Investigation of the co-processing technology of crude oil and coal and its deployment

The effect of process conditions on the co-processing technology of crude oil and coal was investigated. Crude oil/ coal matching performance, swelling degree, crude oil/coal slurry viscosity-temperature characteristics and process parameters were obtained via the laboratory scale and pilot scale studies. The optimum reaction temperature of the co-processing was 445~450 o C, the pressure was 19 MPa, the catalyst addition was 3 wt.%, the reaction time was 2 h, and the ratio of hydrogen to crude oil was 1500 (V/V). Furthermore, the co-processing technology including catalyst and corresponding equipment based on the slurry bed hydrogenation were developed. By using this co-processing technology, the feed ratio of crude oil and coal can be 1:1, the coal conversion rate can be over 99%, the light oil (oil and aromatics) yield was over 70%, and the end products were gasoline, diesel, jet fuel, aromatics and LPG. The product quality meets the Euro V standard, whilst aromatics accounted for 48% of the light oil. So it was proved to be feasible to co-re ﬁ ne crude oil and coal at a ratio of 1:1. What’s more, the slurry bed hydrogenation plant and its equipment were tested for long-term operation, and it has been proved that this co-processing technology could be deployed as large-scale industrial application.


INTRODUCTION
China is a large energy-demand country rich in coal and poor in oil.Most of the oil depends on imports.The shortage of oil resources and the deterioration of crude oil are becoming more and more serious, which brings many challenges to oil processing enterprises.In China, coal is burned as the main fuel, but the way and technology of energy utilization are backward, which will cause serious pollution to the environment.Therefore, it is crucial to realize the clean and effi cient utilization of coal energy by taking advantage of the Chinese energy structure 1-3 .
Direct coal liquefaction (DCL) is a way to achieve clean utilization of coal and has received a lot of attention since Bergius fi rst reported that coal could be turned into liquid by adding hydrogen 4, 5 .The successful operation of the world's fi rst and largest DCL plant in Erdos, Inner Mongolia, and constructed by the China Shenhua Energy Company Limited, has made China the only country mastering the core DCL technique for millions of tons of coal 6, 7 .DCL process is an essential technology to transform coal into oil or oil products by modifi cation of molecular structure and changing the proportions of hydrogen and carbon 8 .However, the separation and disposition of direct coal liquefaction residue (DCLR), which contains about 30-50 wt.% heavy liquid 9 , is still an intractable issue 10 .
The co-processing technology of crude oil and coal is a kind of DCL technology, and it's an important way to alleviate the current high dependence on petroleum resources 11, 12 .Using inferior heavy oil (including catalytic cracking slurry, atmospheric pressure residual oil, reduced pressure residual oil, DCC heavy oil, etc.) as solvent, part of coal is converted into liquid fuel by hydrocracking in the presence of hydrogen and catalyst.It has the advantages of low production cost, high conversion rate, wide adaptability of raw materials and good pro-duct quality, and can realize the coupling processing of coal and inferior heavy oil 13, 14 .In recent years, several domestic and foreign research institutions and companies have carried out technology research and development on catalysts, processes and core equipment for coal-oil co-processing, and formed (or are forming) their own technology systems 11, 15- 17 .
Both crude oil and coal are fossil fuels with similar molecular structure, containing a large proportion of polycyclic aromatic hydrocarbons, the only difference between them is that they are in different physical forms.Coal power swelled in the residue after crude oil distillation can react with the residue oil to produce light oil (distillate oil) via cracking and hydrogenation in the environment of hydrogen with high temperature and pressure.The residue oil and coal play different roles.The effects of the residue oil on coal are swelling, carrying and donating hydrogen, while coal acts as catalyst carrier and adsorbs coke.It should make sure the residue oil can be cracked, upgraded from heavy oil to light oil, also ensure it can provide hydrogen to coal, to promote the cracking of coal; meanwhile it should prevent the residue cracking to gases, therefore further study of the residue needs to be carried out to pick up the appreciate crude oil.
Therefore, to optimise crude oil and coal co-hydrogenation refi ning, the raw material must be studied in-depth to select the appropriate materials for the development of a highly effi cient and stable catalyst, and the effect of process conditions on the yield of oil be investigated.As the reaction conditions of the co-refi ning process are very harsh, the appropriate process must be chosen carefully in the pilot and industrial application stages.This work proposed a successful method of the slurry bed hydrogenation process application for the co-processing technology of crude oil and coal.Mixing catalytic cracking slurry, atmospheric pressure residual oil, reduced pressure residual oil, and raw coal as process Polish Journal of Chemical Technology, 24, 4, 39-50, 10.2478/pjct-2022-0027 raw materials, carrying out oil-coal co-refi ning research, investigating the reaction conversion effect and stability, and exploring the feasibility of different heavy oils as raw material oil mixed with coal in a 1:1 ratio for co--processing research.

