JPS6011957B2 - Gasification method for solid carbon feedstock containing hydrocarbons - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for gasifying a solid carbon raw material containing hydrocarbons such as coal (hereinafter simply referred to as "solid carbon raw material") using a molten inorganic oxide.

Due to the limited reserves of petroleum-based hydrocarbon resources, countries around the world are developing processes for gasifying solid carbon materials, especially coal, to obtain fuel or chemical raw materials.

One of the typical methods conventionally used for this purpose is the thermal decomposition (carbonization) method using a coking oven, but another method is the molten bed method. In this molten bed method, steam and coal are mixed together in a high-temperature molten heat medium.
Gasification is performed by introducing a gasification agent such as oxygen or air.

When water vapor is introduced, a water gas whose main components are CO and 2 is produced by a water gas reaction, and when oxygen or the like is introduced, a fuel gas whose main components are CO is obtained by partial combustion. In addition, attempts are being made to explore the balance of heat by introducing water vapor and oxygen at the same time. And this method is
The gasification rate is high because of the good contact state between the solid carbon raw material and the heat medium; it has excellent properties such as being compatible with variations in the properties of the solid carbon raw material. However, the produced gas obtained by such a molten bed method is
It is a low-calorie gas whose main components are CO2, etc., and if it is processed through a CO conversion and methanation process, it can be converted into a high-calorie gas called SNG, which is equivalent to natural gas. The fact that a process is required is not necessarily advantageous in terms of energy.

An object of the present invention is to provide a method for recovering more useful gas fuels and chemical synthesis raw materials from solid carbon raw materials as efficiently as possible while maintaining the advantages of the molten bed method as described above.

That is, coal and other solid carbon raw materials themselves contain hydrocarbons. According to the findings of the present inventors, when thermal decomposition (carbonization) is carried out by direct contact with a molten heat medium, the aspect is different from the slow thermal decomposition reaction of the secondary reactor, and the
At a considerably high yield of 50%, it produces cracked gas and cracked oil that can be used as high-calorie fuels or raw materials for chemical synthesis. The remaining liquid can serve as a suitable raw material for the water gas reaction described above. By first allowing the thermal decomposition reaction to proceed as much as possible for the solid carbon raw material, and then performing the water gas reaction on the solid residue, it is possible to recover the gaseous or liquid carbon raw material more efficiently as a whole. In this case as well, the advantage of the high contact efficiency of the molten bed method can be effectively utilized. and,
The heating source for the heat carrier necessary to maintain the conditions for the pyrolysis reaction and water gas reaction, both of which are endothermic reactions, uses an oxidation-stable inorganic oxide as the heat carrier, and burns the solid residue in the reactor. This allows the amount of heat generated to be used effectively. The method of gasifying a solid carbon raw material using a molten inorganic oxide as a heat medium according to the present invention is based on the above-mentioned technical concept, and more specifically includes the following steps.

'1} The solid carbon raw material is introduced into the heat medium bath in the reaction tank placed at the thermal decomposition reaction temperature of the solid carbon raw material, decomposed in direct contact with the heat medium, and the cracked gas is recovered while the heat medium is heated. A process of leaving a solid residue in the heat exchanger, ■ A process of partially burning the solid residue and heating the heating medium to the water gas reaction temperature, and '3' A process of introducing water vapor into the heating medium and leaving a solid residue The process of carrying out a water gas reaction between

Hereinafter, the present invention will be explained in more detail with reference to the drawings.

FIG. 1 is a side sectional view of an example of a reaction tank in the solid carbon raw material gasification method of the present invention, and FIG. 2 is a process diagram of an example of the apparatus including a post-processing step. In the present invention, the inorganic oxides used as heat carriers in a molten state include Si02, Na20, MaC, Ca0, M
It is a mixture of oxides such as g0, O○, Pbo, B203, and Zno, and partially carbonated oxides are also used.

By appropriately selecting the composition of these inorganic oxides, the thermal decomposition of coal and water gas reaction temperature can be adjusted to 9.
00 to 150,000, it is possible to provide a molten heat medium with a sufficiently low viscosity (1 oise or less). For example, mixtures having the following compositions all have softening points of 70 pi or less and are examples of preferred low-viscosity melting heat transfer media (compositions are expressed in weight %). Table 1 The method of the present invention can use solid carbon raw materials having a wide range of properties including fixed carbon, volatile content, ash content, and other contents.

