JPH0429715B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for producing dry granular coal fuel with low pyrophoric properties from granular low-grade coal.

As-mined coal often contains undesirably large amounts of water for transportation or use as fuel. This problem is common to all coals, but it is less of a problem for high-grade coals, such as anthracite and bituminous coals, because the moisture content of the coal is usually low and the calorific value of such coals is high. Low-grade coal such as subbituminous coal,
The situation is different for lignite and brown coal. Such coal, in its as-mined condition, generally has a
Contains 65% water by weight. Although many such coals are desirable as fuels due to their relatively low extraction costs and relatively low sulfur content, the use of such low-grade coals as fuels have been largely limited by the fact that they generally contain relatively large proportions of water. Attempts to dry such coal for use as fuel have been hampered by the tendency of such coal to spontaneously ignite and burn after drying during storage, transportation, and otherwise.

The drying required in the case of such low-grade coal is
In addition to removing surface water, it is a deep-reaching drying method that removes the large amounts of interstitial water present in such low-grade coals. On the other hand, when drying high-grade coal, since the content of pore water is relatively small, drying is generally performed for the purpose of drying and removing surface water from the surface of coal particles. It is not intended as a purpose. Therefore, the residence time in the dry zone is usually short and the interior of the coal particles is not heated. This is because such a thing is not necessary for surface drying. Generally, the coal exiting the dryer in such surface water drying processes is at a temperature below about 45°C (110°C). In contrast, the step of removing interstitial water requires a longer residence time, which results in heating deep into the interior of the coal particles. Coal that comes out of the drying process to remove pore water generally has a temperature of about 54 to about 121 degrees Celsius (about 130 to about 250 degrees Celsius).
temperature. When such a process for removing pore water is applied to low-grade coal, the resulting dry coal has significant pyrophoric properties and a tendency to spontaneously ignite, especially at high discharge temperatures, during storage, during transportation, and elsewhere. There is.

Therefore, such low-grade coal is dried,
Efforts have since been made to develop improved methods for safely transporting, storing, and using it as a fuel.

According to the present invention, (a) granular low-grade coal is heated with hot gas in a drying zone to dry it to a moisture content of 20% by weight or less, (b) the obtained dry coal is removed from said drying zone, and ( c) dropping said coal into a fog zone of an inertized effluent; (d) maintaining a fog of inertizing fluid in said fog zone; and (e) inertizing the coal by falling through the fog zone. (f) bringing the coal into intimate contact with the fog so as to cause the coal to absorb a sufficient amount of passivating fluid to produce coal; (f) recovering the passivated coal thus obtained; (g) using as said inerting fluid a virgin vacuum reduced crude oil having a 5% point above 485°C, a characteristic coefficient of at least 10.8 and a flash point of at least 205°C; A method for producing a dry granular coal fuel having a low propensity for spontaneous ignition under normal storage and transportation conditions, characterized in that: a contacting vessel having a granulated coal inlet and a granulated coal outlet positioned such that the granulated coal falls through the vessel to a granulated coal outlet; at least one deactivating fluid mist injector arranged to inject a mist of deactivating fluid into the contact vessel between the inlet and the outlet to bring granulated coal into intimate contact with the deactivating fluid; dry granular low-grade coal selected from subbituminous coal, lignite, lignite and mixtures thereof, characterized in that it is equipped with A close contact device is obtained.

Although cooling dry coal reduces its pyrophoric potential, it may still be pyrophoric. In such cases, the pyrophoric nature of the dry coal can be further reduced by a controlled oxidation process. In such cases, the moisture content of the dried coal can be adjusted to a value somewhat greater than the desired moisture content of the dried oxidized coal product so that some of the drying can be performed in the oxidation zone.

The dry coal product, whether oxidized or not, is further inertized according to the invention by contacting the granular coal with a special inerting fluid to further reduce the pyrophoric properties of the dry coal. can be converted into

Such special deactivated fluids consist of special deactivated oil products that have a combination of the following properties: This special oil consists of a new vacuum crude oil with a minimum characteristic factor of 10.8, a minimum flash point of 205°C (400〓) and a 5% point greater than 485°C (900〓).

The present invention will be explained in more detail below using the accompanying drawings.

