Description:
FIELD OF THE INVENTION
The present invention relates to steam generation and thermal power plant technologies. More particularly, it concerns a Ring-shaped annular steam drum system with a non-uniform diameter profile and an integrated multi-zone phase separation mechanism designed for efficient steam-water separation in high-performance water tube boiler systems. The invention is compatible with both conventional and advanced compact boiler architectures, including vertical and spiral cascade combustion systems.

BACKGROUND OF THE INVENTION
Steam drums are critical components in water tube boilers, serving as the primary separation vessel for saturated steam and water mixtures. Conventional cylindrical steam drums rely on vertical or horizontal separation flow and typically integrate demisters, baffles, and down comers to perform gravity-based phase separation. However, these designs are increasingly challenged by modern boiler configurations that demand compactness, multi-zone operation, fuel flexibility, and enhanced thermal efficiency.
Existing drum designs also face limitations in optimizing steam quality in constrained layouts or spiral-type vertical combustion systems. Moreover, standard cylindrical drums require significant horizontal or vertical space, limiting their integration in systems with centralized fuel tanks or annular flue paths. Steam separation efficiency also suffers under high flow rates or when dealing with variable load conditions, often necessitating bulky external separators.
There is therefore a pressing need for a next-generation steam drum design that delivers high-efficiency phase separation, offers modular integration, and can be seamlessly adapted to modern, vertically stacked or annular combustion systems, while preserving or enhancing steam purity and flow control.

SUMMARY OF THE INVENTION
The present invention provides an annular steam drum system featuring a variable-radius geometry and a multi-stage internal separation mechanism designed to achieve superior steam quality and integration flexibility in both conventional and novel boiler architectures.
The drum is ring-shaped, allowing it to be positioned around a central element such as a vertical fuel tank, fed water tank, mud drum, etc, or integrated with standard water tube systems. The geometry includes a first zone with maximum diameter, which receives the incoming steam-water mixture tangentially, inducing a centrifugal swirl along the curved path of the annular shell. A wire mesh separator and gravitational settling mechanism assist in preliminary separation, directing heavier water droplets toward the base of the drum.
Separated water is collected via strategically placed down comers that return it to a lower mud drum. The upper zone of the drum comprises a demister section and inclined deflection plates that direct steam into a dryness enhancement zone before exiting through a tangentially placed steam outlet port, ensuring removal of 99.99% of water particles. The drum is enclosed within a thermally insulated cavity to shield mountings and control components from combustion zone heat, while auxiliary air and water jackets may use to maintain a safe operating temperature.
The drum may include a variable-diameter profile along its circumference, wherein the inlet is located at the lower zone of higher volume area to accommodate velocity reduction and enhanced separation, and the outlet is located at an upper zone of higher volume area to accelerate dry steam discharge.
This design significantly improves separation efficiency, reduces the need for bulky external separators, and allows for compact vertical system design. It is scalable, adaptable across a wide range of power plant sizes, and offers integration with multi-turbine configurations for improved system flexibility and reliability.

BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1: Three-dimensional cross-sectional view of the annular steam drum illustrating the structural configuration, including the tangential steam-water mixture inlet, feedwater inlet, chemical dosing port, blowdown outlet, and superheated steam outlet.
Figure 2: Cross-sectional front view showing central axis alignment of variable-radius annular shell; inclined base from point B (minimum radius) to point A (maximum radius); vertical and sloped internal baffles; 50% water level reference; wire mesh layer; demister unit; tangential steam-water mixture inlet at point A; steam outlet port near top of point A; mud drain port at lowest elevation at point A.
Figure 3: Top view of Multi-Zone Steam Separation in Annular Drum
• Figure 3a: Lower zone of annular steam drum; tangential steam-water mixture inlet at maximum radial diameter; angular swirl flow along inner curvature; inertia-based water separation; wire mesh droplet separator; gravitational down comers to mud drum; vertical partition wall between swirl and drying zones.
• Figure 3b: Upper drying zone; vertically mounted demister or chevron mist eliminator; inclined horizontal redirection platform; lateral dryness enhancement chamber; tangential steam outlet at top curvature; outlet angle optimized for minimal pressure drop and maximum dryness.
Figure 4: Front view illustrates the internal structure of the annular steam drum with variable-radius cross-section, showing: separation of lower inlet zone and upper outlet zone by a vertical partition wall; side view of vertically inclined demister mounted on an internal ramp and top curvature; angular positioning of inlet and outlet nozzles aligned tangentially to the flow path; steam-water mixture swirl flow path influenced by variable geometry and pressure gradient.
List of components with labels-
1. Ring-shaped annular steam drum
2. Dry Steam outlet
3. Steam mixture inlet
4. Down comer
5. Fed water inlet
6. Chemical fed inlet
7. Baffles
8. Wire mesh
9. Demister/chevron scrubber
10. Vertical wall
11. Inclined vanes (ramp)
12. Mesh span
13. Baffles inclined floor base
14. Natural slope structure base line
15. Hollow gap

