JP6988652B2 - Coal oxidation reaction test equipment and method for measuring water content dependence of coal oxidation reaction using this - Google Patents

Description

The present invention relates to a coal oxidation reaction test apparatus and a method for measuring the water content dependence of the coal oxidation reaction using the same, and more specifically, regarding a coal oxidation reaction that leads to coal oxidation heat generation and spontaneous ignition. , Suitable test equipment and measuring method for measuring the dependence of the water content.

Traditionally, when coal is stored in an outdoor coal storage yard or indoor storage facility, it reacts with oxygen in the atmosphere to generate heat and store heat, eventually causing spontaneous combustion. There is a problem such as. In particular, it is known that low-grade coal such as subbituminous coal and lignite is likely to react with oxygen due to its molecular structure and physical structure, and when such low-grade coal is used. In addition, it is necessary to take preventive measures against the problem of spontaneous combustion as described above.

In order to prevent spontaneous combustion of coal, it is important to predict the exothermic behavior in the coal layer during storage. In order to make the prediction without cost and time, a simulation considering coal oxidation reaction, water absorption / desorption, or flow inside the coal layer is preferably used, and coal oxidation reaction has been carried out so far. -Although various efforts have been made to predict spontaneous combustion (see, for example, Patent Documents 1 and 2 and Non-Patent Documents 1 to 3), it has become a real phenomenon especially in a relatively low temperature region of 100 ° C. or lower. At present, a detailed model that matches has not been obtained yet. In other words, the ease of oxidation reaction of coal is strongly correlated with the amount of water contained in coal from the presumption that water acts as a catalyst in oxidation (the optimum amount of water at which oxidation reaction is likely to occur is the optimum amount of water). It is said that it exists), and it is also known that the tendency of the oxidation reaction changes with the passage of time from the speculation that the active site of the oxidation reaction is lost by oxidation. In order to simulate the oxidation reaction of coal with high accuracy, it is necessary to quantitatively evaluate the relationship (dependency) with the water content, but the above-mentioned Patent Documents 1 and 2 and Non-Patent Documents 1 and 2 are described above. In 2, none of them is a method that focuses on the water content of coal, or rather, it is decided to use dry coal in which water is removed from coal, and in those methods and measuring devices, coal is used. It is difficult to grasp the relationship / tendency between the water content of coal and the oxidation reaction. On the other hand, in Non-Patent Document 3, although the reactivity is verified by focusing on the water content of coal, it takes a long time because an experimental system is constructed in which dry gas is supplied. When the oxidation reaction is carried out, the water content of the coal may change due to the supply of the dry gas, and it becomes difficult to accurately grasp the relationship between the water content of the coal and the oxidation reaction.

Japanese Patent No. 3939989 Japanese Unexamined Patent Publication No. 2014-126541

Park Ocean et al. (2014). "Spontaneous Combustion Prediction Method in Subbituminous Coal Pile" "Kobe Steel Technique", Vol.64 No.1, 22-27. Haihui Wang et al., “Experimental Study on Low-Temperature Oxidation of an Australian Coal”, Energy & Fuels 1999, 13, 1173-1179 X Dong Chen et al., “The effect of moisture content on the oxidation rate of coal during near-equilibrium drying and wetting at 50 ℃”, Fuel 1993, Volume 72 No.6, 787-792

By the way, a solid containing coal generally has a property that the water content is settled to a constant level when it is placed in a constant humidity environment. The present inventors pay attention to such a property, and when verifying the relationship between the water content of coal and the oxidation reaction rate, a method of continuously supplying a gas (humidity control gas) whose relative humidity is adjusted in advance to coal. Was completed. At that time, in order to quantify the oxidation reaction of coal, it is performed by analyzing the gas consumed or generated by the oxidation reaction, but according to the prior verification by the present inventor, the coal can be used. If the amount of humidity control gas supplied is large, the amount of change in gas consumed or generated will be relatively small, making it impossible to perform accurate gas analysis. It was found that the amount of wet gas should be reduced as much as possible. Furthermore, in order to accurately adjust the relative humidity of such a gas with a small supply amount, for example, it has been found that it is difficult to adopt a method of applying a small amount of steam, and the relative humidity of the gas can be accurately adjusted. It turns out that a method of arbitrary adjustment is needed.