In the drawings, each line will be generally referred to as a line without making any distinctions between conduits, conveyors, etc. necessary in the handling of particulate solid materials.

In FIG. 1, a stream of mined coal from line 12 is charged to a coal washing or preparation plant 10 from which the coal stream is withdrawn through line 14. A waste stream consisting of gangue and the like is collected and sent through line 11 for discharge. Although in some cases it may not be necessary to send the mined coal stream to a coal washing or preparation plant prior to application of the method of the invention, in many cases such treatment is desirable. The coal stream recovered from plant 10 is sent through line 14 to a crusher 16 where it is crushed to size and sent through line 18 to hopper 20. Although a size of about 5.1 cm (about 2 inches) or less, or about 0 to 5.1 cm (about 0 to 2 inches) may be suitable, generally about 0 to 2.5 cm (about 0 to 1 inch) or about 0 ~1.9cm
(about 0 to 3/4 inch) is more suitable. The granulated coal in hopper 20 is sent through line 22 to dryer 24. In the dryer 24, the coal passes through the dryer 24 over a grate 26 at a rate determined by the desired residence time within the dryer 24. Hot gas passes upwardly over the moving coal over the grate 26 to dry the coal. In FIG. 1, hot gas is produced by injecting air from line 30 to combust a stream of coal particles introduced from line 34. Combustion of coal particles produces hot gas at a temperature suitable for drying the coal. As will be clear to those skilled in the art, this temperature can be controlled by diluting the air or hot gas with a non-flammable gas, such as exhaust gas from a dryer, by using alternative fuels, by using oxygen-enriched streams, etc. It can be changed by Instead of or in addition to finely crushed coal,
Obviously, alternative fuels, liquid or gaseous, can be used, but in most cases a stream of finely crushed coal is most suitable for use as a fuel for hot gas production. Ash is in dryer 2
4 through line 36. In FIG. 1, the combustion zone 28 is located below the grate 26 to allow the production of hot gases within the dryer 24; however, as can be readily seen, the hot gases may be placed outside the dryer 24 or It can also be generated in other locations. The exhaust gas from the dryer 24 is sent to a cyclone 40 where finely ground solids (generally larger than about 100 tiler mesh) are separated from the exhaust gas and collected through line 44. Exhaust gas, which may remain containing solids smaller than about 100 particles, is passed through line 42 to a fine solids recovery section 46 where it is transported to a finely ground solids collection section 46, where it contains finely ground solids (generally consisting primarily of finely ground coal). ) is line 3
4 and all or a portion of this finely crushed coal is recycled to combustion zone 28. The purified exhaust gas from the fine solids recovery section 46 is sent through a line 48 to a gas purification section 50;
Sulfur compounds, light hydrocarbon compounds, etc. are now removed from the exhaust gas in line 48 if necessary to produce flue gas that can be discharged to the atmosphere. The thus purified gas is discharged through line 51, and the contaminants recovered from the exhaust gas are collected through line 76 and optionally sent to a flare, wet scrubber, or the like. Since the treatment of process gas emissions does not form part of this invention, no further discussion will be given of the cleaning of this gas stream. The fine coal stream recovered through line 34 may in some cases consist of more coal particles than can be used and consumed in combustion zone 28 .
In such cases, the fine coal product is transferred to line 5.
It can be collected through 4. Also, in some cases, the amount of fine coal recovered may be
It is also possible that the hot gas used in the process is not sufficient to reach the required temperature. In such a case, fine coal can be added from line 52.

Dry coal product recovered from dryer 24 is recovered by line 38 and combined with solids recovered from cyclone 40 through line 44 and sent to hopper 116. From here, the dry coal is sent through line 78 to cooler 80. In the cooler 80, dry coal moves through the cooler 80 over a grate 82. Cooling gas is introduced through line 86 into distribution chamber 84 below grate 82 and passes upwardly over the dry coal to cool it. The exhaust gas from the cooler 80 is sent to a cyclone 90 where solids typically larger than about 100 tile mesh are separated and sent to line 9.
4 and the exhaust gas is sent to fine solids recovery section 46 through line 92. Optionally, the gas recovered through line 92 may be sent to combustion zone 28 for use in the hot gas production required in dryer 24. The cooled dry coal is recovered through line 96 and combined with the solids recovered from cyclone 90 to produce a dry coal product. The pyrophoric nature of such dry low-grade coal can be greatly reduced by cooling such coal after drying. In some cases, no further processing may be necessary to produce a dry coal product that does not have excessive pyrophoric properties during transportation or storage.

