JPS5945709B2 - Oil shale carbonization method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for efficiently and economically carbonizing oil shale and recovering shale oil using a plurality of shaft furnaces.

As a method for carbonizing oil shale using a shaft furnace, US Pat. No. 4,116,810 (1978) and US Pat.
No. 479, No. 4092237, etc., and the former two methods are carbon distillation methods in which oil shale and process gas are brought into contact with each other by a countercurrent in a single shaft furnace.

The disadvantage of these methods is that a large amount of carbon remains in the carbonized sier (hereinafter referred to as sventsier) and cannot be recovered and used.

It is thought that the latter was invented to improve this drawback.

The latter, US Pat. No. 4,092,237, connects two shaft furnaces in series, with preheating carbonization in the front furnace and carbon recovery (
(hereinafter referred to as "C recovery") and cooling.

The drawback of this method is that oil shale at a high temperature of 500 to 700°C is once discharged from the front furnace outside the furnace and then charged again to the after furnace while still at high temperature, so it cannot be used in actual plants without any trouble. is extremely difficult, if not impossible.

In addition, in countercurrent shaft furnaces, oil shale is violently powdered during descent into the furnace, causing dust generation.

Carbonization of oil shale consists of four steps: preheating, carbonization, carbon recovery, and cooling, and preheating is achieved in a relatively short time, but the basic process for carbonization, carbon recovery, and cooling is heat transfer through packed beds. Yes, the time required is similar.

On the other hand, in the field of direct reduction of iron ore, there is a technology that uses four retort furnaces to perform the reduction (Japanese Patent Publication No. 43-1706).
(See Publication No. 6).

The present invention was inspired by this technology, and aims to provide a method for carbonizing oil shale that can be efficiently carbonized under high pressure and with less pulverization.

In the present invention, each of the four shaft furnaces is used for the four processes of carbonization, C recovery, cooling, and charging and discharging, and the charging and discharging process functions as a moving bed, and the other three processes function as a fixed bed, allowing batch continuous operation. Carbonization is carried out, which allows air to be used for C recovery, and also eliminates the problem of powdering of oil shale in the furnace, which is a defect in the moving bed.

Figure 1 shows the carbonization system of the present invention, and Figures 2 and 3 show the carbonization system of the present invention.
The figure shows the operating method.

Figure 4 shows the structure of the carbonization furnace that constitutes this carbonization system.

FIG. 5 shows another example of a carbonization furnace, and FIG. 6 shows a recovery device for shale oil, which is an important part of the carbonization furnace.

Furthermore, FIG. 7 shows a cleaning device for preventing coking of the recovery device.

FIG. 8 shows another actual embodiment of the carbonization system of the present invention.

FIG. 1 shows an example of the carbonization method of the present invention.

There are four shaft furnaces 1a, 1b, 1c, and 1d each containing a built-in oil shale extraction device.

The four basic processes of carbonization, ``charging and discharging,''``carbonization,'' ``C recovery,'' and ``cooling,'' are divided into four shaft furnaces, each with one step each, allowing all four units to perform the entire carbonization process. It is becoming established.

Therefore, if the switching time of the shaft furnace is chosen to be 1 hour, for example,
Regarding 1a, within one hour, the oil shale was charged and discharged, then the "carbonization" process started, and one hour later, the "C recovery" process was started, and then the gas conditions were changed to "cooling". Complete one cycle in 4 hours.

This situation can be better understood by looking at the explanatory diagram of the four-furnace operation method shown in Figure 2.

In FIG. 1, the shaft furnace 1a is cut off from the process gas system for carrying out carbonization, and the connecting valve 17a to the flare stack 9 is opened simply to maintain the inside of the furnace at normal pressure.

The furnace is initially loaded with carbonized spent steel and is further maintained at high pressure with oxygen-free cooling gas.

First, the valve 17a is opened to release the gas inside the furnace and reduce the pressure inside the furnace to normal pressure.

After that, the spent siere is cut out using a cutting device built into the furnace.

At this time, new oil shale is simultaneously charged from the charging device at the top of the furnace, so that the inside of the furnace is completely replaced with new oil shale.

Next, the valve 12a is opened to replace the air in the furnace with cooling gas.

After the air replacement is completed, the valve 17a is closed and the inside of the furnace is pressurized to a predetermined pressure.

With the above steps, charging and discharging are completed and the state is ready for switching to the next step.

It is also possible to use the cooling gas from the valve 12a to wash away the fine powder contained in the newly introduced oil-bearing mineral and release it outside the system, after which the valve 12a is closed and the carbonization operation can proceed.

In FIG. 1, the shaft furnace 1b closes the maf valve 12b and opens the valve 15b.

