Application of active promoter in the heavy oil catalytic unit to increase the heavy oil at the bottom of the converter cracking tower

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The use of active promoters in the heavy oil at the bottom of the converter cracking tower in heavy oil catalytic units. The application of such promoters in heavy oil catalytic units: These units were first built in 1988 with a design capacity of 150,000 tons per year; in 1995, their capacity was increased to 500,000 tons per year. The raw material intended for processing was Dagang atmospheric residue. However, due to a disruption in the supply of this raw material, the units stopped operating. Subsequently, the main raw materials used were imported M-100 fuel oil along with purchased atmospheric residue. As the quality of these raw materials became increasingly poor, this led to excessive coking during reactions, a decline in the units’ processing capacity, an increase in catalyst consumption, and high levels of slurry discharge. The production figures for 2005 are shown in Table-1. Table 1: Production data for 2005
| Parameter | Value |
|-----------|-------|
| Daily refining capacity (T) | 1020.72 |
| Light liquid yield (%) | 74.89 |
| Liquefied gas yield (%) | 15.8 |
| Slurry yield (%) | 7.51 |
| Catalyst consumption per T | 1.56 kg |

As can be seen from Table 1, the processing volume in 2005 was less than 340,000 tons, with a catalyst consumption of 1.56 kg per T – this does not include the additional 200+ tons of catalysts purchased from external suppliers. For these reasons, the Production Technology Department and the Catalyst Plant conducted thorough investigations and technical discussions before deciding to test the use of an activating catalyst produced by Engelhard Company for cracking the heavy oil at the bottom of the converter. The main physical and chemical properties of this catalyst are shown in Table 2, along with those of the main catalyst used in this facility (RAG-9). Table 2 – Main physical and chemical properties of Converter additives and RAG-9 main catalyst
Property | Converter | RAG-9 |
AI2O3 | 38% | 45% |
Na2O | 0.25% | 0.25% |
Specific surface area | ≥380 m2/g | ≥220 m2/g |
Bulk density | 0.70 g/ml | 0.72 g/ml |
Average particle size | 75 | 71.2 |
Sieve analysis (0–40 mesh) | 12% | 18% |
According to communications with Engelhard Company and available data, its key characteristics include a unique DMS matrix that provides active pores for the diffusion of heavy oil molecules, enabling selective cracking ； Very high activity, which can reduce catalyst consumption ； Significant bottom oil cracking capacity, which can reduce the slurry yield ； High specific surface area, nearly twice that of ordinary catalysts ； Can be used with any catalyst ； Medium bed ratio, suitable for fluidization in all types of units ； Increase the processing volume and the amount of heavy oil blended, while keeping the yields of coke and dry gas constant or with only a slight increase ； High wear resistance ； Good resistance to heavy metal pollution ； Increase the diffusion rate of oil and gas molecules within the catalyst pores ； Used in combination with propylene production enhancers to increase the propylene content in liquefied gas ； Addition amount: Only 5-15% of the system’s storage is required ； Since the amount added can be increased or decreased at any time, the device operation plan can be adjusted quickly. On January 26, 2006, experiments were initiated to increase the addition of active catalysts to the heavy oil at the bottom of the Converter cracking tower. These experiments lasted for four weeks, during which approximately nine tons of Converter catalysts were added. The experiments were carried out in two phases. 1. Rapid addition phase: During the first eight days, 500 kilograms of Converter catalyst were added per day, for a total of four tons (added in four batches). In the second week, and during the first five days of the third week, 330 kilograms of Converter catalyst were added per day (distributed over two shifts), with additions continuing for 20 days in total; approximately 9 tons of Converter catalyst were added this way. The total capacity of catalysts in this facility is around 100 tons. Calculated on a proportionate basis with the catalyst, the amount of additive in this case accounts for about 7% to 8% of the main catalyst. 