High temperature solvent pretreatment method for improving yield of direct sodium-rich coal liquefaction oil

Technical Field

The invention relates to a high-temperature solvent pretreatment method, in particular to a direct coal liquefaction oil rich sodium is suitable for improving the yield of the high-temperature solvent pretreatment method.

Background Art

My fat coal, lean oil, the quantity of the National conditions determine the coal in our energy system plays an important role in, in the various types of coal in, in order to brown coal and bituminous coal as the representative of the low-rank coal, its reserves also is the highest. According to authoritative sector statistics, low-rank coal reserves in China have proven reserves of coal resources (about 10200 million tons) of 55% the left and the right, there is the volatile content of about equivalent to 1000 million tons of oil and gas resources. It can be predicted that, in the future for quite a long period of time, effective and clean utilization of low rank coal in the protection of my energy security, provide a lasting energy supply and other aspects will play an important role.

Coal of low rank coal direct liquefaction is effective and clean utilization of the important ways, through the direct liquefaction technology, the low value-added low-rank coal conversion with higher value liquid fuel and chemical raw materials, has major strategic significance. In recent years, in my Xinjiang assignments were found a block of low-rank coal resources reserves enriching region, the initial forecast coal reserves up to 3900 million tons, the accumulated proven reserves of coal resources more than 2000 million tons. The discovery and use of coal for assignments, greatly eased China's current energy consumption of the tense and energy supply situation of insufficient. To calculate the annual consumption of my existing coal, coal can be used for my use assignments about hundred.

For assignments with high volatile coal, high reactivity and low ash content and the like, is direct coal liquefaction technology high-quality raw materials. However on the other hand, the ash content of coal assignments although relatively low, but its ash contains a large amount of alkali metal and alkaline earth metal, in particular sodium ion, sodium ion content in the coal assignments can account of the total amount of ash content of 10% or more, which belongs to the typical high sodium coal. According to the existing form of different, assignments in the coal sodium ion can be divided into three categories, the water-soluble sodium ion (such as dissolved in water is sodium chloride), can be exchange sodium ion (such as with the coal in the organic oxygen-containing functional group combining sodium ion) and aluminosilicate sodium ion. Because of geological conditions and the cheng Meicheng Mei environmental reasons, assignments in the coal containing more of the sodium ion in the exchangeable sodium ion. Research shows that, can be exchange sodium ion to the low-rank coal direct liquefaction reaction of impact is negative, this negative impact is mainly embodied in two aspects: can exchange sodium ion can be through the promotion of direct liquefaction of coal pyrolysis the generation of free radicals, increase the yield of by-product liquefied residue; at higher direct liquefaction under lower reaction temperature conditions, can be exchange with the sodium in the coal to clay such mineral reaction, generating drossy material has very strong cohesiveness, easy adhesion in the reactor interior, impede the reactor heat transfer and increase the difficulty of the product discharged from the reactor. The above these negative factors greatly limits the direct liquefaction of coal in the assignments in the application, so the development of a process is simple, can improve the assignments to coal as representative high sodium coal direct liquefaction oil pretreatment method of yield, to promote high sodium coal and coal and the like assignments in the direct liquefaction technology in application of important practical significance and economic value.

Content of the invention

The technical problem: the purpose of this invention is directed to the problems existing in the prior art, provides a method for increasing the yield of the rich sodium coal direct liquefaction of the high-temperature solvent pretreatment method, by direct liquefaction after reaction, most of the sodium in the coal will remain in the direct liquefaction of the by-product in the liquefied residue, water solubility of the sodium ion is directly liquefied residue gasification good catalyst, rich in water-soluble sodium ion of the liquefied residue in the gasification will also have very high transfers the efficiency, direct liquefaction the economy of the process is further optimized.