DETAILED DESCRIPTION OF THE INVENTION
The steam drum (1) comprises a ring-shaped pressure vessel with a central void (15) to accommodate a fuel storage or mechanical structure. Steam-water mixture enters tangentially from inlet port (3) at the lower half, initiating a rotational flow. A curved wire mesh (8) intercepts the path as shown in figure 3a and 3b and enables droplets to coalesce and settle down due to inertia and gravity. As shown in figure 2, a bottom surface inclination (14) allows a natural flow of impurities or heavy particles from point ‘B’ (lower volume) to towards the down comer at point ‘A’ (higher volume) and settle down in to the mud drum through the down comer (4). Below the mesh zone, mud and heavier particles fall into a trench and exit through a water outlet. In figure 2, additional slope arrangements shown by offset (13) marked as baffles with inclined floor base position from point ‘B’ to point ‘A’ allowed a smooth and fast movement of collected impurities towards down comer.
The upper half contains a dry flow zone where the remaining moisture is removed using vertically arranged high-efficiency demister pads (9) or chevron mist eliminators. The steam then exits via outlet nozzles (2) mounted around the circumference. Steam purity above 99.95% is maintained under 10–100 bar pressure.
Blowdown and Water Conditioning Mechanism- In our design, a Continuous Blowdown (CBD) mechanism is integrated to actively discharge a controlled amount of water from the steam drum, thereby maintaining thermal balance and limiting the concentration of dissolved solids or contaminants that may accumulate during operation. This helps prevent scaling and enhances the longevity and efficiency of the system.
Fresh, preheated feedwater is introduced into the drum through a designated feedwater inlet port (5). This port is regulated to maintain the internal water level at approximately 50% of the total drum volume, ensuring adequate separation space for steam in the upper half. Additionally, a separate chemical dosing inlet port (6) is provided for introducing water treatment chemicals. These chemicals serve to inhibit scale formation, prevent corrosion, and optimize internal water chemistry for stable boiler operation.
The system optionally integrates a thermally insulated housing around the drum to isolate it from external heat sources. The annular structure enables modular turbine connections and retrofitting into existing water-tube systems.
 Detailed logical working of the annular steam drum can more understand with the help of the Figure 4, Partitioned front view of high-volume area.
Let’s divide the drum flow into three zones-
1. Lower zone- High Volume Entry Zone, at point A
2. Intermediate zone, Low Volume Intermediate Zone, at point B
3. Upper zone, High Volume Exit Zone, at point A
Lower zone- High Volume Entry Zone, at point A
• Steam-water mixture enters tangentially by an angle θt (tangent angle) into a large-diameter section.
• Due to the larger cross-sectional area, the flow decelerates (lower velocity).
• According to Bernoulli’s equation, if velocity decreases, static pressure increases.
• The increased pressure and reduced velocity allow:
o Heavier water droplets and impurities to lose momentum.
o Centrifugal swirl to push droplets outward.
o Wire mesh or curvature to facilitate gravitational separation downward.
Result: Ideal zone for coarse separation of liquid phase, bulk water and sedimentation.
Intermediate zone, Low Volume High Velocity Zone, at point B
• Steam flow enters a reduced-volume (narrower radius) region.
• Cross-sectional area decreases ⇒ Velocity increases (per continuity equation).
• Static pressure drops as dynamic pressure increases.
• This rapid acceleration helps:
o Shear remaining droplets, dislodging fine mist.
o Prevent back mixing.
o Direct steam efficiently toward the dryness enhancement zone.
Result: Acceleration zone assists in (mist breakup) scrubbing/removing residual moisture.
Upper zone, High Volume Exit Zone, again at point A
• Before exiting, steam enters a slightly re-expanded area and ready to shift in upper area (Dry zone).
• Velocity drops slightly again ⇒ allows controlled pressure stabilization.
• Demister pads and inclined guide vanes efficiently trap residual mist.
• Steam exits through the tangentially aligned outlet port at angle θt, which:
o Preserves residual swirl.
o Minimizes pressure drop.
o Ensures high dryness fraction.
Result: Final steam polishing zone; optimized for high dryness (~99.99%).

