Heat exchange system of low-heating-value gas boiler

By using a steam-heated flue gas system, the problems of ammonium bisulfate condensation and reheater overheating in low-calorific-value coal gas boilers under low-load operation have been solved. This has enabled corrosion prevention of the air preheater and flexible adjustment of the reheater, thereby improving the safety and economy of the equipment.

CN224434375UActive Publication Date: 2026-06-30HANGZHOU BOILER GRP CO LTD
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Patent Information

Application Number
CN202521387701.5
Authority / Receiving Office
CN · China
Patent Type
Utility models(China)
Current Assignee / Owner
Filing Date
2025-07-03
Publication Date
2026-06-30
Estimated Expiration
2035-07-03

AI Technical Summary

Technical Problem

When low-calorific-value gas boilers are operating at low loads, the condensation of ammonium bisulfate in the liquid phase leads to blockage and corrosion of the air preheater, and there is a high risk of overheating in the reheater, affecting the safety and economy of the unit.

Method used

A steam-heated flue gas system is adopted, which connects the low-temperature reheater and the high-temperature reheater through a steam flue gas heat exchanger to regulate the reheat steam temperature, reduce the risk of ammonium bisulfate condensation, and regulate the flue gas temperature through a bypass flue to improve the flexibility of the reheater.

Benefits of technology

This reduces the risk of ammonium bisulfate corrosion to the air preheater, extends equipment life, and reduces the risk of reheater overheating, thus improving the safety and economy of the unit.

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Abstract

The utility model discloses a low calorific value gas boiler heat exchange system which comprises a horizontal flue and a vertical flue, a high-temperature reheater and a low-temperature reheater are arranged in the horizontal flue, and an upper-stage air pre-heater and a lower-stage air pre-heater are arranged in the vertical flue. A left side connecting flue and a right side connecting flue are arranged on the left side and the right side of the middle position of the upper-stage air pre-heater and the lower-stage air pre-heater, a bypass flue is connected between the left side connecting flue and the right side connecting flue and provided with a steam flue gas heat exchanger, and the bypass flue is connected with the two ends of the flue gas heat exchange side of the steam flue gas heat exchanger. The two ends of the steam heat exchange side of the steam flue gas heat exchanger communicate with a steam bypass, and the steam bypass communicates with an outlet of the low-temperature reheater and an inlet of the high-temperature reheater. The smoke temperature of the lower-stage air pre-heater is increased, the possibility of condensation of the ammonium hydrogen sulfate is reduced, the corrosion risk of the ammonium hydrogen sulfate to the heating surface of the lower-stage air pre-heater is reduced, and the service life of equipment is remarkably prolonged; and the overtemperature risk of the reheater is reduced, and the flexibility of reheating steam temperature adjustment is improved.
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