2. Stable supplementation phase: From two days after the third week following addition to the fourth week, depending on the operational conditions and the properties of the catalyst, 140–165 kilograms of Converter catalyst aid are added per day (in two doses, in the morning and afternoon). Following the instructions of the relevant leaders at the branch company, Production Technology Department 1 and the Catalysis Plant jointly set the objectives for this experiment aimed at increasing the activity of the catalyst used in the bottom oil of the Converter cracking tower: to rapidly boost the activity of the catalyst present in the system without adding any catalyst, and ultimately without having to remove any catalyst at all, thereby reducing catalyst consumption and saving on processing costs ； Increase the plant’s processing capacity or the amount of slag added, while keeping the yields of coke and dry gas constant, in order to raise the total liquid yield ； Used in combination with propylene production enhancers, it increases the liquefied gas yield while raising the propylene content in the liquefied gas ； On the condition that the solid content of the slurry is within acceptable limits, gradually reduce the amount of slurry discharged. The analysis statistics of the raw materials two weeks before the experiment and during the experiment are shown in Table-3 below. Table 3 – Analysis of raw materials before and during the experiment: Before addition, After addition. Dates: 1.13, 1.24, 2.7, 2.21. Density: 0.9177, 0.9286, 0.9163, 0.9227. Residual carbon: 5.99, 5.72, 6.26, 5.56. Distillate at 500°C: 54, 52, 59, 52. In Table 3, the analysis of raw materials on January 13 and January 24 was conducted before the experiment, while the analysis was carried out on February 7 and February 21 during experiments using the Converter catalyst. It can be seen from these analyses that there are minimal differences in the density, residual carbon, and distillate at 500°C of the raw materials before and after the experiment; therefore, it can be concluded that the properties of the raw materials remained essentially unchanged before and after the experiment. After adding the Converter catalyst on January 26th, the control values of various process operation parameters remained essentially the same before and after the experiment. The catalyst consumption per week before and after the addition of the Converter catalyst is shown in Table-4. Table-4 Catalyst consumption before and after addition. Date, Amount of catalyst added, T, Catalyst consumption in kg/T: Before addition: 05–12.30: -1.5, 11.27: 1.46; 1.6–1.12: 11.15: 1.49; 1.13–1.19: 10.13: 1.42; 1.20–1.26: 10.98: 1.52. After addition: 1.27–2.2: 9.66: 1.29; 2.3–2.9: 9.85: 1.27; 2.10–2.16: 6.9: 0.92; 2.17–2.23: 6.92: 0.92. The equilibrium catalyst activity in the system before and after the experiment with the Converter catalyst promoter is shown in Table-5. Table-5: Catalyst activity before and after addition
Date | Equilibrium catalyst activity (%)
Before addition: 1.14, 54.2; 1.19, 60.1; 1.25, 59.8
After addition: 2.6, 61.2; 2.9, 68.2; 2.15, 71.1; 2.20, 63.7

As can be seen from Tables-4 and Table-5, the Converter catalyst produced by American Anger Company used in this experiment led to a gradual increase in the equilibrium catalyst activity within the system after it was added. During the period of steady addition, the catalyst activity increased by about five percentage points. Meanwhile, the consumption of the main catalyst decreased gradually, by approximately 0.4 kilograms per ton compared to before the experiment. Assuming a consumption of 0.12 kilograms per ton for the Converter catalyst during the steady addition period, and with a cost of 23 yuan per kilogram for the catalyst, the savings amount to 9.2 yuan per ton due to this reduction in consumption. The cost of the Converter catalyst is 58 yuan per kilogram, with a consumption of 0.12 kilograms per ton; thus, the cost associated with it is 6.96 yuan. By subtracting the cost of this catalyst from the savings resulting from the use of less primary catalyst, an amount of 2.24 yuan can be saved per ton of raw material processed. Assuming a processing volume of 1,050 tons per day, this translates to savings of 2,352 yuan per day. The material balance of the unit before and after adding the Converter catalyst is shown in Table-6. Table-6 Material Balance
Date | Processing Volume (T) | Light Liquid Yield (%) | Liquefied Gas Yield (%) | Slurry Yield (%)
Before Addition: 05--12.30 –1.5 7821 75.95 16.09 6.84
06--1.6 –1.12 7454 75.11 16.31 7.31
1.13–1.19 7154 74.67 15.32 7.53
1.20–1.26 7240 74.96 15.71 7.46
After Addition: 1.27–2.2 7447 74.77 17.03 6.9
