Mud and water transportation link
In the mud and water shield machine, the configured mud and water need to be transported from the mud pool on the ground to the excavation chamber of the shield machine. A large-caliber electric butterfly valve will be used in this process. The electric butterfly valve has the characteristics of simple structure, small size and light weight. It can open and close quickly and effectively control the flow of mud and water. For example, when the shield machine starts to excavate, open the electric butterfly valve to allow mud and water to enter the excavation chamber at a suitable flow rate, providing stable pressure support for the cutterhead to cut the soil.
At the same time, in order to prevent mud from flowing back, check valves will be installed at certain key positions of the mud and water transportation pipeline. The check valve automatically opens and closes using the pressure of the medium itself. When the mud flows forward, the valve opens; once the mud shows a trend of reverse flow, the check valve will immediately close to avoid mud and water backflow and protect the equipment safety of the mud transportation system.
Mud and water separation link
The mud and water discharged from the excavation chamber contains a large amount of slag, which needs to be separated from mud and water. Various regulating valves are installed on the inlet and outlet pipes of the mud-water separation equipment. These regulating valves can accurately control the flow and pressure of mud-water in and out of the separation equipment to ensure the effect of mud-water separation. For example, by adjusting the opening of the valve, mud-water can enter the separation equipment such as the cyclone at a suitable flow rate, so that the slag and mud can be effectively separated.
Application of valves in the grouting system of shield machines
Grouting material storage and transportation
During the excavation process, shield machines need to grout the gaps behind the segments. A manual ball valve is usually installed at the outlet of the grouting material storage tank. The manual ball valve is easy to operate and convenient for controlling the initial outflow of the grouting material. For example, when preparing for grouting, construction workers can manually open the ball valve to allow the grouting material to slowly enter the delivery pipeline.
Along the delivery pipeline of the grouting material, electric regulating valves will be installed. These electric regulating valves can adjust the valve opening in real time according to the requirements of grouting pressure and flow. During the grouting process, the opening of the electric regulating valve is automatically adjusted by monitoring the pressure and flow data fed back by the system, so that the grouting material can be injected into the gap behind the segment at a stable pressure and appropriate flow, ensuring the stability of the segment and the support effect of the formation.
Prevent grouting backflow
In order to prevent the grouting material from backflowing, a one-way valve will be installed at the end of the grouting pipeline near the injection point. The one-way valve ensures that the grouting material can only be injected into the gap behind the segment in one direction, and will not flow back due to factors such as formation pressure. Once the grouting is completed, the one-way valve can prevent the injected grouting material from flowing back and ensure the grouting effect.
Application of valves in the cooling system of shield machines
Cooling water circulation
Many equipment of shield machines, such as motors, hydraulic systems, etc., will generate a lot of heat during operation, which needs to be dissipated through the cooling system. In the cooling water circulation system, a gate valve is generally installed at the outlet of the water pump. The gate valve is characterized by low fluid resistance and almost no resistance when fully opened, which allows the cooling water to circulate smoothly in the system. For example, when the cooling system is started, the gate valve is opened so that the cooling water can flow quickly through the equipment that needs to be cooled.
At the same time, temperature control valves are installed at the various branches of the cooling water pipeline and the entrances of key equipment. The temperature control valve can automatically adjust the valve opening according to the temperature of the equipment. When the equipment temperature rises, the temperature control valve automatically opens to increase the flow of cooling water, thereby effectively reducing the equipment temperature; when the equipment temperature drops to the normal range, the temperature control valve will reduce the opening accordingly to save the use of cooling water.
Pressure control of cooling system
In order to control the pressure of the cooling system, a safety valve is installed in the cooling water circulation system. When the system pressure exceeds the set value of the safety valve, the safety valve will automatically open to discharge part of the cooling water from the system to avoid damage to the cooling system equipment caused by excessive pressure. For example, if the water pump fails and the cooling water pressure rises sharply, the safety valve will play a role to protect the safety of the entire cooling system.
