Method for accurately measuring real-time dew-point value and total moisture content of a material

• US 10,613,046 B2
• Filed: 02/21/2016
• Issued: 04/07/2020
• Est. Priority Date: 02/23/2015
• Status: Active Grant

• Current Assignee: Machinesense LLC
• Original Assignee: Machinesense LLC
• Inventors: Pal, Biplab
• Primary Examiner(s): Gray, David M.
• Assistant Examiner(s): Evans, Geoffrey T
• Application Number:
  US15/049,098
• Publication Number:
  US 20160245765A1
• Time in Patent Office: 1,507 Days
• Field of Search: None
• CPC Class Codes: B29B 13/065 of powder or pellets
• CPC Class Codes: B29B 9/16 Auxiliary treatment of granules
• CPC Class Codes: F26B 2200/08 Granular materials
• CPC Class Codes: F26B 25/22 Controlling the drying process in dependence on liquid content of solid materials or objects
• CPC Class Codes: F26B 3/06 the gas or vapour flowing through the materials or objects to be dried F26B3/14 takes precedence
• CPC Class Codes: F26B 9/063 for drying granular material in bulk, e.g. grain bins or silos with false floor shallow layer rotary sweep drying bins F26B9/10; perforated wall silos with drying air channels in the stack F26B9/103
• CPC Class Codes: G01N 25/66 by investigating dew-point

Abstract

A system and method for accurately measuring the real-time valid dew-point value of a material and determining the total moisture content of the material within the valid dew-point value by using an algorithm during the material drying process. The algorithm estimates the valid dew-point value of the material and the total moisture content of the material by analyzing the sensor data received on a server. The algorithm determines a valid dew-point value by estimating an inflection point for the material, and the total moisture content of the material is determined within the valid dew-point value.

Claims

1. A method for measuring real-time dew-point value of a resin and determining total moisture content of said resin in the course of drying said resin preparatory to molding or extruding said resin into finished plastic parts comprising:

a) acquiring data from temperature and dew-point sensors positioned at a sole drying air outlet of a hopper having said resin therein;

b) transmitting the acquired data, using programmable logic controller (PLC), relay, or wireless sensor networks, to a server;

c) estimating initial moisture content of said resin before the drying process begins;

d) continuously estimating moisture content of said resin during the drying process, by executing a second algorithm on the server;

e) measuring a valid dew-point by determining at the server an inflection point of the continuously estimated moisture content for said resin; and

f) determining the total moisture content of said material after determining said inflection point by executing a third algorithm on the server.

2. The method as claimed in claim 1, wherein said method estimates the initial moisture content of said resin by executing on the server this algorithm where k is an experience-based V(0)=(k/Mp)∫

₀^∞

DP(t′

)*D_Air(t′

)*F(t′

)dt′

correction factor, D_air is the measured initial density of air, MP is the total mass of material in the hopper, “

DP”

is initial dew-point of air in the hopper, and “

t”

is time using the acquired data.

3. Ancillary to a dryer having a hopper for hot air drying of granular resin material preparatory to molding or extrusion, a system for measuring real-time dew-point of V(t)=V(0)−

(k/Mp)∫

₀^tDP(t′

)*D_Air(t′

)*F(t′

)dt′

granular polymeric resin material to be molded or extruded into finished plastic products once the polymeric resin material is sufficiently dry, and determining total moisture content of said polymeric resin material comprising;

a) a server;

b) a temperature sensor for sensing temperature of drying air exiting the hopper;

c) a dew-point sensor for sensing dew point of drying air entering the hopper;

d) a communication system using a programmable logic controller, a relay, or a wireless network for providing data from the sensors to the server;

e) the server comprising an analyzer module for

i) estimating initial moisture content of said polymeric resin material by using an algorithm before the drying process begins;

ii) estimating moisture content of said polymeric resin material at any instant of time during the drying process by using said algorithm;

iii) measuring dew-point of said polymeric resin material by determining an inflection point of moisture content for said polymeric resin material as a function of time using a second algorithm; and

iv) determining total moisture content of said polymeric resin material after determining said inflection point by using second algorithm.

4. The system of claim 3, wherein said system estimates the initial moisture content of said polymeric resin material by executing on the server a set of equations using the acquired data.

5. A method for continuously estimating moisture content of a resin and determining total moisture content of said resin in the course of drying said resin preparatory to molding or extruding said resin into finished plastic parts comprising:

a) acquiring data from temperature and dew-point sensors positioned at a sole drying air outlet of a drying hopper having said resin therein;

b) transmitting the acquired data, using a programmable logic controller (PLC), a relay, or a wireless sensor network, to a server;

c) estimating initial moisture content of said resin before the drying process begins by executing in the server, this algorithm V(0)=(k/Mp)∫

₀^∞

DP(t′

)*D_Air(t′

)*F(t′

)dt′

where k is an experience-based correction factor, D_air is the measured initial density of air, MP is the total mass of material in the hopper, “

DP”

is initial dew-point of air in the hopper, and “

t”

is time;

d) continuously estimating moisture content of said resin during the drying process by executing the algorithm V(t)=V(0)−

(k/Mp)∫

₀^tDP(t′

)*D_Air(t′

)*F(t′

)dt′

when the values are as noted above in limitation “

c”

;

e) determining the total moisture content of said material;

i) using the algorithm U(t)=k∫

₀^tDP(t′

)*D_Air(t′

)*F(t′

)dt′

to determine the mass of water vapor that has been forced from the resin;

ii) measuring the weight of resin remaining in the hopper; and

iii) dividing the measured weight of resin by the water vapor mass found in step (c) minus the water vapor forced from the resin as found in subsection (i) of step “

e”

.

6. The method of claim 5 further comprising determining a valid dew point for the resin by:

a) measuring a valid dew-point through determining an inflection point for said Resin by differentiating the algorithm of limitation “

d”

of claim 5; and

b) determining the total moisture content of said material remaining in the hopper after determining said inflection point by;

i) weighing the resin in the hopper;

ii) using the algorithm U(t)=k∫

₀^tDP(t′

)*D_Air(t′

)*F(t′

)dt′

to determine the mass of water vapor that has been forced from the resin;

iii) measuring the weight of resin remaining in the hopper; and

iv) dividing the measured weight of resin remaining in the hopper by the water vapor mass that has been forced from the resin.