CN107967238A - A kind of oxygen-containing baking process determination method for parameter for improving rice straw calorific value - Google Patents

Abstract

The invention discloses a method for determining parameters of an oxygen-containing roasting process for increasing the calorific value of rice stalks. The method of the present invention comprises steps: a. cleaning, drying and pulverizing the rice straw; b. roasting the treated rice straw in step a, and recording the roasting time when the solid mass is no longer changed; c. Cool the roasted product at a temperature not greater than 40°C in the same atmosphere as the roasting; d. Collect the product biochar obtained in step c, and weigh it and measure its calorific value; e. Process the data and establish According to the equation, the relationship between the roasting time, the mass yield of solid products, the calorific value of solid products, the roasting temperature and the oxygen content are respectively fitted, and the mathematical expressions are obtained. The invention can provide method and continuous data support for the actual production of biomass roasting.

Description

A method for determining the process parameters of oxygen-containing roasting to increase the calorific value of rice straw

Technical field:

The invention relates to a method for determining parameters of an oxygen-containing roasting process for increasing the calorific value of rice straw, and belongs to the technical field of energy and power.

Background technique:

At present, people's research on biomass roasting mainly examines the influence of individual temperature, atmosphere and other conditions on the product, and then obtains the qualitative relationship between roasting parameters and product physical parameters. This research method can only obtain the specific influence of individual baking conditions on the product, but cannot form a continuous and specific corresponding relationship. Therefore, the guidance for actual production is relatively limited.

Contents of the invention

The purpose of the present invention is to provide a method for determining parameters of an oxygen-containing roasting process for increasing the calorific value of rice straw, and to provide method and continuous data support for the actual production of biomass roasting.

The above-mentioned purpose is achieved through the following technical solutions:

A method for determining parameters of an oxygen-containing roasting process for increasing the calorific value of rice straw, the method comprising the following steps:

a. cleaning, drying and pulverizing the rice straw;

b. roasting the treated rice straw in step a, when the solid mass is no longer changed after roasting, record the roasting time;

c. Cool the roasted product at a temperature not higher than 40°C under the same atmosphere as the roasting;

d. collect the product biochar obtained in step c, and weigh and measure its calorific value;

e. Process the data, establish equations, respectively fit the relationship between the roasting time, solid product mass yield, solid product calorific value, roasting temperature, and oxygen content, and obtain mathematical expressions.

In the method for determining parameters of the oxygen-containing roasting process for increasing the calorific value of rice straw, the drying in step a is carried out at a temperature of 100°C to 110°C, and the drying time is 16-24h.

In the method for determining the parameters of the oxygen-containing roasting process for increasing the calorific value of rice straw, the pulverization in step a is to pulverize the rice straw to a particle diameter of 0.2-0.4 mm.

In the method for determining process parameters of oxygen-containing roasting for increasing the calorific value of rice straw, the roasting in step b is constant temperature roasting, and the roasting temperature is between 230°C and 310°C.

In the method for determining process parameters of oxygen-containing roasting for increasing the calorific value of rice straw, the roasting atmosphere in step b is carried out between 0% and 21% oxygen content (volume content).

In the method for determining process parameters of oxygen-containing roasting for increasing the calorific value of rice straw, the roasting described in step b is carried out at an air flow rate of 450ml/min-500ml/min.

In the method for determining the parameters of the oxygen-containing roasting process for increasing the calorific value of rice straw, when recording the roasting time in step b, the solid mass change rate is less than 0.1%/min as the recording point.

In the method for determining the parameters of the oxygen-containing roasting process for improving the calorific value of rice straw, the relationship between the roasting time, oxygen content and roasting temperature described in step e is:

y _t =6.5476×10 ^-4 T ² -1.2769T-0.00567Y _O2 ² +0.1077Y _O2 +353.99,

In the formula: y _t represents the roasting time, T represents the roasting temperature, Y _O2 represents the oxygen content.

In the method for determining the parameters of the oxygen-containing roasting process for increasing the calorific value of rice straw, the relationship between the solid product mass yield, oxygen content and roasting temperature described in step e is:

Y _m =0.005445Y _O2 ² -2.0687Y _O2 +0.00121T ² -0.95805T+227.8735,

In the formula: Y _m represents the mass yield of the solid product, that is, the percentage of the solid product mass to the initial solid mass, T represents the baking temperature, and Y _O2 represents the oxygen content.

