JPS604865B2 - Carbonization method of oil shale - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for carbonizing oil shale, and more specifically, there is a moving grid, fixed wind boxes are provided above and below the moving grid, and a space between the wind box and the moving grid is provided. This invention relates to a method of carbonizing oil shale using a device (hereinafter referred to as a moving grid type device) that is water-sealed and has a structure that prevents the gas inside the wind box from leaking outside.

The carbonization method for oil shale using a moving grating device called a circular grate, straight grate, etc. is widely known as a method for firing and cooling iron ore using such a device, in which iron ore is loaded onto a movable grate. The basic method is to heat or cool the solid particles by flowing a gas almost perpendicularly to the bed of solid particles, which are moved horizontally together with the moving grid.

In this method of carbonizing oil shale using a moving grid type device, as described above, the oil shale to be carbonized is loaded on the moving grid, and the oil shale itself moves in a fixed layer and is subjected to carbonization treatment. It has the characteristic that it does not easily turn into powder during the processing process. As is well known, when oil shale is subjected to carbonization treatment, not only do many cracks occur within the oil shale, but it also becomes brittle and easily fractures with the slightest impact, producing powder. For this reason, for example, crushed oil shale is consolidated from near the top,
When oil shale is carbonized using a device (hereinafter referred to as a mobile device) that forms a moving layer of crushed oil shale in a container that is taken out from near the bottom and circulates a gas through the moving layer, oil When the shale layer moves,
A large amount of oil shale particles are generated due to impact and friction caused by contact between oil shale particles. In this way, when a large amount of oil shale powder is generated, the gas flow resistance within the oil shale layer increases, which not only increases the blowing power but also causes uneven flow of gas within the oil shale layer, resulting in insufficient oil shale formation. Carbonization becomes impossible,
Further, a large amount of oil shale powder is mixed into the carbonized oil, resulting in a decrease in the quality of the carbonized oil. For this reason, an oil shale carbonization method using a moving grid type device that generates very little oil shale powder during the oil shale carbonization treatment process is considered to be an excellent method.

A conventional method for carbonizing oil shale using a moving grid system is described in US Pat. No. 3,325,395;4058905:4
082645, etc., and also in Document 1 [OilShale Data Book (OilShaleDaneB)].
ook): US Department Op Commerce,
National Technical Information Service,
Peabee 80-125636 (U.SDeparemen
to of Commerce, National Te
chnicalInformationService
, PB80-125636)] using a circular-grade carbonization process (Circ's arCraPRebmngP
rocess). Based on the system diagram introduced in this document-1, an overview of the conventional method and its drawbacks will be explained. The system diagram shown in Figure 1 is based on the direct heating type circular-grate carbonization process (Circular Grate Retorti) introduced in Reference-1.
ngProcess), a heating carbonization section W divided by partition walls a and b, a carbon recovery section x divided by partition walls b and c, a first cooling section Y divided by partition walls c and d, and partition walls d and e. The oil shale layer 2 loaded on the moving grid 1 moves through the second cooling section Z divided by , and is exposed to the gas flow supplied to each section to undergo carbonization, carbon recovery, and cooling. That is, in FIG. 1, on the left side of the heating carbonization section W, the moving grid 1 is
Crushed oil shale is loaded on top to form an oil shale layer 2, and as the moving grid 1 moves, the oil shale layer first enters the heating carbonization section W, where the carbonization product gas contained in the circulating gas is absorbed. After being heated and carbonized by being exposed to a hot gas stream obtained by burning, the carbon is transferred to the carbon recovery section x.

The oil shale layer that has moved to carbon recovery zone will be held. Next, the oil shale layer moves to the first cooling section Y, where it is cooled by being exposed to a circulating gas flow, and then moves to the second cooling section Z, where it is cooled by being exposed to an air flow. After the sensible heat is recovered, it is discharged outside the system. The gas that has flowed out of the heating carbonization section W and the carbon recovery section
After being separated, one part is sucked into the blower 3 and taken out as a product gas, and the other part is supplied to the first cooling section Y as a circulating gas.

