x
Send Your Inquiry Today
Quick Quote

Depamu Plunger Pump Application for Coal-to-oil, gas and chemicals in CNPC

By / Apr 28, 2026

High-Pressure Precision: The Application of Depamu Plunger Pumps in CNPC’s Coal-to-Liquid, Gas, and Chemical

Abstract

The coal-to-chemicals industry, particularly Coal-to-Liquid (CTL) and Coal-to-Gas (CTG), represents a strategic pillar for nations rich in coal but dependent on oil imports, such as China. Within the operational framework of the China National Petroleum Corporation (CNPC), the conversion of solid coal into liquid fuels (diesel, naphtha) or chemical feedstocks (olefins, methanol) requires extreme physical regimes: high temperature, abrasive slurries, explosive hydrogen, and viscous intermediates. At the heart of these processes lies the high-pressure plunger pump. This paper explores the critical application of Depamu (Hangzhou) Pumps Technology Co., Ltd. plunger pumps within CNPC’s coal chemical value chain. It analyzes the engineering requirements of CTL processes, the technical parameters of Depamu’s equipment, comparative advantages over international competitors (LEWA, Milton Roy), and the economic impact of import substitution in state-owned energy giants.

1. Introduction: The Strategic Shift to Coal Chemistry

The global energy landscape is defined by the transition from fossil fuels, yet the demand for liquid hydrocarbons and chemical building blocks remains robust. For CNPC, which traditionally focused on upstream oil extraction, the diversification into Coal-to-Liquids is a matter of energy security. China’s "energy quadrilateral" (coal, oil, gas, renewables) heavily favors coal reserves .

The coal-to-chemicals process is notoriously punishing on rotating equipment. The Fischer-Tropsch (F-T) synthesis, the primary method for CTL, requires the precise injection of catalysts, the circulation of slurries, and the boosting of synthesis gas (Syngas) to pressures exceeding 100 bar . Previously, this segment was dominated by German and Japanese heavyweights. However, the rise of Depamu (Hangzhou) Pumps Technology Co., Ltd.—a certified API 674 manufacturer—has disrupted this dominance .

This article investigates how Depamu’s plunger and Metering Pump technologies solve the specific pain points of CNPC’s coal chemical divisions, focusing on the transition from "Made in China" to "Engineered in China" .

2. The Engineering Challenge: CNPC’s CTL Process Demands

To understand the application of Depamu pumps, one must first understand the hostile environment of a CTL plant.

  • Abrasive Slurries: In the first stage, coal is ground, mixed with a solvent and a catalyst (typically iron or cobalt-based) to form a coal-oil slurry. This mixture is non-Newtonian, highly viscous, and contains micron-level hard particles.

  • High-Temperature & High-Pressure (HT/HP): The gasification and syngas cleaning stages operate at high pressures (40–100 bar) and temperatures up to 300°C.

  • Hydrogenation (Hydrocracking): To upgrade the F-T wax to synthetic crude, the process requires hydrogen at extreme pressures. Depamu’s high-pressure往复泵 are used for hydrogenation feeding, where any leak of hydrogen-rich gas is a safety hazard.

  • Corrosion: The presence of hydrogen sulfide (H₂S) and carbon dioxide (CO₂) in sour gas requires pump metallurgy resistant to sulfide stress corrosion cracking (SSCC).

CNPC requires pumps that offer zero-leakage, pulsation control, and continuous operation for >8,000 hours. This is where Depamu’s plunger and diaphragm technologies intersect .

3. Depamu’s Technical Arsenal: Product Portfolio for CNPC

Depamu (杭州) has focused on reverse-engineering and improving upon German Hydraulic Diaphragm Metering Pumps from the 1990s . For CNPC’s coal chemical projects, the company deploys two primary product lines, often configured in API 675 (Metering) and API 674 (Reciprocating) standards .

3.1 High-Pressure Reciprocating Plunger Pumps

For the heavy lifting of coal slurry transportation and syngas boosting, Depamu utilizes the three-cylinder and five-cylinder plunger pumps.

  • Pressure Capability: Up to 350 MPa (50,000 PSI) .

  • Flow Rate: Capacities exceeding 100 m³/h.

  • Key Feature: Double helical gear transmission. Unlike worm gears that generate high heat and friction, Depamu’s helical gears offer high efficiency (up to 95%) and low noise, critical for long-term reliability in dirty environments .

  • Application at CNPC: Slurry feed to gasifiers. The pump must overcome the pressure drop of the gasifier vessel while pushing a solid-liquid mixture. The hardened plunger surface and packed plunger seals (or labyrinth packing) are engineered to resist the abrasive wear of coal particles .

3.2 Hydraulic Diaphragm & Plunger Metering Pumps (API 675)

For chemical dosing where zero atmospheric pollution is mandatory, Depamu supplies the DP(M)DA series .

  • Precision: Metering accuracy of ±0.5% (10%-100% stroke adjustment) .

  • Leak-proof Design: For dangerous media like hydrogen or amine solutions (CO₂ removal), Depamu utilizes hydraulically actuated diaphragms. The diaphragm isolates the process fluid from the plunger, ensuring zero leakage to the environment .

  • Material Science: Using duplex stainless steel, Hastelloy C, or 316L for pump heads to resist corrosion .