In the method for determining the oxygen-containing roasting process parameters for increasing the calorific value of rice straw, the relationship between the calorific value of the solid product described in step e, the oxygen content and the roasting temperature is:

Y _H ＝-0.0061Y _O2 ² +0.03519Y _O2 -7.01488×10 ^-4 T ² +0.3554T-27.4960,

In the formula: Y _H represents the calorific value of the solid product, T represents the baking temperature, and Y _O2 represents the oxygen content.

Beneficial effect:

The equation constructed by the invention can well describe the relationship between the baking process parameters and the product physical parameters. The present invention can well provide reliable data reference and technical guidance for the practical application of biomass roasting. When rice straw is roasted at a certain temperature and oxygen content, it can be deduced according to the formula in claim 8 that the roasting time The required time, according to the formula in claim 9, deduce the quality of the solid product obtained, and deduce the product calorific value according to the formula in claim 10. Similarly, the appropriate temperature and oxygen content for baking can also be calculated from the formulas in claims 8, 9, and 10 according to the requirements for the calorific value of the product and the baking time.

Description of drawings

Fig. 1 is a process flow diagram of the present invention.

Fig. 2 is the variation trend with time of the mass yield of solid products described in various embodiments of the present invention.

Detailed ways

The present invention will be further illustrated below in conjunction with specific embodiments, and it should be understood that the following specific embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

The method for determining the technical parameters of oxygen-containing roasting for increasing the calorific value of rice straw according to the present invention comprises the following steps:

a. Washing the rice straw, drying it at a temperature of 100°C to 110°C, the drying time is 16-24h, and crushing to a particle size of 0.2-0.4mm;

b. The rice straw treated in step a is subjected to constant temperature roasting, the roasting temperature is between 230°C-310°C, and the oxygen content (volume content) is between 0% and 21%, and the roasting is carried out at an air flow rate of 450ml/min -500ml/min, when the rate of change of solid mass is less than 0.1%/min, record the baking time;

c. Cool the roasted product at a temperature not higher than 40°C under the same atmosphere as the roasting;

d. collect the product biochar obtained in step c, and weigh and measure its calorific value;

e. Use Origin software to draw the relationship diagram of roasting time, solid product mass yield, solid product calorific value, roasting temperature, and oxygen content, and establish a new y=ax ₁ ² +bx ₁ in the nonlinear fitting formula library of Origin +cx ₂ ² +dx ₂ +e formula, use this formula to fit the relationship between the roasting time, solid product mass yield, solid product calorific value, roasting temperature, and oxygen content, and get a, b, c in the formula , d, e values, and finally get the mathematical expression between the parameters.

The relational expression between baking time and oxygen content and baking temperature is:

y _t =6.5476×10 ^-4 T ² -1.2769T-0.00567Y _O2 ² +0.1077Y _O2 +353.99,

In the formula: y _t represents the roasting time, T represents the roasting temperature, Y _O2 represents the oxygen content.

The relational expression between described solid product mass yield and oxygen content and baking temperature is:

Y _m =0.005445Y _O2 ² -2.0687Y _O2 +0.00121T ² -0.95805T+227.8735,

In the formula: Y _m represents the mass yield of the solid product, that is, the percentage of the solid product mass to the initial solid mass, T represents the baking temperature, and Y _O2 represents the oxygen content.

The relational expression between described solid product calorific value and oxygen content and baking temperature is:

Y _H ＝-0.0061Y _O2 ² +0.03519Y _O2 -7.01488×10 ^-4 T ² +0.3554T-27.4960,

In the formula: Y _H represents the calorific value of the solid product, T represents the baking temperature, and Y _O2 represents the oxygen content.

