Method and a system for separating and treating impurities from a hydrogen chloride liquid mixture

A system for separating and treating impurities from a hydrogen chloride liquid mixture, comprising:

• a gas-liquid separation column having a top and a bottom, an inlet stream comprising a liquid mixture of hydrogen chloride and impurities comprising ammonium chloride, an outlet stream comprising hydrogen chloride gas at the top of the gas-liquid separation column, a first liquid phase flow outlet stream at the bottom of the gas-liquid separation column, wherein the first liquid phase flow comprises impurities comprising ammonium chloride, and a first liquid phase flow pipeline connected to the bottom of the gas-liquid separation column;
• a neutralizing tank connected via the first liquid phase flow pipeline to the bottom of the gas-liquid separation column for receiving said first liquid phase flow comprising impurities,
• and neutralizing said liquid phase flow comprising impurities with an alkaline liquid in said neutralization tank to yield a neutralized solution;
• and
• a waste liquid treatment device for receiving and treating said neutralized solution from said neutralization tank
• wherein the system further comprises a pipeline for a hydrogen chloride liquid mixture from a production site for preparing isocyanate with phosgenation which comprises the inlet stream comprising the liquid mixture of hydrogen chloride and impurities comprising ammonium chloride.

A system for separating and treating impurities from a hydrogen chloride liquid mixture, comprising:

• a gas-liquid separation column having a top and a bottom, an inlet stream comprising a liquid mixture of hydrogen chloride and impurities comprising ammonium chloride, an outlet stream comprising hydrogen chloride gas at the top of the gas-liquid separation column, a first liquid phase flow outlet stream at the bottom of the gas-liquid separation column, wherein the first liquid phase flow comprises impurities comprising ammonium chloride, and a first liquid phase flow pipeline connected to the bottom of the gas-liquid separation column;
• a buffer tank connected via the first liquid phase flow pipeline, for buffering said first liquid phase flow comprising impurities,
• a neutralizing tank connected to the buffer tank via a second liquid phase flow pipeline, for neutralizing the buffered liquid phase flow comprising impurities with an alkaline liquid to form a neutralized solution;
• wherein the first liquid phase flow comprising impurities sequentially flows into said buffer tank from the bottom of said gas-liquid separation column through said first liquid phase flow pipeline, and then flows into the neutralization tank through the second liquid phase flow pipeline from the buffer tank,
• a waste liquid treatment device for receiving and treating the neutralized solution from the neutralization tank and
• wherein the system further comprises a pipeline for a hydrogen chloride liquid mixture from a production site for preparing isocyanate with phosgenation which comprises the inlet stream comprising the liquid mixture of hydrogen chloride and impurities comprising ammonium chloride.