CN108439743A - Biogas residue deep dehydration and the method for desiccation after a kind of anaerobic digestion - Google Patents

Abstract

The invention belongs to field of environment protection, biogas residue deep dehydration and the method for desiccation after a kind of anaerobic digestion are provided, is included the following steps：a）Pretreatment：The solid content for entering the biogas residue of pyrohydrolysis system is adjusted using excess sludge, solid content is adjusted to 8% or more, and into high-temperature-hot-water solution device, hydrolysis temperature is 150 ~ 170 DEG C, hydrolysis time is 30 40min, and the biogas residue after hydrolysis enters deep dehydration after heat exchange is cooling；b）Deep dehydration：Flocculant PAM is added, moisture content is dropped to 60% or less by 92% using electrolysis drying process；c）Solar energy desiccation：Biogas residue after deep dehydration is entered into solar energy desiccation factory moisture content after solar energy desiccation by screw conveyor and is down to 40% hereinafter, the above percentage is mass percent.The present invention improves the efficiency of biogas residue dehydration, and pretreatment can kill all pathogenic bacteria, be conducive to its recycling, and operating cost is low.

Description

A method for deep dehydration and drying of biogas residue after anaerobic digestion

technical field

The invention belongs to the field of environmental protection and relates to a method for deep dehydration and drying of biogas residue after anaerobic digestion.

Background technique

As the total amount of sewage treatment increases year by year, the amount of sludge treatment also increases year by year, and the treatment and disposal of sludge has become an important problem to be solved urgently. Sludge anaerobic digestion technology has become one of the effective ways to make sludge harmless, reduce, and recycle sludge. After anaerobic digestion, biogas residues are used for landscaping and other purposes. Deep dehydration of biogas residues becomes a resource utilization of biogas residues. The basics.

At present, there are mainly three methods for deep dehydration of biogas residues: solar drying takes up a large area, depends on climatic conditions, takes a long time to dry, and has low drying efficiency; after chemical conditioning, plate and frame filter presses need to add lime, iron, etc. Inorganic flocculants such as salt change the characteristics of sludge, and this method will have a certain impact on subsequent resource utilization; high-voltage pulse electrolytic dehydration consumes a lot of energy and dewaters high costs; the degree of automation of plate and frame dehydration is not high, and the scale of dehydration is limited.

Contents of the invention

1. Technical problems to be solved:

In the existing method of deep dehydration of biogas residues, Taineng drying takes up a large area and depends on climatic conditions. High-voltage pulse electrolytic dehydration consumes a lot of energy and dehydration costs are high.

2. Technical solution:

Aiming at the deficiencies of the existing biogas residue dehydration methods, the present invention provides a method for deep dehydration and drying of biogas residue after anaerobic digestion, including the following steps: a) Pretreatment: use the remaining sludge to dehydrate the biogas residue entering the thermal hydrolysis system The solid content of the slag is adjusted, the solid content is adjusted to more than 8%, and it enters the high-temperature thermal hydrolysis device. The hydrolysis temperature is 150-170°C, and the hydrolysis time is 30-40min. Deep dehydration; b) Deep dehydration: add flocculant PAM, and use electrolytic drying process to reduce the water content from 92% to below 60%; c) Solar drying: The biogas residue after deep dehydration enters the solar drying process through a screw conveyor. The moisture content of the chemical plant is reduced to below 40% after solar drying, and the above percentages are mass percentages.

Further, the PAM added in the deep dehydration is 6/10000-7/10000 of the dry weight of the sludge.

3. Beneficial effects:

The method for deep dehydration and drying of biogas residues after anaerobic digestion provided by the present invention uses high-temperature thermal hydrolysis pretreatment to destroy the floc and cell structure of biogas residues, and the water and cells in biogas residues absorbed by extracellular polymers The internal bound water is released, and more bound water is converted into free water, which reduces the difficulty of subsequent biogas residue dehydration; the whole process of electrolytic drying process is fully automatic control, continuous operation, high work efficiency, low operating cost; electrolysis process will A temperature of about 80°C is generated, and the biogas residue will have a certain temperature after entering the solar drying plant. The moisture in the biogas residue is very volatile, and there is no need for an external auxiliary heat source for heat tracing, which significantly improves the efficiency of solar drying.