Laboratory Scale Study
To select suitable raw materials by swelling test, hydrogen-donating test and coal applicability test to study the swelling capacity of oil to coal, oil hydrogen-donating ability and its cracking ability and coal suitability, respectively.
To study the viscosity-temperature properties of coal slurry (to determine coal oil slurry transporting conditions) via the carrying test.
To investigate reaction temperature, reaction pressure, catalyst dosage and reaction time on the gas yield, light oil (containing aromatics) yield and rate of coke and coal conversion via the experiment of process conditions testing.

Pilot Scale Study
To determine the process condition required of long period operation, assess the performance of the catalyst, understand optimal oil/coal ratio, coal conversion rate, product structure, light oil (containing aromatics) yield and properties and to check the coking of the device and the degree of wear.These factors may be analysed to determine suitability for long-term operations.

Raw Materials
Laboratory Scale Study 1. Swelling test: Daqing vacuum residue was used from Daqing Refi ning and Chemical Company (Heilongjiang province), atmospheric residue and vacuum residue were collected from Qilu Petrochemical Company (Shengli) (Zibo City, Shandong Province), vacuum residue from Tahe Petrochemical Company (Tahe, Akesu Region of Xinjiang Autonomous Region), and Hami bituminous coal (Hami area of Xinjiang Uygur Autonomous Region).
2. Hydrogen-donating test: In addition to the raw material mentioned above, Shengli catalytic slurry and deoiled asphalt from the Qilu Petrochemical Industries Co (Zibo City, Shandong Province) were used.
3. Coal applicability test: Shengli atmospheric residue and vacuum residue were used as the raw oil, while bituminous coal (Ordos, Inner Mongolia Autonomous Region) and sub-bituminous coal (Jakarta, Indonesia) were used as the raw coal.
4. Carrying test: Atmospheric residue was used from Shengli, coal power and wax were from Hami.
5. Process conditions test: Atmospheric residue was used from Shengli and bituminous coal was used from Hami.
Particle size has a signifi cant impact on slurryability of coal slurry and coal hydrogenation performance.Moisture and ash content should be controlled at a relatively low level; water content was reduced to less than 4 wt% 18 , and ash content was down to less than 5 wt%.Considering the energy consumption of raw coal processing, the dry basis ash of coal was 15 wt%, whilst moisture in the air dried basis was less than 25 wt%, and the Hastelloy wear index was greater than 50.As this experiment mainly studied the effect of volatile matter of pulverized coal, the coal particle size, moisture and ash content control were controlled at the same level.The properties of raw oil and coal are shown in Tables 1 and 2.

Pilot Scale Study
Crude oil from Shengli oil-fi eld, Shandong Province of China and bituminous coal from Hami, Xinjiang China were chosen as raw materials, and their properties are shown in Tables 2 and 3.

