WO2022142098A1

WO2022142098A1 - Low-calorific-value sludge smoldering treatment method

Info

Publication number: WO2022142098A1
Application number: PCT/CN2021/095940
Authority: WO
Inventors: 乔瑜; 冯超; 黄经春; 高翔鹏; 徐明厚
Original assignee: 华中科技大学
Priority date: 2020-12-30
Filing date: 2021-05-26
Publication date: 2022-07-07
Also published as: CN112797422A; CN112797422B

Abstract

A low-calorific-value sludge smoldering treatment method, comprising: mixing low-calorific-value sludge with an auxiliary fuel and a porous medium and then placing into a smoldering furnace for smoldering, where the proportions of the low-calorific-value sludge, the auxiliary fuel, and the porous medium respectively are 16.6% to 21.4%, 2.8% to 5.0%, and 75% to 80%. This expands schemes for treating low-calorific-value sludge and provides excellent economy.

Description

A kind of low calorific value sludge smoldering treatment method

【Technical field】

The invention belongs to the technical field related to solid waste treatment, and more particularly, relates to a low-calorific value sludge smoldering treatment method.

【Background technique】

Smoldering treatment is a new direct combustion treatment technology for organic solid waste with high water content and low calorific value. The organic solid waste that cannot be directly and independently burned in a conventional combustion device can be mixed with porous media fillers, and the smoldering technology can be used to provide a small amount of external heat. . However, since the calorific value of sludge and the like when the ash content reaches 40% or more of the dry basis mass, the smoldering treatment cannot be achieved by the conventional smoldering treatment conditions.

In the traditional flame combustion field, low calorific value fuels are often blended, but during blending, the main body of combustion after blending is still high calorific value combustion, and the low calorific value combustion quality accounts for 5% to 30%. It cannot meet the batch processing of low calorific value fuels with high ash content. Therefore, it is urgent to design a new low calorific value sludge smoldering treatment method to meet the increasing treatment demand for low calorific value fuels.

[Content of the invention]

In view of the above defects or improvement needs of the prior art, the present invention provides a low calorific value sludge smoldering treatment method, which firstly mixes the low calorific value sludge with a small amount of auxiliary fuel and a large amount of porous media to realize the improvement of the low calorific value sludge. Therefore, the sludge with low calorific value can also be treated by the smoldering process, and the treatment method of sludge with low calorific value is expanded. The treatment method is simple and economical.

In order to achieve the above object, according to one aspect of the present invention, a method for treating low calorific value sludge smoldering is provided. Combustion, wherein the proportions of the low calorific value sludge, auxiliary fuel and porous medium are 16.6%-21.4%, 2.8%-5.0% and 75%-80% respectively.

Preferably, the auxiliary fuel is agricultural and forestry waste.

Preferably, the auxiliary fuel is one or several mixtures of sawdust, rice husk or straw.

Preferably, the calorific value of the auxiliary fuel is greater than or equal to 15 MJ/kg, and the particle size of the auxiliary fuel is less than or equal to 0.5 mm.

Preferably, the porous medium is sand or slag.

Preferably, the particle size of the porous medium ranges from 0.5 mm to 2 mm.

Preferably, the mixing of the low calorific value sludge with the auxiliary fuel and the porous medium and then putting it into the smoldering furnace for smoldering combustion is specifically as follows: putting the mixture into the smoldering furnace, and continuing the bottom mixture at a temperature of 220°C to 300°C. Heating, while supplying air at a Darcy flow rate of 2.0cm/s to 6.5cm/s from the bottom of the furnace upwards, until the mixture reaches 400°C to 600°C.

Preferably, the low calorific value sludge is sludge with a moisture content greater than 80%, or a moisture content between 70% and 80% and a dry ash content between 23% and 48%, or a moisture content between 60% and 70%. % and the dry ash base is between 48% and 61%, or the calorific value is less than 1.6MJ/kg of sludge.

Preferably, the moisture content of the low calorific value sludge is 80%, and the proportions of the low calorific value sludge, auxiliary fuel and porous medium are 20.8%, 4.2% and 75%, respectively.

