Tail Gas Treatment Unit

The tail gas treatment unit (TGTU) can purify the tail gas containing sulfide under the action of the catalyst. To achieve the purpose of removing harmful substances and making the exhaust gas discharged into the atmosphere meet environmental protection standards. TGTU and SRU equipment are commonly used in the sulfur recycled and tail gas treating sections of the petrochemical industry.

Ruichang tail gas treatment unit (TGTU)
Ruichang tail gas treatment unit (TGTU)

Why is Tail Gas Treatment Needed?

  1. Environmental reasons. Environmental problems are becoming more and more serious. In order to meet the requirements of environmental laws and regulations, enterprises such as petroleum refining and coke oven plants need TGTU to treat pollutants such as acid gases.
  2. Prevent downstream pollution. If the petrochemical industry does not properly deal with sulfur-containing compounds, it is easy to cause pollution problems in downstream sections.
  3. It can be translated into economic benefits. By converting acid gas into sulfur, it can be sold as an industrial raw material and obtain considerable economic income.
  4. Elemental sulfur has large market demand. Its transportation and storage are convenient, and it has a wide range of uses.

Ruichang Tail Gas Treatment Unit

Sulfur Recovery Unit (SRU) can convert sulfur-containing compounds in acid gas into elemental sulfur. However, the tail gas produced in the sulfur recovery process still retains at least 5% of sulfur-containing compounds. These exhaust gases are the objects to be treated by the tail gas treatment unit (TGTU). Tail gas treatment can maximize the conversion of sulfide in the tail gas to hydrogen sulfide, thereby effectively increasing the sulfur recovery rate to 99.9%.

TGTU Process

In order to further increase the sulfur conversion rate and make the tail gas meet environmental protection requirements, the tail gas of the Claus sulfur recovery unit needs to be subjected to hydrogenation reduction treatment, that is, enter the TGTU process.

TGTU Process
TGTU Process

Claus tail gas containing a certain amount of hydrogen sulfide and sulfur dioxide is heated (There are two heating methods, using the waste heat of the incinerator flue gas for heating and setting up an online heating boiler to generate high-temperature flue gas for direct mixing and heating) and enters the hydrogenation reactor. Under the action of a specific catalyst, a hydrogenation reaction is carried out to convert sulfur dioxide and other sulfides into hydrogen sulfide. The high-temperature reaction gas is cooled and sent to the absorption tower. In the absorption tower, hydrogen sulfide is absorbed and fixed by MDEA. The purified exhaust gas contains residual hydrogen sulfide. After the exhaust gas is burned in the exhaust gas incinerator, it is discharged into the atmosphere through the chimney. The rich amine liquid that has absorbed hydrogen sulfide is regenerated by the regeneration tower to release hydrogen sulfide and is returned to the Claus sulfur recovery unit for sulfur recovery.

The tail gas of the sulfur recovery unit is heated and mixed with hydrogen into the hydrogenation reactor, and the elemental sulfur and sulfur dioxide are reduced to hydrogen sulfide under the action of a catalyst. The reaction equations are as follows:

SO2 + 3H2 → H2S + 2H2O
SY + yH2 → yH2S

The hydrolysis reaction of carbon hydride sulfide and carbon disulfide also takes place in the hydrogenation reactor. The equations are as follows:

COS + H2O → H2S + CO2
CS2 + 2H2O → 2H2S + CO2

Ruichang Tail Gas Treatment Unit Features

Ruichang tail gas treatment unit uses ammonia desulfurization technology to treat acid tail gas, and it is used in conjunction with Claus sulfur recovery device to achieve better results. Compared with the traditional two-stage Claus + SCOT, three-stage Claus + SCOT, and Super Claus process, TGTU has the following advantages:

  • Tail gas treatment investment and operating costs are reduced by 40% compared with the SCOT process.
  • Ruichang TGTU device runs stably and is easy to operate. The equipment occupies a small area and the process flow is simple.
  • Ruichang TGTU process can produce ammonium sulfate as a by-product with a high recovery rate and higher economic benefits.
Process FlowClaus+Amine-based TGTUClaus+SCOT
Elemental Sulfur Recovery(%)≥96≥99.92
Total Sulfur Recovery(%)
(Including sulfur in ammonium sulfate)
Total Capital CostBase1.2×Base
Total RevenueBase0.9×Base
TGTU Capital CostBase1.4×Base
TGTU Operating CostBase1.4×Base
SO2 Emissions(mg/Nm3)≤35~400
Wastewater DischargeNoQuenching wastewater discharge
tail gas treatment process flow

Successful Cases of TGTU

Ruichang tail gas treatment unit (TGTU) can treat tail gas containing sulfur compounds (such as SO2). We can provide customers with SRU+TGTU standard process equipment, and can also design similar tail gas treatment processes according to customer needs.

NO.Client NameProject LocationScale
1Hebei new century energy technology co., ltd.Hebei ShijiazhuangSulfur recovery 10,000 t/a
2Ningbo keyuan plastic co., ltd.NingboSulfur recovery 30,000 t/a
3Weifang hongrun anxiliary agent co., ltd.WeifangSulfur recovery 150,000 t/a
4PetroChina hangzhou refineryHangzhouSulfur recovery 150,000 t/a
5PetrcChina hohhot pertrochemical companyHohhotSulfur recovery 3×130,000 t/a
6Guangdong jiasheng asphalt co., ltd.GuangzhouWaste liquid incineration tail gas 30,000Nm3/h
7Zhanjiang dongxing petroloum co., ltd.ZhanjiangSulfur recovery 5000 t/a
8Shenyang strait environment protection companyShenyangSulfur recovery 2×10,000 t/a+Waste liquid incineration tail gas 20,000Nm3/h
9Xianyang auxiliary agent plantXianyangWaste liquid incineration tail gas 22,000Nm3/h