Detailed ways

The present invention will be described in detail below by way of examples.

The invention provides a method for deep dehydration and drying of biogas residues after anaerobic digestion, including the following steps: a) Pretreatment: using excess sludge to adjust the solid content rate of biogas residues entering the thermal hydrolysis system, and the solid content Adjust the rate to above 8%, enter the high-temperature thermal hydrolysis device, the hydrolysis temperature is 150-170 ℃, and the hydrolysis time is 30-40min. Pretreatment, through high-temperature thermal hydrolysis pretreatment, destroys the floc and cell structure of the biogas residue, releases the water absorbed by the extracellular polymer and the bound water in the cell, and converts more bound water into free water. The difficulty of subsequent biogas residue dehydration is reduced.

b) Deep dehydration: add flocculant PAM, and use electrolytic drying to reduce the moisture content from 92% to below 60%; c) Solar drying: the biogas residue after deep dehydration enters the solar drying plant through a screw conveyor and passes through the solar energy. After drying, the moisture content drops below 40%, and the above percentages are mass percentages. In the electrolytic drying of deep dehydration, a temperature of about 80°C will be generated. After entering the solar drying plant, the biogas residue will have a certain temperature. The efficiency of solar drying.

Example 1

A method for deep dehydration and drying of biogas residues after anaerobic digestion, comprising the following steps: a) Pretreatment: using excess sludge to adjust the solid content of biogas residues entering the thermal hydrolysis system, the solid content is adjusted to More than 8%, enter the high-temperature thermal hydrolysis device, the hydrolysis temperature is 150°C, and the hydrolysis time is 30 minutes. The hydrolyzed biogas residue enters deep dehydration after heat exchange and cooling; b) Deep dehydration: add flocculant PAM, and use electrolytic drying The process reduces the moisture content to 58%; c) Solar drying: the deeply dehydrated biogas residue enters the solar drying plant through a screw conveyor and the moisture content drops to 38% after solar drying, the above percentages are mass percentages.

The PAM added in the deep dehydration is 7/10000 of the dry weight of the sludge.

Example 2

A method for deep dehydration and drying of biogas residues after anaerobic digestion, comprising the following steps: a) Pretreatment: using excess sludge to adjust the solid content of biogas residues entering the thermal hydrolysis system, the solid content is adjusted to More than 8%, enter the high-temperature thermal hydrolysis device, the hydrolysis temperature is 170°C, and the hydrolysis time is 40min. The hydrolyzed biogas residue enters deep dehydration after heat exchange and cooling; b) deep dehydration: add flocculant PAM, and use electrolytic drying The process reduces the moisture content to 56%; c) Solar drying: the deeply dehydrated biogas residue enters the solar drying plant through a screw conveyor and the moisture content drops to 36% after solar drying, the above percentages are mass percentages.

The PAM added in the deep dehydration is 6/10000 of the dry weight of the sludge.

Although the present invention has been disclosed as above with preferred embodiments, they are not intended to limit the present invention. Any skilled person can make various changes or modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be defined by the protection scope of the claims of the present application.

Claims (2)

1. biogas residue deep dehydration and the method for desiccation, include the following steps after anaerobic digestion：a）Pretreatment：Utilize excess sludge The solid content of biogas residue to entering pyrohydrolysis system is adjusted, and solid content is adjusted to 8% or more, into high-temperature-hot-water solution device, water It is 150 ~ 170 DEG C, hydrolysis time 30-40min to solve temperature, and the biogas residue after hydrolysis enters deep dehydration after heat exchange is cooling； b）Deep dehydration：Flocculant PAM is added, moisture content is dropped to 60% or less by 92% using electrolysis drying process；c）The sun is competent Change：Biogas residue after deep dehydration is entered solar energy desiccation factory moisture content after solar energy desiccation by screw conveyor to be down to 40% hereinafter, the above percentage is mass percent.

2. the method as described in claim 1, the PAM being added in deep dehydration is the 6/10000-7/10000 of mud dry weight.