In general, compared with the prior art through the above technical solutions conceived by the present invention, a low-calorific value sludge smoldering treatment method provided by the present invention has the following beneficial effects:

1. Mixing the low calorific value sludge that cannot achieve smoldering with a small amount of auxiliary fuel and appropriate porous media can realize the smoldering treatment of low calorific value sludge, which significantly expands the treatment route of low calorific value sludge;

2. The auxiliary fuels added to the low calorific value sludge are agricultural and forestry wastes such as sawdust and rice husks, and the amount is only 2.8% to 5.0%. First, the price of agricultural and forestry wastes is very cheap. The quantity is very small and the economy is good;

3. The porous medium layer is cheap and easy-to-obtain sand and slag, which is simple and easy to obtain, easy to manufacture, and convenient for industrial application;

4. For the common low calorific value sludge with a moisture content of about 80%, when the ratio of low calorific value sludge, auxiliary fuel and porous medium is 20.8%, 4.2% and 75% respectively, both smoldering and smoldering can be achieved. To achieve the maximum treatment capacity of low calorific value sludge, with the best economy;

5. The present application can process low calorific value sludge with high water content, and solves the technical problem that the existing technology cannot process the sludge with high water content.

【Description of drawings】

FIG. 1 schematically shows a flow chart of the low calorific value sludge smoldering treatment method of the present embodiment.

【Detailed ways】

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

The present invention provides a low calorific value sludge smoldering treatment method, as shown in FIG. 1 , the method includes mixing the low calorific value sludge with auxiliary fuel and porous medium and putting it into a smoldering furnace for smoldering combustion, wherein, The proportions of the low calorific value sludge, auxiliary fuel and porous medium are respectively 16.6%-21.4%, 2.8%-5.0% and 75%-80%. Further, for common low calorific value sludge with a moisture content of about 80%, the proportions of low calorific value sludge, auxiliary fuel and porous medium are preferably 20.8%, 4.2% and 75%, respectively.

The low calorific value sludge is sludge with a moisture content greater than 80%, or a moisture content between 70% and 80% and a dry ash content between 23% and 48%, or a moisture content between 60% and 70% and a dry Ash base is between 48% and 61%, or sludge with calorific value less than 1.6MJ/kg.

The calorific value of the auxiliary fuel is greater than or equal to 15MJ/kg, and the particle size of the auxiliary fuel is less than or equal to 0.5mm. Further, the auxiliary fuel is agricultural and forestry waste, more preferably one or several mixtures of sawdust, rice husk or straw.

The porous medium is sand or slag. The particle size of the porous medium is 0.5mm˜2mm.

The mixing of the low calorific value sludge with the auxiliary fuel and the porous medium and then putting it into the smoldering furnace for smoldering combustion is specifically: putting the mixture into the smoldering furnace, and continuously heating the bottom mixture at 220° C. to 300° C. Air is supplied from the furnace bottom upward at a Darcy flow rate of 2.0cm/s to 6.5cm/s until the mixture reaches 400°C to 600°C.

The smoldering working condition is preferably a self-sustaining working condition, that is, a working condition that satisfies the self-sustaining characteristics of the smoldering treatment process, usually: the heating target temperature is 220℃～300℃, more preferably 250℃; the heating time is 2～4h, further It is preferably 3h, and the Darcy flow rate of the air supply in the smoldering furnace is 2.0cm/s～6.5cm/s, more preferably 3.5cm/s.

During smoldering treatment, firstly, the low calorific value sludge to be treated is mixed with auxiliary fuel and porous medium, and then the mixture is put into the smoldering treatment device and heated by one ignition (the target heating temperature of the bottom filler is 220℃～300℃) , and through continuous air supply, the flow rate of the air supply is 2.0cm/s～6.5cm/s, and the smoldering reaction is self-sustained in the direction of air flow (the average propagation speed of the reaction surface is 0.18cm/min～0.62cm/min) , until all sludge undergoes smoldering reaction at 400℃～600℃. The porous media in the smoldering ash can also be recycled.

Example 1

A municipal sludge with a moisture content of 80% and a dry ash content of 45% was evenly mixed with sawdust and sand in the proportions of 20.8%, 4.2% and 75%, and then added to a smoldering furnace with a diameter of 1.13m, and heated to the bottom for 3 hours. When the temperature of the filler reaches 250°C, forced air is supplied to the furnace from bottom to top, and the Darcy flow rate in the furnace is 3.3cm/s. At this time, the disposal amount of municipal sludge of about 49.7kg/h can be realized.

Example 2

A municipal sludge with a moisture content of 80% and a dry ash content of 45% was evenly mixed with sawdust and sand at a ratio of 16.6%, 3.4% and 80%, and then added to a smoldering furnace with a diameter of 1.13m, and the temperature was raised to the bottom for 3 hours. When the temperature of the filler reaches 250°C, the forced air supply starts from the bottom to the top in the furnace, and the Darcy flow rate in the furnace is 3.3cm/s. At this time, the disposal amount of municipal sludge of about 34.3kg/h can be realized.