2.3–2.9 7777 74.87 16.45 6.67
2.10–2.16 7487 74.84 16.15 7.19
2.17–2.23 7497 77.5 18.03 6.42
Based on production statistics over the four weeks before and after the addition of the Converter catalyst, the processing volume increased by 539 tons after addition, with an average daily increase of 25.66 tons. The yield of light liquids increased by 0.33%, while the yield of liquefied gas increased by 1.06%. The yield of slurry, on the other hand, decreased by 0.5%. This includes a power fluctuation to the equipment on February 13, which caused the smoke extractor to stop operating and led to a 40-minute interruption in feed supply; the air compressor stopped working for 3 hours. The situation would have been better if those periods were excluded. According to statistics, compared with the first four weeks without the Converter catalyst, the propylene content (W) in liquefied gas increased by about 1.9% after adding the catalyst for four weeks. The Converter promoter test met the expected objectives to a large extent, yielding good economic benefits. After the completion of this test, the amount of promoter added and the parameters during the stable supplementation phase remained relatively constant. Based on operational data such as the level of recycled liquid, reaction temperature, and catalyst analysis, minor adjustments were made to the amount of Converter promoter added. The production data for February to July 2006 are shown in Table-7. Table 7: Production data from February to July 2006
| Parameter | Value |
|-------------------------|--------------------|
| Daily processing volume | 1159.42 T |
| Light liquid yield | 77.99% |
| Liquefied gas yield | 18.94% |
| Slurry yield | 6.30% |
| Catalyst consumption per T | 0.91 kg/T |

Comparing Table 1 and Table 7, it can be seen that with the addition of the Converter catalyst, the daily processing volume increased by 138.7 tons, the light liquid yield rose by 3.1%, the catalyst consumption per ton decreased by 0.65 kg/T, the slurry yield dropped by 1.21%, while the liquefied gas yield increased by 3.14% (this is partly due to the improvements made to the feed nozzles in the riser; more details will be provided in another article). Despite a decrease in catalyst consumption of 0.65 kg/T, the catalyst’s activity remained unchanged and even increased slightly, while its selectivity improved. This is the effect of the Converter catalyst. From February to July 2006, the catalyst consumption was 0.14 kg/T; at a cost of 58,000 yuan per ton, the cost of using this catalyst for producing one ton of oil was 8.12 yuan. With the addition of the Converter catalyst, the catalyst consumption per ton decreased by 0.65 kg/T. At a cost of 23,000 yuan per ton for the catalyst, this resulted in a savings of 14.95 yuan per ton. In total, this meant that 6.83 yuan could be saved per ton of oil processed. From February to July 2006, a total of 183,188 tons of raw material were processed; without taking into account any increase in the yield of oil production, the catalyst costs were saved by approximately 1.25 million yuan during that period. Due to the improved selectivity and increased activity of the catalyst, the yield of liquefied gas rose steadily as oil production increased, with the propylene content in the liquefied gas remaining at 43–45% (by weight), thereby providing sufficient raw material for the downstream facilities of the branch company. The Converter promoter has a significant effect on promoting the catalytic cracking of heavy oil and increasing the conversion rate of the desired products. It helps to rapidly enhance the activity and selectivity of the catalysts in the system; simultaneously, without increasing the yields of dry gas and coke, the yields of light liquids and liquefied gas increase significantly. When used in combination with promoters for increasing propylene production, the propylene content in the liquefied gas is about two percentage points higher than when using the propylene-promoting agent alone ； The Converter catalyst promoter is added using the existing small feeding system, allowing for great flexibility in adjusting the amount added, which can be modified as needed based on operational requirements. Through the joint efforts of the First Production Technology Department and the Catalysis Plant of our branch company, the pilot test using the Converter catalyst was a **success**, achieving the desired objectives and yielding significant economic benefits, thus contributing to the healthy development of our branch company.