Hydrorefining

Hydrorefining generally refers to the reprocessing of some petroleum products that cannot meet the requirements of use through a hydrogenation process to make them meet the specified performance indicators.

Refined feedstock:

Gasoline, diesel oil, kerosene, lubricating oil, petroleum wax, etc. containing more harmful impurities such as sulfur, oxygen and nitrogen.

Refined products:

Refined and modified gasoline, diesel oil, kerosene, lubricating oil, petroleum wax and other products.

Basic concepts

Hydrorefining process is a general term for the catalytic upgrading of various oils under hydrogen pressure. It refers to the hydrogenolysis reaction of various non-hydrocarbon compounds in oil products under the conditions of certain temperature and pressure in the presence of catalyst and hydrogen, and then removed from oil products to achieve the purpose of refining oil products.

Hydrorefining is mainly used for the refining of oil products, and its main purpose is to improve the performance of oil products through refining.

Production process

The process flow of hydrorefining generally includes three parts: reaction system, generated oil heat exchange, cooling, separation system and circulating hydrogen system.

①　Reaction system

The raw material oil is mixed with new hydrogen and circulating hydrogen, and after heat exchange with the reaction product, it enters the heating furnace in a gas-liquid mixed state (this method is called hydrogen mixing in front of the furnace), and is heated to the reaction temperature and enters the reactor.

The reactor feed can be either gas phase (when refining gasoline) or gas-liquid miscible phase (when refining diesel or oils heavier than diesel). The catalyst in the reactor is generally packed in layers to facilitate the injection of cold hydrogen to control the reaction temperature. The circulating hydrogen and the oil mixture are passed through each stage of the catalyst bed for hydrogenation.

②　Generate oil heat exchange, cooling and separation system

The reaction product comes out from the bottom of the reactor and enters the high pressure separator after heat exchange and cooling.

Before the cooler, high-pressure washing water is injected into the product to dissolve the ammonia and part of the hydrogen sulfide produced by the reaction.

The reaction product is separated from oil and gas in a high-pressure separator, and the separated gas is circulating hydrogen, in which in addition to the main component hydrogen, there are a small amount of gaseous hydrocarbons (non-condensable gas) and hydrogen sulfide insoluble in water; the separated liquid The product is a hydrogenated oil in which a small amount of gaseous hydrocarbons and hydrogen sulfide are also dissolved;

The generated oil is decompressed and then enters the low-pressure separator to further separate components such as gaseous hydrocarbons, and the products are separated into qualified products by de-fractionation system.

③　Circulating hydrogen system

After the circulating hydrogen separated from the high-pressure separator passes through the storage tank and the circulating hydrogen compressor, a small part (about 30%) directly enters the reactor as cold hydrogen, and most of the remaining part is sent to be mixed with the raw material oil and recycled in the device. In order to ensure the purity of circulating hydrogen and avoid the accumulation of hydrogen sulfide in the system, a hydrogen sulfide recovery system is commonly used. Generally, ethanolamine is used to absorb and remove hydrogen sulfide, and the rich liquid (absorption liquid) is regenerated and recycled. The desorbed hydrogen sulfide is sent to the sulfur production unit to recover the sulfur, and the purified hydrogen is recycled.

Production equipment

a. Heating furnace

The raw material oil is mixed with new hydrogen and circulating hydrogen, and after heat exchange with the reaction product, it enters the heating furnace in a gas-liquid mixed phase and is heated to the reaction temperature and enters the reactor.

b. Reactor

Heat exchange and hydrogen mixing after the furnace enters the reactor.

In the reaction in the catalyst bed of the reactor, sulfur, oxygen, nitrogen and metal compounds are easily removed (by hydrogenation into hydrogen sulfide, water, ammonia, etc.), and olefins are saturated at the same time.

c. High pressure and low pressure separator

The hydrogenated oil enters the high pressure and low pressure separators in turn after heat exchange and water cooling.

d. Stripper

The hydrogenated oil from the low pressure separator exchanges heat with the stripped hydrogenated oil, and enters the heating furnace for heating, and then enters the stripping tower, whose function is to strip off the gas and light fractions remaining in the oil. .