Method for treating sulfur-containing ammonia acidic water in sustainable aviation fuel production process

Abstract

The invention discloses a method for treating sulfur-containing ammonia acidic water in a sustainable aviation fuel production process. The method comprises the following steps: mixing the sulfur-containing ammonia acidic water with alkali liquor, and feeding the mixture into the upper part of a stripping tower; heating the bottom of the stripping tower, and stripping ammonia-containing gas from the top of the stripping tower; condensing ammonia-containing gas from the top of the steam stripping tower to obtain ammonia water, and feeding the ammonia water into an ammonia water tank; supplementing the desalted water according to the ammonia content of the ammonia water entering the ammonia water tank to obtain a product ammonia water; and the salt-containing water containing Na2S flows out from the bottom of the stripping tower, and is sent to a subsequent unit or directly discharged. The process complexity is greatly reduced, the operation reliability of the device is improved, the energy consumption and the operation cost are greatly reduced, and the method has remarkable advantages in investment, land occupation and the like. The salt-containing water produced by the method is low in content, and cannot cause adverse effects on sewage treatment or up-to-standard discharge after being mixed with sewage of a whole plant for treatment. The method is wide in application range, and is especially suitable for small-scale treatment of the sulfur-containing ammonia acid water.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of environmental protection and relates to a sulfur-containing amino acid water treatment method in a sustainable aviation fuel production process. BACKGROUND

[0002] In recent years, with the global concern about greenhouse gas emissions, sustainable aviation fuel (SAF) has been increasingly valued. With the increasing demand, the production capacity of SAF has also expanded rapidly. The global SAF production capacity increased from 0 to about 500,000 tons from 2019 to 2023. As of December 2024, the domestic SAF production capacity has expanded to 1,050,000 tons, and the under-construction and to-be-commissioned production capacity is nearly 3,000,000 tons. The main raw materials for SAF are mainly biomass such as animal and plant oils, agricultural and forestry waste, and waste oils. During the production process, these raw materials generally contain a small amount of sulfur and nitrogen elements, which are converted into hydrogen sulfide (H2S) and ammonia (NH3) respectively, entering the product or being discharged into the sulfur-containing ammonia wastewater. In the refining and chemical industry, the treatment of sulfur-containing ammonia acid water generally adopts a steam stripping process to produce ammonia-containing acid gas or acid gas and ammonia water / liquid ammonia. The purified water controls the H2S content ≯10 mg / L and the NH3 content ≯50 mg / L. The acid gas is sent to the sulfur unit to recover sulfur, and sulfur is produced by adopting CLAUS or complex iron process. The advantages of this method are mature technology, and the sulfur and ammonia in the acid water are recycled and utilized. However, in the SAF plant, due to the sulfur and nitrogen content of the raw materials being much lower than that of crude oil, the amount of sulfur-containing ammonia wastewater produced is very small. A SAF plant with a small-scale device has only about 100 kg / h of sulfur-containing ammonia wastewater, and a large-scale device has only about 10,000 kg / h of sulfur-containing ammonia wastewater. If the conventional treatment method is used, the process will be particularly long, and the scale will be too small for the device to operate. Neither from the economic point of view nor from the energy consumption point of view is it competitive. SUMMARY

[0003] The present application provides a sulfur-containing ammonia acid water treatment method in a sustainable aviation fuel production process, which has the characteristics of short process flow, simple control system, and low device energy consumption, and is especially suitable for the treatment of extremely small flow sulfur-containing ammonia wastewater in the SAF production process.

[0004] The present application provides a sulfur-containing ammonia acid water treatment method in a sustainable aviation fuel production process, which has the characteristics of short process flow, simple control system, and low device energy consumption, and is especially suitable for the treatment of extremely small flow sulfur-containing ammonia wastewater in the SAF production process.

[0005] 1) The sulfur-containing ammonia acid water is mixed with lye and then enters the upper part of the stripping tower;

[0006] 2) stripping tower bottom heating, ammonia-containing gas from the stripping tower top stripping out;

[0007] 3) ammonia-containing gas from the top of the stripping tower after condensation to obtain ammonia water, into the ammonia water tank;

[0008] 4) according to the ammonia content of the ammonia water into the ammonia water tank to supplement the desalted water, to obtain the product ammonia water;

[0009] 5) salt-containing water containing Na2S flows out from the bottom of the stripping tower, sent to the subsequent unit or directly discharged.

