Gasification of liquefied gases

As a rule, the system of industrial gases gasification is a part of the industrial gases storage system. Industrial gases storage is a stable object placed within the area of industrial gases production.  The storage equipment includes: liquefied gas tank, cryogenic pumps, gasifiers (evaporators), piping valves, Automatic process control system, the systems of emergency alarm, fire-extinguishing, video control.

There are two alternative options of the gasification scheme. Option 1 – evaporation with the use of atmospheric vaporizer and reheating using small steam reheater (if required) with condensate drain into a small storage. Option 2 – evaporation with the use of steam-heated evaporator and condensate drain into storage container using condensate extraction pump. Both options involve using shutoff and control valves with pneumatic drives and electric explosion-proof drives.

Pipelines for liquefied gas transportation are made with vacuum insulation, which is currently the most efficient approach with reduced heat loses. Pipelines are equipped with high-quality shutoff and control valves.

From the storage tank, liquefied gas is pumped by vertical centrifugal cryogenic pump. After cryogenic pump, pumped liquid oxygen is fed to the plate-finned gasifier (evaporator) of atmospheric type or with steam heating.  Gasifier produces sales gas with design pressure and capacity.

Plant is completed with the Automatic process control system. Functions performed by the process control system: tank’s parameters checkout (level, pressure, temperature), cryogenic pump working parameters and condition, gate valves position, processing signals of fire extinguishing, observation, access systems. Plant’s control desk installs in the separate control room without integration into the central automatic control system of the Air separation unit.

1. Cryogenic products storage tanks, consist of inner and external tanks with vacuum perlite insulation, operating medium – liquefied gas.

2. Cryogenic centrifugal pump (2 pieces).

3. Atmospheric vaporizers system consisting of: atmospheric vaporizers, steam heater, intermediate condensate gathering tank, condensate extraction pump, condensate storage tank.

4. Oxygen evaporation system with the steam heating consisting of: steam-heated evaporator, intermediate condensate gathering tank, condensate extraction pump, condensate storage tank.

5. Cryogenic pipeline with vacuum perlite insulation.

6. Pipeline fittings.

7. Based on the software and hardware complex Automatic control system.

Cryogenic atmospheric vaporizer is the most energy-efficient equipment for the gasification of liquefied air separation products. The gasification of cryogenic liquids does not require energy consumption because ambient energy is used as a heat source.

In addition, ambient evaporation scheme also includes steam reheater, which is designed for heating gasified gas to the temperature +10°С at an ambient temperature below +30°С.  The need of reheating is caused by the atmospheric vaporizer’s general temperature characteristic.

Along with including steam reheater to the system, arises the need of condensate drain.  For this purpose, the system consisting of next elements is used: intermediate condensate gathering tank, from the condensate drain of the reheater condensate gravity flows to this gathering tank. Condensate extraction pump, which extracts condensate from the intermediate condensate-gathering tank into the condensate storage tank; condensate storage tank where it is collected for subsequent natural cooling to 40°С and for disposal either into circulation water cycle or into drain system.

Advantages of steam evaporation system are in much smaller area required for equipment placement. Disadvantages of such system – the consumption of steam, technical water, electricity and the need for condensate drainage.