Then, the valve 11b is opened to introduce high temperature carbonization gas into the furnace.

The gas generated by heating the oil shale and evaporating the oil in the furnace is discharged from the valve 15b, cooled by the oil separator 2, and the oil contained in the gas is separated.

Thereafter, the pressure is increased by the circulating compressor 4, and it enters the heat exchanger 5, where it is primarily heated, and further heated in the heater 6 to a temperature necessary for carbonization, for example, about 800°C.

On the other hand, the gas after exiting the circulation compressor 4 is branched and supplied to the outside of the line through the pressure control valve 18 as surplus fuel gas, and at the same time passes through the flow rate control valve 3 to the shaft furnace 1d which is in the cooling process.
The gas itself is heated and becomes a high-temperature gas that merges with the carbonized gas mentioned above.

In this case, if the temperature is insufficient, the bypass valve 10 is opened and a portion of the temperature is supplied to the heater 6 and heated.

The thus regenerated carbonization gas is supplied to the furnace 1b from the valve 11b, and the carbonization of the oil shale in the furnace proceeds.

After confirming that the valve 11a is opened when the carbonization is completed, the valve 15b is closed, and then the valve 11b is closed.

In this way, the carbonization process is completely completed and a state is entered for proceeding to the next step.

In FIG. 1, the shaft furnace 1C first opens the valve 20 and then closes the valve 19 to convert the C recovery gas system to inert gas.

Thereafter, the valve 13c is opened and then the valve 16c is opened to replace the shaft furnace 1c with inert gas.

Then, open the valve 19 and close the valve 20 to supply air to the shaft furnace 1.
The carbon in the high-temperature spent steel is burned and recovered as heat.

The high temperature air is discharged from the valve 16c and supplied to the heat exchanger 5, where it is used to heat the cold carbonized gas mentioned above.

When the temperature further decreases, the oil contained in the gas is separated by an oil separator 8 and then released into the atmosphere.

When C recovery is completed, valves 13c and 16c are closed after confirming that valve 13b is open.

The valve 20 can be appropriately sized to adjust the oxygen concentration.

In FIG. 1, the shaft furnace 1d first opens the valve 14d, and then opens the valve 12d to introduce cooling gas into the furnace.

The furnace is filled with high-temperature spent gas from which C recovery has been completed, and this is cooled down, and the cooling gas side is preheated and exits from the valve 14d to be reused as carbonized gas.

After cooling is completed, after confirming that the valve 12c is open, close the valve 12d and then close the valve 14d.

Through the operations described above, oil shale is carbonized in a stationary state and pulverization is prevented.

Further, there is an effect that C recovery is carried out safely and efficiently.

In this persimmon example, an indirect heating method was used to heat the carbonized gas.

Therefore, the excess gas leaving the valve 18 is a high-calorie gas.

However, even if it is illegal, it is also possible to carry out direct heating as shown in US Pat. No. 3,325,395, in which air is blown into carbonized gas and heated by combustion.

However, in this case, the surplus gas will be low calorie gas.

Normally, when oil shale is carbonized, a considerable amount of carbon remains in the spent shale, and the recovery and use of this carbon increases the thermoeconomic efficiency of the entire carbonization plant.

Therefore, a four-furnace operation as shown in FIG. 2 is common.

However, if the residual carbon is relatively small, the C recovery step may be omitted.

In this case, three-furnace operation as shown in FIG. 3 is possible.

Next, the structure, operation, and effects of the carbonization furnace of the present invention will be explained.

FIG. 4 shows a rectangular cross-section furnace incorporating a reciprocating cutting device.

This furnace is used when carrying out the drying method shown in FIG.

Oil shale is carried to the top of the furnace by a charging conveyor 5 and charged into a charging hopper 2 via a top hopper 3 .

The furnace top valve 4 is provided at the outlet of the furnace top hopper 3 to shut off the gas inside the furnace from dissipating outside the furnace.

However, when the furnace is in the "charging and discharging" period, this valve is opened and oil shale is continuously charged into the furnace.

1 has a structure that isolates the inside of the furnace from the outside air with a furnace shell and keeps the inside of the furnace airtight.

An inlet 1-2 for a process gas such as carbonization gas or cooling gas is provided at the top of the furnace shell 1, and a gas outlet 1-2 is provided at the bottom.
-3 is placed.

The oil shale charged into the furnace is supported on the furnace bottom plate 10, and if the cutting rod 8 is stopped, the oil shale is supported on the furnace bottom plate 10.
Stably stored on top.

The cutting rod 8 is reciprocated by a driving cylinder 9-2 via a connecting rod 9-3 and a head 9-1 to cut out the oil shale on the furnace bottom plate.