Catalyst
Thermal cracking and hydrogenation were the main reactions of this co-processing technology, it was also associated with desulphurisation, denitrifi cation, metal removal, thus the catalyst should have the ability to reduce coal macromolecular bridge bond cleavage energy, promote coal macromolecule thermal cracking and transfer activated hydrogen 19 .
The hydrogenation of the mixture of residue oil and coal used slurry bed hydrocracking technology, catalyst was eventually brought out with coke that was diffi cult to recycle, so the cost needs to be considered carefully.The process we developed using a nano-scale iron-based composite catalyst, its main components were ferric oxide (FeOOH), the auxiliary was ammonium molybdate, and the carrier was pulverized coal with high ratio surface area, high catalytic activity with low cost which was less Table 1.Main properties of oil than 200 μm.The catalyst was pre-dispersed prior to entering the reaction system, which can greatly improve the dispersion of this catalyst.The special pore structure of pulverized coal can take the coke condensed out of the system, avoiding any potential coking and blocking.
2. Hydrogen-donating test: test equipment was the intermittent stirred autoclave reactor, the volume was 0.5 L, the main specifi cations: effective volume was 0.5 L; design pressure was 30 Mpa; design temperature was 550 o C; temperature control accuracy was ±1 o C. The apparatus was provided with a controllable rate of stirring paddle to ensure that the reaction process of gas liquid solid three-phase can have good mass transfer contact to promote the reaction.The reactor adopted electric heating, automatic temperature control and recording, two temperature measuring points were arranged in the wall, which can make sure good temperature control.A reactor is equipped with pressure sensors to measure the pressure inside the reactor.The cable extractor was the main analysis equipment (YYSXT-06, the Shanghai extension equipment Co., Ltd.).
3. Applicability test of coal: the test and analysis equipment were as used for the hydrogen-donating test.
4. Carrying test: in addition to the hydrogen-donating test equipment, a viscometer, (Thermo Scientifi c Haake VT-550) was used.
5. Process conditions test: the hydrogen-donating test equipment was used.

Pilot Scale Study
The main testing equipment for the pilot study was slurry bed and fi xed bed hydrogenation for crude oil distillation and catalytic reforming.The slurry bed hydrocracking device was the core of the pilot test.The fi xed bed hydrogenation and catalyst reforming used the distillate oil from the slurry bed apparatus, which was non-continuous.

Laboratory Scale Study
1. Swelling test: the volumetric method followed for determination of coal swelling ratio Q consisted of packing 5 g dry pulverized coal into the centrifuge tubes, centrifuged at 50 r/min for 3 minutes resulting in a tube of coal sample height H1.Oil residue 5 g was added to the tube and stirred all the coal particles were wetted; the tube was permitted to stand for a period of time before repeating the centrifuge step, resulting in a tube of coal sample height H2.The press type was calculated using the swelling degree 20 .The swelling ratio Q = H2/H1 was calculated for the Daqing VR, the Shengli residue, and the reduction of Tahe slag.
2. Hydrogen-donating test: coal from Hami was reacted with six different oils (see Table 1) respectively in the autoclave.The products were divided into gaseous, liquid and solid phases.Chemical composition and volume fraction for the gaseous phase products were determined by gas chromatography (GC).Liquid and solid products were extracted and separated by hexane and tetrahydrofuran, and the extraction oil yield and conversion rate were calculated.This process route is shown in Figure 1.

Table 3. The properties of Chinese Shengli crude oil
Table 2. Main properties of coal 3. Coal applicability test: coal from Ordos and sub--bituminous coal from Indonesia and the atmospheric residue from Shengli were selected for co-refi nement to investigate the infl uence of coal properties on its applicability.The coal applicability was evaluated via the coal conversion rate, gas yield and oil yield.The process route used was identical to the hydrogen-donating test.
4. Carrying test: the effects of temperature on the viscosity of coal/oil slurry for different ratios of coal and residue oil were carried out to determine the infl uence of viscosity of coal/oil slurry on its liquidity.
5. Process conditions test: combining the test results above, reaction temperature and pressure, the amount of catalyst and the effect of reaction time were studied through the autoclave test.In these tests, the reaction pressure referred to the initial hydrogen pressure.The conversion rate of coal, gas and oil yield were characterized.

Pilot Scale Study
1.The Shengli crude oil was distilled into two parts: light fraction (less than 310 o C) and heavy fraction (greater than 310 o C).The heavy fraction was mixed with pulverized coal, catalyst and auxiliary in the coal slurry tank, then they were pre-heated and compressed by pumping into the pre-heater.The pre-heated raw materials were fed into the reactor for hydrogenation reaction (the hydrogen to the mixture of crude oil and coal ratio is 1 000-1500/1), then the reacted material entered the high temperature solid-liquid separator.The mixture was separated into a gas phase (as high oil), and the gas phase fed into the low temperature separator where it was further separated into gas, water and light oil (as low oil).A portion of the gas used for circulation, a part of the vent, high oil through the solid-liquid separation device to get rid of the residue after oil, oil by distillation device further divided into <370 o C fraction (as head oil) and 370 o C~500 o C fraction (as VGO).A fl ow chart of slurry reactor is shown in Figure 2.
Low oil, head oil and light fraction in the fi xed bed hydrogenation unit were from full fraction hydrogenation refi ning, naphtha and diesel fractions.
2. Directly distillate oil in the diesel fraction and slurry bed diesel fraction were mixed according to a proportion by prolifi c naphtha catalyst for fi xed bed hydrogenation cracking, naphtha, aviation kerosene and diesel.
3. Aromatics and gasoline production were obtained according to the aromatic potential content of naphtha.

