steps: a heat source (1), a first section of sludge drying machine (2), a second section of sludge drying machine (3) and a hot waste gas blower (4); the heat source (1) is connected with an energy interface of the first section of sludge drying machine (2); the feed inlet of the first section of sludge drying machine (2) is connected with the discharge outlet of the sludge tank, and the discharge outlet of the first section of sludge drying machine (2) is connected with the feed inlet of the second section of sludge drying machine (3); the hot waste gas outlet of the first section of sludge drying machine (2) is connected with the hot waste gas blower (4), and the hot waste gas blower (4) is connected with the energy interface of the second section of sludge drying machine (3); and a discharge port of the second section of sludge drying machine (3) directly discharges dry sludge.

2. The two-stage process according to claim 1, wherein a hot waste gas circulation line (6) is connected to the hot waste gas blower (4) on the second stage sludge drier (3), and a vent valve (7) is arranged on the hot waste gas circulation line (6).

3. The two-stage process according to claim 1, wherein the heat source of step (1) is one or more of an electric energy heat source, a hot water heat source, a steam heat source, a solar heat source, and a kiln flue gas heat source.

4. The two-stage process according to claim 1, wherein the first stage sludge drier (2) is a thin layer drier; the second section of sludge drying machine (3) is a belt dryer.

5. A two-stage process for drying sludge is characterized by comprising the following steps: (1) a first stage: the heat source provides heat to exchange heat with wet sludge, so that the wet sludge with the water content of more than or equal to 80% is converted into semi-dry sludge with the water content of 50% -60%; (2) and a second stage: and (2) carrying out heat exchange on the hot waste gas evaporated from the wet sludge in the step (1) and the semi-dry sludge to convert the semi-dry sludge into dry sludge with the water content of less than 30%.