A system and method of regenerating a pre-purification vessel is provided that is particularly suitable for pre-purification of a feed air stream in cryogenic air separation unit that uses an oxygen-enriched purge gas stream for regeneration of the pre-purification unit. The disclosed pre-purification systems and methods are configured to remove substantially all of the water, carbon dioxide and other impurities from a feed air stream, optionally including hydrogen and carbon monoxide impurities. The method of regenerating a pre-purification vessel preferably involves regenerating the pre-purification vessel with an oxygen-enriched purge gas after depressurization of the vessel and thereafter partially repressurizing the pre-purification vessel with an auxiliary purge gas thereby diluting the oxygen concentration of the gases contained in the pre-purification vessel and optionally depressurizing the partially repressurized vessel.

This specification relates to operating industrial facilities, for example, crude oil refining facilities or other industrial facilities that include operating plants that process natural gas or recover natural gas liquids.

A system for the removal of nitrogen from a liquid natural gas (LNG) stream. The system. comprises a feed heat changer and a stripper column. The heat receives the LNG stream and cools the LNG stream via heat exchange with a stripper column side-draw stream to yield a cooled LNG stream and a heated side-draw stream. The stripper column receives the cooled LNG stream at a first tray and the heated side-draw stream. The stripper column produces the stripper column side-draw stream, a stripper column overhead stream, and a stripper column bottom stream. The stripper column side-draw stream is taken from the stripper column at a second tray. The second tray is at least about 15 feet higher than the feed heat exchanger.

Implementations described and claimed herein provide systems and methods for processing liquefied natural gas (LNG). In one implementation, a dry feed gas is received. The dry feed gas is chilled with clean vapor from a heavies removal column to form a chilled feed gas. The chilled feed gas is partially condensed into a vapor phase and a liquid phase. The liquid phase retains freezing components. The freezing components are extracted using a reflux stream in the heavies removal column. The freezing components are removed as a condensate. The vapor phase is compressed into a clean feed gas. The clean feed gas is free of the freezing components for downstream liquefaction.

Systems and processes for detecting leaks into a refrigeration system having a heat exchanger where the process side is configured to operate at a higher pressure than the refrigerant side. The system includes a refrigerant circulation system including a refrigerant feed pipe fluidly connected to and configured to provide a refrigerant to an inlet of the refrigerant side of the heat exchanger, as well as a refrigerant effluent pipe fluidly connected to and configured to receive a refrigerant from an outlet of the refrigerant side of the heat exchanger. One or more sensors are provided, the sensors being configured to measure a property of the refrigerant, such as temperature, pressure, or flow rate, for example. Additionally, the system for detecting leaks includes a digital control system configured to provide an alert when a signal from at least one of the one or more sensors is indicative of a leak from the process side of the heat exchanger to the refrigerant side of the heat exchanger.

Method and system for removing high freeze point components from natural gas. Feed gas is cooled in a heat exchanger and separated into a first vapor portion and a first liquid portion. The first liquid portion is reheated using the heat exchanger and separated into a high freeze point components stream and a non-freezing components stream. A portion of the non-freezing components stream may be at least partially liquefied and received by an absorber tower. The first vapor portion may be cooled and received by the absorber tower. An overhead vapor product which is substantially free of high freeze point freeze components and a bottoms product liquid stream including freeze components and non-freeze components are produced using the absorber tower.

In a method for compressing a gas that is to be separated in a low-temperature CO.sub.2 separation unit using at least one partial condensation step and/or at least one distillation step, the gas that is to be separated has a variable composition and/or variable flow rate, the gas that is to be separated is compressed in a compressor to produce a compressed gas and the inlet pressure of the gas that is to be separated, entering the compressor, is modified according to the CO.sub.2 content and/or the flow rate of the gas that is to be separated so as to reduce the variations in volumetric flow rate of the gas that is to be separated entering the compressor.

The present disclosure provides a method for separating a feed stream in a distillation tower. The method may include forming solids in a controlled freeze zone section of the distillation tower; emitting radiation from a first radiation source in the controlled freeze zone section while the controlled freeze zone section forms no solids; detecting radiation emitted by the first radiation source as a first radiation level; detecting radiation emitted by the first radiation source as a second radiation level after detecting the first radiation level; and determining whether the solids adhered to at least one of on and around a first mechanical component included in the controlled freeze zone section based on the first radiation level and the second radiation level.

A method of designing, constructing, and operating a hydrocarbon gas treatment plant is disclosed. A target hydrocarbon production range for a hydrocarbon gas meeting a required product specification is established. A cryogenic distillation column is designed and constructed with a vapor capacity to meet the target hydrocarbon production range. A variable feed refrigeration system is incorporated to cool an inlet feed of the hydrocarbon gas. The variable feed refrigeration system is designed to handle the target hydrocarbon production range and a wide range of contaminant concentrations in the inlet feed. A variable bottoms heating system is incorporated to handle heating duties associated with the wide range of contaminant concentrations in the inlet feed. A variable bottoms pumping system is incorporated to handle liquid flows associated with the wide range of contaminant concentrations in the inlet feed.

The present disclosure provides a method for separating a feed stream in a distillation tower. The method includes operating a controlled freeze zone section in a distillation tower that separates a feed stream at a temperature and pressure at which the feed stream forms a solid in the controlled freeze zone section, wherein the feed stream includes a first contaminant; maintaining a melt tray assembly in the controlled freeze zone section; introducing the feed stream to the controlled freeze zone section; and accumulating a liquid in the melt tray assembly until the liquid is at a predetermined liquid level in the controlled freeze zone section, by: feeding a second contaminant to the controlled freeze zone section; and adding the second contaminant to the melt tray assembly, wherein the liquid comprises the second contaminant.