The present invention has been made in view of the above problems and findings, and it is possible to easily produce a humidity control gas in which the relative humidity is adjusted, and by using the humidity control gas, a long time is required. A coal oxidation reaction test device that can easily and accurately measure the relationship between the water content of coal and its oxidation reaction, and the measurement of the water content dependence of the coal oxidation reaction using this. The purpose is to provide a method.

That is, the gist of the present invention is as follows.
(1) A device for evaluating the water content dependence of the oxidation reaction of coal by analyzing the gas consumed or generated by the oxidation reaction.
A gas supply line including an inert gas line for supplying a dry inert gas and an oxygen-containing gas line for supplying a dry oxygen-containing gas, and a gas supply line.
A dry gas line capable of supplying the dry gas supplied from the gas supply line at an arbitrary flow rate via a flow rate adjusting mechanism, and a dry gas line.
The humidity control gas line and the inside can be supplied as a humidity control gas adjusted to a predetermined relative humidity via a humidifier that humidifies the dry gas of the dry gas line by bubbling it in water in which a non-volatile solute is saturated and dissolved. With a reactor in which coal is filled and the humidity control gas from the humidity control gas line is introduced.
A gas analyzer for analyzing the gas discharged from this reactor, and
Equipped with constant temperature equipment that can adjust the temperature
At least, the dry gas line, the humidifier, the humidity control gas line and the reactor are housed in the constant temperature facility, and the coal oxidation reaction test apparatus.
(2) Described in (1), the present invention is provided with a humidity measuring device capable of independently measuring the relative humidity of the humidity control gas supplied to the reactor and the relative humidity of the gas discharged from the reactor. Coal oxidation reaction test equipment.
(3) The coal oxidation reaction test according to (1) or (2), wherein the gas supply line is provided with a switching mechanism capable of switching between the inert gas line and the oxygen-containing gas line. Device.
(4) The coal oxidation according to any one of (1) to (3), wherein the humidifier includes a mechanism for supplying water in which non-volatile solute is saturated and dissolved, and a mechanism for discharging the water. Reaction test equipment.
(5) Any one of (1) to (4), characterized in that a dehumidifying mechanism for removing water vapor contained in the gas discharged from the reactor is provided between the reactor and the gas analyzer. The coal oxidation reaction test apparatus according to the section.
(6) When using a gas analyzer capable of measuring water vapor, it is characterized by being provided with a dew condensation prevention mechanism that keeps the piping between the reactor and the gas analyzer higher than the temperature of the constant temperature facility (1) to (1). The coal oxidation reaction test apparatus according to any one of 4).

(7) A method for measuring the water content dependence of the coal oxidation reaction using the coal oxidation reaction test apparatus according to any one of (1) to (6) above, wherein the constant temperature facility is used. After adjusting the temperature to the specified temperature
i) The process of humidifying the dried inert gas with a humidifier to generate a humidity control gas that has been adjusted to a predetermined relative humidity in advance.
ii) This generated humidity control gas is supplied into a reactor filled with coal, and the relative humidity of the gas supplied to the reactor is the same as the relative humidity of the gas discharged from the reactor. The process of keeping the water content of coal constant until it becomes
iii) Under the state where the water content of coal is kept constant by the step of ii), the oxygen-containing gas conditioned in the reactor is supplied to the reactor by switching the inert gas to the oxygen-containing gas, and the coal is used. And the process of initiating the oxidation reaction of
iv) A method for measuring the water content dependence of a coal oxidation reaction, which comprises a step of analyzing the gas discharged from the reactor after starting the coal oxidation reaction.
(8) The method for measuring the water content dependence of the oxidation reaction of coal according to (7), further comprising a step of removing water vapor contained in the gas discharged from the reactor.

According to the present invention, even in a relatively low temperature region of 100 ° C. or lower, the relationship between the water content of coal and its oxidation reaction can be observed over a long period of time through gas analysis that is consumed or generated by the oxidation reaction. It can be carried out easily and accurately. This can contribute to the modeling and simulation of the oxidation reaction of coal.

