The spout deck on a recovery boiler is considered the most dangerous area for operators and one of the leading causes of recordable injuries. As such, all operators know that having to plug a single spout for any reason can be a dangerous and time-consuming process. Proper precautions and safety methods are necessary to ensure the safety of operators attempting to plug the spout, as well as preventing harmful materials from dropping into the dissolving tank and affecting overall operations. To improve safety in performing this operation, Valmet has recently developed a refractory plug that is custom shaped for the Valmet insertable smelt spout. This new product is designed to provide a quick and reliable option for operators to intentionally terminate smelt flow to a smelt spout.
How Does it Work?
The Valmet insertable refractory plug was custom designed to quickly and efficiently plug the smelt flow to a smelt spout when necessary. It works by using a high temperature rope wrapped around the plug as a gasket to create a tight seal between the metal spout and the refractory plug. The plug is also high temperature refractory rated for use in recovery boiler lower furnaces, and is designed for both short term and long term use. All of the Valmet custom plugs are kiln fired over a controlled temperature sequence prior to delivery and are available for immediate use, and are significantly easier, quicker and safer to both install and remove than using a rammable material.
The product also includes a stainless steel locking handle integrated into the smelt spout hood enclosure which is designed to quickly install the plug at the proper elevation/alignment and to secure the plug in place to the micro-hood system. The locking handle anchors the plug in the opening with the gasket compressed so it does not unexpectedly become dislodged. It takes approximately 10-20 seconds to install and secure in place which is a significant reduction in time and improvement to operator safety by attempting alternative methods. The locking handle is supported 100% by the micro-hood system to maintain alignment during changes in thermal growth of the boiler.
What are the Benefits of the Reliable Spout Plug?
With the ability to quickly and safely plug a smelt spout, the ability to perform maintenance work or replace damaged shatter jet parts now becomes safer and more straightforward. When the plug is in place it is now easier to inspect and clean hood internals while the unit is online. It also allows for reducing the number of spouts in service to maintain normal smelt flow under lower operating loads. Customers already using Valmet insertable smelt spouts can purchase these plugs and locking handles as a spare part by obtaining a Valmet “starter kit” which includes all parts needed to begin using the plug.
For more information about the Valmet custom Spout plug please contact our Smelt Spout Product Manager Dan Morrison
When it comes to cleaning and emptying chemical recovery boilers, Valmet has the services required to do it swiftly and safely. If the recovery boiler cleaning process starts too quickly, the water being used in the washing process may cause an explosion when it comes into contact with the molten smelt. In the past, this potential threat has been avoided by waiting 15-35 hours to make sure the smelt bed is frozen and safe to clean. To speed up and improve this procedure, Valmet has developed the Smelt-X and Wash-X processes which change the way recovery boiler cleaning is executed.
The Smelt-X process has been specifically designed to alleviate the recovery boiler cleaning process. The bottom section of the recovery boiler furnace is heated during load reduction so that the whole smelt bed becomes molten, and the smelt is extracted from the floor to the dissolving tank using air-operated ejectors. Our custom designed ejectors for each furnace arrangement are made to extend from spouts to lowest point in floor for max extraction. This custom design is unique in the industry, and can’t be matched by our competitors. Our typical extraction time is 1-3 hours and smelt does not touch spouts during the extraction process. The Smelt-X process also allows for chemicals in the smelt bed to be recovered and the amount of strongly alkaline waste water is minimized resulting in savings in both make-up and neutralization chemicals. Due to these features, Smelt-X can be carried out safely in the middle of the operation cycle as well, and the operation can continue with the same spouts without any additional risk of spout failures during the rest of the cycle.
Other benefits include:
- faster cooling – boiler bank and superheater washing can begin sooner
- recovery of chemicals in the smelt bed
- minimisation of wash water volume and alkalinity
- savings in makeup chemicals for black liquor
- savings in neutralization chemicals in waste water plant
- faster floor cleaning for inspection and repairs
- safer floor cleaning – reduced need for mechanical cleaning and/or high pressure washing
- shorter mill shutdown – increase in pulp production
Valmet has also developed a washing service for recovery boilers called Wash-X in which the floor is washed simultaneously with the rest of the boiler using low pressure water sprays and mixing devices installed on the furnace floor. Once the super heaters are clean, the mixing devices are removed and floor is emptied of wash water using smelt ejectors.
The typical Wash-X arrangement for mixing devices and wash water sprays:
- 1 or 2 mixing devices in each spout (operated with pressurized air)
- 8 – 18 primary air port sp rays connected to feedwater or warm water system (depending on floor size)
- black liquor sprays (at least) in front wall (not shown here) spraying warm wash water
The Smelt-X and Wash-X services will save a huge amount of time for companies who need their recovery boiler systems cleaned. Our process will do no damage to your boiler and have you back operating at full strength much faster than any other process on the market. Please contact Mike Ward to arrange an in person meeting to discuss how our Smelt-X and Wash-X services can work for you.
Efficiency, productivity, and operator safety is always at the top of the priority list for any recovery boiler operations superintendent. And superintendents at mills which have experienced serious operator injuries on the spout deck understand that more than anyone. They know the dangers associated with cleaning smelt spouts and they are also aware that time spent cleaning spouts, is time not spent on numerous other recovery boiler tasks. Wondering what other options you may have? Valmet has the solution.
Keeping smelt spouts clean is dirty, dangerous, and time consuming work. Let the Valmet DeckHandTM Smelt Spout Robot take care of that for you instead. The robot is available in a standing or hanging position, depending on your boiler spout deck layout, and is able to move laterally on a sliding rail system to clean all spouts, just like an operator would. The robot has several cleaning options, including; thorough trough cleaning, spot cleaning and opening plugged spouts. These are preprogrammed cleaning patterns set to run at specific intervals. The robot optimizes spout operation with frequent cleaning cycles while allowing the operators to focus on their other tasks. The operators also have the option to initiate additional cleaning of specific problem areas at the push of a button.
Valmet’s DeckHandTM Smelt Spout Robot is a Jack-of-all-trades: Mounted with a camera, the operators can closely inspect operational issues, shatter jet performance and cleaning results from the comfort of the control room. While cleaning, the robot is programmed to, under no circumstances, touch the spout surface which reduces wear from over-rodding and improves spout performance by allowing the frozen smelt layer to remain intact. The robot also has the ability to clean the hood internals and shatter jet using a water lance. Smelt samples can be taken on a scheduled basis or as required by the robot for use in evaluating operational improvements such as reduction efficiency. As an added safety feature, the robot is able to plug a smelt spout in an emergency situation. This keeps operators from entering harm’s way to attempt it manually.
Optical and/or physical safety barriers are installed around the robot for operator protection on the spout deck. If the barrier is broken, the robot will immediately freeze to insure it does not injure any personnel in the vicinity.
Contact Valmet today to see if the DeckHandTM Smelt Spout Robot is right for you.