Characterization Factor Monitor

The present invention relates to monitors in general and, more particularly, to a monitor for providing a signal corresponding to a characteristic of an oil.

A monitor samples oil and provides a signal corresponding to the characterization factor of the oil. The monitor includes a refractometer and a flash point analyzer which samples the oil and provides signals corresponding to the refractive index and the Cleveland open cup flash point temperature in degrees F of the oil. A sensor provides a signal corresponding to the sensed temperature of the oil. A network provides signal K in accordance with the signals from the refractometer, the flash point analyzer and the temperature sensor.

The objects and advantages of the invention will appear more fully hereinafter from a consideration of the detailed description which follows, taken together with the accompanying drawings wherein one embodiment of the invention is illustrated by way of example. It is to be expressly understood, however, that the drawings are for illustration purposes only and are not to be construed as defining the limits of the invention.

FIG. 1 is a simplified block diagram of a monitor constructed in accordance with the present invention for sampling oil and providing a signal corresponding to the characterization factor of the oil.

FIG. 2 is a detailed block diagram of the comparing means shown in FIG. 1.

The characterization factor, often referred to as the Watson K, is a useful, empirical tool for expressing by a single number the approximate relative paraffinicity of a petroleum fraction.

The magnitude of K provides a useful information about an oil fraction, including an indication of the type of crude from which a virgin oil was derived, or the type of processing that a refined oil may have received. The technical literature also includes descriptions of ways to use the Watson K factor to interrelate various physical properties of oils, including boil point temperature, molecular weight, hydrogen content and specific heat.

Therefore, it is extremely useful to continuously monitor the characterization factor of refinery processed streams of distinguish among products, and to detect changes that occur during processing. The characterization factor K can also be used as the basis for controlling various refinery operations.

Heretofore, the physical properties that have been used for estimating the Watson K factor of a particular oil fraction have mainly included the density, or specific gravity, in combination with viscosity, average boiling point, flash point or aniline point. It has now been discovered unexpectedly that the Watson K factor can be accurately determined from a combination of two properties not previously used together, namely, the flash point temperature and the refractive index.

Referring to FIG. 1, oil flowing in a pipe 1 also flows through bypass pipes 3 and 4 as hereinafter explained, to return to the stream of oil in pipe 1. A temperature sensor 8 senses oil in line 3 and provides a signal T corresponding thereto. A conventional type flash point analyzer 12 samples the oil in line 3 and provides the sample oil to line 4. Analyzer 12 provides a signal F corresponding to the flash point temperature of the oil. A refractometer 15 also samples the oil and provides a signal RIt corresponding to the refractive index at temperature T of the sample oil. The sample oil from the refractometer 15 is also returned to line 4. Signals T, F and RIt are provided to comparing means 20 receiving temperature reference signals, flash point temperature reference signals and refractive index reference signals. Comparing means 20, through a comparison of signal T with the temperature reference signals, of signal F with the F reference signals and of signal RIt with the RIt reference signals, provides address signals S1 through S5 to memory means 30. Memory means 30 has stored within it different values for K for different combinations of F, T and RIt which have been determined from laboratory testing or other conventional methods. Signals S1 through S5 address memory means 30 and cause it to provide signal K corresponding to the Watson K factor of the oil flowing through pipe 1.

Referring now to FIG. 2, temperature reference signals are provided to multiplexing switches 50 in a comparing network 55. Multiplexing switches are controlled by control signals provided by control signal means 57 in response to signals from counter means 60. Counter means 60 counts passed pulses from an AND gate 63 receiving clock pulses from a clock 66. Counter means 60 is also reset by a reset pulse from reset means 68 as hereinafter explained.

Signal T is provided to a comparator 70 which compares signal T with a multiplexed reference signal from multiplexing switches 50 and provides a comparison signal to an inverter 73 and to an AND gate 75. Inverter 73 provides its output to AND gate 63 to control the passage of clock pulses from clock 66 as hereinafter explained.

In operation, a comparison signal from comparator 70 is initially at a low logic level which is inverted to a high logic level signal by inverter 73 to enable AND gate 63 to pass the clock pulses from clock 66. As counter means 60 counts the passed clock pulses, its signals are decoded by control signal means 57 to provide control signals causing multiplexing switches 50 to sequentially pass the temperature reference signals to comparator 70. At some point in time, a multiplex temperature reference signal is greater than signal T which causes comparators 70 to provide the comparison signal at a high logic level which after inversion by inverter 73 disables AND gate 63 to prevent further counting by counter means 60. The reference signal from multiplexing switches 50 at this time represents the value of signal T and is provided to an analog-to-digital converter 80.

Similarly, signal RIt and RIt reference signals are provided to comparing network 55A. Elements having the same numerical designation but with an alpha suffix are constructed and operate in a similar manner as the element having the same numeric identification without a suffix. Comparing network 55A, when it has selected the correct RIt reference signal, provides the selected RIt reference signal to another analog-to-digital converter 80A and the comparison signal to AND gate 75.

Similarly, comparing network 55B processes signal T and T reference signals to provide a selected T reference signal to yet another analog-to-digital converter 80B and its comparison signal to AND gate 75. When all three parameter reference signals have been selected, the comparison signals from comparing networks 55, 55A and 55B are at high logic levels causing AND gate 75 to provide its output at a high logic level which, in turn, is inverted by an inverter 82 and provided to analog-to-digital converters 80, 80A and 80B. The changing of logic levels, from a high logic level to a low logic level, of the signal from inverter 82 causes analog-to-digital converters 80, 80A and 80B to convert the selected reference signals and provide corresponding digital signals S1 through S6.

The testing cycle is reinitiated by reset means 68 providing a reset pulse which resets the counter means 60 in each of the comparing networks 55, 55A and 55B, causing them to recycle. Reset means 68 may be just simply a manually operative switch receiving a voltage which, when activated, provides a reset pulse. It may be an automatic feature that is a counter receiving clock pulses from clock 66 and after a predetermined time interval automatically provides a reset pulse.

The present invention as hereinbefore stated is a monitor which provides a signal corresponding to the Watson K characterization factor of oil being monitored.