Note that 9-4 is the sole structure of the furnace shell penetrating portion of the connecting rod 9-2.

Twenty outlets are provided at the lower end of the furnace shell.

A seal valve 7 is attached to each.

The spent siere cut out from inside the furnace is discharged through the discharge chute 6.
and is carried away by the discharge conveyor 14.

At the bottom of the furnace bottom plate 10 is a Scheer oil recovery device 11, the detailed structure of which is shown in FIG.

The structure of the hearth bottom plate 10 is a lattice structure as shown in the cross section AAA, and the spent sear oil does not pass therethrough, but the condensed sear oil passes through the lattice and flows on the hearth bottom plate oil collection part 10-1. The oil is stored in the oil recovery device 11.

Furthermore, if the valve 12-1 is opened, this oil will be discharged from the discharge pipe 1.
2 and is forcibly discharged by the furnace pressure and enters the Schier oil reservoir 13.

In the lower part of the carbonization furnace, oil separated from the oil shale evaporates from the beginning to the middle of the carbonization period, condenses in contact with the cold oil shale in the lower part of the furnace, and is recovered outside the furnace by the above-mentioned recovery device.

However, in the latter half of the carbonization period, the temperature in the lower part of the furnace gradually rises, and oil is not recovered. Rather, the oil remaining in the furnace bottom plate 10 and the oil collection section 10-1 is reevaporated or carbonized. There is sex.

There is no problem with re-evaporation because an oil separation device is installed downstream and the oil is recovered there, but the carbonized portion gradually grows and eventually becomes a hindrance to oil recovery, so carbonization is recommended because the lower part of the furnace is at a high temperature. In the latter half of the period or when entering the C recovery period, residual oil is washed away as shown in Figure 7 to prevent carbonization and to withstand long-term operation.

To wash the residual oil, open the valve 16 to introduce superheated steam, and by means of the valve 18 superheated steam is introduced from the injection pipe 19 installed on the furnace bottom plate oil collecting section 10-1 and the nozzle 19-1 installed therein as shown in cross section BB. The oil is injected to blow off the remaining oil and discharged from the furnace through the Schier oil recovery device 11.

Inert gas is used instead of superheated steam to clean residual oil.
It is possible to use water, soft oil, etc. depending on the amount of oil remaining.

The characteristics of the carbonization furnace shown in Figure 4 are as follows: First, new oil shale is continuously charged at the same time as spent shale is cut out during the charging and discharging stage. Since the material is charged quietly and smoothly without any shock, there is no risk of pulverization due to falling, which is the case when charging into an empty furnace, as seen in general batch furnaces. do not have.

Furthermore, since a reciprocating cutting frame is used, the spent shale in the furnace flows down in a so-called perfect plug flow.

This allows you to know exactly where the boundary between old and new Sierre is, if you have measured the amount charged or discharged.

Therefore, the boundary between old and new Sierre can be freely set at any position.

Since the exchange of oil shale is completed during the charging and discharging period, all heat treatment is completed while the shale in the furnace remains stationary and does not move after the carbonization period.

Therefore, it is a completely new carbonization furnace that functions as a fixed bed reactor and as a moving bed in terms of charging and discharging.

In a general moving bed shaft furnace, raw materials are charged and discharged while maintaining airtightness inside the furnace, so the seal valve used at the top or discharge part of the furnace is a stop valve that shuts off the raw material and gas. A seal valve and two other valves are used in combination, but in this carbonization furnace, the pressure inside the furnace is reduced to normal pressure during the charging and discharging stage.

Seales can be exchanged with all seal valves open.

Therefore, no stop valve is used in the furnace top seal valve 4 and the discharge valve 7, which simplifies the process.

Further, in order to protect the furnace top seal valve 4 from high-temperature gas, the charging pipe 2-1 is always loaded with siel to shut off high-temperature gas.

Regarding the discharge valve, the discharge valve is closed after the charging and discharge period is completed, and then the cutting frame is moved a little so that a small amount of ciel is stored on the discharge valve as shown in Fig. 4, and the high temperature gas is removed from the discharge valve 7. protect

FIG. 5 shows a circular section furnace incorporating a rotary cutting device as another embodiment of the carbonization furnace of the present invention.

This furnace is similar in structure and operation to the carbonization furnace shown in FIG. 4, except that the furnace is a circular cross-section furnace and the cutting device is of a rotary plate type.

Therefore, only the cutting device will be described.

8 is a cutting device, and as shown in the right figure, a cow horn-shaped impeller is attached to the upper surface of a thin disk. When this is rotated by a driving device 9, the sierre is smoothly cut out by the action of this impeller.

