Cracker ammoniac NH3, générateur d'hydrogène pour la génération d'hydrogène H2, formant le gaz H2/N2

Ammonia Cracker
Crystec Technology Trading GmbH

Ammonia Cracker for the Generation of Forming Gas.

Hydrogen is indispensable for the bright hardening of metals. But, viewed from the standpoint of safety, hydrogen gas is by no means an advantageous atmosphere. Dissociated ammonia atmosphere or forming gas is the only furnace atmosphere that can make up the demerits of hydrogen and function nearly 100% as if it were hydrogen gas. There are cases where forming gas cannot replace pure hydrogen, but such cases are very rare. For almost all applications involved, forming gas atmosphere will answer the purpose.

An ammonia cracker, NH3-Cracker or hydrogen generator is used for the production of forming gas. Hydrogen and Nitrogen are generated in a cost effective way in a volume ratio of 3 : 1 or in a weight ratio of 14 : 3. Capacities from 25m3/h to 150m3/h are available.

The NH3 is coming from bottles or from an ammonia tank. The ammonia gas is pre-heated in a heat exchanger and vaporizer and then cracked in the main furnace unit. The furnace is electrically heated by special LGO heating elements.

ammonia cracker, graphic

The dissociation of ammonia gas NH3 takes place at a temperature of 920°C in the presence of a special nickel catalyst in an electrically heated furnace.
2 NH3 arrow N2 + 3 H2
The cracked gas then passes the heat exchanger for cooling and for pre-heating the incoming gas. This way and in combination with the low power consuming LGO heating elements, it can be made sure that only a minimum of electricity has to be used for the cracking process.

Gas Generator (Koyo Thermo Systems)

Features:

  • Light thermal mass heater: Comparing to conservative type brick furnace, there is lots of reduction in heat-up time, power consumption, footprint.
  • Stable gas generation: Tube type retort integrated in round electrical heater can generate cracking gas stable.
  • Safety feature: Excess temperature protection, over pressure, thermocouple burnt alarm, etc. can maintain the system safe.
  • Save footprint, easy operation: Operation switch install on front panel. Insulator got thinner and can realize less footprint.

Wasserstoffgenerator, Formiergasgenerator

As a result of complete dissociation into hydrogen and nitrogen, very little undissociated ammonia remains and the dew point temperature of the resulting gas is very low (well below -30°C).

Gas Purifier

As an option and in order to reduce the dew point of the generated forming gas further, a special forming gas purifier is available. Using molecular sieve technology, the dew point of the generated gas can be reduced to less than -65°C. Two adsorber units are working in parallel, one for adsorbing moisture and un-cracked ammonia from the forming gas and the other one is heated for regeneration. Every 6 h the gas flow is changed automatically.

Applications for dissociated ammonia

The forming gas is used in conveyer furnaces and in tube furnaces for anneal processes in a reducing atmosphere, brazing, sintering, deoxidation, and nitrization. You will find more details about these furnaces in our Koyo Thermo Systems product overview.

Further application for forming gas
  • Brazing
  • Sintering
  • Deoxidization
  • Nitrization
  Metal anneal:
  • Stainless steel wire anneal
  • Metal powder anneal
  • Bimetal products anneal
  • Hydrogenation of organic compounds
  • Galvanization
  • Production of Forming Gas

Gas Properties

The gas generated by the dissociation of ammonia is forming gas. It consists of 75 Vol% hydrogen and 25 Vol% nitrogen.

Description Ammonia NH3 Hydrogen H2 Nitrogen N2
Molecular Weight

17,03

2,0158

28,0134

Boiling Point (BP) in °C

-33,35

-252,87

-195,8

Liquid Density at BP in kg/m3

682,1

70,0

804,0

Vapor Density at BP in kg/m3

0,8906

1,329

4,613

Density at RT in kg/m3

0,7710

0,0899

1,2506

Heat of Vaporization in kJ/kg

1368,2

451,9

199,2

Solubility in cold water in g/100ml

89,9

-

-

Cp in kJ/kg (1 atm, RT)

2,188

14,2

1,038

Cp/Cv (1 atm, RT)

1,31

1,41

1,40

Product types

Several sizes of ammonia crackers are available. Data is referred to standard pressure and temperature.

Model

Ammonia consumption
(m3/h NH3)

Ammonia consumption
(kg/h NH3)

Hydrogen generation
(m3/h H2)

Hydrogen generation
kg/h H2)

25 N m3/h

25

19

38

3,5

30 N m3/h

30

23

45

4

40 N m3/h

40

30

60

50

50 N m3/h

50

40

75

7

60 N m3/h

60

45

90

8

70 N m3/h

70

55

105

9

75 N m3/h

75

60

115

10

100 N m3/h

100

75

150

14

150 N m3/h

150

115

225

20

The conversion of the ammonia to hydrogen and nitrogen (volume ratio 3: 1) in the cracker is almost complete. Only small amounts (<30ppm) of ammonia gas remain in the cracked gas.
For the production of larger amounts of forming gas, several units can be installed in parallel.

Crystec will be pleased to engineer a cost effective system to satisfy your most demanding and exacting requirements.