Specific examples:

Example 1:

a. According to claim 8, 9, 10, calculate respectively 230 ℃ according to the fitting formula, the baking time under 0% oxygen content, solid product mass yield and solid product calorific value (calculation result is: time 94.9min, mass yield 71.53%, product calorific value 17.14MJ/kg).

b. Take 2g of rice straw, wash it, dry it at 100°C for 24 hours, and crush it to a particle size of about 0.3mm;

c. The rice straw treated in step a is subjected to constant temperature roasting, the roasting temperature is 230°C, and the oxygen content (volume content) is 0%, the roasting is implemented at an air flow rate of 500ml/min, and the products at different roasting times are recorded Yield, draw the change curve of product yield with time, record the time when the rate of change of solid mass is less than 0.1%/min after the curve is smoothed (record result: 92min);

d. Cooling the baked product at a temperature of 25° C. under the same atmosphere as that used for baking;

e. collect the product biochar obtained in step c, and weigh it and measure its calorific value (experimental results: the mass yield is 73.12%, and the product calorific value is 16.944MJ/kg);

Example 2:

a. According to claim 8, 9, 10, calculate respectively 310 ℃ according to the fitting formula, the baking time under 0% oxygen content, solid product mass yield and solid product calorific value (calculation result is: time 21.1min, mass yield 47.16%, product calorific value 15.27MJ/kg).

b. Take 2g of rice straw, wash it, dry it at 100°C for 24 hours, and crush it to a particle size of about 0.3mm;

c. The rice straw treated in step a is subjected to constant temperature roasting, the roasting temperature is 230°C, and the oxygen content (volume content) is 0%, the roasting is implemented at an air flow rate of 500ml/min, and the products at different roasting times are recorded Yield, draw the change curve of product yield with time, record the time when the rate of change of solid mass is less than 0.1%/min after the curve is smoothed (record result: 53min);

d. Cooling the baked product at a temperature of 25° C. under the same atmosphere as that used for baking;

e. collect the product biochar obtained in step c, and weigh it and measure its calorific value (experimental results: the mass yield is 45.22%, and the product calorific value is 16.014MJ/kg);

Example 3:

According to the fitting formula in claim 8, 9, 10, calculate respectively 230 ℃, the baking time under 21% oxygen content, solid product mass yield and solid product calorific value (calculation result is: time 94.7min, mass yield 52.10%) , product calorific value 15.19MJ/kg).

b. Take 2g of rice straw, wash it, dry it at 100°C for 24 hours, and crush it to a particle size of about 0.3mm;

c. The rice straw treated in step a is subjected to constant temperature roasting, the roasting temperature is 230°C, and the oxygen content (volume content) is 0%, the roasting is implemented at an air flow rate of 500ml/min, and the products at different roasting times are recorded Yield, draw the change curve of product yield with time, record the time when the rate of change of solid mass is less than 0.1%/min after the curve is smoothed (record result: 110min);

d. Cooling the baked product at a temperature of 25° C. under the same atmosphere as that used for baking;

e. collect the product biochar obtained in step c, and weigh it and measure its calorific value (experimental results: the mass yield is 52.16%, and the product calorific value is 15.944MJ/kg);

Example 4:

According to the fitting formula in claim 8, 9, 10, calculate respectively 230 ℃, the baking time under 21% oxygen content, solid product mass yield and solid product calorific value (calculation result is: time 20.83min, mass yield 52.10%) , product calorific value 27.73MJ/kg).

b. Take 2g of rice straw, wash it, dry it at 100°C for 24 hours, and crush it to a particle size of about 0.3mm;

c. The rice straw treated in step a is subjected to constant temperature roasting, the roasting temperature is 230°C, and the oxygen content (volume content) is 0%, the roasting is implemented at an air flow rate of 500ml/min, and the products at different roasting times are recorded Yield, draw the change curve of product yield with time, record the time when the rate of change of solid mass is less than 0.1%/min after the curve is smoothed (record result: 25min);

d. Cooling the baked product at a temperature of 25° C. under the same atmosphere as that used for baking;

e. collect the product biochar obtained in step c, and weigh it and measure its calorific value (experimental results: the mass yield is 28.12%, and the product calorific value is 12.72MJ/kg);

Example 5:

According to the fitting formula in claim 8, 9, 10, respectively calculate 230 ℃, the baking time under 21% oxygen content, solid product mass yield and solid product calorific value (calculation result is: time 75.96min, mass yield 44.83% , product calorific value 16.51MJ/kg).

