The first two StaBlox installations: all flue gas tunnels torn out and rebuilt from precast blocks, two plants in two weeks.
Brick tunnels out, precast blocks in, at two plants several hundred miles apart.
Both jobs fell within the same two weeks
In summer 2018, two ammonia plants in the US had all flue gas tunnels in their top-fired reformers removed and rebuilt with the StaBlox system, two installations within two weeks. Once the old tunnels were out and the floor was ready, the crew set one 43 ft tunnel about every 4 hours, and nine tunnels were finished in about 3 days including orifice inserts and the tie-in at both ends, as published in World Fertilizer in April 2019.
Both reformers had conventional brick and mortar tunnels at the furnace floor. Tunnels of that kind are 4 to 10 ft high and 40 to 100 ft long, held up by buttresses, with expansion joints every few feet and side openings made by leaving out half bricks. Their failures come from three sources: weight, material and expansion that the joints cannot follow.
Each plant also wanted a more even flue gas flow. The replacement tunnels carry orifice inserts sized by BD Energy Systems for every opening, so the new walls change the flow pattern along the tubes, not just the masonry.
When a tunnel goes up in an afternoon, it no longer has to be built first and worked around, it can be set at the end of the outage after the scaffolding has come down.
| What | Result |
|---|---|
| Plants | two ammonia plants in the US, all tunnels replaced |
| Timing | summer 2018, both installations within two weeks |
| Speed per tunnel | one 43 ft tunnel about every 4 hours by the end of the job |
| Nine tunnels | about 3 days from start to finish, including inserts and tie-in |
| Learning curve | even while the gapping was being corrected, three walls were assembled and taken apart again within hours |
Once the lids were on, the walls stiffened at once and resisted being rocked, without any mortar. Cold, a tunnel is an assembly of thousands of parts. At temperature it closes into one leak tight body.
The same parts serve a different situation. Picture a top-fired reformer in which a single brick tunnel has collapsed. Blocks, lids and bases in common sizes are kept in stock, so the one tunnel can be rebuilt in a short outage, without masons and without curing, and it can stay in place when the rest of the furnace is rebuilt later. This is a scenario Blasch describes for planning, not a documented plant.
The work was done by a refractory contractor, with Blasch and BD Energy Systems on site. No masons, no mortar, no cure time.
At one plant a badly warped I-beam under the furnace floor was cut out and replaced, then a leveling castable and an insulating firebrick layer went down.
The bases were laid along a string. The first tunnel ended up with gaps that were too wide and the next two came out short, until the crew measured the total length and found the right spacing.
Blocks came in on temporary rollers, one person laid the fiber gaskets, and the rest of the crew kept stacking.
Lids, tie rods and the numbered orifice inserts finished each tunnel to the opening plan.
The five parts of the system, the material and how it handles expansion.
Tube metal temperatures in an ammonia reformer, measured before and after StaBlox.
Ceramic parts for reformers, waste heat boilers and syngas plants.
A refractory contractor with a general crew, overseen by Blasch and BD Energy Systems. No refractory masons were needed.
The spacing of the base blocks. Debris on the swept floor made the calculated gaps too large, and it took the first tunnels to find the right spacing by measuring the full length.
Yes. The installations showed that tunnels can be taken down and rebuilt within hours, so one tunnel can be replaced and tuned in a short outage.
No. The published article describes them as two unnamed US ammonia plants.
Send the number of tunnels, their length and height and the furnace layout. A Blasch engineer works out the parts and the installation plan with your contractor.