[0010] Further, according to the pH value of the stripping tower bottom liquid, the amount of lye added in step 1) is adjusted to control the pH value of the tower bottom liquid in the range of 9-11.

[0011] Further, the lye in step 1) is one or a mixture of two or more of NaOH, KOH, Ca(OH)2, Mg(OH)2, configured into a 5%-50% mass concentration aqueous solution for use.

[0012] The purpose of the lye includes: the lye reacts with hydrogen sulfide in the acidic water to achieve desulfurization; adjust the pH value, so that NH4 + ion in the acidic water reacts to form gaseous ammonia, promoting its removal from water. Taking NaOH lye as an example, the following reactions mainly occur:

[0013] NH4HS=NH4 + +HS -

[0014] HS - =H + +S 2-

[0015] NH3·H2O=OH - +NH4 +

[0016] NaOH=OH - +Na +

[0017] Na + +S 2- =Na2S

[0018] OH - +NH4 + =NH3(g)+H2O

[0019] H + +OH - =H2O

[0020] Total reaction:

[0021] 2NaOH + H2S = Na2S + 2H2O

[0022] NaOH + NH4 + = Na + + NH3 + H2O

[0023] Further, the heating mode of the stripping tower bottom in step 2) is to use a reboiler or an electric heater outside the stripping tower, or to use a reboiler or an electric heater inside the stripping tower.

[0024] Further, the heating mode of the stripping tower bottom in step 2) is to directly introduce steam or high-temperature purified flue gas into the stripping tower.

[0025] The heating of the stripping tower bottom provides heat for the stripping tower, and promotes the separation of ammonia gas.

[0026] Further, the salt-containing water containing Na2S in step 5) is obtained by membrane separation or evaporation to obtain Na2S product.

[0027] Further, the stripping tower, the reboiler and the ammonia water tank can be separately provided or can be provided in a segmented manner in the same tower to achieve isolation between segments through a riser and an internal condenser.

[0028] Compared with the traditional treatment process, the present application has the following beneficial effects:

[0029] (1) For ammonia-containing acidic water, high-concentration ammonia gas can be obtained only by double-tower stripping or single-tower pressurized side-draw ammonia extraction technology, and then liquid ammonia or ammonia water can be obtained after three-stage fractionation, ammonia refining and pressurization, and the treatment capacity is generally several tens of tons per hour to operate normally. For acidic water with a small treatment capacity, the present application only needs one tower and one tank to treat the sulfur-containing and ammonia-containing acidic water of the whole plant, the process complexity is greatly reduced, the device operation reliability is improved, and the investment, land occupation and the like have significant advantages.

[0030] (2) Compared with the traditional treatment process, the method of the present application can greatly reduce energy consumption and operating cost.

[0031] (3) The amount of salt-containing water produced by the method of the present application is small, and after mixing with the whole plant wastewater, the treatment will not adversely affect the wastewater treatment or standard discharge.

[0032] (4) The present application has a wide range of applications, and is especially suitable for the treatment of small-scale sulfur-containing and ammonia-containing acidic water. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 The present application adopts a steam stripping treatment method process flow diagram;

[0034] Figure 2This is a schematic diagram of the process flow of the high-temperature purified flue gas stripping treatment method of the present invention;

[0035] In the picture:

[0036] 1. Stripping tower; 2. Mixer; 3. Condenser; 4. Ammonia tank; 5. Water seal tank; 6. Packing material. Detailed Implementation

[0037] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The specific embodiments do not limit the scope of protection claimed by the present invention.

[0038] Example 1

[0039] A certain 20,000-ton / year SAF plant has sulfur-containing amino acid water with the following composition.

[0040]

[0041] When using the method of this invention, the sulfur-containing amino acid water and 59.8 kg / h of 12 wt% NaOH solution are first thoroughly mixed in mixer 2 before entering the system. Figure 1 The stripping tower 1 shown is located at its upper part, and the stripping gas from the bottom of the tower is in full contact with the packing 6. At the bottom of the stripping tower, 63.9 kg / h of 1.0 MPa steam is injected as a heat source to heat and strip the acidic water, promoting the stripping of ammonia from the water.

[0042] The ammonia-containing gas discharged from the top of stripping tower 1 is condensed by condenser 3 and then enters ammonia water tank 4. In the tank, approximately 9.7 kg / h of demineralized water is injected to absorb all the undissolved ammonia gas, resulting in 28.0 kg / h of 20% wt ammonia water, which is then sent out as the product.