FIG. 1 is a schematic explanatory view of a coal oxidation reaction test apparatus according to the present invention. FIG. 2 is a graph showing the results of measuring the equilibrium water content of the coal (bituminous coal) used in Example 1. FIG. 3 is a graph showing the results of measuring the relative humidity of the gas before and after the reactor when the water content was adjusted before the start of the reaction in Example 1. FIG. 4 is a graph showing the results of measuring the concentrations (ppm) of carbon _{dioxide (CO 2} ) and carbon monoxide (CO) produced in the coal oxidation reaction carried out in Example 1 for each elapsed time. FIG. 5 is a graph showing the results of measuring the concentrations (ppm) of carbon _{dioxide (CO 2} ) and carbon monoxide (CO) produced in the coal oxidation reaction carried out in Comparative Example 1 for each elapsed time.

Hereinafter, an example of the coal oxidation reaction test apparatus according to the present invention will be shown in FIG. 1 described later, and the details will be described accordingly.
First, as the gas used in the present invention, at least an inert gas and an oxygen-containing gas in which the inert gas and the oxygen gas are mixed are used, and the oxygen-containing gas is supplied as shown in FIG. 1, respectively. It has an oxygen-containing gas line 1 and an inert gas line 2 capable of supplying an inert gas, and has a gas supply line 4 in which these are integrated. The gas supply line 4 may also have a switching mechanism (not shown) for switching between the oxygen-containing gas and the inert gas. As the inert gas, nitrogen, argon, helium or the like can be used. It is preferable to use a dried gas as the gas to be used.

Inert gas or oxygen-containing gas (hereinafter, this may be simply referred to as “dry gas”) is supplied from the gas supply line 4, but in the present invention, the gas supply line 4 supplies the gas. The dry gas is supplied to the dry gas line 6 via the flow rate adjusting mechanism 5 capable of adjusting the gas flow rate, and the relative humidity is adjusted by the humidifier 7 provided after this, so that the relative humidity is adjusted. Is connected to the humidity control gas line 9 as the adjusted humidity control gas.

Here, as the humidifier 7 in the present invention, a humidifier 7 is used in which a predetermined amount of a saturated aqueous solution in which a non-volatile solute is saturated and dissolved in water is sealed in a container or the like made of a heat-resistant material. This mechanism utilizes the principle of vapor pressure drop by dissolving a non-volatile solute, and the relative humidity is determined to be a different value depending on the type and temperature of the non-volatile solute to be dissolved. By aerating a dry gas through the humidifier 7 and bubbling it, a humidity control gas having an adjusted relative humidity can be obtained. As the non-volatile solute used, either an inorganic salt or an organic salt can be used. For example, as the inorganic salt, a halide salt composed of a metal such as an alkali metal or an alkaline earth metal and a halide is used. Hydroxide salts, carbonates, nitrates, sulfates, chromates and the like containing similar metals can be mentioned, and examples of the organic salts include acetates and citrates containing the above metals. Specifically, as described in JIS A 1475, cesium fluoride, lithium bromide, zinc bromide, potassium hydroxide, sodium hydroxide, lithium chloride, calcium bromide, lithium iodide, potassium acetate, Potassium Phosphate, Magnesium Chloride, Sodium Isolation, Potassium Carbonate, Magnesium Nitrate, Sodium Bromide, Cobalt Chloride, Potassium Isolate, Strontium Chloride, Sodium Nitrate, Sodium Chloride, Potassium Bromide, Ammonium Sulfate, Potassium Chloride, Strontium Nitrate, Sulfate Potassium, potassium chromate, zinc chloride, calcium nitrate and the like can be mentioned. Those in which these non-volatile solutes are dissolved in water at a saturated solubility or higher can be used at each temperature of use. Further, such a humidifier 7 may be provided with a mechanism for supplying water or water saturated and dissolved in a non-volatile solute (for example, a water supply line 16) and a mechanism for discharging the water (for example, a drainage line 17). preferable.