However, further processing of the dry coal product may be necessary. In such cases, the dry coal product may be coated with a suitable inerting fluid in mixing zone 100. The inerting fluid is introduced through line 102 and thoroughly mixed with the cooled dry coal in mixing zone 100 to produce a coal product that has low pyrophoric properties under normal storage and transportation conditions. The product is recovered from line 104. Although in Figure 1 the dry coal is mixed with the passivating fluid after cooling, the dry coal can also be mixed with the passivating fluid at an elevated temperature before cooling. However, it will usually be preferred to carry out the mixing at a temperature of about 93°C (200°C) or less.

Cooling gas alone can be used in the cooler 80, but it can also be improved by injecting water into the cooler 80. Water can be sprayed onto the dry coal by line 106 and sprayer 108 just before it enters cooler 80, or water can be sprayed onto the dry coal by sprayer 110 immediately after it is introduced into cooler 80. I can do it. Either or both types of devices can be used. In any case, it is highly preferred to ensure that the water is sprayed uniformly over the coal surface. However, an important limitation is that the amount of water added must be as much as is necessary to achieve the necessary cooling of the dry coal by evaporation. Water is sprayed onto the coal in a very fine mist and the amount of water is controlled to such an amount that the added water is substantially completely evaporated from the coal before the cooled coal is removed from line 96. do. In many areas of the United States, relatively dry air is available for use in such cooling operations. For example, in Wyoming, typical summer air conditions are approximately
The dry bulb temperature is 32℃ (90〓) and the wet bulb temperature is about 18℃ (65〓). Such air is very suitable for use in coolers such as those mentioned above. Although virtually any cooling gas can be used, the gas used is typically air. Air is injected in an amount sufficient to fluidize or semi-fluidize the dry coal moving along the grate 82 and in an amount sufficient to prevent water from leaking through the grate 82. Furthermore, this flow must be controlled such that the velocity above the coal on the grate 82 is such that no liquid water is entrained in the discharge stream flowing to the cyclone 90. Preferably, the airflow is at a rate such that the air exiting the cooler has a relative humidity of less than about 85% water. A preferred range is about 50 to about
85% relative humidity. No further elaboration is deemed necessary as such determinations are readily available to those skilled in the art and the flow rate will vary depending on the amount of cooling required.

In yet another variation, water is introduced from the spray device 109 as a fine mist below the grid 82 and
The atomizing device 111 can also be carried by cooling gas into the coal moving along the
It is also possible to spray the coal directly into the coal. Similar considerations can be applied in such cases, and only enough water needs to be added to cause the coal on the grate 82 to achieve the required temperature drop. The use of water as described above reduces the power required by the cooler 80 blower (not shown) and reduces air flow. At first glance, the use of water as described herein may seem undesirable and impractical. This is because the coal has just been dried, and it seems pointless to water it again. Surprisingly, however, the use of the relatively small amount of water required for evaporative cooling does not result in any residual water within the coal; rather, the water is easily removed by evaporation, and the end result is that the cooler 80 It follows that cooling of the coal particles occurs without absorption of any substantial portion of the water added. Although the applicant does not wish to be bound by any particular theory, it is believed that when contact with water is made for a short period of time, the water does not diffuse into the coal and readily evaporates to cool the surface. Seem. Therefore,
The improvement of the present invention, the use of a method of applying water to the dry coal in the cooler 80, significantly reduces the volume of air required and increases the operating efficiency of the cooler 80. Such volume reduction significantly reduces the power required by cooler 80. In some cases,
The power required can be reduced by up to 50% of the power required to dry with air alone. The temperature of the cooling coal can be lowered by the use of evaporative cooling in certain cooling zones where air volume is limited. A typical residence time in the cooler 80 is on the order of 2 minutes, and the water is present for the first minute of residence time in the cooler 80 plus a substantial portion of the time before the dry coal product is removed from line 96. It is highly preferred to allow complete evaporation.