Example 3

A municipal sludge with a moisture content of 80% and a dry ash content of 45% was evenly mixed with sawdust and sand in the proportions of 18%, 2.8% and 79.2%, and then added to a smoldering furnace with a diameter of 1.13m, and heated to the bottom for 3 hours. When the temperature of the filler reaches 250℃, the forced air supply starts from bottom to top in the furnace, and the Darcy flow rate in the furnace is 3.3cm/s. At this time, the disposal amount of municipal sludge of about 28.2kg/h can be realized.

Example 4

A municipal sludge with a moisture content of 80% and a dry ash content of 45% was evenly mixed with sawdust and sand in the proportions of 21.4%, 3.5% and 75.1%, and then added to a smoldering furnace with a diameter of 1.13m, and the temperature was raised to the bottom for 3 hours. When the temperature of the filler reaches 250°C, the forced air supply starts from the bottom to the top in the furnace. The Darcy flow rate in the furnace is 3.3cm/s. At this time, the disposal amount of municipal sludge can be realized at about 30.4kg/h.

Example 5

A municipal sludge with a moisture content of 80% and a dry ash content of 45% was evenly mixed with sawdust and sand at a ratio of 18%, 5.0% and 77%, and then added to a smoldering furnace with a diameter of 1.13m, and the temperature was raised to the bottom for 3 hours. When the temperature of the filler reaches 250°C, the forced air supply starts from the bottom to the top in the furnace. The Darcy flow rate in the furnace is 3.3cm/s. At this time, the disposal amount of municipal sludge of about 32.5kg/h can be realized.

Example 6

A municipal sludge with a moisture content of 80% and a dry ash content of 45% was evenly mixed with rice husks and slag at a ratio of 20.8%, 4.2%, and 75%, and then added to a smoldering furnace with a diameter of 1.13 m. The temperature was increased for 3 hours to When the temperature of the bottom filler reaches 250°C, forced air supply starts from bottom to top in the furnace, and the Darcy flow rate in the furnace is 3.3cm/s. At this time, the disposal amount of municipal sludge of about 45.2kg/h can be realized.

To sum up, in the low-calorific value sludge smoldering treatment method of the present application, the low-calorific value sludge is first mixed with a small amount of auxiliary fuel and a large amount of porous media to realize the modification of the low-calorific value sludge, thereby making the low-calorific value sludge. It can also be treated by smoldering process, expanding the treatment method of low calorific value sludge.

Those skilled in the art can easily understand that the above are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention, etc., All should be included within the protection scope of the present invention.

Claims

A low calorific value sludge smoldering treatment method, characterized in that the method comprises:

The low calorific value sludge, auxiliary fuel and porous medium are mixed and put into a smoldering furnace for smoldering combustion, wherein the proportions of the low calorific value sludge, auxiliary fuel and porous medium are 16.6% to 21.4% and 2.8% respectively. ~ 5.0% and 75% ~ 80%.
The method according to claim 1, wherein the auxiliary fuel is agricultural and forestry waste.
The method according to claim 2, wherein the auxiliary fuel is one or more mixtures of sawdust, rice husk or straw.
The method according to claim 2 or 3, wherein the calorific value of the auxiliary fuel is greater than or equal to 15MJ/kg, and the particle size of the auxiliary fuel is less than or equal to 0.5mm.
The method of claim 1, wherein the porous medium is sand or slag.
The method according to claim 5, wherein the particle size of the porous medium is 0.5 mm to 2 mm.
The method according to claim 1, wherein the mixing the low calorific value sludge with auxiliary fuel and porous medium into the smoldering furnace for smoldering combustion is specifically: putting the mixture into the smoldering furnace, The bottom mixture is continuously heated at 220°C to 300°C, while air is supplied from the furnace bottom upward at a Darcy flow rate of 2.0cm/s to 6.5cm/s, until the mixture reaches 400°C to 600°C.
The method according to claim 1, wherein the low calorific value sludge is sludge with a moisture content greater than 80%, or a moisture content between 70% and 80% and a dry basis ash content between 23% and 48%. , or a sludge with a moisture content of 60% to 70% and a dry ash base of 48% to 61%, or a calorific value of less than 1.6 MJ/kg.
The method according to claim 1 or 8, wherein the low calorific value sludge has a water content of 80%, and the proportions of the low calorific value sludge, auxiliary fuel and porous medium are 20.8% and 4.2%, respectively. and 75%.