CS273956B1 - Method of sulphone removal from biogas - Google Patents

Abstract

Biogas is released through a porous material, watered by a solution of chelate bonded salts, whose complex-forming component is formed by ethylenediaminetetraacetic acid while maintaining pH between 7 and 9.

Description

(57) Biogas is permeated through a porous material, 'a solution of a chelate-bound salt, the complexing component of which is composed of ethylenediaminotetraacetic acid while maintaining a pH in the range of 7 to 9.

273 956 (13) Bl (51) Int. Cl. ⁵

OJ C 10 K 1/08

81

The invention relates to a process for removing sulfane from biogas by treating an aqueous solution of chelated iron salts. By washing the sulfane with solutions with a pH higher than 7, it is initially converted to hydrogen sulphide anions, which are then oxidized by a complexed iron salt.

The scrubbing efficiency of the solution is restored by oxidizing the gelatinous complexed salt to the ferric complex by contact with oxygen, most often air.

The optimum performance and effectiveness of the shut-off solution is achieved by using ethylenediaminotetraacetic acid as a complexing agent and maintaining a pH in the range of 7-9, which ensures a sufficient rate of absorption of sulfane and limits the absorption of carbon dioxide, which is a regular part of biogas.

A disadvantage of this process in the prior art process is that the scrubbing of the sulfane takes place separately from the regenerative oxidation of the reduced form of the scrubbing chelate solution. Sulfan scrubbing, which is carried out in Venturi scrubbers, requires a high consumption to provide the appropriate pressure mode for the apparatus. Vertical and horizontal absorbers, both upstream and downstream, or combined, are characterized by low liquid-biogas contact and therefore low efficiency.

Also columns with expanded metal or glass spirals did not work, especially in intermittent operation, because they are clogged by excreted sulfur. Their purchase costs are relatively high and the removal of sulfur deposits deposited therein is very difficult and expensive. Removal of sulfur from the scrubbing solution is difficult if the solution is not very gentle.

According to the invention, the process of removing sulfane from biogas by washing with an aqueous solution of chelated iron salts having a complexing component of ethylenediaminetetraacetic acid while maintaining a pH in the range of 7 to 9 is based on the fact that the biogas is passed through a layer of porous material. it is connected with a scrubbing aqueous solution of chelated iron salts. The porous material may be, for example, a foamed ceramic, such as fireclay, aerated concrete or a natural porous material, such as pumice or waste materials, such as a brown coal slag, etc.

The main advantage of the process according to the invention is that - during the desulfurization process, a large specific surface area reacts rapidly between the sulfone and the complex-bound ferric salt to form elemental sulfur which settles on the surface of the support material. the source of which may be air, either intermittently after the reaction capacity of the impregnated sorbent has been exhausted, or continuously by operating air, oxygen or oxygen-containing gas into the desulfurized gas.

Since the re-oxidation of the soaked chelate solution after reaction with the sulfane depends on its oxygen interface, this process proceeds quickly and efficiently on the large specific surface area of the porous materials.

Joining a mere layer of porous material with a scrubbing solution substantially reduces the amount of solution used in the desulfurization process, thereby reducing the economic cost of the chemicals used. By eliminating the necessity of pumping the scrubbing solution, it is not necessary to connect the corresponding pumps, thereby reducing operating energy costs. The need to remove sulfur from the circulating desulfurization solution is no longer necessary. Further improvement of the process economy is facilitated by the simultaneous combination of HgS capture and scrubbing solution recovery.

After the capacity of the cavities and pores is clogged with sulfur, either the material can be recovered by sulfur extraction according to known methods and reconnected with a desulphurizing chelate solution, or washed with a desulphurizing solution from the material and then deposited with the sulfur material in a landfill.

The process of the invention is described in more detail in the following examples.

Example 1

Gas containing 3 gm of hydrogen sulphide was conducted through a packed column of chamotte foam that was connected to a solution of ¹ mole of L složení0,1 ethylene diamine tetraacetic acid,

1 1 0.1 M FeS0 ₄ ®7 H ₂ 0 and 0.17 mol NaHCO ^ l ^ in an amount of 3% by volume. Volume column

CS 273956 Bl

1 loose charge of 1.2 m _{n of} model gas was released during intermittent regeneration, while the sorption capacity of the column had not yet been exhausted,

Example 2 • 3

A model gas containing 3 gm HgS was prepared through a 45 mm diameter and 600 mm high column filled with a brown coal slag. The slag was fed with the solution of Example 1 in an amount of 150 ml per liter of slag. A total of 1,000 L of model gas was passed through the column for repeated regeneration at a rate of 1 1 min · ^ · without detecting reduced desulfurization efficiency. * Excluded sulfur did not affect the desulfurization efficiency of the gas.

Claims (1)

I will invent the object A process for removing sulfane from biogas by scrubbing an aqueous solution of chelate-bound iron salts, the complexing component of which is ethylenediaminetetraacetic acid, while maintaining the pH of the solution in the range of 7 to 9, characterized in that the biogas is passed through a layer of porous material a scrubbing aqueous solution of chelated iron salts.