The technical proposal: the invention improve the rich sodium direct coal liquefaction oil yield of the high-temperature solvent pre-processing method, comprising the following steps:

A. The raw coal crushing processing, after being broken from crowding and ternary composite solvent in the reactor after the blending, the use of ultrasonic oscillation 10 - 20min, crushed coal and ternary composite solvent quality inputs to the ratio of 2:1 - 1:1;

B. The flow of bath the fast heating of the reactor, the resulting mixed slurry in the 200 - 250 °C solvent under the conditions of heat treatment, the heat treatment time is 20 - 40min, flow bath rapid heating in the reactor of the atmosphere is an inert atmosphere;

C. After the heat treatment of the mixed slurry after the natural cooling, through centrifugal precipitation method to separation, the separated solvent recovery for follow-up after the liquefaction of the experiment;

E. The obtained after separating the coal low-temperature drying, and sealing storage is placed at the bottom of the color-changing silica gel desiccant in the container;

F. Drying good coal direct liquefied experiment, direct liquefaction experimental conditions: coal and solvent mass ratio is 1:1, the reaction temperature is 400 - 450 °C, the reaction atmosphere is hydrogen, cold pressing for 2 - 5 mpa, reaction time 40 - 60min.

The crushing of the coal particle size of less than 150 μm.

The three-component composite solvent is hydrogen solvent, non-hydrogen combination of solvent and ferrous sulfate solution; wherein the hydrogen solvent of the solvent with the non-hydrogen mass ratio of 2:1 - 1:1, the hydrogen solvent and ferrous sulfate solution and the mass ratio of 20:1 - 30:1.

The solvent is tetrahydronaphthalene or dihydrophenanthrenestates for the hydrogen in a, non-hydrogen solvent is 1 - methyl naphthalene in a, ferrous sulfate concentration of solution 0.10 - 0.15 mol/L.

The reactor for tube ball type reactor or in a high pressure autoclave.

The ultrasonic vibration frequency is 40 - 60kHz.

The flow bath fast heating the heating rate is 80 - 100 °C/min.

The inert atmosphere is nitrogen or argon, the atmospheric pressure is 0.5 - 1.0 mpa.

The low-temperature drying treatment is vacuum drying, the drying temperature is 40 - 60 °C, drying time 6 - 10h.

The advantages: because of the coal in the structure of the organic macromolecule, can be exchange of sodium ion is characterized in that the part of the sodium in the coal through the ionic bond with the oxygen-containing functional group, such as carboxyl group and combine with the hydroxide, it has stronger active and reactive. In the suitable temperature conditions, some weak chemical bond in the coal will rupture, carboxyl that is of a kind which, in 200 °C the left and the right, in the coal can be broken carboxyl functional group, generating coal pyrolysis free radical debris. This invention adopts the pretreatment in the method, coal in the 200 - 250 °C, hydrogen solvent can occur under the presence of a decarboxylation reaction, accompanied by the organic structure of the coal in the occurrence of decarboxylation reaction, connected with the carboxyl group of the sodium ion in the form of pronunciation will also with changing, decarboxylation reaction can exchange sodium ion with the coal to the organic structure is separated from the, changes to the water-soluble sodium ions, water solubility of the sodium ion to the low-rank coal direct liquefaction reaction product is distributed less affected, and high temperature is not easy with the coal in the aluminosilicate mineral reaction, enabling the exchange of sodium ion to be direct liquefaction reaction the adverse influence of the, so the oil receives rate direct liquefaction of the reaction will be increased, at the same time the service life of reactor can be prolonged. In addition, the ternary mixed solvent reaction system, the hydrogen solvent in this high-temperature solvent in the pre-treatment process can be not only can promote exchange of sodium ion to the water-soluble sodium ion changes, can also play the role of the partial hydrogenation, so that the hydrogen content of the coal in the structure has increased, the hydrogen-rich coal structure to the follow-up liquefied experiment is very favorable; non-hydrogen solvent in this process has promote hydrogen transfer and optimized hydrogen distributed function, can enhance the hydrogen supplying the solvent hydrogenation effect; ferrous sulfate solution is directly liquefied reaction catalyst, in this process can be highly uniformly dispersed in the mixture within the system, in the follow-up of the direct liquefaction in the experiment to have better and more catalytic effect. After the coal is mixed with a solvent, ultrasonic oscillation processing of the coal and the dispersion degree of the within the solvent, the solvent into contact with the coal more fully. In the process of heating the reactor, the flow of bath fast raising method, can effectively shorten the treatment time, the increase in the unit time of the coal handling capacity, at the same time slowly raising can also avoid the occurrence of the slag in the course of the reaction. The inner atmosphere of the reactor used is an inert gas, such as argon or nitrogen, and the pressure is 0.5 - 1.0 mpa, the reaction process can be effectively reduce the cost. The high-temperature solvent after pre-treatment, the used solvent after separation without waste processing, in the follow-up of the direct liquefaction in the experiment can be used as a direct liquefaction solvent additive to continue to use, this from the raw material used is greatly reduced the cost of the reaction.

