Pabrik Asam Sulfat dari Gas Hasil Pembakaran dari Pulverized Coal-Fired Boiler Kapasitas 51.000 Ton/Tahun

Chantiq Hast Dhuatu, Nur Rofiqoh Eviana Putri, S.T., M.Eng., Ph.D.

2026 | Skripsi | TEKNIK KIMIA

Asam sulfat (H?SO?) merupakan salah satu bahan kimia dasar yang memiliki peranan penting dalam berbagai sektor industri, seperti industri pupuk, petrokimia, pengolahan logam, dan pengolahan air. Seiring meningkatnya kebutuhan asam sulfat di Indonesia, diperlukan pengembangan industri yang tidak hanya mampu memenuhi kebutuhan pasar, tetapi juga mendukung prinsip keberlanjutan dan pemanfaatan limbah industri. Pabrik asam sulfat 98% ini dirancang dengan memanfaatkan flue gas hasil pembakaran boiler dari PLTU Paiton Unit 7 dan Unit 8 sebagai bahan baku utama sehingga dapat meningkatkan nilai tambah limbah gas buang sekaligus mengurangi emisi yang dilepaskan ke lingkungan. 

Pabrik direncanakan berlokasi di Paiton, Kabupaten Probolinggo, Jawa Timur, dengan kapasitas produksi sebesar 51.000 ton/tahun dan beroperasi selama 24 jam per hari serta 330 hari per tahun. Bahan baku yang digunakan berupa flue gas dari PLTU Paiton Unit 7 dan Unit 8 sebanyak 33.802.861,77 ton/tahun. Proses produksi asam sulfat menggunakan teknologi Wet Sulfuric Acid (WSA), yang memungkinkan pemanfaatan senyawa sulfur yang terkandung dalam gas buang untuk menghasilkan asam sulfat bernilai ekonomis. Pada proses ini, gas umpan diolah melalui beberapa tahapan pemurnian dan konversi, kemudian senyawa sulfur dioksida dioksidasi menjadi sulfur trioksida di dalam Converter Reactor. Produk sulfur trioksida selanjutnya direaksikan dan dikondensasikan melalui tahapan proses WSA untuk menghasilkan asam sulfat dengan kemurnian 98%. 

Pemanfaatan flue gas sebagai bahan baku utama memberikan keuntungan berupa pengurangan kebutuhan bahan baku sulfur konvensional serta mendukung konsep industri berkelanjutan melalui integrasi dengan pembangkit listrik tenaga uap. Selain menghasilkan produk yang bernilai ekonomi tinggi, pabrik ini juga berpotensi mengurangi dampak lingkungan akibat emisi gas buang yang mengandung senyawa sulfur. Berdasarkan hasil perhitungan, pabrik ini membutuhkan Fixed Capital sebesar USD 46.747.172,31 dan Working Capital sebesar USD 2.734.765,93. Dengan kapasitas produksi 51.000 ton/tahun, pabrik menghasilkan pendapatan (sales) sebesar USD 18.418.359,31 per tahun, sementara total biaya produksi (manufacturing cost dan general expense) sebesar USD 15.932.094,55 per tahun, sehingga diperoleh laba sebelum pajak sebesar USD 2.486.264,76 per tahun dan laba setelah pajak sebesar USD 1.939.286,51 per tahun setelah dikenakan pajak penghasilan badan sebesar 22%. 

Indikator kelayakan investasi menunjukkan hasil yang belum memadai, dengan nilai Return on Investment (ROI) sebelum pajak sebesar 5,32?n setelah pajak sebesar 4,15%, jauh di bawah batas minimum 11% yang disyaratkan untuk kategori investasi berisiko rendah (low risk) menurut Aries dan Newton (1955). Periode pengembalian modal (Payout Time/POT) diperoleh sebesar 6,53 tahun sebelum pajak dan 7,07 tahun setelah pajak, melampaui batas maksimum 5 tahun untuk kategori low risk. Selain itu, nilai Discounted Cash Flow Rate of Return (DCFRR) sebesar 6,41% masih berada di bawah Minimum Acceptable Rate of Return (MARR) sebesar 15%, yang mengindikasikan bahwa tingkat pengembalian investasi pabrik belum cukup menarik apabila memperhitungkan nilai waktu uang. Hasil perhitungan Break Even Point (BEP) dan Shutdown Point (SDP) menunjukkan nilai sebesar 77,57?n 22,73% dari kapasitas produksi, yang berarti pabrik baru mencapai titik impas pada kapasitas operasi yang relatif tinggi, meskipun rentang antara BEP dan SDP yang cukup lebar tetap memberikan fleksibilitas operasi. Analisis sensitivitas terhadap DCFRR menunjukkan bahwa total cost dan sales merupakan variabel yang paling berpengaruh terhadap kelayakan ekonomi pabrik, diikuti oleh kapasitas produksi, sedangkan fixed capital memiliki pengaruh yang relatif kecil. 

