CN108753324A - A kind of method of the production of hydrothermal carbonization maize straw humic acid and type briquette fuel - Google Patents

Abstract

A method for producing humic acid and block fuel by hydrothermally carbonizing corn stalks, which is characterized in that corn stalks and water are used as raw materials, stirred and mixed, and a hydrothermal carbonization reaction occurs in a hydrothermal reaction kettle, and the hydrothermal carbonization The product adopts the method of in-situ alkaline extraction to convert all the humic acid into water-soluble sodium humate. After the reaction is completed, the sodium humate solution and solid carbonized filter residue are obtained by suction filtration, and the suction filtrate is acidified and filtered to obtain humic acid. , or concentrate and dry the suction filtrate to obtain sodium humate, and mix solid carbonized filter residue with pulverized coal and form it to obtain block fuel. The main features of this operation process are that the process route is simple, the raw and auxiliary materials are cheap and easy to obtain, the energy consumption is low, the production cost is low, and the yield of humic acid is as high as 28.2%. The investment in equipment saves production water; the prepared corn stalk-type block fuel has the characteristics of high calorific value, high burnout rate, and no additional binder is needed; the production process is easy to industrialize, and the corn stalk biomass energy is effectively used.

Description

A method for producing humic acid and block fuel by hydrothermally carbonizing corn stalks

technical field

The invention relates to the field of biomass energy, in particular to a method for producing humic acid and block fuel by hydrothermally carbonizing corn stalks. It involves the treatment of corn stalks by hydrothermal method. The hydrothermal product is extracted with alkaline solution to obtain sodium humate, and the sodium humate is acidified to obtain humic acid solid precipitation. The solid carbonized filter residue after humic acid extraction is mixed with pulverized coal and formed to obtain corn. Straw type block fuel.

Background technique

Corn stalks are mainly composed of plant cell walls. The basic components are cellulose, hemicellulose and lignin. The structural composition determines that corn stalk is an important organic raw material and fuel.

At present, the main utilization methods of corn stalks include mechanized crushing and returning to the field, straw gasification, straw gasification, straw pellet feed processing, straw fermentation to ethanol, etc. Due to problems such as low technical maturity, large investment, and complicated process, there is a large amount of corn stalks stockpiled and burned in the field, which has caused serious air pollution and is also one of the reasons for the smog. In-situ burning of straw also reduces the organic matter content of the land. Therefore, how to turn waste corn straw into treasure and fundamentally solve the comprehensive utilization of corn straw is an urgent issue.

The Chinese patent with publication number CN104231116B introduces a method for obtaining hemicellulose stock solution, humate and feed additives by using straw as raw material through microbial fermentation treatment and alkaline hydrolysis. The method mainly includes the following steps: after the straw is pulverized, the wax on the straw surface is degraded by microbial fermentation treatment; The lye, steamed, and the solids obtained by pressing and filtering are feed additives; while the filtrate is rich in humate, concentrated and filtered to obtain humate solids. The process of this method is complicated and the production cost is relatively high; the biological fermentation treatment is adopted, and the requirements for the control of process parameters in the production process are high.

Contents of the invention

The purpose of the present invention is to provide a method for producing humic acid and block fuel by hydrothermally carbonizing corn stalks.

In order to achieve the above object, the technical solution adopted by the present invention includes: a method for producing humic acid and block fuel by hydrothermally carbonizing corn stalks, which is characterized in that: corn stalks and water are used as raw materials, stirred and mixed, and heated in hydrothermal A hydrothermal carbonization reaction occurs in the reaction kettle, and the hydrothermal carbonization product is converted into a water-soluble sodium humate by in-situ alkaline extraction. After the reaction is completed, the sodium humate solution and solid carbonized filter residue are obtained by suction filtration , acidify and filter the suction filtrate to obtain humic acid, or concentrate and dry the suction filtrate to obtain sodium humate, and mix and form solid carbonized filter residue with pulverized coal to obtain block fuel.

The beneficial effects of the present invention are:

1. The process route of the present invention is simple, the raw and auxiliary materials are cheap and easy to obtain, the energy consumption is low, and the yield of humic acid is high.

2. Using the hydrothermal method to hydrothermally carbonize corn stalks, the yield of humic acid is as high as 28.2%. After the hydrothermal carbonization reaction, the calorific value of the carbonized filter residue of corn stalks is increased; at the same time, the volume of corn stalks is significantly reduced and carbonized The volume of the filter residue only accounts for 30% of the corn stover powder.

3. The hydrothermal product of corn straw is subjected to in-situ alkaline extraction, and the hydrothermal reaction and alkaline extraction can be carried out in the same reactor, which not only saves equipment investment, but also saves production water.

4. The carbonized filter residue of corn stalks after hydrothermal alkali extraction is mixed with pulverized coal and formed to prepare briquettes, which increases the calorific value of briquettes, and the prepared briquettes have a high burnout rate, and the cold compressive strength and drop strength of the briquettes Both are higher.

5. After the corn stalk is hydrothermally carbonized, the toughness of the fiber is destroyed. As the raw material for the preparation of the fuel block, it can play the role of an organic binder, and can effectively reduce the expansion rate of the preparation of the coal, so in the preparation of the block fuel In the fuel process, it can be molded without adding a binder, effectively utilizing the energy of corn stalks.

Description of drawings

Fig. 1 is the flow chart of the present invention.

Detailed ways

The implementation of the present invention is described in further detail below:

A method for producing humic acid and block fuel by hydrothermally carbonizing corn stalks, characterized in that corn stalks and water are used as raw materials, stirred and mixed, and a hydrothermal carbonization reaction occurs in a hydrothermal reaction kettle, and the hydrothermal carbonization The product adopts the method of in-situ alkaline extraction to convert all the humic acid into water-soluble sodium humate. After the reaction is completed, the sodium humate solution and solid carbonized filter residue are obtained by suction filtration, and the suction filtrate is acidified and filtered to obtain humic acid. , or concentrate and dry the suction filtrate to obtain sodium humate, and mix solid carbonized filter residue with pulverized coal and form it to obtain block fuel. The process flow is shown in Figure 1.