Then, in the oxidation reaction test apparatus of the present invention, by using the humidifier 7, a humidity control gas whose relative humidity is arbitrarily adjusted is generated (humidity control gas line 9), which is described later in the reactor 10. Introduced within. Further, a thermo-hygrometer 13 capable of measuring the temperature and humidity of the gas may be provided in the middle of the humidity control gas line 9.

By introducing the humidity control gas in which the relative humidity is arbitrarily adjusted into the reactor 10 filled with the coal 11, the water content of the filled coal can be kept constant. As the reactor 10, any container or the like made of a heat-resistant material can be used, in which the capacity or the like is appropriately changed according to the object of the present invention. Here, in order to confirm that the water content of coal is constant, the relative humidity of the humidity control gas introduced into the reactor may be compared with the relative humidity of the gas after passing through the reactor. For example, when a humidity control gas is introduced into dry coal, the water vapor in the gas is adsorbed on the coal and the relative humidity of the gas discharged from the reactor temporarily decreases, but by continuing for a sufficient period of time, The relative humidity of the humidity control gas introduced into the reactor and the relative humidity of the gas discharged from the reaction come to match, and it can be considered that the water content of the coal is constant. By performing this step using an inert gas before the start of the oxidation reaction while appropriately adjusting the temperature (temperature of the constant temperature facility 15) and the non-volatile solute used, the water content of the coal at the start of the oxidation reaction can be determined. It can be adjusted to a predetermined value.

Then, in the oxidation reaction test apparatus of the present invention, in particular, in order to enable long-term supply to coal while keeping the relative humidity of the humidity control gas constant at a set value, at least a dry gas line is used. 6. The humidifier 7, the humidity control gas line 9 and the reactor 10 (coal 11) all need to be placed at the same temperature. In order to realize this, as shown in FIG. 1, it is necessary that these facilities are housed in a constant temperature facility 15 capable of isothermal temperature. The temperature of the constant temperature facility 15 can be appropriately adjusted according to the temperature of the oxidation reaction to be carried out (for example, up to about 100 ° C.).

As described above, after confirming that the water content of the coal 11 is constant by measuring the relative humidity before and after the reactor 10, the gas from the gas supply line 4 is oxygenated while maintaining the operation so far. By switching to the contained gas, the introduction of the humidity-controlled oxygen-containing gas into the reactor 10 (coal 11) is started, and the oxidation reaction of the coal 11 is started. Here, from the viewpoint of improving the measurement accuracy, it is necessary to set the flow rate of the oxygen-containing gas in the oxidation reaction to a flow rate that is small enough not to affect the concentration measurement of the gas consumed or generated in the oxidation reaction. Therefore, it can be appropriately changed and carried out according to the conditions of the oxidation reaction, the amount of coal used, and the like.

After the oxidation reaction of the coal 11 is started, the gas discharged from the reactor 10 is analyzed by the gas analyzer 14. When water vapor cannot be measured by the gas analyzer 14, it is preferable that the reactor 10 and the gas analyzer 14 are provided with a dehumidifying mechanism (water vapor trap) 18 for removing water vapor contained in the discharged gas. As the dehumidifying mechanism (water vapor trap) 18, for example, a cooling type trap device, a column filled with an adsorbent capable of adsorbing water vapor, or any other known equipment or method within the scope of the object of the present invention shall be used. Can be done. When the dehumidifying mechanism (steam trap) 18 is not used, the piping from the reactor 10 to the gas analyzer 14 is required to prevent water vapor in the gas from condensing in the piping. It is preferable to provide a dew condensation prevention mechanism (for example, a ribbon heater) (not shown) for keeping the temperature higher than the temperature of the constant temperature facility.

By such a procedure, it is possible to measure the amount and composition of the gas consumed by the oxidation reaction of coal and the gas generated by the oxidation reaction. As the gas analyzer 14, for example, a general-purpose analyzer such as a gas chromatograph or an infrared spectrophotometer can be used depending on the purpose of measurement. A test of such a process is performed while changing the relative humidity of the humidity control gas introduced into the reactor 10, and the relationship between the water content of coal and its oxidation reaction is analyzed through the component analysis of the gas discharged from coal. Can be verified.

