Landfill gas treatment method with polishing

• US 9,580,369 B2
• Filed: 04/22/2016
• Issued: 02/28/2017
• Est. Priority Date: 09/02/2011
• Status: Active Grant

• Current Assignee: David C. Morrow, Luke N. Morrow, Paul D. Morrow
• Original Assignee: David C. Morrow, Luke N. Morrow, Paul D. Morrow
• Inventors: Morrow, David C., Morrow, Paul D., Morrow, Luke N.
• Primary Examiner(s): Smith, Duane
• Assistant Examiner(s): SHAO, PHILLIP Y
• Application Number:
  US15/135,885
• Publication Number:
  US 20160237007A1
• Time in Patent Office: 312 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: B01D 19/0036 Flash degasification the other groups take precedence
• CPC Class Codes: B01D 2252/2025 Ethers or esters of alkylene glycols, e.g. ethylene or propylene carbonate
• CPC Class Codes: B01D 2252/2026 Polyethylene glycol, ethers or esters thereof, e.g. Selexol
• CPC Class Codes: B01D 2256/245 Methane
• CPC Class Codes: B01D 2257/304 Hydrogen sulfide
• CPC Class Codes: B01D 2257/504 Carbon dioxide
• CPC Class Codes: B01D 2257/7022 Aliphatic hydrocarbons
• CPC Class Codes: B01D 2257/7027 Aromatic hydrocarbons
• CPC Class Codes: B01D 2257/80 Water
• CPC Class Codes: B01D 2258/05 Biogas
• CPC Class Codes: B01D 53/14 by absorption
• CPC Class Codes: B01D 53/1406 Multiple stage absorption
• CPC Class Codes: B01D 53/1425 Regeneration of liquid absorbents
• CPC Class Codes: B01D 53/1475 Removing carbon dioxide
• CPC Class Codes: C07C 7/11 by absorption, i.e. purification or separation of gaseous hydrocarbons with the aid of liquids
• CPC Class Codes: C10L 3/104 Carbon dioxide
• CPC Class Codes: Y02C 20/20 of methane
• CPC Class Codes: Y02C 20/40 of CO2
• CPC Class Codes: Y02E 50/30 Fuel from waste, e.g. synthetic alcohol or diesel

Abstract

A method for recovering methane gas from a landfill involves the use of a main absorber, a flash system, an optional ancillary absorber and an optional polishing absorber. The recovered gas is maintained at a temperature that enhances a solvent'"'"'s ability to absorb carbon dioxide from the recovered gas. While the main absorber uses the solvent for absorbing most of the carbon dioxide from the recovered gas, the flash system removes much of the carbon dioxide from the solvent exiting the main absorber. In some examples, at least portion of the flash system operates at subatmospheric pressure to create a vacuum that draws in a generally inert stripper gas (e.g., air, nitrogen, etc.) at atmospheric pressure. The stripper gas helps remove carbon dioxide from the solvent in the flash system.

Claims

1. A method for using a solvent in treating a gas from a landfill, wherein the gas and the solvent have a varying concentration of carbon dioxide, the method comprising:

conveying the gas through a main absorber;

conveying substantially all of the gas from the main absorber through a polishing absorber;

conveying at a main mass flow rate a main current of solvent through the main absorber, thereby exposing the gas to the main current of solvent;

the main current of solvent extracting carbon dioxide from the gas;

conveying at a polishing mass flow rate a polishing current of solvent through the polishing absorber, thereby exposing the gas to the polishing current of solvent;

the polishing current of solvent extracting additional carbon dioxide from the gas,

the main mass flow rate through the main absorber being at least three times greater than the polishing mass flow rate in the polishing absorber;

housing the main absorber and the polishing absorber within a common outer shell;

the main absorber and the polishing absorber defining an area of transition therebetween; and

at the area of transition, the polishing current of solvent joining and becoming part of the main current of solvent.

2. The method of claim 1, further comprising:

conveying an ancillary current of solvent through an ancillary absorber;

the ancillary current of solvent flowing from the ancillary absorber to the polishing absorber;

the ancillary current of solvent flowing from the ancillary absorber becoming the polishing current of solvent flowing through the polishing absorber;

conveying a current of air through the ancillary absorber, thereby exposing the ancillary current of solvent to the current of air; and

the current of air extracting carbon dioxide from the ancillary current of solvent flowing through the ancillary absorber.

3. The method of claim 1, further comprising:

conveying an ancillary current of solvent through an ancillary absorber;

the ancillary current of solvent flowing from the ancillary absorber to the polishing absorber;

the ancillary current of solvent flowing from the ancillary absorber becoming the polishing current of solvent flowing through the polishing absorber;

conveying a current of nitrogen through the ancillary absorber, thereby exposing the ancillary current of solvent to the current of nitrogen; and

the current of nitrogen extracting carbon dioxide from the ancillary current of solvent flowing through the ancillary absorber.

4. The method of claim 1, further comprising after the polishing current of solvent extracting additional carbon dioxide from the gas, adding propane to the gas.