Low pressure continuous dense phase convey system using a non-critical air control system

• US 8,747,029 B2
• Filed: 05/02/2011
• Issued: 06/10/2014
• Est. Priority Date: 05/03/2010
• Status: Active Grant

• Current Assignee: Schenck Process LLC (Schenck Process Holding GmbH)
• Original Assignee: MAC Equipment, Inc. (Schenck Process Holding GmbH)
• Inventors: Thorn, Jonathan
• Primary Examiner(s): DILLON JR, JOSEPH A
• Application Number:
  US13/099,123
• Publication Number:
  US 20110268510A1
• Time in Patent Office: 1,135 Days
• Field of Search: 406/30, 406/127, 406/144, 406/197
• US Class Current: 406/197
• CPC Class Codes: B65G 53/66 Use of indicator or control devices, e.g. for controlling gas pressure, for controlling proportions of material and gas, for indicating or preventing jamming of material controlling the flow of coal firing systems C21B5/003
• CPC Class Codes: G05D 7/0688 by combined action on throttling means and flow sources G05D7/0694 takes precedence

Abstract

An air control system for a low pressure continuous dense phase convey system employs a non-critical air flow control system that allows for a supply pressure to be only incrementally larger than a convey pressure. The convey system has an inlet for introduction of pressurized air into the system and an airlock associated with a feedpoint for introduction of particulate into the system. A first pressure sensor is positioned immediately downstream of an air source to measure the supply pressure, and a second pressure transducer is positioned proximate an airlock to measure the convey pressure. The non-critical air flow control system is dependent on the supply and convey pressures and a position of a control valve, such as a sonic nozzle. The difference between the convey pressure and the supply pressure is less than 10% of the supply pressure.

Claims

1. A method of conveying particulate through a convey system employing a non-critical air flow control system, the method comprising the steps of:

positioning an air source upstream of an inlet of the convey system;

positioning a control valve downstream of the air source and immediately upstream of the inlet;

positioning a first pressure transducer downstream of the air source and upstream of the control valve for sensing of a supply pressure produced by the air source;

positioning a second pressure transducer proximate a feedpoint of particulate into the convey system for sensing a convey pressure of the convey system;

employing a controller having a processor and a memory to receive first and second signals respectively representing the first and second sensed pressure signals; and

employing the controller to process the first and second pressure signals and to control a position of the control valve to obtain a desired rate of air flow according to the following equation;

2. The method of claim 1, wherein a ratio of the supply pressure P1 to the convey pressure P2 is less than 1.25:

1, such that the rate of air flow through the control valve is non-critical.

3. The method of claim 2, wherein a ratio of the supply pressure P1 to the convey pressure P2 is less than 1.1:

1.

4. The method of claim 2, wherein the supply pressure P1 varies during the conveying operation by less than ±

1%, and the supply pressure P1 is not held constant.

5. The method of claim 2, wherein a difference in the convey pressure P2 and the supply pressure P1 is 1-2 psi.

6. The method of claim 1, wherein the rate of air flow is determined based on a desired convey velocity for the particulate, a size of the convey line, and a calculated air leakage through the airlock.