As the coal used in the present invention, all coals such as peat, lignite, lignite, subbituminous coal, bituminous coal, semi-anthracite coal, and smokeless coal, or a mixture thereof can be used. When the method of the present invention is carried out, it is preferable to use it after grasping the characteristics such as the equilibrium water content of the coal used in advance.

Hereinafter, the present invention will be specifically described with reference to Examples. The present invention is not limited to the following contents.

[Example 1]
An oxidation reaction test of coal was actually performed using the oxidation reaction test apparatus shown in FIG. 1.
<Adjustment of water content of coal>
First, the bituminous coal A having the equilibrium water content characteristic as shown in FIG. 2 was used to adjust the water content. About 130 g of bituminous coal A (11) pre-dried to a water content of 2.1% was filled in the reactor 10 (stainless steel, capacity: 1 liter) of this test apparatus. Next, the temperature of the constant temperature facility 15 was adjusted to raise the temperature inside the constant temperature facility 15 to 60 ° C. At that time, a 1-liter stainless steel container was prepared as the humidifier 7, and a saturated aqueous solution in which 600 grams of sodium bromide was previously dissolved in 500 ml of warm water at 60 ° C. as a non-volatile solute was filled in the humidifier. It was installed in 15. After the temperature inside the constant temperature facility 15 became constant, nitrogen was flowed at 135 mL / min as the gas from the gas supply line. The gas temperature in front of the reactor 10 was about 60 ° C, and the relative humidity was about 47% Rh. It became constant. Since the relative humidity of the saturated aqueous solution of sodium bromide at 60 ° C. is expected to be 49.7%, it was confirmed that the humidity control gas having a relative humidity almost as expected could be actually generated.
The relative humidity of the gas after the reactor 10 was about 70% Rh immediately after the start of the test, but decreased with the passage of time, became constant at about 47% Rh after about 6 hours, and then reached a constant value. Retained (see Figure 3). This means that there is no water transfer between coal and gas because there is no change in humidity when passing through coal, and it can be considered that the water content of the bituminous coal A used has become constant. .. After such an operation, the bituminous coal A was taken out from the reactor 10 and its content moisture content was measured by a heat-drying moisture meter. As a result, the moisture content was adjusted to 1.5%.

<Coal oxidation reaction test>
After adjusting the water content of the bituminous coal A, the bituminous coal A was kept filled in the reactor 10 and the temperature in the constant temperature facility 15 was continuously maintained at 60 ° C. After switching the gas from the gas supply line to an oxygen-containing gas (oxygen concentration: about 21%), the gas flow rate is 20 mL / min while bubbling with the humidifier 7, and the oxidation reaction of bituminous coal A is started. did. After the reaction started, _{the concentrations of CO 2} gas and CO gas generated from the reactor 10 were measured by a gas chromatograph 14 [manufactured by Shimadzu Corporation, GC-2014AF (dual packed / FID)] via a cooling steam trap 18. However, this was continued for about 140 hours. The results are shown in FIG.

[Comparative Example 1]
Further, as a comparison, the water content was not adjusted by using bituminous coal A dried to 0%, and further, the saturated aqueous solution was not put into the humidifier 7 to make it a humidity control gas, and other than that. Was subjected to an oxidation reaction in the same manner as in Example 1 above, _{and the concentration of CO 2} gas and CO gas generated from the reactor 10 was measured in the same manner. The results are shown in FIG.

From the results of Example 1 and Comparative Example 1, in the case of Example 1 using coal in a water-containing state, the initial oxidation observed in the case of Comparative Example 1 using sufficiently dried coal. No sharp peak of gas generation was observed. In addition, except for the initial peak, the _{amount of CO 2} gas generated is slightly higher in Example 1 using coal containing water than in Comparative Example 1, whereas in Example 1 for CO gas. It was confirmed that the number of cases decreased.
From this result, it was found that the oxidation reaction according to the water content of coal can be carried out for a long time by using the apparatus and method according to the present invention, and the result that the oxidation reaction of coal differs depending on the water content is actually obtained. I was able to confirm.

