REFINERY

Of course, some processes do not require a reactor, e.g., some oil refinery processes. Here, the design starts with the sepauration system and moves outward to the heat exchanger network and utilities. However, the basic hierarchy prevails. 

Figure 2.8 shows the essential features of a refinery catalytic cracker. This particular reaction is accompanied hy the deposition of carhon on the surface of the catalyst. The fiuidized-hed reactor allows the catalyst to he withdrawn continuously and circulated to a fiuidized regenerator, where the carhon is burnt ofi" in an air stream, allowing regenerated catalyst to he returned to the cracker. 

Figure 2.8 A fluidized-bed reactor allows the catalyst to be continuously withdrawn and regenerated as with the refinery catalytic cracker.

Along the same lines, a distillation can be simulated by gas phase chromatography. As in a refinery, distillation in the laboratory is very often the first step to be carried out, because it gives the yields in different cuts gasoline, kerosene, etc., and makes further characterization of the cuts possible. 

It is clear that these gases have widely varying compositions according to the processes used, but refinery gas is distinguished from natural gases by the presence of hydrogen, mono- and diolefins, and even acetylenes. 

In Appendix 1, the reader will find the data required to calculate the properties of the most common hydrocarbons as well as those components that most frequently accompany them in refinery process streams. The data are grouped in seven categories ( ... 

The average error of this simplified method is about 3°C and can reach 5°C. Table 4.22 shows an application of this method calculating the temperature of hydrate formation of a refinery gas at 14 bar. Table 4.23 gives an example applied to natural gas at 80 bar. Note that the presence of H2S increases the hydrate formation temperature. 

We believe to have shown here that the RVP of gasoline is a primary characteristic for quality resulting from a delicate compromise between the demands for vehicle performance, optimization of refinery operations and environmental protection. 

Table 5.10 gives octane number examples for some conventional refinery stocks. These are given as orders of magnitude because the properties can vary according to process severity and the specified distillation range. 

Octane numbers (RON and MON) of some conventional refinery streams (orders of magnitude). 

Low temperature characteristics of a diesei fuei affect more its fuel feed system than its behavior when burning. However, we will examine them here because of their strong impact on refinery flow schemes. 

Table 5.15 gives some physical-chemical characteristics of selected main refinery streams capable of being added to the diesel fuel pool. Also shown is the weight per cent yield corresponding to each stock, that is, the quantity of product obtained from the feedstock. 

The results given here are on a laboratory basis. During formulation in the refinery, the cold characteristics are much less satisfactory with a penalty of around for cases where it is desired to keep the same yield from the crude oil. 

Their production in a refinery begins with base stocks having narrow boiling ranges and high octane numbers iso C5 cuts (used in small concentrations because of their high volatility) or alkylates are sought for such formulations. 

This category comprises conventional LPG (commercial propane and butane), home-heating oil and heavy fuels. All these materials are used to produce thermal energy in equipment whose size varies widely from small heaters or gas stoves to refinery furnaces. Without describing the requirements in detail for each combustion system, we will give the main specifications for each of the different petroleum fuels. 

Typical characteristics of some refinery stocks used in the production of heavy fuels. 

Leaving the refinery, jet fuel has generally no free water and contains only a small quantity of dissolved water. But humidity from the air and tank breathing result in continuous intrusion of water that must be then removed by decanting and filtration. This is why jet fuel needs to be tested for its ability to separate the contained water. 

All modern refineries have conversion units, designed to transform black effluent streams into lighter products gas, gasoline, diesel fuel. Among these conversion units, coking processes take place by pyrolysis and push the cracking reaction so far that the residue from the operation is very heavy it is called coke . 

The measurement of a crude oil s viscosity at different temperatures is particularly important for the calculation of pressure drop in pipelines and refinery piping systems, as well as for the specification of pumps and exchangers. 

During storage, sediments decant with the water phase and deposit along with paraffins and asphalts in the bottoms of storage tanks as thick sludges or slurries (BS W). The interface between the water-sediment and the crude must be well monitored in order to avoid pumping the slurry into the refinery s operating units where it can cause serious upsets. 

The measurement of chlorides is standardized (NF M 07-023, ASTM 3230) the result of two measurements is expressed in mg of NaCl/kg of crude. Table 8.14 gives the contents of some crude oils these values come from measurements taken in a refinery and thereby include the salts brought in by contamination. 

In the refinery the salts deposit in the tubes of exchangers and reduce heat transfer, while in heater tubes, hot spots are created favoring coke formation. 

It is possible to calculate the properties of wider cuts given the characteristics of the smaller fractions when these properties are additive in volume, weight or moles. Only the specific gravity, vapor pressure, sulfur content, and aromatics content give this advantage. All others, such as viscosity, flash point, pour point, need to be measured. In this case it is preferable to proceed with a TBP distillation of the wider cuts that correspond with those in an actual refinery whose properties have been measured. 

This type of study, applied over all the cuts, enables the refinery flow scheme to be defined in order to satisfy a given set of market conditions starting from one or more crude oil feedstocks. 

A refinery lubricant base stock is obtained having an viscosity index around 100, certain hydrotreatments result in Vi s of 130, and paraffin hydroisomerization provides oils with a VI close to 150. 

Early 1970 s simple refinery (motor fuels, heavy fuels)... 

For the long term, 2010-2020 refinery complex meeting environmental reg 4)atimn and ensuring total conversion of the heavy ends... 

Environmental Protection Processes that treat the refinery gases (fuel and tail gas), stack gas, and water effluents. 

Figure 10.2 shows the locations of reforming and isomerization units in refinery configurations. 

Residue (slurry) or clarified oil (CLO) used as refinery fuel or as a base in the manufacture of carbon black. 

Feedstocks are natural gas, refinery fuel gas, LPG and paraffinic naphthas. After elimination of CO2, the last traces of contaminants are converted to methane (methanation) or eliminated by adsorption on molecular sieves (PSA process). 

Figure 10.14 gives the position of this process in the refinery flowscheme. 

Hydrogen sulfide concentrates in refinery off gases. Before being used as fuel gas, the gas undergoes an amine (MEA, DEA, etc.) washing step in order to extract the H2S. 

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