Moreover, if the diameter of the impeller is selected correctly in relation to the inner diameter of the furnace, the flow of the siel in the furnace becomes almost a complete plug flow, similar to the reciprocating cutting frame shown in FIG. 4, and old and new siel can be freely replaced.

Other practical aspects of the carbonization method of the present invention are as follows.

(1) In the carbonization system shown in Figure 1, oxygen-containing gas (a mixture of air and inert gas) during the C recovery period is blown into the top of the carbonization furnace, discharged as high-temperature gas from the bottom of the furnace, and then passed through the heat exchanger. 5 and an oil separator 8.

However, some oil shale species have a large amount of residual carbon after carbonization, and the exhaust gas tends to reach abnormally high temperatures in some cases.

Therefore, in such a case, it is better to adopt a method in which the oxygen-containing gas is blown from the lower part of the carbonization furnace and discharged from the top of the furnace.

This has the effect of preventing overheating of the cutting device and oil recovery device built in the lower part of the furnace.

(See Figure 8). (2) In FIG. 1, the oxygen-containing gas used in the C recovery period is such that air and inert gas are appropriately mixed to create and supply the required gas amount and oxygen content as desired.

In this case, it is assumed that there is a separate inert gas production device as a source of inert gas, although it is not shown in FIG.

However, there is a way to omit such additional equipment.

This is a method in which the gas released outside the system by the oil separator 8 is guided to the valve 20 and reused.

According to this method, a gas circulation system for the C recovery system is created, and the combustion gas is constantly circulated by the compressor 7. When the C recovery period starts, the valve 19 is opened as necessary to replenish air.

An amount of combustion gas corresponding to the amount of supplied air needs to be released outside the system in order to maintain a predetermined pressure inside the system, and this is done by the pressure regulating valve 21.

[Brief Description of the Drawings] Figs. 1 and 8 show the carbonization system of the present invention, Figs. 2 and 3 show its operating method, and Figs. 4 and 5 show the carbonization system used in the present invention. The structure of the furnace is shown, FIG. 6 shows the Scheer oil recovery device of the carbonization furnace, and FIG. 7 shows the cleaning device of the Scheer oil recovery device.

Claims (1)

[Claims] 1. When recovering oil, gas, etc. by carbonizing oil-bearing minerals,
The basic functions of the carbonization process, such as preheating, carbonization, combustion (C recovery), cooling, and charging/discharging operations, are performed using at least three vertical furnaces equipped with charging and discharging devices for oil-bearing minerals. As necessary, one or two operations are assigned to each furnace, and the overall structure is designed to include all operations necessary for carbonization, and carbonization starts at the same time as each furnace finishes its assigned operations. A carbonization means that moves to the next operation according to the order of operations, and the overall picture is a carbonization means that continuously carbonizes oil-containing minerals, a means that extracts oil-containing carbonization gas from a furnace during preheating or carbonization operation, cools it, and separates the oil. and means for heating and recirculating the furnace during the preheating or carbonization operation;
After taking oil-containing high-temperature combustion gas from the furnace during combustion (C recovery) operation and heating the carbonized gas, a means for separating the cooling oil and an inert gas and air are mixed to produce any oxygen-containing gas, which is then combusted. A means for supplying the carbonization gas to the furnace during operation, a means for taking out a part of the carbonization gas before heating it, supplying it to the furnace during the cooling operation and preheating it, and then recombining it with the carbonization gas during the charging and discharging operation. 1. A method for carbonizing oil-containing minerals, characterized in that the furnace has a means for releasing into the atmosphere after combustion the gas released when the furnace is depressurized and maintained at atmospheric pressure at the initial stage of charging and discharging operations. 2. When supplying oxygen-containing gas to a furnace during combustion operation, it is supplied in the opposite direction to the gas flow direction in carbonization operation, for example, if it flows from the top to the bottom of the furnace in carbonization operation, it is supplied so that it flows from the bottom to the top of the furnace. A method for carbonizing an oil-bearing mineral according to claim 1. 3. Claim 1: After cooling and oil-separating the oil-containing horse oil combustion gas taken out from the furnace during combustion operation, the mixture is mixed with air according to the degree necessary for combustion operation and re-supplied to the furnace during combustion operation. A method of carbonization of the described oil-bearing minerals. 4 After completing the replacement of old and new oil-bearing minerals in the furnace that is being charged and discharged, cold carbonization gas is introduced into the furnace to wash and remove the fine powder contained in the newly charged oil-bearing minerals and discharged to the outside of the system. The carbonization method according to claim 1, which proceeds to a post-carbonization operation.