ADVANTAGES OF THE ANNULAR STEAM DRUM DESIGN
1. Space-Efficient Geometry– Annular (ring-shaped) form allows central integration of components (e.g., solid fuel tank, fed water tank), enabling compact, all-in-one boiler configurations without compromising steam separation performance.
2. Variable Radius Shell with Aligned Central Axis– Gradual change in radial cross-section induces natural flow stratification and pressure gradient, enhancing phase separation without additional cyclonic devices.
3. Gravity-Enhanced Separation Path– Inclined internal floor and varying shell depth allow water droplets and impurities to migrate naturally toward the mud zone for efficient removal.
4. Tangential Inlet with Swirl Stabilization– Steam-water mixture enters tangentially at the larger-radius zone, creating a controlled swirl that aids droplet inertia-based separation and minimizes flow turbulence at the outlet.
5. High Separation Efficiency– Combination of wire mesh, demister, baffles, and downward gravitational guidance enables up to 99.99% dry steam, protecting turbines and sensitive downstream equipment.
6. Dual-Zone Thermal Management– Vertical zoning (lower for steam-water mixture settling, upper for steam drying) improves thermal stratification and steam dryness without complex multi-chamber designs.
7. Broad Compatibility– Although customized for spiral cascade combustion systems, the annular drum is structurally and functionally compatible with traditional water tube boilers, offering retrofit potential.
8. Independent Mud Drum Integration– Dedicated mud collection and drainage design enhances boiler maintenance, minimizes blowdown frequency, and improves long-term operating reliability.
9. Reduced Risk of Flashback or Surging– Physical separation of inlet and outlet zones with curved flow path mitigates pressure surges and turbulence, ensuring stable steam output under varying load conditions.
10. Patentable Structural Innovation– No known commercial or published designs employ a variable-radius annular steam drum with axial symmetry and gravity-assisted phase separation—offering clear novelty and inventive step.
, Claims:Claim 1: An annular steam drum comprising a hollow ring-shaped shell with a non-uniform radial profile, having a first region with minimum diameter and a second region with maximum diameter, the curvature of the shell maintaining a common central axis at a uniform elevation, and configured to receive a tangential steam-water mixture inlet at the larger diameter region, thereby inducing natural swirl motion for centrifugal phase separation within the drum.

Claim 2: The steam drum of claim 1, wherein the internal base of the drum is designed with: (a) a naturally sloped floor extending from the region of smaller internal volume (minimum-diameter zone) to the region of larger internal volume (maximum-diameter zone), configured to facilitate gravitational settling of water-borne impurities and mud, and hydraulically connected to a mud drum via vertical down comer pipes; and,
(b) an additional internal sloped baffle floor ascending from the minimum-diameter region toward the maximum-diameter region, enhancing the natural segregation of heavier water and particulate matter without requiring external circulation systems.

Claim 3: The steam drum of claim 1, wherein the steam-water mixture enters through one or more tangential inlet nozzles that induce rotational flow within the annular path, enabling centrifugal separation without requiring external cyclone separators.

Claim 4: The steam drum of claim 1, wherein a wire mesh separator is positioned along the outer curved inner wall of the drum to intercept rotating steam flow, reduce velocity, and promote coalescence and gravitational settling of entrained water droplets containing solid impurities.

Claim 5: The steam drum of claim 1, wherein the annular shell is functionally segmented into a lower zone comprising staged separation devices, including inertial swirl path, wire mesh filters for water droplet collection and impurity settlement, and an upper zone comprising demisters pads or chevron scrubber to progressively dry the steam.

Claim 6: The steam drum of claim 1, wherein a plurality of demister pads or chevron scrubbers are mounted radially in a vertical orientation along the inner wall at the upper region and on inclined vanes (ramp) of the larger diameter zone, configured to remove residual moisture from the steam flow prior to outlet, ensuring steam dryness exceeding 99.99%.

Claim 7: The steam drum of claim 1, wherein the dry steam is extracted via a plurality of steam outlet nozzles circumferentially distributed in the upper outer region of the annular shell, such that steam flow is uniformly balanced and suitable for multiple turbine or process connections.

Claim 8: The steam drum of claim 1, wherein the structural geometry of non-uniform radial profile enables thermal balancing, optimized flow guidance, compact vertical installation, and compatibility with water-tube boiler configurations, including integration around internal heat sources, and such geometry being not previously disclosed in known cylindrical or spherical steam drums.