Qilu Petrochemical: Paving a path for high-quality, high-value hydrogen production

Thread Content

“The outdoor pressure of the compressor is 3.2 MPa, which is normal. ”“Received, it is the same as the DCS instructions. ”On June 16, Luan Qingshun, the deputy shift leader of Shift 2 in the Hydrocarbon-Oil Combined Unit at Qilu Petrochemical’s refinery, was conducting inspections of the hydrogen production facility, communicating from time to time with the operators inside via walkie-talkie – this was their mandatory routine performed once per hour. “Refineries are major consumers of hydrogen. Over the past few years, we have been focused on reducing hydrogen costs by supplying low-cost raw materials to the hydrogenation units. ”Hu Donghu is the person in charge of the process operations in the plant’s production scheduling department. He started working at the refinery in 1982, which happened to be the year when the plant’s first hydrogen production unit was put into operation. Along the way, the relevant departments of the company and the refineries have continuously explored ways to optimize the production processes in light of market changes, thereby reducing the costs associated with hydrogen production and establishing a path for producing high-quality hydrogen at competitive prices. As refining capacity continues to increase and multiple hydrogenation units are built, there follows a shortage of hydrogen sources. In March 1982, a hydrogen production unit was established at this plant; it was designed to use the residue oil and naphtha from continuous reforming units as raw materials. However, the price of naphtha remained high, which in turn led to increased costs for hydrogen production. In 1991, the binary hydrogen plant was built and put into operation; although it increased hydrogen production, costs also rose simultaneously. How can hydrogen production costs be reduced while ensuring the quality of hydrogen? After thorough research and evaluation, the plant added two dry gas compressors to the hydrogen production unit in 2005; through the optimization of the feedstock process, it was finally possible to switch the hydrogen production feedstock from naphtha to natural gas. At that time, the price of natural gas was half that of naphtha, and partial success was achieved in reducing hydrogen production costs. In 2019, as a result of adjustments to the refining process and improvements in the raw materials used, the hydrogen consumption of the facilities decreased. This led to both of the refinery’s hydrogen production units as well as the coal-based hydrogen production unit at the second fertilizer plant operating at reduced capacity, putting the overall economic efficiency of the company’s hydrogen system under strain. The Company’s Production Management Department, in collaboration with the refinery and the Second Fertilizer Plant, set the goal of \"optimizing the operation of the hydrogen system by shutting down one hydrogen production unit.\" By optimizing the flow of materials, shutting down two hydrogen-consuming units in the refinery, and increasing the production of chemical by-product hydrogen at the second fertilizer plant, hydrogen production is made to act as a \"regulating valve,\" enabling the hydrogen pipeline network to be balanced by turning it on or off as needed. At the beginning of this year, the sudden outbreak of COVID-19 caused international crude oil prices to drop sharply, leading to a significant decline in the profitability of the group company’s refining division. Through overall optimization by the company, the refinery adopted a strategy of shutting down some units while keeping others operating at reduced capacity. Given that hydrogen production plants of type 1 consume a high amount of energy, the amount of hydrogen produced by such plants, together with the hydrogen generated as a by-product in continuous reforming units and the hydrogen available from external supply networks, is already sufficient to meet the entire plant’s hydrogen needs. On March 23, the “100-Day Effort to Improve Efficiency” campaign was launched; one hydrogen production unit was immediately shut down entirely, resulting in a significant reduction in the plant’s overall processing loss rate. “The raw materials for hydrogen production facilities mainly consist of coking dry gas, membrane off-gas, natural gas, or naphtha. The price of coking dry gas is relatively stable; we choose between natural gas and naphtha based on which one is cheaper. ”Sun Tao, the director of the hydrogen-oil combined workshop, has been researching for many years how to use existing plant processes to optimize the composition of hydrogen production raw materials, increase the yield of hydrogen, and reduce the costs associated with hydrogen production. In August 2016, they developed and put into use a combined process flow featuring membrane separation for concentration of methane hydrogen, hydrogen production, C3 production, and reforming PSA units, which increased the yield of hydrogen per ton of raw material by 0.27%. The plant found that using the tail oil produced by its continuous reforming unit as a raw material for hydrogen production was cheaper, at only one-third of the cost of natural gas. Seizing this opportunity, they promptly implemented a plan to switch from using gas to oil as the raw material for hydrogen production. “It is estimated that using stripping oil to produce hydrogen per ton can reduce costs by 3,100 yuan compared to using natural gas for hydrogen production. ”Guo Jianbao, the technical supervisor of the hydrogen-oil combined workshop, regards reducing hydrogen production costs as his own responsibility and monitors crude oil price changes on a daily basis. He is a veteran employee who switched from hydrogen production to the hydrogen-oil combined plant, and he is very familiar with the hydrogen production equipment. But converting gas to oil is easy to say, but extremely difficult to do. The process of producing hydrogen from crude oil was discontinued as early as 2010. After a decade of exposure to weather conditions, to put it back into use, it is necessary to systematically identify and address all potential problems one by one. Together with his colleagues, Guo Jianbao took advantage of the long May Day holiday to conduct a gas-tightness check on the crude oil feed line and the crude oil return line, addressing each issue that was identified; the process was successfully put into operation on May 6. “To maximize efficiency, process adjustments are made very frequently nowadays, requiring careful operation to ensure stable equipment operation. ”Luan Qingshun was at the scene like a sentinel on patrol. By the end of June, a total of 1,440 tons of hydrogen had been produced using decanting oil, generating significant economic benefits.