Generally, about 136 to about 363 g (approx.
0.3 to about 0.8 pounds) of water is suitable.

Example: 150 tons/hour of high temperature (93°C (200〓)) dry coal (5% water by weight) was heated to 32°C using direct evaporative cooling.
Cool to (90〓).

Ambient air at 26.5°C (80〓) and 30% relative humidity is available, and water is available at 26.5°C (80〓). This water was sprayed onto the coals and air was forced upwardly through the coals. Air is 272,000Kg/hour (600,000
The water was sprayed onto the dry coal at a rate of 3639 kg/hour (8023 lb/hour). The effluent stream produced was at 32°C (90°C) and the relative humidity was 68%. Coal temperature is 32℃ (90
〓). A suitable residence time is 2 minutes. When using a slotted grate conveyor, a pressure drop of 12 inches of water across the grate is considered adequate. With this pressure drop, the flow rate through the slot is preferably about 300 feet/second to achieve the required pressure drop and prevent water from passing through the slot. In this example, the required slot area is 0.81 m ² (8.7 ft ² ). The bed depth was 1.2 m (4 ft) and the bed was assumed to have undergone 50% expansion or fluidization.

The cross-sectional area in the discharge zone in the cooler 80 above the cooler grate may need to be larger than the grate 82 to prevent entrainment of water into the exhaust gas.

In operation of the dryer 24, the dry coal discharge temperature is generally about 54 to about 121°C (about 130 to about 250°C), preferably about 88 to about 104°C (about 190 to about 220°C).
〓). The hot gas is passed upwardly through the coal over the grate 26 at a rate suitable to maintain the coal in a fluidized or semi-fluidized state above the grate 26. The residence time is selected to achieve the required dryness, but it is easy for one skilled in the art to determine the residence time empirically based on the particular type of coal used, etc. For example, when drying subbituminous coal,
Initial moisture contents of about 30% by weight are common. Preferably, such coal is dried to a moisture content of about 15% by weight or less, more preferably from about 5 to about 10% by weight. Lignite often contains water on the order of about 40% by weight and is preferably dried to a water content of less than about 20% by weight, and more preferably from about 5 to about 20% by weight. Lignite can contain about 65% water by weight, and in some cases more. In many cases,
Such lignite must be treated with other physical separation steps to remove some of its moisture before drying. In any case, these coals contain approximately 30% by weight
It is desirable to dry to a moisture content of preferably about 5 to about 20% by weight. Determination of the residence time of such coal in the dryer 24 can be readily determined experimentally by those skilled in the art for each particular coal. Determining the appropriate residence time depends on many variables, which will not be discussed in detail here.

The moisture content stated herein is based on the 1978 ASTM
Standards Yearbook, Part 26, ASTM D3173-73 “Standard Test Method for Moisture in Analytical Samples of Coal and Coke”
It was determined using

The temperature at which the dry coal is taken out from the dryer 24 is
It can be easily controlled by varying the amount of fine coal and air introduced into the dryer 24 so that the hot gas mixture produced after combustion is at the required temperature. The temperature directly below the grate 26 must be controlled so that the coal on the grate 26 does not spontaneously ignite. Suitable temperatures for most coals are about 104 to about 570°C (about 250 to about 950°C).

In the operation of the cooler 80 as described above, the first
The temperature of the dry coal charged to the cooler 80 in the illustrated process is generally the temperature of the dry coal removed from the dryer 24 which has not experienced significant process heat loss. The temperature of the dry coal is approximately
Below 38℃ (100〓), preferably about 27℃ (80〓)
It is desirable to cool it to the following temperature. The cooling gas is passed upwardly through the coal on the grate 82 at a rate suitable to maintain the coal in a fluidized or semi-fluidized state on the grate 82. Residence time, amount of cooling air, amount of cooling water, etc. can be easily determined experimentally by those skilled in the art. Such decisions will depend on the amount of cooling needed, etc. As is well known to those skilled in the art, after drying, low grade coal is highly susceptible to spontaneous ignition and combustion during storage, transportation, and the like. However, it would be desirable for such coal to become more widely available than is currently possible. These coals have a high water content, at least to a large extent, requiring large freight charges due to the extra water, and likewise because a significant portion of the coal is water rather than combustible carbonaceous material. The calorific value of coal decreases. Due to their low calorific value, the uses of these coals are limited. This is because many furnaces are not suitable for burning such low calorific value coal. On the other hand, when the water content is reduced, the calorific value increases. This is because, in this case, a large portion of the coal is composed of combustible carbonaceous material. It is therefore highly desirable to dry such coal prior to transport.

