WO2017071025A1

WO2017071025A1 - Preparation method and usage method of inhibitor for preventing spontaneous combustion of dry lignite

Info

Publication number: WO2017071025A1
Application number: PCT/CN2015/098038
Authority: WO
Inventors: 吴国光; 孟献梁; 褚睿智; 刘晖
Original assignee: 中国矿业大学
Priority date: 2015-10-29
Filing date: 2015-12-21
Publication date: 2017-05-04
Also published as: CN105419818B; CN105419818A

Abstract

Provided are a preparation method and a usage method of an inhibitor for preventing the spontaneous combustion of dry lignite, belonging to preparation methods and usage methods of an inhibitor for preventing the spontaneous combustion of coal. A component (A) of the inhibitor accounting for 60-80 wt% is a main inhibitor, and a component (B) of the inhibitor accounting for 20-40 wt% is a secondary inhibitor. The preparation method comprises: (1) preparing a sample; (2) preparing the secondary inhibitor at a certain temperature; (3) uniformly mixing to form an inhibitor powder; (4) weighing the inhibitor powder and water and thoroughly mixing same in a weight ratio of 1 : 1-8 to obtain an inhibitor solution; and (5) by the mass-volume ratio, uniformly spraying the inhibitor solution onto the surface of a coal sample in a ratio of 1 : 0.1-2.0. In a water evaporation stage, compared with raw dry lignite, the activation energy of the inhibited coal sample after being sprayed with the inhibitor solution is improved by 25% or more; in an oxygen absorbing oxidation stage, compared with the raw dry lignite, the activation energy is improved by 170% or more; the critical temperature for spontaneous combustion of the lignite can be increased to 136°C or more from about 75°C for the raw lignite, and thus the inhibition effect is significant. The inhibitor is economical, creates no pollution, is convenient to transport, simple to use and convenient to operate.

Description

Preparation method and use method of inhibitor for preventing dry lignite spontaneous combustion

Technical field

The invention relates to a preparation method and a use method for preventing coal spontaneous combustion inhibitor, in particular to a preparation method and a use method for preventing a self-ignition of dry brown coal.

Background technique

China's coal resources are abundant, and its output and consumption rank first in the world. It is a key driving resource for China's rapid economic development. In the process of coal production, transportation and storage, oxidative spontaneous combustion occurs frequently, and it is not easy to be discovered in the early stage of spontaneous combustion.

China's largest coal reserves have been found to be lignite, accounting for about 17% of the country's coal reserves. Lignite is a low-grade coal. Due to its high oxygen content, high porosity, high volatile content and strong reactivity, it is becoming the main coal in the field of clean coal utilization such as power generation, pyrolysis, gasification and liquefaction. Because of these characteristics, lignite has a high tendency to spontaneous combustion, and it is highly prone to oxidation in the air, eventually leading to spontaneous combustion.

At present, fire prevention technology mainly includes water injection grouting, filling with inert gas, adding inhibitor, equalizing plugging, foam and colloidal fire prevention. The above fire prevention technologies have their own characteristics. Among them, the use of inhibitors to prevent coal spontaneous combustion is a commonly used fire prevention technology. Generally speaking, the main inhibitory effect of inhibitors on coal is physical, and some chemical reactions occur at the same time. The reaction is low in cost, simple in operation and good in resistive effect, and is widely recognized and applied. Each of the inhibitors has its advantages and limitations, and its mechanism of action and effects are also different.

At present, there is blindness in the selection of inhibitors in China, which cannot effectively solve the problem of self-ignition of coal types.

Summary of the invention

The object of the present invention is to provide a preparation method and a use method of a resisting agent for preventing spontaneous combustion of dry lignite, the inhibitor has the following effects: 1 obvious effect, long resistive life; 2 non-toxic and non-polluting, no harm to human health , does not damage the environment; 3 easy to produce, low cost of raw materials, easy to use; 4 pairs of equipment without corrosion.

