Ceramic Valves for Carbide Slag Slurry in Acetylene Generation

Dry and wet acetylene generation processes showing carbide slag slurry recovery, filtration and water recycling

KOWOV ceramic valves are used for carbide slag slurry and recycled process water in calcium carbide-based acetylene generation. This application overview focuses on generator water control, abrasive wear, scaling and valve sticking, with related slurry recovery and filter press operations. It includes a ceramic C-type valve case reference and the FCCV1, FCRV and FCCV6 product range

Calcium Carbide Slag Slurry

Calcium carbide slag slurry is widely present throughout calcium carbide-based acetylene production, including acetylene generation, gas scrubbing, purification, and acetylene recovery systems

Its highly abrasive and scaling-prone characteristics frequently cause valve erosion, internal buildup, sticking, and blockage, affecting continuous and reliable plant operation

Acetylene generation unit with calcium carbide slurry handling

Operating Conditions

Calcium Carbide Acetylene Generator

The primary reaction in a calcium carbide acetylene generator is:

CaC₂ + 2H₂O → C₂H₂ + Ca(OH)₂

In dry-process acetylene generators, water addition is controlled by metered spraying, while wet-process generators typically regulate water addition through liquid-level control. Clarified carbide slag liquor is often recycled as process water and may still contain suspended carbide slag particles

The suspended solids are abrasive and highly prone to scaling. They can erode valve internals and form hard deposits on valve and pipeline surfaces, resulting in internal leakage, increased operating torque, sticking, or failure to open

Operating Parameters

Item	Value	Item	Value
Medium	Clarified carbide slag liquor containing suspended solids	Phase	Liquid-solid two-phase flow
Operating Pressure	≤0.6 MPa	Nominal Pressure	PN16 / PN25
Differential Pressure	≤0.5 MPa	Nominal Diameter	DN25-DN125
Operating Temperature	<100°C	Thermal Conditions	No significant thermal shock
Characteristics	Abrasive and scaling-prone	Application	Isolation and flow control

Medium Details

Parameter	Recommended English
Chemical Composition	Calcium hydroxide [Ca(OH)₂], calcium carbonate (CaCO₃), residual carbide, and other suspended solids
Corrosive Components	Low concentrations of chloride ions may cause localized corrosion
Corrosivity / pH	Alkaline; actual pH to be confirmed by site analysis
Solids Content	To be confirmed by site data
Particle Size	To be confirmed by site data
Particle Hardness	To be confirmed by site data

Unique Operating Challenges

Localized Chemical Corrosion

Although the bulk medium may be only moderately corrosive, chloride ions can still cause localized corrosion of conventional metal components. Duplex stainless steel 2205 may be considered depending on the actual chloride concentration, temperature, and pH

Abrasive Erosion

Carbide slag slurry contains suspended carbide residue, iron-bearing particles, and other hard solids. These particles continuously erode valve flow passages and sealing surfaces, particularly in small-bore, high-velocity pipelines, resulting in internal leakage and premature valve failure

High Solids Content and Plugging

The slurry may have a high solids content and elevated apparent viscosity. Solids readily settle and accumulate in valve cavities, dead zones, and restricted flow passages, increasing operating torque and causing sticking or blockage

Crystallization and Hard Scale Formation

Calcium hydroxide in the medium can react with absorbed carbon dioxide to form calcium carbonate. These solids crystallize and accumulate as hard scale on valve and pipeline surfaces, gradually restricting the flow passage and preventing complete valve operation. The conversion of Ca(OH)₂ into precipitated CaCO₃ is a recognized carbonation process. arxiv.org

Equipment and Operational Risks

Abrasive particles erode sealing surfaces, reducing control accuracy and causing internal leakage. Frequent maintenance and valve replacement increase lifecycle costs
Crystallized deposits and hardened scale can obstruct valves and pipelines, causing valves to stick or fail to open. Manual cleaning is labor-intensive and results in extended production interruptions

Keywords: Chlor-Alkali Industry, Calcium Carbide, Acetylene Generator, Carbide Slag Slurry, Clarified Carbide Slag Liquor, Scaling, Crystallization, Ceramic C Valve, FCCV6, FCRV

Process Pain Points and Improvement Opportunities

Conventional Valve Materials and Types

Conventional solutions mainly include metal-seated ball valves and eccentric hemispherical valves. Some valve internals are protected with tungsten carbide coatings or polymer-based coatings to improve wear and corrosion resistance

