Waste oil recycling

Recycling of Waste Lubricant Oil

Capacity:

The waste oil recycling system is invested in two phases: phase 1 has a capacity of 1 ton/day, and phase 2 increases the capacity to 2 tons/day.

Technological Process:

The waste lubricant oil recycling process is shown in

Introduction of the Waste Lubricant Oil Recycling System
The HV-Distillation technology has been assembled at the Thanh Tung 2 Recycling Plant:

HV-Distillation is a deep vacuum distillation technology used to recycle waste lubricant oil into high-quality base oil. It is currently the most advanced technique, fully meeting Vietnam's national technical regulations for waste oil recycling (QCVN:2013/BTNMT) as well as various international environmental standards.
HV-Distillation is a third-generation waste oil recycling technology offering outstanding advantages such as:

Low investment cost
High recovery efficiency
High product quality
Compliance with the latest technical standards for waste oil recycling

This technology can recycle all types of waste lubricant oil (except PCB-contaminated oil) into base oil with a quality equivalent to that of virgin base oil, which can be used to formulate high-quality lubricants. The base oil recovery efficiency reaches 80%.

1. TECHNOLOGY DESCRIPTION

The recycling process of waste lubricant oil using HV-Distillation includes four main stages:

Stage 1: Water and impurity removal by coagulation
The collected waste oil is pumped into a coagulation reaction tank and heated to 80°C. Here, chemical reactions cause the impurities in the waste oil to coagulate, making separation easier.
After the coagulation reaction, the waste oil is pumped into vertical settling tanks to separate impurities such as sludge and water. This process lasts at least 48 hours.

Stage 2: Distillation to separate light fractions (gasoline and diesel)
After settling, the pretreated oil is pumped into a distillation unit to separate light fractions such as gasoline and diesel at temperatures up to 280°C and under vacuum pressure of about 60–65 cmHg.

Stage 3: Deep vacuum distillation to recover base oil
Following the separation of light fractions, the vacuum pressure is increased to 74–76 cmHg, and the temperature is gradually raised to 360–370°C. Base oil is recovered at this stage, typically SN300, or it can be separated into SN150 and SN500 depending on the process requirements.

Stage 4: Odor and color treatment for the base oil product
Base oil recovered from the distillation process often has odor and poor oxidation stability. Therefore, it must be deodorized using steam stripping and improved for oxidation resistance by filtering through activated clay (bentonite). The treated base oil is then pumped into storage tanks for sale or blending into lubricating products.

2. MATERIAL BALANCE

The material balance of the waste oil regeneration process depends largely on the source of the waste lubricant and the amount of impurities present.
The material balance, based on waste oil that has been pretreated by the coagulation method, is presented in the following table:

Input Material	Efficiency, %
Used Lubricating Oil	100

Product	Yield, %
Light gas, gasoline, and diesel	8–10
Base oil (SN 150 and SN 400/500)	75–80
Distillation residue	15–17

Chemical	Content, %
Coagulation chemicals	0.3–0.5
Activated clay	3–5

3. PROPERTIES OF RAW MATERIALS AND PRODUCTS

The waste oil regeneration technology using HV-Distillation is designed to produce high-quality products, ensure a high base oil recovery rate, and minimize environmental impact.

3.1. Properties of Waste Lubricant Oil

Component	%wt
Water and light gases	5–10
Diesel oil	5–7
Base oil	70–75
Residue	15–17

3.2. Base Oil Products

The base oil products include two types:

Light base oil: SN 150
Heavy base oil: SN 400/500

3.2.1. The properties of the products are presented in the following table:

Technical Specification	Light Base Oil (SN-150)	Heavy Base Oil (SN-400/500)
Specific Gravity @ 15°C	0.870	0.890
Viscosity, cSt at 40°C	25–35	80–95
Color	2.0	3.0
TAN, mg KOH/g	0.03	0.05
Viscosity Index	95	95
CCR, %wt	0.05	0.01
Flash Point (COC), °C	180 min	220 min
Metal Content, ppm	Negligible	Negligible

3.2.2. Inorganic Hazardous Components

Table 1: Inorganic Hazardous Components

No.	Hazardous Component	Unit	Maximum Allowable Value
1	Cadmium (Cd)	mg/l	0.5
2	Lead (Pb)	mg/l	15
3	Zinc (Zn)	mg/l	250
4	Nickel (Ni)	mg/l	70
5	Chromium VI (Cr VI)	mg/l	5

