Basic overview of cogeneration

Introduction

Cogeneration, also known as combined heat and power (CHP), is a highly efficient system that not only generates electricity but also provides thermal energy to users. In this process, steam turbines are used to produce both electricity and heat, making it an ideal solution for areas with consistent thermal demand. The steam used in cogeneration typically comes from the exhaust of extraction steam turbines or back-pressure steam turbines, with pressure levels usually ranging between 0.78 to 1.28 MPa for industrial use and 0.12 to 0.25 MPa for residential heating. One of the key advantages of cogeneration is the absence of cold source losses, which allows thermal efficiency to reach up to 85%, far exceeding that of traditional condensing power plants, which typically operate at around 40%. This increased efficiency leads to significant energy savings, better environmental protection, and improved living conditions. However, cogeneration requires close coordination between power generation and heating systems, which can reduce operational flexibility and increase capital costs. Therefore, it is most effective when integrated into urban planning and centralized heating zones, where sufficient heat load guarantees optimal performance and maximum economic benefits.

Specific Requirements

Cogeneration systems work best when thermal power plants are located in proximity to industrial facilities and residential areas, ensuring efficient energy distribution and maximum economic returns. In many developed countries, especially in Western and Eastern Europe, cogeneration has reached a high level of development. Thermal power plants account for about 30% of total power generation capacity and are widely used for both industrial processes and district heating. Industries such as paper, steel, and chemicals (including petrochemicals) are major beneficiaries of cogeneration, as they not only consume large amounts of electricity but also generate waste gases like blast furnace gas, which can be utilized as fuel for cogeneration units. Urban industrial zones and densely populated areas are also prime candidates for cogeneration projects, but careful analysis of local heat demand is essential. The general heating coefficient should not be less than 0.5, meaning that industrial heat loads should be utilized for over 3,500 hours annually, and residential heating should last at least three months during winter. Additionally, the typical heating range of a cogeneration plant should not exceed 5 to 8 kilometers. Cogeneration also demands high-quality fuel, particularly in terms of sulfur and phosphorus content, and the location should be chosen downwind of the city's prevailing winds to minimize environmental pollution.

When excess steam is produced during cogeneration, it can be effectively managed using absorption chillers for air conditioning or domestic hot water supply. The steam generated by boilers can be directed through back-pressure or extraction steam turbines. Beyond meeting heating needs, this steam can also serve as the working fluid in absorption chillers to produce chilled water at 6–8°C for cooling applications in air conditioning or industrial processes.

BOD COD Sensor

Overview

BOD COD Sensor,Biochemical Oxygen Demand Sensor,BOD COD probe

Suzhou Delfino Environmental Technology Co., Ltd. , https://www.daruifuno.com