Integral Grating Plate

Product Model	注塑格栅板系列
Category	PP Molded Products
Reference Price	Price on request

Hot Customizable for Working Conditions 11 Technical Parameters

Product Overview

Integral grating plates are plastic support components used internally in spray towers, washing towers, and absorption towers to bear the packing layer. The grating plates are laid on the supporting rings inside the tower, with loose bulk fillers such as Raschig rings and multi-sphere packing placed on top, while gas-liquid channels are left below. They not only bear the weight of the packing and liquid hold-up but also allow gas to pass upward and liquid to flow downward uniformly, making them a key internal component of packed towers.

Traditional grating plates are often made of PP strips cut and welded manually, which is time-consuming, has many weld seams, and exhibits uneven hole openings. Integral grating plates are made of flame-retardant PP through injection molding in one piece. The grating holes on the plate surface are arranged regularly, with high and consistent hole opening rates. The plates are assembled together using clips or overlapping joints, eliminating the need for on-site welding, saving labor, and shortening the equipment manufacturing cycle.

The integral grating plates supplied by Xicheng Environmental Protection are made of flame-retardant materials, corrosion-resistant, lightweight, and have a smooth surface. The dimensions of individual plates are standardized and can be assembled into circular support layers according to the tower diameter, with edges sealed using curved plates or packing. The product can also be used for trench covers, platform walkways, and internal dividers in equipment that require water-permeable and air-permeable support.

Working Principle

Grating plates play a crucial role in packed towers, bridging the gap between the upper and lower layers. During operation, gas flows from the bottom to the top of the tower through the grating holes into the packing layer, while spray liquid flows downward over the packing and falls back to the bottom sump through the grating holes. The grating strips provide a continuous support surface while ensuring a high hole opening rate, transferring the weight of the packing and liquid hold-up to the tower wall support rings to prevent packing from falling and blocking the lower space.

The shape and spacing of the grating holes are designed to ensure more uniform gas distribution when passing through the support layer, avoiding local high gas velocity that could cause flooding. The smooth plastic grating surface does not react with acidic or alkaline media, remains corrosion-resistant and rust-free even when long-term immersed in spray liquid, and maintains the integrity of the strip cross-section, ensuring that the support capacity does not significantly decrease over time—a clear advantage over metal gratings.

Structural Composition

Grating plates are injection-molded as a single piece, incorporating intersecting strips and a frame to form regular rectangular or bar-shaped through-holes. The frame enhances the overall rigidity of the plate and is used for connecting plates together. Reinforcing ribs can be added to the back of the plate to increase load-bearing capacity without significantly reducing the hole opening rate, allowing individual plates to withstand the load of packing and liquid hold-up.

The entire grating layer is assembled from multiple standard plates. In circular towers, standard rectangular plates are used for the inner layer, while irregular plates are used to fill the edges. Locating structures are provided at the joints to prevent displacement. The grating plates are placed on PP support rings or beams welded to the tower wall. For larger diameter towers, additional support beams may be added in the center to reduce the span of the plates. During installation and maintenance, individual plates can be removed easily for packing replacement.

Specification and Model Table

The table below outlines the structural features and usage instructions of the grating plates. Specific dimensions are matched according to the tower diameter.

Component	Feature	Function
Grating plate surface	Regularly opened holes	Air and liquid passage
Frame reinforcing ribs	Integral molding	Enhance rigidity
Assembly joint	Clip positioning	Layer assembly

Product Features

Compared to manually welded gratings, integral grating plates save labor and material, making them an upgraded choice for packed tower support components. The main features are as follows.

Injection-molded as a single piece, with uniform and high hole opening rates
Flame-retardant PP material, acid/alkali-resistant, and self-extinguishing
Clip assembly without welding, saving labor and shortening project duration
Standardized plates, assembled according to tower diameter, for easy replacement
Smooth surface to prevent fouling, minimizing liquid flow resistance
Lightweight with high strength, maintaining shape under packing load
Comprehensive specifications, also suitable for covers, walkways, and dividers

Material	Flame Retardant PP Polypropylene
Molding Process	Integral injection molding
Flame Retardancy Performance	Self-extinguishing
Corrosion resistance performance	Acid and Alkali Salt Resistant
Panel structure	Grid Opening
Assembly Method	Snap-fit connection
Installation Location	Support rings on the tower
Purpose	Supporting the filler layer
Shape	Round / Sector Segmentation
Load-bearing characteristics	Load-bearing maintenance
Hole Features	High perforation rate, good ventilation

Application Industries

Bottom support for packing layers in spray towers and scrubbing towers
Grating support for packing in acid-alkali exhaust gas absorption towers
Filter support partitions in activated carbon adsorption equipment
Packing support layers in biological deodorization towers and biological filters
Corrosion-resistant sump covers and water tank covers in electroplating workshops
Corrosion-resistant operation platforms and walkway planks in chemical plant areas
Air-liquid distribution plates inside cooling towers and purification equipment

Typical Process Locations

Grating plates are horizontally installed below the packing layer inside the packing tower, resting on the tower's support ring. Below the grating are the inlet section and the tower's bottom gas-liquid space, while above it, loose packing is stacked. For towers with multiple packing layers, grating support layers are installed below each layer, and pressure plates may be added above the packing to prevent it from being blown away by airflow. The grating plate is a mandatory passage for gas-liquid two-phase flow inside the tower.

