Natural gas, hydrogen technology

    1, purified natural gas

    Reforming catalyst in the course vulnerable to poisoning and loss of activity of the impurities in the raw material, there are strict requirements, general requirements for the sulfur content of the raw gas after refining is less than 0.2PPm, chlorine less than 0.5PPm. Because natural gas contains trace amounts of sulfur, it must first gas desulfurization process. Since the sulfur contained in the organic and inorganic sulfur include two forms, it must first be converted to inorganic sulfur organic sulfur and then using zinc oxide (Zn0) desulfurization refining.

The basic reaction is as follows:

Thiols: RSH + H2 → RH + H2S

Sulfide: R1SR2 + 2H2 → R1H + R2H + H2S

Disulfide: R1SSR2 + 3H2 → R1H + R2H + 2H2S

Thiophene: C4H4S + 4H2 → C4H10 + H2S

COS: COS + H2 → CO + H2S

Carbon disulfide: CS2 + 4H2 → CH4 + 2H2S

ZnO (solid) + H2S = ZnS (solid) + H2O △ Ho 298 = -76.62kJ / mol

 2, steam reforming of natural gas

      Gas refined by a certain steam to carbon ratio mixed with water, and then the reformer convection section after preheating into the reformer radiant section. In the role of a catalyst, the occurrence of a complex steam reforming reaction, thereby producing a balanced mixture of hydrogen, methane, carbon monoxide, carbon dioxide and water. The main reactions are:

CH4 + H2O = CO + 3H2

CO + 3H2 = CH4 + H2O △ HO298 = -206kJ / mol

CO + H2O = CO2 + H2 △ HO298 = -41kJ / mol

      Mainly methane gas, steam reforming is a simple process, mainly the above reaction, the final product from the reaction gas composition determined by the balance ②③.

      Natural gas reforming reaction is highly endothermic reaction increased volume, low pressure, high temperature, high steam to carbon ratios favor the above reaction. After the reaction heat required for the process provided by the gas fuel reformer burner at the top of the high-temperature reformed gas reformer transformed gas steam generator heat exchanger temperature is lowered into the conversion section.

3, the conversion section

      By the conversion section to the conversion of gas into the shift reactor, shift reaction occurs in the role of a catalyst:

CO + H2O = CO2 + H2 △ HO298 = -41.4KJ / mol

Converting gas CO content decreased, while continuing to produce hydrogen. After the change in the air through the heat exchange heat recovery section, and then by cooler water diversion into the PSA section.

4, PSA purification process

  4.1 sorbent hole developed, rich internal surface area can be selectively mixed gas of certain types of physical adsorption of gases: the same pressure, high boiling gas adsorbent easy absorption, adsorption of low-boiling gases is not easy; different pressure, high pressure adsorption adsorption agent is increased, to reduce the adsorption capacity of the adsorbent at low pressure. By alternating pressure, selective adsorption properties of the adsorbent, the removal of hydrogen impurities. Companies have developed a multi-bed PSA plant, and constantly improve and perfect the program control, so PSA hydrogen recovery process has been greatly improved, operational reliability, flexibility has also been greatly improved.

  4.2 After cooling, the watershed after the change of gas into the PSA unit, adsorption to remove other impurities other than hydrogen (CH4, CO, CO2, H2O, etc.), the gas will be purified, adsorbed impurities and then vacuum the bed, purging the adsorbent is regenerated after further pressure adsorption. This process is in a process control system, under the command automatically performed again and again. Product hydrogen purity purified user requirements and the means.

 4.3 PSA regeneration mode

Cycle pressure swing adsorption (PSA) cycle of adsorption and regeneration, the adsorption process is pressurized adsorbent in the mixed gas of some component parts by unabsorbed by adsorption layer flows, when the adsorbent is strongly adsorbed after saturation component, the adsorption tower into the regeneration process requires, i.e. the desorption, or desorption process.
In the pressure swing adsorption (PSA) process, the adsorbent within the adsorber is relying on lower impurity partial pressure achieved in the industry means there are methods that can be employed:
1) reduce the adsorption pressure (pressure relief)
2) adsorption evacuated
 3) Rinse with product components

Second, the key equipment

1. Hydrogen Reformer

Reformer hydrogen plant is the core of the device, which is under high temperature, presence of hydrogen status of the operation of the furnace tube material and structure, there are strict requirements. Reformer tubes made of centrifugal HK-40 or HP-40 cast pipe, since high-temperature furnace tube, the design should take full account of thermal expansion problem.

2. PSA adsorbent bed

Pressure swing adsorption intermittent operation, for each bed is concerned, under high pressure adsorption, desorption at low pressure, so the pressure of the adsorbent bed by alternating the role of fatigue capacity in the design, manufacture sufficient attention to . Flow: 1 ~ 3000Nm3 / h

Third, natural gas, hydrogen equipment, technical parameters

 Flow: 2000 ~ 50000Nm3 / h

 Purity: 99 to 99.9999%

 Product pressure: 1 ~ 2.5Mpa