Direct liquefaction after reaction, most of the sodium in the coal will remain in the direct liquefaction of the by-product in the liquefied residue, water solubility of the sodium ion is directly liquefied residue gasification good catalyst, rich in water-soluble sodium ion of the liquefied residue in the gasification will also have very high transfers the efficiency, direct liquefaction the economy of the process is further optimized. As the choice of the solvent pre-processing temperature, high temperature means that the reactor tolerance and reaction the increase of the cost, by a large number of pre-processing temperature after the experiment summarized found most suitable for the pre-treatment temperature in the 200 - 250 °C, the pre-treatment temperature sections, not only can achieve the purpose of the pretreatment, but also the maximum reduction of the cost of the reaction. The experiment still attempt to a plurality of pretreatment and combination of the solvent, includes polar solvent, non-polar solvent, aliphatic solvents and aromatic solvent or the like, by comparing the various combined solvent processing after the liquefaction of coal yield, the final ternary mixed solvent of the best effect. Through the invention of the high-temperature solvent after pre-treatment, high sodium direct liquefaction of the oil receives rate can improve the 10% - 13% (dry ash-free base), can improve the overall conversion rate of 15% - 18% (dry ash-free base), it has good industrial value and application prospect. The operating procedure is simple, the raw material of the high usage rate, to yield as the promotion action is obvious, and is easy for industrial scale, with very good application prospects.

Mode of execution

The present invention improve the rich sodium direct coal liquefaction oil yield of the high-temperature solvent pretreatment method, specific steps are as follows:

A. The raw coal crushing processing, after being broken from crowding particle size of less than 150 μm, the crushed from crowding and ternary composite solvent blend in the reactor, the reactor for tube ball type reactor or in a high pressure autoclave. After, the use frequency is 40 - 60kHz ultrasonic oscillation 10 - 20min; the from crowding and ternary composite solvent quality inputs to the ratio of 2:1 - 1:1; the three-component composite solvent is hydrogen solvent, non-hydrogen combination of solvent and ferrous sulfate solution; wherein the hydrogen solvent of the solvent with the non-hydrogen mass ratio of 2:1 - 1:1, the hydrogen solvent and ferrous sulfate solution and the mass ratio of 20:1 - 30:1; the solvent is tetrahydronaphthalene or dihydrophenanthrenestates for the hydrogen in a, non-hydrogen solvent is 1 - methyl naphthalene in a, ferrous sulfate concentration of solution 0.10 - 0.15 mol/L;

B. The flow of bath the fast heating of the reactor, the flow bath fast heating the heating rate is 80 - 100 °C/min. The resulting mixed slurry in the 200 - 250 °C solvent under the conditions of heat treatment, the heat treatment time is 20 - 40min, flow bath rapid heating in the reactor of the atmosphere is an inert atmosphere, the inert atmosphere is nitrogen or argon, the atmospheric pressure is 0.5 - 1.0 mpa;

C. After the heat treatment of the mixed slurry after the natural cooling, through centrifugal precipitation method to separation, the separated solvent recovery for follow-up after the liquefaction of the experiment;

E. The obtained after separating the coal drying at a low temperature, low-temperature drying treatment is vacuum drying, the drying temperature is 40 - 60 °C, drying time 6 - 10h; after, sealing storage placed at the bottom of the color of the silica gel desiccant in the container;

F. Drying good coal direct liquefied experiment, direct liquefaction experimental conditions: coal and solvent mass ratio is 1:1, the reaction temperature is 400 - 450 °C, the reaction atmosphere is hydrogen, cold pressing for 2 - 5 mpa, reaction time 40 - 60min.

