Pneumatic material delivery system with air flow limiting

Abstract

Apparatus for conveying granular material from a supply to receivers that retain and dispense the material when needed by process machine include a vacuum pump, an air flow limiter connected to the vacuum pump, a first conduit connecting the receivers to the air flow limiter, and a second conduit connecting the material supply to the receivers.

Description

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS[0001]This patent application is a 35 USC 120 division of co-pending U.S. Ser. No. 15 / 392,650, filed 28 Dec. 2016 in the names of Stephen B. Maguire and James Zinski, published 20 Apr. 2017 as US 2017 / 0107064 A1.[0002]The '650 patent application was a 35 USC 120 continuation-in-part of U.S. Ser. No. 14 / 574,561 entitled “Resin Delivery System with Air Flow Regulator” filed 18 Dec. 2014 in the name of Stephen B. Maguire, issued 28 Mar. 2017 as U.S. Pat. No. 9,604,793.[0003]The '650 patent application was also a 35 USC 120 continuation-in-part of U.S. Ser. No. 14 / 602,784 entitled “Method and Apparatus for Resin Delivery with Adjustable Air Flow Limiter” filed 22 Jan. 2015 in the name of Stephen B. Maguire, issued 24 Jan. 2017 as U.S. Pat. No. 9,550,636.[0004]The '650 patent application was yet also a 35 USC 120 continuation-in-part of co-pending U.S. Ser. No. 14 / 804,404 entitled “Vacuum Powered Resin Loading System Without Central Control” ...

AI Technical Summary

Benefits of technology

The invention is a better system for conveying pneumatic plastic resin pellets and other granular materials. It reduces costs while providing consistent control of air delivery to individual receivers. The system is also easy to expand as it grows. This is made possible by an air flow controller which limits the air pulled from each receiver to the correct predetermined flow rate, preventing excessive air flow and ensuring that air is only directed to the intended recipient.

Problems solved by technology

However, a larger pump may draw too much air with resulting damage to the material being conveyed.

While a larger pump could load several receivers at once, there is a risk that an “open” line, namely a line drawing only air, and no material, would cause the vacuum to drop too much, and no material would load.

Also, when only one receiver is loading material, air velocity might be too high, again with a risk of damaging the material.

With such an approach, the positive pressure results in movement of substantial amounts of air which may be used to carry the granular material.

Use of such high capacity vacuum pumps results in a rush of below atmospheric pressure air through the line, carrying the plastic resin pellets or other granular materials over a long distance.

Of course, the higher the number of receivers served by the system, the higher the cost.

If air flow is too slow, the pellets or other granules fall out of the air stream and rest on the bottom of the conduit, with resulting risk of clogging the conduit.

In such case, harder, more brittle plastic resin pellets and other granular materials may be damaged, resulting in dust within the conduit, which when drawn into the vacuum pump can damage the vacuum pump and render the system inoperative.

In the case of plastic resin pellets, this results in “angel hair”—long, wispy-thin strands of plastic film which eventually clog the conduit and cause the system to shut down.

However, a single twenty horsepower blower would result in far too high a conveying speed for the plastic resin pellets or other material granules through any reasonable size conduit.

Even with careful planning and design, results achieved by such pneumatic plastic resin pellet or other granular material conveying systems are not consistent.

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