Berdasarkan aspek teknis maupun ekonomi, pemanfaatan teknologi WSA dan integrasi dengan PLTU Paiton menunjukkan bahwa pabrik asam sulfat 98% berkapasitas 51.000 ton/tahun secara konvensional belum sepenuhnya memenuhi kriteria kelayakan finansial untuk kategori investasi berisiko rendah, terutama karena tingginya

Sulfuric acid (H?SO?) is one of the basic chemicals that plays an important role in various industrial sectors, such as the fertilizer, petrochemical, metal processing, and water treatment industries. As the demand for sulfuric acid in Indonesia continues to grow, it is necessary to develop an industry that is not only capable of meeting market demand but also supports the principle of sustainability and the utilization of industrial waste. This 98% sulfuric acid plant is designed to utilize flue gas from the combustion of boilers at PLTU Paiton Units 7 and 8 as the main raw material, thereby increasing the added value of waste flue gas while reducing emissions released into the environment. 

The plant is planned to be located in Paiton, Probolinggo Regency, East Java, with a production capacity of 51,000 tons/year and operating 24 hours a day for 330 days a year. The raw material used is flue gas from PLTU Paiton Units 7 and 8, amounting to 33,802,861.77 tons/year. The sulfuric acid production process uses Wet Sulfuric Acid (WSA) technology, which enables the utilization of sulfur compounds contained in the flue gas to produce economically valuable sulfuric acid. In this process, the feed gas is processed through several purification and conversion stages, after which the sulfur dioxide compound is oxidized into sulfur trioxide in the Converter Reactor. The sulfur trioxide product is then reacted and condensed through the WSA process stages to produce sulfuric acid with a purity of 98%. 

The utilization of flue gas as the main raw material provides the advantage of reducing the need for conventional sulfur raw material and supports the concept of sustainable industry through integration with a coal-fired steam power plant. In addition to producing a product with high economic value, this plant also has the potential to reduce environmental impact caused by flue gas emissions containing sulfur compounds. To support the feasibility of establishing the plant, an economic evaluation was also conducted, covering investment requirements, production costs, profitability, and financial feasibility indicators. Based on the calculation results, this plant requires a Fixed Capital of USD 46,747,172.31 and a Working Capital of USD 2,734,765.93. With a production capacity of 51,000 tons/year, the plant generates sales revenue of USD 18,418,359.31 per year, while the total production cost (manufacturing cost and general expense) amounts to USD 15,932,094.55 per year, resulting in a profit before tax of USD 2,486,264.76 per year and a profit after tax of USD 1,939,286.51 per year after applying a corporate income tax rate of 22%. 

The investment feasibility indicators show results that are not yet adequate, with a Return on Investment (ROI) before tax of 5.32% and after tax of 4.15%, far below the minimum threshold of 11% required for a low-risk investment category according to Aries and Newton (1955). The Payout Time (POT) was found to be 6.53 years before tax and 7.07 years after tax, exceeding the maximum limit of 5 years for the low-risk category. In addition, the Discounted Cash Flow Rate of Return (DCFRR) of 6.41% is still below the Minimum Acceptable Rate of Return (MARR) of 15%, indicating that the plant's investment return is not yet sufficiently attractive when accounting for the time value of money. The calculation results for the Break Even Point (BEP) and Shutdown Point (SDP) show values of 77.57% and 22.73% of production capacity, respectively, meaning that the plant only reaches the break-even condition at a relatively high level of operating capacity, although the fairly wide range between the BEP and SDP still provides operational flexibility. Sensitivity analysis on the DCFRR shows that total cost and sales are the variables with the greatest influence on the plant's economic feasibility, followed by production capacity, while fixed capital has a relatively small influence. 

From both a technical and economic standpoint, the utilization of WSA technology and integration with PLTU Paiton shows that the 98% sulfuric acid plant with a capacity of 51,000 tons/year does not yet conventionally meet the financial feasibility criteria for a low-risk investment category, mainly because the high investment in process and utility equipment is not yet proportional to the scale of sales obtained. Nevertheless, this plant has strategic value that is not fully reflected in its profitability figures, namely the environmental fee benefit for PLTU and its contribution to resource efficiency and the implementation of the green industry concept in Indonesia, making it still worth further study as a mutually beneficial cooperation opportunity between the plant and PLTU Paiton.

Kata Kunci : Asam sulfat 98%, Wet Sulfuric Acid (WSA), flue gas, PLTU Paiton, kelayakan ekonomi.