JPH0689338B2 - Method for removing mercury in liquid hydrocarbons - Google Patents

Description

Detailed Description of the Invention a. Object of the invention [Industrial field of application] Natural gas condensate, which is a liquid hydrocarbon, has recently begun to be used as a raw material for ethylene. Natural gas condensate contains a maximum of several ppm of mercury, depending on the origin. Mercury needs to be removed because it causes corrosion of the low temperature heat exchanger, poisoning of the catalyst, and deterioration of working environment.

[Prior Art] Natural gas condensate contains elemental mercury, ionic mercury,
It contains organic mercury (hardly reactive mercury), etc., and its amount varies depending on the place of origin. Elementary mercury is an adsorbent, ionic mercury can be removed with a Na ₂ S aqueous solution, and organic mercury can be removed with a solid acid.However, when organic mercury is removed with a solid acid, polar compounds that coexist in the condensate are also adsorbed. The amount of mercury adsorbed was small and there were some problems in practical use.

[Problems to be Solved by the Invention] The present invention provides a method for improving the removal rate of organic mercury as well as elemental mercury and ionic mercury. The purpose is to provide a mercury removal method.

B. Structure of the Invention [Means for Solving the Problems] The method for removing mercury and mercury compounds contained in a liquid hydrocarbon of the present invention is a method of converting a liquid hydrocarbon into the formula MM′Sx (M is an alkali metal or ammonium group, M ′ is Contact with an aqueous solution containing a sulfur compound represented by hydrogen, an alkali metal or an ammonium group, and x represents a number of 1 to 6, particularly a mixed aqueous solution of Na ₂ S ₄ and Na ₂ S at a temperature of 40 ° C. or higher. It is characterized by

Examples of the sulfur compound represented by the formula MM′Sx include Na ₂ S and Na
HS, K ₂ S, KHS, (NH ₄ ) ₂ S, NH ₄ HS, Na ₂ S ₄ , K ₂ S _{4 and the} like can be mentioned. In the case of polysulfides with x of 2 or more, sulfides with different x Often a mixture. Out of these
Na ₂ S, Na ₂ S ₄ , K ₂ S, K ₂ S _{4 and the} like are particularly preferable.

The removal rate of mercury and mercury compounds can be increased by contacting the liquid hydrocarbon with an aqueous solution of these compounds at a temperature higher than room temperature, usually 40 to 200 ° C.

According to the present invention, it is possible to remove mercury and mercury compounds in various liquid hydrocarbons, particularly liquid hydrocarbons obtained from natural gas condensate or petroleum associated gas.

In carrying out the present invention, when mercury is removed from the natural gas condensate, it is desirable to wash the natural gas condensate with water in advance. Some natural gas condensates contain ethylene glycol and surfactants used in the production process, and these can be mixed with an aqueous solution containing a sulfur compound represented by the formula MM'Sx to form an emulsion by heating. Yes Post-processing is troublesome. The purpose of washing with water is to remove the above compounds.

Natural gas condensate containing elemental mercury, ionic mercury, organic mercury (hardly reactive mercury), etc. is used as Na ₂ S, for example.
_{4 When} mixed with an aqueous solution and heated, all mercury components turn into HgS, and the HgS dissolves in the Na ₂ S ₄ aqueous solution. Heating is necessary to remove organic mercury (hardly reactive mercury). It is preferable to heat to 50 to 100 ° C., because the reaction rate is slow at low temperature, while at high temperature it becomes a high pressure device due to the vapor pressure. The HgS produced in the aqueous solution of Na ₂ S ₄ alone
However, this can be solved by using Na ₂ S together.

The concentration of the aqueous solution of the sulfur compound represented by the formula MM'Sx is not particularly limited, but is usually 1% to 10%. At a concentration of 1% or less, a decrease in reactivity was observed, and at a concentration of 10% or more, a particularly remarkable increase in reactivity was not observed.

The monosulfide represented by the formula MM ′S is converted into the formula MM′Sx (x is 2 to 6).
To be used in combination with the polysulfide represented by
This is to enhance the solubility of HgS produced as described above.

In this case, the ratio of monosulfide to polysulfide is not particularly limited, but for example, the mixing (weight) ratio of Na ₂ S ₄ and Na ₂ S is 10/1 to 1
/ 10 is preferable.