The gas preheated in the first cooling section Y is supplied to the heating carbonization section W by the blower 4, preheated in the second cooling section Z, mixed with the air supplied by the blower 5, and contained in the circulating gas. A part of the carbonized gas mixed with air and contained in the circulating gas is combusted to produce hot gas, which is then used for heating and carbonizing oil shale. In Figure 1, F represents raw oil shale, D represents waste shale, A represents air, and B represents
is the burner, PC is the compressor and cooler, PG is the product gas, and DOW is the carbonized oil and carbonized water. As mentioned above, the method shown in Figure 1 has the characteristic that air is directly blown into the circulating gas stream to combust a portion of the carbonization product gas, thereby obtaining the hot gas required for carbonization of oil shale without any special equipment. ,
On the other hand, the calorific value of the product gas obtained is extremely low,
There is a drawback that the recovery rate by combustion of the organic carbon remaining after carbonization is low. In particular, the latter poses problems in the following respects. It is well known that the organic carbon contained in oil shale varies greatly depending on the location where oil shale is produced, or even if it is produced in the same region. There were changes like this.

Organic carbon concentration (according to Fischer assay): 4.4-25. $wt% (Based on raw oil shale) After carbonizing these oil shale, the concentration of organic carbon remaining in the shale was measured as follows.

Residual organic carbon concentration: 1.1 to 14.0% by weight (based on raw oil shale) From this, the residual ratio of organic carbon to organic carbon in raw material shale is calculated: 2
It becomes 5-8a weight%.

As described above, it has been found that the proportion of organic carbon remaining in shale after carbonization varies, but is quite large. Therefore, burning this residual organic carbon and recovering the combustion heat is an important factor determining the thermal efficiency of the carbonization process. However, in the conventional carbonization method as mentioned above, the oil shale after carbonization is simply exposed to an air flow and combusted, and usually no other special measures are taken, and a moving grid type device is used. When used, the particle size of shale is large, about 10 to 10 m², so the fuel speed is relatively slow, making it difficult to burn and recover sufficient residual carbon. Therefore, the present inventors have made efforts to eliminate the above-mentioned drawbacks without sacrificing the advantages of the carbonization method using a moving grid type device, and as a result, they have arrived at the present invention. The basic idea is to supply crushed coal to the top of a layer of crushed oil shale after carbonization, and after forming a layer consisting of the oil shale and crushed coal, it is exposed to an oxygen-containing gas flow to remain in the coal and oil shale. This paper proposes a carbonization method using a moving grid device that burns both organic carbon and recovers the heat of combustion.

Specifically, a layer of crushed oil shale loaded on a moving grid passes through a first section where it is heated and carbonized by being exposed to a hot gas flow flowing through the oil shale layer, and then circulates through the oil shale layer. A process for carbonizing oil shale using a moving grid apparatus, the process comprising passing through a second section exposed to an oxygen-containing gas stream, the method comprising feeding coal crushed material on top of the oil shale crushed material passing through the first section. ,
After forming a layer consisting of the oil shale and crushed coal,
By passing through the second section, both the crushed coal and the organic carbon remaining in the oil shale after carbonization are combusted in the second section, and the combustion heat is transferred to the layer consisting of the oil shale and crushed coal. This paper proposes a method for carbonizing oil shale, which is characterized by recovering the increased head heat of the passing gas.

Next, an embodiment of the present invention will be explained based on FIG. 2 in order to clarify the embodiment.

The system diagram shown in Figure 2 is a direct heating method circular grade carbonization process (Circu1arGra and Rapr
This is a case in which the present invention is applied to a heating carbonization section W divided by partition walls a and b, and partition walls b and c.
carbon recovery section X, where coal is supplied from outside,
The oil seal layer 2 loaded on the movable grid 1 moves through the cooling section Y divided by the partition walls c and d, and is exposed to the gas flow supplied to each section to undergo carbonization, carbon recovery, and cooling.

That is, in FIG. 2, on the left side of the heating carbonization section W, crushed oil shale is loaded onto the moving grid 1 using an oil shale supply device (not shown) to form an oil shale layer 2, and the oil shale layer 2 is As the movable grid 1 moves, it first enters the heating carbonization section W, where it is exposed to a hot gas flow obtained by burning the carbonization product gas contained in the circulating gas and subjected to heating carbonization, and then to the carbon recovery section X. Moving.