Generally, volatile content of 10 to 5-value cloud amount% (JISM8812,
Coal having a component that gasifies up to 925 qC is preferable, but low-volatile pitch obtained from petroleum green coke, petroleum heavy oil, coal, oil shale, tar sand, etc. containing this level of volatile content is also suitable. Can be used as raw material. The following is an example of the properties of coal, which is a typical bagged raw material. Table 2 *The part of dry charcoal excluding ash content is taken as 100.

Hereinafter, embodiments of the present invention will be described by taking gasification of raw coal as an example. According to Figure 1, 900-150
Pulverized raw coal is charged from a pipe 3 into a reaction tank 2 containing a heat medium 1 maintained at a thermal decomposition reaction temperature of 0 qo, preferably 1100 to 1300 q0.

The pulverized coal may be charged by pyrolysis or by circulating and injecting water gas reaction product gas, or by blowing into the pulverized coal 20 to 50% by weight of oil (e.g., pyrolysis distillate obtained by the method of the present invention). A method of mixing heavy oil such as oil, petroleum-based vacuum residual oil, etc. to form a slurry and introducing the slurry is preferably used. The amount of heat medium in the reaction tank 2 is determined based on the raw coal charge amount lk9' from the viewpoint of contact time and thermal decomposition reaction duration time.
It is preferable to set it to 12k9 or more with respect to hr. This produces about 45-55% by weight of the raw coal of CH4-rich cracked gas and cracked oil, and about 45-55% by weight of coke solid residue.

As the reaction continues, the heat medium temperature decreases and coke builds up in the heat medium. For this reason, charging of coking coal is
The temperature is 50-300℃, preferably 100-200qo
, or if the produced coke increases the viscosity of the bath, the process is stopped before the coke solid residue reaches 8% by weight of the heating medium amount. Therefore, the initial temperature of the heat medium bath is set to 1100, taking this temperature drop into account.
It is preferable to adopt 00 to 1300o○. Next, the reduced railway line area is reduced to 1000 to 1500, preferably 1100 by partially burning the accumulated coking solid residue.
Heat to water gas reaction temperature of ~1300 pm.

Combustion of the solid bamboo is carried out by blowing air or oxygen through the pipe 4, but if necessary, the fuel can also be combusted using the nozzle 5 disposed above the pipe 1 in the reaction tank. Heating can be achieved by burning coke corresponding to about 50-7% by weight of the produced coke, but as mentioned above this amount can be reduced by auxiliary combustion in nozzle 5. When the temperature has recovered to the water gas reaction temperature, combustion of the coking solid residue is stopped, and superheated steam is introduced from the pipe 4 to cause a water gas reaction with the solid residue.

This gives an approximate composition of &52% by volume, C04
Water gas having a composition of % by volume and % by volume of C0 can be obtained at a rate of about 1.5 kg per coke.
As the water gas reaction progresses, the bath temperature decreases, but 100
The water gas reaction is completed by the time the temperature reaches 0°C, preferably 1100 qo. As another embodiment of the combustion of residual coke and the water gas reaction, oxygen can be introduced together with superheated steam to partially burn the coke and prevent the temperature from decreasing. As an example, about 55% by weight of coking coal
If about 1 box weight % of the remaining coke (containing about 4 weight % ash content based on raw coal) is consumed in a water gas reaction, for example, 3 k9 of steam at 150°C per 1 kg of coke
, 02 blur can be used. After the water gas reaction is completed, the unreacted coke is combusted by blowing air through the pipe 4, and if necessary, the combustion is combusted by the /zuru 5 to bring the ordinary temperature lowered by the water gas reaction to the pyrolysis reaction temperature. Recover.

In addition, if partial combustion is used in the water gas reaction and the coke cost is completely consumed during the water gas reaction, the temperature of the heating medium can be maintained without the need for an independent residual coke combustion process after the water gas reaction. The thermal decomposition reaction can proceed immediately. After combustion of the coking, ash is mixed into the hot soot bath, depending on the type of coal, about 3 to 3 tonne weight percent of the raw coal, usually 5 to 1 weight percent. This ash content is Si022
5-6 wt%, AI20315-35 wt%, Fe2
In addition to 035 to 25% by weight and 01 to 15% by weight of Ca, it contains small amounts of Mg0, Na20, K20, etc., and its melting point is generally between 1200 and 1500oo. Therefore, such ash can occupy a part of the molten heat transfer medium in the present invention. However, regarding the ash content accumulated in the furnace, the heating medium is extracted from the piping 6 or 7 provided on the side wall or bottom of the reaction tank as appropriate depending on the grade level and composition change, and the new inorganic Supply oxide. The gaseous products produced by the above method as well as the after-treatment gas are treated by conventional after-treatment systems.