In order to better understand the content of the present invention, the following will be further described in conjunction with specific embodiments, but it is not limited to any one of these embodiments or similar examples.

Example 1:

A method for producing humic acid and block fuel by hydrothermal carbonization of corn stalks described in this embodiment is carried out according to the following steps:

(1) Principle pretreatment: crush corn stalks to a particle size of less than 1 mm to obtain straw powder;

(2) Hydrothermal carbonization: 10.0 g (dry basis) of straw powder obtained in step (1) is packed into a polytetrafluoroethylene-lined hydrothermal reaction kettle, and 50, 100, 150, 200, 250ml of water, stir well and heat up to 200°C, react under hydrothermal conditions at 200°C for 3.0h, then cool to below 100°C.

(3) In-situ alkaline extraction: Add sodium hydroxide solid particles to the hydrothermal reaction liquid system in step (2) until the pH is about 13-14, stir, react for 30 minutes, and filter to obtain filtrate and solid carbonized filter residue.

(4) Preparation of corn stalk-type block fuel: Mix the solid carbonized filter residue obtained in step (3) with pulverized coal at a ratio of 1:4 to 1:10 (requires that the low calorific value of pulverized coal is greater than 21kJ/g, and the coal particle size is less than 3mm. In the process, pulverized coal with a low calorific value of 22.6kJ/g is used, the moisture content of the air-dried basis is 3.7%, and the particle size of the pulverized coal is 2mm), after adding an appropriate amount of water until the moisture content of the mixed material is 11% to 13%, Molding, the molding pressure is controlled to 30MP～50MP (the molding pressure in the process is 35MP), the diameter of the block is 3.6cm, and the corn stalk type block fuel is obtained.

(5) Extraction of humic acid: add concentrated hydrochloric acid to the filtrate obtained in step (3) to adjust the pH to less than 3 for acidification, stir for 10 minutes to obtain a dark brown precipitate, filter to obtain a dark brown solid that is humic acid. The supernatant can be reused in the step (2) as a hydrothermal reaction solution, or the process water for the preparation of the corn stalk block in the step (4).

(6) Production of humic acid sodium salt: heating, concentrating and drying the filtrate obtained in step (3) to obtain humic acid sodium salt.

Example 2:

The difference between this embodiment and Example 1 is that in step (2), 200ml of water is added to the hydrothermal reaction kettle, the temperature is raised after thorough stirring, and the reaction is carried out under hydrothermal conditions of 140, 160, 180, and 220°C for 3.0 hours respectively. Other processes are the same as in Example 1.

Example 3:

The difference between this embodiment and Example 1 is: in step (2), add 200ml of water into the hydrothermal reaction kettle, heat up after fully stirring, and react under 200°C hydrothermal conditions for 1.5, 2.0, 2.5, and 3.5 hours respectively. Other processes are the same as in Example 1.

Example 4:

The difference between this embodiment and Example 1 is that in step (2), 0.3 kg (dry basis) of straw powder is put into a polytetrafluoroethylene-lined reactor, and 6 L of water is added. Other processes are the same as in Example 1.

The yields of humic acid obtained in Examples 1-4 are shown in Table 1, and the calorific value, cold compressive strength and burnout rate of corn stalk blocks are shown in Table 2.

Table 1

Table 2

Claims (6)

1. a kind of method of the production of hydrothermal carbonization maize straw humic acid and type briquette fuel, it is characterised in that：With maize straw and Water is raw material, agitated mixing, and hydrothermal carbonization reaction occurs in hydrothermal reaction kettle, to hydrothermal carbonization product using alkali carries in situ Mode so that humic acid is completely converted into water-soluble sodium humate, obtain sodium humate solution and solid by filtering after reaction Body is carbonized filter residue, is acidified, is filtered to smoke filtrate, obtain humic acid, or is concentrated to smoke filtrate, dries and can be obtained Sodium humate, solid carbonization filter residue are mixed with fine coal, are molded, acquisition type briquette fuel.

2. the method for the production of hydrothermal carbonization maize straw humic acid and type briquette fuel described in accordance with the claim 1, feature exist In：The technique that humic acid is prepared using maize straw and water as raw material is hydrothermal carbonization reaction process.

3. the method for the production of hydrothermal carbonization maize straw humic acid and type briquette fuel described in accordance with the claim 1, feature exist In：The process of extracted humic acid is carried out in same reactor with alkali density, is added using alkali carries technique in situ, hydrothermal reaction process It is solid sodium hydroxide particle to enter alkali.

4. the method for the production of hydrothermal carbonization maize straw humic acid and type briquette fuel described in accordance with the claim 1, feature exist In：The process conditions of maize straw hydrothermal reaction process are：In terms of 10g over dry maize straws, the volume of water is 50~250ml, Hydrothermal carbonization temperature is 140~220 DEG C, and the hydrothermal carbonization time is 1.5~3.5 hours.

5. the method for the production of hydrothermal carbonization maize straw humic acid and type briquette fuel described in accordance with the claim 1, feature exist In：The preparation of maize straw type block is using maize straw carbonization filter residue and fine coal after hydro-thermal as raw material.

6. the method for the production of hydrothermal carbonization maize straw humic acid and type briquette fuel described in accordance with the claim 1, feature exist In：The mass ratio of maize straw hydrothermal carbonization filter residue and fine coal is 1 in the preparation process of maize straw type block：4~1：10.