PREHEATING, OR ACCUMULATING PREHEATED, FEED-WATER FOR STEAM GENERATION; FEED-WATER SUPPLY FOR STEAM GENERATION; CONTROLLING WATER LEVEL FOR STEAM GENERATION; AUXILIARY DEVICES FOR PROMOTING WATER CIRCULATION WITHIN STEAM BOILERS

Introduced: September 1968

Classification Context

Section:: MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
Class:: STEAM GENERATION
Subclass:: PREHEATING, OR ACCUMULATING PREHEATED, FEED-WATER FOR STEAM GENERATION; FEED-WATER SUPPLY FOR STEAM GENERATION; CONTROLLING WATER LEVEL FOR STEAM GENERATION; AUXILIARY DEVICES FOR PROMOTING WATER CIRCULATION WITHIN STEAM BOILERS

Description

F22D covers the preheating, supply, and control systems for feed-water in steam generation plants, along with devices that enhance water circulation within boilers. This includes economizers and feed-water heaters that raise inlet water temperature before entry into the boiler, feed-water supply equipment and regulation systems, water-level control mechanisms, and internal circulation-promoting devices such as baffles or circulation tubes. The class encompasses both the thermodynamic efficiency improvements from preheating and the operational safety and stability features related to water management in steam boiler systems. Related auxiliary equipment for steam generation itself is classified elsewhere under F22B-F22C.

Filing statistics

IPC subclass F22D recorded 15,397 patent applications worldwide between 2013 and 2023. Annual filings grew from 894 in 2013 to 1,770 in 2023 (+98%), peaking at 2,004 applications in 2020. The most active applicants in class F22 are XIAN THERMAL POWER RESEARCH INSTITUTE COMPANY (922 applications), MIURA COMPANY (416 applications) and HARBIN BOILER COMPANY (390 applications).

Source: EPO PATSTAT, worldwide filings

Related Keywords

ACCUMULATOR(S) for preheated water in steam boilerspreheating, feeding or circulating feed-water in steam BOILER(S)ECONOMISERS in steam boilersFEEDWATER supply to steam boilersPREHEATING of feed-water for steam boilersfeedwater VESSEL(S) in steam boilers

5 direct subcodes

Child Classifications

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F22D 1/00 Feed-water heaters, e.g. preheaters
F22D 11/00 Feed-water supply not provided for in other main groups
F22D 3/00 Accumulators for preheated water
F22D 5/00 Controlling water feed or water level; Automatic water feeding or water-level regulators
F22D 7/00 Auxiliary devices for promoting water circulation

Top Applicants

Top 10 applicants by patent filingsfor class F22, 2013–2023, worldwide · Source: EPO PATSTAT

XIAN THERMAL POWER RESEARCH INSTITUTE COMPANY 922
MIURA COMPANY 416
HARBIN BOILER COMPANY 390
MITSUBISHI HITACHI POWER SYSTEMS 303
XIAN JIAOTONG UNIVERSITY 287
SGCC(STATE GRID CORPORATION OF CHINA) 257
HUADIAN ELECTRIC POWER RESEARCH INSTITUTE 253
SIEMENS DE 247
MIDEA 243
NORTH CHINA ELECTRIC POWER UNIVERSITY 223