Often such dry coal is heated to around 38℃
(100°) or less, preferably about 27° C. (80°) or less, is sufficient to prevent spontaneous ignition of the dry coal. All dry low-grade coal
Although not so inert that it can be stored and transported without further treatment after cooling, such dry low-grade coal is often sufficiently inert to avoid spontaneous combustion. becomes inert after cooling. Our findings here indicate that spontaneous ignition of such low-grade coals can be reduced by further reducing the spontaneous ignition potential of dry coal using suitable inerting fluids, as detailed below. , can be further suppressed. The inerting fluid is preferably applied by intimate mixing with the dry coal to produce a dry coal product with a low propensity for spontaneous combustion. The use of inerting fluids also reduces the tendency of dry coal to dust.

Another method of reducing the pyrophoric nature of dried coal is to use a controlled oxidation step after the drying operation and before cooling of the dried coal. Such a modification is shown in FIG. In this case, dry coal is passed through line 38 to coal oxidizer vessel 60.
sent to. Dry coal is charged to oxidizer 60 and passes downwardly through the oxidizer 60 from upper end 62 to lower end 64 at a controlled rate to obtain the required residence time. The flow of dry coal downward through oxidizer 60 is controlled by grate 66 . Grate 66 supports the coal within oxidizer 60 and also controls the amount of dry oxidized coal removed from line 78. A free oxygen-containing gas, such as air,
It is introduced into oxidizer 60 through line 68 and air distribution device 70 . The air distribution device 70 is the third
This is shown in more detail in the figure. Air distribution system 70 has a plurality of lines 122 with suitable openings (not shown) disposed along the length of the lines for exhausting air into oxidizer 60.
have. In addition, the line 122 is the protective component 1
It is located below 20. Protective component 120 prevents clogging of the air outlet openings of line 122 and prevents line 122 from being damaged by falling coal. Spacing 124 between protective parts 120
is to allow coal to pass between the protective parts 120, and the spacing 124 is generally at least three times as large as the largest coal particle diameter. Oxidizer 6
0 is also equipped with a coal distribution device 112 to evenly distribute particulate solids. Coal distribution devices can be of various constructions well known to those skilled in the art. Exhaust gas is recovered from oxidizer 60 by line 72 and sent to gas cleaning section 50 for processing prior to removal, as shown in FIG.
The grid 66 can have a variety of configurations well known to those skilled in the art, and supports and controls the amount of particulate solids flow moving downwardly through the reaction zone to control the amount of particulate solids passing through the reaction zone. The structure is such that it causes uniform downward movement of solids.

The grate shown in FIG. 3 consists of a restraining plate 121 and a push rod 123 that extend across the bottom of the oxidizer 60 to support the dry coal within the oxidizer 60 while removing the required amount of dry oxidized coal. It's getting old. A deflection plate is shown as a protective component 120 for an air intake line 122. A star feed device or the like 125 is provided in line 78 to prevent air flow in line 78 when the dry oxidized coal is removed. lattice 66
In operation, coal is pushed and removed from the restraint plate 121 by the movement of the push rod 123 which is reciprocated to push and remove the required amount of coal from the restraint plate 121. Although air can be introduced from higher up in the oxidizer 60 or from multiple locations, it is preferred that substantially all of the air be introduced near the bottom of the oxidizer 60.