The object of the present invention is achieved by the method for preparing the inhibitor of the present invention; the inhibitor comprises the component (A) and the component (B), and the specific steps are as follows:

(1) Sample preparation: the lignite is stripped of the surface oxide layer, followed by rapid crushing, and a sufficient amount of coal sample having a size of 1 mm < particle size < 4 mm is sieved;

(2) Add phosphoric acid to a three-necked flask, heat up, add a metered amount of urea (8:9 molar ratio with phosphoric acid) while stirring, and control the temperature not to exceed 80 °C. After the urea is completely dissolved, the solution is further heated, and a white solid, that is, an ammonium polyphosphate, is obtained through three stages of foaming, polymerization, and solidification. The generated gas is condensed by reflux, washed with water and then absorbed with a 1.0 mol/L sodium hydroxide solution;

(3) by mass, component (A) is 60-80% by weight of primary inhibitor, component (B) is 20-40% by-product; uniformly mixing it into inhibitor powder;

(4) The inhibitor powder and water are sufficiently mixed to form a inhibitor solution in a ratio of 1-5:5 by weight.

Specific steps of the method of use of the present invention: g gas sample / ml resistive solution, a 1:0.1-2.0 ratio of the resistive solution is evenly sprayed on the surface of the coal sample.

The primary inhibitor is magnesium chloride.

The secondary inhibitor is obtained by mixing ammonium dihydrogen phosphate and ammonium polyphosphate in a mass ratio of 1:1 to 2.

The secondary retarding agent ammonium polyphosphate is obtained by synthesizing phosphoric acid and urea, and the controlled temperature during synthesis is not more than 80 ° C, and the synthesized gas is absorbed by the sodium hydroxide solution. The molar ratio of phosphoric acid to urea is 8:9.

The beneficial effects, due to the adoption of the above scheme, the experimental determination by the thermogravimetric analyzer confirmed that the coal water activation activation energy and the ignition activation energy were significantly improved, and the ignition point was increased to above 130 ° C, and the resistance effect was remarkable. The inhibitor is economical, non-polluting, convenient to transport, and simple to use; at the same time, the spraying is simple and easy to operate.

(1) The activation energy of the resistive coal sample in the water evaporation stage is 38.21kJ/mol, which is 25.4% higher than the original coal of 30.48kJ/mol; the activation energy in the oxygen oxidation stage is 2.97kJ/mol, which is better than the raw coal. 3.56kJ/mol is 183.4% higher. That is, the self-ignition critical temperature of the lignified lignite is increased from 75 ° C to 132 ° C.

(2) The inhibitor is harmless to the human body, and is less irritating to human skin and mucous membranes of the eyes. Therefore, the dusting agent is safe for the human body.

(3) The inhibitor is almost non-corrosive to the equipment.

(4) The inhibitor has low cost, is easy to use, and is easy to store.

detailed description

The preparation method of the inhibitor of the present invention, the inhibitor comprises the component (A) and the component (B); the specific steps are as follows:

(2) Adding phosphoric acid to a three-necked flask, heating and heating, adding a metered urea (8:9 molar ratio to phosphoric acid) with a molar ratio of 8:9 while stirring, and controlling the temperature not to exceed 80 °C. After the urea is completely dissolved, the solution is further heated, and a white solid, that is, an ammonium polyphosphate, is obtained through three stages of foaming, polymerization, and solidification. The generated gas is condensed by reflux, washed with water and then absorbed with a 1.0 mol/L sodium hydroxide solution;

The specific steps of the method of the invention are as follows: g gas sample/ml resistive solution according to mass to volume ratio, and a 1:0.1-2.0 ratio of the resistive solution is evenly sprayed on the surface of the coal sample.

The activation energy of the resistive coal sample after spraying the resistive solution is more than 25% higher than that of the original dry lignite. The activation energy in the oxygen oxidation stage is more than 170% higher than that of the original dry lignite. The critical temperature of lignite spontaneous combustion can be from the raw coal. Increasing to about 136 ° C at around 75 ° C, the resistance effect is significant.

