The sulfur recovery unit adopts a new technology of removing heat-stable salts in the amine liquid by using the amine liquid on-line purification facility.
The alcohol-amine process is the most widely used process to remove acidic components such as hydrogen sulfide and carbon dioxide from industrial gas streams such as natural gas and dry gas.
The basic process of the refining desulfurization process is to use water-soluble alkyl alcohol amines to absorb acid gases such as hydrogen sulfide and carbon dioxide and react to generate solvated alkyl alcohol amine salts.
The reaction is then reversed by thermal stripping to yield the solvated alkyl alcohol amine salt.
The reaction is then reversed by thermal stripping. With the continuous improvement of people’s awareness of the importance of gas desulfurization devices, more and more attention is paid to the quality management of solvent amines, and the purification and regeneration process of amine liquid is widely used.
The impurities in the amine solution mainly include solid suspended solids, hydrocarbons, thermal stable salts and degradation products. The presence of these impurities will cause foaming of the amine, increase the consumption of amine and steam, and affect the absorption effect of the amine solution. Seriously affect product quality, accelerate device corrosion, cause pipeline and equipment blockage, and thus affect the normal operation of the device.
THE PRINCIPLE OF AMINE DESULFURIZATION PROCESS AND THE HARM OF THERMALLY STABLE SALT
Amine desulfurization technology uses N-methyl diethanolamine solution (MDEA) with a concentration of 20% to 30% as a desulfurization agent, which is used in liquid hydrocarbon extraction tower, dry gas desulfurization tower, circulating hydrogen desulfurization tower, and sulfur recovery respectively. In the tail gas desulfurization tower, gases such as liquid hydrocarbons, dry gas, circulating hydrogen, and H2S in tail gas are removed.
The desulfurized rich liquid goes through the solvent regeneration system, the regenerated lean liquid is cooled and recycled, and the acid gas from the top of the regeneration tower is cooled and separated to go to the sulfur recovery device.
In order to keep the solvent clean, the rich liquid from the upstream device first passes through the wedge wire filter element, and then an activated carbon filter and a bag filter are set at the outlet of the lean liquid pump of the device. However, such filtration and purification facilities only remove mechanical impurities and have low efficiency. The long-term operation is difficult and the effect is poor, and various impurities in the system cannot be completely removed. The entire amine liquid system has serious pollution, high energy consumption, and poor desulfurization effect.
It also affects the payload of the amine solution. The accumulation of pollutants (mainly thermally stable salts), it affects the product quality, regeneration effect, and heat exchange efficiency.
The quality control of solvent amines has always been an important problem.
In the gas desulfurization treatment process, when the salts formed by the strong acidic components in the gas and liquid and the amine liquid cannot be decomposed under the heating conditions of the desorption tower, the amine liquid cannot be regenerated by heating, and this type of salt is a thermally stable salt.
Since the solvent amine with the same mole number of the anion of the thermally stable amine salt is bound (protonated) and cannot react with the acid gas, the processing capacity of the device is reduced, so in the old device, there will be liquefied gas with liquid, which affects the liquefaction of the tank area. air quality.
Moreover, hydraulic fluid is required every day, which increases the work intensity and also increases the danger, because sometimes liquefied gas will be pressed out, adding huge hidden dangers to the device.
INTRODUCTION TO THE FUNCTION AND PROCESS PRINCIPLE OF AMINE LIQUID ONLINE PURIFICATION FACILITY
In order to solve the thermally stable salt in the amine solution, the amine solution regeneration unit in the new sulfur recovery unit has added an amine solution online purification facility. Reduce equipment investment and equipment maintenance workload and costs.
The operation cost of the device is reduced, which is beneficial to the smooth operation of the device. The performance, failure, and economic indicators of the desulfurization unit are closely related to the change of solvent amine purity.
The amine liquid regeneration unit of the sulfur recovery unit adopts anion-exchange technology to pass the poor solvent containing heat-stable salt anions (such as thiosulfate, sulfate, thiocyanate, formate, oxalate, chloride ion) through the anion exchange resin bed（BLUSLOT has developed a high-efficiency resin trap filter for anion exchange resin beds）， The heat-stable salt anion is exchanged with OH-, the heat-stable salt anion in the amine solution is removed, and the solvent amine is reduced to achieve the purpose of purifying the amine solution.
When the resin is completely exchanged, the resin bed is regenerated with a strong alkali, and the regenerated resin bed is recycled.
The use of ion-exchange resin has strong resistance to amino acid and thiocyanate poisoning. The ion exchange resin has a strong anti-pollution ability and long service life, which greatly reduces the operating cost in terms of economic benefits, and achieves synchronous benefits with other refineries. The amine liquid online purification facility of this device adopts the amine purification SUU system.
- The thermal steady-state salt in the amine solution decreased to a great extent, and the quality of the treated desulfurizer was improved.
- Reduce the corrosion rate of the device, after the thermal steady state salt decreases, the device has no corrosion leakage point.
- Improve the processing capacity of amine liquid, and the adsorption capacity of solvent acid gas is improved.
- To reduce foaming, no defoamer can be used, the desulfurization system operates smoothly, and the running loss of amine liquid caused by foaming is reduced.
- Extend the service life of the filter. After removing the thermally stable salt to the control index, the corrosion rate will decrease, the corrosion products will be reduced, and the replacement cycle of the filter will be extended.
Through the operation of the sulfur recovery device system, the amine liquid online purification facility has achieved good results in removing thermally stable salts. Since the device was put into use, it has played a good role in enhancing the absorption of hydrogen sulfide by the amine liquid, the frequency of foaming of the amine liquid, and reducing the loss of the amine liquid, and good economic benefits have been achieved. At the same time, the equipment has a high degree of automation, which greatly reduces the labor intensity of workers. The technology is leading, the service cycle is long, and it has good use-value.
Bluslot provides customized service of wedge wire filter elements for amine filtration systems of sulfur recovery units.