1 ... Oxygen-containing gas line, 2 ... Inert gas line, 3 ... Valve, 4 ... Gas supply line, 5 ... Flow control mechanism, 6 ... Dry gas line, 7 ... Humidifier, 9 ... Humidity control gas line, 10 ... Reactor, 11 ... Coal, 12 ... Thermoelectric pair, 13 ... Thermo-hygrometer, 14 ... Gas analyzer, 15 ... Constant temperature equipment, 16 ... Water supply line, 17 ... Drainage line, 18 ... Dehumidifying mechanism (steam trap)

Claims (7)

It is a method of measuring the water content dependence of the oxidation reaction of coal by using an apparatus for evaluating the water content dependence of the oxidation reaction of coal by analyzing the gas consumed or generated by the oxidation reaction. ,
The apparatus includes a gas supply line including an inert gas line for supplying a dry inert gas and an oxygen-containing gas line for supplying a dry oxygen-containing gas.
A dry gas line capable of supplying the dry gas supplied from the gas supply line at an arbitrary flow rate via a flow rate adjusting mechanism, and a dry gas line.
A humidity control gas line capable of supplying the dry gas of the dry gas line as a humidity control gas adjusted to a predetermined relative humidity via a humidifier that humidifies by bubbling in water in which a non-volatile solute is saturated and dissolved .
The reactor is filled with coal and the humidity control gas from the humidity control gas line is introduced.
A gas analyzer for analyzing the gas discharged from this reactor, and
Equipped with constant temperature equipment that can adjust the temperature
At least, the dry gas line, the humidifier, the humidity control gas line and the reactor are housed in the constant temperature facility .
In the method, after adjusting the temperature of the constant temperature facility to a predetermined temperature according to the temperature of the oxidation reaction to be carried out, the method is performed.
i) The process of humidifying the dried inert gas with a humidifier to generate a humidity control gas that has been adjusted to a predetermined relative humidity in advance.
ii) This generated humidity control gas is supplied into a reactor filled with coal, and the relative humidity of the gas supplied to the reactor is the same as the relative humidity of the gas discharged from the reactor. The process of keeping the water content of coal constant until it becomes
iii) Under the state where the water content of coal is kept constant by the step of ii), the oxygen-containing gas conditioned in the reactor is supplied to the reactor by switching the inert gas to the oxygen-containing gas, and the coal is used. And the process of initiating the oxidation reaction of
iv) It has a process of analyzing the gas discharged from the reactor after starting the oxidation reaction of coal.
A method for measuring the water content dependence of the oxidation reaction of coal, which comprises performing the steps i) to iv) while changing the relative humidity of the humidity control gas introduced into the reactor. The first aspect of the present invention is characterized in that the apparatus includes a humidity measuring device capable of independently measuring the relative humidity of the humidity control gas supplied to the reactor and the relative humidity of the gas discharged from the reactor. The method for measuring the water content dependence of the oxidation reaction of coal according to the above. The water content of the oxidation reaction of coal according to claim 1 or 2, wherein the gas supply line of the apparatus includes a switching mechanism capable of switching between the inert gas line and the oxygen-containing gas line. Dependency measurement method . The coal oxidation reaction according to any one of claims 1 to 3, wherein the humidifier of the apparatus includes a mechanism for supplying water in which a non-volatile solute is saturated and dissolved, and a mechanism for discharging water . A method for measuring water content dependence . The invention according to any one of claims 1 to 4, wherein a dehumidifying mechanism for removing water vapor contained in the gas discharged from the reactor is provided between the reactor and the gas analyzer of the apparatus. The method for measuring the water content dependence of the oxidation reaction of coal according to the above. When using a gas analyzer capable of measuring water vapor, the apparatus is characterized by comprising a dew condensation prevention mechanism for keeping the piping between the reactor and the gas analyzer higher than the temperature of the constant temperature equipment. 4. The method for measuring the water content dependence of the oxidation reaction of coal according to any one of 4. The method for measuring the water content dependence of the oxidation reaction of coal according to any one of claims 1 to 6, further comprising a step of removing water vapor contained in the gas discharged from the reactor.

Images