JPS58154796A - Partial oxidation of solid fuel/water slurry - Google Patents

Abstract

PURPOSE:To uniformly atomize solid fuel slurry in a furnace and to make a prolonged stable operation possible without causing trouble of clogging a burner, by mixing oxygen-free gas for admixture with a solid fuel/water slurry and supplying the mixture to the burner, in the titled partial oxidation. CONSTITUTION:In producing a synthetic gas (mixed gas rich in carbon monoxide and hydrogen) by injecting oxygen-rich gas and fuel/water slurry into a gasifier followed by partial oxidation of the latter, the fuel/water slurry is mixed with oxygen-free gas (gas for admixture) and then supplied to a burner. It is pref. to use as said solid fuel/water slurry one of about 50-75wt% concn. and of <=about 1,000cp viscosity, and to be mixed with a mixing gas such as nitrogen or carbon dioxide in an amt. of about 0.1-10pts.vol. per vol. of the slurry.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for partially oxidizing a solid fuel-water slurry to produce synthesis gas or fuel gas, which is a mixed gas of carbon monoxide and hydrogen.

Natural gas and LPG have traditionally been used as raw materials for producing synthesis gas or fuel gas using the partial oxidation method.

Heavy oils such as naphtha, crude oil, C heavy oil, and vacuum residue.

Coal etc. are used.

Among these, natural gas, LPG, naphtha, and crude oil are expected to lose their price competitiveness in the near future due to the problem of depletion of crude oil and the rising price of clean energy to combat pollution. On the other hand, there is a noticeable surplus of heavy oil due to energy conversion from major consumers in the steel, electric power, and cement industries to coal, and it has a much lower ash content than coal, making it easier to handle as a fluid fuel. Since it is relatively cheap considering the amount of gas used, it will still be used as a raw material for gasification for the time being. However, crude oil will become heavier in the future.

As the petroleum industry tends to adopt heavy oil cracking processes as a countermeasure to the trend toward lighter products, we cannot expect the surplus problem of heavy oil to be resolved in the near future and low prices to be achieved. However, when heavy oil is cracked, problems arise in the treatment of large amounts of petroleum coke and petroleum pitch that are produced as by-products.

Coal has also been partially used as a raw material for gasification, but when considering the construction of energy-saving plants in the future, conventional methods are inefficient and require highly labor-intensive plant designs.

At present, there are still technical issues due to the ash content in the raw materials, and it will take a considerable amount of time for full-scale practical application.

The aforementioned petroleum coke and petroleum pitch are solid fuels that are likely to be produced in increasingly large quantities as heavy oil cracking progresses worldwide. petroleum coke.

Petroleum pitches have an order of magnitude lower ash content than coal (usually 1
% or less) and has the advantage of high calorific value. On the other hand.

Petroleum coke has a softening point.1 Petroleum pitches have a softening point, but the softening point is extremely high at 130 to 290°C, and handling it as a fluid fuel requires expensive equipment and energy. be.

Therefore, to date, there are almost no commercial gasification plants that use these solid fuels as raw materials.

Applicant has developed a system containing high concentrations of these solid fuels.

We have already proposed a slurry preparation method that has long-term stability.

No. 56-53\788, No. 56-53789.

No. 56-569 '39, No. 56-58522.

No. 56-91559, No. 56-94560.

No. 56-134844, No. 56-159501).

The solid fuel slurry obtained by these preparation methods is
Like known fluid fuels such as heavy oil, it can be used as a raw material for a partial oxidation reaction.

In the case of conventional fluid fuels, in order to carry out the partial oxidation reaction,
As a moderating agent for the gasification reaction, steam is generally premixed with the fluid feedstock and supplied to the burner. On the other hand, in the case of solid fuel slurry, water as a moderator is already sufficiently entrained, and there is no need to add a moderator. Therefore, in the case of the slurry supply method compared to the conventional raw material supply method using steam, the flow rate when passing through the burner installed in the gasifier is significantly reduced. This means that
The residence time of the raw material inside the burner becomes significantly longer, and the water in the slurry evaporates inside the burner.

The solid fuel partially solidifies, causing drifting in the burner or blockage of the burner, resulting in a significant decrease in operational stability and gasification reaction efficiency.

At the same time, the slurry supply pressure may rise abnormally, causing trouble in the charge pump and slurry piping.

Particularly, solid fuels such as petroleum pitch, which have a softening point, may partially melt and adhere in the burner. Especially at the start of the gasification reaction, the temperature is usually 9.