b. Take 2g of rice straw, wash it, dry it at 100°C for 24 hours, and crush it to a particle size of about 0.3mm;

c. The rice straw treated in step a is subjected to constant temperature roasting, the roasting temperature is 230°C, and the oxygen content (volume content) is 0%, the roasting is implemented at an air flow rate of 500ml/min, and the products at different roasting times are recorded Yield, draw the change curve of product yield with time, record the time when the rate of change of solid mass is less than 0.1%/min after the curve is smoothed (record result: 90min);

d. Cooling the baked product at a temperature of 25° C. under the same atmosphere as that used for baking;

e. collect the product biochar obtained in step c, and weigh it and measure its calorific value (experimental results: the mass yield is 45%, and the product calorific value is 17.14MJ/kg);

It should be pointed out that the above-mentioned implementation example is only to prove the correctness of the prediction of the rice straw baking process by the present invention, and to clearly illustrate the example, but not to limit the implementation mode. The method is exhaustive. All components that are not specified in this embodiment can be realized by existing technologies. For those skilled in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims (10)

1. A method for determining an oxygen-containing roasting process parameter for improving the calorific value of rice straw, characterized in that the method comprises the steps of: a. cleaning, drying and pulverizing the rice straw; b. roasting the treated rice straw in step a, when the solid mass is no longer changed after roasting, record the roasting time; c. Cool the roasted product at a temperature not higher than 40°C under the same atmosphere as the roasting; d. collect the product biochar obtained in step c, and weigh and measure its calorific value; e. Process the data, establish equations, respectively fit the relationship between the roasting time, solid product mass yield, solid product calorific value, roasting temperature, and oxygen content, and obtain mathematical expressions. 2. The method for determining the process parameters of oxygen-containing roasting for increasing the calorific value of rice straw according to claim 1, characterized in that, the drying described in step a is carried out at a temperature of 100°C to 110°C, and the drying time is 16 -24h. 3. The method for determining process parameters of oxygen-containing roasting for increasing the calorific value of rice straw according to claim 1, characterized in that the pulverization in step a is to pulverize the rice straw to a particle diameter of 0.2-0.4mm. 4. The method for determining process parameters of oxygen-containing roasting for increasing the calorific value of rice straw according to claim 1, characterized in that the roasting in step b is constant temperature roasting, and the roasting temperature is between 230°C and 310°C. 5. The method for determining the oxygen-containing roasting process parameters for increasing the calorific value of rice straw according to claim 1, wherein the roasting atmosphere described in step b is between 0% and 21% of the oxygen content (volume content) in between. 6. The method for determining process parameters of oxygen-containing roasting for increasing the calorific value of rice straw according to claim 1, characterized in that the roasting in step b is carried out at an air flow rate of 450ml/min-500ml/min. 7. The method for determining the oxygen-containing roasting process parameters for increasing the calorific value of rice straw according to claim 1, characterized in that, when recording the roasting time described in step b, the rate of change of solid mass is less than 0.1%/min. record point. 8. the determination method of the oxygen-containing roasting process parameter that improves rice straw calorific value according to claim 1, is characterized in that, the relational expression between the roasting time described in step e and oxygen content and roasting temperature is: y _t =6.5476×10 ^-4 T ² -1.2769T-0.00567Y _O2 ² +0.1077Y _O2 +353.99, In the formula: y _t represents the roasting time, T represents the roasting temperature, Y _O2 represents the oxygen content. 9. The method for determining the oxygen-containing roasting process parameters for increasing the calorific value of rice straw according to claim 1, characterized in that the relationship between the solid product mass yield, oxygen content and roasting temperature described in step e for: Y _m =0.005445Y _O2 ² -2.0687Y _O2 +0.00121T ² -0.95805T+227.8735, In the formula: Y _m represents the mass yield of the solid product, that is, the percentage of the solid product mass to the initial solid mass, T represents the baking temperature, and Y _O2 represents the oxygen content. 10. The method for determining the oxygen-containing roasting process parameters for increasing the calorific value of rice straw according to claim 1, wherein the relational expression between the calorific value of the solid product described in step e, the oxygen content and the roasting temperature is: : Y _H =-0.0061Y _O2 ² +0.03519Y _O2 -7.01488×10 ^-4 T ² +0.3554T-27.4960, where Y _H represents the calorific value of the solid product, T represents the baking temperature, and Y _O2 represents the oxygen content.