The invention discloses an in-boiler desulfurization and denitration
system and method for a chain grate boiler. The
system comprises the chain grate boiler, a feed bin and a
smoke and
powder mixer, wherein the feed bin is used for providing a space for containing a desulfurization agent and / or a denitration agent; the
smoke and
powder mixer is connected with the feed bin, a
flue gas pipeline and the chain grate boiler respectively;
flue gas is mixed with the desulfurization agent and the denitration agent in the
smoke and
powder mixer to provide power to deliver the desulfurization agent and the denitration agent to an injection pipeline component mounted in the chain grate boiler for injection; the desulfurization agent and the denitration agent are a
calcium-based desulfurization agent and
urea powder respectively. The desulfurization agent and the denitration agent are delivered into the chain grate boiler through the
tail flue gas of the boiler, so that the
urea powder can be effectively prevented from absorbing
moisture for agglomeration; in addition, compared with that of
hearth flue gas, the temperature and
oxygen content of the
tail flue gas are lower, so that an area of which the temperature is relatively proper and the
oxygen concentration is relatively lower can be provided for denitration reaction in a higher-temperature area of a
hearth, and the problems of instable
hearth temperature, small reaction space and the like of the chain grate boiler can be solved.