3.2.3. Hazardous Organic Components
Table 2: Hazardous Organic Components

TT	Thành phần nguy hại	Đơn vị	Giá trị tối đa cho phép
I. Hydrocarbon thơm
1	Benzen (Benzene), C₆H₆	mg/l	0,5
2	Ethyl benzen (Ethyl benzene), C₆H₅C₂H₅	mg/l	400
3	Toluen (Toluene), C₆H₅CH₃	mg/l	1.000
4	Xylen - các đồng phân (tổng nồng độ o-, m-, p-xylene), C₆H₄(CH₃)₂	mg/l	1.000
II. Hydrocarbon thơm đa vòng (PAH)
5	Antraxen (Anthracene), C₁₄H₁₀	mg/l	5
6	Axenapten (Acenaphthene), C₁₂H₁₀	mg/l	200
7	Benzo(k)fluoranthen (Benzo(k)fluoranthene), C₂₀H₁₂	mg/l	5
8	Benzo(a)pyren (Benzo(a)pyrene), C₂₀H₁₂	mg/l	5
9	Naphtalen (Naphthalene), C₁₀H₈	mg/l	50
III. PCB
10	PCB (Tổng tất cả đồng phân PCB hoặc tất cả Aroclor)	mg/l	0.25
102a	2,3,7,8-TCDD, C₁₂H₄Cl₄O₂	mg/l	0.005
102b	1,2,3,7,8-PeCDD, C₁₂H₃Cl₅O₂	mg/l	0.005
102c	1,2,3,4,7,8-HxCDD, C₁₂H₂Cl₆O₂	mg/l	0.05
102d	1,2,3,6,7,8-HxCDD, C₁₂H₂Cl₆O₂	mg/l	0.05
IV. Hợp chất hữu cơ khác
11	Pentaclorobenzen (Pentachlorobenzene), C₆HCl₅	mg/l	3

3.2.4. Other Components
Table 3: Other Components

No.	Component	Unit	Maximum Permissible Value
1	Solid impurities	%	6
2	Water in oil	%	0.01

3.3. By-products
The by-products of the regeneration technology are of two types: Diesel and Distillation Residue.

3.3.1. DIESEL Oil

Technical Specification	Value
Specific gravity @ 15°C	0.86
Viscosity, cst at 40°C	3 – 5
TAN, mgKOH/g	0.05
Flash point (open cup), °C	70
LHV, Kcal/Kg	10,000
Cetane index	50

This Diesel product fully meets the quality standards for use in diesel engines or as fuel oil.

3.3.2. Distillation Residue

Technical Specification	Value
Specific gravity @ 15°C	0.9 – 1.0
Viscosity, cst at 50°C, max	380
Ash content, % wt max	5
Softening point, °C	15 – 20

The Distillation Residue product can be used as a fuel, such as FO oil.

ENVIRONMENT
The waste sources generated during the used oil recycling process include two sources: exhaust gases from the recycling process and oil residues from the settling and separation process in the settling tank after condensation.

4.1. Exhaust Gas Treatment
The exhaust gases from the recycling process mainly contain VOCs and H2S. This exhaust gas is recovered from the discharge end of the vacuum system and passed through a FeCl3 solution tank with a pH of 4-4.5 to reduce H2S to sulfur powder (S).

Afterward, this gas mixture is directed to the flare gas system to completely burn the remaining VOC compounds in the exhaust gas.

The characteristics of the gas source after treatment fully comply with the exhaust gas standards as required by the regulations on managing exhaust emissions from used oil recycling activities.

Table 4. Maximum allowable values for pollutants in exhaust gas from used oil recycling activities

No.	Pollution Parameter	Unit	Maximum Permissible Value
1	Total dust	mg/Nm³	150
2	Carbon monoxide, CO	mg/Nm³	1,000
3	Sulfur dioxide, SO₂	mg/Nm³	500
4	Nitrogen oxides, NOₓ (as NO₂)	mg/Nm³	600
5	Hydrogen sulfide, H₂S	mg/Nm³	10
6	Total hydrocarbons, HC	mg/Nm³	100

4.2. Oil Residue from Settling Tank
The oil residue from the settling tank contains approximately 2-5% of the waste oil. Its main components include sludge oil, water, and other mechanical impurities. The final amount of sludge oil is collected after each system cleaning and then sent to the incinerator system for complete destruction. Thus, the used oil recycling process is entirely closed-loop, with no waste released.

4.3. Wastewater
The recycling process generates a small amount of wastewater, which is collected into an oil separation tank to recover the oil, then directed to the plant's central treatment tank.