Hydrogen Generators

Types of it

Hydrogen Gas Generation using the advanced Pressure Swing Adsorption technology has been gaining ground as the requirement of pure quality Hydrogen gas is increasing day by day in various industries. From Chemical industry to iron and steel to emerging fuel cell application Hydrogen gas is increasingly gaining prominence. Pressure Swing adsorption technologies used in the hydrogen production are cost effective along with being environment friendly. Hydrogen generation using PSA can be done in three ways. They are the following:

• Ammonia Cracking Units
• Methanol Reforming Based
• LPG or LNG based onsite Generator

Ammonia Cracking Units:
Typically an ammonia cracker unit produces Cracked Ammonia ( NH3) Gas using the ammonia in Anhydrous form from cylinders. Usually cracked ammonia contains around 75% Hydrogen and 25% Nitrogen. The product gas is dry and free of oxygen.

The production of cracked gas amounts to 2. 63 NM3/ Kg of ammonia feed stock. The residual ammonia contents are less than 20 ppm and dew points are up to (-) 500 C.

As certain applications require the need of gas having very low residual ammonia contents and low gas dew point. Here comes the PSA technology, cracked ammonia is passed through a special grade of desiccant in twin tower Pressure Swing Adsorption system (PSA Type). It has the properties of adsorption of Nitrogen molecules at much faster rate than hydrogen molecules. After this purification process, the residual ammonia contents generally fall below 3 ppm and dew point of gas shows considerable improvement up to (-) 80.

The Following table gives a brief technical information on ammonia crackers based Hydrogen Gas Generators usually in use:

Plant Capacity	1- 500 Nm3/Hr
Product Specifications	Hydrogen : 99. 5% Nitrogen : Up to 0. 5% Oxygen : Nil Dew Point : (-) 70°C Pressure : 3. 5 to 25 Ba
Applications	Heat Treatment Edible Oil Industry Chemical & Petrochemical Industry Chemical Process Industry

Methanol Reforming Based Hydrogen Generator:
In this process, first methanol and water is mixed in specific ratio and allowed to pressurize. This mixture passes through evaporator, metering pump and then into the super heater. This hot gas is then entered into a reactor. Methanol reforming and the shift reaction, takes place in the catalytic reactor of fixed beds to simultaneously form Hydrogen and Carbon Dioxide. The reformed gas is then entered into a set of PSA system. It separates all impurities through the adsorption and separation processes. The four adsorbers that are generally used shift regularly, alternating between adsorption and regeneration, according to the program guidelines in a closed loop. Thus in this way raw gas feeds and hydrogen is withdrawn continuously.

Illustration showing process flow for a Methanol based Hydrogen Gas Generators

List of Equipment No. Description Quantity 1. Heat exchanger 1 2. Condenser 1 3. Reformer 1 4. Evaporation super-heater 1 5. Raw material liquid storage tank 1 6. Metering pump for feedstock solution 1 7. Gas –liquid seporation buffer

Technical Specification Description Specification Hydrogen purity =>99. 99% (V/V) Hydrogen pressure 5 Kg/cm2g Temperature of the product At ambient temp.

LPG or LNG based on-site Hydrogen Gas Generator:
As the world's concern turns to environmental problem regarding a clean energy. Hydrogen is gaining attention as the next step ahead in its utilization as future energy. Already industrial hydrogen is popularly used by chemical industry. It's demand has been kept increasing every year. Though a large scale reformer that produces hydrogen from gases like LNG or LPG has been widely used, however smaller ones were not available because it did not fulfill the requirements in terms of system cost, operation, etc. But a new compact size on-site hydrogen generator has just fulfilled such a need. It comes with easy installation and operation. This PSA based Hydrogen Gas Generator uses Liquefied natural gas or LPG as it's feedstock and produces high purity (99. 999% or more) hydrogen at cheaper cost.

The system consists of two parts. First one is a steam reforming process that reforms the LNG or Liquefied Petroleum gas to hydrogen rich gas. The next part consists of Pressure Swing Adsorption system which purifies this gas to high purity.

After the process of steam reforming reactions, reforming gas that consists 75% hydrogen or more is purified to 99. 999% by carrying out the process of PSA for removal of the ingredients other than hydrogen (CO2,CO, CH4, moisture, etc.).

Principle of System

Features of LPG or LNG Based On Site Hydrogen Generator:

• Cheaper Production costs as efficient system reduces production costs by at least 10~20% as compared to compressed hydrogen.
• Cater to extensive Hydrogen Demand as shown in the following table.

  Production Capacity	40m3N/h 50m3N/h	75m3N/h	100m3N/h	200m3N/h
  Hydrogen Purity	99. 999% or more
  Plot Size ( Main Skid )	18m2 ( 3m x 6m )	24. 5m2 ( 3. 5m x 7m )	29. 8m2 ( 3. 5m x 8. 5m )	40. 3m2 ( 3. 5m x 11. 5m )
  Skid mounted packaged

• No manual operation as automatic sequencer enables automatic operation.
• Special Utilities are not required as built-in utility includes in itself water purity device, cooling water and instrument air supplier to avoid any additional preparation.
• Units are mostly skid mounted for easy installation.