A problem that exists with the oxidation of dry coal in oxidizer 60 is that the coal tends to become increasingly hot as it is oxidized. High temperatures are not required for coal inertization and are undesirable because they increase the load on the cooler and increase coal product consumption in the oxidizer 60. About 6 to about 25 pounds of oxygen per ton of dry coal can be used, but preferably about 6 to about 15 pounds of oxygen is used per ton of dry coal. . Using such amounts of oxygen generates significant amounts of heat. In order to maintain a stable temperature within oxidizer 60, it is desirable to limit drying in dryer 24 to just below that required for the final dry coal product. In other words, dryer 24 provides less drying than is necessary for the dry oxidized coal product. In many cases, when performing the oxidation of a dry coal stream, it is desirable to leave about 1 to about 5% more water by weight (based on the weight of the coal) in the dry coal stream than the desired water content in the final dry oxidation product. desirable. The presence of excess water causes cooling of the dry coal by evaporation of water during oxidation. The amount of water left when an oxidation step is used is preferably that amount necessary to remove by evaporation the heat generated by the necessary oxidation. In most cases, about 2.7 to about 6.8 kg per ton of coal (about 6 to about
When using 15 lbs.

A suitable coal temperature as it exits the oxidizer 60 is about 80 to about 107°C (about 175 to about 225°C).
Desirably, the net increase in coal temperature in oxidizer 60 is small. Although high temperatures may occur locally in the oxidizer 60, the coal extraction temperature is approximately
The temperature is preferably 80 to about 107°C (about 175 to about 225°C). Although the coal charging temperature may vary, it is likely that in most cases the dry coal will be charged to the oxidizer at a temperature close to the discharge temperature.

Regarding the amount of water removed by evaporation in the oxidizer vessel, it should be noted that the desired drying amount in this case is significantly less than the drying amount required to produce a dry low-grade coal product. It is. Therefore, this controlled oxidation step is not suitable for use as the main drying step and is more suitable for use after the coal drying step. In that case, the reactivity of the dry coal is suitable for inactivation by a controlled oxidation step, and a large proportion of water will be removed.

Thorough mixing of dry coal and the special inerting fluid according to the invention can be easily carried out in a container such as that shown in FIG. In FIG. 4, dry coal product or oxidized dry coal is charged to contact vessel 140 from line 46. The contacted coal is withdrawn from line or discharge passage 148. In the contacting vessel 140, the special inerting fluid is sprayed into the vessel 140 from a misting device 150 (which is a spray nozzle 152, as shown in FIG. 4). kept in a fine mist by Obviously container 14
0 can be of various configurations and any reasonable number of nozzles 152 can be used. However, the upper end 142 and lower end 1 of the contact container 140
44 must be sufficient to bring the coal into intimate contact with the special inerting fluid as it passes through vessel 140.
Inerting fluid is sprayed from line 158 through nozzle 152 into container 140 . Deflection device 1
43 may be optionally installed to separate the flow of coal to facilitate contact with the inert fluid.

Another embodiment of a suitable contact vessel is shown in FIG. The contact container shown in FIG.
2 and has a plurality of protrusions 154 on the inner wall of the container. The protrusions are adapted to impede the steady fall of the granular coal solids within the container 140, thereby promoting intimate contact between the granular solids and the special inerting fluid mist present within the container 140. In operation, protrusion 154 can be of virtually any effective shape and size. The misting device 150 shown in FIG. 5 consists of a tube 156 located below the projection 154. Tube 156 has a plurality of spray nozzles 152 . Spray nozzle 152
can also be placed on the wall of the container 140. Additionally, a deflection device 160 is mounted near the lower end 144 of the vessel 140 so that the granular coal solids stream is directed toward the vessel 140.
The solids stream is adapted to be deflected as it is discharged from zero. Tube 15 containing spray nozzle 152
6 is located below the deflection device 160.

When operating the container shown in Figures 4 and 5,
The granular coal stream is introduced into the top of the vessel 140 and falls through the vessel 140 by gravity into continuous contact with a fine mist of special inerting fluid. The residence time depends on the magnitude of the flow through the vessel 140, the vessel 14
It can vary greatly depending on whether or not there is a protrusion within the 0. The contact time and amount of mist are adjusted to obtain the required amount of special inerting fluid that is thoroughly mixed with the coal. Preferably the coal is about 20
Charge the fog zone at a temperature of ~45℃ (approximately 70℃ to approximately 110℃).

