Wax Content Measuring Means

The system of the present invention relates to measuring systems in general and, more particularly, to measuring systems in a refinery unit.

Apparatus measures the wax content of waxy oil. The apparatus includes sensors sensing the gravity, the viscosity and the sulfur content of the waxy oil and providing corresponding signals. A circuit provides a signal corresponding to the wax content of the waxy oil in accordance with the sensed parameter signals.

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

The FIGURE shows a block diagram of a system, constructed in accordance with the present invention, for measuring the wax content of waxy oil.

The apparatus shown in the FIGURE determines the wax content by percent weight of wax in waxy oil flowing in a line 1. The wax content is determined in accordance with the following equation:

where C.sub.1 through C.sub.7 are constants and the preferred embodiment, when the temperature of the waxy oil being analyzed by a viscosity analyzer is substantially 210.degree.F, has values of 51.17, 4.3135, 182.83, 5.2388, 0.101, 6.6106 and 0.19609; W is the wax content in weight percent, A is the API gravity of the oil and V is the kinematic viscosity of the oil in centistokes.

A conventional type viscosity analyzer 3 samples the waxy oil in line 1 and provides a signal E.sub.1 to dividers 5, 6. Divider 5 divides a direct current voltage E.sub.A, corresponding to the constant C.sub.3, by signal E, to provide a signal corresponding to the term C.sub.3 1/V. Voltage E.sub.A is provided by a source of direct current voltages which is not shown for convenience. The direct current voltage source also provides direct current voltages E.sub.B through E.sub.G.

A conventional type gravity analyzer 8 samples the waxy oil in line 1 and provides a signal E.sub.2, corresponding to API gravity of the waxy oil in line 1, to divider 6 and to multipliers 9, 10 and 11. Divider 6 divides signal E.sub.2 by signal E.sub.1 to provide a signal, corresponding to the term A/V in the equation, to multiplier 7. Multiplier 7 multiplies the signal from divider 6 with voltage E.sub.B, which corresponds to the constant C.sub.6, to provide a signal corresponding to the term C.sub.6 A/V.

A sulfur analyzer 12, which may be of conventional type, samples the waxy oil in line 1 and provides signal E.sub.3 corresponding to the sulfur content of the waxy oil. Multiplier 9 multiplies signal E.sub.2 with signal E.sub.3 to provide a signal corresponding to the term AS in equation (1). A multiplier 15 multiplies the signal from multiplier 9 with voltage E.sub.C, corresponding to the term C.sub.7, to provide a signal corresponding to the term C.sub.7 [A][S]. Signal E.sub.2 is multiplied with voltage E.sub.D, corresponding to the term C.sub.2, by multiplier 10, to provide a signal corresponding to the term C.sub.2 A.

Multiplier 11 effectively squares the signal E.sub.2 and provides a corresponding signal to another multiplier 16 where it is multiplied with voltage E.sub.E corresponding to the term C.sub.5. Multiplier 16 provides a signal corresponding to the term C.sub.5 A.sup.2. A multiplier 18 multiplies signal E.sub.3 with voltage E.sub.F to provide a signal corresponding to the term C.sub.4 S.

All the positive terms in equation 1 are summed by summing means 20 and all the negative terms in equation 1 are summed by summing means 21. The sum signal provided by summing means 21 is then subtracted from the sum signal by subtracting means 24 to provide a signal E.sub.4, corresponding to the term W, which is recorded by recording means 26. Summing means 20 sums the signals from divider 5 and multipliers 15 and 16 with voltages E.sub.G to provide its sum signal. Summing means 21 sums the signals from multipliers 7, 10, 18 to provide its sum signal.

The system of the present invention as heretofore described determines the wax content of waxy oil and provides a record thereof. The system senses the viscosity, the API gravity and the sulfur content of the oil and utilizes the sensed parameters to determine the wax content.