Common structural forms of dry material sheds in biomass power plants

In recent years, with the rapid development of the biomass power generation industry, the design concept of biomass power plant combustion raw material storage site is constantly updated and changed. Considering economic rationality and higher and higher environmental protection requirements, the current biomass power plant The mainstream form of fuel storage is an off-site fuel storage station plus an on-site fuel storage area. The main buildings in the on-site fuel storage area include fuel warehouses, open storage yards, and semi-open storage yards (ie dry sheds, hereinafter referred to as dry coal sheds). ). The fire hazard of the fuel warehouse is classified as Category C. Due to the limitations of the design requirements for fire compartments, it is difficult to store fuel in a large area to meet the requirements of power plant operation in practical projects. Generally, it is not recommended to set up fire compartments. As China’s environmental protection requirements are becoming more and more stringent, it is difficult to meet the requirements of environmental protection acceptance and dust prevention unless wind and dust suppression measures are taken in the open storage yard. The dry material shed is designed in accordance with the specification requirements and the scale of the power plant according to the single storage capacity of not more than 20,000t. In the actual operation of the power plant, it can better meet the fuel storage and transportation functions, and the external wind and dust suppression net can also meet the environmental protection requirements, which is ideal. In-plant fuel storage area.

At present, the commonly used structural forms for the design of dry material sheds in biomass power plants are mainly portal rigid frame light steel structure workshops and single-layer bent structure workshops with concrete columns and steel roof trusses. These two types of dry material sheds have their own advantages and disadvantages in the construction and use process. Therefore, it is necessary to study the advantages, disadvantages and economics of dry material sheds with different structural forms under the same conditions, so as to provide a reference for choosing a scheme that is both economical and can meet the requirements of power plant operation and use in the design.

Project Overview

The dry material shed has three horizontal spans, each with a span of 36m and a span of 30m. The loader is used for loading. Considering that the transport machinery such as the loader and the superclass 20 heavy-duty truck can run smoothly in the shed area, the design adopts a 9m column spacing. The lower chord elevation of the roof truss is 9.000m, and the roof adopts a light steel structure roof with purlins and profiled steel plates. Basic wind pressure: 0.45kN/m2 (50a return period), 0.55kN/m2 (100a return period); basic snow pressure: 0.45kN/m2 (100a return period); roof live load: 0.50kN/ m2; Seismic fortification intensity: 7 degrees, the design earthquake is grouped into the first group, the design basic acceleration value is 0.10g, and the site category is Class III.

Structure selection comparison

(a)Comparison of Main Engineering Quantities of 12 Structural Systems

The design of this project is based on two structural systems of portal rigid frame light steel structure workshop and concrete column + steel roof truss single-story bent structure workshop. According to the above design conditions, PKPM structural design software (V5.3 version) is used for modeling and calculation, the two calculation models meet the same design control conditions as the benchmark.

From the calculation, it can be concluded that the 30-span dry-material shed roof system saves about 19% in the steel-gauge portal rigid frame form compared with the trapezoidal steel roof truss form. According to the data analysis, it can be concluded that the trapezoidal steel roof truss calculated according to the simply supported beam model is in the form of a truss due to the large bending moment at the mid-span, but the steel consumption is still higher than that of the portal rigid frame solid web roof calculated according to the continuous beam model. The amount of steel used in the beam is large. However, with the decrease of the span, the difference in the amount of steel used for the roof beams of the two structural forms also decreases.

The project cost of the plant column in this project does not control the cost of the entire project. The difference in the total cost of the columns between the two structural forms can be ignored compared to the total cost of the roof system. Therefore, comprehensive consideration, it can be concluded that the light steel structure workshop with portal rigid frame in this project is economically superior to the single-storey bent structure workshop using concrete column + steel roof truss.

(2)Performance Advantages and Disadvantages Comparison of 22 Architectures

The advantages of the concrete column + steel roof truss structure system: the concrete column has good durability and fire resistance, and no special maintenance is required within the design life of the workshop; the roof adopts a trapezoidal steel roof truss system, which can improve the overall rigidity of the workshop and is suitable for deformation control comparison. Strict workshops, such as dry sheds fed by grab cranes.

Disadvantages: The steel consumption of the trapezoidal steel roof truss and roof support system is larger than that of the portal rigid frame roof system, which increases the cost of the workshop; due to the height of the roof truss itself, the height of the workshop increases accordingly, which also increases the workshop. Compared with the portal rigid frame system, the construction of trapezoidal steel roof trusses is more difficult.

The advantages of the portal rigid frame structure system: are lightweight and less steel consumption, which can reduce the project cost; since the section of the solid web steel beam is simpler than that of the steel roof truss, the aesthetics of the workshop is better; because the height of the main steel beam itself is higher than that of steel The roof truss is small, which reduces the height of the factory building and saves the cost of the factory building; compared with the structural system of concrete column + steel roof truss, the construction is simple and fast.

Disadvantages: The durability and fire resistance of steel columns are worse than that of concrete columns, and fire-retardant coatings and anti-corrosion coatings need to be regularly maintained within the design service life; the overall rigidity of the roof of the portal frame system is poor.

The structural form of the biomass power plant dry shed should be selected based on economical and reasonable conditions, taking into account the requirements of the production process and operation and use. According to the return visit to the operating power plants, if the main raw materials are corrosive to a certain extent or the production and operation management is not strict, it is easy to cause damage to the dry material shed columns and other components, burying potential safety hazards. In view of this situation, it is recommended to use concrete columns or portal rigid frame columns to adopt concrete outsourcing protection measures to ensure that the structural members are not damaged or less damaged during the service life. If a grab crane is used for feeding, the height of the workshop will increase, and the overall deformation requirements of the workshop will be strict. Considering the economy, the general dry material shed is recommended to be designed according to the portal rigid frame structure workshop.