The primary inhibitor is magnesium chloride.

The invention relates to a resisting agent for preventing self-ignition of coal. When a resisting agent is added to the water to be arranged as a resistive solution, and sprayed on the coal pile in proportion, the coal can be prevented from spontaneous combustion.

Example 1:

(1) Sample preparation: the lignite is stripped of the surface oxide layer, followed by rapid crushing, and sieved out a sufficient amount of 1 mm<grain <4mm coal sample.

(2) The phosphoric acid added to the three-necked flask is heated and heated, and the metered urea is added (with a molar ratio of 8:9 to the phosphoric acid) while stirring, and the controlled temperature is not more than 80 °C. After the urea is completely dissolved, the solution is further heated, and a white solid, that is, an ammonium polyphosphate, is obtained through three stages of foaming, polymerization, and solidification. The generated gas is condensed by reflux, washed with water and then absorbed with a 1.0 mol/L sodium hydroxide solution;

(3) Component (A) is 60% of the primary inhibitor and component (B) is 40% by weight of the catalyst. Mix it evenly into a inhibitor powder;

(4) taking the inhibitor powder and water in a ratio of 2:5 by weight to thoroughly mix into a resist agent solution;

(5) 1 g of the coal sample and 0.3 mL of the inhibitor solution are uniformly mixed;

(6) Applying a thermogravimetric analyzer, and determining experimental conditions;

(7) determining the coal sample starting temperature is T ₀ and the water loss end point temperature T ₁ ;

(8) Finally, based on the calculated dehydration end point temperature and the increase in ignition activation energy.

2, resistance effect

The critical temperature of coal sample reached 79 °C, the cracking temperature reached 139 °C, and the resistive coal sample had a good resisting effect, which obviously delayed the evaporation process of water, and the water evaporation phase in the low temperature oxidation process prolonged. The activation energy of the resistive coal sample in the water evaporation stage is 39.47kJ/mol, which is 29.5% higher than the original coal of 30.48kJ/mol; the activation energy in the oxygen oxidation stage is 2.84kJ/mol, which is -3.56kJ/ of the raw coal. The mol is 179.7% higher. That is, the self-ignition critical temperature of the lignified lignite is increased from 75 ° C to 140 ° C.

Example 2:

(1) Sample preparation: The lignite is stripped of the surface oxide layer, followed by rapid crushing, and a sufficient amount of coal sample having a particle size of 1 mm < particle size < 4 mm is sieved.

(3) Component (A) is 70% of the main inhibitor, and component (B) is 30% by weight of the catalyst. Put it

Evenly mixed into a inhibitor powder;

(4) taking the inhibitor powder and water in a ratio of 4:5 by weight to fully mix into a resist agent solution;

(5) 1 g of the coal sample and 0.4 mL of the inhibitor solution are uniformly mixed;

2, resistance effect

The critical temperature of the coal sample reached 73 °C, and the cracking temperature reached 122 °C. The resistive coal sample had a good resisting effect, which obviously delayed the evaporation process of water, and the water evaporation phase in the low temperature oxidation process prolonged. The activation energy of the resistive coal sample in the water evaporation stage is 32.18kJ/mol, which is 5.6% higher than the original coal of 30.48kJ/mol; the activity in the oxygen oxidation stage The chemical energy is 2.47kJ/mol, which is 169.4% higher than the original coal of -3.56kJ/mol. That is, the critical temperature of self-ignition of lignite that has been resisted is increased from 77 ° C to 132 ° C.

Example 3:

(1) Sample preparation: The lignite is stripped of the surface oxide layer, followed by rapid crushing, and a coal sample of a sufficient amount of particle size is sieved.