Swelling Test
The swelling effect of Daqing, Shengli, Shengli and Tahe residue on coal was studied to determine the main factors affecting swelling and mild swelling time.The results are shown in Figure 3   rate of coal at 97.25%, oil yield at 88.37%, gas yield of 12.31%.While Shengli and Tahe vacuum residue, catalytic oil slurry were the worst.This shows that the hydrogen donation capacity of coal was the strongest in the crude oil of the intermediate base and the cyclic alkyl crude oil, and the residue was the second; the catalytic oil slurry, the residue and the residue of the paraffi n base were the weakest.had an optimum temperature of swelling and swelling time of 240 o C and 140 minutes, with a degree of swelling of 1.038.Shengli atmospheric residue and vacuum residue had an optimum swelling temperature and time of 220 o C and 120 minutes; the degree of swelling was 1.145 and 1.153 respectively.Tahe vacuum residue had an optimal swelling temperature and swelling time of 220 o C and 100 minutes, reaching a degree of swelling of 1.162.From the experimental results, it was determined that the order of swelling effi cacy was, from most to least potent, Tahe, Shengli, and fi nally Daqing residue.
The residue of the three types of crude oils, Daqing, Shengli and Tahe (paraffi n base, intermediate base and napthenic crude, respectively) contained diminishing quantities of aromatics, resin and asphaltene.As the residue and coal molecular structure were similar to that of aromatic hydrocarbon, their resin and asphaltene content was higher, and the residue of coal molecular fl owing phase affi nity was stronger, hence they were easier to weaken or destroy the coal molecular weak bond, and the molecular coal became loose with coal volume increases.Therefore, in terms of swelling, crude oil and coal was suitable for co-refi ning integration for ring alkyl or intermediate base crude oil.

Hydrogenation reaction Test
Table 4 shows the reaction conditions of hydrogenation reaction (named reactions 1-6 respectively), and the reaction results are shown in Table 5.It can be concluded that the Shengli atmospheric residue (AR) and coal with hydrogen donation were the best, with conversion  The results show that the hydrogen donation process at high temperature and pressure followed the free radical reaction mechanism.The main reaction was fast pyrolysis of coal under high temperature, generation of asphaltenes, preasphaltene and other molecules; these molecules and molecules of residue hydrogenation reaction were important.Asphaltene and preasphaltene macromolecular hydrogenation to activation of hydrogen atoms can be higher, if activation of hydrogen atoms from the hydrogen molecule could not be satisfi ed, this part of the activated hydrogen must come from residue.So residue to be activated hydrogen atoms from the hydrogen, the hydrogen atom molecules are stimulated for the activation of the hydrogen atom, the hydrogen atom to activation FCH asphaltene and higher preasphaltene and coal molecular hydrogen.The hydrogenation cracking was to promote its small molecule hydrogen donating ability of large molecules, two hydrogens, slag oil in the continuous hydrogenation and hydrogen donor in the process of achieving its cracking, become light oil molecules.The residue should be able to transfer the activation of hydrogen, but also to achieve its own cracking in this process.The hydrogen donation process is shown in Figure 4. Oil molecular hydrogen donors to asphaltene, preasphaltene and coal molecules must meet the following three conditions: accepting from the activation of molecular hydrogen, hydrogen atoms in the reaction conditions can be induced by activation of hydrogen atoms, and hydrogen molecules have a similar electron cloud structure, and with this condition is cycloalkanes and the ring number less than 3 of the aromatic ring.These conditions were satisfi ed by the Shengli AR and VR reduction, followed by a large number of Tahe vacuum residue; while hydrocarbon containing Daqing residue did not have hydrogen donor ability, but was susceptible to cracking, so oil and gas yield was very high as well; oil asphalt had a large number of polycyclic aromatic hydrocarbons.Its hydrogen donation ability was weak, and itself was not easy to crack, hence oil and gas yield and coal conversion rate were relatively low.