During the equipment manufacturing process, after the tower body is rolled, welded, and the support ring is welded, the grating plates are introduced into the tower through the manhole before packing installation, assembled piece by piece, fully covering the entire cross-section and securing the edges. For maintenance and packing replacement, the upper packing is removed from the manhole, and the grating plates are extracted piece by piece. When used as sump covers or walkway planks, they are directly laid on supports or the edges of the sump. Before installation, the tower's inner diameter, support ring width, and partition dimensions are verified. The grating plates are introduced piece by piece through the manhole and fully cover the cross-section, with interlocking grooves securely fitted and gaps between edges and tower walls smaller than packing dimensions to prevent loose packing from falling out. Pressure plates are installed above as needed to hold the packing. During operation, the grating is regularly removed for packing maintenance to inspect for broken grating strips, blocked holes, and replace deformed or damaged partitions before reloading the packing.

The size of the grille openings is primarily determined by the filler dimensions. The principle is that the effective gap of the grille openings must be smaller than the minimum outer dimension of the filler to prevent the filler from leaking through the openings. At the same time, while ensuring no leakage, the open area should be maximized to reduce the resistance to gas-liquid passage. When loading small-diameter multi-faced balls or small specifications of Raschig rings, a dense grille with smaller openings should be selected. For larger specifications of fillers, a grille with larger openings and higher air permeability can be chosen. In addition to filler dimensions, the liquid holding capacity and air flow impact must be considered. For grilles with higher open area rates, the reinforcement spacing and support intervals should be checked. During selection, provide the filler specifications, loading height, tower diameter, and gas processing capacity to the manufacturer to match the corresponding grille opening type, plate thickness, and segment combination. For edge irregular areas, curved edge plates should be used to ensure that all gaps in the entire layer are smaller than the filler dimensions.

The load-bearing capacity of grating plate is related to the plate thickness, the structure and orientation of the reinforcement bars, the support span, and the wet weight of the fill material. Injection molded grating plate can bear the weight of conventional bulk fill material and liquid weight within a reasonable spacing of support rings and beams. For large-diameter towers, the load-bearing capacity is ensured by densifying support beams, increasing segments, and reducing the span of individual plates. In design, the total load should be calculated based on the fill material's bulk density, loading height, liquid volume, and potential maintenance loads, and then the plate thickness, reinforcement bars, and support spacing should be determined accordingly. The span of grating plate should not be excessively large without intermediate support, otherwise, long-term loading may cause deflection, deformation, or even detachment. When selecting, prioritize plates with rationally arranged reinforcement bars and solid molding. For conditions with high liquid volume and loading height, the spacing of support beams should be appropriately densified.

It's not the same. They have different positions and functions. Grating plates are installed below the packing layer, primarily to support the entire packing layer, bearing the weight of the packing and the liquid retained. They require high load-bearing capacity and non-leakage openings. Packing support plates, also known as packing limit plates or packing screens, are installed above the packing layer. Their function is to prevent the packing from being blown, fluidized, or carried away by the gas flow at high gas velocities. They experience relatively lower stress, allowing for larger openings. The two work together in an upper-lower combination: the grating below supports the packing to prevent it from falling, while the plate above holds the packing in place to prevent it from floating. They are often installed together in packed towers operating under high gas velocities and large flow rates. When selecting, grating plates are determined based on load-bearing capacity and packing dimensions, while support plates are determined based on gas velocity and anti-carrying requirements. They cannot be mutually substituted. The installation sequence is first to lay the grating, then install the packing, and finally cover the support plate. The reverse sequence is used for maintenance.

圆形塔内整层格栅由标准矩形板块和边缘异形板、弧形边板组合铺满。塔体中部铺设标准板，靠近塔壁的弧形区域用切割成对应弧度的边板补齐，板块之间搭接扣合、相互压边，边缘与塔壁之间的缝隙用散填料、软质密封条或封边条封堵，防止填料从边缘缝隙漏下。格栅板整体搁置在焊接于塔壁的支撑圈和中部支撑梁上，必要时用塑料压块或卡扣固定，防止气流掀动。分块尺寸要考虑能从人孔送入塔内、便于人工搬运和拼装，弧形边板按实际塔径在现场或预制时裁切。铺完后逐块检查是否平稳、有无悬空和大于填料的缝隙，确认合格后再装填填料。

The grating plate surface is smooth, and under normal conditions, impurities carried by the spray liquid are not easily adhered. However, after long-term operation, scale in the water, salt crystallization, or filler debris may accumulate on the plate bars, stiffeners, and splicing joints, gradually reducing the effective open area and increasing resistance. During shutdown maintenance, grating plates can be removed piece by piece, cleaned with high-pressure water, or washed with weak acid compatible with the material to remove crystallization. Severely damaged plate bars or stiffeners should be replaced with new plates. To reduce blockage, start from the front end: enhance pre-treatment and dust removal of exhaust gas, regularly replace circulating liquid, and install filters before the water tank and spray pumps to minimize impurities entering the tower. During operation, assess the degree of grating contamination based on changes in the filler layer resistance, and clean the grating during each shutdown for filler maintenance. After cleaning, the plates should be repositioned and secured in their original positions to avoid large gaps caused by misinstallation.

The plastic grating board is acid and alkali resistant, rustproof, and rot-resistant, making it suitable for outdoor and corrosive environments. However, polypropylene will gradually age and become brittle when exposed to ultraviolet (UV) radiation from sunlight, leading to a decline in mechanical performance. For grating boards, platforms, and walkway panels installed outdoors for long periods, it is recommended to use weather-resistant materials with UV inhibitors or implement shading and covering measures to slow down aging. Grating boards used inside towers and equipment are not exposed to direct sunlight, so aging occurs at a slower rate, and conventional materials are sufficient for long-term use. In cold regions, the low-temperature toughness of the material must also be considered. During winter, the panels become more brittle, so heavy impact and concentrated stacking should be avoided, and handling during installation and maintenance should be gentle. Outdoor platforms can also be treated with anti-slip surfaces and regularly inspected. If panels show obvious brittleness, cracking, or powdering, they should be replaced promptly to eliminate safety hazards.

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