大型循环流化床锅炉紧急补水泵新驱动技术的探讨

Discussion on new driving technology of emergency make-up water pump for large circulating fluidized bed boiler

为解决600MW等级超(超)临界循环流化床锅炉由于设置柴油机直接驱动紧急补水泵所造成的初投资高于1500万、系统复杂、使用概率低问题,保证锅炉在给水中断情况下受热面的安全,提出一种采用特种小汽轮机的新驱动技术,紧急补水泵由特种小汽轮机驱动,当发生全厂失电的情况,锅炉跳闸,利用锅炉的蓄热能力为补水泵提供动力。采取此驱动方式可大幅降低设备的投资费用,驱动设备仅为柴油机价格的30%,解决了设置紧急补水系统的固有矛盾;锅炉余压提供动力,不受外部动力电源及特殊燃料等因素的限制及影响,提高了可靠性。通过对锅炉工作在超临界状态及亚临界状态下的蓄热能力分别进行定量分析计算,采用特种小汽轮机的驱动方式是可行的,为循环流化床锅炉紧急补水系统的设置方案提供了一种可借鉴的思路。

In order to ensure the safety of the heating surface of the boiler in case of feedwater interruption,600MW ultra(ultra)critical circulating fluidized bed boilers are equipped with emergency water make-up system driven by diesel engine.However,the initial investment of this scheme is at least 15 million yuan.The system is complex,and the probability of emergency use is very low.It is precisely because of the inherent contradiction between its high investment and extremely low utilization rate that whether to equip the emergency make-up water system on the ultra(ultra)critical CFB Unit has always been the focus of controversy in the industry.Therefore,this paper proposes to adopt the new driving technology of special small steam turbine.The emergency make-up water pump is driven by special small steam turbine.In case of power loss of the whole plant,the boiler trips,the heat storage capacity of the boiler is used to provide power for the make-up pump.Adopting this driving mode can greatly reduce the investment cost of the equipment.The driving equipment is only 30%of the price of the diesel engine,which solves the inherent contradiction of setting the emergency water replenishment system.The reliability of the boiler is not affected by special factors such as residual pressure and external power.Through the quantitative analysis and calculation of the heat storage capacity of the boiler working in supercritical state and subcritical state,it is feasible to adopt the driving mode of special small steam turbine,which provides a reference idea for the setting scheme of emergency water make-up system of circulating fluidized bed boiler.