Applicability Test of Coal
To investigate the applicability of coal used for co-refining, the Ordos coal and an Indonesian sub-bituminous coal and Shengli atmospheric residue were selected (reactions 7 and 8), the reaction conditions are shown in Table 4, and the results are shown in Table 5.The reaction results showed that the conversion rate of Hami bituminous, and oil and gas yield was the highest, and it is the most suitable raw material for co-processing.
The molecular structure of coal consists of a fused ring of aromatic hydrocarbons -aromatic nucleus -as the basic unit, a key bridge link in the formation of cross-linked three-dimensional network structure, which macromolecular network structure for the stationary phase, small molecules trapped in the stationary and mobile phases.With the improvement of the degree of coalifi cation, the structure unit ring condensation number increased, side chains, and the number of functional groups, bridge bond decreased 21 , the diffi culty of the cracking increased, adaptability of refi ning decreased.Table 2 shows that the Hami Coal atomic H/C ratio and volatility score highest, with degree of coalifi cation minimum.Therefore, Hami Coal is the most suitable for use in common raw material refi ning, followed by Indonesia sub-bituminous coal, and Ordos coal being the least suitable.
It can be concluded that the H/C atomic ratio and volatile of coal for crude oil and coal integration of refi ning would be appropriate values.Considering the energy consumption of raw coal treatment, coal dry basis ash would be less than 15 wt%, moisture in the air-dried basis would be less than 25 wt%, Hastelloy wear index would be greater than 50.

Carrying Test
To determine the infl uence of coal oil slurry viscosity liquidity, the effects of the impact of temperature on the viscosity in different coal ratios are shown in Figure 5.
With the increase of the proportion of coal in the coal oil slurry, the slurry viscosity also increased.With the increase of temperature, the coal oil slurry viscosity decreased gradually, after a certain temperature the viscosity reduction rate slowed down.Residue and coal quality as 50/50 than the confi gured into coal slurry in optimum swelling temperature was 220 o C under the condition of dynamic viscosity as high as 548 mPa • s.Regarding transportation, when the proportion of coal and oil residue was 55/45 and 60/40 the dynamic viscosity was 426 and 349 mPa • s respectively, which was not conducive to delivery.As the residue in the material ratio is too high, it will reduce the economic advantage of the technology, and wax oil can signifi cantly reduce the viscosity of coal slurry.So consider in coal slurry to join is refi ning reaction generated 360~500 o C VGO fraction, when the ratio of the residue/pulverized coal/wax was The viscosity of the coal slurry with respect to temperature varied: when the temperature exceeded 220 o C the viscosity decreased slowly; the higher the proportion of coal, the lower the viscosity.When the proportion of coal was higher than 50/50 the increase in the viscosity and temperature dependency were less obvious; thus test results showed that the oil/gas ratio should not be less than 50/50.Shengli residue oil (greater than 310 o C), Hami coal and oil to the quality than the confi gured into coal oil slurry, the coal oil slurry system of dynamic viscosity decreases rapidly with increasing temperature.When the temperature reached 90 o C, the dynamic viscosity decreased to 240 mPa • s, with good fl uidity.