[0043] The bottom of the stripping tower discharges 319.3 kg / h of brine containing 2.19% Na2S, which is then sent to a wastewater treatment plant for further processing.

[0044] Example 2

[0045] A certain 200,000-ton / year SAF plant has sulfur-containing amino acid water with the following composition.

[0046]

[0047] When using the method of this invention, the sulfur-containing amino acid water and 94.1 kg / h of 30 wt% NaOH solution are first thoroughly mixed in mixer 2 before entering the solution. Figure 2The stripping tower 1 is shown in the upper part, and the stripping gas from the bottom is in full contact with the packing 6. The stripping tower bottom is purified by high temperature flue gas 2087.3 kg / h at 300℃ as a heat source, and the CO2 in the purified flue gas is 6.6%; H2O: 5.47%; N2: 85.83%; O2: 2.1%, the acidic water is heated and stripped, and the ammonia is stripped from the water.

[0048] The ammonia-containing gas discharged from the top of the stripping tower 1 is condensed by the condenser 3 and then enters the ammonia water tank 4, in which about 30.3 kg / h of desalted water is injected by spraying to absorb all the undissolved ammonia gas to obtain 20%wt ammonia water 135 kg / h, which is sent out of the device as a product.

[0049] The non-condensable gas containing N2 and O2 discharged from the ammonia water tank 4 is absorbed by the water seal tank 5 to absorb the ammonia therein and is safely discharged from the top.

[0050] The stripping tower bottom discharges 3847.3 kg / h of salt water containing 0.72% Na2S and 8.63% Na2CO3, and the rest is water, which is sent to the sewage treatment plant for further treatment.

[0051] The above is only a typical example of the present application and does not limit the present application in any form. Any skilled person in the art, without departing from the scope of the present application, can make changes or modifications to the above technical content, which should be regarded as equivalent examples of equivalent changes. Any equivalent change made to the above examples without departing from the technical solution of the present application, according to the technical essence of the present application, is within the scope of the present application.

Claims

1. A method for treating sulfur-containing amino acid-rich water during sustainable aviation fuel production, characterized in that, Includes the following steps: 1) The sulfur-containing amino acid water is mixed with the alkaline solution and then enters the upper part of the stripping tower; 2) Heating at the bottom of the stripping tower to strip ammonia-containing gas from the top of the stripping tower; 3) The ammonia-containing gas coming out from the top of the stripping tower is condensed to obtain ammonia water, which then enters the ammonia water tank; 4) Add demineralized water according to the ammonia content of the ammonia water entering the ammonia water tank to obtain the product ammonia water; 5) The brine containing Na2S flows out from the bottom of the stripping tower and is sent to subsequent units or discharged directly.

2. The method for treating sulfur-containing amino acid-based water during sustainable aviation fuel production according to claim 1, characterized in that: Adjust the amount of alkali added in step 1) according to the pH value of the bottom liquid of the stripping tower, and control the pH value of the bottom liquid within the range of 9 to 11.

3. The method for treating sulfur-containing amino acid-based water during sustainable aviation fuel production according to claim 1, characterized in that: Step 1) The alkaline solution is one or more of NaOH, KOH, Ca(OH)2, and Mg(OH)2, prepared as an aqueous solution with a mass concentration of 5% to 50% for use.

4. The method for treating sulfur-containing amino acid-rich water during sustainable aviation fuel production according to claim 1, characterized in that: Step 2) The bottom heating method of the stripping tower is to use an external reboiler or electric heater, or to use a built-in reboiler or electric heater.

5. The method for treating sulfur-containing amino acid-based water during sustainable aviation fuel production according to claim 1, characterized in that: Step 2) The bottom heating method of the stripping tower is to directly introduce steam or high-temperature purified flue gas into the stripping tower.

6. The method for treating sulfur-containing amino acid-based water during sustainable aviation fuel production according to claim 1, characterized in that: In step 5), the salt water containing Na2S is separated into Na2S products by membrane separation or evaporation.

7. The method for treating sulfur-containing amino acid-based water during sustainable aviation fuel production according to claim 4, characterized in that: The stripping tower, reboiler, and ammonia tank can be installed separately or in sections within the same tower, with isolation between sections achieved through riser pipes and built-in condensers.

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