The special deactivating fluid used in this invention is 485
It is a new vacuum crude oil with a 5% point greater than 900 °C (900 °C), a characteristic factor of 10.8 or higher, and a minimum flash point of 205 °C (400 °C).

The meaning of the term flashpoint is well known, so I will not explain it. This particular inert oil composition is 5%
It is important that the point is obtained by fresh crude oil distilled under vacuum under conditions greater than 485°C (900°C). Fresh crude oil is an oil or oil fraction that has not been subjected to any special heat treatment to produce a distributed distillate as it is removed from the oil reservoir.

This special oil composition has a 5% point of 485°C (900°C).
It is obtained by vacuum distillation of crude oil under conditions greater than 〓). This condition is ASTM-
D1160-77 “Standard Method for the Distillation of Petroleum Products Under Reduced Pressure” (ASTM Standards 1978 Yearbook, No. 23)
It was determined using the test values obtained for new crude oil by the method described in Section 1). As an example, crude oil was vacuum distilled at various cut points ranging from 316°C to about 538°C (600-1000°C) before being contacted with dry coal. Oxidation rate constants were measured before and after contact with distilled oil. Generally 316℃ (600
〓), the degree of inactivation is inappropriate, and 427℃
(800〓), the degree of inactivation was barely effective at best;
〓) The distilled oil was sufficiently satisfactory.

Characteristic coefficients are unique physical properties of hydrocarbons defined by the following equation:

K=Tb ^1/3 /G where K=characteristic coefficient Tb=average boiling point °R G=16℃/16℃ (specific gravity of 60〓/60〓 °R=〓+460 The average boiling point is calculated from the paper by RL Smith and KMWatson. "Boiling points and important properties of hydrocarbon mixtures"
(Industrial and Engineering Chemistry,
Vol. 29, pp 1408-1414, December 1937), the above ASTM-D1160-77
or 10, 30, 50, 70 and 90 percent points measured by the method of ASTM D86 “Standard Methods for Distillation of Petroleum Products” (ASTM Standards 1978 Yearbook Part 23).
The score was decided using. ASTM D86 is concerned with products that decompose when distilled at atmospheric pressure.

A difference of (2-3)/10 in the characteristic coefficient can be considered small, but it is easy to determine this coefficient with an accuracy of 0.1, and one can use this coefficient with considerable confidence and reliability. and can be interpreted. This coefficient is useful for identifying hydrocarbons. For example, a material with a characteristic coefficient of 9.5 is
It is a pure polynuclear aromatic hydrocarbon called PNS, which is highly carcinogenic. At the other end of the scale, substances with a characteristic factor of 13 are pure paraffins, such as harmless petrolatum. The characteristic coefficients are well correlated with many other physical properties of the oil, such as molecular weight, viscosity, thermal expansion, specific heat, critical properties, heat of combustion, and others.

This special oil composition can be used in any suitable amount, but typically 1.9 to 15 (0.5 to 4.0 gallons) of special oil per 907 kg (2000 lbs) of dry coal.
is appropriate. Higher amounts of special oil can be used if necessary for dust control.

Although it may be desirable to use an oxidation step in carrying out the method as shown in Figures 1 and 2,
Depending on the coal feedstock, such a step may not be necessary. In general, cooling of all low-grade coals is believed to be necessary in order to produce the desired dry coal fuel that is not undesirably prone to spontaneous combustion. The method chosen depends largely on the particular coal feedstock used. Another variable that influences the choice of method for certain low-grade coals is the risk associated with spontaneous ignition. For example, excessive treatment is desirable for dry coal products to be transported by ship or otherwise, as the risk of damage from spontaneous ignition is much greater than for coal that is stacked near coal consuming facilities. Although the method chosen will depend on various considerations, the particular process combinations described above are suitable for processing virtually all low-grade coal to produce dry fuel products with low pyrophoric properties. seems to be effective.

Although the present invention has been described above with reference to some preferred embodiments, the embodiments described herein are not intended to limit the present invention, but are merely for illustrative purposes. Many variations and modifications are possible without departing from the scope of . Many such variations and modifications will become apparent and may be desirable in light of the foregoing description of the preferred embodiment.