Process Condition
The process conditions were according to the above experimental results, with Shengli AR and Hami Coal as raw material, coal oil slurry in accordance with the mass ratio of residue/pulverized coal/ VGO was 40/40/20.As the main infl uence factors of coal conversion and oil gas yield are reaction temperature, reaction pressure, catalyst dosage and reaction time, the four aspects were studied respectively.
1. Reaction temperature test parameters were initial hydrogen pressure of 10 MPa, catalyst dosage of 3 wt%, reaction time of 2 h.The effect of reaction temperature on the refi ning reaction was investigated, and results are shown in Figure 6(a): coal conversion rate increases with temperature, after 450 o C it reached a maximum of 97.25%, then began to decrease.The gas yield increased with the temperature; light oil (distillate oil) yield increased with temperature, at 450 o C yield reached a maximum of 88.37%, then began to decrease.
The relationship of temperature ranges to coal decomposition has been reported 22 .Total chain reaction including coal thermal cracking reaction, cracking products and residue of hydrogenation reaction, with the increase of temperature, coal macromolecular structure depolymerization, decomposition and hydrogenation reaction and increased the rate of conversion of coal, when the optimum ranges of temperature rise, coal conversion and oil yield reached the highest value, temperature and decomposition reaction than hydrogen reaction, condensation reaction increased and the oil yield decreased 23 and reaction of the crude oil molecules also is so.According to the thermodynamic analysis, the pyrolysis reaction is endothermic reaction, hence the increase of coal conversion rate and the yield of pyrolysis gas the temperature increased.Analysis from the perspective of dynamics, the reaction temperature and accelerated the cracking, hydrogenation reaction and condensation reaction rate, conversion rate, so the coal gas and oil yield were increased with the increase of temperature.The effect of reaction temperature on hydrogenation reaction and condensation reaction differs: in the low--temperature range, the temperature of acceleration plays a major role in hydrogen reaction, and when it reaches a certain degree, reaction temperature continues to rise, the condensation reaction of dominant macromolecules cracking free radical fragments has undergone rapid con-densation, partial oil condensation for coke, direct the performance of coal conversion and oil yield decreased, therefore, according to the test results.The appropriate reaction temperature is 450 o C.
2. Reaction pressure was analysed with a temperature of 450 o C, catalyst dosage of 3 wt.%,and reaction time of 2 h.The effect of initial hydrogen pressure on the refi ning reaction was investigated, the results are shown in Figure 6(b).Coal conversion rate and light oil (distillate oil) yield increased with temperature.When the initial hydrogen pressure reaches 10 MPa (corresponding to the reaction pressure as 19 MPa) for coal conversion of 97.25%, light oil (distillate oil) yield of up to 88.37%, and after the increase slowed down, the gas yield in reach maximum as 88.37% for 10 MPa, and then begins to decrease.
Coal molecular thermal cracking products and oil molecules reacting with hydrogen occurring in the initial stage is aromatics saturation reaction, decreasing the number of molecules.Increasing the pressure favours the reaction when it is controlled by kinetics, so the oil yield and gas yield are increased with pressure.When the initial hydrogen pressure reaches 10 MPa, the branched aromatic molecules rupture, the aromatic hydrocarbons decompose and increase the number of molecules involved in the reaction.As the reaction is started by thermodynamic control, the oil yield in pressure exceeds 10 MPa, the increase is slow, the gas recovery rate began to decline.Therefore, according to the test results the optimum initial hydrogen pressure is 10 MPa.
3. Effect of catalyst dosage was analysed with a reaction temperature of 450 o C, initial hydrogen pressure of 10 MPa, and reaction time of 2 h.The results are shown in Figure 6(c).Coal conversion, oil yield and gas yield -respectively 97.25%, 88.37% and 12.31% -increased with the amount of catalyst used, up to 3 wt.%.
Catalyst reduced macromolecular fracture, hydrogen molecules in the hydrogen reaction and the activation of hydrogen atom and residue transfer active hydrogen and asphaltene, preasphaltene and coal molecular accept activation the activation energy of hydrogen, in the catalyst from 1wt% increase to 3 wt%, the overall activation energy of the reaction system decreased a lot, performance for coal conversion and oil and gas yield increase obviously, but as a catalyst for a given reaction system activation energy is reduced is limited so in the catalyst addition to reducing the activation energy is increased after, the catalytic effect is not apparent.Therefore, the optimum catalyst addition was 3 wt.%.
4. The reaction time was analysed with a reaction temperature of 450 o C, catalyst dosage of 3 wt.%,and an initial hydrogen pressure of 10 MPa.The results are shown in Figure 6(d): coal conversion and gas yield increased with the reaction time.Light oil (distillate oil) yield peaked at 88.37% with the reaction time at 2 h, after which it began to decrease.
The reason for that is in reaction to 2 h that big molecules generated light oil molecular reaction under thermodynamic control slow progress, and light oil molecules at high temperature cracking into smaller molecules, so the coal conversion rate and gas yield increased gradually, and the oil yield began to decrease.Therefore, the optimal reaction time was 2 h.