Embodiment 1,

Raw coal by crushing processing, crushing particle size of less than 150 μm, in order to mass ratio is 1:1 ratio of the crushed from crowding with the mixed solvent (tetrahydronaphthalene, naphthalene, 0.10 mol/L ferrous sulfate solution) into the tube spring in the reactor, ultrasonic oscillation processing 15min. Then, in the 80 °C/min of the rate of rise of the reactor under the temperature to 220 °C, pretreatment time is 30min. After the processing of the mixed slurry through centrifugal precipitation method to separate, and the recovered solvent to continue for subsequent liquefaction experiment. After the separation of the coal in the treatment of 40 °C lower vacuum drying 6h seal keeps after the. Direct liquefaction experiment in 420 °C and 3 mpa under hydrogen pressure conditions, with the crushing of the compared with the coal crushing, solvent after the heat treatment processing coal, its liquefied oil yield has been raised by 10.5%, improving the conversion rate of 15.6%.

Embodiment 2,

Raw coal by crushing processing, crushing particle size of less than 150 μm, in order to mass ratio is 2:1 the proportion of coal with the mixed solvent (b hydrogen Philippines, naphthalene, 0.12 mol/L ferrous sulfate solution) into the high-pressure in the reactor, ultrasonic oscillation processing 15min. Then, in order to 100 °C/min at a heating rate of heating a reaction kettle to 230 °C, time is 30min. After the processing of the mixed slurry through centrifugal precipitation method to separate, and after the recovery of the solvent for continued follow-up liquefied experiment. After the separation of the coal in the treatment of 50 °C lower vacuum drying 8h seal keeps after the. Coal direct liquefaction experiment in the 440 °C and 3 mpa under hydrogen pressure conditions, with the crushing of the compared with the coal crushing, solvent after the heat treatment processing coal, its liquefied oil yield has been raised 12.6%, the conversion rate of 16.3%.

Embodiment 3,

Raw coal by crushing processing, crushing the particle size smaller than 100 μm, in order to mass ratio is 1.5: 1 ratio of coal with the mixed solvent (b hydrogen Philippines, 1 - methylnaphthalene, 0.15 mol/L ferrous sulfate solution) into the high-pressure in the reactor, ultrasonic oscillation processing 20min. Then, in order to 100 °C/min heating rate of the heating a reaction kettle to 230 °C, pretreatment time is 40min. After the processing of the mixed slurry through centrifugal precipitation method to separate, and the recovered solvent to continue for subsequent liquefaction experiment. After the separation of the coal in the treatment of 50 °C lower vacuum drying 6h seal keeps after the. Coal direct liquefaction experiment in the 440 °C and 2 mpa under hydrogen pressure conditions, with the crushing of the compared with the coal crushing, solvent after the heat treatment processing coal, its liquefied oil yield has been raised 11.3%, conversion and improves the 15.5%.

Embodiment 4,

Raw coal by crushing processing, crushing the particle size smaller than 100 μm, in order to mass ratio is 2:1 the proportion of coal with the mixed solvent (tetrahydronaphthalene, 1 - methylnaphthalene, 0.15 mol/L ferrous sulfate solution) into the tube spring in the reactor, ultrasonic oscillation processing 20min. Then, in order to 95 °C/min of the rate of rise of the reactor temperature to 250 °C, pretreatment time is 40min. After the processing of the mixed slurry through centrifugal precipitation method to separate, and the recovered solvent to continue for subsequent liquefaction experiment. After the separation of the coal in the treatment of 50 °C lower vacuum drying 10h seal keeps after the. Coal direct liquefaction experiment in 450 °C and 3 mpa under hydrogen pressure conditions, with the crushing of the compared with the coal crushing, solvent after the heat treatment processing coal, its liquefied oil yield has been raised 12.9%, conversion and improves the 17.8%.