First, a gasifier is installed in a gasifier heated to a predetermined reaction temperature, and then gasification raw materials and oxygen are supplied at a predetermined flow rate.
After adjusting the temperature and pressure, a method is adopted in which the material is supplied to a cooler. During the so-called adjustment period from installation of the burner to the trench supplying gasification raw materials and oxygen, the burner is exposed to the high temperature of the furnace. Burner blockage is likely to occur due to solidification of petroleum pitches due to rapid evaporation of water. Therefore, by turning the solid fuel into a slurry, it can be handled in the same way as conventional fluid fuel, but only up to the point where it is supplied to the burner, and the flow state inside the burner is completely different. Redesigning burners to match the flow rate of the slurry to the flow rate of conventional fluid fuel and moderator mixtures is nearly impossible due to flow resistance.

The object of the invention is to provide a method for partial oxidation of solid fuel slurries that does not have the above-mentioned disadvantages.

That is, the present invention is a partial oxidation method for partially oxidizing a solid fuel-water slurry with an oxygen-containing gas, which is characterized in that a mixing gas that does not contain oxygen is mixed with the solid fuel slurry and supplied to a burner. be.

According to this invention, the flow rate and residence time of the solid fuel slurry in the burner can be arbitrarily controlled by adjusting the amount of gas for mixing.

Excellent effects are achieved in that the burner is not clogged, and the solid fuel slurry is uniformly dispersed by the mixing gas and sprayed uniformly into the gasifier.

Specific examples of solid fuels include petroleum pitch and petroleum coke, which are the decomposition residues of heavy oil. Preferably, the petroleum pinch has a softening point (measured according to J. K. 8, 2207-1980) of 100° C. or higher, especially in the range 130-290° C.

As mentioned above, petroleum coke does not have a softening point.

According to the wet method, the solid fuel is ground in a known grinding machine such as a base mill, disc mill, or ball mill in the presence of water containing a surfactant such as an alkali metal salt of lignin sulfonic acid or an alkaline earth metal. It can be prepared by the grinding method. After dry crushing the solid fuel, which is not always an advantageous method.

A slurry may be prepared by mixing with water containing a surfactant.

The solid fuel-water slurry has a 14 mesh sieving rate of 100
%, and the 200 mesh sieving rate is at least 70q6
and that the particle size distribution curve in the particle size diagram of Garrosin Rammler has a slope of 1 or more (hereinafter referred to as the slope of the particle size distribution curve).

Slurry: Preferable in terms of facilitating pumping and supply to the burner and increasing gasification efficiency.

In addition, the solid fuel concentration in the solid fuel-water slurry is 50~
In view of the above, it is preferable that the content is 75% by weight and the viscosity is 1000 cp or less.

Specific examples of the mixing gas include carbon dioxide gas, nitrogen gas, synthesis gas or fuel gas produced by partial oxidation, or a mixed gas thereof.

Oxygen-containing gas cannot be used as a mixing gas for safety reasons. The amount of mixing gas mixed into the solid fuel-water slurry is per 1 part by volume of the slurry.

The flow rate under partial oxidation conditions, that is, the actual flow rate, is 0.1 to
Preferably it is 10 parts by volume, especially 1 to 5 parts by volume.

If the mixing amount of the mixing gas is less than the lower limit, it will be difficult to achieve the desired effect, and even if it exceeds the upper limit, no difference in effect will be observed.
Carbon dioxide gas as a mixing gas.

When nitrogen gas is used, it often becomes an unnecessary gas in subsequent steps.

There are no particular restrictions on where the mixing gas is mixed with the solid fuel-water slurry, but from an industrial perspective.

It is preferable to mix the slurry with the mixing gas immediately before feeding it to the burner. There is no particular restriction on the mixing method, and a mixing method using a mixer, a mixing method using a T-shaped or Y-shaped pipe, etc. can be adopted.

The partial oxidation reaction of the solid fuel-water slurry can be carried out under the same conditions as those of known heavy oils.

Specific examples of oxygen-containing gases include air, oxygen-enriched air,
Examples include high purity oxygen.

The reaction temperature is usually 980-19001? : and the reaction pressure is usually 10 to 250 Kf/-.

Examples and comparative examples are shown below. The properties of the slurry of petroleum coke or petroleum pitch and water used in the Examples and Comparative Examples are shown in the table below.

14 mesh sieving rate (support)) 1oo 1o.

200 mesh sieving rate (a) 90.5 9
1.1 Slope of particle size distribution curve 1.1 +
, 1 solid fuel concentration (wt%) 58.7
60.6 Slurry viscosity (cp) 113 15
0 Softening point (°C) -230 Example 1 A gasification furnace with an inner diameter of 84 crn and a height of 3 oocrr1 was
After preheating to 00℃, use a double tube structure burner.