(3) Component (A) is 80% by mass of the main inhibitor, and component (B) is 20% by weight of the catalyst. Mix it evenly into a inhibitor powder;

(4) taking the inhibitor powder and water in a ratio of 3:5 by weight to fully mix into a resist agent solution;

(5) 1 g of coal sample and 0.5 mL of the inhibitor solution are uniformly mixed;

2, resistance effect

The critical temperature of the coal sample reached 84 ° C, the cracking temperature reached 100 ° C, and the resistance of the coal sample was blocked. The activation energy of the resistive coal sample in the water evaporation stage is 42.15kJ/mol, which is 19.5% higher than the original coal of 30.48kJ/mol; the activation energy in the oxygen oxidation stage is 2.65kJ/mol, which is -3.56kJ/ of the raw coal. The mol is 174.4% higher. That is, the critical temperature of self-ignition of lignite that has been resisted is increased from 72 ° C to 136 ° C.

Practical Example 4: 25 kg of a blocking agent was added to 100 kg of water which was stirred at a high speed, and the mixture was stirred slowly, and was set as a resistive solution. Spray the solution evenly on 50L:100kg on the Xiaolongtan lignite pile and mix thoroughly. During the coal storage and storage period, the coal pile low temperature oxidation temperature and the marker gas concentration coupling measuring device are used to monitor the internal temperature and gas concentration changes of the coal pile to determine whether the coal pile has the possibility of spontaneous combustion; the coal pile can be placed for one hundred days. No spontaneous combustion occurs.

The activation energy of the resistive coal sample in the water evaporation stage is 38.21kJ/mol, which is 25.4% higher than the original coal of 30.48kJ/mol; the activation energy in the oxygen oxidation stage is 2.97kJ/mol, which is -3.56kJ/ of the raw coal. The mol is 183.4% higher. That is, the self-ignition critical temperature of the lignified lignite is increased from 75 ° C to 130 ° C.

Claims

A preparation method and a use method for preventing a self-ignition of dry brown coal, characterized in that: a preparation method of a inhibitor, the inhibitor comprises component (A) and component (B); the specific steps are as follows:

(1) Sample preparation: the lignite is stripped of the surface oxide layer, followed by rapid crushing, and a sufficient amount of coal sample having a size of 1 mm < particle size < 4 mm is sieved;

(2) Add phosphoric acid to a three-necked flask, heat up, add a metered amount of urea (8:9 molar ratio to phosphoric acid) with stirring, and control the temperature not to exceed 80 °C. After the urea is completely dissolved, the solution is further heated, and a white solid, that is, an ammonium polyphosphate, is obtained through three stages of foaming, polymerization, and solidification. The generated gas is condensed by reflux, washed with water and then absorbed with a 1.0 mol/L sodium hydroxide solution;

(3) by mass, component (A) is 60-80% by weight of primary inhibitor, component (B) is 20-40% by-product; uniformly mixing it into inhibitor powder;

(4) The inhibitor powder and water are sufficiently mixed to form a inhibitor solution in a ratio of 1-5:5 by weight.
The method for preparing a resisting agent for preventing spontaneous combustion of dry lignite according to claim 1, wherein the primary inhibitor is magnesium chloride.
The method for preparing a resisting agent for preventing spontaneous combustion of dry lignite according to claim 1, wherein the auxiliary inhibitor is ammonium dihydrogen phosphate and ammonium polyphosphate, and is 1:1 by mass. 2 mixed.
The method for preparing a resisting agent for preventing spontaneous combustion of dry lignite according to claim 1, wherein the auxiliary retarding agent ammonium polyphosphate is obtained by synthesizing phosphoric acid and urea, and the temperature is not controlled during the synthesis. Above 80 ° C, the synthetic gas is absorbed by the sodium hydroxide solution; the molar ratio of phosphoric acid to urea is 8:9.
The invention discloses a method for using a resisting agent for preventing spontaneous combustion of dry lignite, characterized in that: in a mass-to-volume ratio, g coal sample/ml resisting solution, uniformly spraying a resisting solution of a ratio of 1: (0.1-2.0) on coal The surface can be.