Pilot Scale Study
Pilot scale data for crude oil and coal provide a basis for determining residue properties not only refl ect the properties of crude oil, but also refl ect the condition of crude oil distillation.When the crude oil distillation temperature was too low, of the residue light group in refi ning reaction light group splitting into a gas, and reduces the yield of oil.When the distillation temperature was too high, and the residual oil viscosity was higher, so the hydrogen donating ability would fall.Therefore, according to the temperature of the crude oil distillation residue, the hydrogen donor and swelling tests may be used to determine the carriage.For a crude oil distillation temperature of 310 o C the atmospheric residue oil quantity was 83.09%; the properties are given in Table 6 whilst the main operating conditions of slurry bed studies are found in Table 7.
Due to the limitation of the equipment, the temperature of the coal slurry entering the feed pump should not exceed 90 o C. The feed pump dynamic viscosity was up to 350 mPa • s.The corresponding oil coal slurry ratio for atmospheric residue/ pulverized coal/ wax was 40/40/20, as shown in Figure 7. Based on the results of swelling tests with the temperature of coal oil slurry at 220 o C swelling effect was optimised when the ratio for coal oil slurry of atmospheric residue/pulverized coal/wax was 40/40/20, with a dynamic viscosity of 186 mPa • s.The optimal conditions for conveying are when the ratio of coal oil slurry atmospheric residue/ pulverized coal/wax was 83/100/17, with slurry viscosity of 337 mPa • s.In practice, it would be recommended to use this temperature to maximize the proportion of pulverized coal and atmospheric residue, the main benefi t being minimisation of the cost of raw materials.
For the test focusing on the effect of reaction temperature and pressure the reaction results are shown in Tables 8-12.When the reaction temperature was 445 o C the coal conversion rate was as high as 99.75%.Liquid products (including water) yield 79.05%, distillate yield reached 71.75% (less than 500 o C), of which fraction oil yield (less than 370 o C) was 48.61% and the diesel fraction yield was 37.86%.Hydrogen consumption was only 3.01%.By increasing the temperature to 450 o C the coal conversion rate decreased slightly to 98.46%; liquid product (including water) yield increased to 82.36%, fraction oil less than 500 o C yield reached 75.11%, in which fraction oil less than 370 o C yield increased 6.57%.The result was improved production of diesel oil and wax oil, whilst the yield of coal and coke yield decreased by 3.21% and 2.94%.Water and gas yield did not change.However, hydrogen consumption increased by 0.34%, and the utilization ratio of hydrogen could be further improved.
It was found when the reaction pressure was raised from 19 MPa to 20 MPa the oil yield increased very little.As boosting pressure incurs a direct cost, the best reaction pressure was 19 MPa.Under the conditions of this experiment, the pilot plant was run continuously for 1000 h; inspection of the reactor and high-temperature separator found no signs of coking or wear phenomenon.
The reaction temperature was reached 445 o C, it would accelerate the asphaltene coke formation, through the laboratory test method refl ected the conversion of coal decreased; but it was also conducive to cracking of asphaltene, the light oil (distillate oil) yield increased, so it can be to predict the optimum reaction temperature was 455 o C, distillate yield more than 78%.However, the reaction temperature was too high to accelerate the coking and visible reaction temperature can effectively increase the yield of liquid oil (oil & aromatics).Considering that the hydrocracking reaction process involves polycondensation the reaction temperature should not be exceeded 456 o C.   The fraction of oil produced processed following the procedure in section 3.6.2;the products obtained were gasoline, aviation kerosene, diesel, aromatics, liquefi ed gas and coal tar.The yield of light oil product (distillate oil) obtained was 71.6%, the gas yield was 12.5%, the coke yield was 18%, and the hydrogen consumption was 6.5%.Whilst the yield of the slurry bed device for light oil (distillate oil) was up to 78%, the total yield of the fi nal light oil products (pr oil and aromatics) was 74% once the part of the light oil (distillate oil) was processed through a fi xed bed with hydrogen and catalytic reforming unit.When the ratio of feed crude oil and coal was 1:1 and the ratio of the residue and coal into the slurry bed was 0.85:1, the yield of slurry bed light oil (distillate oil) was 77%, the total yield of the fi nal light oil products (oil and aromatics) was 70.24%.Gasoline, aviation kerosene, diesel oil and aromatics accounted for 18%, 15%, 19% and 48% in the light oil products (oil and aromatics), respectively.The quality index of the gasoline, aviation kerosene and diesel are listed in Tables 13-15.This device was operated several times, each time running for 1000 h.It was found that the static equipment, pumps, valves, pipes and pipe fi ttings had no obvious coking or signs of wear after test completion.

