Mining & Metallurgy - Flow Instrumentation Solution for the Steel Industry

Flow Instrumentation Solution for the Steel Industry

Application Description

Steel production follows two principal routes: the integrated route (sintering/coking → blast furnace → basic oxygen furnace → continuous casting → rolling) and the mini-mill route (direct reduction → electric arc furnace → rolling). Media cover process gases, steam, air, water and a range of oils. Heavy dust loading, high solids content, high viscosity, elevated temperature and corrosion are routine, placing stringent demands on the stability, accuracy and service life of flow instrumentation.

Measurement Characteristics by Medium

1. Blast furnace and converter gas: heavy dust loading and large line sizes (commonly > 1000 mm), prone to clogging and erosion.

2. Ammonia liquor, wastewater and slag-flushing water: contaminated with tar and solids; slag-flushing water approaches 100 °C and is alkaline-corrosive.

3. Benzene, rich oil and lean oil: high viscosity, with a tendency to crystallize and block.

4. Softened water (demineralized water): very low conductivity — its measurement bears directly on blast furnace cooling safety.

5. Hazardous media such as oxygen: low pressure loss, low leakage and explosion-proof construction required. Plant-wide instrumentation must run reliably over long periods and allow maintenance without removal.

Application Focus

Measurement difficulties in integrated steel plants concentrate in four duty classes: large-bore dust-laden gas, high-temperature high-solids slurry, high-viscosity crystallizing oil and low-pressure-loss hazardous gas — all calling for maintenance without disassembly. They are listed below by process stage.

1. Sintering and coking: dust in process gas, air and steam; tar in wastewater; benzene, rich oil and lean oil combine high viscosity with crystallization risk.

2. Blast furnace ironmaking: very low conductivity softened water tied directly to cooling safety; large-bore, dust-laden blast furnace gas; slag-flushing water near 100 °C carrying solids with alkaline corrosion.

3. BOF steelmaking: oxygen as a hazardous medium calls for low pressure loss, low leakage and explosion-proof design; lance cooling water is monitored by supply/return flow differential; converter gas lines exceed 1200 mm with severe dust erosion.

4. Continuous casting mold: primary and secondary cooling water must track strand section and steel grade precisely — the highest accuracy requirement anywhere in the process.

5. Rolling: high consumption of clean circulating, dirty circulating, laminar cooling and high-pressure descaling water, carrying mill scale and causing wear and scaling.

Solution Overview

Selection follows the medium: gas and steam use dirt-resistant differential pressure devices or vortex meters; water and slurry use electromagnetic meters; high-viscosity oils use wedge or Coriolis meters; hazardous media such as oxygen use throttling devices with low pressure loss and an integrally forged body.

1.Sintering and Coking

(1)Gaseous media: vortex flowmeters or dirt-resistant differential pressure flowmeters (V-cone, segmental orifice). Pressure tappings resist dust accumulation and the differential pressure signal stays strong, suiting long-term operation on dust-laden gas.

(2)Water and wastewater: electromagnetic flowmeters give an unobstructed straight-through bore with no restricting element; tar-bearing wastewater does not readily build up on the wall, so cleaning is rarely required.

(3)High-viscosity media: wedge flowmeters or Coriolis mass flowmeters. The wedge has no stagnant zone and resists crystallization blockage; Coriolis meters measure mass flow directly, unaffected by viscosity swings.

2. Blast Furnace Ironmaking

(1)Softened water cooling circuits: electromagnetic flowmeters have no obstructing parts and do not trap deposits. Conductivity after long-distance transfer through metallic pipework stays within measurable limits, safeguarding blast furnace cooling.

(2)Blast furnace gas (large bore, heavy dust): pipeline-type differential pressure flowmeters (standard orifice, multi-hole balanced orifice, V-cone, Venturi tube). High dirt tolerance and a strong differential pressure signal support long-term stable operation.

(3)Steam, compressed air and nitrogen: vortex flowmeters, sized precisely against operating parameters.

(4)Slag-flushing water (near 100 °C, solids-bearing, alkaline-corrosive): electromagnetic flowmeters with Hastelloy HC electrodes and NBR lining, combining abrasion and corrosion resistance.

3. BOF Steelmaking

(1)Oxygen (hazardous medium): Venturi tubes or multi-hole balanced orifice plates. Small obstruction area and low pressure loss (Venturi tube below 1 kPa); an integrally forged body reduces leakage risk, suiting explosion-proof duties such as oxygen and hydrogen.

(2)Lance recirculating cooling water: electromagnetic flowmeters track the supply/return flow differential to reflect cooling performance promptly, preventing lance burn-through and molten steel breakout.

(3)Bottom blowing (nitrogen, argon, CO₂): vortex flowmeters reach Class 0.5 and respond rapidly to control valve action, holding the bottom-blowing ratio steady to stabilise bath composition and temperature.

(4)Converter gas (line size > 1200 mm, dusty and abrasive): Venturi tubes, V-cone and segmental orifice throttling devices — dirt- and wear-resistant with stable output.

Continuous Casting Mold

Continuous casting imposes the highest flow measurement accuracy requirement in the plant. Cooling water flow directly determines strand solidification; deviation causes surface cracks, internal porosity and strand distortion. Primary and secondary water must track strand section and steel grade precisely, calling for Class 0.2 accuracy, high stability and fast response. MF series electromagnetic flowmeters meet the multi-strand measurement consistency and response requirements.

Rolling

Laminar cooling water controls the strip cooling path directly, determining metallurgical structure, mechanical properties and strip shape. Dirty circulating and high-pressure descaling water carry mill scale and cause marked wear and scaling, so liner and electrode materials must be verified against solids content and flow velocity. MF series electromagnetic flowmeters with abrasion-resistant liners and Hastelloy HC electrodes deliver stable metering on every circuit.

Customer Value

1. A complete flow instrumentation portfolio enables steel producers to achieve accurate, stable measurement across all process stages despite multiple media and severe duty.

(1)Fewer blockages, wear and crystallization faults; less dismantling, lower spare parts consumption and fewer unplanned shutdowns; greater equipment safety on critical units — blast furnace, BOF and caster.

(2)Stable gas and cooling water measurement underpins bottom-blowing ratio, strand cooling and laminar cooling control, cutting rejection rates for strand and plate while raising yield and the qualification rate of high-grade steels.

2. Dependable flow data supports plant-wide material balance, energy statistics, energy assessment and carbon accounting, advancing line digitalization and fine-grained cost control while improving recovery returns on by-product gases.