Problems with Conventional Valves

Continuous slurry erosion damages the sealing surfaces and reduces control accuracy. Calcium-containing deposits crystallize and accumulate inside valve cavities, causing increased operating torque, sticking, and eventual failure to open or close

Cleaning Frequency and Service Life

Valves typically require cleaning every 3-4 months. After approximately 8-9 months of operation, erosion of the sealing surfaces frequently results in internal leakage and unstable flow control

Losses Caused by Shutdown Maintenance

The system must typically be shut down every three months for valve and pipeline cleaning. These frequent shutdowns interrupt continuous acetylene production, increase labor and maintenance costs, and create additional risks during system isolation, disassembly, cleaning, and restart

Scale removal and valve replacement also consume significant time and resources, reducing equipment availability and increasing the overall lifecycle cost of the system

Case Study

Selected End Users

Inner Mongolia Junzheng Chemical Co., Ltd., since 2020
Baotou Haipingmian High Polymer Industry Co., Ltd., since 2020
Inner Mongolia Yihua Chemical Co., Ltd., since 2022
Shandong Lutai Chemical Co., Ltd., since 2022
Inner Mongolia Shuangxin Environment-Friendly Material Co., Ltd., since 2022
Inner Mongolia Sanwei New Materials Co., Ltd., since 2024

Across calcium carbide-based acetylene production, including acetylene generators, carbide-slurry recovery and filter-press systems, valves commonly suffer from severe erosion, wear, crystallization, scaling and plugging. Conventional metal valves are therefore prone to seizure and internal or external leakage, requiring frequent removal, cleaning and maintenance. This increases operator workload and disrupts stable production

At one chlor-alkali plant, the water-control valve serving an acetylene generator was originally a conventional metal valve. The medium was clarified recycled water recovered from calcium carbide slurry. Calcium hydroxide in the water reacted with dissolved or entrained carbon dioxide to form calcium carbonate deposits on the piping and valve internals. The deposits repeatedly caused the valve to seize, preventing normal operation and destabilizing generator water control

The valve had to be removed frequently for cleaning. Even high-pressure water jetting was ineffective, and heat had to be applied to fracture the hardened deposits, substantially increasing maintenance time and workload

A KOWOV Ceramic C-Segment Ball Valve was subsequently installed. Since commissioning, the valve has operated without sticking. Inspection found no significant scale accumulation or other abnormalities on its internal surfaces. Following the successful trial, the customer began replacing conventional metal valves on additional acetylene-generator lines

No.	Item	Conventional Metal Valve	KOWOV Ceramic C-Segment Ball Valve
1	Valve design	Cam-Flex eccentric rotary valve	C-segment ball valve
2	Key wetted materials	Carbon steel / stainless steel	Structural ceramic
3	Shutoff class	Class IV	Class IV
4	Cleaning interval	Sticking after approximately two weeks; cleaning required monthly	Operated normally for three months without sticking
5	Cleaning time	Approximately two hours per event	No cleaning required during the reference period
6	Inspection result	Severe scale buildup	No significant scale buildup observed

Demonstrated Service Life: ≥3 Years

Ceramic valve installation shown in the carbide slag slurry application case

Scale deposits inside valves in carbide slag slurry service

Why Choose Ceramic Valves?

Superior Abrasion and Erosion Resistance

Structural ceramics have a Rockwell hardness of HRA 87 or higher, substantially exceeding that of conventional metal alloys and PTFE-lined components. They withstand continuous impact and scouring from hard particles in calcium carbide slurry, reducing internal wear, leakage and valve replacement frequency

Excellent Corrosion Resistance

Structural ceramics are inorganic, non-metallic materials with excellent chemical stability. Under applicable operating conditions, they resist corrosion from alkaline slurry, chloride-containing media and many acidic or alkaline process fluids commonly encountered in the chlor-alkali industry

Smooth Surface and Low Adhesion

Precision-ground ceramic surfaces have very low roughness and low material adhesion, helping to minimize calcium carbonate scaling and solids buildup. The high-hardness ceramic flow path also withstands continuous slurry erosion, ensuring smoother operation and more accurate flow control

Stable Sealing and Process Control

The combination of high mechanical strength, smooth ceramic surfaces and precision-lapped sealing components reduces scaling, wear and internal leakage. Ceramic ball valves and ceramic C-segment ball valves therefore provide more stable control, fewer maintenance interventions and improved batch-to-batch process consistency

Conclusion: Ceramic ball valves and ceramic C-segment ball valves provide a reliable solution for long-term operation in calcium carbide slurry systems, significantly reducing valve sticking, leakage and unplanned maintenance