On the left side of the carbon recovery section
Oil shale layer 2 where S is provided and carbonization has been completed
After forming a layer 6 of crushed coal on top, it is exposed to an air flow to burn both the crushed coal and the organic carbon remaining in the oil shale. In this case, coal is generally easier to burn, so it acts as a ignition source and promotes the combustion of the organic carbon remaining in the oil shale, improving the recovery rate of residual organic carbon in the oil shale after carbonization, as well as burning the coal itself. This can be achieved without adding a new combustion device. Literature-2 [Mathematical Modeling Off Modified in Situ and Above Ground Oil Sheet Retorting;
Modeling of Modified lnS
Ituand AboveKameoundOil Sha
Lawrence Liv
National LaboraP
ryUCRL-53119)], the combustion of organic carbon in oil shale is rate-determined by the diffusion rate of oxygen that diffuses through the ash layer generated by combustion, and in this case, the higher the temperature, the farther away the effective diffusion coefficient is.

Therefore, raising the temperature of the air flow using coal, which is relatively easy to ignite, increases the effective diffusion coefficient of oxygen, which has the effect of improving the combustion recovery rate of residual organic carbon. Coal distills tar when it is heated, so it is desirable to add it to the oil shale after passing through the carbonization zone, but coke is made by distilling the tar, and in this case, it is added to the oil shale after passing through the carbonization zone. It can also be added to oil shale. The gas that has flowed out of the heating carbonization zone W is separated from the carbonization product oil and carbonization product water that flow out together with the gas in a gas-liquid separator S, and is then sucked into the blower 3 and a portion is taken out as a product gas. The other part is first supplied to the heat exchanger as circulating gas.

In the heat exchanger day, the circulating gas is heated by exchanging heat with the hot gas that has flown out of the carbon recovery section X, and is then circulated to the heating carbonization section W again. The gas flowing out of the carbon recovery section is discharged to the outside of the system by the blower 4. A part of the circulating gas is burned in a burner B installed at the gas side inlet of the heating section W to become hot gas and used for carbonization. In addition, air is supplied to the cooling section Y, and after being heated by the sensible heat of the waste shale, a portion of the air is supplied to the carbon recovery section X via line g and a portion is supplied to the heating carbonization section W via line h. , used for combustion of coal and residual carbon, and for combustion of circulating gas, respectively. The remainder is discharged out of the system. On the other hand, the produced oil and water separated by the gas-liquid separator S are separated into oil and water by the oil-water separator E, and then the oil and water are each discharged out of the system.

In Fig. 2, F represents raw material oil shale, D represents waste shale, FC represents coal, A represents air, AH represents hot air discharged outside the system, F represents exhaust gas flowing out of the organic carbon recovery section, and P represents
G indicates product gas, 0 indicates carbonized oil, and W indicates carbonized water. Effectively using the combustion heat of the organic carbon remaining in the coal and oil shale in carbon recovery section X to obtain hot gas for carbonization as in this embodiment example can be said to be an excellent method for improving thermal efficiency. .

Next, the effects of the present invention will be explained using examples.

Example 500 qo of heated air was supplied from line b to the oil shale layer loaded on the lattice at a superficial velocity IN according to the embodiment shown in Fig. 2.
When the temperature of the gas flowing out from the carbon recovery section x was measured, it was 745 qo.

Further, the concentration of organic carbon remaining in the waste shale discharged through the cooling section Y was 2.5% by weight. Comparative Example In the same embodiment as the example, the supply of crushed coal was stopped at the inlet of the carbon recovery section X, and the other conditions were the same as in the example, and the temperature of the gas flowing out of the carbon recovery section
It was 0°C.

Further, the concentration of organic carbon remaining in the waste shale discharged through the cooling section Y was 4.1% by weight. From the examples and comparative examples, it can be seen that by supplying crushed coal to the carbon recovery section, the effect of burning both the coal and the residual organic carbon in the oil shale can be obtained.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a conventional oil shale carbonization method using a moving grid type device, and FIG. 2 is an explanatory diagram showing an embodiment of the present invention. Figure 1 Figure 2

Claims (1)

[Claims] 1. After the layer of crushed oil sier loaded on the moving grid passes through the first section where it is heated and carbonized by being exposed to a hot gas flow flowing through the oil sier layer, it is circulated through the oil sier layer. A process for the carbonization of oil sierre using a moving grid apparatus, the method comprising passing through a second section exposed to an oxygen-containing gas stream, the coal crushed material being fed to the top of the oil sierre crushed material layer passing through the first section. After forming a layer consisting of the oil shale and crushed coal, a second layer is formed.
By passing through the layer, in the second section, both the crushed coal and the organic carbon remaining in the oil sheer after carbonization are combusted, and the combustion heat is transferred to the gas passing through the layer consisting of the oil sheer and crushed coal. A method for carbonizing oil siel, which is characterized in that it is recovered as an increase in sensible heat.