It is desirable to wash the liquid hydrocarbon that has been mixed with an aqueous solution of a sulfur compound represented by the formula MM'Sx and heat-treated to remove all mercury components. This is intended to remove these sulfur compounds entrained in the liquid hydrocarbons.

The term "organic mercury (hardly reactive mercury)" as used herein refers to a mercury compound that cannot be removed by stirring and mixing the condensate with an aqueous Na ₂ S ₄ solution at room temperature for 60 minutes. It is presumed that the refractory mercury in the condensate is organic mercury, because it does not react with aqueous Na ₂ S ₄ solution at room temperature.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

[Example 1] Two types of natural gas condensates A and B shown in Table 1 below, which were produced in different regions, were used as raw materials, and a test for removing mercury therein was conducted.

The mercury content in the raw material was measured by the gold amalgam flameless atomic absorption method. In the data shown in Table 1, the amount of organic mercury was determined by mixing the raw material with an aqueous 5% Na ₂ S ₄ solution at room temperature (20 ° C.) for 60 minutes with stirring and then analyzing the mercury remaining in the raw material.

50 ml of a 5% Na ₂ S ₄ aqueous solution and 50 ml of the raw material washed with water were heated and stirred in a glass autoclave for 1 hour at a predetermined temperature.
The oil phase and the aqueous phase were separated and the mercury remaining in the oil phase was analyzed. The results are shown in Table 2.

The results of the same treatment with a 5% Na ₂ S ₄ aqueous solution are also shown. From the results shown in Table 2, it was found that the higher the temperature, the more effective it was. Also, under all temperature conditions tested, Na
Towards the Na ₂ S ₄ from the ₂ S it was effective.

[Example 2] Regarding the natural gas condensate A shown in Table 1, 5
An experiment was performed in the same manner as in Example 1 except that a mixed aqueous solution of 3% Na ₂ S and 3% Na ₂ S ₄ was used. As a result of processing at 100 ℃,
The residual mercury concentration was 9 ppb, which was not different from that of Na ₂ S ₄ alone aqueous solution.

However, the solubility of mercury was changed between Na ₂ S ₄ alone solution and Na ₂ S ₄
A comparison of a mixed aqueous solution of Na ₂ S with a 5% Na ₂ S ₄ single aqueous solution was 1000 ppm, and with a mixed aqueous solution of 5% Na ₂ S ₄ and 3% Na ₂ S was 3%. It was about 30 times higher.

C. Effect of the Invention 1) The removal rate of mercury and mercury compounds can be improved.

2) It is possible to remove organic mercury as well as elemental mercury and ionic mercury.

3) The process is simple.

4) The treatment liquid has a long life and long-term continuous operation is possible.

5) Since no solid (HgS) is generated, operation management of the device is easy.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toru Matsuzawa 2110 Sakimachi, Hino, Aichi Prefecture, Kinoura Research Institute, Jiki Co., Ltd. (56) References JP-A-56-50992 (JP, A) JP-A-56- 157489 (JP, A)

Claims (5)

[Claims] 1. A liquid hydrocarbon containing sulfur represented by the formula MM'Sx (M is an alkali metal or ammonium group, M'is hydrogen, an alkali metal or an ammonium group, and x is a number from 1 to 6). A method for removing mercury and mercury compounds contained in liquid hydrocarbons, which comprises contacting with an aqueous solution containing the compound at a temperature of 40 ° C or higher. 2. The mercury and mercury compound contained in the liquid hydrocarbon according to claim 1, wherein the aqueous solution containing the sulfur compound represented by the formula MM'Sx is a mixed aqueous solution of monosulfide and polysulfide. Removal method. 3. The method for removing mercury and mercury compounds contained in liquid hydrocarbons according to claim 2, wherein the mixing ratio of monosulfide and polysulfide is 10/1 to 1/10 by weight. 4. The method for removing mercury and mercury compounds contained in a liquid hydrocarbon according to claim 2 or 3, wherein the monosulfide is Na ₂ S and the polysulfide is Na ₂ S ₄ . 5. A liquid hydrocarbon containing an aqueous solution containing a sulfur compound.
The method according to claim 1, wherein the contact is performed at a temperature of 40 to 200 ° C.
A method for removing mercury and mercury compounds contained in the liquid hydrocarbon according to the third or fourth aspect.