[Brief explanation of drawings]

The accompanying drawings illustrate an embodiment of the invention, in which Figure 1 is a schematic diagram of the drying stage of the process of the invention, and Figure 2 is a schematic diagram of another drying embodiment of the process of the invention. , FIG. 3 is a schematic diagram of an oxidizer vessel suitable for use in practicing the method of the invention, and FIG. Figure 5 is a schematic diagram of another apparatus suitable for use in bringing about contact between granular coal and an inerting fluid; be. In the figure, 24...Dryer, 26...Grate (first support device), 80...Cooler, 82...Grate (second support device), 84...Cooling gas distribution chamber, 10
0... Mixing zone of coal and inert fluid, 108,
109,110,111...Water spray device, 60...
...Coal oxidizer container, 62...Top end of 60, 64
... lower end of 60, 30 ... air inlet device (line), 44 ... air outlet device (line), 34 ...
...Granular coal inlet (line), 66...Grate, 70
... Air distribution device, 78 ... Coal recovery line, 1
22...Line having an air ejection opening, 120...
...Protective parts (deflection plate), 124...120 intervals,
112...Coal distribution device, 140...Contact vessel,
142...The upper end (first end) of 140, 144...
...lower end (second end) of 140, 146...140
148... 140 outlet (line), 150... mist spray device, 152... spray nozzle, 154... protrusion, 156... tube (tubular part), 160... deflection device. .

Claims (1)

[Claims] 1 (1) (a) Granular low-grade coal is heated in a drying zone with high-temperature gas to dry it to a moisture content of 20% by weight or less, and (b) the obtained dry coal is transferred to the drying zone. (c) charging and dropping said coal into a fog zone of an inertizing fluid; (d) maintaining a fog of inertizing fluid in said fog zone; and (e) by dropping said coal through a fog zone. (f) bringing the coal into intimate contact with the mist so as to cause the coal to absorb a sufficient amount of deactivating fluid to produce deactivated coal; (f) deactivating the coal so obtained; (g) using fresh vacuum crude oil having a 5% point above 485°C, a characteristic coefficient of at least 10.8 and a flash point of at least 205°C as said inerting fluid; A method of producing a dry granular coal fuel that has a low tendency to self-ignite under storage and transportation conditions. 2. The method according to claim 1, wherein the coal is charged into the fog zone at a temperature of 20 to 45C. 3. Claim 1, wherein the coal is selected from subbituminous coal, lignite, lignite, and mixtures thereof.
The method described in. 4. The coal is heated to 54 to 121 in the coal dry zone.
2. A method according to claim 1, wherein the method is heated to a temperature of .degree. 5 Add 1.9~15 (0.5~
4. The method of claim 1, wherein 4 gallons of the fresh vacuum crude oil are atomized. 6. The method of claim 1, wherein the removed dry coal is cooled to a temperature below 38°C before being sprayed with the fresh vacuum crude oil. 7. The method of claim 1, wherein the coal is dried to a moisture content of 5 to 20% by weight. 8 (a) a granulated coal inlet and a granulated coal outlet so located that the dry granulated coal charged into the vessel through which the granulated coal inlet falls through the vessel to the granulated coal outlet; (b) connecting said inlet and said outlet in said contacting vessel to bring said granulated coal into intimate contact with said inerting fluid as said granulated coal falls through a mist of said inerting fluid; and at least one inerting fluid mist injector arranged to inject a mist of said inerting fluid between subbituminous coals, lignites, brown coals and mixtures thereof. A device for bringing dry granular low-grade coal, selected from among others, into intimate contact with an inertizing fluid to reduce its pyrophoric properties. 9. Apparatus according to claim 8, wherein the container has projections located on the inner wall of the container to promote intimate contact between the granulated coal and the mist. 10. The device of claim 8, wherein the mist spray device comprises at least one tubular part having a plurality of spray nozzles arranged on the inner wall of the container. 11. The device of claim 8, wherein the tubular part is located beneath at least one of the projections. 12. The apparatus of claim 8, wherein at least one deflection device is located near the granulated coal outlet for deflecting the granulated coal. 13. The device of claim 8, wherein the mist spray device further comprises at least one tubular part with a plurality of spray nozzles arranged below the deflection device.