FIG. 2 is a process diagram of an example of an apparatus for implementing the present invention including such a post-treatment system. The generated gas from the reaction tank 2 first enters the heat exchanger 10 through the pipe 9, where the waste heat is recovered and the high boiling point decomposed crab oil condensed at the bottom is transferred to the heat exchanger 10.
The exhaust gas from the heat exchanger 10 is recovered from the
The liquid product enters the condenser 12, where light cracked oil mainly produced during the pyrolysis process and unreacted water vapor from the water gas reaction process are recovered by a liquid product recovery device 13. The outlet gas of the condenser 12 has a significantly different composition in each step of the process according to the invention. Therefore, the exhaust gas from the pyrolysis process is collected in the pyrolysis gas recovery device 14, the combustion exhaust gas is collected in the exhaust gas treatment system or atmospheric release system 15, and the exhaust gas from the water gas reaction process is collected in the water gas recovery device 16. Ru. The pressure in the reaction tank is from normal pressure to about 10 atm, taking into consideration the pressure loss in the post-treatment system.
In the above example, since there is only one reaction tank, the product from the process is not constant over time, but by arranging a plurality of reaction tanks in parallel, changes over time can be considerably smoothed out.

An example of the material balance per n of raw coal 1 when raw coal (Miike charcoal) is treated by the method of the present invention is as follows.

(Coking coal is charged into the reaction tank by circulating pyrolysis gas, but the contribution of that pyrolysis gas is excluded from the table below.) Pyrolysis oil production amount 72k
g Pyrolysis gas 〃 517N (approx. 381
k9) Amount of remaining coal after pyrolysis (excluding ash) 511
K9 combustion coal amount (after pyrolysis) 306k
g〃 (After water gas reaction) 139k9 steam introduction amount 201k9 water gas reaction consumption coke amount 66kg water gas production amount
36 By adopting a method of effective utilization, the following characteristics arise.

'11 Processing efficiency is high because a molten inorganic oxide that is stable at high temperatures is used as a heat medium and brought into direct contact with the solid carbon raw material while exhibiting good fluidity.

■ Due to the high contact efficiency, especially in the first pyrolysis step, cracked gas and cracked oil, which are particularly useful as chemical raw materials and for high-calorie combustion, can be recovered in a high ratio relative to coking coal. '31 Maximum gasification is possible by performing a water gas reaction using residual coke after thermal decomposition as a raw material.

■ Since all produced gases are recovered individually, they can be used effectively by taking advantage of their characteristics.

'51 Thermal efficiency is high because residual coke whose value has decreased after pyrolysis is partially combusted and effectively used as a heat source for pyrolysis reactions and water gas reactions.

'61 Since the heat transfer medium is stable against oxidation, even if residual coke is burned in the reaction tank, it will not change in quality.

The generated ash is of the same quality as the heating medium, so it can be used as is as part of the heating medium.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of an example of a reaction tank for implementing the gasification method of the present invention, and FIG. 2 is a process diagram of an example of an apparatus including a post-processing step for implementing the gasification method of the present invention. be. 1... Melting heat medium, 2... Reaction tank, 3
... Coking coal charging pipe, 4 ... Steam, oxygen and air introduction pipe, 5 ... Fuel combustion nozzle, 6, 7 ... Heat medium extraction pipe, 8...
・Heating medium supply nozzle, 9...Produced gas discharge pipe, 10
... Heat exchanger, 12 ... Condenser, 14
... Pyrolysis gas recovery device, 15 ... Combustion gas treatment system, 16 ... Water gas recovery device. Multi J picture scroll 2

Claims (1)

[Scope of Claims] 1. A method for gasifying a hydrocarbon-containing solid carbon raw material using a molten inorganic oxide as a heat medium, which includes the following steps. (1) The solid carbon raw material containing hydrocarbons is introduced into a heat medium bath in a reaction tank placed at the thermal decomposition reaction temperature, and is decomposed in direct contact with the heat medium bath to produce cracked gas. The process of recovering solid residue and leaving a solid residue in the heat medium bath (
2) Partial combustion of the solid residue to heat the heat transfer medium to a water gas reaction temperature; and (3) Step of introducing water vapor into the heat transfer medium to perform a water gas reaction with the remaining solid residue.