A burner with an inner tube diameter of 10111 + an outer tube diameter of 1 sw at the tip was attached to the gasifier, and carbon dioxide gas at 15° C. was passed through the burner outer tube at a rate of 3'ON/hour.

60 minutes after the start of the flow of carbon dioxide gas, a 18°C petroleum coke-water slurry was added from the burner outer pipe together with the above amount of carbon dioxide gas for 1.08y/hour, and 95°C oxygen was added from the burner inner pipe for 5 a ONFF? /hour, respectively, feed into the cassifier 1. The partial oxidation reaction of petroleum coke was started at 1380°C and 25 kg/clA. The pressure of carbon dioxide gas just before the burner supply port is 29V4/cA, and the oxygen pressure is 27V4/cA.
It was /-. Therefore, the actual flow rate of carbon dioxide gas mixed with 9 petroleum coke-water slurry is 1. It was o9m'/hour.

Although the partial oxidation reaction was continued for 10 hours, no fluctuations in the supply pressure and flow rate of the petroleum coke-water slurry were observed. After the reaction was completed, the burner was removed and inspected, but no deposits were observed.

Comparative Example 1 Example 1 was repeated except that the supply of carbon dioxide gas was stopped 60 minutes after the start of the partial oxidation reaction.

After stopping the supply of carbon dioxide gas, the supply pressure of the petroleum coke-water slurry started to rise, and after 1.6 hours it reached 35Kg/
cIA reached 40 to 9/- after 1.5 hours. After that, when 3ONyy//hour of carbon dioxide gas was mixed with the slurry and supplied to the burner, the supply pressure was 35Kg/-
However, it did not decline further than that. When the burner was inspected after the reaction was completed, a portion of the burner tip was blocked with petroleum coke.

Comparative Example 2 Example 1 was repeated except that the reaction was carried out under the following reaction starting conditions without supplying carbon dioxide gas to the petroleum coke-water slurry from the start of the partial oxidation reaction.

Oxygen 650 N-7 hours 28
Twenty minutes after the start of the 96 partial oxidation reaction, the slurry flow rate suddenly decreased, so the 9 reaction was stopped. When the burner was inspected, it was found that the slurry spouting part at the tip of the burner was almost completely blocked.

Example 2 Instead of petroleum coke-water slurry, petroleum pitch-water slurry was supplied at 1.09 m"7 o'clock, and the flow rate of carbon dioxide was s
o Example 1 was repeated except that Nrd was changed to 1 hour (actual flow rate: 1.82 m'/hour).

Although the partial oxidation reaction continued for 6 hours, there were no fluctuations in the slurry supply pressure or flow rate. After the reaction was completed, the burner was inspected, but no deposits were found.

Six hours after starting the first reaction, synthesis gas produced in the reaction was used instead of carbon dioxide gas, but the same results as above were obtained.

Comparative Example 3 Example 2 was repeated except that carbon dioxide gas was not mixed into the petroleum pitch-water slurry from the start of the partial oxidation reaction, and the amount of oxygen supplied was 4101 hours.

40 minutes after the start of the partial oxidation reaction, the slurry supply pressure suddenly rose to 60 Ky/- or more, so 9 reactions were stopped. When the burner was inspected, it was found that the slurry flow path of the burner was almost completely blocked, and petroleum pitch was welded to the tip.

Patent applicant Ube Industries Co., Ltd.

Claims (6)

[Claims] (1) A method for partially oxidizing a solid fuel-water slurry with an oxygen-containing gas, the method comprising: mixing an oxygen-free mixing gas with the solid fuel-water slurry and supplying the mixture to a burner. (2) The partial oxidation method according to claim 1, wherein petroleum coke or petroleum pitch is used as the solid fuel. (3) As a solid fuel-water slurry, the sieving rate of 147 7 units is 100 units, the 200 units sieving rate is at least 70 units, and the particle size distribution curve in the Rosin Rammler particle size diagram is 1 or more. The partial oxidation method according to claim 1, which uses a slurry of petroleum coke or petroleum pitch and water having a gradient of . (4) The concentration of petroleum coke or petroleum pitch is 50-7
5% by weight and a slurry viscosity of 1000 cp or less. (5) Nitrogen gas and carbon dioxide gas as mixing gas. 2. The partial oxidation method according to claim 1, wherein one or more gases selected from gases generated in partial oxidation are used. (6) The mixing amount of the mixing gas is solid fuel-water slurry-1
The partial oxidation method according to claim 1, wherein the amount is 0.1 to 10 parts by volume.