INDUSTRIAL APPLICATIONS
According to the process of co-refi ning crude oil and coal described in this study above, the production scale of each standard module in the modular model plant could be 5 million tons/year.

Selection and Proportioning of Raw Materials
The experiment proved that the refi ning process is suitable for crude oil, intermediate base or naphthenic crude oil, heavy oil or coal tar; coal to bituminous coal or lignite, coal dry basis ash less than 15 wt.%, moisture in the air dried basis less than 25 wt%, Hastelloy can wear index greater than 50.Volatile matter and hydrogen carbon directly affect the light oil yield, refi ning technology for volatile greater than 37%, the H/C atomic ratio greater than 0.75.
After the distillation of crude oil atmospheric residue and coal powder is mixed into the slurry bed hydrocracking device, coal in the proportion of the material is mainly affected by the residue hydrogen donating abilities and carrying effect reduce viscosity of coal slurry and enhanced oil hydrogen donating abilities by using wax, the proportion of oil and coal was 1/1.

Process Flow
The whole process is shown in Figure 8, which used the Shengli crude oil and Hami coal refi ning process as an example.

Product Structure and Quality
In the refi ning process for ultra clean gasoline, aviation kerosene and diesel, aromatic hydrocarbons and liquefi ed petroleum gas (LPG), no fuel oil, heavy diesel oil, such as low-quality oil, the yield of light oil (oil and aromatics) products could be over 70%.The ratio of aromatics in oil (oil & aromatics) can be 48%.The oil quality is not less than that shown in Tables 6-8.

Major Installations and Core Equipment
Machinery processes required for the co-refi ning process include distillation, grinding coal, mixing, hydrogen production, slurry bed hydrogenation, fi xed bed hydrogenation, catalytic reforming, light hydrocarbon recovery and sulphur recovery.The core equipment includes making coal obtain depth swelling of multistage intensively mixed kneading machine, belt circulation structure of the slurry bed reactor, multistage separation system, can greatly reduce valve wear grade pressure reducing system and can switch is fl exible use of multiple hearth structure of vacuum furnace.

Technology Maturity
The core equipment and devices have been used successfully in China to complete a pilot study to identify and optimise the selection of raw materials, and process conditions including catalyst.

CONCLUSIONS
The main conclusions of this study were as follows.Swelling test, hydrogen-donating test and coal applicability test were carried out to study a combination of candidate oils and coals.The crude oil and coal co--processing was developed via laboratory and pilot scale studies.The crude oil suitable for co-refi ning process is intermediate base or naphthenic crude oil, heavy oil or coal tar.While the coal is bituminous coal or lignite.Volatile matter and hydrogen carbon directly affect the light oil yield, co-processing technology for volatile greater than 37%, the H/C atomic ratio greater than 0.75.Besides, the reaction temperature was 445~450 o C, the pressure was 19 MPa, the catalyst addition was 3 wt.%, the reaction time was 2 h, and the ratio of hydrogen to crude oil was 1500 (V/V).It was also found to be feasible to co-refi ne crude oil and coal at a ratio of 1:1.
The structure and quality of products were determined and the quality of oil was higher than Euro-V standard.Combining coal direct liquefaction projects in China, with the experience in the long period operation of coal oil slurry bed hydrogenation unit, it was demonstrated that the proposed technology tends to be mature for large-scale deployment.

Figure 2 .
Figure 2. Schematic diagram of slurry bed hydrogenation process in plot scale

Figure 3 .
Figure 3.The effect of Swelling time on Swelling degree

Figure 6 .
Figure 6.The effect of reaction conditions on the reaction results

Figure 7 .
Figure 7. Property of Viscosity-temperature of oil-coal slurry

Table 4 .
Reaction conditions of hydrogenation reaction test

Table 5 .
Reaction results of hydrogenation reaction test

Table 7 .
Pilot scale reaction conditions

Table 6 .
The properties of Shengli residue

Table 9 .
The properties of the fraction less than 170 o C

Table 8 .
The slurry bed hydrocracking reaction results

Table 14 .
Main quality indexes of aviation kerosene

Table 13 .
Main quality indexes of gasoline

Table 12 .
The properties of Shengli residue