4. Case Study in Application: The "Import Substitution" Model

The core narrative for CNPC’s adoption of Depamu is not just local manufacturing policy—it is operational efficiency.

4.1 The 2016 Breakthrough

Historically, CNPC and Sinopec relied on German imports for high-temperature, high-pressure Reciprocating Pumps used in residue hydrotreating and coal-to-chemical processes. A German import unit typically cost over 10 million RMB (~$1.4M USD) with a delivery lead time of 24 months .

In 2016, a major project (Sinopec Zhenhai Refining & Chemical) required a "High Temperature and High Pressure Reciprocating Pump" for a coal-to-hydrogen project. Depamu took the challenge.

  • Outcome: After five years of R&D (culminating in 2021), Depamu delivered a domestically produced unit at half the price (approx. 5 million RMB) and a lead time of 8 months .

  • Performance: The pump met or exceeded the German specifications in terms of flow stability and packing life, marking the "zero breakthrough" for domestic reciprocating pumps in high-stakes oil refining and coal chemical processes .

4.2 Shenhua Ningxia Coal Industry Group (CNPC Affiliated Projects)

While CNPC is the primary focus, the spillover effect is visible in associated bids. In the Shenhua Ningxia Coal Chemical Complex (a peer in the state-owned sector), Depamu won bids for metering pumps for Polypropylene units (Project CSIE15022386) .

  • The Application: Depamu provided metering pumps for the propylene unit. Propylene injection requires high viscosity pumping and precise flow linearity. Depamu beat大连里瓦 (Dalian Liva—a JV of a German brand) to secure the contract, proving that their technology is trusted for the final chemical synthesis stage, not just the dirty front end .

5. Technical Analysis: Why Depamu Fits CNPC’s CTL Strategy

Focusing strictly on engineering, the Depamu plunger pump offers distinct advantages specific to coal chemistry.

5.1 Handling High Viscosity and Shear-Sensitive Fluids

In CTL, the "wax" created by the Fischer-Tropsch process is highly viscous when cooled. For chemical injection, Depamu employs double-ball check valves and specific valve spring designs optimized for 1,000+ cP fluids, preventing cavitation and valve "floating" . Furthermore, the low shear rate of the plunger pump (as opposed to centrifugal pumps) ensures that the polymer additives or catalysts are not mechanically destroyed during transfer.

5.2 Thermal Management

CTL processes run hot. Depamu pumps utilize an oil-immersed lubrication system for the power end, ensuring the crankshaft and crosshead remain cool even when pumping 300°C media. The isolation of the power end from the process end via a plunger packing or diaphragm barrier allows for thermal expansion without seizing .

5.3 Sealing Technology (The Abrasion Problem)

This is the critical differentiator. Coal slurry acts like liquid sandpaper. Traditional seals fail rapidly.

  • Depamu’s Solution: They utilize specialized stuffing box designs with high-pressure flush plans (API 675 compliance). The plungers are coated with ceramic or hard chrome plating, and the packing rings are often reinforced with carbon fibers or PTFE with anti-extrusion rings . This extends the Mean Time Between Maintenance (MTBM) to match international standards.

6. Economic Impact: Localization of the Supply Chain

For CNPC, the depreciation of the RMB or geopolitical tensions with Europe used to pose a risk to spare parts availability for German pumps. Depamu offers a fully localized supply chain .

  • Cost Per Unit: As noted, the cost reduction is roughly 40-50% compared to imported equivalents.

  • Service Time: A CNPC engineer in Xinjiang can receive a replacement plunger or check valve from Depamu’s Hangzhou warehouse within 72 hours, versus 6 weeks from Europe.

  • Strategic Partnership: Depamu is officially listed as a "long-term strategic cooperation partner" of CNPC, signifying that their engineering standards (ISO 9001:2000, CE, and API) have passed CNPC’s rigorous vendor audits .

7. Future Roadmap: Hydrogen and Supercritical CO₂

Looking ahead, CNPC is investing heavily in Underground Coal Gasification (UCG) and Green Hydrogen blending with coal gas. Depamu is already aligning its R&D.

The company is developing Cryogenic Pumps and Supercritical Fluid Equipment . For coal-to-chemicals, future applications include:

  1. Supercritical CO₂ Injection: Pumping CO₂ from the CTL plant back into depleted oil wells for Enhanced Oil Recovery (EOR)—a key CNPC focus.

  2. High-Pressure Hydrogen: Compressing hydrogen via plunger pumps for hydrocracking units.

8. Conclusion

The application of Depamu plunger pumps in CNPC’s coal-to-oil, gas, and chemical sectors represents a successful shift from technological dependence to self-sufficiency. By mastering the "German core" of hydraulic and mechanical engineering and innovating for local harsh conditions (abrasives, high pressures), Depamu has solved the fluid transportation challenge that bottlenecks CTL efficiency.

For CNPC, the adoption of Depamu is not merely a procurement decision; it is a strategic enabler. It reduces capital expenditure (CAPEX), secures the supply chain against geopolitical volatility, and ensures that the "black coal" is transformed into "golden chemicals" with maximum uptime.

As China continues to optimize its energy mix, the sync between CNPC's process engineering and Depamu's pump technology will serve as the global benchmark for high-pressure coal chemical processing.